8158 Want named threads API

[unleashed.git] / usr / src / cmd / mdb / common / mdb / mdb_proc.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright 2018 Joyent, Inc.
 * Copyright (c) 2014 by Delphix. All rights reserved.
 */

/*
 * User Process Target
 *
 * The user process target is invoked when the -u or -p command-line options
 * are used, or when an ELF executable file or ELF core file is specified on
 * the command-line.  This target is also selected by default when no target
 * options are present.  In this case, it defaults the executable name to
 * "a.out".  If no process or core file is currently attached, the target
 * functions as a kind of virtual /dev/zero (in accordance with adb(1)
 * semantics); reads from the virtual address space return zeroes and writes
 * fail silently.  The proc target itself is designed as a wrapper around the
 * services provided by libproc.so: t->t_pshandle is set to the struct
 * ps_prochandle pointer returned as a handle by libproc.  The target also
 * opens the executable file itself using the MDB GElf services, for
 * interpreting the .symtab and .dynsym if no libproc handle has been
 * initialized, and for handling i/o to and from the object file.  Currently,
 * the only ISA-dependent portions of the proc target are the $r and ::fpregs
 * dcmds, the callbacks for t_next() and t_step_out(), and the list of named
 * registers; these are linked in from the proc_isadep.c file for each ISA and
 * called from the common code in this file.
 *
 * The user process target implements complete user process control using the
 * facilities provided by libproc.so.  The MDB execution control model and
 * an overview of software event management is described in mdb_target.c.  The
 * proc target implements breakpoints by replacing the instruction of interest
 * with a trap instruction, and then restoring the original instruction to step
 * over the breakpoint.  The idea of replacing program text with instructions
 * that transfer control to the debugger dates back as far as 1951 [1].  When
 * the target stops, we replace each breakpoint with the original instruction
 * as part of the disarm operation.  This means that no special processing is
 * required for t_vread() because the instrumented instructions will never be
 * seen by the debugger once the target stops.  Some debuggers have improved
 * start/stop performance by leaving breakpoint traps in place and then
 * handling a read from a breakpoint address as a special case.  Although this
 * improves efficiency for a source-level debugger, it runs somewhat contrary
 * to the philosophy of the low-level debugger.  Since we remove the
 * instructions, users can apply other external debugging tools to the process
 * once it has stopped (e.g. the proc(1) tools) and not be misled by MDB
 * instrumentation.  The tracing of faults, signals, system calls, and
 * watchpoints and general process inspection is implemented directly using
 * the mechanisms provided by /proc, as described originally in [2] and [3].
 *
 * References
 *
 * [1] S. Gill, "The Diagnosis Of Mistakes In Programmes on the EDSAC",
 *     Proceedings of the Royal Society Series A Mathematical and Physical
 *     Sciences, Cambridge University Press, 206(1087), May 1951, pp. 538-554.
 *
 * [2] T.J. Killian, "Processes as Files", Proceedings of the USENIX Association
 *     Summer Conference, Salt Lake City, June 1984, pp. 203-207.
 *
 * [3] Roger Faulkner and Ron Gomes, "The Process File System and Process
 *     Model in UNIX System V", Proceedings of the USENIX Association
 *     Winter Conference, Dallas, January 1991, pp. 243-252.
 */

#include <mdb/mdb_proc.h>
#include <mdb/mdb_disasm.h>
#include <mdb/mdb_signal.h>
#include <mdb/mdb_string.h>
#include <mdb/mdb_module.h>
#include <mdb/mdb_debug.h>
#include <mdb/mdb_conf.h>
#include <mdb/mdb_err.h>
#include <mdb/mdb_types.h>
#include <mdb/mdb.h>

#include <sys/utsname.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <termio.h>
#include <signal.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>

#define PC_FAKE         -1UL                    /* illegal pc value unequal 0 */
#define PANIC_BUFSIZE   1024

static const char PT_EXEC_PATH[] = "a.out";     /* Default executable */
static const char PT_CORE_PATH[] = "core";      /* Default core file */

static const pt_ptl_ops_t proc_lwp_ops;
static const pt_ptl_ops_t proc_tdb_ops;
static const mdb_se_ops_t proc_brkpt_ops;
static const mdb_se_ops_t proc_wapt_ops;

static int pt_setrun(mdb_tgt_t *, mdb_tgt_status_t *, int);
static void pt_activate_common(mdb_tgt_t *);
static mdb_tgt_vespec_f pt_ignore_sig;
static mdb_tgt_se_f pt_fork;
static mdb_tgt_se_f pt_exec;

static int pt_lookup_by_name_thr(mdb_tgt_t *, const char *,
    const char *, GElf_Sym *, mdb_syminfo_t *, mdb_tgt_tid_t);
static int tlsbase(mdb_tgt_t *, mdb_tgt_tid_t, Lmid_t, const char *,
    psaddr_t *);

/*
 * When debugging postmortem, we don't resolve names as we may very well not
 * be on a system on which those names resolve.
 */
#define PT_LIBPROC_RESOLVE(P) \
        (!(mdb.m_flags & MDB_FL_LMRAW) && Pstate(P) != PS_DEAD)

/*
 * The Perror_printf() function interposes on the default, empty libproc
 * definition.  It will be called to report additional information on complex
 * errors, such as a corrupt core file.  We just pass the args to vwarn.
 */
/*ARGSUSED*/
void
Perror_printf(struct ps_prochandle *P, const char *format, ...)
{
        va_list alist;

        va_start(alist, format);
        vwarn(format, alist);
        va_end(alist);
}

/*
 * Open the specified i/o backend as the a.out executable file, and attempt to
 * load its standard and dynamic symbol tables.  Note that if mdb_gelf_create
 * succeeds, io is assigned to p_fio and is automatically held by gelf_create.
 */
static mdb_gelf_file_t *
pt_open_aout(mdb_tgt_t *t, mdb_io_t *io)
{
        pt_data_t *pt = t->t_data;
        GElf_Sym s1, s2;

        if ((pt->p_file = mdb_gelf_create(io, ET_NONE, GF_FILE)) == NULL)
                return (NULL);

        pt->p_symtab = mdb_gelf_symtab_create_file(pt->p_file,
            SHT_SYMTAB, MDB_TGT_SYMTAB);
        pt->p_dynsym = mdb_gelf_symtab_create_file(pt->p_file,
            SHT_DYNSYM, MDB_TGT_DYNSYM);

        /*
         * If we've got an _start symbol with a zero size, prime the private
         * symbol table with a copy of _start with its size set to the distance
         * between _mcount and _start.  We do this because DevPro has shipped
         * the Intel crt1.o without proper .size directives for years, which
         * precludes proper identification of _start in stack traces.
         */
        if (mdb_gelf_symtab_lookup_by_name(pt->p_dynsym, "_start", &s1,
            NULL) == 0 && s1.st_size == 0 &&
            GELF_ST_TYPE(s1.st_info) == STT_FUNC) {
                if (mdb_gelf_symtab_lookup_by_name(pt->p_dynsym, "_mcount",
                    &s2, NULL) == 0 && GELF_ST_TYPE(s2.st_info) == STT_FUNC) {
                        s1.st_size = s2.st_value - s1.st_value;
                        mdb_gelf_symtab_insert(mdb.m_prsym, "_start", &s1);
                }
        }

        pt->p_fio = io;
        return (pt->p_file);
}

/*
 * Destroy the symbol tables and GElf file object associated with p_fio.  Note
 * that we do not need to explicitly free p_fio: its reference count is
 * automatically decremented by mdb_gelf_destroy, which will free it if needed.
 */
static void
pt_close_aout(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;

        if (pt->p_symtab != NULL) {
                mdb_gelf_symtab_destroy(pt->p_symtab);
                pt->p_symtab = NULL;
        }

        if (pt->p_dynsym != NULL) {
                mdb_gelf_symtab_destroy(pt->p_dynsym);
                pt->p_dynsym = NULL;
        }

        if (pt->p_file != NULL) {
                mdb_gelf_destroy(pt->p_file);
                pt->p_file = NULL;
        }

        mdb_gelf_symtab_delete(mdb.m_prsym, "_start", NULL);
        pt->p_fio = NULL;
}

typedef struct tdb_mapping {
        const char *tm_thr_lib;
        const char *tm_db_dir;
        const char *tm_db_name;
} tdb_mapping_t;

static const tdb_mapping_t tdb_map[] = {
        { "/lwp/amd64/libthread.so",    "/usr/lib/lwp/", "libthread_db.so" },
        { "/lwp/sparcv9/libthread.so",  "/usr/lib/lwp/", "libthread_db.so" },
        { "/lwp/libthread.so",          "/usr/lib/lwp/", "libthread_db.so" },
        { "/libthread.so",              "/lib/", "libthread_db.so" },
        { "/libc_hwcap",                "/lib/", "libc_db.so" },
        { "/libc.so",                   "/lib/", "libc_db.so" }
};

/*
 * Pobject_iter callback that we use to search for the presence of libthread in
 * order to load the corresponding libthread_db support.  We derive the
 * libthread_db path dynamically based on the libthread path.  If libthread is
 * found, this function returns 1 (and thus Pobject_iter aborts and returns 1)
 * regardless of whether it was successful in loading the libthread_db support.
 * If we iterate over all objects and no libthread is found, 0 is returned.
 * Since libthread_db support was then merged into libc_db, we load either
 * libc_db or libthread_db, depending on which library we see first.
 */
/*ARGSUSED*/
static int
thr_check(mdb_tgt_t *t, const prmap_t *pmp, const char *name)
{
        pt_data_t *pt = t->t_data;
        const mdb_tdb_ops_t *ops;
        char *p;

        char path[MAXPATHLEN];

        int libn;

        if (name == NULL)
                return (0); /* no rtld_db object name; keep going */

        for (libn = 0; libn < sizeof (tdb_map) / sizeof (tdb_map[0]); libn++) {
                if ((p = strstr(name, tdb_map[libn].tm_thr_lib)) != NULL)
                        break;
        }

        if (p == NULL)
                return (0); /* no match; keep going */

        path[0] = '\0';
        (void) strlcat(path, mdb.m_root, sizeof (path));
        (void) strlcat(path, tdb_map[libn].tm_db_dir, sizeof (path));
#if !defined(_ILP32)
        (void) strlcat(path, "64/", sizeof (path));
#endif /* !_ILP32 */
        (void) strlcat(path, tdb_map[libn].tm_db_name, sizeof (path));

        /* Append the trailing library version number. */
        (void) strlcat(path, strrchr(name, '.'), sizeof (path));

        if ((ops = mdb_tdb_load(path)) == NULL) {
                if (libn != 0 || errno != ENOENT)
                        warn("failed to load %s", path);
                goto err;
        }

        if (ops == pt->p_tdb_ops)
                return (1); /* no changes needed */

        PTL_DTOR(t);
        pt->p_tdb_ops = ops;
        pt->p_ptl_ops = &proc_tdb_ops;
        pt->p_ptl_hdl = NULL;

        if (PTL_CTOR(t) == -1) {
                warn("failed to initialize %s", path);
                goto err;
        }

        mdb_dprintf(MDB_DBG_TGT, "loaded %s for debugging %s\n", path, name);
        (void) mdb_tgt_status(t, &t->t_status);
        return (1);
err:
        PTL_DTOR(t);
        pt->p_tdb_ops = NULL;
        pt->p_ptl_ops = &proc_lwp_ops;
        pt->p_ptl_hdl = NULL;

        if (libn != 0 || errno != ENOENT) {
                warn("warning: debugger will only be able to "
                    "examine raw LWPs\n");
        }

        (void) mdb_tgt_status(t, &t->t_status);
        return (1);
}

/*
 * Whenever the link map is consistent following an add or delete event, we ask
 * libproc to update its mappings, check to see if we need to load libthread_db,
 * and then update breakpoints which have been mapped or unmapped.
 */
/*ARGSUSED*/
static void
pt_rtld_event(mdb_tgt_t *t, int vid, void *private)
{
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;
        rd_event_msg_t rdm;
        int docontinue = 1;

        if (rd_event_getmsg(pt->p_rtld, &rdm) == RD_OK) {

                mdb_dprintf(MDB_DBG_TGT, "rtld event type 0x%x state 0x%x\n",
                    rdm.type, rdm.u.state);

                if (rdm.type == RD_DLACTIVITY && rdm.u.state == RD_CONSISTENT) {
                        mdb_sespec_t *sep, *nsep = mdb_list_next(&t->t_active);
                        pt_brkpt_t *ptb;

                        Pupdate_maps(P);

                        if (Pobject_iter(P, (proc_map_f *)thr_check, t) == 0 &&
                            pt->p_ptl_ops != &proc_lwp_ops) {
                                mdb_dprintf(MDB_DBG_TGT, "unloading thread_db "
                                    "support after dlclose\n");
                                PTL_DTOR(t);
                                pt->p_tdb_ops = NULL;
                                pt->p_ptl_ops = &proc_lwp_ops;
                                pt->p_ptl_hdl = NULL;
                                (void) mdb_tgt_status(t, &t->t_status);
                        }

                        for (sep = nsep; sep != NULL; sep = nsep) {
                                nsep = mdb_list_next(sep);
                                ptb = sep->se_data;

                                if (sep->se_ops == &proc_brkpt_ops &&
                                    Paddr_to_map(P, ptb->ptb_addr) == NULL)
                                        mdb_tgt_sespec_idle_one(t, sep,
                                            EMDB_NOMAP);
                        }

                        if (!mdb_tgt_sespec_activate_all(t) &&
                            (mdb.m_flags & MDB_FL_BPTNOSYMSTOP) &&
                            pt->p_rtld_finished) {
                                /*
                                 * We weren't able to activate the breakpoints.
                                 * If so requested, we'll return without
                                 * calling continue, thus throwing the user into
                                 * the debugger.
                                 */
                                docontinue = 0;
                        }

                        if (pt->p_rdstate == PT_RD_ADD)
                                pt->p_rdstate = PT_RD_CONSIST;
                }

                if (rdm.type == RD_PREINIT)
                        (void) mdb_tgt_sespec_activate_all(t);

                if (rdm.type == RD_POSTINIT) {
                        pt->p_rtld_finished = TRUE;
                        if (!mdb_tgt_sespec_activate_all(t) &&
                            (mdb.m_flags & MDB_FL_BPTNOSYMSTOP)) {
                                /*
                                 * Now that rtld has been initialized, we
                                 * should be able to initialize all deferred
                                 * breakpoints.  If we can't, don't let the
                                 * target continue.
                                 */
                                docontinue = 0;
                        }
                }

                if (rdm.type == RD_DLACTIVITY && rdm.u.state == RD_ADD &&
                    pt->p_rtld_finished)
                        pt->p_rdstate = MAX(pt->p_rdstate, PT_RD_ADD);
        }

        if (docontinue)
                (void) mdb_tgt_continue(t, NULL);
}

static void
pt_post_attach(mdb_tgt_t *t)
{
        struct ps_prochandle *P = t->t_pshandle;
        const lwpstatus_t *psp = &Pstatus(P)->pr_lwp;
        pt_data_t *pt = t->t_data;
        int hflag = MDB_TGT_SPEC_HIDDEN;

        mdb_dprintf(MDB_DBG_TGT, "attach pr_flags=0x%x pr_why=%d pr_what=%d\n",
            psp->pr_flags, psp->pr_why, psp->pr_what);

        /*
         * When we grab a process, the initial setting of p_rtld_finished
         * should be false if the process was just created by exec; otherwise
         * we permit unscoped references to resolve because we do not know how
         * far the process has proceeded through linker initialization.
         */
        if ((psp->pr_flags & PR_ISTOP) && psp->pr_why == PR_SYSEXIT &&
            psp->pr_errno == 0 && psp->pr_what == SYS_execve) {
                if (mdb.m_target == NULL) {
                        warn("target performed exec of %s\n",
                            IOP_NAME(pt->p_fio));
                }
                pt->p_rtld_finished = FALSE;
        } else
                pt->p_rtld_finished = TRUE;

        /*
         * When we grab a process, if it is stopped by job control and part of
         * the same session (i.e. same controlling tty), set MDB_FL_JOBCTL so
         * we will know to bring it to the foreground when we continue it.
         */
        if (mdb.m_term != NULL && (psp->pr_flags & PR_STOPPED) &&
            psp->pr_why == PR_JOBCONTROL && getsid(0) == Pstatus(P)->pr_sid)
                mdb.m_flags |= MDB_FL_JOBCTL;

        /*
         * When we grab control of a live process, set F_RDWR so that the
         * target layer permits writes to the target's address space.
         */
        t->t_flags |= MDB_TGT_F_RDWR;

        (void) Pfault(P, FLTBPT, TRUE);         /* always trace breakpoints */
        (void) Pfault(P, FLTWATCH, TRUE);       /* always trace watchpoints */
        (void) Pfault(P, FLTTRACE, TRUE);       /* always trace single-step */

        (void) Punsetflags(P, PR_ASYNC);        /* require synchronous mode */
        (void) Psetflags(P, PR_BPTADJ);         /* always adjust eip on x86 */
        (void) Psetflags(P, PR_FORK);           /* inherit tracing on fork */

        /*
         * Install event specifiers to track fork and exec activities:
         */
        (void) mdb_tgt_add_sysexit(t, SYS_vfork, hflag, pt_fork, NULL);
        (void) mdb_tgt_add_sysexit(t, SYS_forksys, hflag, pt_fork, NULL);
        (void) mdb_tgt_add_sysexit(t, SYS_execve, hflag, pt_exec, NULL);

        /*
         * Attempt to instantiate the librtld_db agent and set breakpoints
         * to track rtld activity.  We will legitimately fail to instantiate
         * the rtld_db agent if the target is statically linked.
         */
        if (pt->p_rtld == NULL && (pt->p_rtld = Prd_agent(P)) != NULL) {
                rd_notify_t rdn;
                rd_err_e err;

                if ((err = rd_event_enable(pt->p_rtld, TRUE)) != RD_OK) {
                        warn("failed to enable rtld_db event tracing: %s\n",
                            rd_errstr(err));
                        goto out;
                }

                if ((err = rd_event_addr(pt->p_rtld, RD_PREINIT,
                    &rdn)) == RD_OK && rdn.type == RD_NOTIFY_BPT) {
                        (void) mdb_tgt_add_vbrkpt(t, rdn.u.bptaddr,
                            hflag, pt_rtld_event, NULL);
                } else {
                        warn("failed to install rtld_db preinit tracing: %s\n",
                            rd_errstr(err));
                }

                if ((err = rd_event_addr(pt->p_rtld, RD_POSTINIT,
                    &rdn)) == RD_OK && rdn.type == RD_NOTIFY_BPT) {
                        (void) mdb_tgt_add_vbrkpt(t, rdn.u.bptaddr,
                            hflag, pt_rtld_event, NULL);
                } else {
                        warn("failed to install rtld_db postinit tracing: %s\n",
                            rd_errstr(err));
                }

                if ((err = rd_event_addr(pt->p_rtld, RD_DLACTIVITY,
                    &rdn)) == RD_OK && rdn.type == RD_NOTIFY_BPT) {
                        (void) mdb_tgt_add_vbrkpt(t, rdn.u.bptaddr,
                            hflag, pt_rtld_event, NULL);
                } else {
                        warn("failed to install rtld_db activity tracing: %s\n",
                            rd_errstr(err));
                }
        }
out:
        Pupdate_maps(P);
        Psync(P);

        /*
         * If librtld_db failed to initialize due to an error or because we are
         * debugging a statically linked executable, allow unscoped references.
         */
        if (pt->p_rtld == NULL)
                pt->p_rtld_finished = TRUE;

        (void) mdb_tgt_sespec_activate_all(t);
}

/*ARGSUSED*/
static int
pt_vespec_delete(mdb_tgt_t *t, void *private, int id, void *data)
{
        if (id < 0) {
                ASSERT(data == NULL); /* we don't use any ve_data */
                (void) mdb_tgt_vespec_delete(t, id);
        }
        return (0);
}

static void
pt_pre_detach(mdb_tgt_t *t, int clear_matched)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        pt_data_t *pt = t->t_data;
        long cmd = 0;

        /*
         * If we are about to release the process and it is stopped on a traced
         * SIGINT, breakpoint fault, single-step fault, or watchpoint, make
         * sure to clear this event prior to releasing the process so that it
         * does not subsequently reissue the fault and die from SIGTRAP.
         */
        if (psp->pr_flags & PR_ISTOP) {
                if (psp->pr_why == PR_FAULTED && (psp->pr_what == FLTBPT ||
                    psp->pr_what == FLTTRACE || psp->pr_what == FLTWATCH))
                        cmd = PCCFAULT;
                else if (psp->pr_why == PR_SIGNALLED && psp->pr_what == SIGINT)
                        cmd = PCCSIG;

                if (cmd != 0)
                        (void) write(Pctlfd(t->t_pshandle), &cmd, sizeof (cmd));
        }

        if (Pstate(t->t_pshandle) == PS_UNDEAD)
                (void) waitpid(Pstatus(t->t_pshandle)->pr_pid, NULL, WNOHANG);

        (void) mdb_tgt_vespec_iter(t, pt_vespec_delete, NULL);
        mdb_tgt_sespec_idle_all(t, EMDB_NOPROC, clear_matched);

        if (pt->p_fio != pt->p_aout_fio) {
                pt_close_aout(t);
                (void) pt_open_aout(t, pt->p_aout_fio);
        }

        PTL_DTOR(t);
        pt->p_tdb_ops = NULL;
        pt->p_ptl_ops = &proc_lwp_ops;
        pt->p_ptl_hdl = NULL;

        pt->p_rtld = NULL;
        pt->p_signal = 0;
        pt->p_rtld_finished = FALSE;
        pt->p_rdstate = PT_RD_NONE;
}

static void
pt_release_parents(mdb_tgt_t *t)
{
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;

        mdb_sespec_t *sep;
        pt_vforkp_t *vfp;

        while ((vfp = mdb_list_next(&pt->p_vforkp)) != NULL) {
                mdb_dprintf(MDB_DBG_TGT, "releasing vfork parent %d\n",
                    (int)Pstatus(vfp->p_pshandle)->pr_pid);

                /*
                 * To release vfork parents, we must also wipe out any armed
                 * events in the parent by switching t_pshandle and calling
                 * se_disarm().  Do not change states or lose the matched list.
                 */
                t->t_pshandle = vfp->p_pshandle;

                for (sep = mdb_list_next(&t->t_active); sep != NULL;
                    sep = mdb_list_next(sep)) {
                        if (sep->se_state == MDB_TGT_SPEC_ARMED)
                                (void) sep->se_ops->se_disarm(t, sep);
                }

                t->t_pshandle = P;

                Prelease(vfp->p_pshandle, PRELEASE_CLEAR);
                mdb_list_delete(&pt->p_vforkp, vfp);
                mdb_free(vfp, sizeof (pt_vforkp_t));
        }
}

/*ARGSUSED*/
static void
pt_fork(mdb_tgt_t *t, int vid, void *private)
{
        struct ps_prochandle *P = t->t_pshandle;
        const lwpstatus_t *psp = &Pstatus(P)->pr_lwp;
        pt_data_t *pt = t->t_data;
        mdb_sespec_t *sep;

        int follow_parent = mdb.m_forkmode != MDB_FM_CHILD;
        int is_vfork = (psp->pr_what == SYS_vfork ||
            (psp->pr_what == SYS_forksys && psp->pr_sysarg[0] == 2));

        struct ps_prochandle *C;
        const lwpstatus_t *csp;
        char sysname[32];
        int gcode;
        char c;

        mdb_dprintf(MDB_DBG_TGT, "parent %s: errno=%d rv1=%ld rv2=%ld\n",
            proc_sysname(psp->pr_what, sysname, sizeof (sysname)),
            psp->pr_errno, psp->pr_rval1, psp->pr_rval2);

        if (psp->pr_errno != 0) {
                (void) mdb_tgt_continue(t, NULL);
                return; /* fork failed */
        }

        /*
         * If forkmode is ASK and stdout is a terminal, then ask the user to
         * explicitly set the fork behavior for this particular fork.
         */
        if (mdb.m_forkmode == MDB_FM_ASK && mdb.m_term != NULL) {
                mdb_iob_printf(mdb.m_err, "%s: %s detected: follow (p)arent "
                    "or (c)hild? ", mdb.m_pname, sysname);
                mdb_iob_flush(mdb.m_err);

                while (IOP_READ(mdb.m_term, &c, sizeof (c)) == sizeof (c)) {
                        if (c == 'P' || c == 'p') {
                                mdb_iob_printf(mdb.m_err, "%c\n", c);
                                follow_parent = TRUE;
                                break;
                        } else if (c == 'C' || c == 'c') {
                                mdb_iob_printf(mdb.m_err, "%c\n", c);
                                follow_parent = FALSE;
                                break;
                        }
                }
        }

        /*
         * The parent is now stopped on exit from its fork call.  We must now
         * grab the child on its return from fork in order to manipulate it.
         */
        if ((C = Pgrab(psp->pr_rval1, PGRAB_RETAIN, &gcode)) == NULL) {
                warn("failed to grab forked child process %ld: %s\n",
                    psp->pr_rval1, Pgrab_error(gcode));
                return; /* just stop if we failed to grab the child */
        }

        /*
         * We may have grabbed the child and stopped it prematurely before it
         * stopped on exit from fork.  If so, wait up to 1 sec for it to settle.
         */
        if (Pstatus(C)->pr_lwp.pr_why != PR_SYSEXIT)
                (void) Pwait(C, MILLISEC);

        csp = &Pstatus(C)->pr_lwp;

        if (csp->pr_why != PR_SYSEXIT ||
            (csp->pr_what != SYS_vfork && csp->pr_what != SYS_forksys)) {
                warn("forked child process %ld did not stop on exit from "
                    "fork as expected\n", psp->pr_rval1);
        }

        warn("target forked child process %ld (debugger following %s)\n",
            psp->pr_rval1, follow_parent ? "parent" : "child");

        (void) Punsetflags(C, PR_ASYNC);        /* require synchronous mode */
        (void) Psetflags(C, PR_BPTADJ);         /* always adjust eip on x86 */
        (void) Prd_agent(C);                    /* initialize librtld_db */

        /*
         * At the time pt_fork() is called, the target event engine has already
         * disarmed the specifiers on the active list, clearing out events in
         * the parent process.  However, this means that events that change
         * the address space (e.g. breakpoints) have not been effectively
         * disarmed in the child since its address space reflects the state of
         * the process at the time of fork when events were armed.  We must
         * therefore handle this as a special case and re-invoke the disarm
         * callback of each active specifier to clean out the child process.
         */
        if (!is_vfork) {
                for (t->t_pshandle = C, sep = mdb_list_next(&t->t_active);
                    sep != NULL; sep = mdb_list_next(sep)) {
                        if (sep->se_state == MDB_TGT_SPEC_ACTIVE)
                                (void) sep->se_ops->se_disarm(t, sep);
                }

                t->t_pshandle = P; /* restore pshandle to parent */
        }

        /*
         * If we're following the parent process, we need to temporarily change
         * t_pshandle to refer to the child handle C so that we can clear out
         * all the events in the child prior to releasing it below.  If we are
         * tracing a vfork, we also need to explicitly wait for the child to
         * exec, exit, or die before we can reset and continue the parent.  We
         * avoid having to deal with the vfork child forking again by clearing
         * PR_FORK and setting PR_RLC; if it does fork it will effectively be
         * released from our control and we will continue following the parent.
         */
        if (follow_parent) {
                if (is_vfork) {
                        mdb_tgt_status_t status;

                        ASSERT(psp->pr_flags & PR_VFORKP);
                        mdb_tgt_sespec_idle_all(t, EBUSY, FALSE);
                        t->t_pshandle = C;

                        (void) Psysexit(C, SYS_execve, TRUE);

                        (void) Punsetflags(C, PR_FORK | PR_KLC);
                        (void) Psetflags(C, PR_RLC);

                        do {
                                if (pt_setrun(t, &status, 0) == -1 ||
                                    status.st_state == MDB_TGT_UNDEAD ||
                                    status.st_state == MDB_TGT_LOST)
                                        break; /* failure or process died */

                        } while (csp->pr_why != PR_SYSEXIT ||
                            csp->pr_errno != 0 || csp->pr_what != SYS_execve);
                } else
                        t->t_pshandle = C;
        }

        /*
         * If we are following the child, destroy any active libthread_db
         * handle before we release the parent process.
         */
        if (!follow_parent) {
                PTL_DTOR(t);
                pt->p_tdb_ops = NULL;
                pt->p_ptl_ops = &proc_lwp_ops;
                pt->p_ptl_hdl = NULL;
        }

        /*
         * Idle all events to make sure the address space and tracing flags are
         * restored, and then release the process we are not tracing.  If we
         * are following the child of a vfork, we push the parent's pshandle
         * on to a list of vfork parents to be released when we exec or exit.
         */
        if (is_vfork && !follow_parent) {
                pt_vforkp_t *vfp = mdb_alloc(sizeof (pt_vforkp_t), UM_SLEEP);

                ASSERT(psp->pr_flags & PR_VFORKP);
                vfp->p_pshandle = P;
                mdb_list_append(&pt->p_vforkp, vfp);
                mdb_tgt_sespec_idle_all(t, EBUSY, FALSE);

        } else {
                mdb_tgt_sespec_idle_all(t, EBUSY, FALSE);
                Prelease(t->t_pshandle, PRELEASE_CLEAR);
                if (!follow_parent)
                        pt_release_parents(t);
        }

        /*
         * Now that all the hard stuff is done, switch t_pshandle back to the
         * process we are following and reset our events to the ACTIVE state.
         * If we are following the child, reset the libthread_db handle as well
         * as the rtld agent.
         */
        if (follow_parent)
                t->t_pshandle = P;
        else {
                t->t_pshandle = C;
                pt->p_rtld = Prd_agent(C);
                (void) Pobject_iter(t->t_pshandle, (proc_map_f *)thr_check, t);
        }

        (void) mdb_tgt_sespec_activate_all(t);
        (void) mdb_tgt_continue(t, NULL);
}

/*ARGSUSED*/
static void
pt_exec(mdb_tgt_t *t, int vid, void *private)
{
        struct ps_prochandle *P = t->t_pshandle;
        const pstatus_t *psp = Pstatus(P);
        pt_data_t *pt = t->t_data;
        int follow_exec = mdb.m_execmode == MDB_EM_FOLLOW;
        pid_t pid = psp->pr_pid;

        char execname[MAXPATHLEN];
        mdb_sespec_t *sep, *nsep;
        mdb_io_t *io;
        char c;

        mdb_dprintf(MDB_DBG_TGT, "exit from %s: errno=%d\n", proc_sysname(
            psp->pr_lwp.pr_what, execname, sizeof (execname)),
            psp->pr_lwp.pr_errno);

        if (psp->pr_lwp.pr_errno != 0) {
                (void) mdb_tgt_continue(t, NULL);
                return; /* exec failed */
        }

        /*
         * If execmode is ASK and stdout is a terminal, then ask the user to
         * explicitly set the exec behavior for this particular exec.  If
         * Pstate() still shows PS_LOST, we are being called from pt_setrun()
         * directly and therefore we must resume the terminal since it is still
         * in the suspended state as far as tgt_continue() is concerned.
         */
        if (mdb.m_execmode == MDB_EM_ASK && mdb.m_term != NULL) {
                if (Pstate(P) == PS_LOST)
                        IOP_RESUME(mdb.m_term);

                mdb_iob_printf(mdb.m_err, "%s: %s detected: (f)ollow new "
                    "program or (s)top? ", mdb.m_pname, execname);
                mdb_iob_flush(mdb.m_err);

                while (IOP_READ(mdb.m_term, &c, sizeof (c)) == sizeof (c)) {
                        if (c == 'F' || c == 'f') {
                                mdb_iob_printf(mdb.m_err, "%c\n", c);
                                follow_exec = TRUE;
                                break;
                        } else if (c == 'S' || c == 's') {
                                mdb_iob_printf(mdb.m_err, "%c\n", c);
                                follow_exec = FALSE;
                                break;
                        }
                }

                if (Pstate(P) == PS_LOST)
                        IOP_SUSPEND(mdb.m_term);
        }

        pt_release_parents(t);  /* release any waiting vfork parents */
        pt_pre_detach(t, FALSE); /* remove our breakpoints and idle events */
        Preset_maps(P);         /* libproc must delete mappings and symtabs */
        pt_close_aout(t);       /* free pt symbol tables and GElf file data */

        /*
         * If we lost control of the process across the exec and are not able
         * to reopen it, we have no choice but to clear the matched event list
         * and wait for the user to quit or otherwise release the process.
         */
        if (Pstate(P) == PS_LOST && Preopen(P) == -1) {
                int error = errno;

                warn("lost control of PID %d due to exec of %s executable\n",
                    (int)pid, error == EOVERFLOW ? "64-bit" : "set-id");

                for (sep = t->t_matched; sep != T_SE_END; sep = nsep) {
                        nsep = sep->se_matched;
                        sep->se_matched = NULL;
                        mdb_tgt_sespec_rele(t, sep);
                }

                if (error != EOVERFLOW)
                        return; /* just stop if we exec'd a set-id executable */
        }

        if (Pstate(P) != PS_LOST) {
                if (Pexecname(P, execname, sizeof (execname)) == NULL) {
                        (void) mdb_iob_snprintf(execname, sizeof (execname),
                            "/proc/%d/object/a.out", (int)pid);
                }

                if (follow_exec == FALSE || psp->pr_dmodel == PR_MODEL_NATIVE)
                        warn("target performed exec of %s\n", execname);

                io = mdb_fdio_create_path(NULL, execname, pt->p_oflags, 0);
                if (io == NULL) {
                        warn("failed to open %s", execname);
                        warn("a.out symbol tables will not be available\n");
                } else if (pt_open_aout(t, io) == NULL) {
                        (void) mdb_dis_select(pt_disasm(NULL));
                        mdb_io_destroy(io);
                } else
                        (void) mdb_dis_select(pt_disasm(&pt->p_file->gf_ehdr));
        }

        /*
         * We reset our libthread_db state here, but deliberately do NOT call
         * PTL_DTOR because we do not want to call libthread_db's td_ta_delete.
         * This interface is hopelessly broken in that it writes to the process
         * address space (which we do not want it to do after an exec) and it
         * doesn't bother deallocating any of its storage anyway.
         */
        pt->p_tdb_ops = NULL;
        pt->p_ptl_ops = &proc_lwp_ops;
        pt->p_ptl_hdl = NULL;

        if (follow_exec && psp->pr_dmodel != PR_MODEL_NATIVE) {
                const char *argv[3];
                char *state, *env;
                char pidarg[16];
                size_t envlen;

                if (realpath(getexecname(), execname) == NULL) {
                        warn("cannot follow PID %d -- failed to resolve "
                            "debugger pathname for re-exec", (int)pid);
                        return;
                }

                warn("restarting debugger to follow PID %d ...\n", (int)pid);
                mdb_dprintf(MDB_DBG_TGT, "re-exec'ing %s\n", execname);

                (void) mdb_snprintf(pidarg, sizeof (pidarg), "-p%d", (int)pid);

                state = mdb_get_config();
                envlen = strlen(MDB_CONFIG_ENV_VAR) + 1 + strlen(state) + 1;
                env = mdb_alloc(envlen, UM_SLEEP);
                (void) snprintf(env, envlen,
                    "%s=%s", MDB_CONFIG_ENV_VAR, state);

                (void) putenv(env);

                argv[0] = mdb.m_pname;
                argv[1] = pidarg;
                argv[2] = NULL;

                if (mdb.m_term != NULL)
                        IOP_SUSPEND(mdb.m_term);

                Prelease(P, PRELEASE_CLEAR | PRELEASE_HANG);
                (void) execv(execname, (char *const *)argv);
                warn("failed to re-exec debugger");

                if (mdb.m_term != NULL)
                        IOP_RESUME(mdb.m_term);

                t->t_pshandle = pt->p_idlehandle;
                return;
        }

        pt_post_attach(t);      /* install tracing flags and activate events */
        pt_activate_common(t);  /* initialize librtld_db and libthread_db */

        if (psp->pr_dmodel != PR_MODEL_NATIVE && mdb.m_term != NULL) {
                warn("loadable dcmds will not operate on non-native %d-bit "
                    "data model\n", psp->pr_dmodel == PR_MODEL_ILP32 ? 32 : 64);
                warn("use ::release -a and then run mdb -p %d to restart "
                    "debugger\n", (int)pid);
        }

        if (follow_exec)
                (void) mdb_tgt_continue(t, NULL);
}

static int
pt_setflags(mdb_tgt_t *t, int flags)
{
        pt_data_t *pt = t->t_data;

        if ((flags ^ t->t_flags) & MDB_TGT_F_RDWR) {
                int mode = (flags & MDB_TGT_F_RDWR) ? O_RDWR : O_RDONLY;
                mdb_io_t *io;

                if (pt->p_fio == NULL)
                        return (set_errno(EMDB_NOEXEC));

                io = mdb_fdio_create_path(NULL, IOP_NAME(pt->p_fio), mode, 0);

                if (io == NULL)
                        return (-1); /* errno is set for us */

                t->t_flags = (t->t_flags & ~MDB_TGT_F_RDWR) |
                    (flags & MDB_TGT_F_RDWR);

                pt->p_fio = mdb_io_hold(io);
                mdb_io_rele(pt->p_file->gf_io);
                pt->p_file->gf_io = pt->p_fio;
        }

        if (flags & MDB_TGT_F_FORCE) {
                t->t_flags |= MDB_TGT_F_FORCE;
                pt->p_gflags |= PGRAB_FORCE;
        }

        return (0);
}

/*ARGSUSED*/
static int
pt_frame(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
    const mdb_tgt_gregset_t *gregs)
{
        argc = MIN(argc, (uint_t)(uintptr_t)arglim);
        mdb_printf("%a(", pc);

        if (argc != 0) {
                mdb_printf("%lr", *argv++);
                for (argc--; argc != 0; argc--)
                        mdb_printf(", %lr", *argv++);
        }

        mdb_printf(")\n");
        return (0);
}

static int
pt_framev(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
    const mdb_tgt_gregset_t *gregs)
{
        argc = MIN(argc, (uint_t)(uintptr_t)arglim);
#if defined(__i386) || defined(__amd64)
        mdb_printf("%0?lr %a(", gregs->gregs[R_FP], pc);
#else
        mdb_printf("%0?lr %a(", gregs->gregs[R_SP], pc);
#endif
        if (argc != 0) {
                mdb_printf("%lr", *argv++);
                for (argc--; argc != 0; argc--)
                        mdb_printf(", %lr", *argv++);
        }

        mdb_printf(")\n");
        return (0);
}

static int
pt_framer(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
    const mdb_tgt_gregset_t *gregs)
{
        if (pt_frameregs(arglim, pc, argc, argv, gregs, pc == PC_FAKE) == -1) {
                /*
                 * Use verbose format if register format is not supported.
                 */
                return (pt_framev(arglim, pc, argc, argv, gregs));
        }

        return (0);
}

/*ARGSUSED*/
static int
pt_stack_common(uintptr_t addr, uint_t flags, int argc,
    const mdb_arg_t *argv, mdb_tgt_stack_f *func, prgreg_t saved_pc)
{
        void *arg = (void *)(uintptr_t)mdb.m_nargs;
        mdb_tgt_t *t = mdb.m_target;
        mdb_tgt_gregset_t gregs;

        if (argc != 0) {
                if (argv->a_type == MDB_TYPE_CHAR || argc > 1)
                        return (DCMD_USAGE);

                if (argv->a_type == MDB_TYPE_STRING)
                        arg = (void *)(uintptr_t)mdb_strtoull(argv->a_un.a_str);
                else
                        arg = (void *)(uintptr_t)argv->a_un.a_val;
        }

        if (t->t_pshandle == NULL || Pstate(t->t_pshandle) == PS_IDLE) {
                mdb_warn("no process active\n");
                return (DCMD_ERR);
        }

        /*
         * In the universe of sparcv7, sparcv9, ia32, and amd64 this code can be
         * common: <sys/procfs_isa.h> conveniently #defines R_FP to be the
         * appropriate register we need to set in order to perform a stack
         * traceback from a given frame address.
         */
        if (flags & DCMD_ADDRSPEC) {
                bzero(&gregs, sizeof (gregs));
                gregs.gregs[R_FP] = addr;
#ifdef __sparc
                gregs.gregs[R_I7] = saved_pc;
#endif /* __sparc */
        } else if (PTL_GETREGS(t, PTL_TID(t), gregs.gregs) != 0) {
                mdb_warn("failed to get current register set");
                return (DCMD_ERR);
        }

        (void) mdb_tgt_stack_iter(t, &gregs, func, arg);
        return (DCMD_OK);
}

static int
pt_stack(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        return (pt_stack_common(addr, flags, argc, argv, pt_frame, 0));
}

static int
pt_stackv(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        return (pt_stack_common(addr, flags, argc, argv, pt_framev, 0));
}

static int
pt_stackr(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        /*
         * Force printing of first register window, by setting  the
         * saved pc (%i7) to PC_FAKE.
         */
        return (pt_stack_common(addr, flags, argc, argv, pt_framer, PC_FAKE));
}

/*ARGSUSED*/
static int
pt_ignored(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        struct ps_prochandle *P = mdb.m_target->t_pshandle;
        char buf[PRSIGBUFSZ];

        if ((flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (P == NULL) {
                mdb_warn("no process is currently active\n");
                return (DCMD_ERR);
        }

        mdb_printf("%s\n", proc_sigset2str(&Pstatus(P)->pr_sigtrace, " ",
            FALSE, buf, sizeof (buf)));

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_lwpid(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        struct ps_prochandle *P = mdb.m_target->t_pshandle;

        if ((flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (P == NULL) {
                mdb_warn("no process is currently active\n");
                return (DCMD_ERR);
        }

        mdb_printf("%d\n", Pstatus(P)->pr_lwp.pr_lwpid);
        return (DCMD_OK);
}

static int
pt_print_lwpid(int *n, const lwpstatus_t *psp)
{
        struct ps_prochandle *P = mdb.m_target->t_pshandle;
        int nlwp = Pstatus(P)->pr_nlwp;

        if (*n == nlwp - 2)
                mdb_printf("%d and ", (int)psp->pr_lwpid);
        else if (*n == nlwp - 1)
                mdb_printf("%d are", (int)psp->pr_lwpid);
        else
                mdb_printf("%d, ", (int)psp->pr_lwpid);

        (*n)++;
        return (0);
}

/*ARGSUSED*/
static int
pt_lwpids(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        struct ps_prochandle *P = mdb.m_target->t_pshandle;
        int n = 0;

        if (P == NULL) {
                mdb_warn("no process is currently active\n");
                return (DCMD_ERR);
        }

        switch (Pstatus(P)->pr_nlwp) {
        case 0:
                mdb_printf("no lwps are");
                break;
        case 1:
                mdb_printf("lwpid %d is the only lwp",
                    Pstatus(P)->pr_lwp.pr_lwpid);
                break;
        default:
                mdb_printf("lwpids ");
                (void) Plwp_iter(P, (proc_lwp_f *)pt_print_lwpid, &n);
        }

        switch (Pstate(P)) {
        case PS_DEAD:
                mdb_printf(" in core of process %d.\n", Pstatus(P)->pr_pid);
                break;
        case PS_IDLE:
                mdb_printf(" in idle target.\n");
                break;
        default:
                mdb_printf(" in process %d.\n", (int)Pstatus(P)->pr_pid);
                break;
        }

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_ignore(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        pt_data_t *pt = mdb.m_target->t_data;

        if (!(flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (addr < 1 || addr > pt->p_maxsig) {
                mdb_warn("invalid signal number -- 0t%lu\n", addr);
                return (DCMD_ERR);
        }

        (void) mdb_tgt_vespec_iter(mdb.m_target, pt_ignore_sig, (void *)addr);
        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_attach(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        int state, perr;

        if (!(flags & DCMD_ADDRSPEC) && argc == 0)
                return (DCMD_USAGE);

        if (((flags & DCMD_ADDRSPEC) && argc != 0) || argc > 1 ||
            (argc != 0 && argv->a_type != MDB_TYPE_STRING))
                return (DCMD_USAGE);

        if (t->t_pshandle != NULL && Pstate(t->t_pshandle) != PS_IDLE) {
                mdb_warn("debugger is already attached to a %s\n",
                    (Pstate(t->t_pshandle) == PS_DEAD) ? "core" : "process");
                return (DCMD_ERR);
        }

        if (pt->p_fio == NULL) {
                mdb_warn("attach requires executable to be specified on "
                    "command-line (or use -p)\n");
                return (DCMD_ERR);
        }

        if (flags & DCMD_ADDRSPEC)
                t->t_pshandle = Pgrab((pid_t)addr, pt->p_gflags, &perr);
        else
                t->t_pshandle = proc_arg_grab(argv->a_un.a_str,
                    PR_ARG_ANY, pt->p_gflags, &perr);

        if (t->t_pshandle == NULL) {
                t->t_pshandle = pt->p_idlehandle;
                mdb_warn("cannot attach: %s\n", Pgrab_error(perr));
                return (DCMD_ERR);
        }

        state = Pstate(t->t_pshandle);
        if (state != PS_DEAD && state != PS_IDLE) {
                (void) Punsetflags(t->t_pshandle, PR_KLC);
                (void) Psetflags(t->t_pshandle, PR_RLC);
                pt_post_attach(t);
                pt_activate_common(t);
        }

        (void) mdb_tgt_status(t, &t->t_status);
        mdb_module_load_all(0);
        return (DCMD_OK);
}

static int
pt_regstatus(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;

        if (t->t_pshandle != NULL) {
                const pstatus_t *psp = Pstatus(t->t_pshandle);
                int cursig = psp->pr_lwp.pr_cursig;
                char signame[SIG2STR_MAX];
                int state = Pstate(t->t_pshandle);

                if (state != PS_DEAD && state != PS_IDLE)
                        mdb_printf("process id = %d\n", psp->pr_pid);
                else
                        mdb_printf("no process\n");

                if (cursig != 0 && sig2str(cursig, signame) == 0)
                        mdb_printf("SIG%s: %s\n", signame, strsignal(cursig));
        }

        return (pt_regs(addr, flags, argc, argv));
}

static void
pt_thread_name(mdb_tgt_t *t, mdb_tgt_tid_t tid, char *buf, size_t bufsize)
{
        char name[THREAD_NAME_MAX];

        buf[0] = '\0';

        if (t->t_pshandle == NULL ||
            Plwp_getname(t->t_pshandle, tid, name, sizeof (name)) != 0 ||
            name[0] == '\0') {
                (void) mdb_snprintf(buf, bufsize, "%lu", tid);
                return;
        }

        (void) mdb_snprintf(buf, bufsize, "%lu [%s]", tid, name);
}

static int
pt_findstack(uintptr_t tid, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        mdb_tgt_gregset_t gregs;
        int showargs = 0;
        int count;
        uintptr_t pc, sp;
        char name[128];

        if (!(flags & DCMD_ADDRSPEC))
                return (DCMD_USAGE);

        count = mdb_getopts(argc, argv, 'v', MDB_OPT_SETBITS, TRUE, &showargs,
            NULL);
        argc -= count;
        argv += count;

        if (argc > 1 || (argc == 1 && argv->a_type != MDB_TYPE_STRING))
                return (DCMD_USAGE);

        if (PTL_GETREGS(t, tid, gregs.gregs) != 0) {
                mdb_warn("failed to get register set for thread %p", tid);
                return (DCMD_ERR);
        }

        pc = gregs.gregs[R_PC];
#if defined(__i386) || defined(__amd64)
        sp = gregs.gregs[R_FP];
#else
        sp = gregs.gregs[R_SP];
#endif

        pt_thread_name(t, tid, name, sizeof (name));

        mdb_printf("stack pointer for thread %s: %p\n", name, sp);
        if (pc != 0)
                mdb_printf("[ %0?lr %a() ]\n", sp, pc);

        (void) mdb_inc_indent(2);
        mdb_set_dot(sp);

        if (argc == 1)
                (void) mdb_eval(argv->a_un.a_str);
        else if (showargs)
                (void) mdb_eval("<.$C");
        else
                (void) mdb_eval("<.$C0");

        (void) mdb_dec_indent(2);
        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_gcore(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        char *prefix = "core";
        char *content_str = NULL;
        core_content_t content = CC_CONTENT_DEFAULT;
        size_t size;
        char *fname;
        pid_t pid;

        if (flags & DCMD_ADDRSPEC)
                return (DCMD_USAGE);

        if (mdb_getopts(argc, argv,
            'o', MDB_OPT_STR, &prefix,
            'c', MDB_OPT_STR, &content_str, NULL) != argc)
                return (DCMD_USAGE);

        if (content_str != NULL &&
            (proc_str2content(content_str, &content) != 0 ||
            content == CC_CONTENT_INVALID)) {
                mdb_warn("invalid content string '%s'\n", content_str);
                return (DCMD_ERR);
        }

        if (t->t_pshandle == NULL) {
                mdb_warn("no process active\n");
                return (DCMD_ERR);
        }

        pid = Pstatus(t->t_pshandle)->pr_pid;
        size = 1 + mdb_snprintf(NULL, 0, "%s.%d", prefix, (int)pid);
        fname = mdb_alloc(size, UM_SLEEP | UM_GC);
        (void) mdb_snprintf(fname, size, "%s.%d", prefix, (int)pid);

        if (Pgcore(t->t_pshandle, fname, content) != 0) {
                /*
                 * Short writes during dumping are specifically described by
                 * EBADE, just as ZFS uses this otherwise-unused code for
                 * checksum errors.  Translate to and mdb errno.
                 */
                if (errno == EBADE)
                        (void) set_errno(EMDB_SHORTWRITE);
                mdb_warn("couldn't dump core");
                return (DCMD_ERR);
        }

        mdb_warn("%s dumped\n", fname);

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_kill(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        int state;

        if ((flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (t->t_pshandle != NULL &&
            (state = Pstate(t->t_pshandle)) != PS_DEAD && state != PS_IDLE) {
                mdb_warn("victim process PID %d forcibly terminated\n",
                    (int)Pstatus(t->t_pshandle)->pr_pid);
                pt_pre_detach(t, TRUE);
                pt_release_parents(t);
                Prelease(t->t_pshandle, PRELEASE_KILL);
                t->t_pshandle = pt->p_idlehandle;
                (void) mdb_tgt_status(t, &t->t_status);
                mdb.m_flags &= ~(MDB_FL_VCREATE | MDB_FL_JOBCTL);
        } else
                mdb_warn("no victim process is currently under control\n");

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_detach(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        int rflags = pt->p_rflags;

        if (argc != 0 && argv->a_type == MDB_TYPE_STRING &&
            strcmp(argv->a_un.a_str, "-a") == 0) {
                rflags = PRELEASE_HANG | PRELEASE_CLEAR;
                argv++;
                argc--;
        }

        if ((flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (t->t_pshandle == NULL || Pstate(t->t_pshandle) == PS_IDLE) {
                mdb_warn("debugger is not currently attached to a process "
                    "or core file\n");
                return (DCMD_ERR);
        }

        pt_pre_detach(t, TRUE);
        pt_release_parents(t);
        Prelease(t->t_pshandle, rflags);
        t->t_pshandle = pt->p_idlehandle;
        (void) mdb_tgt_status(t, &t->t_status);
        mdb.m_flags &= ~(MDB_FL_VCREATE | MDB_FL_JOBCTL);

        return (DCMD_OK);
}

static uintmax_t
reg_disc_get(const mdb_var_t *v)
{
        mdb_tgt_t *t = MDB_NV_COOKIE(v);
        mdb_tgt_tid_t tid = PTL_TID(t);
        mdb_tgt_reg_t r = 0;

        if (tid != (mdb_tgt_tid_t)-1L)
                (void) mdb_tgt_getareg(t, tid, mdb_nv_get_name(v), &r);

        return (r);
}

static void
reg_disc_set(mdb_var_t *v, uintmax_t r)
{
        mdb_tgt_t *t = MDB_NV_COOKIE(v);
        mdb_tgt_tid_t tid = PTL_TID(t);

        if (tid != (mdb_tgt_tid_t)-1L && mdb_tgt_putareg(t, tid,
            mdb_nv_get_name(v), r) == -1)
                mdb_warn("failed to modify %%%s register", mdb_nv_get_name(v));
}

static void
pt_print_reason(const lwpstatus_t *psp)
{
        char name[SIG2STR_MAX + 4]; /* enough for SIG+name+\0, syscall or flt */
        const char *desc;

        switch (psp->pr_why) {
        case PR_REQUESTED:
                mdb_printf("stopped by debugger");
                break;
        case PR_SIGNALLED:
                mdb_printf("stopped on %s (%s)", proc_signame(psp->pr_what,
                    name, sizeof (name)), strsignal(psp->pr_what));
                break;
        case PR_SYSENTRY:
                mdb_printf("stopped on entry to %s system call",
                    proc_sysname(psp->pr_what, name, sizeof (name)));
                break;
        case PR_SYSEXIT:
                mdb_printf("stopped on exit from %s system call",
                    proc_sysname(psp->pr_what, name, sizeof (name)));
                break;
        case PR_JOBCONTROL:
                mdb_printf("stopped by job control");
                break;
        case PR_FAULTED:
                if (psp->pr_what == FLTBPT) {
                        mdb_printf("stopped on a breakpoint");
                } else if (psp->pr_what == FLTWATCH) {
                        switch (psp->pr_info.si_code) {
                        case TRAP_RWATCH:
                                desc = "read";
                                break;
                        case TRAP_WWATCH:
                                desc = "write";
                                break;
                        case TRAP_XWATCH:
                                desc = "execute";
                                break;
                        default:
                                desc = "unknown";
                        }
                        mdb_printf("stopped %s a watchpoint (%s access to %p)",
                            psp->pr_info.si_trapafter ? "after" : "on",
                            desc, psp->pr_info.si_addr);
                } else if (psp->pr_what == FLTTRACE) {
                        mdb_printf("stopped after a single-step");
                } else {
                        mdb_printf("stopped on a %s fault",
                            proc_fltname(psp->pr_what, name, sizeof (name)));
                }
                break;
        case PR_SUSPENDED:
        case PR_CHECKPOINT:
                mdb_printf("suspended by the kernel");
                break;
        default:
                mdb_printf("stopped for unknown reason (%d/%d)",
                    psp->pr_why, psp->pr_what);
        }
}

/*ARGSUSED*/
static int
pt_status_dcmd(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;

        if (P != NULL) {
                const psinfo_t *pip = Ppsinfo(P);
                const pstatus_t *psp = Pstatus(P);
                int cursig = 0, bits = 0, coredump = 0;
                int state;
                GElf_Sym sym;
                uintptr_t panicstr;
                char *panicbuf = mdb_alloc(PANIC_BUFSIZE, UM_SLEEP);
                const siginfo_t *sip = &(psp->pr_lwp.pr_info);

                char execname[MAXPATHLEN], buf[BUFSIZ];
                char signame[SIG2STR_MAX + 4]; /* enough for SIG+name+\0 */

                mdb_tgt_spec_desc_t desc;
                mdb_sespec_t *sep;

                struct utsname uts;
                prcred_t cred;
                psinfo_t pi;

                (void) strcpy(uts.nodename, "unknown machine");
                (void) Puname(P, &uts);

                if (pip != NULL) {
                        bcopy(pip, &pi, sizeof (psinfo_t));
                        proc_unctrl_psinfo(&pi);
                } else
                        bzero(&pi, sizeof (psinfo_t));

                bits = pi.pr_dmodel == PR_MODEL_ILP32 ? 32 : 64;

                state = Pstate(P);
                if (psp != NULL && state != PS_UNDEAD && state != PS_IDLE)
                        cursig = psp->pr_lwp.pr_cursig;

                if (state == PS_DEAD && pip != NULL) {
                        mdb_printf("debugging core file of %s (%d-bit) "
                            "from %s\n", pi.pr_fname, bits, uts.nodename);

                } else if (state == PS_DEAD) {
                        mdb_printf("debugging core file\n");

                } else if (state == PS_IDLE) {
                        const GElf_Ehdr *ehp = &pt->p_file->gf_ehdr;

                        mdb_printf("debugging %s file (%d-bit)\n",
                            ehp->e_type == ET_EXEC ? "executable" : "object",
                            ehp->e_ident[EI_CLASS] == ELFCLASS32 ? 32 : 64);

                } else if (state == PS_UNDEAD && pi.pr_pid == 0) {
                        mdb_printf("debugging defunct process\n");

                } else {
                        mdb_printf("debugging PID %d (%d-bit)\n",
                            pi.pr_pid, bits);
                }

                if (Pexecname(P, execname, sizeof (execname)) != NULL)
                        mdb_printf("file: %s\n", execname);

                if (pip != NULL && state == PS_DEAD)
                        mdb_printf("initial argv: %s\n", pi.pr_psargs);

                if (state != PS_UNDEAD && state != PS_IDLE) {
                        mdb_printf("threading model: ");
                        if (pt->p_ptl_ops == &proc_lwp_ops)
                                mdb_printf("raw lwps\n");
                        else
                                mdb_printf("native threads\n");
                }

                mdb_printf("status: ");
                switch (state) {
                case PS_RUN:
                        ASSERT(!(psp->pr_flags & PR_STOPPED));
                        mdb_printf("process is running");
                        if (psp->pr_flags & PR_DSTOP)
                                mdb_printf(", debugger stop directive pending");
                        mdb_printf("\n");
                        break;

                case PS_STOP:
                        ASSERT(psp->pr_flags & PR_STOPPED);
                        pt_print_reason(&psp->pr_lwp);

                        if (psp->pr_flags & PR_DSTOP)
                                mdb_printf(", debugger stop directive pending");
                        if (psp->pr_flags & PR_ASLEEP)
                                mdb_printf(", sleeping in %s system call",
                                    proc_sysname(psp->pr_lwp.pr_syscall,
                                    signame, sizeof (signame)));

                        mdb_printf("\n");

                        for (sep = t->t_matched; sep != T_SE_END;
                            sep = sep->se_matched) {
                                mdb_printf("event: %s\n", sep->se_ops->se_info(
                                    t, sep, mdb_list_next(&sep->se_velist),
                                    &desc, buf, sizeof (buf)));
                        }
                        break;

                case PS_LOST:
                        mdb_printf("debugger lost control of process\n");
                        break;

                case PS_UNDEAD:
                        coredump = WIFSIGNALED(pi.pr_wstat) &&
                            WCOREDUMP(pi.pr_wstat);
                        /*FALLTHRU*/

                case PS_DEAD:
                        if (cursig == 0 && WIFSIGNALED(pi.pr_wstat))
                                cursig = WTERMSIG(pi.pr_wstat);
                        /*
                         * We can only use pr_wstat == 0 as a test for gcore if
                         * an NT_PRCRED note is present; these features were
                         * added at the same time in Solaris 8.
                         */
                        if (pi.pr_wstat == 0 && Pstate(P) == PS_DEAD &&
                            Pcred(P, &cred, 1) == 0) {
                                mdb_printf("process core file generated "
                                    "with gcore(1)\n");
                        } else if (cursig != 0) {
                                mdb_printf("process terminated by %s (%s)",
                                    proc_signame(cursig, signame,
                                    sizeof (signame)), strsignal(cursig));

                                if (sip->si_signo != 0 && SI_FROMUSER(sip) &&
                                    sip->si_pid != 0) {
                                        mdb_printf(", pid=%d uid=%u",
                                            (int)sip->si_pid, sip->si_uid);
                                        if (sip->si_code != 0) {
                                                mdb_printf(" code=%d",
                                                    sip->si_code);
                                        }
                                } else {
                                        switch (sip->si_signo) {
                                        case SIGILL:
                                        case SIGTRAP:
                                        case SIGFPE:
                                        case SIGSEGV:
                                        case SIGBUS:
                                        case SIGEMT:
                                                mdb_printf(", addr=%p",
                                                    sip->si_addr);
                                        default:
                                                break;
                                        }
                                }

                                if (coredump)
                                        mdb_printf(" - core file dumped");
                                mdb_printf("\n");
                        } else {
                                mdb_printf("process terminated with exit "
                                    "status %d\n", WEXITSTATUS(pi.pr_wstat));
                        }

                        if (Plookup_by_name(t->t_pshandle, "libc.so",
                            "panicstr", &sym) == 0 &&
                            Pread(t->t_pshandle, &panicstr, sizeof (panicstr),
                            sym.st_value) == sizeof (panicstr) &&
                            Pread_string(t->t_pshandle, panicbuf,
                            PANIC_BUFSIZE, panicstr) > 0) {
                                mdb_printf("panic message: %s",
                                    panicbuf);
                        }


                        break;

                case PS_IDLE:
                        mdb_printf("idle\n");
                        break;

                default:
                        mdb_printf("unknown libproc Pstate: %d\n", Pstate(P));
                }
                mdb_free(panicbuf, PANIC_BUFSIZE);

        } else if (pt->p_file != NULL) {
                const GElf_Ehdr *ehp = &pt->p_file->gf_ehdr;

                mdb_printf("debugging %s file (%d-bit)\n",
                    ehp->e_type == ET_EXEC ? "executable" : "object",
                    ehp->e_ident[EI_CLASS] == ELFCLASS32 ? 32 : 64);
                mdb_printf("executable file: %s\n", IOP_NAME(pt->p_fio));
                mdb_printf("status: idle\n");
        }

        return (DCMD_OK);
}

static int
pt_tls(uintptr_t tid, uint_t flags, int argc, const mdb_arg_t *argv)
{
        const char *name;
        const char *object;
        GElf_Sym sym;
        mdb_syminfo_t si;
        mdb_tgt_t *t = mdb.m_target;

        if (!(flags & DCMD_ADDRSPEC) || argc > 1)
                return (DCMD_USAGE);

        if (argc == 0) {
                psaddr_t b;

                if (tlsbase(t, tid, PR_LMID_EVERY, MDB_TGT_OBJ_EXEC, &b) != 0) {
                        mdb_warn("failed to lookup tlsbase for %r", tid);
                        return (DCMD_ERR);
                }

                mdb_printf("%lr\n", b);
                mdb_set_dot(b);

                return (DCMD_OK);
        }

        name = argv[0].a_un.a_str;
        object = MDB_TGT_OBJ_EVERY;

        if (pt_lookup_by_name_thr(t, object, name, &sym, &si, tid) != 0) {
                mdb_warn("failed to lookup %s", name);
                return (DCMD_ABORT); /* avoid repeated failure */
        }

        if (GELF_ST_TYPE(sym.st_info) != STT_TLS && DCMD_HDRSPEC(flags))
                mdb_warn("%s does not refer to thread local storage\n", name);

        mdb_printf("%llr\n", sym.st_value);
        mdb_set_dot(sym.st_value);

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_tmodel(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        const pt_ptl_ops_t *ptl_ops;

        if (argc != 1 || argv->a_type != MDB_TYPE_STRING)
                return (DCMD_USAGE);

        if (strcmp(argv->a_un.a_str, "thread") == 0)
                ptl_ops = &proc_tdb_ops;
        else if (strcmp(argv->a_un.a_str, "lwp") == 0)
                ptl_ops = &proc_lwp_ops;
        else
                return (DCMD_USAGE);

        if (t->t_pshandle != NULL && pt->p_ptl_ops != ptl_ops) {
                PTL_DTOR(t);
                pt->p_tdb_ops = NULL;
                pt->p_ptl_ops = &proc_lwp_ops;
                pt->p_ptl_hdl = NULL;

                if (ptl_ops == &proc_tdb_ops) {
                        (void) Pobject_iter(t->t_pshandle, (proc_map_f *)
                            thr_check, t);
                }
        }

        (void) mdb_tgt_status(t, &t->t_status);
        return (DCMD_OK);
}

static const char *
env_match(const char *cmp, const char *nameval)
{
        const char *loc;
        size_t cmplen = strlen(cmp);

        loc = strchr(nameval, '=');
        if (loc != NULL && (loc - nameval) == cmplen &&
            strncmp(nameval, cmp, cmplen) == 0) {
                return (loc + 1);
        }

        return (NULL);
}

/*ARGSUSED*/
static int
print_env(void *data, struct ps_prochandle *P, uintptr_t addr,
    const char *nameval)
{
        const char *value;

        if (nameval == NULL) {
                mdb_printf("<0x%p>\n", addr);
        } else {
                if (data == NULL)
                        mdb_printf("%s\n", nameval);
                else if ((value = env_match(data, nameval)) != NULL)
                        mdb_printf("%s\n", value);
        }

        return (0);
}

/*ARGSUSED*/
static int
pt_getenv(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        int i;
        uint_t opt_t = 0;
        mdb_var_t *v;

        i = mdb_getopts(argc, argv,
            't', MDB_OPT_SETBITS, TRUE, &opt_t, NULL);

        argc -= i;
        argv += i;

        if ((flags & DCMD_ADDRSPEC) || argc > 1)
                return (DCMD_USAGE);

        if (argc == 1 && argv->a_type != MDB_TYPE_STRING)
                return (DCMD_USAGE);

        if (opt_t && t->t_pshandle == NULL) {
                mdb_warn("no process active\n");
                return (DCMD_ERR);
        }

        if (opt_t && (Pstate(t->t_pshandle) == PS_IDLE ||
            Pstate(t->t_pshandle) == PS_UNDEAD)) {
                mdb_warn("-t option requires target to be running\n");
                return (DCMD_ERR);
        }

        if (opt_t != 0) {
                if (Penv_iter(t->t_pshandle, print_env,
                    argc == 0 ? NULL : (void *)argv->a_un.a_str) != 0)
                        return (DCMD_ERR);
        } else if (argc == 1) {
                if ((v = mdb_nv_lookup(&pt->p_env, argv->a_un.a_str)) == NULL)
                        return (DCMD_ERR);

                ASSERT(strchr(mdb_nv_get_cookie(v), '=') != NULL);
                mdb_printf("%s\n", strchr(mdb_nv_get_cookie(v), '=') + 1);
        } else {

                mdb_nv_rewind(&pt->p_env);
                while ((v = mdb_nv_advance(&pt->p_env)) != NULL)
                        mdb_printf("%s\n", mdb_nv_get_cookie(v));
        }

        return (DCMD_OK);
}

/*
 * Function to set a variable in the internal environment, which is used when
 * creating new processes.  Note that it is possible that 'nameval' can refer to
 * read-only memory, if mdb calls putenv() on an existing value before calling
 * this function.  While we should avoid this situation, this function is
 * designed to be robust in the face of such changes.
 */
static void
pt_env_set(pt_data_t *pt, const char *nameval)
{
        mdb_var_t *v;
        char *equals, *val;
        const char *name;
        size_t len;

        if ((equals = strchr(nameval, '=')) != NULL) {
                val = strdup(nameval);
                equals = val + (equals - nameval);
        } else {
                /*
                 * nameval doesn't contain an equals character.  Convert this to
                 * be 'nameval='.
                 */
                len = strlen(nameval);
                val = mdb_alloc(len + 2, UM_SLEEP);
                (void) mdb_snprintf(val, len + 2, "%s=", nameval);
                equals = val + len;
        }

        /* temporary truncate the string for lookup/insert */
        *equals = '\0';
        v = mdb_nv_lookup(&pt->p_env, val);

        if (v != NULL) {
                char *old = mdb_nv_get_cookie(v);
                mdb_free(old, strlen(old) + 1);
                name = mdb_nv_get_name(v);
        } else {
                /*
                 * The environment is created using MDB_NV_EXTNAME, so we must
                 * provide external storage for the variable names.
                 */
                name = strdup(val);
        }

        *equals = '=';

        (void) mdb_nv_insert(&pt->p_env, name, NULL, (uintptr_t)val,
            MDB_NV_EXTNAME);

        if (equals)
                *equals = '=';
}

/*
 * Clears the internal environment.
 */
static void
pt_env_clear(pt_data_t *pt)
{
        mdb_var_t *v;
        char *val, *name;

        mdb_nv_rewind(&pt->p_env);
        while ((v = mdb_nv_advance(&pt->p_env)) != NULL) {

                name = (char *)mdb_nv_get_name(v);
                val = mdb_nv_get_cookie(v);

                mdb_nv_remove(&pt->p_env, v);

                mdb_free(name, strlen(name) + 1);
                mdb_free(val, strlen(val) + 1);
        }
}

/*ARGSUSED*/
static int
pt_setenv(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        char *nameval;
        size_t len;
        int alloc;

        if ((flags & DCMD_ADDRSPEC) || argc == 0 || argc > 2)
                return (DCMD_USAGE);

        if ((argc > 0 && argv[0].a_type != MDB_TYPE_STRING) ||
            (argc > 1 && argv[1].a_type != MDB_TYPE_STRING))
                return (DCMD_USAGE);

        if (t->t_pshandle == NULL) {
                mdb_warn("no process active\n");
                return (DCMD_ERR);
        }

        /*
         * If the process is in some sort of running state, warn the user that
         * changes won't immediately take effect.
         */
        if (Pstate(t->t_pshandle) == PS_RUN ||
            Pstate(t->t_pshandle) == PS_STOP) {
                mdb_warn("warning: changes will not take effect until process"
                    " is restarted\n");
        }

        /*
         * We allow two forms of operation.  The first is the usual "name=value"
         * parameter.  We also allow the user to specify two arguments, where
         * the first is the name of the variable, and the second is the value.
         */
        alloc = 0;
        if (argc == 1) {
                nameval = (char *)argv->a_un.a_str;
        } else {
                len = strlen(argv[0].a_un.a_str) +
                    strlen(argv[1].a_un.a_str) + 2;
                nameval = mdb_alloc(len, UM_SLEEP);
                (void) mdb_snprintf(nameval, len, "%s=%s", argv[0].a_un.a_str,
                    argv[1].a_un.a_str);
                alloc = 1;
        }

        pt_env_set(pt, nameval);

        if (alloc)
                mdb_free(nameval, strlen(nameval) + 1);

        return (DCMD_OK);
}

/*ARGSUSED*/
static int
pt_unsetenv(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        mdb_tgt_t *t = mdb.m_target;
        pt_data_t *pt = t->t_data;
        mdb_var_t *v;
        char *value, *name;

        if ((flags & DCMD_ADDRSPEC) || argc > 1)
                return (DCMD_USAGE);

        if (argc == 1 && argv->a_type != MDB_TYPE_STRING)
                return (DCMD_USAGE);

        if (t->t_pshandle == NULL) {
                mdb_warn("no process active\n");
                return (DCMD_ERR);
        }

        /*
         * If the process is in some sort of running state, warn the user that
         * changes won't immediately take effect.
         */
        if (Pstate(t->t_pshandle) == PS_RUN ||
            Pstate(t->t_pshandle) == PS_STOP) {
                mdb_warn("warning: changes will not take effect until process"
                    " is restarted\n");
        }

        if (argc == 0) {
                pt_env_clear(pt);
        } else {
                if ((v = mdb_nv_lookup(&pt->p_env, argv->a_un.a_str)) != NULL) {
                        name = (char *)mdb_nv_get_name(v);
                        value = mdb_nv_get_cookie(v);

                        mdb_nv_remove(&pt->p_env, v);

                        mdb_free(name, strlen(name) + 1);
                        mdb_free(value, strlen(value) + 1);
                }
        }

        return (DCMD_OK);
}

void
getenv_help(void)
{
        mdb_printf("-t  show current process environment"
            " instead of initial environment.\n");
}

static const mdb_dcmd_t pt_dcmds[] = {
        { "$c", "?[cnt]", "print stack backtrace", pt_stack },
        { "$C", "?[cnt]", "print stack backtrace", pt_stackv },
        { "$i", NULL, "print signals that are ignored", pt_ignored },
        { "$l", NULL, "print the representative thread's lwp id", pt_lwpid },
        { "$L", NULL, "print list of the active lwp ids", pt_lwpids },
        { "$r", "?[-u]", "print general-purpose registers", pt_regs },
        { "$x", "?", "print floating point registers", pt_fpregs },
        { "$X", "?", "print floating point registers", pt_fpregs },
        { "$y", "?", "print floating point registers", pt_fpregs },
        { "$Y", "?", "print floating point registers", pt_fpregs },
        { "$?", "?", "print status and registers", pt_regstatus },
        { ":A", "?[core|pid]", "attach to process or core file", pt_attach },
        { ":i", ":", "ignore signal (delete all matching events)", pt_ignore },
        { ":k", NULL, "forcibly kill and release target", pt_kill },
        { ":R", "[-a]", "release the previously attached process", pt_detach },
        { "attach", "?[core|pid]",
            "attach to process or core file", pt_attach },
        { "findstack", ":[-v]", "find user thread stack", pt_findstack },
        { "gcore", "[-o prefix] [-c content]",
            "produce a core file for the attached process", pt_gcore },
        { "getenv", "[-t] [name]", "display an environment variable",
                pt_getenv, getenv_help },
        { "kill", NULL, "forcibly kill and release target", pt_kill },
        { "release", "[-a]",
            "release the previously attached process", pt_detach },
        { "regs", "?[-u]", "print general-purpose registers", pt_regs },
        { "fpregs", "?[-dqs]", "print floating point registers", pt_fpregs },
        { "setenv", "name=value", "set an environment variable", pt_setenv },
        { "stack", "?[cnt]", "print stack backtrace", pt_stack },
        { "stackregs", "?", "print stack backtrace and registers", pt_stackr },
        { "status", NULL, "print summary of current target", pt_status_dcmd },
        { "tls", ":symbol",
            "lookup TLS data in the context of a given thread", pt_tls },
        { "tmodel", "{thread|lwp}", NULL, pt_tmodel },
        { "unsetenv", "[name]", "clear an environment variable", pt_unsetenv },
        { NULL }
};

static void
pt_thr_walk_fini(mdb_walk_state_t *wsp)
{
        mdb_addrvec_destroy(wsp->walk_data);
        mdb_free(wsp->walk_data, sizeof (mdb_addrvec_t));
}

static int
pt_thr_walk_init(mdb_walk_state_t *wsp)
{
        wsp->walk_data = mdb_zalloc(sizeof (mdb_addrvec_t), UM_SLEEP);
        mdb_addrvec_create(wsp->walk_data);

        if (PTL_ITER(mdb.m_target, wsp->walk_data) == -1) {
                mdb_warn("failed to iterate over threads");
                pt_thr_walk_fini(wsp);
                return (WALK_ERR);
        }

        return (WALK_NEXT);
}

static int
pt_thr_walk_step(mdb_walk_state_t *wsp)
{
        if (mdb_addrvec_length(wsp->walk_data) != 0) {
                return (wsp->walk_callback(mdb_addrvec_shift(wsp->walk_data),
                    NULL, wsp->walk_cbdata));
        }
        return (WALK_DONE);
}

static const mdb_walker_t pt_walkers[] = {
        { "thread", "walk list of valid thread identifiers",
            pt_thr_walk_init, pt_thr_walk_step, pt_thr_walk_fini },
        { NULL }
};

static int
pt_agent_check(boolean_t *agent, const lwpstatus_t *psp)
{
        if (psp->pr_flags & PR_AGENT)
                *agent = B_TRUE;

        return (0);
}

static void
pt_activate_common(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;
        boolean_t hasagent = B_FALSE;
        GElf_Sym sym;

        /*
         * If we have a libproc handle and AT_BASE is set, the process or core
         * is dynamically linked.  We call Prd_agent() to force libproc to
         * try to initialize librtld_db, and issue a warning if that fails.
         */
        if (t->t_pshandle != NULL && Pgetauxval(t->t_pshandle,
            AT_BASE) != -1L && Prd_agent(t->t_pshandle) == NULL) {
                mdb_warn("warning: librtld_db failed to initialize; shared "
                    "library information will not be available\n");
        }

        if (t->t_pshandle != NULL) {
                (void) Plwp_iter(t->t_pshandle,
                    (proc_lwp_f *)pt_agent_check, &hasagent);
        }

        if (hasagent) {
                mdb_warn("agent lwp detected; forcing "
                    "lwp thread model (use ::tmodel to change)\n");
        } else if (t->t_pshandle != NULL && Pstate(t->t_pshandle) != PS_IDLE) {
                /*
                 * If we have a libproc handle and we do not have an agent LWP,
                 * look for the correct thread debugging library.  (If we have
                 * an agent LWP, we leave the model as the raw LWP model to
                 * allow the agent LWP to be visible to the debugger.)
                 */
                (void) Pobject_iter(t->t_pshandle, (proc_map_f *)thr_check, t);
        }

        /*
         * If there's a global object named '_mdb_abort_info', assuming we're
         * debugging mdb itself and load the developer support module.
         */
        if (mdb_gelf_symtab_lookup_by_name(pt->p_symtab, "_mdb_abort_info",
            &sym, NULL) == 0 && GELF_ST_TYPE(sym.st_info) == STT_OBJECT) {
                if (mdb_module_load("mdb_ds", MDB_MOD_SILENT) < 0)
                        mdb_warn("warning: failed to load developer support\n");
        }

        mdb_tgt_elf_export(pt->p_file);
}

static void
pt_activate(mdb_tgt_t *t)
{
        static const mdb_nv_disc_t reg_disc = { reg_disc_set, reg_disc_get };

        pt_data_t *pt = t->t_data;
        struct utsname u1, u2;
        mdb_var_t *v;
        core_content_t content;

        if (t->t_pshandle) {
                mdb_prop_postmortem = (Pstate(t->t_pshandle) == PS_DEAD);
                mdb_prop_kernel = FALSE;
        } else
                mdb_prop_kernel = mdb_prop_postmortem = FALSE;

        mdb_prop_datamodel = MDB_TGT_MODEL_NATIVE;

        /*
         * If we're examining a core file that doesn't contain program text,
         * and uname(2) doesn't match the NT_UTSNAME note recorded in the
         * core file, issue a warning.
         */
        if (mdb_prop_postmortem == TRUE &&
            ((content = Pcontent(t->t_pshandle)) == CC_CONTENT_INVALID ||
            !(content & CC_CONTENT_TEXT)) &&
            uname(&u1) >= 0 && Puname(t->t_pshandle, &u2) == 0 &&
            (strcmp(u1.release, u2.release) != 0 ||
            strcmp(u1.version, u2.version) != 0)) {
                mdb_warn("warning: core file is from %s %s %s; shared text "
                    "mappings may not match installed libraries\n",
                    u2.sysname, u2.release, u2.version);
        }

        /*
         * Perform the common initialization tasks -- these are shared with
         * the pt_exec() and pt_run() subroutines.
         */
        pt_activate_common(t);

        (void) mdb_tgt_register_dcmds(t, &pt_dcmds[0], MDB_MOD_FORCE);
        (void) mdb_tgt_register_walkers(t, &pt_walkers[0], MDB_MOD_FORCE);

        /*
         * Iterate through our register description list and export
         * each register as a named variable.
         */
        mdb_nv_rewind(&pt->p_regs);
        while ((v = mdb_nv_advance(&pt->p_regs)) != NULL) {
                ushort_t rd_flags = MDB_TGT_R_FLAGS(mdb_nv_get_value(v));

                if (!(rd_flags & MDB_TGT_R_EXPORT))
                        continue; /* Don't export register as a variable */

                (void) mdb_nv_insert(&mdb.m_nv, mdb_nv_get_name(v), &reg_disc,
                    (uintptr_t)t, MDB_NV_PERSIST);
        }
}

static void
pt_deactivate(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;
        const mdb_dcmd_t *dcp;
        const mdb_walker_t *wp;
        mdb_var_t *v, *w;

        mdb_nv_rewind(&pt->p_regs);
        while ((v = mdb_nv_advance(&pt->p_regs)) != NULL) {
                ushort_t rd_flags = MDB_TGT_R_FLAGS(mdb_nv_get_value(v));

                if (!(rd_flags & MDB_TGT_R_EXPORT))
                        continue; /* Didn't export register as a variable */

                if (w = mdb_nv_lookup(&mdb.m_nv, mdb_nv_get_name(v))) {
                        w->v_flags &= ~MDB_NV_PERSIST;
                        mdb_nv_remove(&mdb.m_nv, w);
                }
        }

        for (wp = &pt_walkers[0]; wp->walk_name != NULL; wp++) {
                if (mdb_module_remove_walker(t->t_module, wp->walk_name) == -1)
                        warn("failed to remove walk %s", wp->walk_name);
        }

        for (dcp = &pt_dcmds[0]; dcp->dc_name != NULL; dcp++) {
                if (mdb_module_remove_dcmd(t->t_module, dcp->dc_name) == -1)
                        warn("failed to remove dcmd %s", dcp->dc_name);
        }

        mdb_prop_postmortem = FALSE;
        mdb_prop_kernel = FALSE;
        mdb_prop_datamodel = MDB_TGT_MODEL_UNKNOWN;
}

static void
pt_periodic(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;

        if (pt->p_rdstate == PT_RD_CONSIST) {
                if (t->t_pshandle != NULL && Pstate(t->t_pshandle) < PS_LOST &&
                    !(mdb.m_flags & MDB_FL_NOMODS)) {
                        mdb_printf("%s: You've got symbols!\n", mdb.m_pname);
                        mdb_module_load_all(0);
                }
                pt->p_rdstate = PT_RD_NONE;
        }
}

static void
pt_destroy(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;

        if (pt->p_idlehandle != NULL && pt->p_idlehandle != t->t_pshandle)
                Prelease(pt->p_idlehandle, 0);

        if (t->t_pshandle != NULL) {
                PTL_DTOR(t);
                pt_release_parents(t);
                pt_pre_detach(t, TRUE);
                Prelease(t->t_pshandle, pt->p_rflags);
        }

        mdb.m_flags &= ~(MDB_FL_VCREATE | MDB_FL_JOBCTL);
        pt_close_aout(t);

        if (pt->p_aout_fio != NULL)
                mdb_io_rele(pt->p_aout_fio);

        pt_env_clear(pt);
        mdb_nv_destroy(&pt->p_env);

        mdb_nv_destroy(&pt->p_regs);
        mdb_free(pt, sizeof (pt_data_t));
}

/*ARGSUSED*/
static const char *
pt_name(mdb_tgt_t *t)
{
        return ("proc");
}

static const char *
pt_platform(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;

        if (t->t_pshandle != NULL &&
            Pplatform(t->t_pshandle, pt->p_platform, MAXNAMELEN) != NULL)
                return (pt->p_platform);

        return (mdb_conf_platform());
}

static int
pt_uname(mdb_tgt_t *t, struct utsname *utsp)
{
        if (t->t_pshandle != NULL)
                return (Puname(t->t_pshandle, utsp));

        return (uname(utsp) >= 0 ? 0 : -1);
}

static int
pt_dmodel(mdb_tgt_t *t)
{
        if (t->t_pshandle == NULL)
                return (MDB_TGT_MODEL_NATIVE);

        switch (Pstatus(t->t_pshandle)->pr_dmodel) {
        case PR_MODEL_ILP32:
                return (MDB_TGT_MODEL_ILP32);
        case PR_MODEL_LP64:
                return (MDB_TGT_MODEL_LP64);
        }

        return (MDB_TGT_MODEL_UNKNOWN);
}

static ssize_t
pt_vread(mdb_tgt_t *t, void *buf, size_t nbytes, uintptr_t addr)
{
        ssize_t n;

        /*
         * If no handle is open yet, reads from virtual addresses are
         * allowed to succeed but return zero-filled memory.
         */
        if (t->t_pshandle == NULL) {
                bzero(buf, nbytes);
                return (nbytes);
        }

        if ((n = Pread(t->t_pshandle, buf, nbytes, addr)) <= 0)
                return (set_errno(EMDB_NOMAP));

        return (n);
}

static ssize_t
pt_vwrite(mdb_tgt_t *t, const void *buf, size_t nbytes, uintptr_t addr)
{
        ssize_t n;

        /*
         * If no handle is open yet, writes to virtual addresses are
         * allowed to succeed but do not actually modify anything.
         */
        if (t->t_pshandle == NULL)
                return (nbytes);

        n = Pwrite(t->t_pshandle, buf, nbytes, addr);

        if (n == -1 && errno == EIO)
                return (set_errno(EMDB_NOMAP));

        return (n);
}

static ssize_t
pt_fread(mdb_tgt_t *t, void *buf, size_t nbytes, uintptr_t addr)
{
        pt_data_t *pt = t->t_data;

        if (pt->p_file != NULL) {
                return (mdb_gelf_rw(pt->p_file, buf, nbytes, addr,
                    IOPF_READ(pt->p_fio), GIO_READ));
        }

        bzero(buf, nbytes);
        return (nbytes);
}

static ssize_t
pt_fwrite(mdb_tgt_t *t, const void *buf, size_t nbytes, uintptr_t addr)
{
        pt_data_t *pt = t->t_data;

        if (pt->p_file != NULL) {
                return (mdb_gelf_rw(pt->p_file, (void *)buf, nbytes, addr,
                    IOPF_WRITE(pt->p_fio), GIO_WRITE));
        }

        return (nbytes);
}

static const char *
pt_resolve_lmid(const char *object, Lmid_t *lmidp)
{
        Lmid_t lmid = PR_LMID_EVERY;
        const char *p;

        if (object == MDB_TGT_OBJ_EVERY || object == MDB_TGT_OBJ_EXEC)
                lmid = LM_ID_BASE; /* restrict scope to a.out's link map */
        else if (object != MDB_TGT_OBJ_RTLD && strncmp(object, "LM", 2) == 0 &&
            (p = strchr(object, '`')) != NULL) {
                object += 2;    /* skip past initial "LM" prefix */
                lmid = strntoul(object, (size_t)(p - object), mdb.m_radix);
                object = p + 1; /* skip past link map specifier */
        }

        *lmidp = lmid;
        return (object);
}

static int
tlsbase(mdb_tgt_t *t, mdb_tgt_tid_t tid, Lmid_t lmid, const char *object,
    psaddr_t *basep)
{
        pt_data_t *pt = t->t_data;
        const rd_loadobj_t *loadobjp;
        td_thrhandle_t th;
        td_err_e err;

        if (object == MDB_TGT_OBJ_EVERY)
                return (set_errno(EINVAL));

        if (t->t_pshandle == NULL || Pstate(t->t_pshandle) == PS_IDLE)
                return (set_errno(EMDB_NOPROC));

        if (pt->p_tdb_ops == NULL)
                return (set_errno(EMDB_TDB));

        err = pt->p_tdb_ops->td_ta_map_id2thr(pt->p_ptl_hdl, tid, &th);
        if (err != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        /*
         * If this fails, rtld_db has failed to initialize properly.
         */
        if ((loadobjp = Plmid_to_loadobj(t->t_pshandle, lmid, object)) == NULL)
                return (set_errno(EMDB_NORTLD));

        /*
         * This will fail if the TLS block has not been allocated for the
         * object that contains the TLS symbol in question.
         */
        err = pt->p_tdb_ops->td_thr_tlsbase(&th, loadobjp->rl_tlsmodid, basep);
        if (err != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

typedef struct {
        mdb_tgt_t       *pl_tgt;
        const char      *pl_name;
        Lmid_t          pl_lmid;
        GElf_Sym        *pl_symp;
        mdb_syminfo_t   *pl_sip;
        mdb_tgt_tid_t   pl_tid;
        mdb_bool_t      pl_found;
} pt_lookup_t;

/*ARGSUSED*/
static int
pt_lookup_cb(void *data, const prmap_t *pmp, const char *object)
{
        pt_lookup_t *plp = data;
        struct ps_prochandle *P = plp->pl_tgt->t_pshandle;
        prsyminfo_t si;
        GElf_Sym sym;

        if (Pxlookup_by_name(P, plp->pl_lmid, object, plp->pl_name, &sym,
            &si) != 0)
                return (0);

        /*
         * If we encounter a match with SHN_UNDEF, keep looking for a
         * better match. Return the first match with SHN_UNDEF set if no
         * better match is found.
         */
        if (sym.st_shndx == SHN_UNDEF) {
                if (!plp->pl_found) {
                        plp->pl_found = TRUE;
                        *plp->pl_symp = sym;
                        plp->pl_sip->sym_table = si.prs_table;
                        plp->pl_sip->sym_id = si.prs_id;
                }

                return (0);
        }

        /*
         * Note that if the symbol's st_shndx is SHN_UNDEF we don't have the
         * TLS offset anyway, so adding in the tlsbase would be worthless.
         */
        if (GELF_ST_TYPE(sym.st_info) == STT_TLS &&
            plp->pl_tid != (mdb_tgt_tid_t)-1) {
                psaddr_t base;

                if (tlsbase(plp->pl_tgt, plp->pl_tid, plp->pl_lmid, object,
                    &base) != 0)
                        return (-1); /* errno is set for us */

                sym.st_value += base;
        }

        plp->pl_found = TRUE;
        *plp->pl_symp = sym;
        plp->pl_sip->sym_table = si.prs_table;
        plp->pl_sip->sym_id = si.prs_id;

        return (1);
}

/*
 * Lookup the symbol with a thread context so that we can adjust TLS symbols
 * to get the values as they would appear in the context of the given thread.
 */
static int
pt_lookup_by_name_thr(mdb_tgt_t *t, const char *object,
    const char *name, GElf_Sym *symp, mdb_syminfo_t *sip, mdb_tgt_tid_t tid)
{
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;
        Lmid_t lmid;
        uint_t i;
        const rd_loadobj_t *aout_lop;

        object = pt_resolve_lmid(object, &lmid);

        if (P != NULL) {
                pt_lookup_t pl;

                pl.pl_tgt = t;
                pl.pl_name = name;
                pl.pl_lmid = lmid;
                pl.pl_symp = symp;
                pl.pl_sip = sip;
                pl.pl_tid = tid;
                pl.pl_found = FALSE;

                if (object == MDB_TGT_OBJ_EVERY) {
                        if (Pobject_iter_resolved(P, pt_lookup_cb, &pl) == -1)
                                return (-1); /* errno is set for us */
                        if ((!pl.pl_found) &&
                            (Pobject_iter(P, pt_lookup_cb, &pl) == -1))
                                return (-1); /* errno is set for us */
                } else {
                        const prmap_t *pmp;

                        /*
                         * This can fail either due to an invalid lmid or
                         * an invalid object. To determine which is
                         * faulty, we test the lmid against known valid
                         * lmids and then see if using a wild-card lmid
                         * improves ths situation.
                         */
                        if ((pmp = Plmid_to_map(P, lmid, object)) == NULL) {
                                if (lmid != PR_LMID_EVERY &&
                                    lmid != LM_ID_BASE &&
                                    lmid != LM_ID_LDSO &&
                                    Plmid_to_map(P, PR_LMID_EVERY, object)
                                    != NULL)
                                        return (set_errno(EMDB_NOLMID));
                                else
                                        return (set_errno(EMDB_NOOBJ));
                        }

                        if (pt_lookup_cb(&pl, pmp, object) == -1)
                                return (-1); /* errno is set for us */
                }

                if (pl.pl_found)
                        return (0);
        }

        /*
         * If libproc doesn't have the symbols for rtld, we're cooked --
         * mdb doesn't have those symbols either.
         */
        if (object == MDB_TGT_OBJ_RTLD)
                return (set_errno(EMDB_NOSYM));

        if (object != MDB_TGT_OBJ_EXEC && object != MDB_TGT_OBJ_EVERY) {
                int status = mdb_gelf_symtab_lookup_by_file(pt->p_symtab,
                    object, name, symp, &sip->sym_id);

                if (status != 0) {
                        if (P != NULL &&
                            Plmid_to_map(P, PR_LMID_EVERY, object) != NULL)
                                return (set_errno(EMDB_NOSYM));
                        else
                                return (-1); /* errno set from lookup_by_file */
                }

                goto found;
        }

        if (mdb_gelf_symtab_lookup_by_name(pt->p_symtab, name, symp, &i) == 0) {
                sip->sym_table = MDB_TGT_SYMTAB;
                sip->sym_id = i;
                goto local_found;
        }

        if (mdb_gelf_symtab_lookup_by_name(pt->p_dynsym, name, symp, &i) == 0) {
                sip->sym_table = MDB_TGT_DYNSYM;
                sip->sym_id = i;
                goto local_found;
        }

        return (set_errno(EMDB_NOSYM));

local_found:
        if (pt->p_file != NULL &&
            pt->p_file->gf_ehdr.e_type == ET_DYN &&
            P != NULL &&
            (aout_lop = Pname_to_loadobj(P, PR_OBJ_EXEC)) != NULL)
                symp->st_value += aout_lop->rl_base;

found:
        /*
         * If the symbol has type TLS, libproc should have found the symbol
         * if it exists and has been allocated.
         */
        if (GELF_ST_TYPE(symp->st_info) == STT_TLS)
                return (set_errno(EMDB_TLS));

        return (0);
}

static int
pt_lookup_by_name(mdb_tgt_t *t, const char *object,
    const char *name, GElf_Sym *symp, mdb_syminfo_t *sip)
{
        return (pt_lookup_by_name_thr(t, object, name, symp, sip, PTL_TID(t)));
}

static int
pt_lookup_by_addr(mdb_tgt_t *t, uintptr_t addr, uint_t flags,
    char *buf, size_t nbytes, GElf_Sym *symp, mdb_syminfo_t *sip)
{
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;
        rd_plt_info_t rpi = { 0 };

        const char *pltsym;
        int rv, match, i;

        mdb_gelf_symtab_t *gsts[3];     /* mdb.m_prsym, .symtab, .dynsym */
        int gstc = 0;                   /* number of valid gsts[] entries */

        mdb_gelf_symtab_t *gst = NULL;  /* set if 'sym' is from a gst */
        const prmap_t *pmp = NULL;      /* set if 'sym' is from libproc */
        GElf_Sym sym;                   /* best symbol found so far if !exact */
        prsyminfo_t si;

        /*
         * Fill in our array of symbol table pointers with the private symbol
         * table, static symbol table, and dynamic symbol table if applicable.
         * These are done in order of precedence so that if we match and
         * MDB_TGT_SYM_EXACT is set, we need not look any further.
         */
        if (mdb.m_prsym != NULL)
                gsts[gstc++] = mdb.m_prsym;
        if (P == NULL && pt->p_symtab != NULL)
                gsts[gstc++] = pt->p_symtab;
        if (P == NULL && pt->p_dynsym != NULL)
                gsts[gstc++] = pt->p_dynsym;

        /*
         * Loop through our array attempting to match the address.  If we match
         * and we're in exact mode, we're done.  Otherwise save the symbol in
         * the local sym variable if it is closer than our previous match.
         * We explicitly watch for zero-valued symbols since DevPro insists
         * on storing __fsr_init_value's value as the symbol value instead
         * of storing it in a constant integer.
         */
        for (i = 0; i < gstc; i++) {
                if (mdb_gelf_symtab_lookup_by_addr(gsts[i], addr, flags, buf,
                    nbytes, symp, &sip->sym_id) != 0 || symp->st_value == 0)
                        continue;

                if (flags & MDB_TGT_SYM_EXACT) {
                        gst = gsts[i];
                        goto found;
                }

                if (gst == NULL || mdb_gelf_sym_closer(symp, &sym, addr)) {
                        gst = gsts[i];
                        sym = *symp;
                }
        }

        /*
         * If we have no libproc handle active, we're done: fail if gst is
         * NULL; otherwise copy out our best symbol and skip to the end.
         * We also skip to found if gst is the private symbol table: we
         * want this to always take precedence over PLT re-vectoring.
         */
        if (P == NULL || (gst != NULL && gst == mdb.m_prsym)) {
                if (gst == NULL)
                        return (set_errno(EMDB_NOSYMADDR));
                *symp = sym;
                goto found;
        }

        /*
         * Check to see if the address is in a PLT: if it is, use librtld_db to
         * attempt to resolve the PLT entry.  If the entry is bound, reset addr
         * to the bound address, add a special prefix to the caller's buf,
         * forget our previous guess, and then continue using the new addr.
         * If the entry is not bound, copy the corresponding symbol name into
         * buf and return a fake symbol for the given address.
         */
        if ((pltsym = Ppltdest(P, addr)) != NULL) {
                const rd_loadobj_t *rlp;
                rd_agent_t *rap;

                if ((rap = Prd_agent(P)) != NULL &&
                    (rlp = Paddr_to_loadobj(P, addr)) != NULL &&
                    rd_plt_resolution(rap, addr, Pstatus(P)->pr_lwp.pr_lwpid,
                    rlp->rl_plt_base, &rpi) == RD_OK &&
                    (rpi.pi_flags & RD_FLG_PI_PLTBOUND)) {
                        size_t n;
                        n = mdb_iob_snprintf(buf, nbytes, "PLT=");
                        addr = rpi.pi_baddr;
                        if (n > nbytes) {
                                buf += nbytes;
                                nbytes = 0;
                        } else {
                                buf += n;
                                nbytes -= n;
                        }
                        gst = NULL;
                } else {
                        (void) mdb_iob_snprintf(buf, nbytes, "PLT:%s", pltsym);
                        bzero(symp, sizeof (GElf_Sym));
                        symp->st_value = addr;
                        symp->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC);
                        return (0);
                }
        }

        /*
         * Ask libproc to convert the address to the closest symbol for us.
         * Once we get the closest symbol, we perform the EXACT match or
         * smart-mode or absolute distance check ourself:
         */
        if (PT_LIBPROC_RESOLVE(P)) {
                rv = Pxlookup_by_addr_resolved(P, addr, buf, nbytes,
                    symp, &si);
        } else {
                rv = Pxlookup_by_addr(P, addr, buf, nbytes,
                    symp, &si);
        }
        if ((rv == 0) && (symp->st_value != 0) &&
            (gst == NULL || mdb_gelf_sym_closer(symp, &sym, addr))) {

                if (flags & MDB_TGT_SYM_EXACT)
                        match = (addr == symp->st_value);
                else if (mdb.m_symdist == 0)
                        match = (addr >= symp->st_value &&
                            addr < symp->st_value + symp->st_size);
                else
                        match = (addr >= symp->st_value &&
                            addr < symp->st_value + mdb.m_symdist);

                if (match) {
                        pmp = Paddr_to_map(P, addr);
                        gst = NULL;
                        sip->sym_table = si.prs_table;
                        sip->sym_id = si.prs_id;
                        goto found;
                }
        }

        /*
         * If we get here, Plookup_by_addr has failed us.  If we have no
         * previous best symbol (gst == NULL), we've failed completely.
         * Otherwise we copy out that symbol and continue on to 'found'.
         */
        if (gst == NULL)
                return (set_errno(EMDB_NOSYMADDR));
        *symp = sym;
found:
        /*
         * Once we've found something, copy the final name into the caller's
         * buffer and prefix it with the mapping name if appropriate.
         */
        if (pmp != NULL && pmp != Pname_to_map(P, PR_OBJ_EXEC)) {
                const char *prefix = pmp->pr_mapname;
                Lmid_t lmid;

                if (PT_LIBPROC_RESOLVE(P)) {
                        if (Pobjname_resolved(P, addr, pt->p_objname,
                            MDB_TGT_MAPSZ))
                                prefix = pt->p_objname;
                } else {
                        if (Pobjname(P, addr, pt->p_objname, MDB_TGT_MAPSZ))
                                prefix = pt->p_objname;
                }

                if (buf != NULL && nbytes > 1) {
                        (void) strncpy(pt->p_symname, buf, MDB_TGT_SYM_NAMLEN);
                        pt->p_symname[MDB_TGT_SYM_NAMLEN - 1] = '\0';
                } else {
                        pt->p_symname[0] = '\0';
                }

                if (prefix == pt->p_objname && Plmid(P, addr, &lmid) == 0 && (
                    (lmid != LM_ID_BASE && lmid != LM_ID_LDSO) ||
                    (mdb.m_flags & MDB_FL_SHOWLMID))) {
                        (void) mdb_iob_snprintf(buf, nbytes, "LM%lr`%s`%s",
                            lmid, strbasename(prefix), pt->p_symname);
                } else {
                        (void) mdb_iob_snprintf(buf, nbytes, "%s`%s",
                            strbasename(prefix), pt->p_symname);
                }

        } else if (gst != NULL && buf != NULL && nbytes > 0) {
                (void) strncpy(buf, mdb_gelf_sym_name(gst, symp), nbytes);
                buf[nbytes - 1] = '\0';
        }

        return (0);
}


static int
pt_symbol_iter_cb(void *arg, const GElf_Sym *sym, const char *name,
    const prsyminfo_t *sip)
{
        pt_symarg_t *psp = arg;

        psp->psym_info.sym_id = sip->prs_id;

        return (psp->psym_func(psp->psym_private, sym, name, &psp->psym_info,
            psp->psym_obj));
}

static int
pt_objsym_iter(void *arg, const prmap_t *pmp, const char *object)
{
        Lmid_t lmid = PR_LMID_EVERY;
        pt_symarg_t *psp = arg;

        psp->psym_obj = object;

        (void) Plmid(psp->psym_targ->t_pshandle, pmp->pr_vaddr, &lmid);
        (void) Pxsymbol_iter(psp->psym_targ->t_pshandle, lmid, object,
            psp->psym_which, psp->psym_type, pt_symbol_iter_cb, arg);

        return (0);
}

static int
pt_symbol_filt(void *arg, const GElf_Sym *sym, const char *name, uint_t id)
{
        pt_symarg_t *psp = arg;

        if (mdb_tgt_sym_match(sym, psp->psym_type)) {
                psp->psym_info.sym_id = id;
                return (psp->psym_func(psp->psym_private, sym, name,
                    &psp->psym_info, psp->psym_obj));
        }

        return (0);
}

static int
pt_symbol_iter(mdb_tgt_t *t, const char *object, uint_t which,
    uint_t type, mdb_tgt_sym_f *func, void *private)
{
        pt_data_t *pt = t->t_data;
        mdb_gelf_symtab_t *gst;
        pt_symarg_t ps;
        Lmid_t lmid;

        object = pt_resolve_lmid(object, &lmid);

        ps.psym_targ = t;
        ps.psym_which = which;
        ps.psym_type = type;
        ps.psym_func = func;
        ps.psym_private = private;
        ps.psym_obj = object;

        if (t->t_pshandle != NULL) {
                if (object != MDB_TGT_OBJ_EVERY) {
                        if (Plmid_to_map(t->t_pshandle, lmid, object) == NULL)
                                return (set_errno(EMDB_NOOBJ));
                        (void) Pxsymbol_iter(t->t_pshandle, lmid, object,
                            which, type, pt_symbol_iter_cb, &ps);
                        return (0);
                } else if (Prd_agent(t->t_pshandle) != NULL) {
                        if (PT_LIBPROC_RESOLVE(t->t_pshandle)) {
                                (void) Pobject_iter_resolved(t->t_pshandle,
                                    pt_objsym_iter, &ps);
                        } else {
                                (void) Pobject_iter(t->t_pshandle,
                                    pt_objsym_iter, &ps);
                        }
                        return (0);
                }
        }

        if (lmid != LM_ID_BASE && lmid != PR_LMID_EVERY)
                return (set_errno(EMDB_NOLMID));

        if (object != MDB_TGT_OBJ_EXEC && object != MDB_TGT_OBJ_EVERY &&
            pt->p_fio != NULL &&
            strcmp(object, IOP_NAME(pt->p_fio)) != 0)
                return (set_errno(EMDB_NOOBJ));

        if (which == MDB_TGT_SYMTAB)
                gst = pt->p_symtab;
        else
                gst = pt->p_dynsym;

        if (gst != NULL) {
                ps.psym_info.sym_table = gst->gst_tabid;
                mdb_gelf_symtab_iter(gst, pt_symbol_filt, &ps);
        }

        return (0);
}

static const mdb_map_t *
pt_prmap_to_mdbmap(mdb_tgt_t *t, const prmap_t *prp, mdb_map_t *mp)
{
        struct ps_prochandle *P = t->t_pshandle;
        char *rv, name[MAXPATHLEN];
        Lmid_t lmid;

        if (PT_LIBPROC_RESOLVE(P)) {
                rv = Pobjname_resolved(P, prp->pr_vaddr, name, sizeof (name));
        } else {
                rv = Pobjname(P, prp->pr_vaddr, name, sizeof (name));
        }

        if (rv != NULL) {
                if (Plmid(P, prp->pr_vaddr, &lmid) == 0 && (
                    (lmid != LM_ID_BASE && lmid != LM_ID_LDSO) ||
                    (mdb.m_flags & MDB_FL_SHOWLMID))) {
                        (void) mdb_iob_snprintf(mp->map_name, MDB_TGT_MAPSZ,
                            "LM%lr`%s", lmid, name);
                } else {
                        (void) strncpy(mp->map_name, name, MDB_TGT_MAPSZ - 1);
                        mp->map_name[MDB_TGT_MAPSZ - 1] = '\0';
                }
        } else {
                (void) strncpy(mp->map_name, prp->pr_mapname,
                    MDB_TGT_MAPSZ - 1);
                mp->map_name[MDB_TGT_MAPSZ - 1] = '\0';
        }

        mp->map_base = prp->pr_vaddr;
        mp->map_size = prp->pr_size;
        mp->map_flags = 0;

        if (prp->pr_mflags & MA_READ)
                mp->map_flags |= MDB_TGT_MAP_R;
        if (prp->pr_mflags & MA_WRITE)
                mp->map_flags |= MDB_TGT_MAP_W;
        if (prp->pr_mflags & MA_EXEC)
                mp->map_flags |= MDB_TGT_MAP_X;

        if (prp->pr_mflags & MA_SHM)
                mp->map_flags |= MDB_TGT_MAP_SHMEM;
        if (prp->pr_mflags & MA_BREAK)
                mp->map_flags |= MDB_TGT_MAP_HEAP;
        if (prp->pr_mflags & MA_STACK)
                mp->map_flags |= MDB_TGT_MAP_STACK;
        if (prp->pr_mflags & MA_ANON)
                mp->map_flags |= MDB_TGT_MAP_ANON;

        return (mp);
}

/*ARGSUSED*/
static int
pt_map_apply(void *arg, const prmap_t *prp, const char *name)
{
        pt_maparg_t *pmp = arg;
        mdb_map_t map;

        return (pmp->pmap_func(pmp->pmap_private,
            pt_prmap_to_mdbmap(pmp->pmap_targ, prp, &map), map.map_name));
}

static int
pt_mapping_iter(mdb_tgt_t *t, mdb_tgt_map_f *func, void *private)
{
        if (t->t_pshandle != NULL) {
                pt_maparg_t pm;

                pm.pmap_targ = t;
                pm.pmap_func = func;
                pm.pmap_private = private;

                if (PT_LIBPROC_RESOLVE(t->t_pshandle)) {
                        (void) Pmapping_iter_resolved(t->t_pshandle,
                            pt_map_apply, &pm);
                } else {
                        (void) Pmapping_iter(t->t_pshandle,
                            pt_map_apply, &pm);
                }
                return (0);
        }

        return (set_errno(EMDB_NOPROC));
}

static int
pt_object_iter(mdb_tgt_t *t, mdb_tgt_map_f *func, void *private)
{
        pt_data_t *pt = t->t_data;

        /*
         * If we have a libproc handle, we can just call Pobject_iter to
         * iterate over its list of load object information.
         */
        if (t->t_pshandle != NULL) {
                pt_maparg_t pm;

                pm.pmap_targ = t;
                pm.pmap_func = func;
                pm.pmap_private = private;

                if (PT_LIBPROC_RESOLVE(t->t_pshandle)) {
                        (void) Pobject_iter_resolved(t->t_pshandle,
                            pt_map_apply, &pm);
                } else {
                        (void) Pobject_iter(t->t_pshandle,
                            pt_map_apply, &pm);
                }
                return (0);
        }

        /*
         * If we're examining an executable or other ELF file but we have no
         * libproc handle, fake up some information based on DT_NEEDED entries.
         */
        if (pt->p_dynsym != NULL && pt->p_file->gf_dyns != NULL &&
            pt->p_fio != NULL) {
                mdb_gelf_sect_t *gsp = pt->p_dynsym->gst_ssect;
                GElf_Dyn *dynp = pt->p_file->gf_dyns;
                mdb_map_t *mp = &pt->p_map;
                const char *s = IOP_NAME(pt->p_fio);
                size_t i;

                (void) strncpy(mp->map_name, s, MDB_TGT_MAPSZ);
                mp->map_name[MDB_TGT_MAPSZ - 1] = '\0';
                mp->map_flags = MDB_TGT_MAP_R | MDB_TGT_MAP_X;
                mp->map_base = NULL;
                mp->map_size = 0;

                if (func(private, mp, s) != 0)
                        return (0);

                for (i = 0; i < pt->p_file->gf_ndyns; i++, dynp++) {
                        if (dynp->d_tag == DT_NEEDED) {
                                s = (char *)gsp->gs_data + dynp->d_un.d_val;
                                (void) strncpy(mp->map_name, s, MDB_TGT_MAPSZ);
                                mp->map_name[MDB_TGT_MAPSZ - 1] = '\0';
                                if (func(private, mp, s) != 0)
                                        return (0);
                        }
                }

                return (0);
        }

        return (set_errno(EMDB_NOPROC));
}

static const mdb_map_t *
pt_addr_to_map(mdb_tgt_t *t, uintptr_t addr)
{
        pt_data_t *pt = t->t_data;
        const prmap_t *pmp;

        if (t->t_pshandle == NULL) {
                (void) set_errno(EMDB_NOPROC);
                return (NULL);
        }

        if ((pmp = Paddr_to_map(t->t_pshandle, addr)) == NULL) {
                (void) set_errno(EMDB_NOMAP);
                return (NULL);
        }

        return (pt_prmap_to_mdbmap(t, pmp, &pt->p_map));
}

static const mdb_map_t *
pt_name_to_map(mdb_tgt_t *t, const char *object)
{
        pt_data_t *pt = t->t_data;
        const prmap_t *pmp;
        Lmid_t lmid;

        if (t->t_pshandle == NULL) {
                (void) set_errno(EMDB_NOPROC);
                return (NULL);
        }

        object = pt_resolve_lmid(object, &lmid);

        if ((pmp = Plmid_to_map(t->t_pshandle, lmid, object)) == NULL) {
                (void) set_errno(EMDB_NOOBJ);
                return (NULL);
        }

        return (pt_prmap_to_mdbmap(t, pmp, &pt->p_map));
}

static ctf_file_t *
pt_addr_to_ctf(mdb_tgt_t *t, uintptr_t addr)
{
        ctf_file_t *ret;

        if (t->t_pshandle == NULL) {
                (void) set_errno(EMDB_NOPROC);
                return (NULL);
        }

        if ((ret = Paddr_to_ctf(t->t_pshandle, addr)) == NULL) {
                (void) set_errno(EMDB_NOOBJ);
                return (NULL);
        }

        return (ret);
}

static ctf_file_t *
pt_name_to_ctf(mdb_tgt_t *t, const char *name)
{
        ctf_file_t *ret;

        if (t->t_pshandle == NULL) {
                (void) set_errno(EMDB_NOPROC);
                return (NULL);
        }

        if ((ret = Pname_to_ctf(t->t_pshandle, name)) == NULL) {
                (void) set_errno(EMDB_NOOBJ);
                return (NULL);
        }

        return (ret);
}

static int
pt_status(mdb_tgt_t *t, mdb_tgt_status_t *tsp)
{
        const pstatus_t *psp;
        prgregset_t gregs;
        int state;

        bzero(tsp, sizeof (mdb_tgt_status_t));

        if (t->t_pshandle == NULL) {
                tsp->st_state = MDB_TGT_IDLE;
                return (0);
        }

        switch (state = Pstate(t->t_pshandle)) {
        case PS_RUN:
                tsp->st_state = MDB_TGT_RUNNING;
                break;

        case PS_STOP:
                tsp->st_state = MDB_TGT_STOPPED;
                psp = Pstatus(t->t_pshandle);

                tsp->st_tid = PTL_TID(t);
                if (PTL_GETREGS(t, tsp->st_tid, gregs) == 0)
                        tsp->st_pc = gregs[R_PC];

                if (psp->pr_flags & PR_ISTOP)
                        tsp->st_flags |= MDB_TGT_ISTOP;
                if (psp->pr_flags & PR_DSTOP)
                        tsp->st_flags |= MDB_TGT_DSTOP;

                break;

        case PS_LOST:
                tsp->st_state = MDB_TGT_LOST;
                break;
        case PS_UNDEAD:
                tsp->st_state = MDB_TGT_UNDEAD;
                break;
        case PS_DEAD:
                tsp->st_state = MDB_TGT_DEAD;
                break;
        case PS_IDLE:
                tsp->st_state = MDB_TGT_IDLE;
                break;
        default:
                fail("unknown libproc state (%d)\n", state);
        }

        if (t->t_flags & MDB_TGT_F_BUSY)
                tsp->st_flags |= MDB_TGT_BUSY;

        return (0);
}

static void
pt_dupfd(const char *file, int oflags, mode_t mode, int dfd)
{
        int fd;

        if ((fd = open(file, oflags, mode)) >= 0) {
                (void) fcntl(fd, F_DUP2FD, dfd);
                (void) close(fd);
        } else
                warn("failed to open %s as descriptor %d", file, dfd);
}

/*
 * The Pcreate_callback() function interposes on the default, empty libproc
 * definition.  It will be called following a fork of a new child process by
 * Pcreate() below, but before the exec of the new process image.  We use this
 * callback to optionally redirect stdin and stdout and reset the dispositions
 * of SIGPIPE and SIGQUIT from SIG_IGN back to SIG_DFL.
 */
/*ARGSUSED*/
void
Pcreate_callback(struct ps_prochandle *P)
{
        pt_data_t *pt = mdb.m_target->t_data;

        if (pt->p_stdin != NULL)
                pt_dupfd(pt->p_stdin, O_RDWR, 0, STDIN_FILENO);
        if (pt->p_stdout != NULL)
                pt_dupfd(pt->p_stdout, O_CREAT | O_WRONLY, 0666, STDOUT_FILENO);

        (void) mdb_signal_sethandler(SIGPIPE, SIG_DFL, NULL);
        (void) mdb_signal_sethandler(SIGQUIT, SIG_DFL, NULL);
}

static int
pt_run(mdb_tgt_t *t, int argc, const mdb_arg_t *argv)
{
        pt_data_t *pt = t->t_data;
        struct ps_prochandle *P;
        char execname[MAXPATHLEN];
        const char **pargv;
        int pargc = 0;
        int i, perr;
        char **penv;
        mdb_var_t *v;

        if (pt->p_aout_fio == NULL) {
                warn("run requires executable to be specified on "
                    "command-line\n");
                return (set_errno(EMDB_TGT));
        }

        pargv = mdb_alloc(sizeof (char *) * (argc + 2), UM_SLEEP);
        pargv[pargc++] = strbasename(IOP_NAME(pt->p_aout_fio));

        for (i = 0; i < argc; i++) {
                if (argv[i].a_type != MDB_TYPE_STRING) {
                        mdb_free(pargv, sizeof (char *) * (argc + 2));
                        return (set_errno(EINVAL));
                }
                if (argv[i].a_un.a_str[0] == '<')
                        pt->p_stdin = argv[i].a_un.a_str + 1;
                else if (argv[i].a_un.a_str[0] == '>')
                        pt->p_stdout = argv[i].a_un.a_str + 1;
                else
                        pargv[pargc++] = argv[i].a_un.a_str;
        }
        pargv[pargc] = NULL;

        /*
         * Since Pcreate() uses execvp() and "." may not be present in $PATH,
         * we must manually prepend "./" when the executable is a simple name.
         */
        if (strchr(IOP_NAME(pt->p_aout_fio), '/') == NULL) {
                (void) snprintf(execname, sizeof (execname), "./%s",
                    IOP_NAME(pt->p_aout_fio));
        } else {
                (void) snprintf(execname, sizeof (execname), "%s",
                    IOP_NAME(pt->p_aout_fio));
        }

        penv = mdb_alloc((mdb_nv_size(&pt->p_env)+ 1) * sizeof (char *),
            UM_SLEEP);
        for (mdb_nv_rewind(&pt->p_env), i = 0;
            (v = mdb_nv_advance(&pt->p_env)) != NULL; i++)
                penv[i] = mdb_nv_get_cookie(v);
        penv[i] = NULL;

        P = Pxcreate(execname, (char **)pargv, penv, &perr, NULL, 0);
        mdb_free(pargv, sizeof (char *) * (argc + 2));
        pt->p_stdin = pt->p_stdout = NULL;

        mdb_free(penv, i * sizeof (char *));

        if (P == NULL) {
                warn("failed to create process: %s\n", Pcreate_error(perr));
                return (set_errno(EMDB_TGT));
        }

        if (t->t_pshandle != NULL) {
                pt_pre_detach(t, TRUE);
                if (t->t_pshandle != pt->p_idlehandle)
                        Prelease(t->t_pshandle, pt->p_rflags);
        }

        (void) Punsetflags(P, PR_RLC);  /* make sure run-on-last-close is off */
        (void) Psetflags(P, PR_KLC);    /* kill on last close by debugger */
        pt->p_rflags = PRELEASE_KILL;   /* kill on debugger Prelease */
        t->t_pshandle = P;

        pt_post_attach(t);
        pt_activate_common(t);
        (void) mdb_tgt_status(t, &t->t_status);
        mdb.m_flags |= MDB_FL_VCREATE;

        return (0);
}

/*
 * Forward a signal to the victim process in order to force it to stop or die.
 * Refer to the comments above pt_setrun(), below, for more info.
 */
/*ARGSUSED*/
static void
pt_sigfwd(int sig, siginfo_t *sip, ucontext_t *ucp, mdb_tgt_t *t)
{
        struct ps_prochandle *P = t->t_pshandle;
        const lwpstatus_t *psp = &Pstatus(P)->pr_lwp;
        pid_t pid = Pstatus(P)->pr_pid;
        long ctl[2];

        if (getpgid(pid) != mdb.m_pgid) {
                mdb_dprintf(MDB_DBG_TGT, "fwd SIG#%d to %d\n", sig, (int)pid);
                (void) kill(pid, sig);
        }

        if (Pwait(P, 1) == 0 && (psp->pr_flags & PR_STOPPED) &&
            psp->pr_why == PR_JOBCONTROL && Pdstop(P) == 0) {
                /*
                 * If we're job control stopped and our DSTOP is pending, the
                 * victim will never see our signal, so undo the kill() and
                 * then send SIGCONT the victim to kick it out of the job
                 * control stop and force our DSTOP to take effect.
                 */
                if ((psp->pr_flags & PR_DSTOP) &&
                    prismember(&Pstatus(P)->pr_sigpend, sig)) {
                        ctl[0] = PCUNKILL;
                        ctl[1] = sig;
                        (void) write(Pctlfd(P), ctl, sizeof (ctl));
                }

                mdb_dprintf(MDB_DBG_TGT, "fwd SIGCONT to %d\n", (int)pid);
                (void) kill(pid, SIGCONT);
        }
}

/*
 * Common code for step and continue: if no victim process has been created,
 * call pt_run() to create one.  Then set the victim running, clearing any
 * pending fault.  One special case is that if the victim was previously
 * stopped on reception of SIGINT, we know that SIGINT was traced and the user
 * requested the victim to stop, so clear this signal before continuing.
 * For all other traced signals, the signal will be delivered on continue.
 *
 * Once the victim process is running, we wait for it to stop on an event of
 * interest.  Although libproc provides the basic primitive to wait for the
 * victim, we must be careful in our handling of signals.  We want to allow the
 * user to issue a SIGINT or SIGQUIT using the designated terminal control
 * character (typically ^C and ^\), and have these signals stop the target and
 * return control to the debugger if the signals are traced.  There are three
 * cases to be considered in our implementation:
 *
 * (1) If the debugger and victim are in the same process group, both receive
 * the signal from the terminal driver.  The debugger returns from Pwait() with
 * errno = EINTR, so we want to loop back and continue waiting until the victim
 * stops on receipt of its SIGINT or SIGQUIT.
 *
 * (2) If the debugger and victim are in different process groups, and the
 * victim is a member of the foreground process group, it will receive the
 * signal from the terminal driver and the debugger will not.  As such, we
 * will remain blocked in Pwait() until the victim stops on its signal.
 *
 * (3) If the debugger and victim are in different process groups, and the
 * debugger is a member of the foreground process group, it will receive the
 * signal from the terminal driver, and the victim will not.  The debugger
 * returns from Pwait() with errno = EINTR, so we need to forward the signal
 * to the victim process directly and then Pwait() again for it to stop.
 *
 * We can observe that all three cases are handled by simply calling Pwait()
 * repeatedly if it fails with EINTR, and forwarding SIGINT and SIGQUIT to
 * the victim if it is in a different process group, using pt_sigfwd() above.
 *
 * An additional complication is that the process may not be able to field
 * the signal if it is currently stopped by job control.  In this case, we
 * also DSTOP the process, and then send it a SIGCONT to wake it up from
 * job control and force it to re-enter stop() under the control of /proc.
 *
 * Finally, we would like to allow the user to suspend the process using the
 * terminal suspend character (typically ^Z) if both are in the same session.
 * We again employ pt_sigfwd() to forward SIGTSTP to the victim, wait for it to
 * stop from job control, and then capture it using /proc.  Once the process
 * has stopped, normal SIGTSTP processing is restored and the user can issue
 * another ^Z in order to suspend the debugger and return to the parent shell.
 */
static int
pt_setrun(mdb_tgt_t *t, mdb_tgt_status_t *tsp, int flags)
{
        struct ps_prochandle *P = t->t_pshandle;
        pt_data_t *pt = t->t_data;
        pid_t old_pgid = -1;

        mdb_signal_f *intf, *quitf, *tstpf;
        const lwpstatus_t *psp;
        void *intd, *quitd, *tstpd;

        int sig = pt->p_signal;
        int error = 0;
        int pgid = -1;

        pt->p_signal = 0; /* clear pending signal */

        if (P == NULL && pt_run(t, 0, NULL) == -1)
                return (-1); /* errno is set for us */

        P = t->t_pshandle;
        psp = &Pstatus(P)->pr_lwp;

        if (sig == 0 && psp->pr_why == PR_SIGNALLED && psp->pr_what == SIGINT)
                flags |= PRCSIG; /* clear pending SIGINT */
        else
                flags |= PRCFAULT; /* clear any pending fault (e.g. BPT) */

        intf = mdb_signal_gethandler(SIGINT, &intd);
        quitf = mdb_signal_gethandler(SIGQUIT, &quitd);
        tstpf = mdb_signal_gethandler(SIGTSTP, &tstpd);

        (void) mdb_signal_sethandler(SIGINT, (mdb_signal_f *)pt_sigfwd, t);
        (void) mdb_signal_sethandler(SIGQUIT, (mdb_signal_f *)pt_sigfwd, t);
        (void) mdb_signal_sethandler(SIGTSTP, (mdb_signal_f *)pt_sigfwd, t);

        if (sig != 0 && Pstate(P) == PS_RUN &&
            kill(Pstatus(P)->pr_pid, sig) == -1) {
                error = errno;
                goto out;
        }

        /*
         * If we attached to a job stopped background process in the same
         * session, make its pgid the foreground process group before running
         * it.  Ignore SIGTTOU while doing this to avoid being suspended.
         */
        if (mdb.m_flags & MDB_FL_JOBCTL) {
                (void) mdb_signal_sethandler(SIGTTOU, SIG_IGN, NULL);
                (void) IOP_CTL(mdb.m_term, TIOCGPGRP, &old_pgid);
                (void) IOP_CTL(mdb.m_term, TIOCSPGRP,
                    (void *)&Pstatus(P)->pr_pgid);
                (void) mdb_signal_sethandler(SIGTTOU, SIG_DFL, NULL);
        }

        if (Pstate(P) != PS_RUN && Psetrun(P, sig, flags) == -1) {
                error = errno;
                goto out;
        }

        /*
         * If the process is stopped on job control, resume its process group
         * by sending it a SIGCONT if we are in the same session.  Otherwise
         * we have no choice but to wait for someone else to foreground it.
         */
        if (psp->pr_why == PR_JOBCONTROL) {
                if (mdb.m_flags & MDB_FL_JOBCTL)
                        (void) kill(-Pstatus(P)->pr_pgid, SIGCONT);
                else if (mdb.m_term != NULL)
                        warn("process is still suspended by job control ...\n");
        }

        /*
         * Wait for the process to stop.  As described above, we loop around if
         * we are interrupted (EINTR).  If we lose control, attempt to re-open
         * the process, or call pt_exec() if that fails to handle a re-exec.
         * If the process dies (ENOENT) or Pwait() fails, break out of the loop.
         */
        while (Pwait(P, 0) == -1) {
                if (errno != EINTR) {
                        if (Pstate(P) == PS_LOST) {
                                if (Preopen(P) == 0)
                                        continue; /* Pwait() again */
                                else
                                        pt_exec(t, 0, NULL);
                        } else if (errno != ENOENT)
                                warn("failed to wait for event");
                        break;
                }
        }

        /*
         * If we changed the foreground process group, restore the old pgid
         * while ignoring SIGTTOU so we are not accidentally suspended.
         */
        if (old_pgid != -1) {
                (void) mdb_signal_sethandler(SIGTTOU, SIG_IGN, NULL);
                (void) IOP_CTL(mdb.m_term, TIOCSPGRP, &pgid);
                (void) mdb_signal_sethandler(SIGTTOU, SIG_DFL, NULL);
        }

        /*
         * If we're now stopped on exit from a successful exec, release any
         * vfork parents and clean out their address space before returning
         * to tgt_continue() and perturbing the list of armed event specs.
         * If we're stopped for any other reason, just update the mappings.
         */
        switch (Pstate(P)) {
        case PS_STOP:
                if (psp->pr_why == PR_SYSEXIT && psp->pr_errno == 0 &&
                    psp->pr_what == SYS_execve)
                        pt_release_parents(t);
                else
                        Pupdate_maps(P);
                break;

        case PS_UNDEAD:
        case PS_LOST:
                pt_release_parents(t);
                break;
        }

out:
        (void) mdb_signal_sethandler(SIGINT, intf, intd);
        (void) mdb_signal_sethandler(SIGQUIT, quitf, quitd);
        (void) mdb_signal_sethandler(SIGTSTP, tstpf, tstpd);
        (void) pt_status(t, tsp);

        return (error ? set_errno(error) : 0);
}

static int
pt_step(mdb_tgt_t *t, mdb_tgt_status_t *tsp)
{
        return (pt_setrun(t, tsp, PRSTEP));
}

static int
pt_continue(mdb_tgt_t *t, mdb_tgt_status_t *tsp)
{
        return (pt_setrun(t, tsp, 0));
}

static int
pt_signal(mdb_tgt_t *t, int sig)
{
        pt_data_t *pt = t->t_data;

        if (sig > 0 && sig <= pt->p_maxsig) {
                pt->p_signal = sig; /* pending until next pt_setrun */
                return (0);
        }

        return (set_errno(EMDB_BADSIGNUM));
}

static int
pt_sysenter_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        struct ps_prochandle *P = t->t_pshandle;

        if (P != NULL && Pstate(P) < PS_LOST) {
                sep->se_data = args; /* data is raw system call number */
                return (Psysentry(P, (intptr_t)args, TRUE) < 0 ? -1 : 0);
        }

        return (set_errno(EMDB_NOPROC));
}

static void
pt_sysenter_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        (void) Psysentry(t->t_pshandle, (intptr_t)sep->se_data, FALSE);
}

/*ARGSUSED*/
static char *
pt_sysenter_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        char name[32];
        int sysnum;

        if (vep != NULL)
                sysnum = (intptr_t)vep->ve_args;
        else
                sysnum = (intptr_t)sep->se_data;

        (void) proc_sysname(sysnum, name, sizeof (name));
        (void) mdb_iob_snprintf(buf, nbytes, "stop on entry to %s", name);

        return (buf);
}

/*ARGSUSED*/
static int
pt_sysenter_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        int sysnum = (intptr_t)sep->se_data;

        return (psp->pr_why == PR_SYSENTRY && psp->pr_what == sysnum);
}

static const mdb_se_ops_t proc_sysenter_ops = {
        pt_sysenter_ctor,       /* se_ctor */
        pt_sysenter_dtor,       /* se_dtor */
        pt_sysenter_info,       /* se_info */
        no_se_secmp,            /* se_secmp */
        no_se_vecmp,            /* se_vecmp */
        no_se_arm,              /* se_arm */
        no_se_disarm,           /* se_disarm */
        no_se_cont,             /* se_cont */
        pt_sysenter_match       /* se_match */
};

static int
pt_sysexit_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        struct ps_prochandle *P = t->t_pshandle;

        if (P != NULL && Pstate(P) < PS_LOST) {
                sep->se_data = args; /* data is raw system call number */
                return (Psysexit(P, (intptr_t)args, TRUE) < 0 ? -1 : 0);
        }

        return (set_errno(EMDB_NOPROC));
}

static void
pt_sysexit_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        (void) Psysexit(t->t_pshandle, (intptr_t)sep->se_data, FALSE);
}

/*ARGSUSED*/
static char *
pt_sysexit_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        char name[32];
        int sysnum;

        if (vep != NULL)
                sysnum = (intptr_t)vep->ve_args;
        else
                sysnum = (intptr_t)sep->se_data;

        (void) proc_sysname(sysnum, name, sizeof (name));
        (void) mdb_iob_snprintf(buf, nbytes, "stop on exit from %s", name);

        return (buf);
}

/*ARGSUSED*/
static int
pt_sysexit_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        int sysnum = (intptr_t)sep->se_data;

        return (psp->pr_why == PR_SYSEXIT && psp->pr_what == sysnum);
}

static const mdb_se_ops_t proc_sysexit_ops = {
        pt_sysexit_ctor,        /* se_ctor */
        pt_sysexit_dtor,        /* se_dtor */
        pt_sysexit_info,        /* se_info */
        no_se_secmp,            /* se_secmp */
        no_se_vecmp,            /* se_vecmp */
        no_se_arm,              /* se_arm */
        no_se_disarm,           /* se_disarm */
        no_se_cont,             /* se_cont */
        pt_sysexit_match        /* se_match */
};

static int
pt_signal_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        struct ps_prochandle *P = t->t_pshandle;

        if (P != NULL && Pstate(P) < PS_LOST) {
                sep->se_data = args; /* data is raw signal number */
                return (Psignal(P, (intptr_t)args, TRUE) < 0 ? -1 : 0);
        }

        return (set_errno(EMDB_NOPROC));
}

static void
pt_signal_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        (void) Psignal(t->t_pshandle, (intptr_t)sep->se_data, FALSE);
}

/*ARGSUSED*/
static char *
pt_signal_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        char name[SIG2STR_MAX];
        int signum;

        if (vep != NULL)
                signum = (intptr_t)vep->ve_args;
        else
                signum = (intptr_t)sep->se_data;

        (void) proc_signame(signum, name, sizeof (name));
        (void) mdb_iob_snprintf(buf, nbytes, "stop on %s", name);

        return (buf);
}

/*ARGSUSED*/
static int
pt_signal_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        int signum = (intptr_t)sep->se_data;

        return (psp->pr_why == PR_SIGNALLED && psp->pr_what == signum);
}

static const mdb_se_ops_t proc_signal_ops = {
        pt_signal_ctor,         /* se_ctor */
        pt_signal_dtor,         /* se_dtor */
        pt_signal_info,         /* se_info */
        no_se_secmp,            /* se_secmp */
        no_se_vecmp,            /* se_vecmp */
        no_se_arm,              /* se_arm */
        no_se_disarm,           /* se_disarm */
        no_se_cont,             /* se_cont */
        pt_signal_match         /* se_match */
};

static int
pt_fault_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        struct ps_prochandle *P = t->t_pshandle;

        if (P != NULL && Pstate(P) < PS_LOST) {
                sep->se_data = args; /* data is raw fault number */
                return (Pfault(P, (intptr_t)args, TRUE) < 0 ? -1 : 0);
        }

        return (set_errno(EMDB_NOPROC));
}

static void
pt_fault_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        int fault = (intptr_t)sep->se_data;

        if (fault != FLTBPT && fault != FLTTRACE && fault != FLTWATCH)
                (void) Pfault(t->t_pshandle, fault, FALSE);
}

/*ARGSUSED*/
static char *
pt_fault_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        char name[32];
        int fltnum;

        if (vep != NULL)
                fltnum = (intptr_t)vep->ve_args;
        else
                fltnum = (intptr_t)sep->se_data;

        (void) proc_fltname(fltnum, name, sizeof (name));
        (void) mdb_iob_snprintf(buf, nbytes, "stop on %s", name);

        return (buf);
}

/*ARGSUSED*/
static int
pt_fault_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        int fltnum = (intptr_t)sep->se_data;

        return (psp->pr_why == PR_FAULTED && psp->pr_what == fltnum);
}

static const mdb_se_ops_t proc_fault_ops = {
        pt_fault_ctor,          /* se_ctor */
        pt_fault_dtor,          /* se_dtor */
        pt_fault_info,          /* se_info */
        no_se_secmp,            /* se_secmp */
        no_se_vecmp,            /* se_vecmp */
        no_se_arm,              /* se_arm */
        no_se_disarm,           /* se_disarm */
        no_se_cont,             /* se_cont */
        pt_fault_match          /* se_match */
};

/*
 * Callback for pt_ignore() dcmd above: for each VID, determine if it
 * corresponds to a vespec that traces the specified signal, and delete it.
 */
/*ARGSUSED*/
static int
pt_ignore_sig(mdb_tgt_t *t, void *sig, int vid, void *data)
{
        mdb_vespec_t *vep = mdb_tgt_vespec_lookup(t, vid);

        if (vep->ve_se->se_ops == &proc_signal_ops && vep->ve_args == sig)
                (void) mdb_tgt_vespec_delete(t, vid);

        return (0);
}

static int
pt_brkpt_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        pt_data_t *pt = t->t_data;
        pt_bparg_t *pta = args;
        pt_brkpt_t *ptb;
        GElf_Sym s;

        if (t->t_pshandle == NULL || Pstate(t->t_pshandle) >= PS_LOST)
                return (set_errno(EMDB_NOPROC));

        if (pta->pta_symbol != NULL) {
                if (!pt->p_rtld_finished &&
                    strchr(pta->pta_symbol, '`') == NULL)
                        return (set_errno(EMDB_NOSYM));
                if (mdb_tgt_lookup_by_scope(t, pta->pta_symbol, &s,
                    NULL) == -1) {
                        if (errno != EMDB_NOOBJ && !(errno == EMDB_NOSYM &&
                            (!(mdb.m_flags & MDB_FL_BPTNOSYMSTOP) ||
                            !pt->p_rtld_finished))) {
                                warn("breakpoint %s activation failed",
                                    pta->pta_symbol);
                        }
                        return (-1); /* errno is set for us */
                }

                pta->pta_addr = (uintptr_t)s.st_value;
        }

#ifdef __sparc
        if (pta->pta_addr & 3)
                return (set_errno(EMDB_BPALIGN));
#endif

        if (Paddr_to_map(t->t_pshandle, pta->pta_addr) == NULL)
                return (set_errno(EMDB_NOMAP));

        ptb = mdb_alloc(sizeof (pt_brkpt_t), UM_SLEEP);
        ptb->ptb_addr = pta->pta_addr;
        ptb->ptb_instr = NULL;
        sep->se_data = ptb;

        return (0);
}

/*ARGSUSED*/
static void
pt_brkpt_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        mdb_free(sep->se_data, sizeof (pt_brkpt_t));
}

/*ARGSUSED*/
static char *
pt_brkpt_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        uintptr_t addr = NULL;

        if (vep != NULL) {
                pt_bparg_t *pta = vep->ve_args;

                if (pta->pta_symbol != NULL) {
                        (void) mdb_iob_snprintf(buf, nbytes, "stop at %s",
                            pta->pta_symbol);
                } else {
                        (void) mdb_iob_snprintf(buf, nbytes, "stop at %a",
                            pta->pta_addr);
                        addr = pta->pta_addr;
                }

        } else {
                addr = ((pt_brkpt_t *)sep->se_data)->ptb_addr;
                (void) mdb_iob_snprintf(buf, nbytes, "stop at %a", addr);
        }

        sp->spec_base = addr;
        sp->spec_size = sizeof (instr_t);

        return (buf);
}

static int
pt_brkpt_secmp(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        pt_brkpt_t *ptb = sep->se_data;
        pt_bparg_t *pta = args;
        GElf_Sym sym;

        if (pta->pta_symbol != NULL) {
                return (mdb_tgt_lookup_by_scope(t, pta->pta_symbol,
                    &sym, NULL) == 0 && sym.st_value == ptb->ptb_addr);
        }

        return (pta->pta_addr == ptb->ptb_addr);
}

/*ARGSUSED*/
static int
pt_brkpt_vecmp(mdb_tgt_t *t, mdb_vespec_t *vep, void *args)
{
        pt_bparg_t *pta1 = vep->ve_args;
        pt_bparg_t *pta2 = args;

        if (pta1->pta_symbol != NULL && pta2->pta_symbol != NULL)
                return (strcmp(pta1->pta_symbol, pta2->pta_symbol) == 0);

        if (pta1->pta_symbol == NULL && pta2->pta_symbol == NULL)
                return (pta1->pta_addr == pta2->pta_addr);

        return (0); /* fail if one is symbolic, other is an explicit address */
}

static int
pt_brkpt_arm(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        pt_brkpt_t *ptb = sep->se_data;
        return (Psetbkpt(t->t_pshandle, ptb->ptb_addr, &ptb->ptb_instr));
}

/*
 * In order to disarm a breakpoint, we replace the trap instruction at ptb_addr
 * with the saved instruction.  However, if we have stopped after a successful
 * exec(2), we do not want to restore ptb_instr because the address space has
 * now been replaced with the text of a different executable, and so restoring
 * the saved instruction would be incorrect.  The exec itself has effectively
 * removed all breakpoint trap instructions for us, so we can just return.
 */
static int
pt_brkpt_disarm(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        pt_brkpt_t *ptb = sep->se_data;

        if (psp->pr_why == PR_SYSEXIT && psp->pr_errno == 0 &&
            psp->pr_what == SYS_execve)
                return (0); /* do not restore saved instruction */

        return (Pdelbkpt(t->t_pshandle, ptb->ptb_addr, ptb->ptb_instr));
}

/*
 * Determine whether the specified sespec is an armed watchpoint that overlaps
 * with the given breakpoint and has the given flags set.  We use this to find
 * conflicts with breakpoints, below.
 */
static int
pt_wp_overlap(mdb_sespec_t *sep, pt_brkpt_t *ptb, int flags)
{
        const prwatch_t *wp = sep->se_data;

        return (sep->se_state == MDB_TGT_SPEC_ARMED &&
            sep->se_ops == &proc_wapt_ops && (wp->pr_wflags & flags) &&
            ptb->ptb_addr - wp->pr_vaddr < wp->pr_size);
}

/*
 * We step over breakpoints using Pxecbkpt() in libproc.  If a conflicting
 * watchpoint is present, we must temporarily remove it before stepping over
 * the breakpoint so we do not immediately re-trigger the watchpoint.  We know
 * the watchpoint has already triggered on our trap instruction as part of
 * fetching it.  Before we return, we must re-install any disabled watchpoints.
 */
static int
pt_brkpt_cont(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        pt_brkpt_t *ptb = sep->se_data;
        int status = -1;
        int error;
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;

        /*
         * If the PC no longer matches our original address, then the user has
         * changed it while we have been stopped. In this case, it no longer
         * makes any sense to continue over this breakpoint.  We return as if we
         * continued normally.
         */
        if ((uintptr_t)psp->pr_info.si_addr != psp->pr_reg[R_PC])
                return (pt_status(t, tsp));

        for (sep = mdb_list_next(&t->t_active); sep; sep = mdb_list_next(sep)) {
                if (pt_wp_overlap(sep, ptb, WA_EXEC))
                        (void) Pdelwapt(t->t_pshandle, sep->se_data);
        }

        if (Pxecbkpt(t->t_pshandle, ptb->ptb_instr) == 0 &&
            Pdelbkpt(t->t_pshandle, ptb->ptb_addr, ptb->ptb_instr) == 0)
                status = pt_status(t, tsp);

        error = errno; /* save errno from Pxecbkpt, Pdelbkpt, or pt_status */

        for (sep = mdb_list_next(&t->t_active); sep; sep = mdb_list_next(sep)) {
                if (pt_wp_overlap(sep, ptb, WA_EXEC) &&
                    Psetwapt(t->t_pshandle, sep->se_data) == -1) {
                        sep->se_state = MDB_TGT_SPEC_ERROR;
                        sep->se_errno = errno;
                }
        }

        (void) set_errno(error);
        return (status);
}

/*ARGSUSED*/
static int
pt_brkpt_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        pt_brkpt_t *ptb = sep->se_data;

        return (psp->pr_why == PR_FAULTED && psp->pr_what == FLTBPT &&
            psp->pr_reg[R_PC] == ptb->ptb_addr);
}

static const mdb_se_ops_t proc_brkpt_ops = {
        pt_brkpt_ctor,          /* se_ctor */
        pt_brkpt_dtor,          /* se_dtor */
        pt_brkpt_info,          /* se_info */
        pt_brkpt_secmp,         /* se_secmp */
        pt_brkpt_vecmp,         /* se_vecmp */
        pt_brkpt_arm,           /* se_arm */
        pt_brkpt_disarm,        /* se_disarm */
        pt_brkpt_cont,          /* se_cont */
        pt_brkpt_match          /* se_match */
};

static int
pt_wapt_ctor(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        if (t->t_pshandle == NULL || Pstate(t->t_pshandle) >= PS_LOST)
                return (set_errno(EMDB_NOPROC));

        sep->se_data = mdb_alloc(sizeof (prwatch_t), UM_SLEEP);
        bcopy(args, sep->se_data, sizeof (prwatch_t));
        return (0);
}

/*ARGSUSED*/
static void
pt_wapt_dtor(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        mdb_free(sep->se_data, sizeof (prwatch_t));
}

/*ARGSUSED*/
static char *
pt_wapt_info(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_vespec_t *vep,
    mdb_tgt_spec_desc_t *sp, char *buf, size_t nbytes)
{
        prwatch_t *wp = vep != NULL ? vep->ve_args : sep->se_data;
        char desc[24];

        ASSERT(wp->pr_wflags != 0);
        desc[0] = '\0';

        switch (wp->pr_wflags) {
        case WA_READ:
                (void) strcat(desc, "/read");
                break;
        case WA_WRITE:
                (void) strcat(desc, "/write");
                break;
        case WA_EXEC:
                (void) strcat(desc, "/exec");
                break;
        default:
                if (wp->pr_wflags & WA_READ)
                        (void) strcat(desc, "/r");
                if (wp->pr_wflags & WA_WRITE)
                        (void) strcat(desc, "/w");
                if (wp->pr_wflags & WA_EXEC)
                        (void) strcat(desc, "/x");
        }

        (void) mdb_iob_snprintf(buf, nbytes, "stop on %s of [%la, %la)",
            desc + 1, wp->pr_vaddr, wp->pr_vaddr + wp->pr_size);

        sp->spec_base = wp->pr_vaddr;
        sp->spec_size = wp->pr_size;

        return (buf);
}

/*ARGSUSED*/
static int
pt_wapt_secmp(mdb_tgt_t *t, mdb_sespec_t *sep, void *args)
{
        prwatch_t *wp1 = sep->se_data;
        prwatch_t *wp2 = args;

        return (wp1->pr_vaddr == wp2->pr_vaddr &&
            wp1->pr_size == wp2->pr_size && wp1->pr_wflags == wp2->pr_wflags);
}

/*ARGSUSED*/
static int
pt_wapt_vecmp(mdb_tgt_t *t, mdb_vespec_t *vep, void *args)
{
        prwatch_t *wp1 = vep->ve_args;
        prwatch_t *wp2 = args;

        return (wp1->pr_vaddr == wp2->pr_vaddr &&
            wp1->pr_size == wp2->pr_size && wp1->pr_wflags == wp2->pr_wflags);
}

static int
pt_wapt_arm(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        return (Psetwapt(t->t_pshandle, sep->se_data));
}

static int
pt_wapt_disarm(mdb_tgt_t *t, mdb_sespec_t *sep)
{
        return (Pdelwapt(t->t_pshandle, sep->se_data));
}

/*
 * Determine whether the specified sespec is an armed breakpoint at the
 * given %pc.  We use this to find conflicts with watchpoints below.
 */
static int
pt_bp_overlap(mdb_sespec_t *sep, uintptr_t pc)
{
        pt_brkpt_t *ptb = sep->se_data;

        return (sep->se_state == MDB_TGT_SPEC_ARMED &&
            sep->se_ops == &proc_brkpt_ops && ptb->ptb_addr == pc);
}

/*
 * We step over watchpoints using Pxecwapt() in libproc.  If a conflicting
 * breakpoint is present, we must temporarily disarm it before stepping
 * over the watchpoint so we do not immediately re-trigger the breakpoint.
 * This is similar to the case handled in pt_brkpt_cont(), above.
 */
static int
pt_wapt_cont(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        mdb_sespec_t *bep = NULL;
        int status = -1;
        int error;

        /*
         * If the PC no longer matches our original address, then the user has
         * changed it while we have been stopped. In this case, it no longer
         * makes any sense to continue over this instruction.  We return as if
         * we continued normally.
         */
        if ((uintptr_t)psp->pr_info.si_pc != psp->pr_reg[R_PC])
                return (pt_status(t, tsp));

        if (psp->pr_info.si_code != TRAP_XWATCH) {
                for (bep = mdb_list_next(&t->t_active); bep != NULL;
                    bep = mdb_list_next(bep)) {
                        if (pt_bp_overlap(bep, psp->pr_reg[R_PC])) {
                                (void) bep->se_ops->se_disarm(t, bep);
                                bep->se_state = MDB_TGT_SPEC_ACTIVE;
                                break;
                        }
                }
        }

        if (Pxecwapt(t->t_pshandle, sep->se_data) == 0)
                status = pt_status(t, tsp);

        error = errno; /* save errno from Pxecwapt or pt_status */

        if (bep != NULL)
                mdb_tgt_sespec_arm_one(t, bep);

        (void) set_errno(error);
        return (status);
}

/*ARGSUSED*/
static int
pt_wapt_match(mdb_tgt_t *t, mdb_sespec_t *sep, mdb_tgt_status_t *tsp)
{
        const lwpstatus_t *psp = &Pstatus(t->t_pshandle)->pr_lwp;
        prwatch_t *wp = sep->se_data;

        return (psp->pr_why == PR_FAULTED && psp->pr_what == FLTWATCH &&
            (uintptr_t)psp->pr_info.si_addr - wp->pr_vaddr < wp->pr_size);
}

static const mdb_se_ops_t proc_wapt_ops = {
        pt_wapt_ctor,           /* se_ctor */
        pt_wapt_dtor,           /* se_dtor */
        pt_wapt_info,           /* se_info */
        pt_wapt_secmp,          /* se_secmp */
        pt_wapt_vecmp,          /* se_vecmp */
        pt_wapt_arm,            /* se_arm */
        pt_wapt_disarm,         /* se_disarm */
        pt_wapt_cont,           /* se_cont */
        pt_wapt_match           /* se_match */
};

static void
pt_bparg_dtor(mdb_vespec_t *vep)
{
        pt_bparg_t *pta = vep->ve_args;

        if (pta->pta_symbol != NULL)
                strfree(pta->pta_symbol);

        mdb_free(pta, sizeof (pt_bparg_t));
}

static int
pt_add_vbrkpt(mdb_tgt_t *t, uintptr_t addr,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        pt_bparg_t *pta = mdb_alloc(sizeof (pt_bparg_t), UM_SLEEP);

        pta->pta_symbol = NULL;
        pta->pta_addr = addr;

        return (mdb_tgt_vespec_insert(t, &proc_brkpt_ops, spec_flags,
            func, data, pta, pt_bparg_dtor));
}

static int
pt_add_sbrkpt(mdb_tgt_t *t, const char *sym,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        pt_bparg_t *pta;

        if (sym[0] == '`') {
                (void) set_errno(EMDB_NOOBJ);
                return (0);
        }

        if (sym[strlen(sym) - 1] == '`') {
                (void) set_errno(EMDB_NOSYM);
                return (0);
        }

        pta = mdb_alloc(sizeof (pt_bparg_t), UM_SLEEP);
        pta->pta_symbol = strdup(sym);
        pta->pta_addr = NULL;

        return (mdb_tgt_vespec_insert(t, &proc_brkpt_ops, spec_flags,
            func, data, pta, pt_bparg_dtor));
}

static int
pt_wparg_overlap(const prwatch_t *wp1, const prwatch_t *wp2)
{
        if (wp2->pr_vaddr + wp2->pr_size <= wp1->pr_vaddr)
                return (0); /* no range overlap */

        if (wp1->pr_vaddr + wp1->pr_size <= wp2->pr_vaddr)
                return (0); /* no range overlap */

        return (wp1->pr_vaddr != wp2->pr_vaddr ||
            wp1->pr_size != wp2->pr_size || wp1->pr_wflags != wp2->pr_wflags);
}

static void
pt_wparg_dtor(mdb_vespec_t *vep)
{
        mdb_free(vep->ve_args, sizeof (prwatch_t));
}

static int
pt_add_vwapt(mdb_tgt_t *t, uintptr_t addr, size_t len, uint_t wflags,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        prwatch_t *wp = mdb_alloc(sizeof (prwatch_t), UM_SLEEP);
        mdb_sespec_t *sep;

        wp->pr_vaddr = addr;
        wp->pr_size = len;
        wp->pr_wflags = 0;

        if (wflags & MDB_TGT_WA_R)
                wp->pr_wflags |= WA_READ;
        if (wflags & MDB_TGT_WA_W)
                wp->pr_wflags |= WA_WRITE;
        if (wflags & MDB_TGT_WA_X)
                wp->pr_wflags |= WA_EXEC;

        for (sep = mdb_list_next(&t->t_active); sep; sep = mdb_list_next(sep)) {
                if (sep->se_ops == &proc_wapt_ops &&
                    mdb_list_next(&sep->se_velist) != NULL &&
                    pt_wparg_overlap(wp, sep->se_data))
                        goto dup;
        }

        for (sep = mdb_list_next(&t->t_idle); sep; sep = mdb_list_next(sep)) {
                if (sep->se_ops == &proc_wapt_ops && pt_wparg_overlap(wp,
                    ((mdb_vespec_t *)mdb_list_next(&sep->se_velist))->ve_args))
                        goto dup;
        }

        return (mdb_tgt_vespec_insert(t, &proc_wapt_ops, spec_flags,
            func, data, wp, pt_wparg_dtor));

dup:
        mdb_free(wp, sizeof (prwatch_t));
        (void) set_errno(EMDB_WPDUP);
        return (0);
}

static int
pt_add_sysenter(mdb_tgt_t *t, int sysnum,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        if (sysnum <= 0 || sysnum > PRMAXSYS) {
                (void) set_errno(EMDB_BADSYSNUM);
                return (0);
        }

        return (mdb_tgt_vespec_insert(t, &proc_sysenter_ops, spec_flags,
            func, data, (void *)(uintptr_t)sysnum, no_ve_dtor));
}

static int
pt_add_sysexit(mdb_tgt_t *t, int sysnum,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        if (sysnum <= 0 || sysnum > PRMAXSYS) {
                (void) set_errno(EMDB_BADSYSNUM);
                return (0);
        }

        return (mdb_tgt_vespec_insert(t, &proc_sysexit_ops, spec_flags,
            func, data, (void *)(uintptr_t)sysnum, no_ve_dtor));
}

static int
pt_add_signal(mdb_tgt_t *t, int signum,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        pt_data_t *pt = t->t_data;

        if (signum <= 0 || signum > pt->p_maxsig) {
                (void) set_errno(EMDB_BADSIGNUM);
                return (0);
        }

        return (mdb_tgt_vespec_insert(t, &proc_signal_ops, spec_flags,
            func, data, (void *)(uintptr_t)signum, no_ve_dtor));
}

static int
pt_add_fault(mdb_tgt_t *t, int fltnum,
    int spec_flags, mdb_tgt_se_f *func, void *data)
{
        if (fltnum <= 0 || fltnum > PRMAXFAULT) {
                (void) set_errno(EMDB_BADFLTNUM);
                return (0);
        }

        return (mdb_tgt_vespec_insert(t, &proc_fault_ops, spec_flags,
            func, data, (void *)(uintptr_t)fltnum, no_ve_dtor));
}

static int
pt_getareg(mdb_tgt_t *t, mdb_tgt_tid_t tid,
    const char *rname, mdb_tgt_reg_t *rp)
{
        pt_data_t *pt = t->t_data;
        prgregset_t grs;
        mdb_var_t *v;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((v = mdb_nv_lookup(&pt->p_regs, rname)) != NULL) {
                uintmax_t rd_nval = mdb_nv_get_value(v);
                ushort_t rd_num = MDB_TGT_R_NUM(rd_nval);
                ushort_t rd_flags = MDB_TGT_R_FLAGS(rd_nval);

                if (!MDB_TGT_R_IS_FP(rd_flags)) {
                        mdb_tgt_reg_t r = 0;

#if defined(__sparc) && defined(_ILP32)
                        /*
                         * If we are debugging on 32-bit SPARC, the globals and
                         * outs can have 32 upper bits hiding in the xregs.
                         */
                        /* gcc doesn't like >= R_G0 because R_G0 == 0 */
                        int is_g = (rd_num == R_G0 ||
                            rd_num >= R_G1 && rd_num <= R_G7);
                        int is_o = (rd_num >= R_O0 && rd_num <= R_O7);
                        prxregset_t xrs;

                        if (is_g && PTL_GETXREGS(t, tid, &xrs) == 0 &&
                            xrs.pr_type == XR_TYPE_V8P) {
                                r |= (uint64_t)xrs.pr_un.pr_v8p.pr_xg[
                                    rd_num - R_G0 + XR_G0] << 32;
                        }

                        if (is_o && PTL_GETXREGS(t, tid, &xrs) == 0 &&
                            xrs.pr_type == XR_TYPE_V8P) {
                                r |= (uint64_t)xrs.pr_un.pr_v8p.pr_xo[
                                    rd_num - R_O0 + XR_O0] << 32;
                        }
#endif  /* __sparc && _ILP32 */

                        /*
                         * Avoid sign-extension by casting: recall that procfs
                         * defines prgreg_t as a long or int and our native
                         * register handling uses uint64_t's.
                         */
                        if (PTL_GETREGS(t, tid, grs) == 0) {
                                *rp = r | (ulong_t)grs[rd_num];
                                if (rd_flags & MDB_TGT_R_32)
                                        *rp &= 0xffffffffULL;
                                else if (rd_flags & MDB_TGT_R_16)
                                        *rp &= 0xffffULL;
                                else if (rd_flags & MDB_TGT_R_8H)
                                        *rp = (*rp & 0xff00ULL) >> 8;
                                else if (rd_flags & MDB_TGT_R_8L)
                                        *rp &= 0xffULL;
                                return (0);
                        }
                        return (-1);
                } else
                        return (pt_getfpreg(t, tid, rd_num, rd_flags, rp));
        }

        return (set_errno(EMDB_BADREG));
}

static int
pt_putareg(mdb_tgt_t *t, mdb_tgt_tid_t tid, const char *rname, mdb_tgt_reg_t r)
{
        pt_data_t *pt = t->t_data;
        prgregset_t grs;
        mdb_var_t *v;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((v = mdb_nv_lookup(&pt->p_regs, rname)) != NULL) {
                uintmax_t rd_nval = mdb_nv_get_value(v);
                ushort_t rd_num = MDB_TGT_R_NUM(rd_nval);
                ushort_t rd_flags = MDB_TGT_R_FLAGS(rd_nval);

                if (!MDB_TGT_R_IS_FP(rd_flags)) {

                        if (rd_flags & MDB_TGT_R_32)
                                r &= 0xffffffffULL;
                        else if (rd_flags & MDB_TGT_R_16)
                                r &= 0xffffULL;
                        else if (rd_flags & MDB_TGT_R_8H)
                                r = (r & 0xffULL) << 8;
                        else if (rd_flags & MDB_TGT_R_8L)
                                r &= 0xffULL;

#if defined(__sparc) && defined(_ILP32)
                        /*
                         * If we are debugging on 32-bit SPARC, the globals and
                         * outs can have 32 upper bits stored in the xregs.
                         */
                        int is_g = (rd_num == R_G0 ||
                            rd_num >= R_G1 && rd_num <= R_G7);
                        int is_o = (rd_num >= R_O0 && rd_num <= R_O7);
                        prxregset_t xrs;

                        if ((is_g || is_o) && PTL_GETXREGS(t, tid, &xrs) == 0 &&
                            xrs.pr_type == XR_TYPE_V8P) {
                                if (is_g) {
                                        xrs.pr_un.pr_v8p.pr_xg[rd_num -
                                            R_G0 + XR_G0] = (uint32_t)(r >> 32);
                                } else if (is_o) {
                                        xrs.pr_un.pr_v8p.pr_xo[rd_num -
                                            R_O0 + XR_O0] = (uint32_t)(r >> 32);
                                }

                                if (PTL_SETXREGS(t, tid, &xrs) == -1)
                                        return (-1);
                        }
#endif  /* __sparc && _ILP32 */

                        if (PTL_GETREGS(t, tid, grs) == 0) {
                                grs[rd_num] = (prgreg_t)r;
                                return (PTL_SETREGS(t, tid, grs));
                        }
                        return (-1);
                } else
                        return (pt_putfpreg(t, tid, rd_num, rd_flags, r));
        }

        return (set_errno(EMDB_BADREG));
}

static int
pt_stack_call(pt_stkarg_t *psp, const prgregset_t grs, uint_t argc, long *argv)
{
        psp->pstk_gotpc |= (grs[R_PC] != 0);

        if (!psp->pstk_gotpc)
                return (0); /* skip initial zeroed frames */

        return (psp->pstk_func(psp->pstk_private, grs[R_PC],
            argc, argv, (const struct mdb_tgt_gregset *)grs));
}

static int
pt_stack_iter(mdb_tgt_t *t, const mdb_tgt_gregset_t *gsp,
    mdb_tgt_stack_f *func, void *arg)
{
        if (t->t_pshandle != NULL) {
                pt_stkarg_t pstk;

                pstk.pstk_func = func;
                pstk.pstk_private = arg;
                pstk.pstk_gotpc = FALSE;

                (void) Pstack_iter(t->t_pshandle, gsp->gregs,
                    (proc_stack_f *)pt_stack_call, &pstk);

                return (0);
        }

        return (set_errno(EMDB_NOPROC));
}

static int
pt_auxv(mdb_tgt_t *t, const auxv_t **auxvp)
{
        if (t->t_pshandle != NULL) {
                *auxvp = Pgetauxvec(t->t_pshandle);
                return (0);
        }

        return (set_errno(EMDB_NOPROC));
}


static const mdb_tgt_ops_t proc_ops = {
        pt_setflags,                            /* t_setflags */
        (int (*)()) mdb_tgt_notsup,             /* t_setcontext */
        pt_activate,                            /* t_activate */
        pt_deactivate,                          /* t_deactivate */
        pt_periodic,                            /* t_periodic */
        pt_destroy,                             /* t_destroy */
        pt_name,                                /* t_name */
        (const char *(*)()) mdb_conf_isa,       /* t_isa */
        pt_platform,                            /* t_platform */
        pt_uname,                               /* t_uname */
        pt_dmodel,                              /* t_dmodel */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_aread */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_awrite */
        pt_vread,                               /* t_vread */
        pt_vwrite,                              /* t_vwrite */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_pread */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_pwrite */
        pt_fread,                               /* t_fread */
        pt_fwrite,                              /* t_fwrite */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_ioread */
        (ssize_t (*)()) mdb_tgt_notsup,         /* t_iowrite */
        (int (*)()) mdb_tgt_notsup,             /* t_vtop */
        pt_lookup_by_name,                      /* t_lookup_by_name */
        pt_lookup_by_addr,                      /* t_lookup_by_addr */
        pt_symbol_iter,                         /* t_symbol_iter */
        pt_mapping_iter,                        /* t_mapping_iter */
        pt_object_iter,                         /* t_object_iter */
        pt_addr_to_map,                         /* t_addr_to_map */
        pt_name_to_map,                         /* t_name_to_map */
        pt_addr_to_ctf,                         /* t_addr_to_ctf */
        pt_name_to_ctf,                         /* t_name_to_ctf */
        pt_status,                              /* t_status */
        pt_run,                                 /* t_run */
        pt_step,                                /* t_step */
        pt_step_out,                            /* t_step_out */
        pt_next,                                /* t_next */
        pt_continue,                            /* t_cont */
        pt_signal,                              /* t_signal */
        pt_add_vbrkpt,                          /* t_add_vbrkpt */
        pt_add_sbrkpt,                          /* t_add_sbrkpt */
        (int (*)()) mdb_tgt_null,               /* t_add_pwapt */
        pt_add_vwapt,                           /* t_add_vwapt */
        (int (*)()) mdb_tgt_null,               /* t_add_iowapt */
        pt_add_sysenter,                        /* t_add_sysenter */
        pt_add_sysexit,                         /* t_add_sysexit */
        pt_add_signal,                          /* t_add_signal */
        pt_add_fault,                           /* t_add_fault */
        pt_getareg,                             /* t_getareg */
        pt_putareg,                             /* t_putareg */
        pt_stack_iter,                          /* t_stack_iter */
        pt_auxv                                 /* t_auxv */
};

/*
 * Utility function for converting libproc errno values to mdb error values
 * for the ptl calls below.  Currently, we only need to convert ENOENT to
 * EMDB_NOTHREAD to produce a more useful error message for the user.
 */
static int
ptl_err(int error)
{
        if (error != 0 && errno == ENOENT)
                return (set_errno(EMDB_NOTHREAD));

        return (error);
}

/*ARGSUSED*/
static mdb_tgt_tid_t
pt_lwp_tid(mdb_tgt_t *t, void *tap)
{
        if (t->t_pshandle != NULL)
                return (Pstatus(t->t_pshandle)->pr_lwp.pr_lwpid);

        return (set_errno(EMDB_NOPROC));
}

static int
pt_lwp_add(mdb_addrvec_t *ap, const lwpstatus_t *psp)
{
        mdb_addrvec_unshift(ap, psp->pr_lwpid);
        return (0);
}

/*ARGSUSED*/
static int
pt_lwp_iter(mdb_tgt_t *t, void *tap, mdb_addrvec_t *ap)
{
        if (t->t_pshandle != NULL)
                return (Plwp_iter(t->t_pshandle, (proc_lwp_f *)pt_lwp_add, ap));

        return (set_errno(EMDB_NOPROC));
}

/*ARGSUSED*/
static int
pt_lwp_getregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prgregset_t gregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_getregs(t->t_pshandle,
                    (lwpid_t)tid, gregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

/*ARGSUSED*/
static int
pt_lwp_setregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prgregset_t gregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_setregs(t->t_pshandle,
                    (lwpid_t)tid, gregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

#ifdef  __sparc

/*ARGSUSED*/
static int
pt_lwp_getxregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prxregset_t *xregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_getxregs(t->t_pshandle,
                    (lwpid_t)tid, xregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

/*ARGSUSED*/
static int
pt_lwp_setxregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    const prxregset_t *xregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_setxregs(t->t_pshandle,
                    (lwpid_t)tid, xregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

#endif  /* __sparc */

/*ARGSUSED*/
static int
pt_lwp_getfpregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    prfpregset_t *fpregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_getfpregs(t->t_pshandle,
                    (lwpid_t)tid, fpregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

/*ARGSUSED*/
static int
pt_lwp_setfpregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    const prfpregset_t *fpregs)
{
        if (t->t_pshandle != NULL) {
                return (ptl_err(Plwp_setfpregs(t->t_pshandle,
                    (lwpid_t)tid, fpregs)));
        }
        return (set_errno(EMDB_NOPROC));
}

static const pt_ptl_ops_t proc_lwp_ops = {
        (int (*)()) mdb_tgt_nop,
        (void (*)()) mdb_tgt_nop,
        pt_lwp_tid,
        pt_lwp_iter,
        pt_lwp_getregs,
        pt_lwp_setregs,
#ifdef __sparc
        pt_lwp_getxregs,
        pt_lwp_setxregs,
#endif
        pt_lwp_getfpregs,
        pt_lwp_setfpregs
};

static int
pt_tdb_ctor(mdb_tgt_t *t)
{
        pt_data_t *pt = t->t_data;
        td_thragent_t *tap;
        td_err_e err;

        if ((err = pt->p_tdb_ops->td_ta_new(t->t_pshandle, &tap)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        pt->p_ptl_hdl = tap;
        return (0);
}

static void
pt_tdb_dtor(mdb_tgt_t *t, void *tap)
{
        pt_data_t *pt = t->t_data;

        ASSERT(tap == pt->p_ptl_hdl);
        (void) pt->p_tdb_ops->td_ta_delete(tap);
        pt->p_ptl_hdl = NULL;
}

static mdb_tgt_tid_t
pt_tdb_tid(mdb_tgt_t *t, void *tap)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_thrinfo_t ti;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_lwp2thr(tap,
            Pstatus(t->t_pshandle)->pr_lwp.pr_lwpid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        if ((err = pt->p_tdb_ops->td_thr_get_info(&th, &ti)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        return (ti.ti_tid);
}

static int
pt_tdb_add(const td_thrhandle_t *thp, pt_addarg_t *pap)
{
        td_thrinfo_t ti;

        if (pap->pa_pt->p_tdb_ops->td_thr_get_info(thp, &ti) == TD_OK &&
            ti.ti_state != TD_THR_ZOMBIE)
                mdb_addrvec_unshift(pap->pa_ap, ti.ti_tid);

        return (0);
}

static int
pt_tdb_iter(mdb_tgt_t *t, void *tap, mdb_addrvec_t *ap)
{
        pt_data_t *pt = t->t_data;
        pt_addarg_t arg;
        int err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        arg.pa_pt = pt;
        arg.pa_ap = ap;

        if ((err = pt->p_tdb_ops->td_ta_thr_iter(tap, (td_thr_iter_f *)
            pt_tdb_add, &arg, TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
            TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

static int
pt_tdb_getregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prgregset_t gregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_getgregs(&th, gregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

static int
pt_tdb_setregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prgregset_t gregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_setgregs(&th, gregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

#ifdef __sparc

static int
pt_tdb_getxregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid, prxregset_t *xregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_getxregs(&th, xregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

static int
pt_tdb_setxregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    const prxregset_t *xregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_setxregs(&th, xregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

#endif  /* __sparc */

static int
pt_tdb_getfpregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    prfpregset_t *fpregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_getfpregs(&th, fpregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

static int
pt_tdb_setfpregs(mdb_tgt_t *t, void *tap, mdb_tgt_tid_t tid,
    const prfpregset_t *fpregs)
{
        pt_data_t *pt = t->t_data;

        td_thrhandle_t th;
        td_err_e err;

        if (t->t_pshandle == NULL)
                return (set_errno(EMDB_NOPROC));

        if ((err = pt->p_tdb_ops->td_ta_map_id2thr(tap, tid, &th)) != TD_OK)
                return (set_errno(tdb_to_errno(err)));

        err = pt->p_tdb_ops->td_thr_setfpregs(&th, fpregs);
        if (err != TD_OK && err != TD_PARTIALREG)
                return (set_errno(tdb_to_errno(err)));

        return (0);
}

static const pt_ptl_ops_t proc_tdb_ops = {
        pt_tdb_ctor,
        pt_tdb_dtor,
        pt_tdb_tid,
        pt_tdb_iter,
        pt_tdb_getregs,
        pt_tdb_setregs,
#ifdef __sparc
        pt_tdb_getxregs,
        pt_tdb_setxregs,
#endif
        pt_tdb_getfpregs,
        pt_tdb_setfpregs
};

static ssize_t
pt_xd_auxv(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        struct ps_prochandle *P = t->t_pshandle;
        const auxv_t *auxp, *auxv = NULL;
        int auxn = 0;

        if (P != NULL && (auxv = Pgetauxvec(P)) != NULL &&
            auxv->a_type != AT_NULL) {
                for (auxp = auxv, auxn = 1; auxp->a_type != NULL; auxp++)
                        auxn++;
        }

        if (buf == NULL && nbytes == 0)
                return (sizeof (auxv_t) * auxn);

        if (auxn == 0)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, sizeof (auxv_t) * auxn);
        bcopy(auxv, buf, nbytes);
        return (nbytes);
}

static ssize_t
pt_xd_cred(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        prcred_t cr, *crp;
        size_t cbytes = 0;

        if (t->t_pshandle != NULL && Pcred(t->t_pshandle, &cr, 1) == 0) {
                cbytes = (cr.pr_ngroups <= 1) ? sizeof (prcred_t) :
                    (sizeof (prcred_t) + (cr.pr_ngroups - 1) * sizeof (gid_t));
        }

        if (buf == NULL && nbytes == 0)
                return (cbytes);

        if (cbytes == 0)
                return (set_errno(ENODATA));

        crp = mdb_alloc(cbytes, UM_SLEEP);

        if (Pcred(t->t_pshandle, crp, cr.pr_ngroups) == -1)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, cbytes);
        bcopy(crp, buf, nbytes);
        mdb_free(crp, cbytes);
        return (nbytes);
}

static ssize_t
pt_xd_ehdr(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        pt_data_t *pt = t->t_data;

        if (buf == NULL && nbytes == 0)
                return (sizeof (GElf_Ehdr));

        if (pt->p_file == NULL)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, sizeof (GElf_Ehdr));
        bcopy(&pt->p_file->gf_ehdr, buf, nbytes);
        return (nbytes);
}

static int
pt_copy_lwp(lwpstatus_t **lspp, const lwpstatus_t *lsp)
{
        bcopy(lsp, *lspp, sizeof (lwpstatus_t));
        (*lspp)++;
        return (0);
}

static ssize_t
pt_xd_lwpstatus(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        lwpstatus_t *lsp, *lbuf;
        const pstatus_t *psp;
        int nlwp = 0;

        if (t->t_pshandle != NULL && (psp = Pstatus(t->t_pshandle)) != NULL)
                nlwp = psp->pr_nlwp;

        if (buf == NULL && nbytes == 0)
                return (sizeof (lwpstatus_t) * nlwp);

        if (nlwp == 0)
                return (set_errno(ENODATA));

        lsp = lbuf = mdb_alloc(sizeof (lwpstatus_t) * nlwp, UM_SLEEP);
        nbytes = MIN(nbytes, sizeof (lwpstatus_t) * nlwp);

        (void) Plwp_iter(t->t_pshandle, (proc_lwp_f *)pt_copy_lwp, &lsp);
        bcopy(lbuf, buf, nbytes);

        mdb_free(lbuf, sizeof (lwpstatus_t) * nlwp);
        return (nbytes);
}

static ssize_t
pt_xd_pshandle(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        if (buf == NULL && nbytes == 0)
                return (sizeof (struct ps_prochandle *));

        if (t->t_pshandle == NULL || nbytes != sizeof (struct ps_prochandle *))
                return (set_errno(ENODATA));

        bcopy(&t->t_pshandle, buf, nbytes);
        return (nbytes);
}

static ssize_t
pt_xd_psinfo(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        const psinfo_t *psp;

        if (buf == NULL && nbytes == 0)
                return (sizeof (psinfo_t));

        if (t->t_pshandle == NULL || (psp = Ppsinfo(t->t_pshandle)) == NULL)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, sizeof (psinfo_t));
        bcopy(psp, buf, nbytes);
        return (nbytes);
}

static ssize_t
pt_xd_pstatus(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        const pstatus_t *psp;

        if (buf == NULL && nbytes == 0)
                return (sizeof (pstatus_t));

        if (t->t_pshandle == NULL || (psp = Pstatus(t->t_pshandle)) == NULL)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, sizeof (pstatus_t));
        bcopy(psp, buf, nbytes);
        return (nbytes);
}

static ssize_t
pt_xd_utsname(mdb_tgt_t *t, void *buf, size_t nbytes)
{
        struct utsname uts;

        if (buf == NULL && nbytes == 0)
                return (sizeof (struct utsname));

        if (t->t_pshandle == NULL || Puname(t->t_pshandle, &uts) != 0)
                return (set_errno(ENODATA));

        nbytes = MIN(nbytes, sizeof (struct utsname));
        bcopy(&uts, buf, nbytes);
        return (nbytes);
}

int
mdb_proc_tgt_create(mdb_tgt_t *t, int argc, const char *argv[])
{
        pt_data_t *pt = mdb_zalloc(sizeof (pt_data_t), UM_SLEEP);

        const char *aout_path = argc > 0 ? argv[0] : PT_EXEC_PATH;
        const char *core_path = argc > 1 ? argv[1] : NULL;

        const mdb_tgt_regdesc_t *rdp;
        char execname[MAXPATHLEN];
        struct stat64 st;
        int perr;
        int state;
        struct rlimit rlim;
        int i;

        if (argc > 2) {
                mdb_free(pt, sizeof (pt_data_t));
                return (set_errno(EINVAL));
        }

        if (t->t_flags & MDB_TGT_F_RDWR)
                pt->p_oflags = O_RDWR;
        else
                pt->p_oflags = O_RDONLY;

        if (t->t_flags & MDB_TGT_F_FORCE)
                pt->p_gflags |= PGRAB_FORCE;
        if (t->t_flags & MDB_TGT_F_NOSTOP)
                pt->p_gflags |= PGRAB_NOSTOP;

        pt->p_ptl_ops = &proc_lwp_ops;
        pt->p_maxsig = sysconf(_SC_SIGRT_MAX);

        (void) mdb_nv_create(&pt->p_regs, UM_SLEEP);
        (void) mdb_nv_create(&pt->p_env, UM_SLEEP);

        t->t_ops = &proc_ops;
        t->t_data = pt;

        /*
         * If no core file name was specified, but the file ./core is present,
         * infer that we want to debug it.  I find this behavior confusing,
         * so we only do this when precise adb(1) compatibility is required.
         */
        if (core_path == NULL && (mdb.m_flags & MDB_FL_ADB) &&
            access(PT_CORE_PATH, F_OK) == 0)
                core_path = PT_CORE_PATH;

        /*
         * For compatibility with adb(1), the special name "-" may be used
         * to suppress the loading of the executable or core file.
         */
        if (aout_path != NULL && strcmp(aout_path, "-") == 0)
                aout_path = NULL;
        if (core_path != NULL && strcmp(core_path, "-") == 0)
                core_path = NULL;

        /*
         * If a core file or pid was specified, attempt to grab it now using
         * proc_arg_grab(); otherwise we'll create a fresh process later.
         */
        if (core_path != NULL && (t->t_pshandle = proc_arg_xgrab(core_path,
            aout_path == PT_EXEC_PATH ? NULL : aout_path, PR_ARG_ANY,
            pt->p_gflags, &perr, NULL)) == NULL) {
                mdb_warn("cannot debug %s: %s\n", core_path, Pgrab_error(perr));
                goto err;
        }

        if (aout_path != NULL &&
            (pt->p_idlehandle = Pgrab_file(aout_path, &perr)) != NULL &&
            t->t_pshandle == NULL)
                t->t_pshandle = pt->p_idlehandle;

        if (t->t_pshandle != NULL)
                state = Pstate(t->t_pshandle);

        /*
         * Make sure we'll have enough file descriptors to handle a target
         * has many many mappings.
         */
        if (getrlimit(RLIMIT_NOFILE, &rlim) == 0) {
                rlim.rlim_cur = rlim.rlim_max;
                (void) setrlimit(RLIMIT_NOFILE, &rlim);
                (void) enable_extended_FILE_stdio(-1, -1);
        }

        /*
         * If we don't have an executable path or the executable path is the
         * /proc/<pid>/object/a.out path, but we now have a libproc handle,
         * attempt to derive the executable path using Pexecname().  We need
         * to do this in the /proc case in order to open the executable for
         * writing because /proc/object/<file> permission are masked with 0555.
         * If Pexecname() fails us, fall back to /proc/<pid>/object/a.out.
         */
        if (t->t_pshandle != NULL && (aout_path == NULL || (stat64(aout_path,
            &st) == 0 && strcmp(st.st_fstype, "proc") == 0))) {
                GElf_Sym s;
                aout_path = Pexecname(t->t_pshandle, execname, MAXPATHLEN);
                if (aout_path == NULL && state != PS_DEAD && state != PS_IDLE) {
                        (void) mdb_iob_snprintf(execname, sizeof (execname),
                            "/proc/%d/object/a.out",
                            (int)Pstatus(t->t_pshandle)->pr_pid);
                        aout_path = execname;
                }
                if (aout_path == NULL &&
                    Plookup_by_name(t->t_pshandle, "a.out", "_start", &s) != 0)
                        mdb_warn("warning: failed to infer pathname to "
                            "executable; symbol table will not be available\n");

                mdb_dprintf(MDB_DBG_TGT, "a.out is %s\n", aout_path);
        }

        /*
         * Attempt to open the executable file.  We only want this operation
         * to actually cause the constructor to abort if the executable file
         * name was given explicitly.  If we defaulted to PT_EXEC_PATH or
         * derived the executable using Pexecname, then we want to continue
         * along with p_fio and p_file set to NULL.
         */
        if (aout_path != NULL && (pt->p_aout_fio = mdb_fdio_create_path(NULL,
            aout_path, pt->p_oflags, 0)) == NULL && argc > 0) {
                mdb_warn("failed to open %s", aout_path);
                goto err;
        }

        /*
         * Now create an ELF file from the input file, if we have one.  Again,
         * only abort the constructor if the name was given explicitly.
         */
        if (pt->p_aout_fio != NULL && pt_open_aout(t,
            mdb_io_hold(pt->p_aout_fio)) == NULL && argc > 0)
                goto err;

        /*
         * If we've successfully opened an ELF file, select the appropriate
         * disassembler based on the ELF header.
         */
        if (pt->p_file != NULL)
                (void) mdb_dis_select(pt_disasm(&pt->p_file->gf_ehdr));
        else
                (void) mdb_dis_select(pt_disasm(NULL));

        /*
         * Add each register described in the target ISA register description
         * list to our hash table of register descriptions and then add any
         * appropriate ISA-specific floating-point register descriptions.
         */
        for (rdp = pt_regdesc; rdp->rd_name != NULL; rdp++) {
                (void) mdb_nv_insert(&pt->p_regs, rdp->rd_name, NULL,
                    MDB_TGT_R_NVAL(rdp->rd_num, rdp->rd_flags), MDB_NV_RDONLY);
        }
        pt_addfpregs(t);

        /*
         * Certain important /proc structures may be of interest to mdb
         * modules and their dcmds.  Export these using the xdata interface:
         */
        (void) mdb_tgt_xdata_insert(t, "auxv",
            "procfs auxv_t array", pt_xd_auxv);
        (void) mdb_tgt_xdata_insert(t, "cred",
            "procfs prcred_t structure", pt_xd_cred);
        (void) mdb_tgt_xdata_insert(t, "ehdr",
            "executable file GElf_Ehdr structure", pt_xd_ehdr);
        (void) mdb_tgt_xdata_insert(t, "lwpstatus",
            "procfs lwpstatus_t array", pt_xd_lwpstatus);
        (void) mdb_tgt_xdata_insert(t, "pshandle",
            "libproc proc service API handle", pt_xd_pshandle);
        (void) mdb_tgt_xdata_insert(t, "psinfo",
            "procfs psinfo_t structure", pt_xd_psinfo);
        (void) mdb_tgt_xdata_insert(t, "pstatus",
            "procfs pstatus_t structure", pt_xd_pstatus);
        (void) mdb_tgt_xdata_insert(t, "utsname",
            "utsname structure", pt_xd_utsname);

        /*
         * Force a status update now so that we fill in t_status with the
         * latest information based on any successful grab.
         */
        (void) mdb_tgt_status(t, &t->t_status);

        /*
         * If we're not examining a core file, trace SIGINT and all signals
         * that cause the process to dump core as part of our initialization.
         */
        if ((t->t_pshandle != NULL && state != PS_DEAD && state != PS_IDLE) ||
            (pt->p_file != NULL && pt->p_file->gf_ehdr.e_type == ET_EXEC)) {

                int tflag = MDB_TGT_SPEC_STICKY; /* default sigs are sticky */

                (void) mdb_tgt_add_signal(t, SIGINT, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGQUIT, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGILL, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGTRAP, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGABRT, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGEMT, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGFPE, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGBUS, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGSEGV, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGSYS, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGXCPU, tflag, no_se_f, NULL);
                (void) mdb_tgt_add_signal(t, SIGXFSZ, tflag, no_se_f, NULL);
        }

        /*
         * If we've grabbed a live process, establish our initial breakpoints
         * and librtld_db agent so we can track rtld activity.  If FL_VCREATE
         * is set, this process was created by a previous instantiation of
         * the debugger, so reset pr_flags to kill it; otherwise we attached
         * to an already running process.  Pgrab() has already set the PR_RLC
         * flag appropriately based on whether the process was stopped when we
         * attached.
         */
        if (t->t_pshandle != NULL && state != PS_DEAD && state != PS_IDLE) {
                if (mdb.m_flags & MDB_FL_VCREATE) {
                        (void) Punsetflags(t->t_pshandle, PR_RLC);
                        (void) Psetflags(t->t_pshandle, PR_KLC);
                        pt->p_rflags = PRELEASE_KILL;
                } else {
                        (void) Punsetflags(t->t_pshandle, PR_KLC);
                }
                pt_post_attach(t);
        }

        /*
         * Initialize a local copy of the environment, which can be modified
         * before running the program.
         */
        for (i = 0; mdb.m_env[i] != NULL; i++)
                pt_env_set(pt, mdb.m_env[i]);

        /*
         * If adb(1) compatibility mode is on, then print the appropriate
         * greeting message if we have grabbed a core file.
         */
        if ((mdb.m_flags & MDB_FL_ADB) && t->t_pshandle != NULL &&
            state == PS_DEAD) {
                const pstatus_t *psp = Pstatus(t->t_pshandle);
                int cursig = psp->pr_lwp.pr_cursig;
                char signame[SIG2STR_MAX];

                mdb_printf("core file = %s -- program ``%s'' on platform %s\n",
                    core_path, aout_path ? aout_path : "?", pt_platform(t));

                if (cursig != 0 && sig2str(cursig, signame) == 0)
                        mdb_printf("SIG%s: %s\n", signame, strsignal(cursig));
        }

        return (0);

err:
        pt_destroy(t);
        return (-1);
}