makeroot: zero out subsecond component of time= keywords

[freebsd-src.git] / lib / libkvm / kvm.c

/*-
 * Copyright (c) 1989, 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software developed by the Computer Systems
 * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
 * BG 91-66 and contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)kvm.c       8.2 (Berkeley) 2/13/94";
#endif
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/fnv_hash.h>

#define _WANT_VNET

#include <sys/user.h>
#include <sys/linker.h>
#include <sys/pcpu.h>
#include <sys/stat.h>

#include <net/vnet.h>

#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <paths.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "kvm_private.h"

SET_DECLARE(kvm_arch, struct kvm_arch);

/* from src/lib/libc/gen/nlist.c */
int __fdnlist(int, struct nlist *);

static int
kvm_fdnlist(kvm_t *kd, struct kvm_nlist *list)
{
        kvaddr_t addr;
        int error, nfail;

        if (kd->resolve_symbol == NULL) {
                struct nlist *nl;
                int count, i;

                for (count = 0; list[count].n_name != NULL &&
                     list[count].n_name[0] != '\0'; count++)
                        ;
                nl = calloc(count + 1, sizeof(*nl));
                for (i = 0; i < count; i++)
                        nl[i].n_name = list[i].n_name;
                nfail = __fdnlist(kd->nlfd, nl);
                for (i = 0; i < count; i++) {
                        list[i].n_type = nl[i].n_type;
                        list[i].n_value = nl[i].n_value;
                }
                free(nl);
                return (nfail);
        }

        nfail = 0;
        while (list->n_name != NULL && list->n_name[0] != '\0') {
                error = kd->resolve_symbol(list->n_name, &addr);
                if (error != 0) {
                        nfail++;
                        list->n_value = 0;
                        list->n_type = 0;
                } else {
                        list->n_value = addr;
                        list->n_type = N_DATA | N_EXT;
                }
                list++;
        }
        return (nfail);
}

char *
kvm_geterr(kvm_t *kd)
{
        return (kd->errbuf);
}

#include <stdarg.h>

/*
 * Report an error using printf style arguments.  "program" is kd->program
 * on hard errors, and 0 on soft errors, so that under sun error emulation,
 * only hard errors are printed out (otherwise, programs like gdb will
 * generate tons of error messages when trying to access bogus pointers).
 */
void
_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        if (program != NULL) {
                (void)fprintf(stderr, "%s: ", program);
                (void)vfprintf(stderr, fmt, ap);
                (void)fputc('\n', stderr);
        } else
                (void)vsnprintf(kd->errbuf,
                    sizeof(kd->errbuf), fmt, ap);

        va_end(ap);
}

void
_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
{
        va_list ap;
        int n;

        va_start(ap, fmt);
        if (program != NULL) {
                (void)fprintf(stderr, "%s: ", program);
                (void)vfprintf(stderr, fmt, ap);
                (void)fprintf(stderr, ": %s\n", strerror(errno));
        } else {
                char *cp = kd->errbuf;

                (void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap);
                n = strlen(cp);
                (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
                    strerror(errno));
        }
        va_end(ap);
}

void *
_kvm_malloc(kvm_t *kd, size_t n)
{
        void *p;

        if ((p = calloc(n, sizeof(char))) == NULL)
                _kvm_err(kd, kd->program, "can't allocate %zu bytes: %s",
                         n, strerror(errno));
        return (p);
}

static int
_kvm_read_kernel_ehdr(kvm_t *kd)
{
        Elf *elf;

        if (elf_version(EV_CURRENT) == EV_NONE) {
                _kvm_err(kd, kd->program, "Unsupported libelf");
                return (-1);
        }
        elf = elf_begin(kd->nlfd, ELF_C_READ, NULL);
        if (elf == NULL) {
                _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                return (-1);
        }
        if (elf_kind(elf) != ELF_K_ELF) {
                _kvm_err(kd, kd->program, "kernel is not an ELF file");
                return (-1);
        }
        if (gelf_getehdr(elf, &kd->nlehdr) == NULL) {
                _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                elf_end(elf);
                return (-1);
        }
        elf_end(elf);

        switch (kd->nlehdr.e_ident[EI_DATA]) {
        case ELFDATA2LSB:
        case ELFDATA2MSB:
                return (0);
        default:
                _kvm_err(kd, kd->program,
                    "unsupported ELF data encoding for kernel");
                return (-1);
        }
}

int
_kvm_probe_elf_kernel(kvm_t *kd, int class, int machine)
{

        return (kd->nlehdr.e_ident[EI_CLASS] == class &&
            kd->nlehdr.e_type == ET_EXEC &&
            kd->nlehdr.e_machine == machine);
}

int
_kvm_is_minidump(kvm_t *kd)
{
        char minihdr[8];

        if (kd->rawdump)
                return (0);
        if (pread(kd->pmfd, &minihdr, 8, 0) == 8 &&
            memcmp(&minihdr, "minidump", 8) == 0)
                return (1);
        return (0);
}

/*
 * The powerpc backend has a hack to strip a leading kerneldump
 * header from the core before treating it as an ELF header.
 *
 * We can add that here if we can get a change to libelf to support
 * an initial offset into the file.  Alternatively we could patch
 * savecore to extract cores from a regular file instead.
 */
int
_kvm_read_core_phdrs(kvm_t *kd, size_t *phnump, GElf_Phdr **phdrp)
{
        GElf_Ehdr ehdr;
        GElf_Phdr *phdr;
        Elf *elf;
        size_t i, phnum;

        elf = elf_begin(kd->pmfd, ELF_C_READ, NULL);
        if (elf == NULL) {
                _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                return (-1);
        }
        if (elf_kind(elf) != ELF_K_ELF) {
                _kvm_err(kd, kd->program, "invalid core");
                goto bad;
        }
        if (gelf_getclass(elf) != kd->nlehdr.e_ident[EI_CLASS]) {
                _kvm_err(kd, kd->program, "invalid core");
                goto bad;
        }
        if (gelf_getehdr(elf, &ehdr) == NULL) {
                _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                goto bad;
        }
        if (ehdr.e_type != ET_CORE) {
                _kvm_err(kd, kd->program, "invalid core");
                goto bad;
        }
        if (ehdr.e_machine != kd->nlehdr.e_machine) {
                _kvm_err(kd, kd->program, "invalid core");
                goto bad;
        }

        if (elf_getphdrnum(elf, &phnum) == -1) {
                _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                goto bad;
        }

        phdr = calloc(phnum, sizeof(*phdr));
        if (phdr == NULL) {
                _kvm_err(kd, kd->program, "failed to allocate phdrs");
                goto bad;
        }

        for (i = 0; i < phnum; i++) {
                if (gelf_getphdr(elf, i, &phdr[i]) == NULL) {
                        _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
                        goto bad;
                }
        }
        elf_end(elf);
        *phnump = phnum;
        *phdrp = phdr;
        return (0);

bad:
        elf_end(elf);
        return (-1);
}

static void
_kvm_hpt_insert(struct hpt *hpt, uint64_t pa, off_t off)
{
        struct hpte *hpte;
        uint32_t fnv = FNV1_32_INIT;

        fnv = fnv_32_buf(&pa, sizeof(pa), fnv);
        fnv &= (HPT_SIZE - 1);
        hpte = malloc(sizeof(*hpte));
        hpte->pa = pa;
        hpte->off = off;
        hpte->next = hpt->hpt_head[fnv];
        hpt->hpt_head[fnv] = hpte;
}

void
_kvm_hpt_init(kvm_t *kd, struct hpt *hpt, void *base, size_t len, off_t off,
    int page_size, int word_size)
{
        uint64_t bits, idx, pa;
        uint64_t *base64;
        uint32_t *base32;

        base64 = base;
        base32 = base;
        for (idx = 0; idx < len / word_size; idx++) {
                if (word_size == sizeof(uint64_t))
                        bits = _kvm64toh(kd, base64[idx]);
                else
                        bits = _kvm32toh(kd, base32[idx]);
                pa = idx * word_size * NBBY * page_size;
                for (; bits != 0; bits >>= 1, pa += page_size) {
                        if ((bits & 1) == 0)
                                continue;
                        _kvm_hpt_insert(hpt, pa, off);
                        off += page_size;
                }
        }
}

off_t
_kvm_hpt_find(struct hpt *hpt, uint64_t pa)
{
        struct hpte *hpte;
        uint32_t fnv = FNV1_32_INIT;

        fnv = fnv_32_buf(&pa, sizeof(pa), fnv);
        fnv &= (HPT_SIZE - 1);
        for (hpte = hpt->hpt_head[fnv]; hpte != NULL; hpte = hpte->next) {
                if (pa == hpte->pa)
                        return (hpte->off);
        }
        return (-1);
}

void
_kvm_hpt_free(struct hpt *hpt)
{
        struct hpte *hpte, *next;
        int i;

        for (i = 0; i < HPT_SIZE; i++) {
                for (hpte = hpt->hpt_head[i]; hpte != NULL; hpte = next) {
                        next = hpte->next;
                        free(hpte);
                }
        }
}

static kvm_t *
_kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
{
        struct kvm_arch **parch;
        struct stat st;

        kd->vmfd = -1;
        kd->pmfd = -1;
        kd->nlfd = -1;
        kd->vmst = NULL;
        kd->procbase = NULL;
        kd->argspc = NULL;
        kd->argv = NULL;

        if (uf == NULL)
                uf = getbootfile();
        else if (strlen(uf) >= MAXPATHLEN) {
                _kvm_err(kd, kd->program, "exec file name too long");
                goto failed;
        }
        if (flag & ~O_RDWR) {
                _kvm_err(kd, kd->program, "bad flags arg");
                goto failed;
        }
        if (mf == NULL)
                mf = _PATH_MEM;

        if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) {
                _kvm_syserr(kd, kd->program, "%s", mf);
                goto failed;
        }
        if (fstat(kd->pmfd, &st) < 0) {
                _kvm_syserr(kd, kd->program, "%s", mf);
                goto failed;
        }
        if (S_ISREG(st.st_mode) && st.st_size <= 0) {
                errno = EINVAL;
                _kvm_syserr(kd, kd->program, "empty file");
                goto failed;
        }
        if (S_ISCHR(st.st_mode)) {
                /*
                 * If this is a character special device, then check that
                 * it's /dev/mem.  If so, open kmem too.  (Maybe we should
                 * make it work for either /dev/mem or /dev/kmem -- in either
                 * case you're working with a live kernel.)
                 */
                if (strcmp(mf, _PATH_DEVNULL) == 0) {
                        kd->vmfd = open(_PATH_DEVNULL, O_RDONLY | O_CLOEXEC);
                        return (kd);
                } else if (strcmp(mf, _PATH_MEM) == 0) {
                        if ((kd->vmfd = open(_PATH_KMEM, flag | O_CLOEXEC)) <
                            0) {
                                _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
                                goto failed;
                        }
                        return (kd);
                }
        }
        /*
         * This is a crash dump.
         * Open the namelist fd and determine the architecture.
         */
        if ((kd->nlfd = open(uf, O_RDONLY | O_CLOEXEC, 0)) < 0) {
                _kvm_syserr(kd, kd->program, "%s", uf);
                goto failed;
        }
        if (_kvm_read_kernel_ehdr(kd) < 0)
                goto failed;
        if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0)
                kd->rawdump = 1;
        SET_FOREACH(parch, kvm_arch) {
                if ((*parch)->ka_probe(kd)) {
                        kd->arch = *parch;
                        break;
                }
        }
        if (kd->arch == NULL) {
                _kvm_err(kd, kd->program, "unsupported architecture");
                goto failed;
        }

        /*
         * Non-native kernels require a symbol resolver.
         */
        if (!kd->arch->ka_native(kd) && kd->resolve_symbol == NULL) {
                _kvm_err(kd, kd->program,
                    "non-native kernel requires a symbol resolver");
                goto failed;
        }

        /*
         * Initialize the virtual address translation machinery.
         */
        if (kd->arch->ka_initvtop(kd) < 0)
                goto failed;
        return (kd);
failed:
        /*
         * Copy out the error if doing sane error semantics.
         */
        if (errout != NULL)
                strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
        (void)kvm_close(kd);
        return (0);
}

kvm_t *
kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag,
    char *errout)
{
        kvm_t *kd;

        if ((kd = calloc(1, sizeof(*kd))) == NULL) {
                if (errout != NULL)
                        (void)strlcpy(errout, strerror(errno),
                            _POSIX2_LINE_MAX);
                return (0);
        }
        return (_kvm_open(kd, uf, mf, flag, errout));
}

kvm_t *
kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag,
    const char *errstr)
{
        kvm_t *kd;

        if ((kd = calloc(1, sizeof(*kd))) == NULL) {
                if (errstr != NULL)
                        (void)fprintf(stderr, "%s: %s\n",
                                      errstr, strerror(errno));
                return (0);
        }
        kd->program = errstr;
        return (_kvm_open(kd, uf, mf, flag, NULL));
}

kvm_t *
kvm_open2(const char *uf, const char *mf, int flag, char *errout,
    int (*resolver)(const char *, kvaddr_t *))
{
        kvm_t *kd;

        if ((kd = calloc(1, sizeof(*kd))) == NULL) {
                if (errout != NULL)
                        (void)strlcpy(errout, strerror(errno),
                            _POSIX2_LINE_MAX);
                return (0);
        }
        kd->resolve_symbol = resolver;
        return (_kvm_open(kd, uf, mf, flag, errout));
}

int
kvm_close(kvm_t *kd)
{
        int error = 0;

        if (kd->vmst != NULL)
                kd->arch->ka_freevtop(kd);
        if (kd->pmfd >= 0)
                error |= close(kd->pmfd);
        if (kd->vmfd >= 0)
                error |= close(kd->vmfd);
        if (kd->nlfd >= 0)
                error |= close(kd->nlfd);
        if (kd->procbase != 0)
                free((void *)kd->procbase);
        if (kd->argbuf != 0)
                free((void *) kd->argbuf);
        if (kd->argspc != 0)
                free((void *) kd->argspc);
        if (kd->argv != 0)
                free((void *)kd->argv);
        free((void *)kd);

        return (0);
}

/*
 * Walk the list of unresolved symbols, generate a new list and prefix the
 * symbol names, try again, and merge back what we could resolve.
 */
static int
kvm_fdnlist_prefix(kvm_t *kd, struct kvm_nlist *nl, int missing,
    const char *prefix, kvaddr_t (*validate_fn)(kvm_t *, kvaddr_t))
{
        struct kvm_nlist *n, *np, *p;
        char *cp, *ce;
        const char *ccp;
        size_t len;
        int slen, unresolved;

        /*
         * Calculate the space we need to malloc for nlist and names.
         * We are going to store the name twice for later lookups: once
         * with the prefix and once the unmodified name delmited by \0.
         */
        len = 0;
        unresolved = 0;
        for (p = nl; p->n_name && p->n_name[0]; ++p) {
                if (p->n_type != N_UNDF)
                        continue;
                len += sizeof(struct kvm_nlist) + strlen(prefix) +
                    2 * (strlen(p->n_name) + 1);
                unresolved++;
        }
        if (unresolved == 0)
                return (unresolved);
        /* Add space for the terminating nlist entry. */
        len += sizeof(struct kvm_nlist);
        unresolved++;

        /* Alloc one chunk for (nlist, [names]) and setup pointers. */
        n = np = malloc(len);
        bzero(n, len);
        if (n == NULL)
                return (missing);
        cp = ce = (char *)np;
        cp += unresolved * sizeof(struct kvm_nlist);
        ce += len;

        /* Generate shortened nlist with special prefix. */
        unresolved = 0;
        for (p = nl; p->n_name && p->n_name[0]; ++p) {
                if (p->n_type != N_UNDF)
                        continue;
                *np = *p;
                /* Save the new\0orig. name so we can later match it again. */
                slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix,
                    (prefix[0] != '\0' && p->n_name[0] == '_') ?
                        (p->n_name + 1) : p->n_name, '\0', p->n_name);
                if (slen < 0 || slen >= ce - cp)
                        continue;
                np->n_name = cp;
                cp += slen + 1;
                np++;
                unresolved++;
        }

        /* Do lookup on the reduced list. */
        np = n;
        unresolved = kvm_fdnlist(kd, np);

        /* Check if we could resolve further symbols and update the list. */
        if (unresolved >= 0 && unresolved < missing) {
                /* Find the first freshly resolved entry. */
                for (; np->n_name && np->n_name[0]; np++)
                        if (np->n_type != N_UNDF)
                                break;
                /*
                 * The lists are both in the same order,
                 * so we can walk them in parallel.
                 */
                for (p = nl; np->n_name && np->n_name[0] &&
                    p->n_name && p->n_name[0]; ++p) {
                        if (p->n_type != N_UNDF)
                                continue;
                        /* Skip expanded name and compare to orig. one. */
                        ccp = np->n_name + strlen(np->n_name) + 1;
                        if (strcmp(ccp, p->n_name) != 0)
                                continue;
                        /* Update nlist with new, translated results. */
                        p->n_type = np->n_type;
                        if (validate_fn)
                                p->n_value = (*validate_fn)(kd, np->n_value);
                        else
                                p->n_value = np->n_value;
                        missing--;
                        /* Find next freshly resolved entry. */
                        for (np++; np->n_name && np->n_name[0]; np++)
                                if (np->n_type != N_UNDF)
                                        break;
                }
        }
        /* We could assert missing = unresolved here. */

        free(n);
        return (unresolved);
}

int
_kvm_nlist(kvm_t *kd, struct kvm_nlist *nl, int initialize)
{
        struct kvm_nlist *p;
        int nvalid;
        struct kld_sym_lookup lookup;
        int error;
        const char *prefix = "";
        char symname[1024]; /* XXX-BZ symbol name length limit? */
        int tried_vnet, tried_dpcpu;

        /*
         * If we can't use the kld symbol lookup, revert to the
         * slow library call.
         */
        if (!ISALIVE(kd)) {
                error = kvm_fdnlist(kd, nl);
                if (error <= 0)                 /* Hard error or success. */
                        return (error);

                if (_kvm_vnet_initialized(kd, initialize))
                        error = kvm_fdnlist_prefix(kd, nl, error,
                            VNET_SYMPREFIX, _kvm_vnet_validaddr);

                if (error > 0 && _kvm_dpcpu_initialized(kd, initialize))
                        error = kvm_fdnlist_prefix(kd, nl, error,
                            DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr);

                return (error);
        }

        /*
         * We can use the kld lookup syscall.  Go through each nlist entry
         * and look it up with a kldsym(2) syscall.
         */
        nvalid = 0;
        tried_vnet = 0;
        tried_dpcpu = 0;
again:
        for (p = nl; p->n_name && p->n_name[0]; ++p) {
                if (p->n_type != N_UNDF)
                        continue;

                lookup.version = sizeof(lookup);
                lookup.symvalue = 0;
                lookup.symsize = 0;

                error = snprintf(symname, sizeof(symname), "%s%s", prefix,
                    (prefix[0] != '\0' && p->n_name[0] == '_') ?
                        (p->n_name + 1) : p->n_name);
                if (error < 0 || error >= (int)sizeof(symname))
                        continue;
                lookup.symname = symname;
                if (lookup.symname[0] == '_')
                        lookup.symname++;

                if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
                        p->n_type = N_TEXT;
                        if (_kvm_vnet_initialized(kd, initialize) &&
                            strcmp(prefix, VNET_SYMPREFIX) == 0)
                                p->n_value =
                                    _kvm_vnet_validaddr(kd, lookup.symvalue);
                        else if (_kvm_dpcpu_initialized(kd, initialize) &&
                            strcmp(prefix, DPCPU_SYMPREFIX) == 0)
                                p->n_value =
                                    _kvm_dpcpu_validaddr(kd, lookup.symvalue);
                        else
                                p->n_value = lookup.symvalue;
                        ++nvalid;
                        /* lookup.symsize */
                }
        }

        /*
         * Check the number of entries that weren't found. If they exist,
         * try again with a prefix for virtualized or DPCPU symbol names.
         */
        error = ((p - nl) - nvalid);
        if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) {
                tried_vnet = 1;
                prefix = VNET_SYMPREFIX;
                goto again;
        }
        if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) {
                tried_dpcpu = 1;
                prefix = DPCPU_SYMPREFIX;
                goto again;
        }

        /*
         * Return the number of entries that weren't found. If they exist,
         * also fill internal error buffer.
         */
        error = ((p - nl) - nvalid);
        if (error)
                _kvm_syserr(kd, kd->program, "kvm_nlist");
        return (error);
}

int
kvm_nlist2(kvm_t *kd, struct kvm_nlist *nl)
{

        /*
         * If called via the public interface, permit initialization of
         * further virtualized modules on demand.
         */
        return (_kvm_nlist(kd, nl, 1));
}

int
kvm_nlist(kvm_t *kd, struct nlist *nl)
{
        struct kvm_nlist *kl;
        int count, i, nfail;

        /*
         * Avoid reporting truncated addresses by failing for non-native
         * cores.
         */
        if (!kvm_native(kd)) {
                _kvm_err(kd, kd->program, "kvm_nlist of non-native vmcore");
                return (-1);
        }

        for (count = 0; nl[count].n_name != NULL && nl[count].n_name[0] != '\0';
             count++)
                ;
        if (count == 0)
                return (0);
        kl = calloc(count + 1, sizeof(*kl));
        for (i = 0; i < count; i++)
                kl[i].n_name = nl[i].n_name;
        nfail = kvm_nlist2(kd, kl);
        for (i = 0; i < count; i++) {
                nl[i].n_type = kl[i].n_type;
                nl[i].n_other = 0;
                nl[i].n_desc = 0;
                nl[i].n_value = kl[i].n_value;
        }
        return (nfail);
}

ssize_t
kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
{

        return (kvm_read2(kd, kva, buf, len));
}

ssize_t
kvm_read2(kvm_t *kd, kvaddr_t kva, void *buf, size_t len)
{
        int cc;
        ssize_t cr;
        off_t pa;
        char *cp;

        if (ISALIVE(kd)) {
                /*
                 * We're using /dev/kmem.  Just read straight from the
                 * device and let the active kernel do the address translation.
                 */
                errno = 0;
                if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
                        _kvm_err(kd, 0, "invalid address (0x%jx)",
                            (uintmax_t)kva);
                        return (-1);
                }
                cr = read(kd->vmfd, buf, len);
                if (cr < 0) {
                        _kvm_syserr(kd, 0, "kvm_read");
                        return (-1);
                } else if (cr < (ssize_t)len)
                        _kvm_err(kd, kd->program, "short read");
                return (cr);
        }

        cp = buf;
        while (len > 0) {
                cc = kd->arch->ka_kvatop(kd, kva, &pa);
                if (cc == 0)
                        return (-1);
                if (cc > (ssize_t)len)
                        cc = len;
                errno = 0;
                if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
                        _kvm_syserr(kd, 0, _PATH_MEM);
                        break;
                }
                cr = read(kd->pmfd, cp, cc);
                if (cr < 0) {
                        _kvm_syserr(kd, kd->program, "kvm_read");
                        break;
                }
                /*
                 * If ka_kvatop returns a bogus value or our core file is
                 * truncated, we might wind up seeking beyond the end of the
                 * core file in which case the read will return 0 (EOF).
                 */
                if (cr == 0)
                        break;
                cp += cr;
                kva += cr;
                len -= cr;
        }

        return (cp - (char *)buf);
}

ssize_t
kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
{
        int cc;

        if (ISALIVE(kd)) {
                /*
                 * Just like kvm_read, only we write.
                 */
                errno = 0;
                if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
                        _kvm_err(kd, 0, "invalid address (%lx)", kva);
                        return (-1);
                }
                cc = write(kd->vmfd, buf, len);
                if (cc < 0) {
                        _kvm_syserr(kd, 0, "kvm_write");
                        return (-1);
                } else if ((size_t)cc < len)
                        _kvm_err(kd, kd->program, "short write");
                return (cc);
        } else {
                _kvm_err(kd, kd->program,
                    "kvm_write not implemented for dead kernels");
                return (-1);
        }
        /* NOTREACHED */
}

int
kvm_native(kvm_t *kd)
{

        if (ISALIVE(kd))
                return (1);
        return (kd->arch->ka_native(kd));
}