usr.bin/truss/main.c

   1 /*
   2  * Copryight 1997 Sean Eric Fagan
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. All advertising materials mentioning features or use of this software
  13  *    must display the following acknowledgement:
  14  *      This product includes software developed by Sean Eric Fagan
  15  * 4. Neither the name of the author may be used to endorse or promote
  16  *    products derived from this software without specific prior written
  17  *    permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  * $FreeBSD: src/usr.bin/truss/main.c,v 1.15.2.3 2002/05/16 23:41:23 peter Exp $
  32  */
  33
  34 /*
  35  * The main module for truss.  Suprisingly simple, but, then, the other
  36  * files handle the bulk of the work.  And, of course, the kernel has to
  37  * do a lot of the work :).
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/ioctl.h>
  42 #include <sys/pioctl.h>
  43 #include <sys/ucred.h>
  44 #include <sys/mount.h>
  45
  46 #include <err.h>
  47 #include <errno.h>
  48 #include <fcntl.h>
  49 #include <signal.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <unistd.h>
  54
  55 #include "truss.h"
  56 #include "extern.h"
  57
  58 /*
  59  * These should really be parameterized -- I don't like having globals,
  60  * but this is the easiest way, right now, to deal with them.
  61  */
  62
  63 int Procfd;
  64
  65 static void
  66 usage(void)
  67 {
  68   fprintf(stderr, "%s\n%s\n",
  69         "usage: truss [-S] [-o file] -p pid",
  70         "       truss [-S] [-o file] command [args]");
  71   exit(1);
  72 }
  73
  74 struct ex_types {
  75   const char *type;
  76   void (*enter_syscall)(struct trussinfo *, int);
  77   int (*exit_syscall)(struct trussinfo *, int);
  78 } ex_types[] = {
  79 #ifdef __x86_64__
  80   { "DragonFly ELF64", x86_64_syscall_entry, x86_64_syscall_exit },
  81   { "FreeBSD ELF64", x86_64_syscall_entry, x86_64_syscall_exit },
  82 #endif
  83   { 0, 0, 0 },
  84 };
  85
  86 /*
  87  * Set the execution type.  This is called after every exec, and when
  88  * a process is first monitored.  The procfs pseudo-file "etype" has
  89  * the execution module type -- see /proc/curproc/etype for an example.
  90  */
  91
  92 static struct ex_types *
  93 set_etype(struct trussinfo *trussinfo) {
  94   struct ex_types *funcs;
  95   char *etype;
  96   char progt[32];
  97   int fd;
  98
  99   asprintf(&etype, "%s/%d/etype", procfs_path, trussinfo->pid);
 100   if (etype == NULL)
 101     err(1, "Out of memory");
 102   if ((fd = open(etype, O_RDONLY)) == -1) {
 103     strcpy(progt, "FreeBSD a.out");
 104   } else {
 105     int len = read(fd, progt, sizeof(progt));
 106     progt[len-1] = '\0';
 107     close(fd);
 108   }
 109   free(etype);
 110
 111   for (funcs = ex_types; funcs->type; funcs++)
 112     if (!strcmp(funcs->type, progt))
 113       break;
 114
 115   if (funcs->type == NULL) {
 116     funcs = &ex_types[0];
 117     warn("Execution type %s is not supported -- using %s\n",
 118       progt, funcs->type);
 119   }
 120   return funcs;
 121 }
 122
 123 int
 124 main(int ac, char **av) {
 125   int c, i, mntsize;
 126   char **command;
 127   struct procfs_status pfs;
 128   struct ex_types *funcs;
 129   struct statfs *mntbuf;
 130   int in_exec = 0;
 131   char *fname = NULL;
 132   int sigexit = 0;
 133   struct trussinfo *trussinfo;
 134
 135   /* Initialize the trussinfo struct */
 136   trussinfo = (struct trussinfo *)malloc(sizeof(struct trussinfo));
 137   if (trussinfo == NULL)
 138           errx(1, "malloc() failed");
 139   bzero(trussinfo, sizeof(struct trussinfo));
 140   trussinfo->outfile = stderr;
 141
 142   /* Check where procfs is mounted if it is mounted */
 143   if ((mntsize = getmntinfo(&mntbuf, MNT_NOWAIT)) == 0)
 144           err(1, "getmntinfo");
 145   for (i = 0; i < mntsize; i++) {
 146           if (strcasecmp(mntbuf[i].f_mntfromname, "procfs") == 0) {
 147                   strlcpy(procfs_path, mntbuf[i].f_mntonname, sizeof(procfs_path));
 148                   have_procfs = 1;
 149                   break;
 150           }
 151   }
 152   if (!have_procfs) {
 153           errno = 2;
 154           err(1, "You must have a mounted procfs to use truss");
 155   }
 156
 157   while ((c = getopt(ac, av, "p:o:S")) != -1) {
 158     switch (c) {
 159     case 'p':   /* specified pid */
 160       trussinfo->pid = atoi(optarg);
 161       if (trussinfo->pid == getpid()) {
 162               /* make sure truss doesn't trace itself */
 163               fprintf(stderr, "truss: attempt to self trace: %d\n", trussinfo->pid);
 164               exit(2);
 165       }
 166       break;
 167     case 'o':   /* Specified output file */
 168       fname = optarg;
 169       break;
 170     case 'S':   /* Don't trace signals */
 171       trussinfo->flags |= NOSIGS;
 172       break;
 173     default:
 174       usage();
 175     }
 176   }
 177
 178   ac -= optind; av += optind;
 179   if ((trussinfo->pid == 0 && ac == 0) || (trussinfo->pid != 0 && ac != 0))
 180     usage();
 181
 182   if (fname != NULL) { /* Use output file */
 183     if ((trussinfo->outfile = fopen(fname, "w")) == NULL)
 184       errx(1, "cannot open %s", fname);
 185   }
 186
 187   /*
 188    * If truss starts the process itself, it will ignore some signals --
 189    * they should be passed off to the process, which may or may not
 190    * exit.  If, however, we are examining an already-running process,
 191    * then we restore the event mask on these same signals.
 192    */
 193
 194   if (trussinfo->pid == 0) {    /* Start a command ourselves */
 195     command = av;
 196     trussinfo->pid = setup_and_wait(command);
 197     signal(SIGINT, SIG_IGN);
 198     signal(SIGTERM, SIG_IGN);
 199     signal(SIGQUIT, SIG_IGN);
 200   } else {
 201     signal(SIGINT, restore_proc);
 202     signal(SIGTERM, restore_proc);
 203     signal(SIGQUIT, restore_proc);
 204   }
 205
 206
 207   /*
 208    * At this point, if we started the process, it is stopped waiting to
 209    * be woken up, either in exit() or in execve().
 210    */
 211
 212   Procfd = start_tracing(
 213       trussinfo->pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
 214                      ((trussinfo->flags & NOSIGS) ? 0 : S_SIG));
 215   if (Procfd == -1)
 216     return 0;
 217
 218   pfs.why = 0;
 219
 220   funcs = set_etype(trussinfo);
 221   /*
 222    * At this point, it's a simple loop, waiting for the process to
 223    * stop, finding out why, printing out why, and then continuing it.
 224    * All of the grunt work is done in the support routines.
 225    */
 226
 227   do {
 228     int val = 0;
 229
 230     if (ioctl(Procfd, PIOCWAIT, &pfs) == -1)
 231       warn("PIOCWAIT top of loop");
 232     else {
 233       switch(i = pfs.why) {
 234       case S_SCE:
 235         funcs->enter_syscall(trussinfo, pfs.val);
 236         break;
 237       case S_SCX:
 238         /*
 239          * This is so we don't get two messages for an exec -- one
 240          * for the S_EXEC, and one for the syscall exit.  It also,
 241          * conveniently, ensures that the first message printed out
 242          * isn't the return-from-syscall used to create the process.
 243          */
 244
 245         if (in_exec) {
 246           in_exec = 0;
 247           break;
 248         }
 249         funcs->exit_syscall(trussinfo, pfs.val);
 250         break;
 251       case S_SIG:
 252         fprintf(trussinfo->outfile, "SIGNAL %lu\n", pfs.val);
 253         sigexit = pfs.val;
 254         break;
 255       case S_EXIT:
 256         fprintf (trussinfo->outfile, "process exit, rval = %lu\n", pfs.val);
 257         break;
 258       case S_EXEC:
 259         funcs = set_etype(trussinfo);
 260         in_exec = 1;
 261         break;
 262       default:
 263         fprintf (trussinfo->outfile, "Process stopped because of:  %d\n", i);
 264         break;
 265       }
 266     }
 267     if (ioctl(Procfd, PIOCCONT, val) == -1) {
 268       if (kill(trussinfo->pid, 0) == -1 && errno == ESRCH)
 269         break;
 270       else
 271         warn("PIOCCONT");
 272     }
 273   } while (pfs.why != S_EXIT);
 274   fflush(trussinfo->outfile);
 275   if (sigexit) {
 276     if (sigexit == SIGQUIT)
 277       exit(sigexit);
 278     (void) signal(sigexit, SIG_DFL);
 279     (void) kill(getpid(), sigexit);
 280   }
 281   return 0;
 282 }