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  * $DragonFly: src/usr.bin/truss/main.c,v 1.5 2005/05/28 00:22:04 swildner Exp $
  33  */
  34
  35 /*
  36  * The main module for truss.  Suprisingly simple, but, then, the other
  37  * files handle the bulk of the work.  And, of course, the kernel has to
  38  * do a lot of the work :).
  39  */
  40
  41 #include <sys/param.h>
  42 #include <sys/ioctl.h>
  43 #include <sys/pioctl.h>
  44 #include <sys/ucred.h>
  45 #include <sys/mount.h>
  46
  47 #include <err.h>
  48 #include <errno.h>
  49 #include <fcntl.h>
  50 #include <signal.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <unistd.h>
  55
  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 pid = 0;
  64 int nosigs = 0;
  65 FILE *outfile;
  66 int Procfd;
  67
  68 static inline void
  69 usage(void)
  70 {
  71   fprintf(stderr, "%s\n%s\n",
  72         "usage: truss [-S] [-o file] -p pid",
  73         "       truss [-S] [-o file] command [args]");
  74   exit(1);
  75 }
  76
  77 /*
  78  * WARNING! "FreeBSD a.out" must be first, or set_etype will not
  79  * work correctly.
  80  */
  81 struct ex_types {
  82   const char *type;
  83   void (*enter_syscall)(int, int);
  84   void (*exit_syscall)(int, int);
  85 } ex_types[] = {
  86 #ifdef __i386__
  87   { "FreeBSD a.out", i386_syscall_entry, i386_syscall_exit },
  88   { "FreeBSD ELF", i386_syscall_entry, i386_syscall_exit },
  89   { "Linux ELF", i386_linux_syscall_entry, i386_linux_syscall_exit },
  90 #endif
  91   { 0, 0, 0 },
  92 };
  93
  94 /*
  95  * Set the execution type.  This is called after every exec, and when
  96  * a process is first monitored.  The procfs pseudo-file "etype" has
  97  * the execution module type -- see /proc/curproc/etype for an example.
  98  */
  99
 100 static struct ex_types *
 101 set_etype(void) {
 102   struct ex_types *funcs;
 103   char *etype;
 104   char progt[32];
 105   int fd;
 106
 107   asprintf(&etype, "%s/%d/etype", procfs_path, pid);
 108   if (etype == NULL)
 109     err(1, "Out of memory");
 110   if ((fd = open(etype, O_RDONLY)) == -1) {
 111     strcpy(progt, "FreeBSD a.out");
 112   } else {
 113     int len = read(fd, progt, sizeof(progt));
 114     progt[len-1] = '\0';
 115     close(fd);
 116   }
 117   free(etype);
 118
 119   for (funcs = ex_types; funcs->type; funcs++)
 120     if (!strcmp(funcs->type, progt))
 121       break;
 122
 123   if (funcs->type == NULL) {
 124     funcs = &ex_types[0];
 125     warn("Execution type %s is not supported -- using %s\n",
 126       progt, funcs->type);
 127   }
 128   return funcs;
 129 }
 130
 131 int
 132 main(int ac, char **av) {
 133   int c, i, mntsize;
 134   char **command;
 135   struct procfs_status pfs;
 136   struct ex_types *funcs;
 137   struct statfs *mntbuf;
 138   int in_exec = 0;
 139   char *fname = NULL;
 140   int sigexit = 0;
 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   outfile = stderr;
 158   while ((c = getopt(ac, av, "p:o:S")) != -1) {
 159     switch (c) {
 160     case 'p':   /* specified pid */
 161       pid = atoi(optarg);
 162       if (pid == getpid()) {
 163               /* make sure truss doesn't trace itself */
 164               fprintf(stderr, "truss: attempt to self trace: %d\n", pid);
 165               exit(2);
 166       }
 167       break;
 168     case 'o':   /* Specified output file */
 169       fname = optarg;
 170       break;
 171     case 'S':   /* Don't trace signals */
 172       nosigs = 1;
 173       break;
 174     default:
 175       usage();
 176     }
 177   }
 178
 179   ac -= optind; av += optind;
 180   if ((pid == 0 && ac == 0) || (pid != 0 && ac != 0))
 181     usage();
 182
 183   if (fname != NULL) { /* Use output file */
 184     if ((outfile = fopen(fname, "w")) == NULL)
 185       errx(1, "cannot open %s", fname);
 186   }
 187
 188   /*
 189    * If truss starts the process itself, it will ignore some signals --
 190    * they should be passed off to the process, which may or may not
 191    * exit.  If, however, we are examining an already-running process,
 192    * then we restore the event mask on these same signals.
 193    */
 194
 195   if (pid == 0) {       /* Start a command ourselves */
 196     command = av;
 197     pid = setup_and_wait(command);
 198     signal(SIGINT, SIG_IGN);
 199     signal(SIGTERM, SIG_IGN);
 200     signal(SIGQUIT, SIG_IGN);
 201   } else {
 202     signal(SIGINT, restore_proc);
 203     signal(SIGTERM, restore_proc);
 204     signal(SIGQUIT, restore_proc);
 205   }
 206
 207
 208   /*
 209    * At this point, if we started the process, it is stopped waiting to
 210    * be woken up, either in exit() or in execve().
 211    */
 212
 213   Procfd = start_tracing(pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
 214                      (nosigs ? 0 : S_SIG));
 215   if (Procfd == -1)
 216     return 0;
 217
 218   pfs.why = 0;
 219
 220   funcs = set_etype();
 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(pid, 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(pid, pfs.val);
 250         break;
 251       case S_SIG:
 252         fprintf(outfile, "SIGNAL %lu\n", pfs.val);
 253         sigexit = pfs.val;
 254         break;
 255       case S_EXIT:
 256         fprintf (outfile, "process exit, rval = %lu\n", pfs.val);
 257         break;
 258       case S_EXEC:
 259         funcs = set_etype();
 260         in_exec = 1;
 261         break;
 262       default:
 263         fprintf (outfile, "Process stopped because of:  %d\n", i);
 264         break;
 265       }
 266     }
 267     if (ioctl(Procfd, PIOCCONT, val) == -1) {
 268       if (kill(pid, 0) == -1 && errno == ESRCH)
 269         break;
 270       else
 271         warn("PIOCCONT");
 272     }
 273   } while (pfs.why != S_EXIT);
 274   fflush(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 }