main.c revision 38520 
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
32#ifndef lint
33static const char rcsid[] =
34	"$Id: main.c,v 1.9 1998/07/06 21:01:47 bde Exp $";
35#endif /* not lint */
36
37/*
38 * The main module for truss.  Suprisingly simple, but, then, the other
39 * files handle the bulk of the work.  And, of course, the kernel has to
40 * do a lot of the work :).
41 */
42
43#include <err.h>
44#include <errno.h>
45#include <fcntl.h>
46#include <signal.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <unistd.h>
51#include <sys/ioctl.h>
52#include <sys/pioctl.h>
53
54extern int setup_and_wait(char **);
55extern int start_tracing(int, int);
56extern void i386_syscall_entry(int, int);
57extern void i386_syscall_exit(int, int);
58extern void i386_linux_syscall_entry(int, int);
59extern void i386_linux_syscall_exit(int, int);
60
61/*
62 * These should really be parameterized -- I don't like having globals,
63 * but this is the easiest way, right now, to deal with them.
64 */
65
66int pid = 0;
67int nosigs = 0;
68FILE *outfile = stderr;
69int Procfd;
70char progtype[50];	/* OS and type of executable */
71
72static inline void
73usage(void)
74{
75  fprintf(stderr, "%s\n%s\n",
76	"usage: truss [-S] [-o file] -p pid",
77	"       truss [-S] [-o file] command [args]");
78  exit(1);
79}
80
81struct ex_types {
82  char *type;
83  void (*enter_syscall)(int, int);
84  void (*exit_syscall)(int, int);
85} ex_types[] = {
86  { "FreeBSD a.out", i386_syscall_entry, i386_syscall_exit },
87  { "FreeBSD ELF", i386_syscall_entry, i386_syscall_exit },
88  { "Linux ELF", i386_linux_syscall_entry, i386_linux_syscall_exit },
89  { 0, 0, 0 },
90};
91
92/*
93 * Set the execution type.  This is called after every exec, and when
94 * a process is first monitored.  The procfs pseudo-file "etype" has
95 * the execution module type -- see /proc/curproc/etype for an example.
96 */
97
98static struct ex_types *
99set_etype() {
100  struct ex_types *funcs;
101  char etype[24];
102  char progtype[32];
103  int fd;
104
105  sprintf(etype, "/proc/%d/etype", pid);
106  if ((fd = open(etype, O_RDONLY)) == -1) {
107    strcpy(progtype, "FreeBSD a.out");
108  } else {
109    int len = read(fd, progtype, sizeof(progtype));
110    progtype[len-1] = '\0';
111    close(fd);
112  }
113
114  for (funcs = ex_types; funcs->type; funcs++)
115    if (!strcmp(funcs->type, progtype))
116      break;
117
118  return funcs;
119}
120
121int
122main(int ac, char **av) {
123  int c;
124  int i;
125  char **command;
126  struct procfs_status pfs;
127  struct ex_types *funcs;
128  int in_exec = 0;
129  char *fname = NULL;
130  int sigexit = 0;
131
132  while ((c = getopt(ac, av, "p:o:S")) != -1) {
133    switch (c) {
134    case 'p':	/* specified pid */
135      pid = atoi(optarg);
136      break;
137    case 'o':	/* Specified output file */
138      fname = optarg;
139      break;
140    case 'S':	/* Don't trace signals */
141      nosigs = 1;
142      break;
143    default:
144      usage();
145    }
146  }
147
148  ac -= optind; av += optind;
149  if ((pid == 0 && ac == 0) || (pid != 0 && ac != 0))
150    usage();
151
152  if (fname != NULL) { /* Use output file */
153    if ((outfile = fopen(fname, "w")) == NULL)
154      errx(1, "cannot open %s", fname);
155  }
156
157  /*
158   * If truss starts the process itself, it will ignore some signals --
159   * they should be passed off to the process, which may or may not
160   * exit.  If, however, we are examining an already-running process,
161   * then we restore the event mask on these same signals.
162   */
163
164  if (pid == 0) {	/* Start a command ourselves */
165    command = av;
166    pid = setup_and_wait(command);
167    signal(SIGINT, SIG_IGN);
168    signal(SIGTERM, SIG_IGN);
169    signal(SIGQUIT, SIG_IGN);
170  } else {
171    extern void restore_proc(int);
172    signal(SIGINT, restore_proc);
173    signal(SIGTERM, restore_proc);
174    signal(SIGQUIT, restore_proc);
175  }
176
177
178  /*
179   * At this point, if we started the process, it is stopped waiting to
180   * be woken up, either in exit() or in execve().
181   */
182
183  Procfd = start_tracing(pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
184		     (nosigs ? 0 : S_SIG));
185  pfs.why = 0;
186
187  funcs = set_etype();
188  /*
189   * At this point, it's a simple loop, waiting for the process to
190   * stop, finding out why, printing out why, and then continuing it.
191   * All of the grunt work is done in the support routines.
192   */
193
194  do {
195    int val = 0;
196
197    if (ioctl(Procfd, PIOCWAIT, &pfs) == -1)
198      warn("PIOCWAIT top of loop");
199    else {
200      switch(i = pfs.why) {
201      case S_SCE:
202	funcs->enter_syscall(pid, pfs.val);
203	break;
204      case S_SCX:
205	/*
206	 * This is so we don't get two messages for an exec -- one
207	 * for the S_EXEC, and one for the syscall exit.  It also,
208	 * conveniently, ensures that the first message printed out
209	 * isn't the return-from-syscall used to create the process.
210	 */
211
212	if (in_exec) {
213	  in_exec = 0;
214	  break;
215	}
216	funcs->exit_syscall(pid, pfs.val);
217	break;
218      case S_SIG:
219	fprintf(outfile, "SIGNAL %lu\n", pfs.val);
220	sigexit = pfs.val;
221	break;
222      case S_EXIT:
223	fprintf (outfile, "process exit, rval = %lu\n", pfs.val);
224	break;
225      case S_EXEC:
226	funcs = set_etype();
227	in_exec = 1;
228	break;
229      default:
230	fprintf (outfile, "Process stopped because of:  %d\n", i);
231	break;
232      }
233    }
234    if (ioctl(Procfd, PIOCCONT, val) == -1)
235      warn("PIOCCONT");
236  } while (pfs.why != S_EXIT);
237  if (sigexit) {
238    if (sigexit == SIGQUIT)
239      exit(sigexit);
240    (void) signal(sigexit, SIG_DFL);
241    (void) kill(getpid(), sigexit);
242  }
243  return 0;
244}
245