main.c revision 50477 
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  "$FreeBSD: head/usr.bin/truss/main.c 50477 1999-08-28 01:08:13Z peter $";
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);
56#ifdef __alpha__
57extern void alpha_syscall_entry(int, int);
58extern void alpha_syscall_exit(int, int);
59#endif
60#ifdef __i386__
61extern void i386_syscall_entry(int, int);
62extern void i386_syscall_exit(int, int);
63extern void i386_linux_syscall_entry(int, int);
64extern void i386_linux_syscall_exit(int, int);
65#endif
66
67/*
68 * These should really be parameterized -- I don't like having globals,
69 * but this is the easiest way, right now, to deal with them.
70 */
71
72int pid = 0;
73int nosigs = 0;
74FILE *outfile = stderr;
75int Procfd;
76char progtype[50];	/* OS and type of executable */
77
78static inline void
79usage(void)
80{
81  fprintf(stderr, "%s\n%s\n",
82	"usage: truss [-S] [-o file] -p pid",
83	"       truss [-S] [-o file] command [args]");
84  exit(1);
85}
86
87/*
88 * WARNING! "FreeBSD a.out" must be first, or set_etype will not
89 * work correctly.
90 */
91struct ex_types {
92  char *type;
93  void (*enter_syscall)(int, int);
94  void (*exit_syscall)(int, int);
95} ex_types[] = {
96#ifdef __alpha__
97  { "FreeBSD ELF", alpha_syscall_entry, alpha_syscall_exit },
98#endif
99#ifdef __i386__
100  { "FreeBSD a.out", i386_syscall_entry, i386_syscall_exit },
101  { "FreeBSD ELF", i386_syscall_entry, i386_syscall_exit },
102  { "Linux ELF", i386_linux_syscall_entry, i386_linux_syscall_exit },
103#endif
104  { 0, 0, 0 },
105};
106
107/*
108 * Set the execution type.  This is called after every exec, and when
109 * a process is first monitored.  The procfs pseudo-file "etype" has
110 * the execution module type -- see /proc/curproc/etype for an example.
111 */
112
113static struct ex_types *
114set_etype() {
115  struct ex_types *funcs;
116  char etype[24];
117  char progtype[32];
118  int fd;
119
120  sprintf(etype, "/proc/%d/etype", pid);
121  if ((fd = open(etype, O_RDONLY)) == -1) {
122    strcpy(progtype, "FreeBSD a.out");
123  } else {
124    int len = read(fd, progtype, sizeof(progtype));
125    progtype[len-1] = '\0';
126    close(fd);
127  }
128
129  for (funcs = ex_types; funcs->type; funcs++)
130    if (!strcmp(funcs->type, progtype))
131      break;
132
133  if (funcs == NULL) {
134    warn("Execution type %s is not supported -- using FreeBSD a.out\n",
135      progtype);
136    funcs = &ex_types[0];
137  }
138  return funcs;
139}
140
141int
142main(int ac, char **av) {
143  int c;
144  int i;
145  char **command;
146  struct procfs_status pfs;
147  struct ex_types *funcs;
148  int in_exec = 0;
149  char *fname = NULL;
150  int sigexit = 0;
151
152  while ((c = getopt(ac, av, "p:o:S")) != -1) {
153    switch (c) {
154    case 'p':	/* specified pid */
155      pid = atoi(optarg);
156      break;
157    case 'o':	/* Specified output file */
158      fname = optarg;
159      break;
160    case 'S':	/* Don't trace signals */
161      nosigs = 1;
162      break;
163    default:
164      usage();
165    }
166  }
167
168  ac -= optind; av += optind;
169  if ((pid == 0 && ac == 0) || (pid != 0 && ac != 0))
170    usage();
171
172  if (fname != NULL) { /* Use output file */
173    if ((outfile = fopen(fname, "w")) == NULL)
174      errx(1, "cannot open %s", fname);
175  }
176
177  /*
178   * If truss starts the process itself, it will ignore some signals --
179   * they should be passed off to the process, which may or may not
180   * exit.  If, however, we are examining an already-running process,
181   * then we restore the event mask on these same signals.
182   */
183
184  if (pid == 0) {	/* Start a command ourselves */
185    command = av;
186    pid = setup_and_wait(command);
187    signal(SIGINT, SIG_IGN);
188    signal(SIGTERM, SIG_IGN);
189    signal(SIGQUIT, SIG_IGN);
190  } else {
191    extern void restore_proc(int);
192    signal(SIGINT, restore_proc);
193    signal(SIGTERM, restore_proc);
194    signal(SIGQUIT, restore_proc);
195  }
196
197
198  /*
199   * At this point, if we started the process, it is stopped waiting to
200   * be woken up, either in exit() or in execve().
201   */
202
203  Procfd = start_tracing(pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
204		     (nosigs ? 0 : S_SIG));
205  pfs.why = 0;
206
207  funcs = set_etype();
208  /*
209   * At this point, it's a simple loop, waiting for the process to
210   * stop, finding out why, printing out why, and then continuing it.
211   * All of the grunt work is done in the support routines.
212   */
213
214  do {
215    int val = 0;
216
217    if (ioctl(Procfd, PIOCWAIT, &pfs) == -1)
218      warn("PIOCWAIT top of loop");
219    else {
220      switch(i = pfs.why) {
221      case S_SCE:
222	funcs->enter_syscall(pid, pfs.val);
223	break;
224      case S_SCX:
225	/*
226	 * This is so we don't get two messages for an exec -- one
227	 * for the S_EXEC, and one for the syscall exit.  It also,
228	 * conveniently, ensures that the first message printed out
229	 * isn't the return-from-syscall used to create the process.
230	 */
231
232	if (in_exec) {
233	  in_exec = 0;
234	  break;
235	}
236	funcs->exit_syscall(pid, pfs.val);
237	break;
238      case S_SIG:
239	fprintf(outfile, "SIGNAL %lu\n", pfs.val);
240	sigexit = pfs.val;
241	break;
242      case S_EXIT:
243	fprintf (outfile, "process exit, rval = %lu\n", pfs.val);
244	break;
245      case S_EXEC:
246	funcs = set_etype();
247	in_exec = 1;
248	break;
249      default:
250	fprintf (outfile, "Process stopped because of:  %d\n", i);
251	break;
252      }
253    }
254    if (ioctl(Procfd, PIOCCONT, val) == -1)
255      warn("PIOCCONT");
256  } while (pfs.why != S_EXIT);
257  fflush(outfile);
258  if (sigexit) {
259    if (sigexit == SIGQUIT)
260      exit(sigexit);
261    (void) signal(sigexit, SIG_DFL);
262    (void) kill(getpid(), sigexit);
263  }
264  return 0;
265}
266