main.c revision 38897 
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 1.10 1998/08/24 10:17:20 cracauer 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
81/*
82 * WARNING! "FreeBSD a.out" must be first, or set_etype will not
83 * work correctly.
84 */
85struct ex_types {
86  char *type;
87  void (*enter_syscall)(int, int);
88  void (*exit_syscall)(int, int);
89} ex_types[] = {
90  { "FreeBSD a.out", i386_syscall_entry, i386_syscall_exit },
91  { "FreeBSD ELF", i386_syscall_entry, i386_syscall_exit },
92  { "Linux ELF", i386_linux_syscall_entry, i386_linux_syscall_exit },
93  { 0, 0, 0 },
94};
95
96/*
97 * Set the execution type.  This is called after every exec, and when
98 * a process is first monitored.  The procfs pseudo-file "etype" has
99 * the execution module type -- see /proc/curproc/etype for an example.
100 */
101
102static struct ex_types *
103set_etype() {
104  struct ex_types *funcs;
105  char etype[24];
106  char progtype[32];
107  int fd;
108
109  sprintf(etype, "/proc/%d/etype", pid);
110  if ((fd = open(etype, O_RDONLY)) == -1) {
111    strcpy(progtype, "FreeBSD a.out");
112  } else {
113    int len = read(fd, progtype, sizeof(progtype));
114    progtype[len-1] = '\0';
115    close(fd);
116  }
117
118  for (funcs = ex_types; funcs->type; funcs++)
119    if (!strcmp(funcs->type, progtype))
120      break;
121
122  if (funcs == NULL) {
123    warn("Execution type %s is not supported -- using FreeBSD a.out\n",
124      progtype);
125    funcs = &ex_types[0];
126  }
127  return funcs;
128}
129
130int
131main(int ac, char **av) {
132  int c;
133  int i;
134  char **command;
135  struct procfs_status pfs;
136  struct ex_types *funcs;
137  int in_exec = 0;
138  char *fname = NULL;
139  int sigexit = 0;
140
141  while ((c = getopt(ac, av, "p:o:S")) != -1) {
142    switch (c) {
143    case 'p':	/* specified pid */
144      pid = atoi(optarg);
145      break;
146    case 'o':	/* Specified output file */
147      fname = optarg;
148      break;
149    case 'S':	/* Don't trace signals */
150      nosigs = 1;
151      break;
152    default:
153      usage();
154    }
155  }
156
157  ac -= optind; av += optind;
158  if ((pid == 0 && ac == 0) || (pid != 0 && ac != 0))
159    usage();
160
161  if (fname != NULL) { /* Use output file */
162    if ((outfile = fopen(fname, "w")) == NULL)
163      errx(1, "cannot open %s", fname);
164  }
165
166  /*
167   * If truss starts the process itself, it will ignore some signals --
168   * they should be passed off to the process, which may or may not
169   * exit.  If, however, we are examining an already-running process,
170   * then we restore the event mask on these same signals.
171   */
172
173  if (pid == 0) {	/* Start a command ourselves */
174    command = av;
175    pid = setup_and_wait(command);
176    signal(SIGINT, SIG_IGN);
177    signal(SIGTERM, SIG_IGN);
178    signal(SIGQUIT, SIG_IGN);
179  } else {
180    extern void restore_proc(int);
181    signal(SIGINT, restore_proc);
182    signal(SIGTERM, restore_proc);
183    signal(SIGQUIT, restore_proc);
184  }
185
186
187  /*
188   * At this point, if we started the process, it is stopped waiting to
189   * be woken up, either in exit() or in execve().
190   */
191
192  Procfd = start_tracing(pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
193		     (nosigs ? 0 : S_SIG));
194  pfs.why = 0;
195
196  funcs = set_etype();
197  /*
198   * At this point, it's a simple loop, waiting for the process to
199   * stop, finding out why, printing out why, and then continuing it.
200   * All of the grunt work is done in the support routines.
201   */
202
203  do {
204    int val = 0;
205
206    if (ioctl(Procfd, PIOCWAIT, &pfs) == -1)
207      warn("PIOCWAIT top of loop");
208    else {
209      switch(i = pfs.why) {
210      case S_SCE:
211	funcs->enter_syscall(pid, pfs.val);
212	break;
213      case S_SCX:
214	/*
215	 * This is so we don't get two messages for an exec -- one
216	 * for the S_EXEC, and one for the syscall exit.  It also,
217	 * conveniently, ensures that the first message printed out
218	 * isn't the return-from-syscall used to create the process.
219	 */
220
221	if (in_exec) {
222	  in_exec = 0;
223	  break;
224	}
225	funcs->exit_syscall(pid, pfs.val);
226	break;
227      case S_SIG:
228	fprintf(outfile, "SIGNAL %lu\n", pfs.val);
229	sigexit = pfs.val;
230	break;
231      case S_EXIT:
232	fprintf (outfile, "process exit, rval = %lu\n", pfs.val);
233	break;
234      case S_EXEC:
235	funcs = set_etype();
236	in_exec = 1;
237	break;
238      default:
239	fprintf (outfile, "Process stopped because of:  %d\n", i);
240	break;
241      }
242    }
243    if (ioctl(Procfd, PIOCCONT, val) == -1)
244      warn("PIOCCONT");
245  } while (pfs.why != S_EXIT);
246  if (sigexit) {
247    if (sigexit == SIGQUIT)
248      exit(sigexit);
249    (void) signal(sigexit, SIG_DFL);
250    (void) kill(getpid(), sigexit);
251  }
252  return 0;
253}
254