3 * Run a command with a timeout.
5 * (c) 2011 Mark Wooding
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the Toys utilties collection.
12 * Toys is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * Toys is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with Toys; if not, write to the Free Software Foundation,
24 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27 /*----- Basic strategy ----------------------------------------------------*
29 * There's an obvious and simple way to make a process stop after a certain
30 * amount of time: set an alarm. Alarms are inherited, so this will take
31 * down the whole subprocess tree. Unfortunately, processes use alarms for
32 * all sorts of things. And this relies on the process not fiddling with its
35 * The other possibility is to have a separate process which kills our target
36 * program when the time's up. In order to do this effectively, we need to
37 * trap the whole thing in a process group. Then we need to wait until the
38 * time is up or the process finished. We'll assume that the top-level
39 * process finishing is sufficient indication that we don't need to hang on
42 * This isn't perfect. It won't catch stragglers if the target process
43 * creates its own sub-process groups -- so, in particular, nested timeouts
44 * won't behave in an obvious way. And, possibly most annoyingly, it
45 * interferes with the way terminal I/O works. I'm sorry: you can't have
49 /*----- Header files ------------------------------------------------------*/
58 #include <sys/types.h>
62 #include <sys/select.h>
65 #include <mLib/fdflags.h>
66 #include <mLib/macros.h>
67 #include <mLib/mdwopt.h>
68 #include <mLib/quis.h>
69 #include <mLib/report.h>
74 /*----- Static variables --------------------------------------------------*/
85 /*----- Argument conversion functions -------------------------------------*/
87 /* --- @namesig@ --- *
89 * Arguments: @const char *p@ = pointer to string
91 * Returns: Signal number, or @-1@ for no match.
93 * Use: Converts a signal name into its number.
101 int cmp_namesig(const void *k, const void *v)
102 { const struct namesig *ns = v; return (strcmp(k, ns->name)); }
104 static int namesig(const char *p)
106 const static struct namesig tab[] = {
108 ;;; The signal name table is very boring to type. To make life less
109 ;;; awful, put the signal names in this list and evaluate the code to
110 ;;; get Emacs to regenerate it. We use @bsearch@ on it, so it's
111 ;;; important that it be sorted: Emacs does this for us.
113 (let ((signals '(HUP INT QUIT ILL ABRT FPE KILL SEGV PIPE ALRM TERM
114 USR1 USR2 CHLD CONT STOP TSTP TTIN TTOU BUS POLL
115 PROF SYS TRAP URG VTALRM XCPU XFSZ IOT EMT STKFLT
116 IO CLD PWR INFO LOST WINCH)))
118 (goto-char (point-min))
119 (search-forward (concat "***" "BEGIN siglist" "***"))
120 (beginning-of-line 2)
121 (delete-region (point)
123 (search-forward "***END***")
126 (dolist (sig (sort (copy-list signals) #'string<))
127 (insert (format "#ifdef SIG%s\n { \"%s\", SIG%s },\n#endif\n"
131 /***BEGIN siglist***/
199 { "STKFLT", SIGSTKFLT },
232 { "VTALRM", SIGVTALRM },
235 { "WINCH", SIGWINCH },
246 const struct namesig *ns = bsearch(p, tab, N(tab), sizeof(tab[0]),
248 if (ns) return (ns->sig);
249 else if (isdigit((unsigned char)*p)) return (atoi(p));
253 /*----- Help functions ----------------------------------------------------*/
255 static void usage(FILE *fp)
256 { pquis(fp, "Usage: $ [-s SIG] SECONDS COMMAND [ARGUMENTS ...]\n"); }
258 static void version(FILE *fp)
259 { pquis(fp, "$ (version " VERSION ")\n"); }
261 static void help(FILE *fp)
263 version(fp); fputc('\n', stdout);
266 Run COMMAND, giving it the ARGUMENTS. If it fails to complete within the\n\
267 specified number of SECONDS, kill it. Otherwise exit with the status it\n\
271 -h, --help Show this help text.\n\
272 -v, --version Show version string.\n\
273 -u, --usage Show a terse usage summary.\n\
275 -s, --signal=SIG Send signal SIG to the command.\n\
279 /*----- Timeout handling --------------------------------------------------*/
281 /* --- @timeout@ --- *
283 * The first time, we send the signal requested by the caller. Then we wait
284 * five seconds for the child to die, and send @SIGKILL@. If that still
285 * doesn't help, then we just give up. It's not like there's anything else
286 * we can do which is likely to help. And it's not like the process is going
287 * to be doing anything else in user mode ever again.
297 static void timeout(struct timeval *now, void *p)
299 struct timeout *t = p;
304 moan("timed out: killing child process");
305 kill(-t->kid, t->sig);
308 moan("child hasn't responded: killing harder");
309 kill(-t->kid, SIGKILL);
312 moan("child still undead: giving up");
316 TV_ADDL(&tv, now, 5, 0);
317 sel_addtimer(&sel, &t->t, &tv, timeout, t);
321 /*----- Signal handling ---------------------------------------------------*/
323 /* --- @sigchld@ --- *
325 * If it's our child that died, fetch its exit status and stop.
333 static void sigchld(int sig, void *p)
335 struct sigchld *s = p;
339 if ((pid = waitpid(s->kid, &rc, WNOHANG)) < 0)
340 die(254, "waitpid failed: %s", strerror(errno));
347 /* --- @sigpropagate@ --- *
349 * Propagate various signals to the child process group and then maybe act on
353 static void sigpropagate(int sig, void *p)
355 struct sigchld *s = p;
359 case SIGTSTP: raise(SIGSTOP); break;
363 #define PROPAGATE_SIGNALS(_) \
364 _(TSTP) _(CONT) _(INT) _(HUP) _(QUIT)
366 /*----- Main program ------------------------------------------------------*/
370 int main(int argc, char *const argv[])
380 #define DEFSIG(tag) sig sig_##tag;
381 PROPAGATE_SIGNALS(DEFSIG)
386 /* --- Option parsing --- */
391 static const struct option opts[] = {
392 { "help", 0, 0, 'h' },
393 { "version", 0, 0, 'v' },
394 { "usage", 0, 0, 'u' },
395 { "signal", OPTF_ARGREQ, 0, 's' },
399 int i = mdwopt(argc, argv, "+hvus:", opts, 0, 0, 0);
402 case 'h': help(stdout); exit(0);
403 case 'v': version(stdout); exit(0);
404 case 'u': usage(stdout); exit(0);
406 if ((signo = namesig(optarg)) < 0)
407 die(253, "bad signal spec `%s'", optarg);
409 default: f |= F_BOGUS; break;
412 argc -= optind; argv += optind;
413 if ((f & F_BOGUS) || argc < 2) { usage(stderr); exit(253); }
416 while (isspace((unsigned char)*p)) p++;
417 t = strtod(argv[0], &p);
418 while (isspace((unsigned char)*p)) p++;
419 if (*p) die(253, "bad time value `%s'", argv[0]);
421 /* --- Get things set up --- */
426 /* --- Set up signal handling --- *
428 * Doing anything with asynchronous signals is a mug's game, so we bring
429 * them in-band. Do this before starting the child process, because
430 * otherwise we might miss an immediate @SIGCHLD@.
435 sig_add(&sig_CHLD, SIGCHLD, sigchld, &sc);
436 #define ADDSIG(tag) sig_add(&sig_##tag, SIG##tag, sigpropagate, &sc);
437 PROPAGATE_SIGNALS(ADDSIG)
440 /* --- Now start the child process --- */
442 if ((kid = fork()) < 0) die(2, "fork failed: %s", strerror(errno));
445 execvp(argv[1], argv + 1);
446 die(252, "exec(%s) failed: %s", argv[1], strerror(errno));
450 /* --- Set up the timer --- */
455 gettimeofday(&tv, 0);
456 TV_ADDL(&tv, &tv, (time_t)t, ((long)(t * 1000000))%1000000);
457 sel_addtimer(&sel, &to.t, &tv, timeout, &to);
459 /* --- Main @select@ loop */
461 while (state == ST_WAIT) {
462 if (sel_select(&sel)) {
463 if (errno == EINTR) continue;
464 die(254, "select failed: %s", strerror(errno));
468 /* --- Check and translate the exit code --- */
474 if (WIFEXITED(sc.rc))
475 exit(WEXITSTATUS(sc.rc));
476 else if (WIFSIGNALED(sc.rc))
477 exit(128 | WTERMSIG(sc.rc));
481 moan("FATAL: unexpected state %d", state);
486 /*----- That's all, folks -------------------------------------------------*/