LXR busybox/coreutils/timeout.c

   1/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
   2 * COPYING NOTES
   3 *
   4 * timeout.c -- a timeout handler for shell commands
   5 *
   6 * Copyright (C) 2005-6, Roberto A. Foglietta <me@roberto.foglietta.name>
   7 *
   8 *   This program is free software; you can redistribute it and/or modify
   9 *   it under the terms of the GNU General Public License as published by
  10 *   the Free Software Foundation; version 2 of the License.
  11 *
  12 *   This program is distributed in the hope that it will be useful,
  13 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 *   GNU General Public License for more details.
  16 *
  17 *   You should have received a copy of the GNU General Public License
  18 *   along with this program; if not, write to the Free Software
  19 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  20 */
  21/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  22 * REVISION NOTES:
  23 * released 17-11-2005 by Roberto A. Foglietta
  24 * talarm   04-12-2005 by Roberto A. Foglietta
  25 * modified 05-12-2005 by Roberto A. Foglietta
  26 * sizerdct 06-12-2005 by Roberto A. Foglietta
  27 * splitszf 12-05-2006 by Roberto A. Foglietta
  28 * rewrite  14-11-2008 vda
  29 */
  30//config:config TIMEOUT
  31//config:       bool "timeout (5.5 kb)"
  32//config:       default y
  33//config:       help
  34//config:       Runs a program and watches it. If it does not terminate in
  35//config:       specified number of seconds, it is sent a signal.
  36
  37//applet:IF_TIMEOUT(APPLET(timeout, BB_DIR_USR_BIN, BB_SUID_DROP))
  38
  39//kbuild:lib-$(CONFIG_TIMEOUT) += timeout.o
  40
  41//usage:#define timeout_trivial_usage
  42//usage:       "[-t SECS] [-s SIG] PROG ARGS"
  43//usage:#define timeout_full_usage "\n\n"
  44//usage:       "Runs PROG. Sends SIG to it if it is not gone in SECS seconds.\n"
  45//usage:       "Defaults: SECS: 10, SIG: TERM."
  46
  47#include "libbb.h"
  48
  49int timeout_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  50int timeout_main(int argc UNUSED_PARAM, char **argv)
  51{
  52        int signo;
  53        int status;
  54        int parent = 0;
  55        int timeout = 10;
  56        pid_t pid;
  57#if !BB_MMU
  58        char *sv1, *sv2;
  59#endif
  60        const char *opt_s = "TERM";
  61
  62        /* -p option is not documented, it is needed to support NOMMU. */
  63
  64        /* -t SECONDS; -p PARENT_PID */
  65        /* '+': stop at first non-option */
  66        getopt32(argv, "+s:t:+" USE_FOR_NOMMU("p:+"), &opt_s, &timeout, &parent);
  67        /*argv += optind; - no, wait for bb_daemonize_or_rexec! */
  68        signo = get_signum(opt_s);
  69        if (signo < 0)
  70                bb_error_msg_and_die("unknown signal '%s'", opt_s);
  71
  72        /* We want to create a grandchild which will watch
  73         * and kill the grandparent. Other methods:
  74         * making parent watch child disrupts parent<->child link
  75         * (example: "tcpsvd 0.0.0.0 1234 timeout service_prog" -
  76         * it's better if service_prog is a child of tcpsvd!),
  77         * making child watch parent results in programs having
  78         * unexpected children. */
  79
  80        if (parent) /* we were re-execed, already grandchild */
  81                goto grandchild;
  82        if (!argv[optind]) /* no PROG? */
  83                bb_show_usage();
  84
  85#if !BB_MMU
  86        sv1 = argv[optind];
  87        sv2 = argv[optind + 1];
  88#endif
  89        pid = xvfork();
  90        if (pid == 0) {
  91                /* Child: spawn grandchild and exit */
  92                parent = getppid();
  93#if !BB_MMU
  94                argv[optind] = xasprintf("-p%u", parent);
  95                argv[optind + 1] = NULL;
  96#endif
  97                /* NB: exits with nonzero on error: */
  98                bb_daemonize_or_rexec(0, argv);
  99                /* Here we are grandchild. Sleep, then kill grandparent */
 100 grandchild:
 101                /* Just sleep(HUGE_NUM); kill(parent) may kill wrong process! */
 102                while (1) {
 103                        sleep(1);
 104                        if (--timeout <= 0)
 105                                break;
 106                        if (kill(parent, 0)) {
 107                                /* process is gone */
 108                                return EXIT_SUCCESS;
 109                        }
 110                }
 111                kill(parent, signo);
 112                return EXIT_SUCCESS;
 113        }
 114
 115        /* Parent */
 116        wait(&status); /* wait for child to die */
 117        /* Did intermediate [v]fork or exec fail? */
 118        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
 119                return EXIT_FAILURE;
 120        /* Ok, exec a program as requested */
 121        argv += optind;
 122#if !BB_MMU
 123        argv[0] = sv1;
 124        argv[1] = sv2;
 125#endif
 126        BB_EXECVP_or_die(argv);
 127}
 128