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 (6 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:       "[-s SIG] [-k KILL_SECS] SECS PROG ARGS"
  43//usage:#define timeout_full_usage "\n\n"
  44//usage:       "Run PROG. Send SIG to it if it is not gone in SECS seconds.\n"
  45//usage:       "Default SIG: TERM."
  46//usage:       "If it still exists in KILL_SECS seconds, send KILL.\n"
  47
  48#include "libbb.h"
  49
  50static NOINLINE int timeout_wait(int timeout, pid_t pid)
  51{
  52        /* Just sleep(HUGE_NUM); kill(parent) may kill wrong process! */
  53        while (1) {
  54                sleep1();
  55                if (--timeout <= 0)
  56                        break;
  57                if (kill(pid, 0)) {
  58                        /* process is gone */
  59                        return EXIT_SUCCESS;
  60                }
  61        }
  62        return EXIT_FAILURE;
  63}
  64
  65int timeout_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  66int timeout_main(int argc UNUSED_PARAM, char **argv)
  67{
  68        int signo;
  69        int status;
  70        int parent = 0;
  71        int timeout;
  72        int kill_timeout;
  73        pid_t pid;
  74#if !BB_MMU
  75        char *sv1, *sv2;
  76#endif
  77        const char *opt_s = "TERM";
  78        char *opt_k = NULL;
  79
  80        /* -p option is not documented, it is needed to support NOMMU. */
  81
  82        /* -t SECONDS; -p PARENT_PID */
  83        /* '+': stop at first non-option */
  84        getopt32(argv, "+s:k:" USE_FOR_NOMMU("p:+"), &opt_s, &opt_k, &parent);
  85        /*argv += optind; - no, wait for bb_daemonize_or_rexec! */
  86
  87        signo = get_signum(opt_s);
  88        if (signo < 0)
  89                bb_error_msg_and_die("unknown signal '%s'", opt_s);
  90
  91        kill_timeout = 0;
  92        if (opt_k)
  93                kill_timeout = parse_duration_str(opt_k);
  94
  95        if (!argv[optind])
  96                bb_show_usage();
  97        timeout = parse_duration_str(argv[optind++]);
  98        if (!argv[optind]) /* no PROG? */
  99                bb_show_usage();
 100
 101        /* We want to create a grandchild which will watch
 102         * and kill the grandparent. Other methods:
 103         * making parent watch child disrupts parent<->child link
 104         * (example: "tcpsvd 0.0.0.0 1234 timeout service_prog" -
 105         * it's better if service_prog is a child of tcpsvd!),
 106         * making child watch parent results in programs having
 107         * unexpected children. */
 108
 109        if (parent) /* we were re-execed, already grandchild */
 110                goto grandchild;
 111
 112#if !BB_MMU
 113        sv1 = argv[optind];
 114        sv2 = argv[optind + 1];
 115#endif
 116        pid = xvfork();
 117        if (pid == 0) {
 118                /* Child: spawn grandchild and exit */
 119                parent = getppid();
 120#if !BB_MMU
 121                argv[optind] = xasprintf("-p%u", parent);
 122                argv[optind + 1] = NULL;
 123#endif
 124                /* NB: exits with nonzero on error: */
 125                bb_daemonize_or_rexec(0, argv);
 126                /* Here we are grandchild. Sleep, then kill grandparent */
 127 grandchild:
 128                if (timeout_wait(timeout, parent) == EXIT_SUCCESS)
 129                        return EXIT_SUCCESS;
 130                kill(parent, signo);
 131
 132                if (kill_timeout > 0) {
 133                        if (timeout_wait(kill_timeout, parent) == EXIT_SUCCESS)
 134                                return EXIT_SUCCESS;
 135                        kill(parent, SIGKILL);
 136                }
 137
 138                return EXIT_SUCCESS;
 139        }
 140
 141        /* Parent */
 142        wait(&status); /* wait for child to die */
 143        /* Did intermediate [v]fork or exec fail? */
 144        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
 145                return EXIT_FAILURE;
 146        /* Ok, exec a program as requested */
 147        argv += optind;
 148#if !BB_MMU
 149        argv[0] = sv1;
 150        argv[1] = sv2;
 151#endif
 152        BB_EXECVP_or_die(argv);
 153}
 154