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 (6.5 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:       "[-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
  50 static NOINLINE int timeout_wait(duration_t timeout, pid_t pid)
  51 {
  52         /* Just sleep(HUGE_NUM); kill(parent) may kill wrong process! */
  53         while (1) {
  54 #if ENABLE_FLOAT_DURATION
  55                 if (timeout < 1)
  56                         sleep_for_duration(timeout);
  57                 else
  58 #endif
  59                         sleep1();
  60                 if (--timeout <= 0)
  61                         break;
  62                 if (kill(pid, 0)) {
  63                         /* process is gone */
  64                         return EXIT_SUCCESS;
  65                 }
  66         }
  67         return EXIT_FAILURE;
  68 }
  69
  70 int timeout_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  71 int timeout_main(int argc UNUSED_PARAM, char **argv)
  72 {
  73         int signo;
  74         int status;
  75         int parent = 0;
  76         duration_t timeout;
  77         duration_t kill_timeout;
  78         pid_t pid;
  79 #if !BB_MMU
  80         char *sv1, *sv2;
  81 #endif
  82         const char *opt_s = "TERM";
  83         char *opt_k = NULL;
  84
  85         /* -p option is not documented, it is needed to support NOMMU. */
  86
  87         /* -t SECONDS; -p PARENT_PID */
  88         /* '+': stop at first non-option */
  89         getopt32(argv, "+s:k:" USE_FOR_NOMMU("p:+"), &opt_s, &opt_k, &parent);
  90         /*argv += optind; - no, wait for bb_daemonize_or_rexec! */
  91
  92         signo = get_signum(opt_s);
  93         if (signo < 0)
  94                 bb_error_msg_and_die("unknown signal '%s'", opt_s);
  95
  96         kill_timeout = 0;
  97         if (opt_k)
  98                 kill_timeout = parse_duration_str(opt_k);
  99
 100         if (!argv[optind])
 101                 bb_show_usage();
 102         timeout = parse_duration_str(argv[optind++]);
 103         if (!argv[optind]) /* no PROG? */
 104                 bb_show_usage();
 105
 106         /* We want to create a grandchild which will watch
 107          * and kill the grandparent. Other methods:
 108          * making parent watch child disrupts parent<->child link
 109          * (example: "tcpsvd 0.0.0.0 1234 timeout service_prog" -
 110          * it's better if service_prog is a child of tcpsvd!),
 111          * making child watch parent results in programs having
 112          * unexpected children. */
 113
 114         if (parent) /* we were re-execed, already grandchild */
 115                 goto grandchild;
 116
 117 #if !BB_MMU
 118         sv1 = argv[optind];
 119         sv2 = argv[optind + 1];
 120 #endif
 121         pid = xvfork();
 122         if (pid == 0) {
 123                 /* Child: spawn grandchild and exit */
 124                 parent = getppid();
 125 #if !BB_MMU
 126                 argv[optind] = xasprintf("-p%u", parent);
 127                 argv[optind + 1] = NULL;
 128 #endif
 129                 /* NB: exits with nonzero on error: */
 130                 bb_daemonize_or_rexec(0, argv);
 131                 /* Here we are grandchild. Sleep, then kill grandparent */
 132  grandchild:
 133                 if (timeout_wait(timeout, parent) == EXIT_SUCCESS)
 134                         return EXIT_SUCCESS;
 135                 kill(parent, signo);
 136
 137                 if (kill_timeout > 0) {
 138                         if (timeout_wait(kill_timeout, parent) == EXIT_SUCCESS)
 139                                 return EXIT_SUCCESS;
 140                         kill(parent, SIGKILL);
 141                 }
 142
 143                 return EXIT_SUCCESS;
 144         }
 145
 146         /* Parent */
 147         wait(&status); /* wait for child to die */
 148         /* Did intermediate [v]fork or exec fail? */
 149         if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
 150                 return EXIT_FAILURE;
 151         /* Ok, exec a program as requested */
 152         argv += optind;
 153 #if !BB_MMU
 154         argv[0] = sv1;
 155         argv[1] = sv2;
 156 #endif
 157         BB_EXECVP_or_die(argv);
 158 }