common/utils/exit-with-parent.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /* Implement the --exit-with-parent feature on operating systems which
  34  * support it.
  35  */
  36
  37 #include <config.h>
  38
  39 #include <stdlib.h>
  40 #include <stdbool.h>
  41 #include <signal.h>
  42
  43 #ifdef HAVE_SYS_PRCTL_H
  44 #include <sys/prctl.h>
  45 #endif
  46
  47 #ifdef HAVE_SYS_PROCCTL_H
  48 #include <sys/procctl.h>
  49 #endif
  50
  51 #if defined (HAVE_SYS_PRCTL_H) && defined (PR_SET_PDEATHSIG)
  52
  53 /* For Linux >= 2.1.57. */
  54
  55 int
  56 set_exit_with_parent (void)
  57 {
  58   return prctl (PR_SET_PDEATHSIG, SIGTERM);
  59 }
  60
  61 bool
  62 can_exit_with_parent (void)
  63 {
  64   return true;
  65 }
  66
  67 #elif defined (HAVE_SYS_PROCCTL_H) && defined (PROC_PDEATHSIG_CTL)
  68
  69 /* For FreeBSD >= 11.2 */
  70
  71 int
  72 set_exit_with_parent (void)
  73 {
  74   const int sig = SIGTERM;
  75   return procctl (P_PID, 0, PROC_PDEATHSIG_CTL, (void*) &sig);
  76 }
  77
  78 bool
  79 can_exit_with_parent (void)
  80 {
  81   return true;
  82 }
  83
  84 #elif defined (__APPLE__)
  85
  86 /* For macOS. */
  87
  88 #include <unistd.h>
  89 #include <errno.h>
  90 #include <sys/event.h>
  91 #include <pthread.h>
  92
  93 #include "nbdkit-plugin.h"
  94
  95 static void *
  96 exit_with_parent_loop (void *vp)
  97 {
  98   const pid_t ppid = getppid ();
  99   int fd;
 100   struct kevent kev, res[1];
 101   int r;
 102
 103   nbdkit_debug ("macOS: --exit-with-parent: "
 104                 "registering exit with parent for ppid %d",
 105                 (int) ppid);
 106
 107   /* Register the kevent to wait for ppid to exit. */
 108   fd = kqueue ();
 109   if (fd == -1) {
 110     nbdkit_error ("exit_with_parent_loop: kqueue: %m");
 111     return NULL;
 112   }
 113   EV_SET (&kev, ppid, EVFILT_PROC, EV_ADD|EV_ENABLE, NOTE_EXIT, 0, NULL);
 114   if (kevent (fd, &kev, 1, NULL, 0, NULL) == -1) {
 115     nbdkit_error ("exit_with_parent_loop: kevent: %m");
 116     close (fd);
 117     return NULL;
 118   }
 119
 120   /* Wait for the kevent to happen. */
 121   r = kevent (fd, 0, 0, res, 1, NULL);
 122   if (r == 1 && res[0].ident == ppid) {
 123     /* Shut down the whole process when the parent dies. */
 124     nbdkit_debug ("macOS: --exit-with-parent: "
 125                   "exit because parent process died");
 126     nbdkit_shutdown ();
 127   }
 128
 129   return NULL;
 130 }
 131
 132 int
 133 set_exit_with_parent (void)
 134 {
 135   int r;
 136   pthread_attr_t attrs;
 137   pthread_t exit_with_parent_thread;
 138
 139   /* We have to block waiting for kevent, so that requires that we
 140    * start a background thread.
 141    */
 142   pthread_attr_init (&attrs);
 143   pthread_attr_setdetachstate (&attrs, PTHREAD_CREATE_DETACHED);
 144   r = pthread_create (&exit_with_parent_thread, NULL,
 145                       exit_with_parent_loop, NULL);
 146   if (r != 0) {
 147     errno = r;
 148     return -1;
 149   }
 150
 151   return 0;
 152 }
 153
 154 bool
 155 can_exit_with_parent (void)
 156 {
 157   return true;
 158 }
 159
 160 #else /* any platform that doesn't support this function */
 161
 162 int
 163 set_exit_with_parent (void)
 164 {
 165   abort ();
 166 }
 167
 168 bool
 169 can_exit_with_parent (void)
 170 {
 171   return false;
 172 }
 173
 174 #endif