server/socket-activation.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 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <stdarg.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 #include <fcntl.h>
  41 #include <errno.h>
  42
  43 #include "internal.h"
  44
  45 #ifndef WIN32
  46
  47 /* Handle socket activation.  This is controlled through special
  48  * environment variables inherited by nbdkit.  Returns 0 if no socket
  49  * activation.  Otherwise returns the number of FDs.  See also
  50  * virGetListenFDs in libvirt.org:src/util/virutil.c
  51  */
  52 unsigned int
  53 get_socket_activation (void)
  54 {
  55   const char *s;
  56   unsigned int pid;
  57   unsigned int nr_fds;
  58   unsigned int i;
  59   int fd;
  60   int f;
  61
  62   s = getenv ("LISTEN_PID");
  63   if (s == NULL)
  64     return 0;
  65   if (nbdkit_parse_unsigned ("LISTEN_PID", s, &pid) == -1)
  66     return 0;
  67   if (pid != getpid ()) {
  68     fprintf (stderr, "%s: %s was not for us (ignored)\n",
  69              program_name, "LISTEN_PID");
  70     return 0;
  71   }
  72
  73   s = getenv ("LISTEN_FDS");
  74   if (s == NULL)
  75     return 0;
  76   if (nbdkit_parse_unsigned ("LISTEN_FDS", s, &nr_fds) == -1)
  77     return 0;
  78
  79   /* Limit the number of fds that may be passed in to something
  80    * reasonable.
  81    */
  82   if (nr_fds == 0 || nr_fds > 16) {
  83     fprintf (stderr, "%s: socket activation: LISTEN_FDS=%s out of range\n",
  84              program_name, s);
  85     exit (EXIT_FAILURE);
  86   }
  87
  88   /* So these are not passed to any child processes we might start. */
  89   unsetenv ("LISTEN_FDS");
  90   unsetenv ("LISTEN_PID");
  91
  92   /* So the file descriptors don't leak into child processes. */
  93   for (i = 0; i < nr_fds; ++i) {
  94     fd = FIRST_SOCKET_ACTIVATION_FD + i;
  95     f = fcntl (fd, F_GETFD);
  96     if (f == -1 || fcntl (fd, F_SETFD, f | FD_CLOEXEC) == -1) {
  97       /* If we cannot set FD_CLOEXEC then it probably means the file
  98        * descriptor is invalid, so socket activation has gone wrong
  99        * and we should exit.
 100        */
 101       fprintf (stderr, "%s: socket activation: "
 102                "invalid file descriptor fd = %d: %s\n",
 103                program_name, fd, strerror (errno));
 104       exit (EXIT_FAILURE);
 105     }
 106   }
 107
 108   return nr_fds;
 109 }
 110
 111 #else /* WIN32 */
 112
 113 unsigned int
 114 get_socket_activation (void)
 115 {
 116   return 0;
 117 }
 118
 119 #endif /* WIN32 */