util/systemd.c

   1 /*
   2  * systemd socket activation support
   3  *
   4  * Copyright 2017 Red Hat, Inc. and/or its affiliates
   5  *
   6  * Authors:
   7  *  Richard W.M. Jones <rjones@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "qemu/systemd.h"
  15 #include "qemu/cutils.h"
  16 #include "qemu/error-report.h"
  17
  18 #ifndef _WIN32
  19 unsigned int check_socket_activation(void)
  20 {
  21     const char *s;
  22     unsigned long pid;
  23     unsigned long nr_fds;
  24     unsigned int i;
  25     int fd;
  26     int err;
  27
  28     s = getenv("LISTEN_PID");
  29     if (s == NULL) {
  30         return 0;
  31     }
  32     err = qemu_strtoul(s, NULL, 10, &pid);
  33     if (err) {
  34         return 0;
  35     }
  36     if (pid != getpid()) {
  37         return 0;
  38     }
  39
  40     s = getenv("LISTEN_FDS");
  41     if (s == NULL) {
  42         return 0;
  43     }
  44     err = qemu_strtoul(s, NULL, 10, &nr_fds);
  45     if (err) {
  46         return 0;
  47     }
  48     assert(nr_fds <= UINT_MAX);
  49
  50     /* So these are not passed to any child processes we might start. */
  51     unsetenv("LISTEN_FDS");
  52     unsetenv("LISTEN_PID");
  53
  54     /* So the file descriptors don't leak into child processes. */
  55     for (i = 0; i < nr_fds; ++i) {
  56         fd = FIRST_SOCKET_ACTIVATION_FD + i;
  57         if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
  58             /* If we cannot set FD_CLOEXEC then it probably means the file
  59              * descriptor is invalid, so socket activation has gone wrong
  60              * and we should exit.
  61              */
  62             error_report("Socket activation failed: "
  63                          "invalid file descriptor fd = %d: %s",
  64                          fd, g_strerror(errno));
  65             exit(EXIT_FAILURE);
  66         }
  67     }
  68
  69     return (unsigned int) nr_fds;
  70 }
  71
  72 #else /* !_WIN32 */
  73 unsigned int check_socket_activation(void)
  74 {
  75     return 0;
  76 }
  77 #endif