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 f;
  27     int err;
  28
  29     s = getenv("LISTEN_PID");
  30     if (s == NULL) {
  31         return 0;
  32     }
  33     err = qemu_strtoul(s, NULL, 10, &pid);
  34     if (err) {
  35         return 0;
  36     }
  37     if (pid != getpid()) {
  38         return 0;
  39     }
  40
  41     s = getenv("LISTEN_FDS");
  42     if (s == NULL) {
  43         return 0;
  44     }
  45     err = qemu_strtoul(s, NULL, 10, &nr_fds);
  46     if (err) {
  47         return 0;
  48     }
  49     assert(nr_fds <= UINT_MAX);
  50
  51     /* So these are not passed to any child processes we might start. */
  52     unsetenv("LISTEN_FDS");
  53     unsetenv("LISTEN_PID");
  54     unsetenv("LISTEN_FDNAMES");
  55
  56     /* So the file descriptors don't leak into child processes. */
  57     for (i = 0; i < nr_fds; ++i) {
  58         fd = FIRST_SOCKET_ACTIVATION_FD + i;
  59         f = fcntl(fd, F_GETFD);
  60         if (f == -1 || fcntl(fd, F_SETFD, f | FD_CLOEXEC) == -1) {
  61             /* If we cannot set FD_CLOEXEC then it probably means the file
  62              * descriptor is invalid, so socket activation has gone wrong
  63              * and we should exit.
  64              */
  65             error_report("Socket activation failed: "
  66                          "invalid file descriptor fd = %d: %s",
  67                          fd, g_strerror(errno));
  68             exit(EXIT_FAILURE);
  69         }
  70     }
  71
  72     return (unsigned int) nr_fds;
  73 }
  74
  75 #else /* !_WIN32 */
  76 unsigned int check_socket_activation(void)
  77 {
  78     return 0;
  79 }
  80 #endif