+
+int sd_notify(int unset_environment, const char *state) {
+#if defined(DISABLE_SYSTEMD) || !defined(__linux__) || !defined(SOCK_CLOEXEC)
+ return 0;
+#else
+ int fd = -1, r;
+ struct msghdr msghdr;
+ struct iovec iovec;
+ union sockaddr_union sockaddr;
+ struct ucred *ucred;
+ union {
+ struct cmsghdr cmsghdr;
+ uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
+ } control;
+ const char *e;
+
+ if (!state) {
+ r = -EINVAL;
+ goto finish;
+ }
+
+ if (!(e = getenv("NOTIFY_SOCKET")))
+ return 0;
+
+ /* Must be an abstract socket, or an absolute path */
+ if ((e[0] != '@' && e[0] != '/') || e[1] == 0) {
+ r = -EINVAL;
+ goto finish;
+ }
+
+ if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ memset(&sockaddr, 0, sizeof(sockaddr));
+ sockaddr.sa.sa_family = AF_UNIX;
+ strncpy(sockaddr.un.sun_path, e, sizeof(sockaddr.un.sun_path));
+
+ if (sockaddr.un.sun_path[0] == '@')
+ sockaddr.un.sun_path[0] = 0;
+
+ memset(&iovec, 0, sizeof(iovec));
+ iovec.iov_base = (char*) state;
+ iovec.iov_len = strlen(state);
+
+ memset(&control, 0, sizeof(control));
+ control.cmsghdr.cmsg_level = SOL_SOCKET;
+ control.cmsghdr.cmsg_type = SCM_CREDENTIALS;
+ control.cmsghdr.cmsg_len = CMSG_LEN(sizeof(struct ucred));
+
+ ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
+ ucred->pid = getpid();
+ ucred->uid = getuid();
+ ucred->gid = getgid();
+
+ memset(&msghdr, 0, sizeof(msghdr));
+ msghdr.msg_name = &sockaddr;
+ msghdr.msg_namelen = sizeof(sa_family_t) + strlen(e);
+
+ if (msghdr.msg_namelen > sizeof(struct sockaddr_un))
+ msghdr.msg_namelen = sizeof(struct sockaddr_un);
+
+ msghdr.msg_iov = &iovec;
+ msghdr.msg_iovlen = 1;
+ msghdr.msg_control = &control;
+ msghdr.msg_controllen = control.cmsghdr.cmsg_len;
+
+ if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ r = 1;
+
+finish:
+ if (unset_environment)
+ unsetenv("NOTIFY_SOCKET");
+
+ if (fd >= 0)
+ close(fd);
+
+ return r;
+#endif
+}
+
+int sd_notifyf(int unset_environment, const char *format, ...) {
+#if defined(DISABLE_SYSTEMD) || !defined(__linux__)
+ return 0;
+#else
+ va_list ap;
+ char *p = NULL;
+ int r;
+
+ va_start(ap, format);
+ r = vasprintf(&p, format, ap);
+ va_end(ap);
+
+ if (r < 0 || !p)
+ return -ENOMEM;
+
+ r = sd_notify(unset_environment, p);
+ free(p);
+
+ return r;
+#endif
+}
+
+int sd_booted(void) {
+#if defined(DISABLE_SYSTEMD) || !defined(__linux__)
+ return 0;
+#else
+
+ struct stat a, b;
+
+ /* We simply test whether the systemd cgroup hierarchy is
+ * mounted */
+
+ if (lstat("/cgroup", &a) < 0)
+ return 0;
+
+ if (lstat("/cgroup/systemd", &b) < 0)
+ return 0;
+
+ return a.st_dev != b.st_dev;
+#endif
+}