+static int get_boot_id_for_machine(const char *machine, sd_id128_t *boot_id) {
+ _cleanup_close_pipe_ int pair[2] = { -1, -1 };
+ _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, rootfd = -1;
+ pid_t pid, child;
+ siginfo_t si;
+ char buf[37];
+ ssize_t k;
+ int r;
+
+ assert(machine);
+ assert(boot_id);
+
+ if (!filename_is_safe(machine))
+ return -EINVAL;
+
+ r = container_get_leader(machine, &pid);
+ if (r < 0)
+ return r;
+
+ r = namespace_open(pid, &pidnsfd, &mntnsfd, &rootfd);
+ if (r < 0)
+ return r;
+
+ if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
+ return -errno;
+
+ child = fork();
+ if (child < 0)
+ return -errno;
+
+ if (child == 0) {
+ int fd;
+
+ close_nointr_nofail(pair[0]);
+ pair[0] = -1;
+
+ r = namespace_enter(pidnsfd, mntnsfd, rootfd);
+ if (r < 0)
+ _exit(EXIT_FAILURE);
+
+ fd = open("/proc/sys/kernel/random/boot_id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0)
+ _exit(EXIT_FAILURE);
+
+ k = loop_read(fd, buf, 36, false);
+ close_nointr_nofail(fd);
+ if (k != 36)
+ _exit(EXIT_FAILURE);
+
+ k = send(pair[1], buf, 36, MSG_NOSIGNAL);
+ if (k != 36)
+ _exit(EXIT_FAILURE);
+
+ _exit(EXIT_SUCCESS);
+ }
+
+ close_nointr_nofail(pair[1]);
+ pair[1] = -1;
+
+ r = wait_for_terminate(child, &si);
+ if (r < 0 || si.si_code != CLD_EXITED || si.si_status != EXIT_SUCCESS)
+ return r < 0 ? r : -EIO;
+
+ k = recv(pair[0], buf, 36, 0);
+ if (k != 36)
+ return -EIO;
+
+ buf[36] = 0;
+ r = sd_id128_from_string(buf, boot_id);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int add_match_this_boot(sd_journal *j, const char *machine) {
+ char match[9+32+1] = "_BOOT_ID=";
+ sd_id128_t boot_id;
+ int r;
+
+ assert(j);
+
+ if (machine) {
+ r = get_boot_id_for_machine(machine, &boot_id);
+ if (r < 0) {
+ log_error("Failed to get boot id of container %s: %s", machine, strerror(-r));
+ return r;
+ }
+ } else {
+ r = sd_id128_get_boot(&boot_id);
+ if (r < 0) {
+ log_error("Failed to get boot id: %s", strerror(-r));
+ return r;
+ }
+ }
+
+ sd_id128_to_string(boot_id, match + 9);
+ r = sd_journal_add_match(j, match, strlen(match));
+ if (r < 0) {
+ log_error("Failed to add match: %s", strerror(-r));
+ return r;
+ }
+
+ r = sd_journal_add_conjunction(j);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int show_journal_by_unit(
+ FILE *f,
+ const char *unit,
+ OutputMode mode,
+ unsigned n_columns,
+ usec_t not_before,
+ unsigned how_many,
+ uid_t uid,
+ OutputFlags flags,
+ bool system,
+ bool *ellipsized) {
+
+ _cleanup_journal_close_ sd_journal*j = NULL;
+ int r;
+ int jflags = SD_JOURNAL_LOCAL_ONLY | system * SD_JOURNAL_SYSTEM;
+
+ assert(mode >= 0);
+ assert(mode < _OUTPUT_MODE_MAX);
+ assert(unit);
+
+ if (how_many <= 0)
+ return 0;
+
+ r = sd_journal_open(&j, jflags);
+ if (r < 0)
+ return r;
+
+ r = add_match_this_boot(j, NULL);
+ if (r < 0)
+ return r;
+
+ if (system)
+ r = add_matches_for_unit(j, unit);
+ else
+ r = add_matches_for_user_unit(j, unit, uid);
+ if (r < 0)
+ return r;
+
+ if (_unlikely_(log_get_max_level() >= LOG_PRI(LOG_DEBUG))) {
+ _cleanup_free_ char *filter;
+
+ filter = journal_make_match_string(j);
+ log_debug("Journal filter: %s", filter);
+ }
+
+ return show_journal(f, j, mode, n_columns, not_before, how_many, flags, ellipsized);
+}
+