+static int setup_journal(const char *directory) {
+ sd_id128_t machine_id;
+ char _cleanup_free_ *p = NULL, *b = NULL, *q = NULL, *d = NULL;
+ char *id;
+ int r;
+
+ if (arg_link_journal == LINK_NO)
+ return 0;
+
+ p = strappend(directory, "/etc/machine-id");
+ if (!p)
+ return log_oom();
+
+ r = read_one_line_file(p, &b);
+ if (r == -ENOENT && arg_link_journal == LINK_AUTO)
+ return 0;
+ else if (r < 0) {
+ log_error("Failed to read machine ID from %s: %s", p, strerror(-r));
+ return r;
+ }
+
+ id = strstrip(b);
+ if (isempty(id) && arg_link_journal == LINK_AUTO)
+ return 0;
+
+ /* Verify validity */
+ r = sd_id128_from_string(id, &machine_id);
+ if (r < 0) {
+ log_error("Failed to parse machine ID from %s: %s", p, strerror(-r));
+ return r;
+ }
+
+ free(p);
+ p = strappend("/var/log/journal/", id);
+ q = strjoin(directory, "/var/log/journal/", id, NULL);
+ if (!p || !q)
+ return log_oom();
+
+ if (path_is_mount_point(p, false) > 0) {
+ if (arg_link_journal != LINK_AUTO) {
+ log_error("%s: already a mount point, refusing to use for journal", p);
+ return -EEXIST;
+ }
+
+ return 0;
+ }
+
+ if (path_is_mount_point(q, false) > 0) {
+ if (arg_link_journal != LINK_AUTO) {
+ log_error("%s: already a mount point, refusing to use for journal", q);
+ return -EEXIST;
+ }
+
+ return 0;
+ }
+
+ r = readlink_and_make_absolute(p, &d);
+ if (r >= 0) {
+ if ((arg_link_journal == LINK_GUEST ||
+ arg_link_journal == LINK_AUTO) &&
+ path_equal(d, q)) {
+
+ r = mkdir_p(q, 0755);
+ if (r < 0)
+ log_warning("failed to create directory %s: %m", q);
+ return 0;
+ }
+
+ if (unlink(p) < 0) {
+ log_error("Failed to remove symlink %s: %m", p);
+ return -errno;
+ }
+ } else if (r == -EINVAL) {
+
+ if (arg_link_journal == LINK_GUEST &&
+ rmdir(p) < 0) {
+
+ if (errno == ENOTDIR) {
+ log_error("%s already exists and is neither a symlink nor a directory", p);
+ return r;
+ } else {
+ log_error("Failed to remove %s: %m", p);
+ return -errno;
+ }
+ }
+ } else if (r != -ENOENT) {
+ log_error("readlink(%s) failed: %m", p);
+ return r;
+ }
+
+ if (arg_link_journal == LINK_GUEST) {
+
+ if (symlink(q, p) < 0) {
+ log_error("Failed to symlink %s to %s: %m", q, p);
+ return -errno;
+ }
+
+ r = mkdir_p(q, 0755);
+ if (r < 0)
+ log_warning("failed to create directory %s: %m", q);
+ return 0;
+ }
+
+ if (arg_link_journal == LINK_HOST) {
+ r = mkdir_p(p, 0755);
+ if (r < 0) {
+ log_error("Failed to create %s: %m", p);
+ return r;
+ }
+
+ } else if (access(p, F_OK) < 0)
+ return 0;
+
+ if (dir_is_empty(q) == 0) {
+ log_error("%s not empty.", q);
+ return -ENOTEMPTY;
+ }
+
+ r = mkdir_p(q, 0755);
+ if (r < 0) {
+ log_error("Failed to create %s: %m", q);
+ return r;
+ }
+
+ if (mount(p, q, "bind", MS_BIND, NULL) < 0) {
+ log_error("Failed to bind mount journal from host into guest: %m");
+ return -errno;
+ }
+
+ return 0;
+}
+