machine-id-commit: Introduce machine-id-commit binary

This binary enables to commit transient machine-id on disk if it becomes
writable.

.gitignore

@@ -90,6 +90,7 @@
 /systemd-kmsg-syslogd
 /systemd-localed
 /systemd-logind
+/systemd-machine-id-commit
 /systemd-machine-id-setup
 /systemd-machined
 /systemd-modeset

Makefile.am

@@ -385,6 +385,7 @@ rootlibexec_PROGRAMS = \
 	systemd-remount-fs \
 	systemd-reply-password \
 	systemd-fsck \
+	systemd-machine-id-commit \
 	systemd-ac-power \
 	systemd-sysctl \
 	systemd-sleep \
@@ -2215,6 +2216,17 @@ systemd_fsck_LDADD = \
 	libudev-internal.la \
 	libsystemd-shared.la
 
+# ------------------------------------------------------------------------------
+systemd_machine_id_commit_SOURCES = \
+	src/machine-id-commit/machine-id-commit.c \
+	src/core/machine-id-setup.c \
+	src/core/machine-id-setup.h
+
+systemd_machine_id_commit_LDADD = \
+	libsystemd-label.la \
+	libsystemd-internal.la \
+	libsystemd-shared.la
+
 # ------------------------------------------------------------------------------
 systemd_ac_power_SOURCES = \
 	src/ac-power/ac-power.c

src/machine-id-commit/Makefile

@@ -0,0 +1 @@
+../Makefile

src/machine-id-commit/machine-id-commit.c

@@ -0,0 +1,105 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Didier Roche
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <getopt.h>
+#include <errno.h>
+
+#include "machine-id-setup.h"
+#include "log.h"
+#include "build.h"
+
+static const char *arg_root = "";
+
+static void help(void) {
+        printf("%s [OPTIONS...]\n\n"
+               "Commit a transient /etc/machine-id on disk if writable.\n\n"
+               "  -h --help             Show this help\n"
+               "     --version          Show package version\n"
+               "     --root=ROOT        Filesystem root\n",
+               program_invocation_short_name);
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_VERSION = 0x100,
+                ARG_ROOT,
+        };
+
+        static const struct option options[] = {
+                { "help",      no_argument,       NULL, 'h'           },
+                { "version",   no_argument,       NULL, ARG_VERSION   },
+                { "root",      required_argument, NULL, ARG_ROOT      },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "hqcv", options, NULL)) >= 0)
+                switch (c) {
+
+                case 'h':
+                        help();
+                        return 0;
+
+                case ARG_VERSION:
+                        puts(PACKAGE_STRING);
+                        puts(SYSTEMD_FEATURES);
+                        return 0;
+
+                case ARG_ROOT:
+                        arg_root = optarg;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        if (optind < argc) {
+                log_error("Extraneous arguments");
+                return -EINVAL;
+        }
+
+        return 1;
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        log_set_target(LOG_TARGET_AUTO);
+        log_parse_environment();
+        log_open();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+
+        return machine_id_commit(arg_root) < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}