systemd-id128: a new tool to print machine/boot/invocation/app-specific ids

The raison d'etre for this program is printing machine-app-specific IDs. We
provide a library function for that, but not a convenient API. We can hardly
ask people to quickly hack their own C programs or call libsystemd through CFFI
in python or another scripting language if they just want to print an ID.

Verb 'new' was already available as 'journalctl --new-id128', but this makes
it more discoverable.

v2:
- rename binary to systemd-id128
- make --app-specific= into a switch that applies to boot-id and machine-id

1 files changed, 167 insertions, 0 deletions

diff --git a/src/id128/id128.c b/src/id128/id128.c
new file mode 100644
index 0000000000..a6391313be
--- /dev/null
+++ b/src/id128/id128.c
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <getopt.h>
+#include <stdio.h>
+
+#include "alloc-util.h"
+#include "id128-print.h"
+#include "terminal-util.h"
+#include "util.h"
+#include "verbs.h"
+
+static bool arg_pretty = false;
+static sd_id128_t arg_app = {};
+
+static int verb_new(int argc, char **argv, void *userdata) {
+        return id128_print_new(arg_pretty);
+}
+
+static int verb_machine_id(int argc, char **argv, void *userdata) {
+        sd_id128_t id;
+        int r;
+
+        if (sd_id128_is_null(arg_app))
+                r = sd_id128_get_machine(&id);
+        else
+                r = sd_id128_get_machine_app_specific(arg_app, &id);
+        if (r < 0)
+                return log_error_errno(r, "Failed to get %smachine-ID: %m",
+                                       sd_id128_is_null(arg_app) ? "" : "app-specific ");
+
+        return id128_pretty_print(id, arg_pretty);
+}
+
+static int verb_boot_id(int argc, char **argv, void *userdata) {
+        sd_id128_t id;
+        int r;
+
+        if (sd_id128_is_null(arg_app))
+                r = sd_id128_get_boot(&id);
+        else
+                r = sd_id128_get_boot_app_specific(arg_app, &id);
+        if (r < 0)
+                return log_error_errno(r, "Failed to get %sboot-ID: %m",
+                                       sd_id128_is_null(arg_app) ? "" : "app-specific ");
+
+        return id128_pretty_print(id, arg_pretty);
+}
+
+static int verb_invocation_id(int argc, char **argv, void *userdata) {
+        sd_id128_t id;
+        int r;
+
+        if (!sd_id128_is_null(arg_app))
+                return log_error_errno(EINVAL, "Verb \"invocation-id\" cannot be combined with --app-specific=.");
+
+        r = sd_id128_get_invocation(&id);
+        if (r < 0)
+                return log_error_errno(r, "Failed to get invocation-ID: %m");
+
+        return id128_pretty_print(id, arg_pretty);
+}
+
+static int help(void) {
+        _cleanup_free_ char *link = NULL;
+        int r;
+
+        r = terminal_urlify_man("systemd-id128", "1", &link);
+        if (r < 0)
+                return log_oom();
+
+        printf("%s [OPTIONS...] {COMMAND} ...\n\n"
+               "Generate and print id128 strings.\n\n"
+               "  -h --help               Show this help\n\n"
+               "  -p --pretty             Generate samples of program code\n\n"
+               "  -a --app-specific=ID    Generate app-specific IDs\n\n"
+               "Commands:\n"
+               "  new                     Generate a new id128 string\n"
+               "  machine-id              Print the ID of current machine\n"
+               "  boot-id                 Print the ID of current boot\n"
+               "  invocation-id           Print the ID of current invocation\n"
+               "  help                    Show this help\n"
+               "\nSee the %s for details.\n"
+               , program_invocation_short_name
+               , link
+        );
+
+        return 0;
+}
+
+static int verb_help(int argc, char **argv, void *userdata) {
+        return help();
+}
+
+static int parse_argv(int argc, char *argv[]) {
+        enum {
+                ARG_VERSION = 0x100,
+        };
+
+        static const struct option options[] = {
+                { "help",         no_argument,       NULL, 'h'              },
+                { "version",      no_argument,       NULL, ARG_VERSION      },
+                { "app-specific", required_argument, NULL, 'a'              },
+                {},
+        };
+
+        int c, r;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "hpa:", options, NULL)) >= 0)
+                switch (c) {
+
+                case 'h':
+                        return help();
+
+                case ARG_VERSION:
+                        return version();
+
+                case 'p':
+                        arg_pretty = true;
+                        break;
+
+                case 'a':
+                        r = sd_id128_from_string(optarg, &arg_app);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse \"%s\" as application-ID: %m", optarg);
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        return 1;
+}
+
+static int id128_main(int argc, char *argv[]) {
+        static const Verb verbs[] = {
+                { "new",            VERB_ANY, 1,        0,  verb_new           },
+                { "machine-id",     VERB_ANY, 1,        0,  verb_machine_id    },
+                { "boot-id",        VERB_ANY, 1,        0,  verb_boot_id       },
+                { "invocation-id",  VERB_ANY, 1,        0,  verb_invocation_id },
+                { "help",           VERB_ANY, VERB_ANY, 0,  verb_help          },
+                {}
+        };
+
+        return dispatch_verb(argc, argv, verbs, NULL);
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        log_parse_environment();
+        log_open();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                goto finish;
+
+        r = id128_main(argc, argv);
+
+ finish:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}