systemctl: add option --when for scheduled shutdown

Pass an empty string or "cancel" will cancel the action.
Pass "show" will show the scheduled actions.

Replaces #17258

src/systemctl/systemctl-logind.c

@@ -356,7 +356,7 @@ int logind_show_shutdown(void) {
         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         sd_bus *bus;
-        const char *action = NULL;
+        const char *action, *pretty_action;
         uint64_t elapse;
         int r;
 
@@ -376,17 +376,23 @@ int logind_show_shutdown(void) {
                 return log_error_errno(SYNTHETIC_ERRNO(ENODATA), "No scheduled shutdown.");
 
         if (STR_IN_SET(action, "halt", "poweroff", "exit"))
-                action = "Shutdown";
+                pretty_action = "Shutdown";
         else if (streq(action, "kexec"))
-                action = "Reboot via kexec";
+                pretty_action = "Reboot via kexec";
         else if (streq(action, "reboot"))
-                action = "Reboot";
+                pretty_action = "Reboot";
+        else /* If we don't recognize the action string, we'll show it as-is */
+                pretty_action = action;
 
-        /* If we don't recognize the action string, we'll show it as-is */
-
-        log_info("%s scheduled for %s, use 'shutdown -c' to cancel.",
-                 action,
-                 FORMAT_TIMESTAMP_STYLE(elapse, arg_timestamp_style));
+        if (arg_action == ACTION_SYSTEMCTL)
+                log_info("%s scheduled for %s, use 'systemctl %s --when=cancel' to cancel.",
+                         pretty_action,
+                         FORMAT_TIMESTAMP_STYLE(elapse, arg_timestamp_style),
+                         action);
+        else
+                log_info("%s scheduled for %s, use 'shutdown -c' to cancel.",
+                         pretty_action,
+                         FORMAT_TIMESTAMP_STYLE(elapse, arg_timestamp_style));
 
         return 0;
 #else

src/systemctl/systemctl-start-special.c

@@ -197,22 +197,33 @@ int verb_start_special(int argc, char *argv[], void *userdata) {
                            ACTION_POWEROFF,
                            ACTION_REBOOT,
                            ACTION_KEXEC,
-                           ACTION_HALT,
-                           ACTION_SUSPEND,
-                           ACTION_HIBERNATE,
-                           ACTION_HYBRID_SLEEP,
-                           ACTION_SUSPEND_THEN_HIBERNATE)) {
+                           ACTION_HALT)) {
 
-                        r = logind_reboot(a);
-                        if (r >= 0)
-                                return r;
-                        if (IN_SET(r, -EACCES, -EOPNOTSUPP, -EINPROGRESS))
-                                /* Requested operation requires auth, is not supported or already in progress */
+                        if (arg_when == 0)
+                                r = logind_reboot(a);
+                        else if (arg_when != USEC_INFINITY)
+                                r = logind_schedule_shutdown(a);
+                        else /* arg_when == USEC_INFINITY */
+                                r = logind_cancel_shutdown();
+                        if (r >= 0 || IN_SET(r, -EACCES, -EOPNOTSUPP, -EINPROGRESS))
+                                /* The latter indicates that the requested operation requires auth,
+                                 * is not supported or already in progress, in which cases we ignore the error. */
                                 return r;
 
                         /* On all other errors, try low-level operation. In order to minimize the difference
                          * between operation with and without logind, we explicitly enable non-blocking mode
                          * for this, as logind's shutdown operations are always non-blocking. */
+                        arg_no_block = true;
+
+                } else if (IN_SET(a,
+                                  ACTION_SUSPEND,
+                                  ACTION_HIBERNATE,
+                                  ACTION_HYBRID_SLEEP,
+                                  ACTION_SUSPEND_THEN_HIBERNATE)) {
+
+                        r = logind_reboot(a);
+                        if (r >= 0 || IN_SET(r, -EACCES, -EOPNOTSUPP, -EINPROGRESS))
+                                return r;
 
                         arg_no_block = true;
 

src/systemctl/systemctl.c

@@ -323,6 +323,8 @@ static int systemctl_help(void) {
                "     --mkdir             Create directory before mounting, if missing\n"
                "     --marked            Restart/reload previously marked units\n"
                "     --drop-in=NAME      Edit unit files using the specified drop-in file name\n"
+               "     --when=TIME         Schedule halt/power-off/reboot/kexec action after\n"
+               "                         a certain timestamp\n"
                "\nSee the %2$s for details.\n",
                program_invocation_short_name,
                link,
@@ -447,6 +449,7 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                 ARG_MARKED,
                 ARG_NO_WARN,
                 ARG_DROP_IN,
+                ARG_WHEN,
         };
 
         static const struct option options[] = {
@@ -511,6 +514,7 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                 { "mkdir",               no_argument,       NULL, ARG_MKDIR               },
                 { "marked",              no_argument,       NULL, ARG_MARKED              },
                 { "drop-in",             required_argument, NULL, ARG_DROP_IN             },
+                { "when",                required_argument, NULL, ARG_WHEN                },
                 {}
         };
 
@@ -975,6 +979,30 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                         arg_drop_in = optarg;
                         break;
 
+                case ARG_WHEN:
+                        if (streq(optarg, "show")) {
+                                r = logind_show_shutdown();
+                                if (r < 0 && r != -ENODATA)
+                                        return r;
+
+                                return 0;
+                        }
+
+                        if (STR_IN_SET(optarg, "", "cancel")) {
+                                arg_when = USEC_INFINITY;
+                                break;
+                        }
+
+                        r = parse_timestamp(optarg, &arg_when);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse --when= argument '%s': %m", optarg);
+
+                        if (!timestamp_is_set(arg_when))
+                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "Invalid timestamp '%s' specified for --when=.", optarg);
+
+                        break;
+
                 case '.':
                         /* Output an error mimicking getopt, and print a hint afterwards */
                         log_error("%s: invalid option -- '.'", program_invocation_name);