shared: Extract common LogControl CLI code to verb-log-control.h

Let's reduce duplication by sharing common logic between all
log-target/log-level verbs.

src/shared/meson.build

@@ -301,6 +301,8 @@ shared_sources = files('''
         utmp-wtmp.h
         varlink.c
         varlink.h
+        verb-log-control.c
+        verb-log-control.h
         verbs.c
         verbs.h
         vlan-util.c

src/shared/verb-log-control.c

@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "bus-error.h"
+#include "log.h"
+#include "strv.h"
+#include "syslog-util.h"
+#include "verb-log-control.h"
+
+int verb_log_control_common(sd_bus *bus, const char *destination, const char *verb, const char *value) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        bool level = endswith(verb, "log-level");
+        const BusLocator bloc = {
+                .destination = destination,
+                .path = "/org/freedesktop/LogControl1",
+                .interface = "org.freedesktop.LogControl1",
+        };
+        int r;
+
+        assert(bus);
+        assert(endswith(verb, "log-level") || endswith(verb, "log-target"));
+
+        if (value) {
+                if (level) {
+                        r = log_level_from_string(value);
+                        if (r < 0)
+                                return log_error_errno(r, "\"%s\" is not a valid log level.", value);
+                }
+
+                r = bus_set_property(bus, &bloc,
+                                     level ? "LogLevel" : "LogTarget",
+                                     &error, "s", value);
+                if (r >= 0)
+                        return 0;
+
+                log_error_errno(r, "Failed to set log %s of %s to %s: %s",
+                                level ? "level" : "target",
+                                bloc.destination, value, bus_error_message(&error, r));
+        } else {
+                _cleanup_free_ char *t = NULL;
+
+                r = bus_get_property_string(bus, &bloc,
+                                            level ? "LogLevel" : "LogTarget",
+                                            &error, &t);
+                if (r >= 0) {
+                        puts(t);
+                        return 0;
+                }
+
+                log_error_errno(r, "Failed to get log %s of %s: %s",
+                                level ? "level" : "target",
+                                bloc.destination, bus_error_message(&error, r));
+        }
+
+        return r;
+}

src/shared/verb-log-control.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "bus-locator.h"
+
+int verb_log_control_common(sd_bus *bus, const char *destination, const char *verb, const char *value);