Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 824 insertions, 0 deletions

diff --git a/src/libsystemd/sd-bus/bus-convenience.c b/src/libsystemd/sd-bus/bus-convenience.c
new file mode 100644
index 0000000..989e577
--- /dev/null
+++ b/src/libsystemd/sd-bus/bus-convenience.c
@@ -0,0 +1,824 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "bus-internal.h"
+#include "bus-message.h"
+#include "bus-signature.h"
+#include "bus-type.h"
+#include "string-util.h"
+
+_public_ int sd_bus_message_send(sd_bus_message *reply) {
+        assert_return(reply, -EINVAL);
+        assert_return(reply->bus, -EINVAL);
+        assert_return(!bus_origin_changed(reply->bus), -ECHILD);
+
+        return sd_bus_send(reply->bus, reply, NULL);
+}
+
+_public_ int sd_bus_emit_signal_tov(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                const char *types, va_list ap) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        assert_return(bus, -EINVAL);
+        assert_return(bus = bus_resolve(bus), -ENOPKG);
+        assert_return(!bus_origin_changed(bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(bus->state))
+                return -ENOTCONN;
+
+        r = sd_bus_message_new_signal_to(bus, &m, destination, path, interface, member);
+        if (r < 0)
+                return r;
+
+        if (!isempty(types)) {
+                r = sd_bus_message_appendv(m, types, ap);
+                if (r < 0)
+                        return r;
+        }
+
+        return sd_bus_send(bus, m, NULL);
+}
+
+_public_ int sd_bus_emit_signal_to(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                const char *types, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, types);
+        r = sd_bus_emit_signal_tov(bus, destination, path, interface, member, types, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_emit_signalv(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *member,
+                const char *types, va_list ap) {
+
+    return sd_bus_emit_signal_tov(bus, NULL, path, interface, member, types, ap);
+}
+
+_public_ int sd_bus_emit_signal(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *member,
+                const char *types, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, types);
+        r = sd_bus_emit_signalv(bus, path, interface, member, types, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_call_method_asyncv(
+                sd_bus *bus,
+                sd_bus_slot **slot,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_message_handler_t callback,
+                void *userdata,
+                const char *types, va_list ap) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        assert_return(bus, -EINVAL);
+        assert_return(bus = bus_resolve(bus), -ENOPKG);
+        assert_return(!bus_origin_changed(bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(bus->state))
+                return -ENOTCONN;
+
+        r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
+        if (r < 0)
+                return r;
+
+        if (!isempty(types)) {
+                r = sd_bus_message_appendv(m, types, ap);
+                if (r < 0)
+                        return r;
+        }
+
+        return sd_bus_call_async(bus, slot, m, callback, userdata, 0);
+}
+
+_public_ int sd_bus_call_method_async(
+                sd_bus *bus,
+                sd_bus_slot **slot,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_message_handler_t callback,
+                void *userdata,
+                const char *types, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, types);
+        r = sd_bus_call_method_asyncv(bus, slot, destination, path, interface, member, callback, userdata, types, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_call_methodv(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                sd_bus_message **reply,
+                const char *types, va_list ap) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
+        if (r < 0)
+                goto fail;
+
+        if (!isempty(types)) {
+                r = sd_bus_message_appendv(m, types, ap);
+                if (r < 0)
+                        goto fail;
+        }
+
+        return sd_bus_call(bus, m, 0, error, reply);
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_call_method(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                sd_bus_message **reply,
+                const char *types, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, types);
+        r = sd_bus_call_methodv(bus, destination, path, interface, member, error, reply, types, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_reply_method_returnv(
+                sd_bus_message *call,
+                const char *types, va_list ap) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
+                return 0;
+
+        r = sd_bus_message_new_method_return(call, &m);
+        if (r < 0)
+                return r;
+
+        if (!isempty(types)) {
+                r = sd_bus_message_appendv(m, types, ap);
+                if (r < 0)
+                        return r;
+        }
+
+        return sd_bus_message_send(m);
+}
+
+_public_ int sd_bus_reply_method_return(
+                sd_bus_message *call,
+                const char *types, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, types);
+        r = sd_bus_reply_method_returnv(call, types, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_reply_method_error(
+                sd_bus_message *call,
+                const sd_bus_error *e) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
+        assert_return(sd_bus_error_is_set(e), -EINVAL);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
+                return 0;
+
+        r = sd_bus_message_new_method_error(call, &m, e);
+        if (r < 0)
+                return r;
+
+        return sd_bus_message_send(m);
+}
+
+_public_ int sd_bus_reply_method_errorfv(
+                sd_bus_message *call,
+                const char *name,
+                const char *format,
+                va_list ap) {
+
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
+                return 0;
+
+        sd_bus_error_setfv(&error, name, format, ap);
+
+        return sd_bus_reply_method_error(call, &error);
+}
+
+_public_ int sd_bus_reply_method_errorf(
+                sd_bus_message *call,
+                const char *name,
+                const char *format,
+                ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, format);
+        r = sd_bus_reply_method_errorfv(call, name, format, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_reply_method_errno(
+                sd_bus_message *call,
+                int error,
+                const sd_bus_error *p) {
+
+        _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
+                return 0;
+
+        if (sd_bus_error_is_set(p))
+                return sd_bus_reply_method_error(call, p);
+
+        sd_bus_error_set_errno(&berror, error);
+
+        return sd_bus_reply_method_error(call, &berror);
+}
+
+_public_ int sd_bus_reply_method_errnofv(
+                sd_bus_message *call,
+                int error,
+                const char *format,
+                va_list ap) {
+
+        _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
+                return 0;
+
+        sd_bus_error_set_errnofv(&berror, error, format, ap);
+
+        return sd_bus_reply_method_error(call, &berror);
+}
+
+_public_ int sd_bus_reply_method_errnof(
+                sd_bus_message *call,
+                int error,
+                const char *format,
+                ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, format);
+        r = sd_bus_reply_method_errnofv(call, error, format, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_get_property(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                sd_bus_message **reply,
+                const char *type) {
+
+        sd_bus_message *rep = NULL;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
+        bus_assert_return(member_name_is_valid(member), -EINVAL, error);
+        bus_assert_return(reply, -EINVAL, error);
+        bus_assert_return(signature_is_single(type, false), -EINVAL, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_call_method(bus, destination, path,
+                               "org.freedesktop.DBus.Properties", "Get",
+                               error, &rep,
+                               "ss", strempty(interface), member);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_enter_container(rep, 'v', type);
+        if (r < 0) {
+                sd_bus_message_unref(rep);
+                goto fail;
+        }
+
+        *reply = rep;
+        return 0;
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_get_property_trivial(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                char type, void *ptr) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
+        bus_assert_return(member_name_is_valid(member), -EINVAL, error);
+        bus_assert_return(bus_type_is_trivial(type), -EINVAL, error);
+        bus_assert_return(ptr, -EINVAL, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_enter_container(reply, 'v', CHAR_TO_STR(type));
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_read_basic(reply, type, ptr);
+        if (r < 0)
+                goto fail;
+
+        return 0;
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_get_property_string(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                char **ret) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        const char *s;
+        char *n;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
+        bus_assert_return(member_name_is_valid(member), -EINVAL, error);
+        bus_assert_return(ret, -EINVAL, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_enter_container(reply, 'v', "s");
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_read_basic(reply, 's', &s);
+        if (r < 0)
+                goto fail;
+
+        n = strdup(s);
+        if (!n) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        *ret = n;
+        return 0;
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_get_property_strv(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                char ***ret) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
+        bus_assert_return(member_name_is_valid(member), -EINVAL, error);
+        bus_assert_return(ret, -EINVAL, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_enter_container(reply, 'v', NULL);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_read_strv(reply, ret);
+        if (r < 0)
+                goto fail;
+
+        return 0;
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_set_propertyv(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                const char *type, va_list ap) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        bus_assert_return(bus, -EINVAL, error);
+        bus_assert_return(bus = bus_resolve(bus), -ENOPKG, error);
+        bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
+        bus_assert_return(member_name_is_valid(member), -EINVAL, error);
+        bus_assert_return(signature_is_single(type, false), -EINVAL, error);
+        bus_assert_return(!bus_origin_changed(bus), -ECHILD, error);
+
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
+
+        r = sd_bus_message_new_method_call(bus, &m, destination, path, "org.freedesktop.DBus.Properties", "Set");
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append(m, "ss", strempty(interface), member);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_open_container(m, 'v', type);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_appendv(m, type, ap);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                goto fail;
+
+        return sd_bus_call(bus, m, 0, error, NULL);
+
+fail:
+        return sd_bus_error_set_errno(error, r);
+}
+
+_public_ int sd_bus_set_property(
+                sd_bus *bus,
+                const char *destination,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_error *error,
+                const char *type, ...) {
+
+        va_list ap;
+        int r;
+
+        va_start(ap, type);
+        r = sd_bus_set_propertyv(bus, destination, path, interface, member, error, type, ap);
+        va_end(ap);
+
+        return r;
+}
+
+_public_ int sd_bus_query_sender_creds(sd_bus_message *call, uint64_t mask, sd_bus_creds **ret) {
+        sd_bus_creds *c;
+        int r;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+        assert_return(ret, -EINVAL);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        c = sd_bus_message_get_creds(call);
+
+        /* All data we need? */
+        if (c && (mask & ~SD_BUS_CREDS_AUGMENT & ~c->mask) == 0) {
+                *ret = sd_bus_creds_ref(c);
+                return 0;
+        }
+
+        /* No data passed? Or not enough data passed to retrieve the missing bits? */
+        if (!c || !(c->mask & SD_BUS_CREDS_PID)) {
+                /* We couldn't read anything from the call, let's try
+                 * to get it from the sender or peer. */
+
+                if (call->sender)
+                        /* There's a sender, but the creds are missing. */
+                        return sd_bus_get_name_creds(call->bus, call->sender, mask, ret);
+                else
+                        /* There's no sender. For direct connections
+                         * the credentials of the AF_UNIX peer matter,
+                         * which may be queried via sd_bus_get_owner_creds(). */
+                        return sd_bus_get_owner_creds(call->bus, mask, ret);
+        }
+
+        r = bus_creds_extend_by_pid(c, mask, ret);
+        if (r == -ESRCH) {
+                /* Process doesn't exist anymore? propagate the few things we have */
+                *ret = sd_bus_creds_ref(c);
+                return 0;
+        }
+
+        return r;
+}
+
+_public_ int sd_bus_query_sender_privilege(sd_bus_message *call, int capability) {
+        _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
+        uid_t our_uid;
+        bool know_caps = false;
+        int r;
+
+        assert_return(call, -EINVAL);
+        assert_return(call->sealed, -EPERM);
+        assert_return(call->bus, -EINVAL);
+        assert_return(!bus_origin_changed(call->bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(call->bus->state))
+                return -ENOTCONN;
+
+        if (capability >= 0) {
+
+                r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS, &creds);
+                if (r < 0)
+                        return r;
+
+                /* We cannot use augmented caps for authorization,
+                 * since then data is acquired raceful from
+                 * /proc. This can never actually happen, but let's
+                 * better be safe than sorry, and do an extra check
+                 * here. */
+                assert_return((sd_bus_creds_get_augmented_mask(creds) & SD_BUS_CREDS_EFFECTIVE_CAPS) == 0, -EPERM);
+
+                r = sd_bus_creds_has_effective_cap(creds, capability);
+                if (r > 0)
+                        return 1;
+                if (r == 0)
+                        know_caps = true;
+        } else {
+                r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID, &creds);
+                if (r < 0)
+                        return r;
+        }
+
+        /* Now, check the UID, but only if the capability check wasn't
+         * sufficient */
+        our_uid = getuid();
+        if (our_uid != 0 || !know_caps || capability < 0) {
+                uid_t sender_uid;
+
+                /* We cannot use augmented uid/euid for authorization,
+                 * since then data is acquired raceful from
+                 * /proc. This can never actually happen, but let's
+                 * better be safe than sorry, and do an extra check
+                 * here. */
+                assert_return((sd_bus_creds_get_augmented_mask(creds) & (SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID)) == 0, -EPERM);
+
+                /* Try to use the EUID, if we have it. */
+                r = sd_bus_creds_get_euid(creds, &sender_uid);
+                if (r < 0)
+                        r = sd_bus_creds_get_uid(creds, &sender_uid);
+
+                if (r >= 0) {
+                        /* Sender has same UID as us, then let's grant access */
+                        if (sender_uid == our_uid)
+                                return 1;
+
+                        /* Sender is root, we are not root. */
+                        if (our_uid != 0 && sender_uid == 0)
+                                return 1;
+                }
+        }
+
+        return 0;
+}
+
+#define make_expression(sender, path, interface, member)        \
+        strjoina(                                               \
+                "type='signal'",                                \
+                sender ? ",sender='" : "",                      \
+                sender ?: "",                                   \
+                sender ? "'" : "",                              \
+                path ? ",path='" : "",                          \
+                path ?: "",                                     \
+                path ? "'" : "",                                \
+                interface ? ",interface='" : "",                \
+                interface ?: "",                                \
+                interface ? "'" : "",                           \
+                member ? ",member='" : "",                      \
+                member ?: "",                                   \
+                member ? "'" : ""                               \
+        )
+
+_public_ int sd_bus_match_signal(
+                sd_bus *bus,
+                sd_bus_slot **ret,
+                const char *sender,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_message_handler_t callback,
+                void *userdata) {
+
+        const char *expression;
+
+        assert_return(bus, -EINVAL);
+        assert_return(bus = bus_resolve(bus), -ENOPKG);
+        assert_return(!bus_origin_changed(bus), -ECHILD);
+        assert_return(!sender || service_name_is_valid(sender), -EINVAL);
+        assert_return(!path || object_path_is_valid(path), -EINVAL);
+        assert_return(!interface || interface_name_is_valid(interface), -EINVAL);
+        assert_return(!member || member_name_is_valid(member), -EINVAL);
+
+        expression = make_expression(sender, path, interface, member);
+
+        return sd_bus_add_match(bus, ret, expression, callback, userdata);
+}
+
+_public_ int sd_bus_match_signal_async(
+                sd_bus *bus,
+                sd_bus_slot **ret,
+                const char *sender,
+                const char *path,
+                const char *interface,
+                const char *member,
+                sd_bus_message_handler_t callback,
+                sd_bus_message_handler_t install_callback,
+                void *userdata) {
+
+        const char *expression;
+
+        assert_return(bus, -EINVAL);
+        assert_return(bus = bus_resolve(bus), -ENOPKG);
+        assert_return(!bus_origin_changed(bus), -ECHILD);
+        assert_return(!sender || service_name_is_valid(sender), -EINVAL);
+        assert_return(!path || object_path_is_valid(path), -EINVAL);
+        assert_return(!interface || interface_name_is_valid(interface), -EINVAL);
+        assert_return(!member || member_name_is_valid(member), -EINVAL);
+
+        expression = make_expression(sender, path, interface, member);
+
+        return sd_bus_add_match_async(bus, ret, expression, callback, install_callback, userdata);
+}