libsystemd-bus: use assert_return

[elogind.git] / src / libsystemd-bus / bus-message.c

diff --git a/src/libsystemd-bus/bus-message.c b/src/libsystemd-bus/bus-message.c
index 547fd5f8c075fe40290419710674442a55cbf81b..5e355127b0cb119f460738c1c9c346a5a3114b97 100644 (file)
--- a/src/libsystemd-bus/bus-message.c
+++ b/src/libsystemd-bus/bus-message.c
@@ -161,9 +161,7 @@ static void *message_extend_fields(sd_bus_message *m, size_t align, size_t sz, b
         size_t old_size, new_size, start;
 
         assert(m);
         size_t old_size, new_size, start;
 
         assert(m);

-
-        if (m->poisoned)
-                return NULL;
+        assert_return(!m->poisoned, NULL);

 
         old_size = sizeof(struct bus_header) + m->header->fields_size;
         start = ALIGN_TO(old_size, align);
 
         old_size = sizeof(struct bus_header) + m->header->fields_size;
         start = ALIGN_TO(old_size, align);


@@ -989,9 +987,7 @@ struct bus_body_part *message_append_part(sd_bus_message *m) {
         struct bus_body_part *part;
 
         assert(m);
         struct bus_body_part *part;
 
         assert(m);

-
-        if (m->poisoned)
-                return NULL;
+        assert_return(!m->poisoned, NULL);

 
         if (m->n_body_parts <= 0) {
                 part = &m->body;
 
         if (m->n_body_parts <= 0) {
                 part = &m->body;


@@ -1131,18 +1127,14 @@ static void message_extend_containers(sd_bus_message *m, size_t expand) {
 }
 
 static void *message_extend_body(sd_bus_message *m, size_t align, size_t sz, bool add_offset) {
 }
 
 static void *message_extend_body(sd_bus_message *m, size_t align, size_t sz, bool add_offset) {

-        struct bus_body_part *part = NULL;
-        size_t start_body, end_body, padding, start_part, end_part, added;
-        bool add_new_part;
+        size_t start_body, end_body, padding, added;

         void *p;
         int r;
 
         assert(m);
         assert(align > 0);
         assert(!m->sealed);
         void *p;
         int r;
 
         assert(m);
         assert(align > 0);
         assert(!m->sealed);

-
-        if (m->poisoned)
-                return NULL;
+        assert_return(!m->poisoned, NULL);

 
         start_body = ALIGN_TO((size_t) m->header->body_size, align);
         end_body = start_body + sz;
 
         start_body = ALIGN_TO((size_t) m->header->body_size, align);
         end_body = start_body + sz;


@@ -1156,54 +1148,61 @@ static void *message_extend_body(sd_bus_message *m, size_t align, size_t sz, boo
                 return NULL;
         }
 
                 return NULL;
         }
 

-        add_new_part =
-                m->n_body_parts <= 0 ||
-                m->body_end->sealed ||
-                padding != ALIGN_TO(m->body_end->size, align) - m->body_end->size;
+        if (added > 0) {
+                struct bus_body_part *part = NULL;
+                bool add_new_part;
+
+                add_new_part =
+                        m->n_body_parts <= 0 ||
+                        m->body_end->sealed ||
+                        padding != ALIGN_TO(m->body_end->size, align) - m->body_end->size;
+
+                if (add_new_part) {
+                        if (padding > 0) {
+                                part = message_append_part(m);
+                                if (!part)
+                                        return NULL;
+
+                                part_zero(part, padding);
+                        }

 
 

-        if (add_new_part) {
-                if (padding > 0) {

                         part = message_append_part(m);
                         if (!part)
                                 return NULL;
 
                         part = message_append_part(m);
                         if (!part)
                                 return NULL;
 

-                        part_zero(part, padding);
-                }
+                        r = part_make_space(m, part, sz, &p);
+                        if (r < 0)
+                                return NULL;
+                } else {
+                        struct bus_container *c;
+                        void *op;
+                        size_t os, start_part, end_part;

 
 

-                part = message_append_part(m);
-                if (!part)
-                        return NULL;
+                        part = m->body_end;
+                        op = part->data;
+                        os = part->size;

 
 

-                r = part_make_space(m, part, sz, &p);
-                if (r < 0)
-                        return NULL;
-        } else {
-                struct bus_container *c;
-                void *op;
-                size_t os;
+                        start_part = ALIGN_TO(part->size, align);
+                        end_part = start_part + sz;

 
 

-                part = m->body_end;
-                op = part->data;
-                os = part->size;
+                        r = part_make_space(m, part, end_part, &p);
+                        if (r < 0)
+                                return NULL;

 
 

-                start_part = ALIGN_TO(part->size, align);
-                end_part = start_part + sz;
+                        if (padding > 0) {
+                                memset(p, 0, padding);
+                                p = (uint8_t*) p + padding;
+                        }

 
 

-                r = part_make_space(m, part, end_part, &p);
-                if (r < 0)
-                        return NULL;
+                        /* Readjust pointers */
+                        for (c = m->containers; c < m->containers + m->n_containers; c++)
+                                c->array_size = adjust_pointer(c->array_size, op, os, part->data);

 
 

-                if (padding > 0) {
-                        memset(p, 0, padding);
-                        p = (uint8_t*) p + padding;
+                        m->error.message = (const char*) adjust_pointer(m->error.message, op, os, part->data);

                 }
                 }

-
-                /* Readjust pointers */
-                for (c = m->containers; c < m->containers + m->n_containers; c++)
-                        c->array_size = adjust_pointer(c->array_size, op, os, part->data);
-
-                m->error.message = (const char*) adjust_pointer(m->error.message, op, os, part->data);
-        }
+        } else
+                /* Return something that is not NULL and is aligned */
+                p = (uint8_t *) NULL + align;

 
         m->header->body_size = end_body;
         message_extend_containers(m, added);
 
         m->header->body_size = end_body;
         message_extend_containers(m, added);


@@ -1889,9 +1888,7 @@ _public_ int sd_bus_message_open_container(
 }
 
 static size_t determine_word_size(size_t sz, size_t extra) {
 }
 
 static size_t determine_word_size(size_t sz, size_t extra) {

-        if (sz <= 0 && extra == 0)
-                return 0;
-        else if (sz + extra <= 0xFF)
+        if (sz + extra <= 0xFF)

                 return 1;
         else if (sz + extra*2 <= 0xFFFF)
                 return 2;
                 return 1;
         else if (sz + extra*2 <= 0xFFFF)
                 return 2;


@@ -2021,7 +2018,7 @@ static int bus_message_close_struct(sd_bus_message *m, struct bus_container *c,
         if (!BUS_MESSAGE_IS_GVARIANT(m))
                 return 0;
 
         if (!BUS_MESSAGE_IS_GVARIANT(m))
                 return 0;
 

-        p = c->signature;
+        p = strempty(c->signature);

         while (*p != 0) {
                 size_t n;
 
         while (*p != 0) {
                 size_t n;
 


@@ -2069,7 +2066,7 @@ static int bus_message_close_struct(sd_bus_message *m, struct bus_container *c,
                 if (!a)
                         return -ENOMEM;
 
                 if (!a)
                         return -ENOMEM;
 

-                p = c->signature;
+                p = strempty(c->signature);

                 for (i = 0, j = 0; i < c->n_offsets; i++) {
                         unsigned k;
                         size_t n;
                 for (i = 0, j = 0; i < c->n_offsets; i++) {
                         unsigned k;
                         size_t n;


@@ -2399,10 +2396,12 @@ _public_ int sd_bus_message_append_array_space(
 
         assert_return(m, -EINVAL);
         assert_return(!m->sealed, -EPERM);
 
         assert_return(m, -EINVAL);
         assert_return(!m->sealed, -EPERM);

-        assert_return(bus_type_is_trivial(type), -EINVAL);
+        assert_return(bus_type_is_trivial(type) && type != SD_BUS_TYPE_BOOLEAN, -EINVAL);

         assert_return(ptr || size == 0, -EINVAL);
         assert_return(!m->poisoned, -ESTALE);
 
         assert_return(ptr || size == 0, -EINVAL);
         assert_return(!m->poisoned, -ESTALE);
 

+        /* alignment and size of the trivial types (except bool) is
+         * identical for gvariant and dbus1 marshalling */

         align = bus_type_get_alignment(type);
         sz = bus_type_get_size(type);
 
         align = bus_type_get_alignment(type);
         sz = bus_type_get_size(type);
 


@@ -2549,8 +2548,8 @@ _public_ int sd_bus_message_append_array_memfd(sd_bus_message *m,
         part->size = size;
         copy_fd = -1;
 
         part->size = size;
         copy_fd = -1;
 

-        message_extend_containers(m, size);

         m->header->body_size += size;
         m->header->body_size += size;

+        message_extend_containers(m, size);

 
         return sd_bus_message_close_container(m);
 }
 
         return sd_bus_message_close_container(m);
 }


@@ -2964,8 +2963,12 @@ static int container_next_item(sd_bus_message *m, struct bus_container *c, size_
                         *rindex = ALIGN_TO(c->offsets[c->offset_index], alignment);
                         c->item_size = c->offsets[c->offset_index+1] - *rindex;
                 } else {
                         *rindex = ALIGN_TO(c->offsets[c->offset_index], alignment);
                         c->item_size = c->offsets[c->offset_index+1] - *rindex;
                 } else {

+
+                        if (c->offset_index+1 >= (c->end-c->begin)/sz)
+                                goto end;
+

                         /* Fixed-size array */
                         /* Fixed-size array */

-                        *rindex += sz;
+                        *rindex = c->begin + (c->offset_index+1) * sz;

                         c->item_size = sz;
                 }
 
                         c->item_size = sz;
                 }
 


@@ -3033,9 +3036,6 @@ static int message_peek_body(
         assert(rindex);
         assert(align > 0);
 
         assert(rindex);
         assert(align > 0);
 

-        if (message_end_of_array(m, *rindex))
-                return 0;
-

         start = ALIGN_TO((size_t) *rindex, align);
         padding = start - *rindex;
         end = start + nbytes;
         start = ALIGN_TO((size_t) *rindex, align);
         padding = start - *rindex;
         end = start + nbytes;


@@ -3055,7 +3055,7 @@ static int message_peek_body(
         }
 
         part = find_part(m, start, nbytes, (void**) &q);
         }
 
         part = find_part(m, start, nbytes, (void**) &q);

-        if (!part || !q)
+        if (!part || (nbytes > 0 && !q))

                 return -EBADMSG;
 
         *rindex = end;
                 return -EBADMSG;
 
         *rindex = end;


@@ -3063,7 +3063,7 @@ static int message_peek_body(
         if (ret)
                 *ret = q;
 
         if (ret)
                 *ret = q;
 

-        return 1;
+        return 0;

 }
 
 static bool validate_nul(const char *s, size_t l) {
 }
 
 static bool validate_nul(const char *s, size_t l) {


@@ -3142,7 +3142,7 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         bool ok;
 
                         r = message_peek_body(m, &rindex, 1, c->item_size, &q);
                         bool ok;
 
                         r = message_peek_body(m, &rindex, 1, c->item_size, &q);

-                        if (r <= 0)
+                        if (r < 0)

                                 return r;
 
                         if (type == SD_BUS_TYPE_STRING)
                                 return r;
 
                         if (type == SD_BUS_TYPE_STRING)


@@ -3169,7 +3169,7 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         assert(align > 0);
 
                         r = message_peek_body(m, &rindex, align, c->item_size, &q);
                         assert(align > 0);
 
                         r = message_peek_body(m, &rindex, align, c->item_size, &q);

-                        if (r <= 0)
+                        if (r < 0)

                                 return r;
 
                         switch (type) {
                                 return r;
 
                         switch (type) {


@@ -3233,15 +3233,13 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         bool ok;
 
                         r = message_peek_body(m, &rindex, 4, 4, &q);
                         bool ok;
 
                         r = message_peek_body(m, &rindex, 4, 4, &q);

-                        if (r <= 0)
+                        if (r < 0)

                                 return r;
 
                         l = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
                         r = message_peek_body(m, &rindex, 1, l+1, &q);
                         if (r < 0)
                                 return r;
                                 return r;
 
                         l = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
                         r = message_peek_body(m, &rindex, 1, l+1, &q);
                         if (r < 0)
                                 return r;

-                        if (r == 0)
-                                return -EBADMSG;

 
                         if (type == SD_BUS_TYPE_OBJECT_PATH)
                                 ok = validate_object_path(q, l);
 
                         if (type == SD_BUS_TYPE_OBJECT_PATH)
                                 ok = validate_object_path(q, l);


@@ -3257,15 +3255,13 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         uint8_t l;
 
                         r = message_peek_body(m, &rindex, 1, 1, &q);
                         uint8_t l;
 
                         r = message_peek_body(m, &rindex, 1, 1, &q);

-                        if (r <= 0)
+                        if (r < 0)

                                 return r;
 
                         l = *(uint8_t*) q;
                         r = message_peek_body(m, &rindex, 1, l+1, &q);
                         if (r < 0)
                                 return r;
                                 return r;
 
                         l = *(uint8_t*) q;
                         r = message_peek_body(m, &rindex, 1, l+1, &q);
                         if (r < 0)
                                 return r;

-                        if (r == 0)
-                                return -EBADMSG;

 
                         if (!validate_signature(q, l))
                                 return -EBADMSG;
 
                         if (!validate_signature(q, l))
                                 return -EBADMSG;


@@ -3283,7 +3279,7 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         assert(sz > 0);
 
                         r = message_peek_body(m, &rindex, align, sz, &q);
                         assert(sz > 0);
 
                         r = message_peek_body(m, &rindex, align, sz, &q);

-                        if (r <= 0)
+                        if (r < 0)

                                 return r;
 
                         switch (type) {
                                 return r;
 
                         switch (type) {


@@ -3382,7 +3378,7 @@ static int bus_message_enter_array(
                 /* dbus1 */
 
                 r = message_peek_body(m, &rindex, 4, 4, &q);
                 /* dbus1 */
 
                 r = message_peek_body(m, &rindex, 4, 4, &q);

-                if (r <= 0)
+                if (r < 0)

                         return r;
 
                 if (BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q) > BUS_ARRAY_MAX_SIZE)
                         return r;
 
                 if (BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q) > BUS_ARRAY_MAX_SIZE)


@@ -3395,8 +3391,6 @@ static int bus_message_enter_array(
                 r = message_peek_body(m, &rindex, alignment, 0, NULL);
                 if (r < 0)
                         return r;
                 r = message_peek_body(m, &rindex, alignment, 0, NULL);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 *array_size = (uint32_t*) q;
 
 
                 *array_size = (uint32_t*) q;
 


@@ -3425,8 +3419,6 @@ static int bus_message_enter_array(
                 r = message_peek_body(m, &where, 1, sz, &q);
                 if (r < 0)
                         return r;
                 r = message_peek_body(m, &where, 1, sz, &q);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 framing = read_word_le(q, sz);
                 if (framing > c->item_size - sz)
 
                 framing = read_word_le(q, sz);
                 if (framing > c->item_size - sz)


@@ -3440,8 +3432,6 @@ static int bus_message_enter_array(
                 r = message_peek_body(m, &where, 1, *n_offsets * sz, &q);
                 if (r < 0)
                         return r;
                 r = message_peek_body(m, &where, 1, *n_offsets * sz, &q);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 *offsets = new(size_t, *n_offsets);
                 if (!*offsets)
 
                 *offsets = new(size_t, *n_offsets);
                 if (!*offsets)


@@ -3512,8 +3502,6 @@ static int bus_message_enter_variant(
                 r = message_peek_body(m, &where, 1, 1+k, &q);
                 if (r < 0)
                         return r;
                 r = message_peek_body(m, &where, 1, 1+k, &q);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 if (*(char*) q != 0)
                         return -EBADMSG;
 
                 if (*(char*) q != 0)
                         return -EBADMSG;


@@ -3527,15 +3515,11 @@ static int bus_message_enter_variant(
                 r = message_peek_body(m, &rindex, 1, 1, &q);
                 if (r < 0)
                         return r;
                 r = message_peek_body(m, &rindex, 1, 1, &q);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 l = *(uint8_t*) q;
                 r = message_peek_body(m, &rindex, 1, l+1, &q);
                 if (r < 0)
                         return r;
 
                 l = *(uint8_t*) q;
                 r = message_peek_body(m, &rindex, 1, l+1, &q);
                 if (r < 0)
                         return r;

-                if (r == 0)
-                        return -EBADMSG;

 
                 if (!validate_signature(q, l))
                         return -EBADMSG;
 
                 if (!validate_signature(q, l))
                         return -EBADMSG;


@@ -3568,12 +3552,20 @@ static int build_struct_offsets(
         int r;
 
         assert(m);
         int r;
 
         assert(m);

-        assert(signature);

         assert(item_size);
         assert(offsets);
         assert(n_offsets);
 
         assert(item_size);
         assert(offsets);
         assert(n_offsets);
 

+        if (isempty(signature)) {
+                *item_size = 0;
+                *offsets = NULL;
+                *n_offsets = 0;
+                return 0;
+        }
+

         sz = determine_word_size(size, 0);
         sz = determine_word_size(size, 0);

+        if (sz <= 0)
+                return -EBADMSG;

 
         /* First, loop over signature and count variable elements and
          * elements in general. We use this to know how large the
 
         /* First, loop over signature and count variable elements and
          * elements in general. We use this to know how large the


@@ -3613,8 +3605,6 @@ static int build_struct_offsets(
         r = message_peek_body(m, &where, 1, n_variable * sz, &q);
         if (r < 0)
                 return r;
         r = message_peek_body(m, &where, 1, n_variable * sz, &q);
         if (r < 0)
                 return r;

-        if (r == 0)
-                return -EBADMSG;

 
         v = n_variable;
 
 
         v = n_variable;
 


@@ -3704,7 +3694,7 @@ static int enter_struct_or_dict_entry(
 
                 /* dbus1 */
                 r = message_peek_body(m, &m->rindex, 8, 0, NULL);
 
                 /* dbus1 */
                 r = message_peek_body(m, &m->rindex, 8, 0, NULL);

-                if (r <= 0)
+                if (r < 0)

                         return r;
 
         } else if (c->item_size <= 0) {
                         return r;
 
         } else if (c->item_size <= 0) {


@@ -3823,7 +3813,7 @@ _public_ int sd_bus_message_enter_container(sd_bus_message *m,
 
                 /* Allow entering into anonymous containers */
                 r = sd_bus_message_peek_type(m, &tt, &cc);
 
                 /* Allow entering into anonymous containers */
                 r = sd_bus_message_peek_type(m, &tt, &cc);

-                if (r <= 0)
+                if (r < 0)

                         return r;
 
                 if (type != 0 && type != tt)
                         return r;
 
                 if (type != 0 && type != tt)


@@ -3913,6 +3903,7 @@ _public_ int sd_bus_message_enter_container(sd_bus_message *m,
 
 _public_ int sd_bus_message_exit_container(sd_bus_message *m) {
         struct bus_container *c;
 
 _public_ int sd_bus_message_exit_container(sd_bus_message *m) {
         struct bus_container *c;

+        unsigned saved;

         int r;
 
         assert_return(m, -EINVAL);
         int r;
 
         assert_return(m, -EINVAL);


@@ -3944,7 +3935,10 @@ _public_ int sd_bus_message_exit_container(sd_bus_message *m) {
 
         c = message_get_container(m);
 
 
         c = message_get_container(m);
 

+        saved = c->index;
+        c->index = c->saved_index;

         r = container_next_item(m, c, &m->rindex);
         r = container_next_item(m, c, &m->rindex);

+        c->index = saved;

         if (r < 0)
                 return r;
 
         if (r < 0)
                 return r;
 


@@ -4076,8 +4070,6 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
                                         r = message_peek_body(m, &where, 1, k, &q);
                                         if (r < 0)
                                                 return r;
                                         r = message_peek_body(m, &where, 1, k, &q);
                                         if (r < 0)
                                                 return r;

-                                        if (r == 0)
-                                                goto eof;

 
                                         if (*(char*) q == 0)
                                                 break;
 
                                         if (*(char*) q == 0)
                                                 break;


@@ -4102,15 +4094,11 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
                                 r = message_peek_body(m, &rindex, 1, 1, &q);
                                 if (r < 0)
                                         return r;
                                 r = message_peek_body(m, &rindex, 1, 1, &q);
                                 if (r < 0)
                                         return r;

-                                if (r == 0)
-                                        goto eof;

 
                                 l = *(uint8_t*) q;
                                 r = message_peek_body(m, &rindex, 1, l+1, &q);
                                 if (r < 0)
                                         return r;
 
                                 l = *(uint8_t*) q;
                                 r = message_peek_body(m, &rindex, 1, l+1, &q);
                                 if (r < 0)
                                         return r;

-                                if (r == 0)
-                                        return -EBADMSG;

 
                                 if (!validate_signature(q, l))
                                         return -EBADMSG;
 
                                 if (!validate_signature(q, l))
                                         return -EBADMSG;


@@ -4154,6 +4142,9 @@ _public_ int sd_bus_message_rewind(sd_bus_message *m, int complete) {
                 m->rindex = c->begin;
         }
 
                 m->rindex = c->begin;
         }
 

+        c->offset_index = 0;
+        c->item_size = c->n_offsets > 0 ? c->offsets[0] : c->end;
+

         return !isempty(c->signature);
 }
 
         return !isempty(c->signature);
 }
 


@@ -4540,7 +4531,7 @@ _public_ int sd_bus_message_read_array(sd_bus_message *m,
                 if (align < 0)
                         return align;
 
                 if (align < 0)
                         return align;
 

-                sz = c->item_size;
+                sz = c->end - c->begin;

         } else {
                 align = bus_type_get_alignment(type);
                 if (align < 0)
         } else {
                 align = bus_type_get_alignment(type);
                 if (align < 0)


@@ -4557,10 +4548,6 @@ _public_ int sd_bus_message_read_array(sd_bus_message *m,
                 r = message_peek_body(m, &m->rindex, align, sz, &p);
                 if (r < 0)
                         goto fail;
                 r = message_peek_body(m, &m->rindex, align, sz, &p);
                 if (r < 0)
                         goto fail;

-                if (r == 0) {
-                        r = -EBADMSG;
-                        goto fail;
-                }

         }
 
         r = sd_bus_message_exit_container(m);
         }
 
         r = sd_bus_message_exit_container(m);


@@ -4856,7 +4843,7 @@ int bus_message_parse_fields(sd_bus_message *m) {
         uint32_t unix_fds = 0;
         void *offsets = NULL;
         unsigned n_offsets = 0;
         uint32_t unix_fds = 0;
         void *offsets = NULL;
         unsigned n_offsets = 0;

-        size_t sz;
+        size_t sz = 0;

         unsigned i = 0;
 
         assert(m);
         unsigned i = 0;
 
         assert(m);


@@ -5090,9 +5077,6 @@ int bus_message_parse_fields(sd_bus_message *m) {
         if (m->n_fds != unix_fds)
                 return -EBADMSG;
 
         if (m->n_fds != unix_fds)
                 return -EBADMSG;
 

-        if (isempty(m->root_container.signature) != (BUS_MESSAGE_BODY_SIZE(m) == 0))
-                return -EBADMSG;
-

         switch (m->header->type) {
 
         case SD_BUS_MESSAGE_SIGNAL:
         switch (m->header->type) {
 
         case SD_BUS_MESSAGE_SIGNAL:


@@ -5307,7 +5291,7 @@ _public_ const char* sd_bus_message_get_signature(sd_bus_message *m, int complet
         assert_return(m, NULL);
 
         c = complete ? &m->root_container : message_get_container(m);
         assert_return(m, NULL);
 
         c = complete ? &m->root_container : message_get_container(m);

-        return c->signature ?: "";
+        return strempty(c->signature);

 }
 
 _public_ int sd_bus_message_copy(sd_bus_message *m, sd_bus_message *source, int all) {
 }
 
 _public_ int sd_bus_message_copy(sd_bus_message *m, sd_bus_message *source, int all) {