In gvariant, all fixed-size objects need to be sized a multiple of their
alignment. If a structure has only fixed-size members, it is required to
be fixed size itself. If you imagine a structure like (ty), you have an
8-byte member followed by an 1-byte member. Hence, the overall inner-size
is 9. The alignment of the object is 8, though. Therefore, the specs
mandates final padding after fixed-size structures, to make sure it's
sized a multiple of its alignment (=> 16).
On the gvariant decoder side, we already account for this in
bus_gvariant_get_size(), as we apply overall padding to the size of the
structure. Therefore, our decoder correctly skips such final padding when
parsing fixed-size structure.
On the gvariant encoder side, however, we don't account for this final
padding. This patch fixes the structure and dict-entry encoders to
properly place such padding at the end of non-uniform fixed-size
structures.
The problem can be easily seen by running:
$ busctl --user monitor
and
$ busctl call --user org.freedesktop.systemd1 / org.foobar foobar "(ty)" 777 8
The monitor will fail to parse the message and print an error. With this
patch applied, everything works fine again.
This patch also adds a bunch of test-cases to force non-uniform
structures with non-pre-aligned positions.
Thanks to Jan Alexander Steffens <jan.steffens@gmail.com> for spotting
this and narrowing it down to non-uniform gvariant structures. Fixes #597.
}
static int bus_message_close_struct(sd_bus_message *m, struct bus_container *c, bool add_offset) {
}
static int bus_message_close_struct(sd_bus_message *m, struct bus_container *c, bool add_offset) {
+ bool fixed_size = true;
size_t n_variable = 0;
unsigned i = 0;
const char *p;
size_t n_variable = 0;
unsigned i = 0;
const char *p;
/* We need to add an offset for each item that has a
* variable size and that is not the last one in the
* list */
/* We need to add an offset for each item that has a
* variable size and that is not the last one in the
* list */
+ if (r == 0)
+ fixed_size = false;
if (r == 0 && p[n] != 0)
n_variable++;
if (r == 0 && p[n] != 0)
n_variable++;
assert(c->need_offsets || n_variable == 0);
if (n_variable <= 0) {
assert(c->need_offsets || n_variable == 0);
if (n_variable <= 0) {
- a = message_extend_body(m, 1, 0, add_offset, false);
+ int alignment = 1;
+
+ /* Structures with fixed-size members only have to be
+ * fixed-size themselves. But gvariant requires all fixed-size
+ * elements to be sized a multiple of their alignment. Hence,
+ * we must *always* add final padding after the last member so
+ * the overall size of the structure is properly aligned. */
+ if (fixed_size)
+ alignment = bus_gvariant_get_alignment(strempty(c->signature));
+
+ assert(alignment > 0);
+
+ a = message_extend_body(m, alignment, 0, add_offset, false);
if (!a)
return -ENOMEM;
} else {
if (!a)
return -ENOMEM;
} else {
r = sd_bus_message_append(m, "a{yv}", 2, 3, "s", "foo", 5, "s", "waldo");
assert_se(r >= 0);
r = sd_bus_message_append(m, "a{yv}", 2, 3, "s", "foo", 5, "s", "waldo");
assert_se(r >= 0);
+ r = sd_bus_message_append(m, "y(ty)y(yt)y", 8, 777, 7, 9, 77, 7777, 10);
+ assert_se(r >= 0);
+
r = sd_bus_message_append(m, "ba(ss)", 255, 3, "aaa", "1", "bbb", "2", "ccc", "3");
assert_se(r >= 0);
r = sd_bus_message_append(m, "ba(ss)", 255, 3, "aaa", "1", "bbb", "2", "ccc", "3");
assert_se(r >= 0);
assert_se(v == 5);
assert_se(streq(y, "waldo"));
assert_se(v == 5);
assert_se(streq(y, "waldo"));
+ r = sd_bus_message_read(m, "y(ty)", &v, &u64, &u);
+ assert_se(r > 0);
+ assert_se(v == 8);
+ assert_se(u64 == 777);
+ assert_se(u == 7);
+
+ r = sd_bus_message_read(m, "y(yt)", &v, &u, &u64);
+ assert_se(r > 0);
+ assert_se(v == 9);
+ assert_se(u == 77);
+ assert_se(u64 == 7777);
+
+ r = sd_bus_message_read(m, "y", &v);
+ assert_se(r > 0);
+ assert_se(v == 10);
+
r = sd_bus_message_read(m, "ba(ss)", &boolean, 3, &x, &y, &a, &b, &c, &d);
assert_se(r > 0);
assert_se(boolean);
r = sd_bus_message_read(m, "ba(ss)", &boolean, 3, &x, &y, &a, &b, &c, &d);
assert_se(r > 0);
assert_se(boolean);
assert_se(sd_bus_message_verify_type(m, 'a', "{yv}") > 0);
assert_se(sd_bus_message_verify_type(m, 'a', "{yv}") > 0);
- r = sd_bus_message_skip(m, "a{yv}");
+ r = sd_bus_message_skip(m, "a{yv}y(ty)y(yt)y");
assert_se(r >= 0);
assert_se(sd_bus_message_verify_type(m, 'b', NULL) > 0);
assert_se(r >= 0);
assert_se(sd_bus_message_verify_type(m, 'b', NULL) > 0);