sd-bus: introduce new match type "arg0has=" for matching arrays of strings

Previously, sd-bus inofficially already supported bus matches that
tested a string against an array of strings ("as"). This was done via an
enhanced way to interpret "arg0=" matches. This is problematic however,
since clients have no way to determine if their respective
implementation understood strv matches or not, thus allowing invalid
matches to be installed without a way to detect that.

This patch changes the logic to only allow such matches with a new
"arg0has=" syntax. This has the benefit that non-conforming
implementations will return a parse error and a client application may
thus efficiently detect support for the match type.

Matches of this type are useful for "udev"-like systems that "tag" objects
with a number of strings, and clients need to be able to match against
any of these "tags".

The name "has" takes inspiration from Python's ".has_key()" construct.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/libsystemd/sd-bus/test-bus-match.c b/src/libsystemd/sd-bus/test-bus-match.c
index f659ba3124..e29975db44 100644
--- a/src/libsystemd/sd-bus/test-bus-match.c
+++ b/src/libsystemd/sd-bus/test-bus-match.c
@@ -114,10 +114,10 @@ int main(int argc, char *argv[]) {
         assert_se(match_add(slots, &root, "arg1='two'", 12) >= 0);
         assert_se(match_add(slots, &root, "member='waldo',arg2path='/prefix/'", 13) >= 0);
         assert_se(match_add(slots, &root, "member=waldo,path='/foo/bar',arg3namespace='prefix'", 14) >= 0);
-        assert_se(match_add(slots, &root, "arg4='pi'", 15) >= 0);
-        assert_se(match_add(slots, &root, "arg4='pa'", 16) >= 0);
-        assert_se(match_add(slots, &root, "arg4='po'", 17) >= 0);
-        assert_se(match_add(slots, &root, "arg4='pu'", 18) >= 0);
+        assert_se(match_add(slots, &root, "arg4has='pi'", 15) >= 0);
+        assert_se(match_add(slots, &root, "arg4has='pa'", 16) >= 0);
+        assert_se(match_add(slots, &root, "arg4has='po'", 17) >= 0);
+        assert_se(match_add(slots, &root, "arg4='pi'", 18) >= 0);
 
         bus_match_dump(&root, 0);