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, 2 insertions, 0 deletions

diff --git a/src/libsystemd/sd-bus/bus-match.h b/src/libsystemd/sd-bus/bus-match.h
index 56516be9fa..53ee0463ca 100644
--- a/src/libsystemd/sd-bus/bus-match.h
+++ b/src/libsystemd/sd-bus/bus-match.h
@@ -44,6 +44,8 @@ enum bus_match_node_type {
         BUS_MATCH_ARG_PATH_LAST = BUS_MATCH_ARG_PATH + 63,
         BUS_MATCH_ARG_NAMESPACE,
         BUS_MATCH_ARG_NAMESPACE_LAST = BUS_MATCH_ARG_NAMESPACE + 63,
+        BUS_MATCH_ARG_HAS,
+        BUS_MATCH_ARG_HAS_LAST = BUS_MATCH_ARG_HAS + 63,
         _BUS_MATCH_NODE_TYPE_MAX,
         _BUS_MATCH_NODE_TYPE_INVALID = -1
 };