hashmap: hash_funcs - make inputs unambiguous

Make sure all variable-length inputs are properly terminated or that
their length is encoded in some way. This avoids ambiguity of
adjacent inputs.

E.g., in case of a hash function taking two strings, compressing "ab"
followed by "c" is now distinct from "a" followed by "bc".

1 files changed, 5 insertions, 0 deletions

diff --git a/src/libsystemd/sd-bus/busctl.c b/src/libsystemd/sd-bus/busctl.c
index 496b9a7b4e..49c97af339 100644
--- a/src/libsystemd/sd-bus/busctl.c
+++ b/src/libsystemd/sd-bus/busctl.c
@@ -630,12 +630,17 @@ typedef struct Member {
 
 static void member_hash_func(const void *p, struct siphash *state) {
         const Member *m = p;
+        uint64_t arity = 1;
 
         assert(m);
         assert(m->type);
 
         string_hash_func(m->type, state);
 
+        arity += !!m->name + !!m->interface;
+
+        uint64_hash_func(&arity, state);
+
         if (m->name)
                 string_hash_func(m->name, state);