hashmap: refactor hash_func

All our hash functions are based on siphash24(), factor out
siphash_init() and siphash24_finalize() and pass the siphash
state to the hash functions rather than the hash key.

This simplifies the hash functions, and in particular makes
composition simpler as calling siphash24_compress() repeatedly
on separate chunks of input has the same effect as first
concatenating the input and then calling siphash23_compress()
on the result.

2 files changed, 8 insertions, 22 deletions

diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c
index 1d061cb9cf..728f20447a 100644
--- a/src/libsystemd/sd-bus/bus-objects.c
+++ b/src/libsystemd/sd-bus/bus-objects.c
@@ -1578,25 +1578,14 @@ _public_ int sd_bus_add_fallback(
         return bus_add_object(bus, slot, true, prefix, callback, userdata);
 }
 
-static unsigned long vtable_member_hash_func(const void *a, const uint8_t hash_key[HASH_KEY_SIZE]) {
+static void vtable_member_hash_func(const void *a, struct siphash *state) {
         const struct vtable_member *m = a;
-        uint8_t hash_key2[HASH_KEY_SIZE];
-        unsigned long ret;
 
         assert(m);
 
-        ret = string_hash_func(m->path, hash_key);
-
-        /* Use a slightly different hash key for the interface */
-        memcpy(hash_key2, hash_key, HASH_KEY_SIZE);
-        hash_key2[0]++;
-        ret ^= string_hash_func(m->interface, hash_key2);
-
-        /* And an even different one for the  member */
-        hash_key2[0]++;
-        ret ^= string_hash_func(m->member, hash_key2);
-
-        return ret;
+        string_hash_func(m->path, state);
+        string_hash_func(m->interface, state);
+        string_hash_func(m->member, state);
 }
 
 static int vtable_member_compare_func(const void *a, const void *b) {
diff --git a/src/libsystemd/sd-bus/busctl.c b/src/libsystemd/sd-bus/busctl.c
index ab8816942c..496b9a7b4e 100644
--- a/src/libsystemd/sd-bus/busctl.c
+++ b/src/libsystemd/sd-bus/busctl.c
@@ -628,22 +628,19 @@ typedef struct Member {
         uint64_t flags;
 } Member;
 
-static unsigned long member_hash_func(const void *p, const uint8_t hash_key[]) {
+static void member_hash_func(const void *p, struct siphash *state) {
         const Member *m = p;
-        unsigned long ul;
 
         assert(m);
         assert(m->type);
 
-        ul = string_hash_func(m->type, hash_key);
+        string_hash_func(m->type, state);
 
         if (m->name)
-                ul ^= string_hash_func(m->name, hash_key);
+                string_hash_func(m->name, state);
 
         if (m->interface)
-                ul ^= string_hash_func(m->interface, hash_key);
-
-        return ul;
+                string_hash_func(m->interface, state);
 }
 
 static int member_compare_func(const void *a, const void *b) {