siphash24: change result argument to uint64_t

Change the "out" parameter from uint8_t[8] to uint64_t. On architectures which
enforce pointer alignment this fixes crashes when we previously cast an
unaligned array to uint64_t*, and on others this should at least improve
performance as the compiler now aligns these properly.

This also simplifies the code in most cases by getting rid of typecasts. The
only place which we can't change is struct duid's en.id, as that is _packed_
and public API, so we can't enforce alignment of the "id" field and have to
use memcpy instead.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libsystemd/sd-bus/bus-bloom.c b/src/libsystemd/sd-bus/bus-bloom.c
index 91fab90cb0..a592ff50cf 100644
--- a/src/libsystemd/sd-bus/bus-bloom.c
+++ b/src/libsystemd/sd-bus/bus-bloom.c
@@ -45,7 +45,7 @@ static void bloom_add_data(
                 const void *data,      /* Data to hash */
                 size_t n) {            /* Size of data to hash in bytes */
 
-        uint8_t h[8];
+        uint64_t h;
         uint64_t m;
         unsigned w, i, c = 0;
         unsigned hash_index;
@@ -72,11 +72,11 @@ static void bloom_add_data(
 
                 for (d = 0; d < w; d++) {
                         if (c <= 0) {
-                                siphash24(h, data, n, hash_keys[hash_index++].bytes);
+                                siphash24(&h, data, n, hash_keys[hash_index++].bytes);
                                 c += 8;
                         }
 
-                        p = (p << 8ULL) | (uint64_t) h[8 - c];
+                        p = (p << 8ULL) | (uint64_t) ((uint8_t *)&h)[8 - c];
                         c--;
                 }