fix static analyzer warnings

they are suspicious that some tests on unsigned values might wrap around. They should not, but let's write these branches differently to also cover these cases.
Cyan4973 · Dec 28, 2024 · 4dd799c · 4dd799c
1 parent bca2d27
commit 4dd799c
Showing 1 changed file with 29 additions and 25 deletions.
diff --git a/xxhash.h b/xxhash.h
@@ -3236,27 +3236,29 @@ XXH32_update(XXH32_state_t* state, const void* input, size_t len)
         return XXH_OK;
     }
 
-    {   const xxh_u8* xinput = (const xxh_u8*)input;
-        const xxh_u8* const bEnd = xinput + len;
+    state->total_len_32 += (XXH32_hash_t)len;
+    state->large_len |= (XXH32_hash_t)((len>=16) | (state->total_len_32>=16));
 
-        state->total_len_32 += (XXH32_hash_t)len;
-        state->large_len |= (XXH32_hash_t)((len>=16) | (state->total_len_32>=16));
+    XXH_ASSERT(state->bufferedSize < sizeof(state->buffer));
+    if (len < sizeof(state->buffer) - state->bufferedSize)  {   /* fill in tmp buffer */
+        XXH_memcpy(state->buffer + state->bufferedSize, input, len);
+        state->bufferedSize += (XXH32_hash_t)len;
+        return XXH_OK;
+    }
 
-        if (len < sizeof(state->buffer) - state->bufferedSize)  {   /* fill in tmp buffer */
-            XXH_memcpy(state->buffer + state->bufferedSize, xinput, len);
-            state->bufferedSize += (XXH32_hash_t)len;
-            return XXH_OK;
-        }
+    {   const xxh_u8* xinput = (const xxh_u8*)input;
+        const xxh_u8* const bEnd = xinput + len;
 
-        if (state->bufferedSize) {   /* tmp buffer is full */
+        if (state->bufferedSize) {   /* non-empty buffer: complete first */
             XXH_memcpy(state->buffer + state->bufferedSize, xinput, sizeof(state->buffer) - state->bufferedSize);
-            /* Process the tmp buffer */
-            (void)XXH32_consumeLong(state->acc, state->buffer, sizeof(state->buffer), XXH_aligned);
             xinput += sizeof(state->buffer) - state->bufferedSize;
+            /* then process one round */
+            (void)XXH32_consumeLong(state->acc, state->buffer, sizeof(state->buffer), XXH_aligned);
             state->bufferedSize = 0;
         }
 
-        if (xinput + sizeof(state->buffer) <= bEnd) {
+        XXH_ASSERT(xinput <= bEnd);
+        if ((size_t)(bEnd - xinput) >= sizeof(state->buffer)) {
             /* Process the remaining data */
             xinput = XXH32_consumeLong(state->acc, xinput, (size_t)(bEnd - xinput), XXH_unaligned);
         }
@@ -3730,26 +3732,28 @@ XXH64_update (XXH_NOESCAPE XXH64_state_t* state, XXH_NOESCAPE const void* input,
         return XXH_OK;
     }
 
-    {   const xxh_u8* xinput = (const xxh_u8*)input;
-        const xxh_u8* const bEnd = xinput + len;
+    state->total_len += len;
 
-        state->total_len += (XXH32_hash_t)len;
+    XXH_ASSERT(state->bufferedSize <= sizeof(state->buffer));
+    if (len < sizeof(state->buffer) - state->bufferedSize)  {   /* fill in tmp buffer */
+        XXH_memcpy(state->buffer + state->bufferedSize, input, len);
+        state->bufferedSize += (XXH32_hash_t)len;
+        return XXH_OK;
+    }
 
-        if (len < sizeof(state->buffer) - state->bufferedSize)  {   /* fill in tmp buffer */
-            XXH_memcpy(state->buffer + state->bufferedSize, xinput, len);
-            state->bufferedSize += (XXH32_hash_t)len;
-            return XXH_OK;
-        }
+    {   const xxh_u8* xinput = (const xxh_u8*)input;
+        const xxh_u8* const bEnd = xinput + len;
 
-        if (state->bufferedSize) {   /* tmp buffer is full */
+        if (state->bufferedSize) {   /* non-empty buffer => complete first */
             XXH_memcpy(state->buffer + state->bufferedSize, xinput, sizeof(state->buffer) - state->bufferedSize);
-            /* Process the tmp buffer */
-            (void)XXH64_consumeLong(state->acc, state->buffer, sizeof(state->buffer), XXH_aligned);
             xinput += sizeof(state->buffer) - state->bufferedSize;
+            /* and process one round */
+            (void)XXH64_consumeLong(state->acc, state->buffer, sizeof(state->buffer), XXH_aligned);
             state->bufferedSize = 0;
         }
 
-        if (xinput + sizeof(state->buffer) <= bEnd) {
+        XXH_ASSERT(xinput <= bEnd);
+        if ((size_t)(bEnd - xinput) >= sizeof(state->buffer)) {
             /* Process the remaining data */
             xinput = XXH64_consumeLong(state->acc, xinput, (size_t)(bEnd - xinput), XXH_unaligned);
         }