[libc-commits] [libc] [libc] Add a differential fuzzer for inet_aton (PR #200341)

[Jeff Bailey via libc-commits]

================
@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Differential fuzz test for llvm-libc inet_aton implementation.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/arpa/inet/inet_aton.h"
+#include <arpa/inet.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  if (size == 0 || data[size - 1] != '\0')
+    return -1;
+
+  struct in_addr ref_addr = {};
+  struct in_addr impl_addr = {};
+  int ref = ::inet_aton(reinterpret_cast<const char *>(data), &ref_addr);
+  int impl = LIBC_NAMESPACE::inet_aton(reinterpret_cast<const char *>(data),
+                                       &impl_addr);
+
+  if (ref != impl) {
+    fprintf(stderr,
+            "Different result (reference: %d, implementation: %d) for \"%s\"\n",
+            ref, impl, data);
----------------
kaladron wrote:

data here should be cast to const char* as you did above for impl, and it's needed below as well.

I suggest just making a new variable with that once at the top and using it throughout.

https://github.com/llvm/llvm-project/pull/200341