libc/fuzzing/string/bcmp_fuzz.cpp

   1 //===-- bcmp_fuzz.cpp ---------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// Fuzzing test for llvm-libc bcmp implementation.
  10 ///
  11 //===----------------------------------------------------------------------===//
  12 #include "src/strings/bcmp.h"
  13 #include <stddef.h>
  14 #include <stdint.h>
  15 #include <stdio.h>
  16 #include <string.h>
  17
  18 static int reference_bcmp(const void *pa, const void *pb, size_t count)
  19     __attribute__((no_builtin)) {
  20   const auto *a = reinterpret_cast<const unsigned char *>(pa);
  21   const auto *b = reinterpret_cast<const unsigned char *>(pb);
  22   for (size_t i = 0; i < count; ++i, ++a, ++b)
  23     if (*a != *b)
  24       return 1;
  25   return 0;
  26 }
  27
  28 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
  29   const auto normalize = [](int value) -> int {
  30     if (value == 0)
  31       return 0;
  32     return 1;
  33   };
  34   // We ignore the last byte is size is odd.
  35   const auto count = size / 2;
  36   const char *a = reinterpret_cast<const char *>(data);
  37   const char *b = reinterpret_cast<const char *>(data) + count;
  38   const int actual = LIBC_NAMESPACE::bcmp(a, b, count);
  39   const int reference = reference_bcmp(a, b, count);
  40   if (normalize(actual) == normalize(reference))
  41     return 0;
  42   const auto print = [](const char *msg, const char *buffer, size_t size) {
  43     printf("%s\"", msg);
  44     for (size_t i = 0; i < size; ++i)
  45       printf("\\x%02x", (uint8_t)buffer[i]);
  46     printf("\"\n");
  47   };
  48   printf("count    : %zu\n", count);
  49   print("a        : ", a, count);
  50   print("b        : ", b, count);
  51   printf("expected : %d\n", reference);
  52   printf("actual   : %d\n", actual);
  53   __builtin_trap();
  54 }