Tests/Fuzzing: Add cmGccDepfileFuzzer

Fuzz the CMake GCC-style dependency file parser.
Tests parsing of .d files from compiler output.

Tests/Fuzzing/CMakeLists.txt

@@ -70,3 +70,6 @@ add_fuzzer(cmPkgConfigParserFuzzer cmPkgConfigParserFuzzer.cxx)
 
 # JSON parser fuzzer
 add_fuzzer(cmJSONParserFuzzer cmJSONParserFuzzer.cxx)
+
+# GCC dependency file fuzzer
+add_fuzzer(cmGccDepfileFuzzer cmGccDepfileFuzzer.cxx)

Tests/Fuzzing/cmGccDepfile.dict

@@ -0,0 +1,45 @@
+# GCC depfile dictionary
+
+# Target separator
+":"
+
+# Dependency continuation
+"\\"
+
+# Whitespace
+" "
+"\x09"
+"\x0a"
+
+# Common file extensions
+".o"
+".obj"
+".d"
+".cpp"
+".c"
+".h"
+".hpp"
+".hxx"
+
+# Escape sequences
+"\\ "
+"\\#"
+"\\:"
+
+# Special characters
+"#"
+"$"
+
+# Common paths
+"/usr/include/"
+"/usr/local/include/"
+"../include/"
+"./src/"
+
+# Common headers
+"stdio.h"
+"stdlib.h"
+"string.h"
+"iostream"
+"vector"
+"string"

Tests/Fuzzing/cmGccDepfileFuzzer.cxx

@@ -0,0 +1,76 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file LICENSE.rst or https://cmake.org/licensing for details.  */
+
+/*
+ * Fuzzer for CMake's GCC dependency file parser
+ *
+ * GCC generates .d files with make-style dependencies.
+ * This fuzzer tests parsing of these files.
+ */
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <string>
+
+#include <unistd.h>
+
+#include "cmGccDepfileReader.h"
+#include "cmSystemTools.h"
+
+static constexpr size_t kMaxInputSize = 256 * 1024;
+static std::string g_testDir;
+
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv)
+{
+  (void)argc;
+  (void)argv;
+
+  char tmpl[] = "/tmp/cmake_fuzz_depfile_XXXXXX";
+  char* dir = mkdtemp(tmpl);
+  if (dir) {
+    g_testDir = dir;
+  } else {
+    g_testDir = "/tmp/cmake_fuzz_depfile";
+    cmSystemTools::MakeDirectory(g_testDir);
+  }
+
+  return 0;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
+{
+  if (size == 0 || size > kMaxInputSize) {
+    return 0;
+  }
+
+  // Write input to temp file
+  std::string depFile = g_testDir + "/test.d";
+  {
+    FILE* fp = fopen(depFile.c_str(), "wb");
+    if (!fp)
+      return 0;
+    fwrite(data, 1, size, fp);
+    fclose(fp);
+  }
+
+  // Parse the depfile
+  auto result = cmReadGccDepfile(depFile.c_str());
+
+  // Examine results if parsing succeeded
+  if (result) {
+    for (auto const& entry : *result) {
+      for (auto const& rule : entry.rules) {
+        (void)rule;
+      }
+      for (auto const& path : entry.paths) {
+        (void)path;
+      }
+    }
+  }
+
+  // Clean up
+  unlink(depFile.c_str());
+
+  return 0;
+}