OSS-Fuzz: Add new fuzzer targets pkg Config Resolver

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

Tests/Fuzzing/CMakeLists.txt

@@ -67,6 +67,7 @@ add_fuzzer(cmExprParserFuzzer cmExprParserFuzzer.cxx)
 
 # pkg-config parser fuzzer
 add_fuzzer(cmPkgConfigParserFuzzer cmPkgConfigParserFuzzer.cxx)
+add_fuzzer(cmPkgConfigResolverFuzzer cmPkgConfigResolverFuzzer.cxx)
 
 # JSON parser fuzzer
 add_fuzzer(cmJSONParserFuzzer cmJSONParserFuzzer.cxx)

Tests/Fuzzing/cmPkgConfigResolver.dict

@@ -0,0 +1,63 @@
+# pkg-config File Dictionary
+
+# Key-value separators
+"="
+":"
+
+# Variable reference
+"${"
+"}"
+
+# Common keywords
+"Name"
+"Description"
+"Version"
+"Requires"
+"Requires.private"
+"Conflicts"
+"Libs"
+"Libs.private"
+"Cflags"
+"URL"
+
+# Common variables
+"prefix"
+"exec_prefix"
+"libdir"
+"includedir"
+"datarootdir"
+"datadir"
+"sysconfdir"
+"sharedstatedir"
+"localstatedir"
+
+# Common values
+"/usr"
+"/usr/local"
+"/usr/lib"
+"/usr/include"
+"-I"
+"-L"
+"-l"
+"-D"
+"-pthread"
+
+# Whitespace
+" "
+"\x09"
+"\x0a"
+"\x0d\x0a"
+
+# Comments
+"#"
+
+# Version operators
+">="
+"<="
+">"
+"<"
+"!="
+
+# Escapes
+"\\"
+"\\$"

Tests/Fuzzing/cmPkgConfigResolverFuzzer.cxx

@@ -0,0 +1,100 @@
+/* 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 pkg-config resolver.
+ *
+ * cmPkgConfigParserFuzzer already covers the .pc tokeniser, but it stops at
+ * the raw key/value pairs. Everything downstream of that is untested because
+ * the resolver is what drives its variable-interpolation entry points.
+ *
+ * The resolver is where the interesting work happens: recursive ${var}
+ * expansion, -I/-L/-l fragment splitting, sysroot re-rooting, and parsing
+ * "Requires:" dependency specs with version operators. .pc files come from
+ * whatever is on PKG_CONFIG_PATH, so a hostile or corrupt package drop is a
+ * realistic source of malformed input.
+ *
+ * All three strictness levels run on every input. Strictness is not chosen by
+ * the input -- Strict and Permissive reject files that BestEffort accepts, so
+ * running all three is what reaches the accept/reject paths in
+ * HasRequiredFields() and HasStrictConflicts().
+ */
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include <cm/optional>
+
+#include "cmPkgConfigParser.h"
+#include "cmPkgConfigResolver.h"
+
+static constexpr size_t kMaxInputSize = 64 * 1024;
+
+static cmPkgConfigParser ParseInput(uint8_t const* data, size_t size)
+{
+  // cmPkgConfigParser::Parse takes a non-const buffer (may modify in place)
+  std::vector<char> buffer(data, data + size);
+
+  cmPkgConfigParser parser;
+  parser.Parse(buffer.data(), buffer.size());
+  parser.Finish();
+  parser.ParseComplete();
+
+  return parser;
+}
+
+static void Consume(cmPkgConfigResolver const& resolver)
+{
+  (void)resolver.Name();
+  (void)resolver.Description();
+  (void)resolver.Version();
+
+  // Dependency specs: version operators and the spec grammar.
+  for (auto const& spec : resolver.Requires(false)) {
+    (void)cmPkgConfigResolver::VersionReqString(spec);
+    (void)cmPkgConfigResolver::CheckVersion(spec, "1.2.3");
+  }
+  (void)resolver.Requires(true);
+  (void)resolver.Conflicts();
+  (void)resolver.Provides();
+
+  // Fragment splitting and sysroot re-rooting, public and private.
+  (void)resolver.Cflags(false);
+  (void)resolver.Cflags(true);
+  (void)resolver.Libs(false);
+  (void)resolver.Libs(true);
+}
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
+{
+  if (size == 0 || size > kMaxInputSize) {
+    return 0;
+  }
+
+  cmPkgConfigEnv env;
+  env.SysrootDir = std::string("/fuzz/sysroot");
+  env.TopBuildDir = std::string("/fuzz/build");
+  env.LibDirs = std::vector<std::string>{ "/usr/lib", "/fuzz/lib" };
+  env.SysCflags = std::vector<std::string>{ "/usr/include" };
+  env.SysLibs = std::vector<std::string>{ "/usr/lib" };
+
+  std::string const pcFileDir = "/fuzz/pkgconfig";
+
+  cmPkgConfigParser const parsed = ParseInput(data, size);
+
+  if (auto strict =
+        cmPkgConfigResolver::ResolveStrict(parsed, env, pcFileDir)) {
+    Consume(*strict);
+  }
+
+  if (auto permissive =
+        cmPkgConfigResolver::ResolvePermissive(parsed, env, pcFileDir)) {
+    Consume(*permissive);
+  }
+
+  Consume(cmPkgConfigResolver::ResolveBestEffort(parsed, env, pcFileDir));
+
+  return 0;
+}