Adding an overload of ReadFilesFromDirectory that takes in a filename…

fuzztest/fuzztest_macros.cc

@@ -87,6 +87,35 @@ std::vector<std::tuple<std::string>> ReadFilesFromDirectory(
   return out;
 }
 
+std::vector<std::tuple<std::string>> ReadFilesFromDirectory(
+    std::string_view dir, std::string_view filename_pattern) {
+  std::vector<std::tuple<std::string>> out;
+  const std::filesystem::path fs_dir(dir);
+  std::regex regex_pattern(filename_pattern.data());
+  if (!std::filesystem::is_directory(fs_dir)) return out;
+  for (const auto& entry :
+       std::filesystem::recursive_directory_iterator(fs_dir)) {
+    if (std::filesystem::is_directory(entry)) continue;
+
+    // Check if the file matches regex_pattern
+    if (!std::regex_match(entry.path().string(), regex_pattern)) continue;
+
+    std::ifstream stream(entry.path().string());
+    if (!stream.good()) {
+      // Using stderr instead of GetStderr() to avoid
+      // initialization-order-fiasco when reading files at static init time with
+      // `.WithSeeds(fuzztest::ReadFilesFromDirectory(...))`.
+      absl::FPrintF(stderr, "[!] %s:%d: Error reading %s: (%d) %s\n", __FILE__,
+                    __LINE__, entry.path().string(), errno, strerror(errno));
+      continue;
+    }
+    std::stringstream buffer;
+    buffer << stream.rdbuf();
+    out.push_back({buffer.str()});
+  }
+  return out;
+}
+
 absl::StatusOr<std::vector<std::string>> ParseDictionary(
     absl::string_view text) {
   std::vector<std::string> parsed_entries;

fuzztest/fuzztest_macros.h

@@ -16,6 +16,7 @@
 #define FUZZTEST_FUZZTEST_FUZZTEST_MACROS_H_
 
 #include <cstdint>
+#include <regex>
 #include <string>
 #include <string_view>
 #include <tuple>
@@ -127,6 +128,11 @@ namespace fuzztest {
 std::vector<std::tuple<std::string>> ReadFilesFromDirectory(
     std::string_view dir);
 
+// Overload of ReadFilesFromDirectory() that filters files by their names using regex.
+// Example: ReadFilesFromDirectory(dir, ".*\\.der$") to read only .der files.
+std::vector<std::tuple<std::string>> ReadFilesFromDirectory(
+    std::string_view dir, std::string_view filename_pattern);
+
 // Returns parsed dictionary entries from fuzzer dictionary definition in the
 // format specified at https://llvm.org/docs/LibFuzzer.html#dictionaries.
 // If dictionary is in wrong format, return error status.