Minor cleanup of FileSaver

include/flatbuffers/file_manager.h

@@ -18,6 +18,7 @@
 #define FLATBUFFERS_FILE_MANAGER_H_
 
 #include <cstddef>
+#include <memory>
 #include <set>
 #include <string>
 
@@ -48,22 +49,8 @@ class FileSaver {
   FileSaver& operator=(FileSaver&&) = default;
 };
 
-class RealFileSaver final : public FileSaver {
- public:
-  bool SaveFile(const char* name, const char* buf, size_t len,
-                bool binary) final;
-};
-
-class FileNameSaver final : public FileSaver {
- public:
-  bool SaveFile(const char* name, const char* buf, size_t len,
-                bool binary) final;
-
-  void Finish() final;
-
- private:
-  std::set<std::string> file_names_{};
-};
+std::unique_ptr<FileSaver> CreateFileSaver();
+std::unique_ptr<FileSaver> CreateFileNameCollector();
 
 }  // namespace flatbuffers
 

src/file_manager.cpp

@@ -22,12 +22,26 @@
 
 namespace flatbuffers {
 
-bool RealFileSaver::SaveFile(const char* name, const char* buf, size_t len,
-                             bool binary) {
-  std::ofstream ofs(name, binary ? std::ofstream::binary : std::ofstream::out);
-  if (!ofs.is_open()) return false;
-  ofs.write(buf, len);
-  return !ofs.bad();
+class RealFileSaver final : public FileSaver {
+ public:
+  bool SaveFile(const char* name, const char* buf, size_t len,
+                bool binary) final {
+    std::ofstream ofs{name,
+                      binary ? std::ofstream::binary : std::ofstream::out};
+
+    if (!ofs.is_open()) {
+      return false;
+    }
+
+    ofs.write(buf, len);
+
+    return !ofs.bad();
+  }
+};
+
+std::unique_ptr<FileSaver> CreateFileSaver() {
+  // compiler limitations mean we can't use std::make_unique
+  return std::unique_ptr<FileSaver>{new RealFileSaver()};
 }
 
 }  // namespace flatbuffers

src/file_name_manager.cpp

@@ -21,24 +21,35 @@
 
 namespace flatbuffers {
 
-bool FileNameSaver::SaveFile(const char* name, const char* buf, size_t len,
-                             bool binary) {
-  (void)buf;
-  (void)len;
-  (void)binary;
+class FileNameSaver final : public FileSaver {
+ public:
+  bool SaveFile(const char* name, const char* buf, size_t len,
+                bool binary) final {
+    (void)buf;
+    (void)len;
+    (void)binary;
+
+    std::ignore = file_names_.insert(name);
+
+    // we want to simulate always successful save
+    return true;
+  }
 
-  std::ignore = file_names_.insert(name);
+  void Finish() final {
+    for (const auto& file_name : file_names_) {
+      // Just print the file names to standard output.
+      // No actual file is created.
+      std::cout << file_name << "\n";
+    }
+  }
 
-  // we want to simulate always successful save
-  return true;
-}
+ private:
+  std::set<std::string> file_names_{};
+};
 
-void FileNameSaver::Finish() {
-  for (const auto& file_name : file_names_) {
-    // Just print the file names to standard output.
-    // No actual file is created.
-    std::cout << file_name << "\n";
-  }
+std::unique_ptr<FileSaver> CreateFileNameCollector() {
+  // compiler limitations mean we can't use std::make_unique
+  return std::unique_ptr<FileSaver>{new FileNameSaver()};
 }
 
 }  // namespace flatbuffers

src/flatc_main.cpp

@@ -187,9 +187,9 @@ int main(int argc, const char* argv[]) {
   // this exists here to ensure file_saver outlives the compilation process
   std::unique_ptr<flatbuffers::FileSaver> file_saver;
   if (options.file_names_only) {
-    file_saver.reset(new flatbuffers::FileNameSaver{});
+    file_saver = flatbuffers::CreateFileNameCollector();
   } else {
-    file_saver.reset(new flatbuffers::RealFileSaver{});
+    file_saver = flatbuffers::CreateFileSaver();
   }
 
   options.opts.file_saver = file_saver.get();

src/idl_gen_binary.cpp

@@ -41,6 +41,9 @@ static std::string BinaryFileName(const Parser& parser, const std::string& path,
 
 static bool GenerateBinary(const Parser& parser, const std::string& path,
                            const std::string& file_name) {
+  // sanity check we have a file saver
+  if (!parser.opts.file_saver) return false;
+
   if (parser.opts.use_flexbuffers) {
     auto data_vec = parser.flex_builder_.GetBuffer();
     auto data_ptr = reinterpret_cast<char*>(data(data_vec));

tests/fuzzer/flatbuffers_codegen_fuzzer.cc

@@ -90,6 +90,10 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
       (flags & flags_skip_unexpected_fields_in_json);
   opts.allow_non_utf8 = (flags & flags_allow_non_utf8);
 
+  // make sure we have a file saver
+  auto saver = flatbuffers::CreateFileSaver();
+  opts.file_saver = saver.get();
+
   flatbuffers::Parser parser(opts);
 
   // Guarantee 0-termination in the input.