Fix the warning on comparison of size_t and long

src/opustags.h

@@ -119,13 +119,16 @@ using byte_string_view = std::basic_string_view<uint8_t>;
  * \{
  */
 
+/** fclose wrapper for std::unique_ptr’s deleter. */
+void close_file(FILE*);
+
 /**
  * Smart auto-closing FILE* handle.
  *
  * It implictly converts from an already opened FILE*.
  */
-struct file : std::unique_ptr<FILE, decltype(&fclose)> {
-	file(FILE* f = nullptr) : std::unique_ptr<FILE, decltype(&fclose)>(f, &fclose) {}
+struct file : std::unique_ptr<FILE, decltype(&close_file)> {
+	file(FILE* f = nullptr) : std::unique_ptr<FILE, decltype(&close_file)>(f, &close_file) {}
 };
 
 /**

src/system.cc

@@ -29,6 +29,11 @@ ot::byte_string_view operator""_bsv(const char* data, size_t size)
 	return ot::byte_string_view(reinterpret_cast<const uint8_t*>(data), size);
 }
 
+void ot::close_file(FILE* file)
+{
+	fclose(file);
+}
+
 void ot::partial_file::open(const char* destination)
 {
 	final_name = destination;
@@ -122,7 +127,7 @@ ot::byte_string ot::slurp_binary_file(const char* filename)
 
 	byte_string content;
 	long file_size = get_file_size(f.get());
-	if (file_size == -1) {
+	if (file_size < 0) {
 		// Read the input stream block by block and resize the output byte string as needed.
 		uint8_t buffer[4096];
 		while (!feof(f.get())) {
@@ -135,7 +140,7 @@ ot::byte_string ot::slurp_binary_file(const char* filename)
 	} else {
 		// Lucky! We know the file size, so let’s slurp it at once.
 		content.resize(file_size);
-		if (fread(content.data(), 1, file_size, f.get()) < file_size)
+		if (fread(content.data(), 1, file_size, f.get()) < size_t(file_size))
 			throw status { st::standard_error,
 				       "Could not read '"s + filename + "': " + strerror(errno) + "." };
 	}