Write directly to FILE stream in glibc printf hooks

src/libstrongswan/printf_hook.c

@@ -86,25 +86,17 @@ static printf_hook_handler_t *printf_hooks[NUM_HANDLERS];
 static int custom_print(FILE *stream, const struct printf_info *info,
 						const void *const *args)
 {
-	int written;
-	char buf[PRINTF_BUF_LEN];
 	printf_hook_spec_t spec;
 	printf_hook_handler_t *handler = printf_hooks[SPEC_TO_INDEX(info->spec)];
 	printf_hook_data_t data = {
-		.buf = buf,
-		.buflen = sizeof(buf),
+		.stream = stream,
 	};
 
 	spec.hash = info->alt;
 	spec.minus = info->left;
 	spec.width = info->width;
 
-	written = handler->hook(&data, &spec, args);
-	if (written > 0)
-	{
-		ignore_result(fwrite(buf, 1, written, stream));
-	}
-	return written;
+	return handler->hook(&data, &spec, args);
 }
 
 /**

src/libstrongswan/printf_hook.h

@@ -46,6 +46,29 @@ enum printf_hook_argtype_t {
 	PRINTF_HOOK_ARGTYPE_POINTER = PA_POINTER,
 };
 
+/**
+ * Data to pass to a printf hook.
+ */
+struct printf_hook_data_t {
+
+	/**
+	 * Output FILE stream
+	 */
+	FILE *stream;;
+};
+
+/**
+ * Helper macro to be used in printf hook callbacks.
+ */
+#define print_in_hook(data, fmt, ...) ({\
+	int _written = fprintf(data->stream, fmt, ##__VA_ARGS__);\
+	if (_written < 0)\
+	{\
+		_written = 0;\
+	}\
+	_written;\
+})
+
 #else
 
 #include <vstr.h>
@@ -86,35 +109,6 @@ int vstr_wrapper_vasprintf(char **str, const char *format, va_list ap);
 #define vsnprintf vstr_wrapper_vsnprintf
 #define vasprintf vstr_wrapper_vasprintf
 
-#endif
-
-/**
- * Callback function type for printf hooks.
- *
- * @param data		hook data, to pass to print_in_hook()
- * @param spec		format specifier
- * @param args		arguments array
- * @return			number of characters written
- */
-typedef int (*printf_hook_function_t)(printf_hook_data_t *data,
-									  printf_hook_spec_t *spec,
-									  const void *const *args);
-
-/**
- * Helper macro to be used in printf hook callbacks.
- * buf and buflen get modified.
- */
-#define print_in_hook(data, fmt, ...) ({\
-	int _written = snprintf(data->buf, data->buflen, fmt, ##__VA_ARGS__);\
-	if (_written < 0 || _written >= data->buflen)\
-	{\
-		_written = data->buflen - 1;\
-	}\
-	data->buf += _written;\
-	data->buflen -= _written;\
-	_written;\
-})
-
 /**
  * Data to pass to a printf hook.
  */
@@ -131,6 +125,34 @@ struct printf_hook_data_t {
 	size_t buflen;
 };
 
+/**
+ * Helper macro to be used in printf hook callbacks.
+ */
+#define print_in_hook(data, fmt, ...) ({\
+	int _written = snprintf(data->buf, data->buflen, fmt, ##__VA_ARGS__);\
+	if (_written < 0 || _written >= data->buflen)\
+	{\
+		_written = data->buflen - 1;\
+	}\
+	data->buf += _written;\
+	data->buflen -= _written;\
+	_written;\
+})
+
+#endif
+
+/**
+ * Callback function type for printf hooks.
+ *
+ * @param data		hook data, to pass to print_in_hook()
+ * @param spec		format specifier
+ * @param args		arguments array
+ * @return			number of characters written
+ */
+typedef int (*printf_hook_function_t)(printf_hook_data_t *data,
+									  printf_hook_spec_t *spec,
+									  const void *const *args);
+
 /**
  * Properties of the format specifier
  */