From eb3b1ec5f1ccdeccae237fa8c8662e795bb7fad7 Mon Sep 17 00:00:00 2001
From: Jerzi Kaminsky <JerziKaminsky@users.noreply.github.com>
Date: Sun, 16 Apr 2017 10:30:17 +0300
Subject: [PATCH] Fix variadic forwarding in sway_assert

_sway_assert is a variadic function which tries
to delegate to another variadic function. This
requires a vprintf-style variant of the delegate.

https://stackoverflow.com/a/150616
---
 common/log.c  | 15 ++++++++++-----
 include/log.h |  3 +++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/common/log.c b/common/log.c
index c3809c69..23b756eb 100644
--- a/common/log.c
+++ b/common/log.c
@@ -63,7 +63,8 @@ void sway_abort(const char *format, ...) {
 	sway_terminate(EXIT_FAILURE);
 }
 
-void _sway_log(const char *filename, int line, log_importance_t verbosity, const char* format, ...) {
+void _sway_vlog(const char *filename, int line, log_importance_t verbosity,
+		const char *format, va_list args) {
 	if (verbosity <= v) {
 		// prefix the time to the log message
 		static struct tm result;
@@ -99,10 +100,7 @@ void _sway_log(const char *filename, int line, log_importance_t verbosity, const
 			fprintf(stderr, "[%s:%d] ", file, line);
 		}
 
-		va_list args;
-		va_start(args, format);
 		vfprintf(stderr, format, args);
-		va_end(args);
 
 		if (colored && isatty(STDERR_FILENO)) {
 			fprintf(stderr, "\x1B[0m");
@@ -111,6 +109,13 @@ void _sway_log(const char *filename, int line, log_importance_t verbosity, const
 	}
 }
 
+void _sway_log(const char *filename, int line, log_importance_t verbosity, const char* format, ...) {
+	va_list args;
+	va_start(args, format);
+	_sway_vlog(filename, line, verbosity, format, args);
+	va_end(args);
+}
+
 void sway_log_errno(log_importance_t verbosity, char* format, ...) {
 	if (verbosity <= v) {
 		unsigned int c = verbosity;
@@ -144,7 +149,7 @@ bool _sway_assert(bool condition, const char* format, ...) {
 
 	va_list args;
 	va_start(args, format);
-	sway_log(L_ERROR, format, args);
+	sway_vlog(L_ERROR, format, args);
 	va_end(args);
 
 #ifndef NDEBUG
diff --git a/include/log.h b/include/log.h
index 2c4150e4..60b3763b 100644
--- a/include/log.h
+++ b/include/log.h
@@ -28,6 +28,9 @@ void _sway_log(const char *filename, int line, log_importance_t verbosity, const
 #define sway_log(VERBOSITY, FMT, ...) \
 	_sway_log(__FILE__, __LINE__, VERBOSITY, FMT, ##__VA_ARGS__)
 
+#define sway_vlog(VERBOSITY, FMT, VA_ARGS) \
+    _sway_vlog(__FILE__, __LINE__, VERBOSITY, FMT, VA_ARGS)
+
 void error_handler(int sig);
 
 #endif