1 files changed, 35 insertions, 21 deletions

diff --git a/tools/backlight_helper.c b/tools/backlight_helper.c
index 24958ec6..8b2667dc 100644
--- a/tools/backlight_helper.c
+++ b/tools/backlight_helper.c
@@ -1,43 +1,57 @@
 #include <stdio.h>
 #include <string.h>
+#include <stdarg.h>
+#include <stdlib.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#define DBG 0
+
+#if defined(__GNUC__) && (__GNUC__ > 3)
+__attribute__((format(printf, 1, 2), noreturn))
+#endif
+static void die(const char *format, ...)
+{
+	if (DBG) {
+		va_list args;
+
+		va_start(args, format);
+		vfprintf(stderr, format, args);
+		va_end(args);
+	}
+
+	exit(1);
+}
+
 int main(int argc, char *argv[])
 {
 	struct stat st;
 	char buf[1024];
 	int len, fd;
 
-	if (argc != 2) {
-		fprintf(stderr, "Usage: %s <iface>\n", argv[0]);
-		return 1;
-	}
+	if (argc != 2)
+		die("Usage: xf86-video-intel-backlight-helper <iface>\n");
+
+	if (strchr(argv[1], '/') != NULL)
+		die("Invalid interface '%s': contains '/'\n", argv[1]);
+
+	if (snprintf(buf, sizeof(buf),
+		     "/sys/class/backlight/%s/brightness",
+		     argv[1]) >= sizeof(buf))
+		die("Invalid interface '%s': name too long\n", argv[1]);
 
-	if (strchr(argv[1], '/') != NULL) {
-		fprintf(stderr, "Invalid interface name\n");
-		return 1;
-	}
-	if (snprintf(buf, sizeof(buf), "/sys/class/backlight/%s/brightness",
-		argv[1]) >= sizeof(buf)) {
-		fprintf(stderr, "Interface name is too long\n");
-		return 1;
-	}
 	fd = open(buf, O_RDWR);
-	if (fd < 0 || fstat(fd, &st) || major(st.st_dev)) {
-		fprintf(stderr, "Cannot access backlight interface '%s'\n", argv[1]);
-		return 1;
-	}
+	if (fd < 0 || fstat(fd, &st) || major(st.st_dev))
+		die("Invalid interface '%s': unknown backlight file\n", argv[1]);
 
 	while (fgets(buf, sizeof(buf), stdin)) {
 		len = strlen(buf);
-		if (write(fd, buf, len) != len) {
-			fprintf(stderr, "Failed to update backlight interface '%s'\n", argv[1]);
-			return 2;
-		}
+		if (write(fd, buf, len) != len)
+			die("Failed to update backlight interface '%s': errno=%d\n", argv[1], errno);
 	}
 
 	return 0;