From 28c49d6eae7fedc796e801d6595ed65dbe8bb2cb Mon Sep 17 00:00:00 2001
From: Laslo Hunhold <dev@frign.de>
Date: Thu, 17 May 2018 23:23:28 +0200
Subject: Properly handle *snprintf() errors

Posix guarantees that the resulting string is null-terminated, even if
we have an overflow. Instead of doing what has already been done,
properly warn when there has been an error or overflow, so the user can
do something about it.
---
 util.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

(limited to 'util.c')

diff --git a/util.c b/util.c
index 8808aba..6113049 100644
--- a/util.c
+++ b/util.c
@@ -10,15 +10,15 @@ const char *
 bprintf(const char *fmt, ...)
 {
 	va_list ap;
-	size_t len;
+	int ret;
 
 	va_start(ap, fmt);
-	len = vsnprintf(buf, sizeof(buf) - 1, fmt, ap);
-	va_end(ap);
-
-	if (len >= sizeof(buf)) {
-		buf[sizeof(buf)-1] = '\0';
+	if ((ret = vsnprintf(buf, sizeof(buf), fmt, ap)) < 0) {
+		fprintf(stderr, "vsnprintf: %s\n", strerror(errno));
+	} else if ((size_t)ret >= sizeof(buf)) {
+		fprintf(stderr, "vsnprintf: Output truncated\n");
 	}
+	va_end(ap);
 
 	return buf;
 }
-- 
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