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From: Christian Neukirchen <>
Subject: compat_vasprintf.c: use va_copy
Date: Fri, 20 Mar 2015 15:36:49 +0100	[thread overview]
Message-ID: <> (raw)


When building CVS HEAD on Linux x86_64/glibc, the vasprintf check
fails when -D_GNU_SOURCE is not passed, and mdocml falls back to
compat_vasprintf.c.  This version of vasprintf.c segfaults on glibc,
because the same va_list is used twice.  Probably affects other
architectures too.

The solution is to use va_copy to get a second va_list.

--- compat_vasprintf.c
+++ compat_vasprintf.c
@@ -38,9 +38,13 @@ vasprintf(char **ret, const char *format, va_list ap)
 	char	 buf[2];
 	int	 sz;
+	va_list	 ap2;
-	if ((sz = vsnprintf(buf, sizeof(buf), format, ap)) != -1 &&
-	    (*ret = malloc(sz + 1)) != NULL) {
+	va_copy(ap2, ap);
+	sz = vsnprintf(buf, sizeof(buf), format, ap2);
+	va_end(ap2);
+	if (sz != -1 && (*ret = malloc(sz + 1)) != NULL) {
 		if (vsnprintf(*ret, sz + 1, format, ap) == sz)

Christian Neukirchen  <>
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             reply	other threads:[~2015-03-20 14:36 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-20 14:36 Christian Neukirchen [this message]
2015-03-20 15:45 ` Ingo Schwarze

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