[PATCH] fix strdupa evaulating expression twice

[Noam Meltzer <tsnoam@gmail.com>]

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From bf23b7b8fd39eaca6a05173eaf543e1bce3319ab Mon Sep 17 00:00:00 2001
From: Noam Meltzer <tsnoam@gmail.com>
Date: Sun, 28 Aug 2016 13:53:24 +0300
Subject: [PATCH] fix strdupa evaulating expression twice

calling strdupa with va_arg as its expression caused unexpected
behaviour. now the expression is evaulated only once.
---
 include/string.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/string.h b/include/string.h
index ff9badb..976faaf 100644
--- a/include/string.h
+++ b/include/string.h
@@ -85,7 +85,10 @@ size_t strlcpy (char *, const char *, size_t);
 #endif
 
 #ifdef _GNU_SOURCE
-#define	strdupa(x)	strcpy(alloca(strlen(x)+1),x)
+#define	strdupa(x) (__extension__ ({ \
+		const char *__xval = x; \
+		strcpy(alloca(strlen(__xval)+1),__xval); \
+	}))
 int strverscmp (const char *, const char *);
 int strcasecmp_l (const char *, const char *, locale_t);
 int strncasecmp_l (const char *, const char *, size_t, locale_t);
-- 
2.7.4