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From 31d62b60c5b4f1baa795537da898a83e39be9dd1 Mon Sep 17 00:00:00 2001
From: Natanael Copa <ncopa@alpinelinux.org>
Date: Thu, 7 May 2015 14:41:36 +0200
Subject: [PATCH fortify-headers] fix realpath when stdlib.h is included before
limits.h
To: sin@2f30.org
If program includes stdlib.h before limits.h without _XOPEN_SOURCE,
_GNU_SOURCE or _BSD_SOURCE explicitly set, then will it always trigger
the trap with musl libc.
This is becase stdlib.h will pull in features.h which will set
_GNU_SOURCE. This means that the fortify stdlib.h will not include
limits.h but it will still trigger the fortified realpath(), but without
PATH_MAX set.
We fix this by including system stdlib.h before testing if limits.h
should be included.
Since PATH_MAX is known at compile time we can also error at compile
time, instead of compiling a broken realpath().
---
include/stdlib.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/stdlib.h b/include/stdlib.h
index 22f1f2b..6629652 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -1,12 +1,12 @@
#ifndef _FORTIFY_STDLIB_H
#define _FORTIFY_STDLIB_H
+#include_next <stdlib.h>
+
#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
#include_next <limits.h>
#endif
-#include_next <stdlib.h>
-
#if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && defined(__OPTIMIZE__) && __OPTIMIZE__ > 0
#ifdef __cplusplus
@@ -23,7 +23,7 @@ char *realpath(const char *path, char *resolved)
if (resolved) {
#ifndef PATH_MAX
- __builtin_trap();
+# error PATH_MAX unset. A fortified realpath will not work.
#else
bos = __builtin_object_size(resolved, 0);
if (PATH_MAX > bos)
--
2.4.0
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