From c79f3527498974c328404ed6807f9aaa5608832e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>
Date: Fri, 29 May 2015 03:11:59 +0100
Subject: linkat: avoid OS X 10.10 trailing slash with symlink bug

On Darwin 14.3.0 linkat(,"path1",,"dangling_symlink/",)
causes the symlink to be dereferenced, and if it points
to a non existent file, that file will be created as
a hard link to "path1".
This fixes a test failure in test-linkat.c.

* m4/linkat.m4 (gl_FUNC_LINKAT): Augment the test with
this case.  The existing workaround in linkat.c for
trailing slash issues, suffices for this case.
* doc/posix-functions/linkat.texi: Add OS X 10.10 to
the list of platforms with trailing slash issues.
---
 m4/linkat.m4 | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

(limited to 'm4')

diff --git a/m4/linkat.m4 b/m4/linkat.m4
index 567cb5dcaa..03cf23a2e4 100644
--- a/m4/linkat.m4
+++ b/m4/linkat.m4
@@ -52,7 +52,7 @@ AC_DEFUN([gl_FUNC_LINKAT],
 
     AC_CACHE_CHECK([whether linkat handles trailing slash correctly],
       [gl_cv_func_linkat_slash],
-      [rm -rf conftest.a conftest.b conftest.c conftest.d
+      [rm -rf conftest.a conftest.b conftest.c conftest.d conftest.e conftest.s
        AC_RUN_IFELSE(
          [AC_LANG_PROGRAM(
             [[#include <unistd.h>
@@ -83,6 +83,16 @@ AC_DEFUN([gl_FUNC_LINKAT],
               if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.d/",
                           AT_SYMLINK_FOLLOW) == 0)
                 result |= 8;
+
+              /* On OS X 10.10 a trailing "/" will cause the second path to be
+                 dereferenced, and thus will succeed on a dangling symlink.  */
+              if (symlink ("conftest.e", "conftest.s") == 0)
+                {
+                  if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.s/",
+                      AT_SYMLINK_FOLLOW) == 0)
+                    result |= 16;
+                }
+
               return result;
             ]])],
          [gl_cv_func_linkat_slash=yes],
@@ -93,7 +103,7 @@ AC_DEFUN([gl_FUNC_LINKAT],
             *)      gl_cv_func_linkat_slash="guessing no";;
           esac
          ])
-       rm -rf conftest.a conftest.b conftest.c conftest.d])
+       rm -rf conftest.a conftest.b conftest.c conftest.d conftest.e conftest.s])
     case "$gl_cv_func_linkat_slash" in
       *yes) gl_linkat_slash_bug=0 ;;
       *)    gl_linkat_slash_bug=1 ;;
-- 
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