X-Git-Url: https://git.cworth.org/git?p=tar;a=blobdiff_plain;f=m4%2Freadlink.m4;h=36cd41f9b8e1b7ae49a36ed9d6fb99eb97e7e2dc;hp=ff3f1f5876f1947ea35afa4c43c941ef3975bdd9;hb=22f1eb8bc17e5be72dd23d42d6aaa60196ac22e6;hpb=00fa13ff3f2d5b6e2a94c5e948c38616ff7ad37a

diff --git a/m4/readlink.m4 b/m4/readlink.m4
index ff3f1f5..36cd41f 100644
--- a/m4/readlink.m4
+++ b/m4/readlink.m4
@@ -1,5 +1,5 @@
-# readlink.m4 serial 5
-dnl Copyright (C) 2003, 2007, 2009 Free Software Foundation, Inc.
+# readlink.m4 serial 9
+dnl Copyright (C) 2003, 2007, 2009, 2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,6 +12,39 @@ AC_DEFUN([gl_FUNC_READLINK],
     HAVE_READLINK=0
     AC_LIBOBJ([readlink])
     gl_PREREQ_READLINK
+  else
+    AC_CACHE_CHECK([whether readlink signature is correct],
+      [gl_cv_decl_readlink_works],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+           [[#include <unistd.h>
+      /* Cause compilation failure if original declaration has wrong type.  */
+      ssize_t readlink (const char *, char *, size_t);]])],
+         [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
+    dnl Solaris 9 ignores trailing slash.
+    dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
+    AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
+      [gl_cv_func_readlink_works],
+      [# We have readlink, so assume ln -s works.
+       ln -s conftest.no-such conftest.link
+       ln -s conftest.link conftest.lnk2
+       AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+           [[#include <unistd.h>
+]], [[char buf[20];
+      return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
+         [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
+         [gl_cv_func_readlink_works="guessing no"])
+      rm -f conftest.link conftest.lnk2])
+    if test "$gl_cv_func_readlink_works" != yes; then
+      AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
+        fails to recognize a trailing slash.])
+      REPLACE_READLINK=1
+      AC_LIBOBJ([readlink])
+    elif test "$gl_cv_decl_readlink_works" != yes; then
+      REPLACE_READLINK=1
+      AC_LIBOBJ([readlink])
+    fi
   fi
 ])