NEWS.stable: log cherry-pick [a5a35f0]->[c4596b1] freopen: Documentation.

[gnulib.git] / m4 / lstat.m4

diff --git a/m4/lstat.m4 b/m4/lstat.m4
index 5dbd16e..fe161d4 100644 (file)
--- a/m4/lstat.m4
+++ b/m4/lstat.m4
@@ -1,6 +1,6 @@
-# serial 20
+# serial 23
 
-# Copyright (C) 1997-2001, 2003-2010 Free Software Foundation, Inc.
+# Copyright (C) 1997-2001, 2003-2011 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -15,14 +15,56 @@ AC_DEFUN([gl_FUNC_LSTAT],
   dnl "#define lstat stat", and lstat.c is a no-op.
   AC_CHECK_FUNCS_ONCE([lstat])
   if test $ac_cv_func_lstat = yes; then
-    AC_REQUIRE([AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
-    if test $ac_cv_func_lstat_dereferences_slashed_symlink = no; then
-      dnl Note: AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK does AC_LIBOBJ([lstat]).
+    AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+    if test $gl_cv_func_lstat_dereferences_slashed_symlink = no; then
       REPLACE_LSTAT=1
     fi
-    # Prerequisites of lib/lstat.c.
-    AC_REQUIRE([AC_C_INLINE])
   else
     HAVE_LSTAT=0
   fi
 ])
+
+# Prerequisites of lib/lstat.c.
+AC_DEFUN([gl_PREREQ_LSTAT],
+[
+  AC_REQUIRE([AC_C_INLINE])
+  :
+])
+
+AC_DEFUN([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
+[
+  dnl We don't use AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK any more, because it
+  dnl is no longer maintained in Autoconf and because it invokes AC_LIBOBJ.
+  AC_CACHE_CHECK([whether lstat correctly handles trailing slash],
+    [gl_cv_func_lstat_dereferences_slashed_symlink],
+    [rm -f conftest.sym conftest.file
+     echo >conftest.file
+     if test "$as_ln_s" = "ln -s" && ln -s conftest.file conftest.sym; then
+       AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [AC_INCLUDES_DEFAULT],
+            [[struct stat sbuf;
+              /* Linux will dereference the symlink and fail, as required by
+                 POSIX.  That is better in the sense that it means we will not
+                 have to compile and use the lstat wrapper.  */
+              return lstat ("conftest.sym/", &sbuf) == 0;
+            ]])],
+         [gl_cv_func_lstat_dereferences_slashed_symlink=yes],
+         [gl_cv_func_lstat_dereferences_slashed_symlink=no],
+         [# When cross-compiling, be pessimistic so we will end up using the
+          # replacement version of lstat that checks for trailing slashes and
+          # calls lstat a second time when necessary.
+          gl_cv_func_lstat_dereferences_slashed_symlink=no
+         ])
+     else
+       # If the 'ln -s' command failed, then we probably don't even
+       # have an lstat function.
+       gl_cv_func_lstat_dereferences_slashed_symlink=no
+     fi
+     rm -f conftest.sym conftest.file
+    ])
+  test $gl_cv_func_lstat_dereferences_slashed_symlink = yes &&
+    AC_DEFINE_UNQUOTED([LSTAT_FOLLOWS_SLASHED_SYMLINK], [1],
+      [Define to 1 if `lstat' dereferences a symlink specified
+       with a trailing slash.])
+])