[ChangeLog]

[bpt/emacs.git] / m4 / lstat.m4

diff --git a/m4/lstat.m4 b/m4/lstat.m4
new file mode 100644 (file)
index 0000000..b9b22a6
--- /dev/null
+++ b/m4/lstat.m4
@@ -0,0 +1,69 @@
+# serial 21
+
+# 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,
+# with or without modifications, as long as this notice is preserved.
+
+dnl From Jim Meyering.
+
+AC_DEFUN([gl_FUNC_LSTAT],
+[
+  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+  dnl If lstat does not exist, the replacement <sys/stat.h> does
+  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 $ac_cv_func_lstat_dereferences_slashed_symlink = no; then
+      dnl Note: AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK does AC_LIBOBJ([lstat]).
+      REPLACE_LSTAT=1
+    fi
+    # Prerequisites of lib/lstat.c.
+    AC_REQUIRE([AC_C_INLINE])
+  else
+    HAVE_LSTAT=0
+  fi
+])
+
+# Redefine AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK, because it is no longer
+# maintained in Autoconf.
+AC_DEFUN([AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
+[
+  AC_CACHE_CHECK([whether lstat correctly handles trailing slash],
+    [ac_cv_func_lstat_dereferences_slashed_symlink],
+    [rm -f conftest.sym conftest.file
+     echo >conftest.file
+     if test "$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;
+            ]])],
+         [ac_cv_func_lstat_dereferences_slashed_symlink=yes],
+         [ac_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.
+          ac_cv_func_lstat_dereferences_slashed_symlink=no
+         ])
+     else
+       # If the 'ln -s' command failed, then we probably don't even
+       # have an lstat function.
+       ac_cv_func_lstat_dereferences_slashed_symlink=no
+     fi
+     rm -f conftest.sym conftest.file
+    ])
+  test $ac_cv_func_lstat_dereferences_slashed_symlink = yes &&
+    AC_DEFINE_UNQUOTED([LSTAT_FOLLOWS_SLASHED_SYMLINK], [1],
+      [Define to 1 if `lstat' dereferences a symlink specified
+       with a trailing slash.])
+  if test "x$ac_cv_func_lstat_dereferences_slashed_symlink" = xno; then
+    AC_LIBOBJ([lstat])
+  fi
+])