X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Flinkat.m4;h=0cf8d800d4d2071c0e715164fbc5a5a67bd8573c;hb=d9c5af0679bed502b1f978f75cf8a4c41e104263;hp=be68c5fc79145d879001945355c12759dbb29c3d;hpb=c4194dcc56767f8f96bc005088b292f519b13910;p=gnulib.git

diff --git a/m4/linkat.m4 b/m4/linkat.m4
index be68c5fc7..0cf8d800d 100644
--- a/m4/linkat.m4
+++ b/m4/linkat.m4
@@ -1,7 +1,7 @@
-# serial 1
+# serial 6
 # See if we need to provide linkat replacement.
 
-dnl Copyright (C) 2009 Free Software Foundation, Inc.
+dnl Copyright (C) 2009-2011 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.
@@ -11,15 +11,85 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_LINKAT],
 [
   AC_REQUIRE([gl_FUNC_OPENAT])
-  AC_REQUIRE([gl_FUNC_LINK])
   AC_REQUIRE([gl_FUNC_LINK_FOLLOWS_SYMLINK])
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CHECK_FUNCS_ONCE([linkat symlink])
   AC_CHECK_HEADERS_ONCE([sys/param.h])
   if test $ac_cv_func_linkat = no; then
     HAVE_LINKAT=0
-    AC_LIBOBJ([linkat])
-    AC_LIBOBJ([at-func2])
+  else
+    AC_CACHE_CHECK([whether linkat(,AT_SYMLINK_FOLLOW) works],
+      [gl_cv_func_linkat_follow],
+      [rm -rf conftest.f1 conftest.f2
+       touch conftest.f1
+       AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <fcntl.h>
+#include <unistd.h>
+#ifdef __linux__
+/* Linux added linkat in 2.6.16, but did not add AT_SYMLINK_FOLLOW
+   until 2.6.18.  Always replace linkat to support older kernels.  */
+choke me
+#endif
+]], [return linkat (AT_FDCWD, "conftest.f1", AT_FDCWD, "conftest.f2",
+                    AT_SYMLINK_FOLLOW);])],
+         [gl_cv_func_linkat_follow=yes],
+         [gl_cv_func_linkat_follow="need runtime check"])
+       rm -rf conftest.f1 conftest.f2])
+    AC_CACHE_CHECK([whether linkat handles trailing slash correctly],
+      [gl_cv_func_linkat_slash],
+      [rm -rf conftest.a conftest.b conftest.c conftest.d
+       AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <unistd.h>
+              #include <fcntl.h>
+              #include <errno.h>
+              #include <stdio.h>
+            ]],
+            [[int result;
+              int fd;
+              /* Create a regular file.  */
+              fd = open ("conftest.a", O_CREAT | O_EXCL | O_WRONLY, 0600);
+              if (fd < 0)
+                return 1;
+              if (write (fd, "hello", 5) < 5)
+                return 2;
+              if (close (fd) < 0)
+                return 3;
+              /* Test whether hard links are supported on the current
+                 device.  */
+              if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.b",
+                          AT_SYMLINK_FOLLOW) < 0)
+                return 0;
+              result = 0;
+              /* Test whether a trailing "/" is treated like "/.".  */
+              if (linkat (AT_FDCWD, "conftest.a/", AT_FDCWD, "conftest.c",
+                          AT_SYMLINK_FOLLOW) == 0)
+                result |= 4;
+              if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.d/",
+                          AT_SYMLINK_FOLLOW) == 0)
+                result |= 8;
+              return result;
+            ]])],
+         [gl_cv_func_linkat_slash=yes],
+         [gl_cv_func_linkat_slash=no],
+         [# Guess yes on glibc systems, no otherwise.
+          case "$host_os" in
+            *-gnu*) gl_cv_func_linkat_slash="guessing yes";;
+            *)      gl_cv_func_linkat_slash="guessing no";;
+          esac
+         ])
+       rm -rf conftest.a conftest.b conftest.c conftest.d])
+    case "$gl_cv_func_linkat_slash" in
+      *yes) gl_linkat_slash_bug=0 ;;
+      *)    gl_linkat_slash_bug=1 ;;
+    esac
+    if test "$gl_cv_func_linkat_follow" != yes \
+       || test $gl_linkat_slash_bug = 1; then
+      REPLACE_LINKAT=1
+      AC_DEFINE_UNQUOTED([LINKAT_TRAILING_SLASH_BUG], [$gl_linkat_slash_bug],
+        [Define to 1 if linkat fails to recognize a trailing slash.])
+    fi
   fi
 ])