-# 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.
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
])