emacs/m4/xattr.m4

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# xattr.m4
# serial 7
dnl Copyright (C) 2003-2024 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.
# Check for Extended Attributes (Linux)
AC_DEFUN([gl_FUNC_XATTR],
[
AC_ARG_ENABLE([xattr],
AS_HELP_STRING([[--disable-xattr]],
[do not support extended attributes]),
[use_xattr=$enableval], [use_xattr=yes])
LIB_XATTR=
AC_SUBST([LIB_XATTR])
if test "$use_xattr" = yes; then
AC_CACHE_CHECK([for xattr library with ATTR_ACTION_PERMISSIONS],
[gl_cv_xattr_lib],
[gl_cv_xattr_lib=no
AC_LANG_CONFTEST(
[AC_LANG_PROGRAM(
[[#include <attr/error_context.h>
#include <attr/libattr.h>
static int
is_attr_permissions (const char *name, struct error_context *ctx)
{
return attr_copy_action (name, ctx) == ATTR_ACTION_PERMISSIONS;
}
]],
[[return attr_copy_fd ("/", 0, "/", 0, is_attr_permissions, 0);
]])])
AC_LINK_IFELSE([],
[gl_cv_xattr_lib='none required'],
[xattr_saved_LIBS=$LIBS
LIBS="-lattr $LIBS"
AC_LINK_IFELSE([], [gl_cv_xattr_lib=-lattr])
LIBS=$xattr_saved_LIBS])])
if test "$gl_cv_xattr_lib" = no; then
AC_MSG_WARN([libattr development library was not found or not usable.])
AC_MSG_WARN([AC_PACKAGE_NAME will be built without xattr support.])
use_xattr=no
elif test "$gl_cv_xattr_lib" != 'none required'; then
LIB_XATTR=$gl_cv_xattr_lib
fi
fi
if test "$use_xattr" = yes; then
AC_DEFINE([USE_XATTR], [1],
[Define to 1 to use the Linux extended attributes library.])
fi
])