(gl_FUNC_DIRFD): Rename from UTILS_FUNC_DIRFD.

[gnulib.git] / m4 / dirfd.m4

diff --git a/m4/dirfd.m4 b/m4/dirfd.m4
index fee5fb2..5f1a9a8 100644 (file)
--- a/m4/dirfd.m4
+++ b/m4/dirfd.m4
@@ -1,12 +1,15 @@
-#serial 1
+#serial 7
 
 dnl Find out how to get the file descriptor associated with an open DIR*.
 dnl From Jim Meyering
 
-AC_DEFUN([UTILS_FUNC_DIRFD],
+AC_DEFUN([gl_FUNC_DIRFD],
 [
+  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
+  AC_REQUIRE([AC_PROG_CPP])
+  AC_REQUIRE([AC_PROG_EGREP])
+
   AC_HEADER_DIRENT
-  AC_REPLACE_FUNCS([dirfd])
   dirfd_headers='
 #if HAVE_DIRENT_H
 # include <dirent.h>
@@ -23,44 +26,56 @@ AC_DEFUN([UTILS_FUNC_DIRFD],
 # endif /* HAVE_NDIR_H */
 #endif /* HAVE_DIRENT_H */
 '
+  AC_CHECK_FUNCS(dirfd)
   AC_CHECK_DECLS([dirfd], , , $dirfd_headers)
-  if test $ac_cv_func_dirfd = no; then
+
+  AC_CACHE_CHECK([whether dirfd is a macro],
+    jm_cv_func_dirfd_macro,
+    [AC_EGREP_CPP([dirent_header_defines_dirfd], [$dirfd_headers
+#ifdef dirfd
+ dirent_header_defines_dirfd
+#endif],
+       jm_cv_func_dirfd_macro=yes,
+       jm_cv_func_dirfd_macro=no)])
+
+  # Use the replacement only if we have no function, macro,
+  # or declaration with that name.
+  if test $ac_cv_func_dirfd,$ac_cv_have_decl_dirfd,$jm_cv_func_dirfd_macro \
+      = no,no,no; then
+    AC_REPLACE_FUNCS([dirfd])
     AC_CACHE_CHECK(
              [how to get the file descriptor associated with an open DIR*],
-                  ac_cv_sys_dir_to_fd,
+                  gl_cv_sys_dir_fd_member_name,
       [
-        dirfd_save_DEFS=$DEFS
-       for ac_expr in                                          \
-                                                               \
-           '# Solaris'                                         \
-           'dir_p->d_fd'                                       \
-                                                               \
-           '# Solaris'                                         \
-           'dir_p->dd_fd'                                      \
-                                                               \
-           '# systems for which the info is not available'     \
-           -1                                                  \
-           ; do
+        dirfd_save_CFLAGS=$CFLAGS
+       for ac_expr in d_fd dd_fd; do
 
-         # Skip each embedded comment.
-         case "$ac_expr" in '#'*) continue;; esac
-
-         DEFS="$DEFS -DDIR_TO_FD=$ac_expr"
+         CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr"
          AC_TRY_COMPILE(
            [$dirfd_headers
            ],
-           [DIR *dir_p = opendir("."); (void) ($ac_expr);],
-           dir_fd_done=yes
+           [DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;],
+           dir_fd_found=yes
          )
-         DEFS=$dirfd_save_DEFS
-         test "$dir_fd_done" = yes && break
+         CFLAGS=$dirfd_save_CFLAGS
+         test "$dir_fd_found" = yes && break
        done
+       test "$dir_fd_found" = yes || ac_expr=no_such_member
 
-       ac_cv_sys_dir_to_fd=$ac_expr
+       gl_cv_sys_dir_fd_member_name=$ac_expr
       ]
     )
-    AC_DEFINE_UNQUOTED(DIR_TO_FD,
-      $ac_cv_sys_dir_to_fd,
-      [the file descriptor associated with `dir_p'])
+    if test $gl_cv_sys_dir_fd_member_name != no_such_member; then
+      AC_DEFINE_UNQUOTED(DIR_FD_MEMBER_NAME,
+       $gl_cv_sys_dir_fd_member_name,
+       [the name of the file descriptor member of DIR])
+    fi
+    AH_VERBATIM(DIR_TO_FD,
+               [#ifdef DIR_FD_MEMBER_NAME
+# define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME)
+#else
+# define DIR_TO_FD(Dir_p) -1
+#endif
+])
   fi
 ])