The `regex' struct is both input and output.

[gnulib.git] / m4 / dirfd.m4

diff --git a/m4/dirfd.m4 b/m4/dirfd.m4
index e02b401..27914de 100644 (file)
--- a/m4/dirfd.m4
+++ b/m4/dirfd.m4
@@ -1,50 +1,82 @@
-#serial 1
+#serial 3
 
 dnl Find out how to get the file descriptor associated with an open DIR*.
 dnl From Jim Meyering
 
 AC_DEFUN([UTILS_FUNC_DIRFD],
 [
-  AC_REPLACE_FUNCS([dirfd])
-  AC_CHECK_DECLS([dirfd])
-  if test $ac_cv_func_dirfd = no; then
+  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
+  dirfd_headers='
+#if HAVE_DIRENT_H
+# include <dirent.h>
+#else /* not HAVE_DIRENT_H */
+# define dirent direct
+# if HAVE_SYS_NDIR_H
+#  include <sys/ndir.h>
+# endif /* HAVE_SYS_NDIR_H */
+# if HAVE_SYS_DIR_H
+#  include <sys/dir.h>
+# endif /* HAVE_SYS_DIR_H */
+# if HAVE_NDIR_H
+#  include <ndir.h>
+# endif /* HAVE_NDIR_H */
+#endif /* HAVE_DIRENT_H */
+'
+  AC_CHECK_FUNCS(dirfd)
+  AC_CHECK_DECLS([dirfd], , , $dirfd_headers)
+
+  AC_CACHE_CHECK([whether dirfd is a macro],
+    jm_cv_func_dirfd_macro,
+    AC_EGREP_CPP([dirent_header_defines_dirfd], [$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,$jm_cv_func_dirfd_macro \
+      = no,no,no; then
+    AC_REPLACE_FUNCS([dirfd])
     AC_CACHE_CHECK(
              [how to get the file descriptor associated with an open DIR*],
-                  ac_cv_sys_dir_to_fd,
+                  ac_cv_sys_dir_fd_member_name,
       [
-        dirfd_save_DEFS=$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=$ac_expr"
          AC_TRY_COMPILE(
-           [#include <sys/types.h>
-            #include <dirent.h>
+           [$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=-1
 
-       ac_cv_sys_dir_to_fd=$ac_expr
+       ac_cv_sys_dir_fd_member_name=$ac_expr
       ]
     )
-    AC_DEFINE_UNQUOTED(DIR_TO_FD,
-      $ac_cv_sys_dir_to_fd,
-      [the file descriptor associated with `dir_p'])
+    if test $ac_cv_have_decl_dirfd = -1; then
+      AC_DEFINE_UNQUOTED(DIR_FD_MEMBER_NAME,
+       $ac_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
 ])