1# fchdir.m4 serial 26 2dnl Copyright (C) 2006-2021 Free Software Foundation, Inc. 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7AC_DEFUN([gl_FUNC_FCHDIR], 8[ 9 AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) 10 AC_REQUIRE([gl_DIRENT_H_DEFAULTS]) 11 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles 12 13 AC_CHECK_DECLS_ONCE([fchdir]) 14 if test $ac_cv_have_decl_fchdir = no; then 15 HAVE_DECL_FCHDIR=0 16 fi 17 18 AC_REQUIRE([gl_TEST_FCHDIR]) 19 if test $HAVE_FCHDIR = 0; then 20 AC_LIBOBJ([fchdir]) 21 gl_PREREQ_FCHDIR 22 AC_DEFINE([REPLACE_FCHDIR], [1], 23 [Define to 1 if gnulib's fchdir() replacement is used.]) 24 dnl We must also replace anything that can manipulate a directory fd, 25 dnl to keep our bookkeeping up-to-date. We don't have to replace 26 dnl fstatat, since no platform has fstatat but lacks fchdir. 27 AC_CACHE_CHECK([whether open can visit directories], 28 [gl_cv_func_open_directory_works], 29 [AC_RUN_IFELSE( 30 [AC_LANG_PROGRAM( 31 [[#include <fcntl.h> 32 ]GL_MDA_DEFINES], 33 [[return open(".", O_RDONLY) < 0;]])], 34 [gl_cv_func_open_directory_works=yes], 35 [gl_cv_func_open_directory_works=no], 36 [case "$host_os" in 37 # Guess yes on Linux systems. 38 linux-* | linux) gl_cv_func_open_directory_works="guessing yes" ;; 39 # Guess yes on glibc systems. 40 *-gnu* | gnu*) gl_cv_func_open_directory_works="guessing yes" ;; 41 # Guess no on native Windows. 42 mingw*) gl_cv_func_open_directory_works="guessing no" ;; 43 # If we don't know, obey --enable-cross-guesses. 44 *) gl_cv_func_open_directory_works="$gl_cross_guess_normal" ;; 45 esac 46 ])]) 47 case "$gl_cv_func_open_directory_works" in 48 *yes) ;; 49 *) 50 AC_DEFINE([REPLACE_OPEN_DIRECTORY], [1], [Define to 1 if open() should 51work around the inability to open a directory.]) 52 ;; 53 esac 54 fi 55]) 56 57# Determine whether to use the overrides in lib/fchdir.c. 58AC_DEFUN([gl_TEST_FCHDIR], 59[ 60 AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) 61 AC_CHECK_FUNCS_ONCE([fchdir]) 62 if test $ac_cv_func_fchdir = no; then 63 HAVE_FCHDIR=0 64 fi 65]) 66 67# Prerequisites of lib/fchdir.c. 68AC_DEFUN([gl_PREREQ_FCHDIR], [:]) 69