1# fchdir.m4 serial 25 2dnl Copyright (C) 2006-2020 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 $HAVE_FCHDIR = 0; then 20 AC_LIBOBJ([fchdir]) 21 gl_PREREQ_FCHDIR 22 AC_DEFINE([REPLACE_FCHDIR], [1], 23 [Define to 1 if gnulib's fchdir() replacement is used.]) 24 dnl We must also replace anything that can manipulate a directory fd, 25 dnl to keep our bookkeeping up-to-date. We don't have to replace 26 dnl fstatat, since no platform has fstatat but lacks fchdir. 27 AC_CACHE_CHECK([whether open can visit directories], 28 [gl_cv_func_open_directory_works], 29 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <fcntl.h> 30]], [return open(".", O_RDONLY) < 0;])], 31 [gl_cv_func_open_directory_works=yes], 32 [gl_cv_func_open_directory_works=no], 33 [case "$host_os" in 34 # Guess yes on Linux systems. 35 linux-* | linux) gl_cv_func_open_directory_works="guessing yes" ;; 36 # Guess yes on glibc systems. 37 *-gnu* | gnu*) gl_cv_func_open_directory_works="guessing yes" ;; 38 # Guess no on native Windows. 39 mingw*) gl_cv_func_open_directory_works="guessing no" ;; 40 # If we don't know, obey --enable-cross-guesses. 41 *) gl_cv_func_open_directory_works="$gl_cross_guess_normal" ;; 42 esac 43 ])]) 44 case "$gl_cv_func_open_directory_works" in 45 *yes) ;; 46 *) 47 AC_DEFINE([REPLACE_OPEN_DIRECTORY], [1], [Define to 1 if open() should 48work around the inability to open a directory.]) 49 ;; 50 esac 51 fi 52]) 53 54# Determine whether to use the overrides in lib/fchdir.c. 55AC_DEFUN([gl_TEST_FCHDIR], 56[ 57 AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) 58 AC_CHECK_FUNCS_ONCE([fchdir]) 59 if test $ac_cv_func_fchdir = no; then 60 HAVE_FCHDIR=0 61 fi 62]) 63 64# Prerequisites of lib/fchdir.c. 65AC_DEFUN([gl_PREREQ_FCHDIR], [:]) 66