| 1 | # serial 26 -*- Autoconf -*-
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| 2 |
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| 3 | dnl Find out how to get the file descriptor associated with an open DIR*.
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| 4 |
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| 5 | # Copyright (C) 2001-2006, 2008-2021 Free Software Foundation, Inc.
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| 6 | # This file is free software; the Free Software Foundation
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| 7 | # gives unlimited permission to copy and/or distribute it,
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| 8 | # with or without modifications, as long as this notice is preserved.
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| 9 |
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| 10 | dnl From Jim Meyering
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| 11 |
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| 12 | AC_DEFUN([gl_FUNC_DIRFD],
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| 13 | [
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| 14 | AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
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| 15 | AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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| 16 |
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| 17 | dnl Persuade glibc <dirent.h> to declare dirfd().
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| 18 | AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
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| 19 |
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| 20 | AC_CHECK_FUNCS([dirfd])
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| 21 | AC_CHECK_DECLS([dirfd], , ,
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| 22 | [[#include <sys/types.h>
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| 23 | #include <dirent.h>]])
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| 24 | if test $ac_cv_have_decl_dirfd = no; then
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| 25 | HAVE_DECL_DIRFD=0
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| 26 | fi
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| 27 |
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| 28 | AC_CACHE_CHECK([whether dirfd is a macro],
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| 29 | [gl_cv_func_dirfd_macro],
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| 30 | [AC_EGREP_CPP([dirent_header_defines_dirfd], [
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| 31 | #include <sys/types.h>
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| 32 | #include <dirent.h>
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| 33 | #ifdef dirfd
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| 34 | dirent_header_defines_dirfd
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| 35 | #endif],
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| 36 | [gl_cv_func_dirfd_macro=yes],
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| 37 | [gl_cv_func_dirfd_macro=no])])
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| 38 |
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| 39 | # Use the replacement if we have no function or macro with that name,
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| 40 | # or if OS/2 kLIBC whose dirfd() does not work.
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| 41 | # Replace only if the system declares dirfd already.
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| 42 | case $ac_cv_func_dirfd,$gl_cv_func_dirfd_macro,$host_os,$ac_cv_have_decl_dirfd in
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| 43 | no,no,*,yes | *,*,os2*,yes)
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| 44 | REPLACE_DIRFD=1
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| 45 | AC_DEFINE([REPLACE_DIRFD], [1],
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| 46 | [Define to 1 if gnulib's dirfd() replacement is used.]);;
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| 47 | esac
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| 48 | ])
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| 49 |
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| 50 | dnl Prerequisites of lib/dirfd.c.
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| 51 | AC_DEFUN([gl_PREREQ_DIRFD],
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| 52 | [
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| 53 | AC_CACHE_CHECK([how to get the file descriptor associated with an open DIR*],
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| 54 | [gl_cv_sys_dir_fd_member_name],
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| 55 | [
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| 56 | dirfd_save_CFLAGS=$CFLAGS
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| 57 | for ac_expr in d_fd dd_fd; do
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| 58 |
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| 59 | CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr"
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| 60 | AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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| 61 | #include <sys/types.h>
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| 62 | #include <dirent.h>]],
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| 63 | [[DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;]])],
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| 64 | [dir_fd_found=yes]
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| 65 | )
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| 66 | CFLAGS=$dirfd_save_CFLAGS
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| 67 | test "$dir_fd_found" = yes && break
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| 68 | done
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| 69 | test "$dir_fd_found" = yes || ac_expr=no_such_member
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| 70 |
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| 71 | gl_cv_sys_dir_fd_member_name=$ac_expr
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| 72 | ]
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| 73 | )
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| 74 | if test $gl_cv_sys_dir_fd_member_name != no_such_member; then
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| 75 | AC_DEFINE_UNQUOTED([DIR_FD_MEMBER_NAME],
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| 76 | [$gl_cv_sys_dir_fd_member_name],
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| 77 | [the name of the file descriptor member of DIR])
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| 78 | fi
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| 79 | AH_VERBATIM([DIR_TO_FD],
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| 80 | [#ifdef DIR_FD_MEMBER_NAME
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| 81 | # define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME)
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| 82 | #else
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| 83 | # define DIR_TO_FD(Dir_p) -1
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| 84 | #endif
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| 85 | ])
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| 86 | ])
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