1 # truncate.m4 serial 3 -*- Autoconf -*-
2 dnl Copyright (C) 2017-2021 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_TRUNCATE],
9 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10 AC_REQUIRE([AC_CANONICAL_HOST])
12 AC_CHECK_FUNCS_ONCE([truncate])
13 dnl AC_CHECK_FUNC is not enough here, because when compiling for Android 4.4
14 dnl or older with _FILE_OFFSET_BITS=64, truncate() is not declared. There
15 dnl is a function 'truncate' in libc, but it is unsuitable, because it takes
16 dnl only a 32-bit offset argument.
17 AC_CHECK_DECL([truncate], , , [[#include <unistd.h>]])
18 if test $ac_cv_have_decl_truncate = yes; then
19 m4_ifdef([gl_LARGEFILE], [
22 dnl Native Windows, and Large File Support is requested.
23 dnl The mingw64 truncate64() function is based on ftruncate64(),
24 dnl which is unreliable (it may delete the file, see
25 dnl <https://web.archive.org/web/20160425005423/http://mingw-w64.sourcearchive.com/documentation/2.0-1/ftruncate64_8c_source.html>).
26 dnl Use gnulib's ftruncate() and truncate() implementation instead.
33 if test $REPLACE_TRUNCATE = 0; then
34 dnl Check for AIX 7.2 bug with trailing slash.
35 AC_CACHE_CHECK([whether truncate rejects trailing slashes],
36 [gl_cv_func_truncate_works],
37 [echo foo > conftest.tmp
43 if (!truncate ("conftest.tmp/", 2))
48 [gl_cv_func_truncate_works=yes],
49 [gl_cv_func_truncate_works=no],
51 # Guess yes on Linux systems.
52 linux-* | linux) gl_cv_func_truncate_works="guessing yes" ;;
53 # Guess yes on glibc systems.
54 *-gnu* | gnu*) gl_cv_func_truncate_works="guessing yes" ;;
55 # Guess no on AIX systems.
56 aix*) gl_cv_func_truncate_works="guessing no" ;;
57 # If we don't know, obey --enable-cross-guesses.
58 *) gl_cv_func_truncate_works="$gl_cross_guess_normal" ;;
63 case "$gl_cv_func_truncate_works" in
66 AC_DEFINE([TRUNCATE_TRAILING_SLASH_BUG], [1],
67 [Define to 1 if truncate mishandles trailing slash.])
74 if test $ac_cv_func_truncate = yes; then
75 dnl Avoid a conflict with the 'truncate' in libc.
81 # Prerequisites of lib/truncate.c.
82 AC_DEFUN([gl_PREREQ_TRUNCATE], [:])