From 090c4cb9be5a44a9ec45a493ba3acda9f5161b6e Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Sat, 19 Dec 2020 20:19:45 +0100 Subject: free-posix: Assume future POSIX compliance only on OpenBSD and Solaris. * m4/free.m4 (gl_FUNC_FREE): Guess yes only on OpenBSD and Solaris. Don't trust _POSIX_VERSION for this test. --- m4/free.m4 | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'm4/free.m4') diff --git a/m4/free.m4 b/m4/free.m4 index e7a72039e8..53df7439b5 100644 --- a/m4/free.m4 +++ b/m4/free.m4 @@ -1,33 +1,43 @@ -# free.m4 serial 3 +# free.m4 serial 4 # Copyright (C) 2003-2005, 2009-2020 Free Software Foundation, Inc. # This file is free software; the Free Software Foundation # gives unlimited permission to copy and/or distribute it, # with or without modifications, as long as this notice is preserved. -# Written by Paul Eggert. +# Written by Paul Eggert and Bruno Haible. AC_DEFUN([gl_FUNC_FREE], [ AC_REQUIRE([gl_STDLIB_H_DEFAULTS]) + AC_REQUIRE([AC_CANONICAL_HOST]) dnl In the next release of POSIX, free must preserve errno. dnl https://www.austingroupbugs.net/view.php?id=385 dnl https://sourceware.org/bugzilla/show_bug.cgi?id=17924 - dnl For now, assume implementations other than glibc do not preserve errno - dnl unless they set _POSIX_VERSION to the next release number, - dnl whatever that happens to be. + dnl So far, we know of two platforms that do this: + dnl * OpenBSD >= 4.5, thanks to this commit: + dnl + dnl * Solaris, because its malloc() implementation is based on brk(), + dnl not mmap(); hence its free() implementation makes no system calls. + dnl For other platforms, you can only be sure if they state it in their + dnl documentation, or by code inspection of the free() implementation in libc. AC_CACHE_CHECK([whether free is known to preserve errno], [gl_cv_func_free_preserves_errno], - [AC_COMPILE_IFELSE( - [AC_LANG_PROGRAM( - [[#include - ]], - [[#if _POSIX_VERSION <= 200809 - #error "'free' is not known to preserve errno" - #endif - ]])], - [gl_cv_func_free_preserves_errno=yes], - [gl_cv_func_free_preserves_errno=no]) + [case "$host_os" in + # Say yes only if we know it. + openbsd* | solaris*) + gl_cv_func_free_preserves_errno=yes + ;; + # It's no on Linux, for implementations that call munmap(), due to + # /proc/sys/vm/max_map_count. + linux*) + gl_cv_func_free_preserves_errno=no + ;; + # If we don't know, obey --enable-cross-guesses. + *) + gl_cv_func_free_preserves_errno="$gl_cross_guess_normal" + ;; + esac ]) case $gl_cv_func_free_preserves_errno in -- cgit v1.2.1