| 1 | # free.m4 serial 6
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| 2 | # Copyright (C) 2003-2005, 2009-2021 Free Software Foundation, Inc.
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| 3 | # This file is free software; the Free Software Foundation
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| 4 | # gives unlimited permission to copy and/or distribute it,
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| 5 | # with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | # Written by Paul Eggert and Bruno Haible.
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| 8 |
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| 9 | AC_DEFUN([gl_FUNC_FREE],
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| 10 | [
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| 11 | AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
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| 12 |
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| 13 | dnl In the next release of POSIX, free must preserve errno.
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| 14 | dnl https://www.austingroupbugs.net/view.php?id=385
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| 15 | dnl https://sourceware.org/bugzilla/show_bug.cgi?id=17924
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| 16 | dnl So far, we know of three platforms that do this:
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| 17 | dnl * glibc >= 2.33, thanks to the fix for this bug:
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| 18 | dnl <https://sourceware.org/bugzilla/show_bug.cgi?id=17924>
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| 19 | dnl * OpenBSD >= 4.5, thanks to this commit:
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| 20 | dnl <https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdlib/malloc.c.diff?r1=1.100&r2=1.101&f=h>
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| 21 | dnl * Solaris, because its malloc() implementation is based on brk(),
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| 22 | dnl not mmap(); hence its free() implementation makes no system calls.
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| 23 | dnl For other platforms, you can only be sure if they state it in their
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| 24 | dnl documentation, or by code inspection of the free() implementation in libc.
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| 25 | AC_CACHE_CHECK([whether free is known to preserve errno],
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| 26 | [gl_cv_func_free_preserves_errno],
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| 27 | [AC_COMPILE_IFELSE(
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| 28 | [AC_LANG_PROGRAM(
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| 29 | [[#include <stdlib.h>
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| 30 | ]],
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| 31 | [[#if 2 < __GLIBC__ + (33 <= __GLIBC_MINOR__)
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| 32 | #elif defined __OpenBSD__
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| 33 | #elif defined __sun
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| 34 | #else
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| 35 | #error "'free' is not known to preserve errno"
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| 36 | #endif
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| 37 | ]])],
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| 38 | [gl_cv_func_free_preserves_errno=yes],
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| 39 | [gl_cv_func_free_preserves_errno=no])
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| 40 | ])
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| 41 |
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| 42 | case $gl_cv_func_free_preserves_errno in
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| 43 | *yes)
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| 44 | AC_DEFINE([HAVE_FREE_POSIX], [1],
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| 45 | [Define if the 'free' function is guaranteed to preserve errno.])
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| 46 | ;;
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| 47 | *) REPLACE_FREE=1 ;;
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| 48 | esac
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| 49 | ])
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| 50 |
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| 51 | # Prerequisites of lib/free.c.
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| 52 | AC_DEFUN([gl_PREREQ_FREE], [:])
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