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# realloc.m4
# serial 36
dnl Copyright (C) 2007, 2009-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
dnl This file is offered as-is, without any warranty.
# An an experimental option, the user can request a sanitized realloc()
# implementation, i.e. one that aborts upon undefined behaviour,
# by setting
# gl_cv_func_realloc_sanitize=yes
# at configure time.
AC_DEFUN([gl_FUNC_REALLOC_SANITIZED],
[
AC_CACHE_CHECK([whether realloc should abort upon undefined behaviour],
[gl_cv_func_realloc_sanitize],
[test -n "$gl_cv_func_realloc_sanitize" || gl_cv_func_realloc_sanitize=no])
])
m4_version_prereq([2.73], [], [
# This is copied from upstream Autoconf here:
# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=f8c82d292699fbce6d60abb46259a3781578f7fc#n1483
# _AC_FUNC_REALLOC_IF(IF-WORKS, IF-NOT[, UNKNOWN-ASSUME])
# -------------------------------------------------------
# If 'realloc (0, 0)' returns nonnull, run IF-WORKS, otherwise, IF-NOT.
# If it is not known whether it works, assume the shell word UNKNOWN-ASSUME,
# which should end in "yes" or in something else (the latter is the default).
AC_DEFUN([_AC_FUNC_REALLOC_IF],
[
AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
AC_CACHE_CHECK([whether realloc (0, 0) returns nonnull],
[ac_cv_func_realloc_0_nonnull],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdlib.h>
/* Use prealloc to test; 'volatile' prevents the compiler
from optimizing the realloc call away. */
void *(*volatile prealloc) (void *, size_t) = realloc;]],
[[void *p = prealloc (0, 0);
int result = !p;
free (p);
return result;]])],
[ac_cv_func_realloc_0_nonnull=yes],
[ac_cv_func_realloc_0_nonnull=no],
[AS_CASE([$host_os],
[# Guess yes on platforms where we know the result.
*-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
| gnu* | *-musl* | midipix* | midnightbsd* \
| hpux* | solaris* | cygwin* | mingw* | windows* | msys*],
[ac_cv_func_realloc_0_nonnull="guessing yes"],
[# Guess as follows if we don't know.
ac_cv_func_realloc_0_nonnull=m4_default([$3], ["guessing no"])])])])
AS_CASE([$ac_cv_func_realloc_0_nonnull], [*yes], [$1], [$2])
])# _AC_FUNC_REALLOC_IF
])
# gl_FUNC_REALLOC_POSIX
# ---------------------
# Test whether 'realloc' is POSIX compliant (sets errno to ENOMEM when it
# fails, and doesn't mess up with ptrdiff_t overflow),
# and replace realloc if it is not.
AC_DEFUN([gl_FUNC_REALLOC_POSIX],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
AC_REQUIRE([gl_FUNC_REALLOC_SANITIZED])
if test "$gl_cv_func_realloc_sanitize" != no; then
REPLACE_REALLOC_FOR_REALLOC_POSIX=1
AC_DEFINE([NEED_SANITIZED_REALLOC], [1],
[Define to 1 if realloc should abort upon undefined behaviour.])
else
if test $REPLACE_MALLOC_FOR_MALLOC_POSIX = 1; then
REPLACE_REALLOC_FOR_REALLOC_POSIX=1
fi
fi
])
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