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# calloc.m4
# serial 36
dnl Copyright (C) 2004-2025 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.
# Written by Jim Meyering.
# Determine whether calloc (N, S) returns non-NULL when N*S is zero,
# and returns NULL when N*S overflows.
# If so, define HAVE_CALLOC. Otherwise, define calloc to rpl_calloc
# and arrange to use a calloc wrapper function that does work in that case.
# gl_FUNC_CALLOC_IF([IF-WORKS], [IF-NOT])
# ---------------------------------------
# If calloc is compatible with GNU calloc, run IF-WORKS, otherwise, IF-NOT.
AC_DEFUN([gl_FUNC_CALLOC_IF],
[
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether calloc (0, n) and calloc (n, 0) return nonnull],
[gl_cv_func_calloc_0_nonnull],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdlib.h>
/* Use pcalloc to test; "volatile" prevents the compiler
from optimizing the calloc call away. */
void *(*volatile pcalloc) (size_t, size_t) = calloc;]],
[[void *p = pcalloc (0, 0);
int result = !p;
free (p);
return result;]])],
[gl_cv_func_calloc_0_nonnull=yes],
[gl_cv_func_calloc_0_nonnull=no],
[AS_CASE([$host_os],
[# Guess yes on platforms where we know the result.
*-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
| gnu* | *-musl* | midipix* | midnightbsd* \
| hpux* | solaris* | cygwin* | mingw* | windows* | msys*],
[gl_cv_func_calloc_0_nonnull="guessing yes"],
[# If we don't know, obey --enable-cross-guesses.
gl_cv_func_calloc_0_nonnull="$gl_cross_guess_normal"])])])
AS_CASE([$gl_cv_func_calloc_0_nonnull], [*yes], [$1], [$2])
])
# gl_FUNC_CALLOC_GNU
# ------------------
# Replace calloc if it is not compatible with GNU libc.
AC_DEFUN([gl_FUNC_CALLOC_GNU],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_CALLOC_POSIX])
dnl Through the dependency on module extensions-aix, _LINUX_SOURCE_COMPAT
dnl gets defined already before this macro gets invoked. This helps
dnl if !(__VEC__ || __AIXVEC), and doesn't hurt otherwise.
REPLACE_CALLOC_FOR_CALLOC_GNU="$REPLACE_CALLOC_FOR_CALLOC_POSIX"
if test $REPLACE_CALLOC_FOR_CALLOC_GNU = 0; then
gl_FUNC_CALLOC_IF([], [REPLACE_CALLOC_FOR_CALLOC_GNU=1])
fi
])# gl_FUNC_CALLOC_GNU
# gl_FUNC_CALLOC_POSIX
# --------------------
# Test whether 'calloc' is POSIX compliant (sets errno to ENOMEM when it
# fails, and doesn't mess up with ptrdiff_t or size_t overflow),
# and replace calloc if it is not.
AC_DEFUN([gl_FUNC_CALLOC_POSIX],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
REPLACE_CALLOC_FOR_CALLOC_POSIX=$REPLACE_MALLOC_FOR_MALLOC_POSIX
dnl Although in theory we should also test for size_t overflow,
dnl in practice testing for ptrdiff_t overflow suffices
dnl since PTRDIFF_MAX <= SIZE_MAX on all known Gnulib porting targets.
dnl A separate size_t test would slow down 'configure'.
])
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