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-rw-r--r--gl/m4/malloc.m4175
1 files changed, 175 insertions, 0 deletions
diff --git a/gl/m4/malloc.m4 b/gl/m4/malloc.m4
new file mode 100644
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--- /dev/null
+++ b/gl/m4/malloc.m4
@@ -0,0 +1,175 @@
+# malloc.m4 serial 28
+dnl Copyright (C) 2007, 2009-2022 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.
+
+# This is adapted with modifications from upstream Autoconf here:
+# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n949
+AC_DEFUN([_AC_FUNC_MALLOC_IF],
+[
+ AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+ AC_CACHE_CHECK([whether malloc (0) returns nonnull],
+ [ac_cv_func_malloc_0_nonnull],
+ [AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <stdlib.h>
+ ]],
+ [[void *p = malloc (0);
+ int result = !p;
+ free (p);
+ return result;]])
+ ],
+ [ac_cv_func_malloc_0_nonnull=yes],
+ [ac_cv_func_malloc_0_nonnull=no],
+ [case "$host_os" in
+ # Guess yes on platforms where we know the result.
+ *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+ | gnu* | *-musl* | midnightbsd* \
+ | hpux* | solaris* | cygwin* | mingw* | msys* )
+ ac_cv_func_malloc_0_nonnull="guessing yes" ;;
+ # If we don't know, obey --enable-cross-guesses.
+ *) ac_cv_func_malloc_0_nonnull="$gl_cross_guess_normal" ;;
+ esac
+ ])
+ ])
+ AS_CASE([$ac_cv_func_malloc_0_nonnull], [*yes], [$1], [$2])
+])# _AC_FUNC_MALLOC_IF
+
+# gl_FUNC_MALLOC_GNU
+# ------------------
+# Replace malloc if it is not compatible with GNU libc.
+AC_DEFUN([gl_FUNC_MALLOC_GNU],
+[
+ AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+ AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
+ REPLACE_MALLOC_FOR_MALLOC_GNU="$REPLACE_MALLOC_FOR_MALLOC_POSIX"
+ if test $REPLACE_MALLOC_FOR_MALLOC_GNU = 0; then
+ _AC_FUNC_MALLOC_IF([], [REPLACE_MALLOC_FOR_MALLOC_GNU=1])
+ fi
+])
+
+# gl_FUNC_MALLOC_PTRDIFF
+# ----------------------
+# Test whether malloc (N) reliably fails when N exceeds PTRDIFF_MAX,
+# and replace malloc otherwise.
+AC_DEFUN([gl_FUNC_MALLOC_PTRDIFF],
+[
+ AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+ AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
+ test "$gl_cv_malloc_ptrdiff" = yes || REPLACE_MALLOC_FOR_MALLOC_POSIX=1
+])
+
+# Test whether malloc, realloc, calloc refuse to create objects
+# larger than what can be expressed in ptrdiff_t.
+# Set gl_cv_func_malloc_gnu to yes or no accordingly.
+AC_DEFUN([gl_CHECK_MALLOC_PTRDIFF],
+[
+ AC_CACHE_CHECK([whether malloc is ptrdiff_t safe],
+ [gl_cv_malloc_ptrdiff],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <stdint.h>
+ ]],
+ [[/* 64-bit ptrdiff_t is so wide that no practical platform
+ can exceed it. */
+ #define WIDE_PTRDIFF (PTRDIFF_MAX >> 31 >> 31 != 0)
+
+ /* On rare machines where size_t fits in ptrdiff_t there
+ is no problem. */
+ #define NARROW_SIZE (SIZE_MAX <= PTRDIFF_MAX)
+
+ /* glibc 2.30 and later malloc refuses to exceed ptrdiff_t
+ bounds even on 32-bit platforms. We don't know which
+ non-glibc systems are safe. */
+ #define KNOWN_SAFE (2 < __GLIBC__ + (30 <= __GLIBC_MINOR__))
+
+ #if WIDE_PTRDIFF || NARROW_SIZE || KNOWN_SAFE
+ return 0;
+ #else
+ #error "malloc might not be ptrdiff_t safe"
+ syntax error
+ #endif
+ ]])],
+ [gl_cv_malloc_ptrdiff=yes],
+ [gl_cv_malloc_ptrdiff=no])
+ ])
+])
+
+# gl_FUNC_MALLOC_POSIX
+# --------------------
+# Test whether 'malloc' is POSIX compliant (sets errno to ENOMEM when it
+# fails, and doesn't mess up with ptrdiff_t overflow), and replace
+# malloc if it is not.
+AC_DEFUN([gl_FUNC_MALLOC_POSIX],
+[
+ AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+ AC_REQUIRE([gl_FUNC_MALLOC_PTRDIFF])
+ AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
+ if test "$gl_cv_func_malloc_posix" = yes; then
+ AC_DEFINE([HAVE_MALLOC_POSIX], [1],
+ [Define if malloc, realloc, and calloc set errno on allocation failure.])
+ else
+ REPLACE_MALLOC_FOR_MALLOC_POSIX=1
+ fi
+])
+
+# Test whether malloc, realloc, calloc set errno to ENOMEM on failure.
+# Set gl_cv_func_malloc_posix to yes or no accordingly.
+AC_DEFUN([gl_CHECK_MALLOC_POSIX],
+[
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_CACHE_CHECK([whether malloc, realloc, calloc set errno on failure],
+ [gl_cv_func_malloc_posix],
+ [
+ dnl It is too dangerous to try to allocate a large amount of memory:
+ dnl some systems go to their knees when you do that. So assume that
+ dnl all Unix implementations of the function set errno on failure,
+ dnl except on those platforms where we have seen 'test-malloc-gnu',
+ dnl 'test-realloc-gnu', 'test-calloc-gnu' fail.
+ case "$host_os" in
+ mingw*)
+ gl_cv_func_malloc_posix=no ;;
+ irix* | solaris*)
+ dnl On IRIX 6.5, the three functions return NULL with errno unset
+ dnl when the argument is larger than PTRDIFF_MAX.
+ dnl On Solaris 11.3, the three functions return NULL with errno set
+ dnl to EAGAIN, not ENOMEM, when the argument is larger than
+ dnl PTRDIFF_MAX.
+ dnl Here is a test program:
+m4_divert_push([KILL])
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#define ptrdiff_t long
+#ifndef PTRDIFF_MAX
+# define PTRDIFF_MAX ((ptrdiff_t) ((1UL << (8 * sizeof (ptrdiff_t) - 1)) - 1))
+#endif
+
+int main ()
+{
+ void *p;
+
+ fprintf (stderr, "PTRDIFF_MAX = %lu\n", (unsigned long) PTRDIFF_MAX);
+
+ errno = 0;
+ p = malloc ((unsigned long) PTRDIFF_MAX + 1);
+ fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+ errno = 0;
+ p = calloc (PTRDIFF_MAX / 2 + 1, 2);
+ fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+ errno = 0;
+ p = realloc (NULL, (unsigned long) PTRDIFF_MAX + 1);
+ fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+ return 0;
+}
+m4_divert_pop([KILL])
+ gl_cv_func_malloc_posix=no ;;
+ *)
+ gl_cv_func_malloc_posix=yes ;;
+ esac
+ ])
+])