1 files changed, 123 insertions, 47 deletions

diff --git a/gl/m4/malloc.m4 b/gl/m4/malloc.m4
index 4b24a0b1..972e808a 100644
--- a/gl/m4/malloc.m4
+++ b/gl/m4/malloc.m4
@@ -1,98 +1,174 @@
-# malloc.m4 serial 14
-dnl Copyright (C) 2007, 2009-2013 Free Software Foundation, Inc.
+# malloc.m4 serial 27
+dnl Copyright (C) 2007, 2009-2021 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.
 
-m4_version_prereq([2.70], [] ,[
-
-# This is taken from the following Autoconf patch:
-# http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
+# 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_HEADER_STDC])dnl
   AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
-  AC_CHECK_HEADERS([stdlib.h])
-  AC_CACHE_CHECK([for GNU libc compatible malloc],
+  AC_CACHE_CHECK([whether malloc (0) returns nonnull],
     [ac_cv_func_malloc_0_nonnull],
     [AC_RUN_IFELSE(
        [AC_LANG_PROGRAM(
-          [[#if defined STDC_HEADERS || defined HAVE_STDLIB_H
-            # include <stdlib.h>
-            #else
-            char *malloc ();
-            #endif
+          [[#include <stdlib.h>
           ]],
-          [[return ! malloc (0);]])
+          [[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 "$host_os" in
           # Guess yes on platforms where we know the result.
-          *-gnu* | freebsd* | netbsd* | openbsd* \
-          | hpux* | solaris* | cygwin* | mingw*)
-            ac_cv_func_malloc_0_nonnull=yes ;;
-          # If we don't know, assume the worst.
-          *) ac_cv_func_malloc_0_nonnull=no ;;
+          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+          | gnu* | *-musl* | midnightbsd* \
+          | hpux* | solaris* | cygwin* | mingw* | msys* )
+            ac_cv_func_malloc_0_nonnull="guessing yes" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *) ac_cv_func_malloc_0_nonnull="$gl_cross_guess_normal" ;;
         esac
        ])
     ])
-  AS_IF([test $ac_cv_func_malloc_0_nonnull = yes], [$1], [$2])
+  AS_CASE([$ac_cv_func_malloc_0_nonnull], [*yes], [$1], [$2])
 ])# _AC_FUNC_MALLOC_IF
 
-])
-
 # gl_FUNC_MALLOC_GNU
 # ------------------
-# Test whether 'malloc (0)' is handled like in GNU libc, and replace malloc if
-# it is not.
+# Replace malloc if it is not compatible with GNU libc.
 AC_DEFUN([gl_FUNC_MALLOC_GNU],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
-  dnl _AC_FUNC_MALLOC_IF is defined in Autoconf.
-  _AC_FUNC_MALLOC_IF(
-    [AC_DEFINE([HAVE_MALLOC_GNU], [1],
-               [Define to 1 if your system has a GNU libc compatible 'malloc'
-                function, and to 0 otherwise.])],
-    [AC_DEFINE([HAVE_MALLOC_GNU], [0])
-     REPLACE_MALLOC=1
+  AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
+  if test $REPLACE_MALLOC = 0; then
+    _AC_FUNC_MALLOC_IF([], [REPLACE_MALLOC=1])
+  fi
+])
+
+# gl_FUNC_MALLOC_PTRDIFF
+# ----------------------
+# Test whether malloc (N) reliably fails when N exceeds PTRDIFF_MAX,
+# and replace malloc otherwise.
+AC_DEFUN([gl_FUNC_MALLOC_PTRDIFF],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
+  test "$gl_cv_malloc_ptrdiff" = yes || REPLACE_MALLOC=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 replace malloc if it is not.
+# 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 $gl_cv_func_malloc_posix = yes; then
+  if test "$gl_cv_func_malloc_posix" = yes; then
     AC_DEFINE([HAVE_MALLOC_POSIX], [1],
-      [Define if the 'malloc' function is POSIX compliant.])
+      [Define if malloc, realloc, and calloc set errno on allocation failure.])
   else
     REPLACE_MALLOC=1
   fi
 ])
 
-# Test whether malloc, realloc, calloc are POSIX compliant,
+# 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_CACHE_CHECK([whether malloc, realloc, calloc are POSIX compliant],
+  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 are POSIX compliant.
-      AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM(
-           [[]],
-           [[#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
-             choke me
-             #endif
-            ]])],
-        [gl_cv_func_malloc_posix=yes],
-        [gl_cv_func_malloc_posix=no])
+      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
     ])
 ])