1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
| | # 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.
# 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])
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 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 "$gl_cv_func_malloc_posix" = yes; then
AC_DEFINE([HAVE_MALLOC_POSIX], [1],
[Define if malloc, realloc, and calloc set errno on allocation failure.])
else
REPLACE_MALLOC=1
fi
])
# Test whether malloc, realloc, calloc set errno to ENOMEM on failure.
# Set gl_cv_func_malloc_posix to yes or no accordingly.
AC_DEFUN([gl_CHECK_MALLOC_POSIX],
[
AC_REQUIRE([AC_CANONICAL_HOST])
AC_CACHE_CHECK([whether malloc, realloc, calloc set errno on failure],
[gl_cv_func_malloc_posix],
[
dnl It is too dangerous to try to allocate a large amount of memory:
dnl some systems go to their knees when you do that. So assume that
dnl all Unix implementations of the function set errno on failure,
dnl except on those platforms where we have seen 'test-malloc-gnu',
dnl 'test-realloc-gnu', 'test-calloc-gnu' fail.
case "$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
])
])
|