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Diffstat (limited to 'gl/m4/malloc.m4')
| -rw-r--r-- | gl/m4/malloc.m4 | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/gl/m4/malloc.m4 b/gl/m4/malloc.m4 new file mode 100644 index 0000000..6b76c1e --- /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 + ]) +]) |