+++ /dev/null
-/* -*- buffer-read-only: t -*- vi: set ro: */
-/* DO NOT EDIT! GENERATED AUTOMATICALLY! */
-/* Safe automatic memory allocation.
- Copyright (C) 2003, 2006-2007 Free Software Foundation, Inc.
- Written by Bruno Haible <bruno@clisp.org>, 2003.
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
-
-#include <config.h>
-
-/* Specification. */
-#include "malloca.h"
-
-/* The speed critical point in this file is freea() applied to an alloca()
- result: it must be fast, to match the speed of alloca(). The speed of
- mmalloca() and freea() in the other case are not critical, because they
- are only invoked for big memory sizes. */
-
-#if HAVE_ALLOCA
-
-/* Store the mmalloca() results in a hash table. This is needed to reliably
- distinguish a mmalloca() result and an alloca() result.
-
- Although it is possible that the same pointer is returned by alloca() and
- by mmalloca() at different times in the same application, it does not lead
- to a bug in freea(), because:
- - Before a pointer returned by alloca() can point into malloc()ed memory,
- the function must return, and once this has happened the programmer must
- not call freea() on it anyway.
- - Before a pointer returned by mmalloca() can point into the stack, it
- must be freed. The only function that can free it is freea(), and
- when freea() frees it, it also removes it from the hash table. */
-
-#define MAGIC_NUMBER 0x1415fb4a
-#define MAGIC_SIZE sizeof (int)
-/* This is how the header info would look like without any alignment
- considerations. */
-struct preliminary_header { void *next; char room[MAGIC_SIZE]; };
-/* But the header's size must be a multiple of sa_alignment_max. */
-#define HEADER_SIZE \
- (((sizeof (struct preliminary_header) + sa_alignment_max - 1) / sa_alignment_max) * sa_alignment_max)
-struct header { void *next; char room[HEADER_SIZE - sizeof (struct preliminary_header) + MAGIC_SIZE]; };
-/* Verify that HEADER_SIZE == sizeof (struct header). */
-typedef int verify1[2 * (HEADER_SIZE == sizeof (struct header)) - 1];
-/* We make the hash table quite big, so that during lookups the probability
- of empty hash buckets is quite high. There is no need to make the hash
- table resizable, because when the hash table gets filled so much that the
- lookup becomes slow, it means that the application has memory leaks. */
-#define HASH_TABLE_SIZE 257
-static void * mmalloca_results[HASH_TABLE_SIZE];
-
-#endif
-
-void *
-mmalloca (size_t n)
-{
-#if HAVE_ALLOCA
- /* Allocate one more word, that serves as an indicator for malloc()ed
- memory, so that freea() of an alloca() result is fast. */
- size_t nplus = n + HEADER_SIZE;
-
- if (nplus >= n)
- {
- char *p = (char *) malloc (nplus);
-
- if (p != NULL)
- {
- size_t slot;
-
- p += HEADER_SIZE;
-
- /* Put a magic number into the indicator word. */
- ((int *) p)[-1] = MAGIC_NUMBER;
-
- /* Enter p into the hash table. */
- slot = (unsigned long) p % HASH_TABLE_SIZE;
- ((struct header *) (p - HEADER_SIZE))->next = mmalloca_results[slot];
- mmalloca_results[slot] = p;
-
- return p;
- }
- }
- /* Out of memory. */
- return NULL;
-#else
-# if !MALLOC_0_IS_NONNULL
- if (n == 0)
- n = 1;
-# endif
- return malloc (n);
-#endif
-}
-
-#if HAVE_ALLOCA
-void
-freea (void *p)
-{
- /* mmalloca() may have returned NULL. */
- if (p != NULL)
- {
- /* Attempt to quickly distinguish the mmalloca() result - which has
- a magic indicator word - and the alloca() result - which has an
- uninitialized indicator word. It is for this test that sa_increment
- additional bytes are allocated in the alloca() case. */
- if (((int *) p)[-1] == MAGIC_NUMBER)
- {
- /* Looks like a mmalloca() result. To see whether it really is one,
- perform a lookup in the hash table. */
- size_t slot = (unsigned long) p % HASH_TABLE_SIZE;
- void **chain = &mmalloca_results[slot];
- for (; *chain != NULL;)
- {
- if (*chain == p)
- {
- /* Found it. Remove it from the hash table and free it. */
- char *p_begin = (char *) p - HEADER_SIZE;
- *chain = ((struct header *) p_begin)->next;
- free (p_begin);
- return;
- }
- chain = &((struct header *) ((char *) *chain - HEADER_SIZE))->next;
- }
- }
- /* At this point, we know it was not a mmalloca() result. */
- }
-}
-#endif
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