283 lines
6.5 KiB
C
283 lines
6.5 KiB
C
/*
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* This file is part of the libpayload project.
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*
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* Copyright (C) 2008 Advanced Micro Devices, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* This is a classically weak malloc() implementation. We have a relatively
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* small and static heap, so we take the easy route with an O(N) loop
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* through the tree for every malloc() and free(). Obviously, this doesn't
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* scale past a few hundred KB (if that).
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*
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* We're also susceptible to the usual buffer overrun poisoning, though the
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* risk is within acceptable ranges for this implementation (don't overrun
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* your buffers, kids!).
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*/
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#include <libpayload.h>
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extern char _heap, _eheap; /* Defined in the ldscript. */
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static void *hstart = (void *)&_heap;
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static void *hend = (void *)&_eheap;
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typedef unsigned int hdrtype_t;
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#define MAGIC (0x2a << 26)
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#define FLAG_FREE (1 << 25)
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#define FLAG_USED (1 << 24)
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#define SIZE(_h) ((_h) & 0xFFFFFF)
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#define _HEADER(_s, _f) ((hdrtype_t) (MAGIC | (_f) | ((_s) & 0xFFFFFF)))
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#define FREE_BLOCK(_s) _HEADER(_s, FLAG_FREE)
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#define USED_BLOCK(_s) _HEADER(_s, FLAG_USED)
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#define HDRSIZE (sizeof(hdrtype_t))
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#define IS_FREE(_h) (((_h) & (MAGIC | FLAG_FREE)) == (MAGIC | FLAG_FREE))
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#define HAS_MAGIC(_h) (((_h) & MAGIC) == MAGIC)
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void print_malloc_map(void);
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static void setup(void)
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{
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int size = (unsigned int)(&_eheap - &_heap) - HDRSIZE;
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*((hdrtype_t *) hstart) = FREE_BLOCK(size);
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}
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static void *alloc(int len, int align)
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{
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hdrtype_t header;
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void *ptr = hstart;
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/* Align the size. */
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len = (len + 3) & ~3;
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if (!len || len > 0xffffff)
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return (void *)NULL;
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/* Make sure the region is setup correctly. */
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if (!HAS_MAGIC(*((hdrtype_t *) ptr)))
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setup();
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/* Find some free space. */
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do {
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header = *((hdrtype_t *) ptr);
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int size = SIZE(header);
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if (!HAS_MAGIC(header)) {
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printf("memory allocator panic.\n");
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halt();
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}
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if (header & FLAG_FREE) {
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int realaddr = (int)(ptr + HDRSIZE);
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int overhead = ((realaddr+align-1) & ~(align-1)) - realaddr;
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if (len + overhead <= size) {
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if (overhead != 0) {
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*((hdrtype_t *) ptr) = FREE_BLOCK(overhead - HDRSIZE);
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ptr += overhead;
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size -= overhead;
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}
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void *nptr = ptr + (HDRSIZE + len);
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int nsize = size - (HDRSIZE + len);
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/* Mark the block as used. */
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*((hdrtype_t *) ptr) = USED_BLOCK(len);
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/* If there is still room in this block,
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* then mark it as such.
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*/
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if (nsize > 0)
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*((hdrtype_t *) nptr) =
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FREE_BLOCK(nsize);
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return (void *)(ptr + HDRSIZE);
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}
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}
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ptr += HDRSIZE + size;
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} while (ptr < hend);
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/* Nothing available. */
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return (void *)NULL;
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}
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static void _consolidate(void)
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{
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void *ptr = hstart;
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while (ptr < hend) {
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void *nptr;
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hdrtype_t hdr = *((hdrtype_t *) ptr);
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unsigned int size = 0;
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if (!IS_FREE(hdr)) {
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ptr += HDRSIZE + SIZE(hdr);
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continue;
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}
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size = SIZE(hdr);
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nptr = ptr + HDRSIZE + SIZE(hdr);
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while (nptr < hend) {
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hdrtype_t nhdr = *((hdrtype_t *) nptr);
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if (!(IS_FREE(nhdr)))
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break;
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size += SIZE(nhdr) + HDRSIZE;
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*((hdrtype_t *) nptr) = 0;
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nptr += (HDRSIZE + SIZE(nhdr));
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}
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*((hdrtype_t *) ptr) = FREE_BLOCK(size);
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ptr = nptr;
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}
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}
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void free(void *ptr)
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{
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hdrtype_t hdr;
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ptr -= HDRSIZE;
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/* Sanity check. */
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if (ptr < hstart || ptr >= hend)
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return;
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hdr = *((hdrtype_t *) ptr);
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/* Not our header (we're probably poisoned). */
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if (!HAS_MAGIC(hdr))
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return;
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/* Double free. */
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if (hdr & FLAG_FREE)
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return;
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*((hdrtype_t *) ptr) = FREE_BLOCK(SIZE(hdr));
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_consolidate();
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}
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void *malloc(size_t size)
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{
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return alloc(size, 1);
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}
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void *calloc(size_t nmemb, size_t size)
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{
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size_t total = nmemb * size;
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void *ptr = alloc(total, 1);
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if (ptr)
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memset(ptr, 0, total);
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return ptr;
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}
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void *realloc(void *ptr, size_t size)
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{
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void *ret, *pptr;
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unsigned int osize;
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if (ptr == NULL)
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return alloc(size, 1);
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pptr = ptr - HDRSIZE;
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if (!HAS_MAGIC(*((hdrtype_t *) pptr)))
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return NULL;
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/* Get the original size of the block. */
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osize = SIZE(*((hdrtype_t *) pptr));
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/*
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* Free the memory to update the tables - this won't touch the actual
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* memory, so we can still use it for the copy after we have
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* reallocated the new space.
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*/
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free(ptr);
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ret = alloc(size, 1);
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/*
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* if ret == NULL, then doh - failure.
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* if ret == ptr then woo-hoo! no copy needed.
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*/
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if (ret == NULL || ret == ptr)
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return ret;
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/* Copy the memory to the new location. */
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memcpy(ret, ptr, osize > size ? size : osize);
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return ret;
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}
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/**
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* Allocate an aligned chunk of memory
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*
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* @param align alignment, must be power of two
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* @param size size of chunk in bytes
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* @return Return the address of such a memory region or NULL
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*/
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void *memalign(size_t align, size_t size)
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{
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return alloc(size, align);
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}
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/* This is for debugging purposes. */
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#ifdef TEST
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void print_malloc_map(void)
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{
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void *ptr = hstart;
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while (ptr < hend) {
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hdrtype_t hdr = *((hdrtype_t *) ptr);
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if (!HAS_MAGIC(hdr)) {
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printf("Poisoned magic - we're toast\n");
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break;
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}
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/* FIXME: Verify the size of the block. */
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printf("%x: %s (%x bytes)\n",
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(unsigned int)(ptr - hstart),
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hdr & FLAG_FREE ? "FREE" : "USED", SIZE(hdr));
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ptr += HDRSIZE + SIZE(hdr);
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}
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}
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#endif
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