void AllocPool::DoCheckFreeChunk(AllocChunkPtr p)
{
size_t size = p->Size();
#ifndef NDEBUG
AllocChunkPtr next = p->ChunkAtOffset(size);
#endif
DoCheckChunk(p);
/* Check whether it claims to be free ... */
assert(!p->InUse());
/* Unless an end marker, must have OK fields */
if (size >= kMinAllocSize)
{
assert((size & kAlignMask) == 0);
assert(aligned_OK(p->ToPtr()));
/* ... and is fully consolidated */
assert(p->PrevInUse());
assert(next->InUse());
/* ... and has minimally sane links */
assert(p->Next()->Prev() == p);
assert(p->Prev()->Next() == p);
}
else /* end markers are always of size 0 */
assert(size == 0);
}
static mchunkptr
internal_function
mem2chunk_check(void* mem, unsigned char **magic_p)
{
mchunkptr p;
INTERNAL_SIZE_T sz, c;
unsigned char magic;
if(!aligned_OK(mem)) return NULL;
p = mem2chunk(mem);
if (!chunk_is_mmapped(p)) {
/* Must be a chunk in conventional heap memory. */
int contig = contiguous(&main_arena);
sz = chunksize(p);
if((contig &&
((char*)p<mp_.sbrk_base ||
((char*)p + sz)>=(mp_.sbrk_base+main_arena.system_mem) )) ||
sz<MINSIZE || sz&MALLOC_ALIGN_MASK || !inuse(p) ||
( !prev_inuse(p) && (p->prev_size&MALLOC_ALIGN_MASK ||
(contig && (char*)prev_chunk(p)<mp_.sbrk_base) ||
next_chunk(prev_chunk(p))!=p) ))
return NULL;
magic = MAGICBYTE(p);
for(sz += SIZE_SZ-1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
} else {
unsigned long offset, page_mask = GLRO(dl_pagesize)-1;
/* mmap()ed chunks have MALLOC_ALIGNMENT or higher power-of-two
alignment relative to the beginning of a page. Check this
first. */
offset = (unsigned long)mem & page_mask;
if((offset!=MALLOC_ALIGNMENT && offset!=0 && offset!=0x10 &&
offset!=0x20 && offset!=0x40 && offset!=0x80 && offset!=0x100 &&
offset!=0x200 && offset!=0x400 && offset!=0x800 && offset!=0x1000 &&
offset<0x2000) ||
!chunk_is_mmapped(p) || (p->size & PREV_INUSE) ||
( (((unsigned long)p - p->prev_size) & page_mask) != 0 ) ||
( (sz = chunksize(p)), ((p->prev_size + sz) & page_mask) != 0 ) )
return NULL;
magic = MAGICBYTE(p);
for(sz -= 1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
}
((unsigned char*)p)[sz] ^= 0xFF;
if (magic_p)
*magic_p = (unsigned char *)p + sz;
return p;
}
void AllocPool::DoCheckAllocedChunk(AllocChunkPtr p, size_t s)
{
#ifndef NDEBUG
size_t size = p->Size();
long room = size - s;
#endif
DoCheckInUseChunk(p);
/* Legal size ... */
assert(size >= kMinAllocSize);
assert((size & kAlignMask) == 0);
assert(room >= 0);
assert(room < kMinAllocSize);
/* ... and alignment */
assert(aligned_OK(p->ToPtr()));
/* ... and was allocated at front of an available chunk */
assert(p->PrevInUse()); // huh?? - jmc
}
/* ------------------------------ realloc ------------------------------ */
void* ulibc_realloc(void* oldmem, size_t bytes)
{
mstate av;
size_t nb; /* padded request size */
mchunkptr oldp; /* chunk corresponding to oldmem */
size_t oldsize; /* its size */
mchunkptr newp; /* chunk to return */
size_t newsize; /* its size */
void* newmem; /* corresponding user mem */
mchunkptr next; /* next contiguous chunk after oldp */
mchunkptr remainder; /* extra space at end of newp */
unsigned long remainder_size; /* its size */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
unsigned long copysize; /* bytes to copy */
unsigned int ncopies; /* size_t words to copy */
size_t* s; /* copy source */
size_t* d; /* copy destination */
void *retval;
/* Check for special cases. */
if (! oldmem)
return ulibc_malloc(bytes);
if (! bytes) {
ulibc_free (oldmem);
return NULL;
}
av = get_malloc_state();
checked_request2size(bytes, nb);
oldp = mem2chunk(oldmem);
oldsize = chunksize(oldp);
check_inuse_chunk(oldp);
if (!chunk_is_mmapped(oldp)) {
if ((unsigned long)(oldsize) >= (unsigned long)(nb)) {
/* already big enough; split below */
newp = oldp;
newsize = oldsize;
}
else {
next = chunk_at_offset(oldp, oldsize);
/* Try to expand forward into top */
if (next == av->top &&
(unsigned long)(newsize = oldsize + chunksize(next)) >=
(unsigned long)(nb + MINSIZE)) {
set_head_size(oldp, nb);
av->top = chunk_at_offset(oldp, nb);
set_head(av->top, (newsize - nb) | PREV_INUSE);
retval = chunk2mem(oldp);
goto DONE;
}
/* Try to expand forward into next chunk; split off remainder below */
else if (next != av->top &&
!inuse(next) &&
(unsigned long)(newsize = oldsize + chunksize(next)) >=
(unsigned long)(nb)) {
newp = oldp;
unlink(next, bck, fwd);
}
/* allocate, copy, free */
else {
newmem = malloc(nb - MALLOC_ALIGN_MASK);
if (newmem == 0) {
retval = 0; /* propagate failure */
goto DONE;
}
newp = mem2chunk(newmem);
newsize = chunksize(newp);
/*
Avoid copy if newp is next chunk after oldp.
*/
if (newp == next) {
newsize += oldsize;
newp = oldp;
}
else {
/*
Unroll copy of <= 36 bytes (72 if 8byte sizes)
We know that contents have an odd number of
size_t-sized words; minimally 3.
*/
copysize = oldsize - (sizeof(size_t));
s = (size_t*)(oldmem);
d = (size_t*)(newmem);
ncopies = copysize / sizeof(size_t);
assert(ncopies >= 3);
if (ncopies > 9)
memcpy(d, s, copysize);
else {
*(d+0) = *(s+0);
*(d+1) = *(s+1);
*(d+2) = *(s+2);
if (ncopies > 4) {
*(d+3) = *(s+3);
*(d+4) = *(s+4);
if (ncopies > 6) {
*(d+5) = *(s+5);
*(d+6) = *(s+6);
if (ncopies > 8) {
*(d+7) = *(s+7);
*(d+8) = *(s+8);
}
}
}
}
ulibc_free(oldmem);
check_inuse_chunk(newp);
retval = chunk2mem(newp);
goto DONE;
}
}
}
/* If possible, free extra space in old or extended chunk */
assert((unsigned long)(newsize) >= (unsigned long)(nb));
remainder_size = newsize - nb;
if (remainder_size < MINSIZE) { /* not enough extra to split off */
set_head_size(newp, newsize);
set_inuse_bit_at_offset(newp, newsize);
}
else { /* split remainder */
remainder = chunk_at_offset(newp, nb);
set_head_size(newp, nb);
set_head(remainder, remainder_size | PREV_INUSE);
/* Mark remainder as inuse so free() won't complain */
set_inuse_bit_at_offset(remainder, remainder_size);
ulibc_free(chunk2mem(remainder));
}
check_inuse_chunk(newp);
retval = chunk2mem(newp);
goto DONE;
}
/*
Handle mmap cases
*/
else {
size_t offset = oldp->prev_size;
size_t pagemask = av->pagesize - 1;
char *cp;
unsigned long sum;
/* Note the extra (sizeof(size_t)) overhead */
newsize = (nb + offset + (sizeof(size_t)) + pagemask) & ~pagemask;
/* don't need to remap if still within same page */
if (oldsize == newsize - offset) {
retval = oldmem;
goto DONE;
}
cp = (char*)mremap((char*)oldp - offset, oldsize + offset, newsize, 1);
if (cp != (char*)MORECORE_FAILURE) {
newp = (mchunkptr)(cp + offset);
set_head(newp, (newsize - offset)|IS_MMAPPED);
assert(aligned_OK(chunk2mem(newp)));
assert((newp->prev_size == offset));
/* update statistics */
sum = av->mmapped_mem += newsize - oldsize;
if (sum > (unsigned long)(av->max_mmapped_mem))
av->max_mmapped_mem = sum;
sum += av->sbrked_mem;
if (sum > (unsigned long)(av->max_total_mem))
av->max_total_mem = sum;
retval = chunk2mem(newp);
goto DONE;
}
/* Note the extra (sizeof(size_t)) overhead. */
if ((unsigned long)(oldsize) >= (unsigned long)(nb + (sizeof(size_t))))
newmem = oldmem; /* do nothing */
else {
/* Must alloc, copy, free. */
newmem = malloc(nb - MALLOC_ALIGN_MASK);
if (newmem != 0) {
memcpy(newmem, oldmem, oldsize - 2*(sizeof(size_t)));
ulibc_free(oldmem);
}
}
retval = newmem;
}
DONE:
return retval;
}
static mchunkptr malloc_from_sys(unsigned nb)
{
mchunkptr p;
size_t sbrk_size;
int* ip;
/* Minimally, we need to pad with enough space */
/* to place dummy size/use fields to ends if needed */
sbrk_size = ((nb + SBRK_UNIT - 1 + SIZE_SZ + SIZE_SZ)
/ SBRK_UNIT) * SBRK_UNIT;
ip = (int*)(sbrk(sbrk_size));
if ((char*)ip == (char*)(-1)) /* sbrk returns -1 on failure */
{
return 0;
}
UPDATE_STATS ((++n_sbrks, sbrked_mem += sbrk_size));
if (last_sbrk_end != &ip[-1])
{
/* It's either first time through or someone else called sbrk. */
/* Arrange end-markers at front & back */
/* Shouldn't be necessary, but better to be safe */
while (!aligned_OK(ip)) { ++ip; sbrk_size -= SIZE_SZ; }
/* Mark the front as in use to prevent merging. */
/* Note we can get away with only 1 word, not MINSIZE overhead here */
*ip++ = SIZE_SZ | INUSE;
p = (mchunkptr)ip;
set_size(p,sbrk_size - (SIZE_SZ + SIZE_SZ));
}
else
{
mchunkptr l;
/* We can safely make the header start at end of prev sbrked chunk. */
/* We will still have space left at the end from a previous call */
/* to place the end marker, below */
p = (mchunkptr)(last_sbrk_end);
set_size(p, sbrk_size);
/* Even better, maybe we can merge with last fragment: */
l = prev_chunk(p);
if (!inuse(l))
{
unlink(l);
set_size(l, p->size + l->size);
p = l;
}
}
/* mark the end of sbrked space as in use to prevent merging */
last_sbrk_end = (int*)((char*)p + p->size);
*last_sbrk_end = SIZE_SZ | INUSE;
UPDATE_STATS((++n_avail, ++n_malloc_chunks));
/* make it safe to unlink in malloc */
UPDATE_STATS(++n_avail);
p->fd = p->bk = p;
return p;
}