/*
* The actual free() implementation.
*/
void
free(void *x)
{
struct mheader *mh, *mhnext, *mhprev;
if (x==NULL) {
/* safest practice */
return;
}
/* Consistency check. */
if (__heapbase==0 || __heaptop==0 || __heapbase > __heaptop) {
warnx("free: Internal error - local data corrupt");
errx(1, "free: heapbase 0x%lx; heaptop 0x%lx",
(unsigned long) __heapbase, (unsigned long) __heaptop);
}
/* Don't allow freeing pointers that aren't on the heap. */
if ((uintptr_t)x < __heapbase || (uintptr_t)x >= __heaptop) {
errx(1, "free: Invalid pointer %p freed (out of range)", x);
}
#ifdef MALLOCDEBUG
warnx("free: about to free %p", x);
__malloc_dump();
#endif
mh = ((struct mheader *)x)-1;
if (!M_OK(mh)) {
errx(1, "free: Invalid pointer %p freed (corrupt header)", x);
}
if (!mh->mh_inuse) {
errx(1, "free: Invalid pointer %p freed (already free)", x);
}
/* mark it free */
mh->mh_inuse = 0;
/* wipe it */
__malloc_deadbeef(M_DATA(mh), M_SIZE(mh));
/* Try merging with the block above (but not if we're at the top) */
mhnext = M_NEXT(mh);
if (mhnext != (struct mheader *)__heaptop) {
__malloc_trymerge(mh, mhnext);
}
/* Try merging with the block below (but not if we're at the bottom) */
if (mh != (struct mheader *)__heapbase) {
mhprev = M_PREV(mh);
__malloc_trymerge(mhprev, mh);
}
#ifdef MALLOCDEBUG
warnx("free: freed %p", x);
__malloc_dump();
#endif
}
/*
* malloc: general-purpose storage allocator
*/
void *
malloc(size_t nbytes)
{
Header *p, *prevp;
unsigned nunits;
nunits = (nbytes + sizeof(Header) - 1) / sizeof(Header) + 1;
MALLOC_LOCK;
if ((prevp = freep) == NULL) { /* no free list yet */
base.s.ptr = freep = prevp = &base;
base.s.size = 0;
}
for (p = prevp->s.ptr;; prevp = p, p = p->s.ptr) {
if (p->s.size >= nunits) { /* big enough */
if (p->s.size == nunits) /* exactly */
prevp->s.ptr = p->s.ptr;
else { /* allocate tail end */
p->s.size -= nunits;
p += p->s.size;
p->s.size = nunits;
}
freep = prevp;
#ifdef CONFIG_MALLOC_DEBUG
{
/* Write bit pattern over data */
char *x = (char *) (p + 1);
int i;
for (i = 0; i < nbytes; i++)
x[i] = 0xd0;
}
#endif
#ifdef CONFIG_MALLOC_INSTRUMENT
__malloc_instrumented_allocated += nunits;
#endif
#ifdef CONFIG_MALLOC_DEBUG_INTERNAL
if (__malloc_check() != 0) {
printf("malloc %d %p\n", nbytes, (void *) (p + 1));
__malloc_dump();
assert(__malloc_check() == 0);
}
#endif
MALLOC_UNLOCK;
return (void *) (p + 1);
}
if (p == freep) { /* wrapped around free list */
if ((p = (Header *) morecore(nunits)) == NULL) {
MALLOC_UNLOCK;
return NULL; /* none left */
} else {
p->s.ptr = p;
}
}
}
MALLOC_UNLOCK;
}
/*
* free: put block ap in free list
*/
void
free(void *ap)
{
Header *bp, *p;
if (ap == NULL)
return;
MALLOC_LOCK;
bp = (Header *) ap - 1; /* point to block header */
for (p = freep; !(bp > p && bp < p->s.ptr); p = p->s.ptr)
if (p >= p->s.ptr && (bp > p || bp < p->s.ptr))
break; /* freed block at start or end of arena */
#ifdef CONFIG_MALLOC_INSTRUMENT
__malloc_instrumented_allocated -= bp->s.size;
#endif
if (bp + bp->s.size == p->s.ptr) { /* join to upper nbr */
bp->s.size += p->s.ptr->s.size;
bp->s.ptr = p->s.ptr->s.ptr;
} else {
bp->s.ptr = p->s.ptr;
}
if (p + p->s.size == bp) { /* join to lower nbr */
p->s.size += bp->s.size;
p->s.ptr = bp->s.ptr;
} else {
p->s.ptr = bp;
}
freep = p;
#ifdef CONFIG_MALLOC_DEBUG_INTERNAL
if (__malloc_check() != 0) {
printf("free %p\n", ap);
__malloc_dump();
assert(__malloc_check() == 0);
}
#endif
MALLOC_UNLOCK;
}
/*
* malloc itself.
*/
void *
malloc(size_t size)
{
struct mheader *mh;
uintptr_t i;
size_t rightprevblock;
if (__heapbase==0) {
__malloc_init();
}
if (__heapbase==0 || __heaptop==0 || __heapbase > __heaptop) {
warnx("malloc: Internal error - local data corrupt");
errx(1, "malloc: heapbase 0x%lx; heaptop 0x%lx",
(unsigned long) __heapbase, (unsigned long) __heaptop);
}
#ifdef MALLOCDEBUG
warnx("malloc: about to allocate %lu (0x%lx) bytes",
(unsigned long) size, (unsigned long) size);
__malloc_dump();
#endif
/* Round size up to an integral number of blocks. */
size = ((size + MBLOCKSIZE - 1) & ~(size_t)(MBLOCKSIZE-1));
/*
* First-fit search algorithm for available blocks.
* Check to make sure the next/previous sizes all agree.
*/
rightprevblock = 0;
for (i=__heapbase; i<__heaptop; i += M_NEXTOFF(mh)) {
mh = (struct mheader *) i;
if (!M_OK(mh)) {
errx(1, "malloc: Heap corrupt; header at 0x%lx"
" has bad magic bits",
(unsigned long) i);
}
if (mh->mh_prevblock != rightprevblock) {
errx(1, "malloc: Heap corrupt; header at 0x%lx"
" has bad previous-block size %lu "
"(should be %lu)",
(unsigned long) i,
(unsigned long) mh->mh_prevblock << MBLOCKSHIFT,
(unsigned long) rightprevblock << MBLOCKSHIFT);
}
rightprevblock = mh->mh_nextblock;
/* Can't allocate a block that's in use. */
if (mh->mh_inuse) {
continue;
}
/* Can't allocate a block that isn't big enough. */
if (M_SIZE(mh) < size) {
continue;
}
/* Try splitting block. */
__malloc_split(mh, size);
/*
* Now, allocate.
*/
mh->mh_inuse = 1;
#ifdef MALLOCDEBUG
warnx("malloc: allocating at %p", M_DATA(mh));
__malloc_dump();
#endif
return M_DATA(mh);
}
if (i!=__heaptop) {
errx(1, "malloc: Heap corrupt; ran off end");
}
/*
* Didn't find anything. Expand the heap.
*/
mh = __malloc_sbrk(size + MBLOCKSIZE);
if (mh == NULL) {
return NULL;
}
mh->mh_prevblock = rightprevblock;
mh->mh_magic1 = MMAGIC;
mh->mh_magic2 = MMAGIC;
mh->mh_pad = 0;
mh->mh_inuse = 1;
mh->mh_nextblock = M_MKFIELD(size + MBLOCKSIZE);
#ifdef MALLOCDEBUG
warnx("malloc: allocating at %p", M_DATA(mh));
__malloc_dump();
#endif
return M_DATA(mh);
}