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pool: avoid triggering assert(b->magic != FREE_MAGIC) in blocksetsize() for mallocalignl()

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when we trim the front of a block with freefromfront(),
the block magic of the back was not initialized which
could sometimes trigger the assert in blocksetsize()
to fail. fix is to just move the initialization of the
magic field before the blocksetsize() call.

the second b->magic = UNALLOC_MAGIC isnt really required
but just done for consistency with the trim() code above.
This commit is contained in:
cinap_lenrek 2015-04-08 21:04:10 +02:00
parent adfb8dff26
commit ca4e12839a
1 changed files with 2 additions and 2 deletions
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4
sys/src/libc/port/pool.c
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@ -520,10 +520,10 @@ freefromfront(Pool *p, Alloc *b, ulong skip)
skip = skip&~(p->quantum-1);
if(skip >= 0x1000 || (skip >= b->size>>2 && skip >= MINBLOCKSIZE && skip >= p->minblock)){
bb = (Alloc*)((uchar*)b+skip);
blocksetsize(bb, b->size-skip);
bb->magic = UNALLOC_MAGIC;
blocksetsize(b, skip);
blocksetsize(bb, b->size-skip);
b->magic = UNALLOC_MAGIC;
blocksetsize(b, skip);
pooladd(p, b);
return bb;
}