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memorypool: reallocate: more checks for value wrap, small optimization

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This commit is contained in:
Evgeny Grin (Karlson2k)
2019-06-13 19:16:51 +03:00
parent 35d581d04f
commit d12ed49fd3
1 changed files with 18 additions and 14 deletions
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src/microhttpd/memorypool.c
+18 -14
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@@ -267,29 +267,33 @@ MHD_pool_reallocate (struct MemoryPool *pool,
/* Blocks "from the end" must not be reallocated */
mhd_assert (old == NULL || pool->memory + pool->pos > (uint8_t*)old);
if (new_size + 2 * ALIGN_SIZE < new_size)
return NULL; /* Value wrap, too large new_size. */
if (0 != old_size)
{ /* Need to relocate data */
{ /* Need to save some data */
const size_t old_offset = (uint8_t*)old - pool->memory;
/* Try resizing in-place */
if (pool->pos == ROUND_TO_ALIGN (old_offset + old_size))
{ /* "old" block is the last allocated block */
const size_t new_apos = ROUND_TO_ALIGN (old_offset + new_size);
if (new_apos > pool->end)
return NULL; /* No space */
pool->pos = new_apos;
/* Zero-out unused part if shrinking */
if (old_size > new_size)
memset ((uint8_t*)old + new_size, 0, old_size - new_size);
{ /* Shrinking in-place, zero-out freed part */
memset ((uint8_t*)old + new_size, 0, old_size - new_size);
}
else
{ /* Grow in-place, check for enough space. */
if ( (new_apos > pool->end) ||
(new_apos < pool->pos) ) /* Value wrap */
return NULL; /* No space */
}
/* Resized in-place */
pool->pos = new_apos;
return old;
}
}
/* Need to allocate new block */
asize = ROUND_TO_ALIGN (new_size);
if (asize > pool->end - pool->pos)
if ( ( (0 == asize) &&
(0 != new_size) ) || /* Value wrap, too large new_size. */
(asize > pool->end - pool->pos) )
return NULL; /* No space */
new_blc = pool->memory + pool->pos;
@@ -297,9 +301,9 @@ MHD_pool_reallocate (struct MemoryPool *pool,
if (0 != old_size)
{
/* Move data no new block, old block remains allocated */
/* Move data to new block, old block remains allocated */
memcpy (new_blc, old, old_size);
/* Zero-out old block */
/* Zero-out freed old block */
memset (old, 0, old_size);
}
return new_blc;