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Zero padding byte at end of GIN posting list.

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This isn't strictly necessary, but helps debugging.
This commit is contained in:
Heikki Linnakangas 2014-04-07 19:48:03 +03:00
parent f235db03ff
commit 38a2b95c34
1 changed files with 13 additions and 0 deletions
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13
src/backend/access/gin/ginpostinglist.c
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@ -176,6 +176,9 @@ decode_varbyte(unsigned char **ptr)
* 'maxsize' bytes in size. The number items in the returned segment is * 'maxsize' bytes in size. The number items in the returned segment is
* returned in *nwritten. If it's not equal to nipd, not all the items fit * returned in *nwritten. If it's not equal to nipd, not all the items fit
* in 'maxsize', and only the first *nwritten were encoded. * in 'maxsize', and only the first *nwritten were encoded.
*
* The allocated size of the returned struct is short-aligned, and the padding
* byte at the end, if any, is zero.
*/ */
GinPostingList * GinPostingList *
ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize, ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize,
@ -188,9 +191,12 @@ ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize,
unsigned char *ptr; unsigned char *ptr;
unsigned char *endptr; unsigned char *endptr;
maxsize = SHORTALIGN_DOWN(maxsize);
result = palloc(maxsize); result = palloc(maxsize);
maxbytes = maxsize - offsetof(GinPostingList, bytes); maxbytes = maxsize - offsetof(GinPostingList, bytes);
Assert(maxbytes > 0);
/* Store the first special item */ /* Store the first special item */
result->first = ipd[0]; result->first = ipd[0];
@ -228,6 +234,13 @@ ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize,
} }
result->nbytes = ptr - result->bytes; result->nbytes = ptr - result->bytes;
/*
* If we wrote an odd number of bytes, zero out the padding byte at the
* end.
*/
if (result->nbytes != SHORTALIGN(result->nbytes))
result->bytes[result->nbytes] = 0;
if (nwritten) if (nwritten)
*nwritten = totalpacked; *nwritten = totalpacked;