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Improve inv_getsize() per suggestion from Denis Perchine; also fix

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thinkos in inv_seek().
This commit is contained in:
Tom Lane 2000-11-02 23:52:06 +00:00
parent db263da468
commit 94d8bbe5fb
1 changed files with 16 additions and 11 deletions
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27
src/backend/storage/large_object/inv_api.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.79 2000/10/24 01:38:29 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.80 2000/11/02 23:52:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -186,7 +186,6 @@ inv_getsize(LargeObjectDesc *obj_desc)
{
bool found = false;
uint32 lastbyte = 0;
uint32 thislastbyte;
ScanKeyData skey[1];
IndexScanDesc sd;
RetrieveIndexResult indexRes;
@ -209,7 +208,13 @@ inv_getsize(LargeObjectDesc *obj_desc)
tuple.t_datamcxt = CurrentMemoryContext;
tuple.t_data = NULL;
while ((indexRes = index_getnext(sd, ForwardScanDirection)))
/*
* Because the pg_largeobject index is on both loid and pageno,
* but we constrain only loid, a backwards scan should visit all
* pages of the large object in reverse pageno order. So, it's
* sufficient to examine the first valid tuple (== last valid page).
*/
while ((indexRes = index_getnext(sd, BackwardScanDirection)))
{
tuple.t_self = indexRes->heap_iptr;
heap_fetch(obj_desc->heap_r, SnapshotNow, &tuple, &buffer);
@ -226,12 +231,11 @@ inv_getsize(LargeObjectDesc *obj_desc)
heap_tuple_untoast_attr((varattrib *) datafield);
pfreeit = true;
}
thislastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield);
if (thislastbyte > lastbyte)
lastbyte = thislastbyte;
lastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield);
if (pfreeit)
pfree(datafield);
ReleaseBuffer(buffer);
break;
}
index_endscan(sd);
@ -254,16 +258,17 @@ inv_seek(LargeObjectDesc *obj_desc, int offset, int whence)
obj_desc->offset = offset;
break;
case SEEK_CUR:
if ((obj_desc->offset + offset) < 0)
if (offset < 0 && obj_desc->offset < ((uint32) (- offset)))
elog(ERROR, "inv_seek: invalid offset: %d", offset);
obj_desc->offset += offset;
break;
case SEEK_END:
{
uint32 size = inv_getsize(obj_desc);
if (offset < 0 || ((uint32) offset) > size)
elog(ERROR, "inv_seek: invalid offset");
obj_desc->offset = size - offset;
uint32 size = inv_getsize(obj_desc);
if (offset < 0 && size < ((uint32) (- offset)))
elog(ERROR, "inv_seek: invalid offset: %d", offset);
obj_desc->offset = size + offset;
}
break;
default: