Обсуждение: pgsql: Fix snapshot leak if lo_open called on non-existent object.

Fix snapshot leak if lo_open called on non-existent object.

lo_open registers the currently active snapshot, and checks if the
large object exists after that. Normally, snapshots registered by lo_open
are unregistered at end of transaction when the lo descriptor is closed, but
if we error out before the lo descriptor is added to the list of open
descriptors, it is leaked. Fix by moving the snapshot registration to after
checking if the large object exists.

Reported by Pavel Stehule. Backpatch to 8.4. The snapshot registration
system was introduced in 8.4, so prior versions are not affected (and not
supported, anyway).

Branch
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REL8_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/fef01d4199f18a9ccc5748fdc9ee44720d3a97c8

Modified Files
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src/backend/storage/large_object/inv_api.c |   44 ++++++++++++++++------------
1 file changed, 26 insertions(+), 18 deletions(-)