[pgpool-committers: 8025] pgpool: Fix occasional hang in COPY FROM.

[Tatsuo Ishii]

Fix occasional hang in COPY FROM.

If an error occurs while doing COPY FROM, it was possible the
Pgpool-II waited forever for a response from backend after COPY end
marker was sent from frontend. Pgpool expected a new message arrives
to socket, but it is possible that the message (in this case an error
message) is already in the backend read buffer. The fix is, check the
buffer is empty or not before reading from the socket.  New test case
(07.copy_hang) is also added.

The bug was found by Bo Peng.

Branch
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V4_1_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=34dd96c950cdacab3cdfcf04c35fce53e5275ff2

Modified Files
--------------
src/protocol/pool_proto_modules.c               | 15 ++++++-
src/test/regression/tests/076.copy_hang/test.sh | 54 +++++++++++++++++++++++++
2 files changed, 67 insertions(+), 2 deletions(-)