diff options
Diffstat (limited to 'src/backend/libpq/pqcomm.c')
| -rw-r--r-- | src/backend/libpq/pqcomm.c | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c index b99c9da2ab5..f4e69742524 100644 --- a/src/backend/libpq/pqcomm.c +++ b/src/backend/libpq/pqcomm.c @@ -30,7 +30,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/libpq/pqcomm.c,v 1.201 2010/01/10 14:16:07 mha Exp $ + * $PostgreSQL: pgsql/src/backend/libpq/pqcomm.c,v 1.202 2010/01/15 09:19:02 heikki Exp $ * *------------------------------------------------------------------------- */ @@ -55,6 +55,7 @@ * pq_peekbyte - peek at next byte from connection * pq_putbytes - send bytes to connection (not flushed until pq_flush) * pq_flush - flush pending output + * pq_getbyte_if_available - get a byte if available without blocking * * message-level I/O (and old-style-COPY-OUT cruft): * pq_putmessage - send a normal message (suppressed in COPY OUT mode) @@ -815,6 +816,56 @@ pq_peekbyte(void) return (unsigned char) PqRecvBuffer[PqRecvPointer]; } + +/* -------------------------------- + * pq_getbyte_if_available - get a single byte from connection, + * if available + * + * The received byte is stored in *c. Returns 1 if a byte was read, 0 if + * if no data was available, or EOF. + * -------------------------------- + */ +int +pq_getbyte_if_available(unsigned char *c) +{ + int r; + + if (PqRecvPointer < PqRecvLength) + { + *c = PqRecvBuffer[PqRecvPointer++]; + return 1; + } + + /* Temporarily put the socket into non-blocking mode */ + if (!pg_set_noblock(MyProcPort->sock)) + ereport(ERROR, + (errmsg("couldn't put socket to non-blocking mode: %m"))); + MyProcPort->noblock = true; + PG_TRY(); + { + r = secure_read(MyProcPort, c, 1); + } + PG_CATCH(); + { + /* + * The rest of the backend code assumes the socket is in blocking + * mode, so treat failure as FATAL. + */ + if (!pg_set_block(MyProcPort->sock)) + ereport(FATAL, + (errmsg("couldn't put socket to blocking mode: %m"))); + MyProcPort->noblock = false; + PG_RE_THROW(); + } + PG_END_TRY(); + if (!pg_set_block(MyProcPort->sock)) + ereport(FATAL, + (errmsg("couldn't put socket to blocking mode: %m"))); + MyProcPort->noblock = false; + + return r; +} + /* -------------------------------- * pq_getbytes - get a known number of bytes from connection * |