fe-protocol2.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		else
			conn->notifyHead = newNotify;
		conn->notifyTail = newNotify;
	}

	return 0;
}


/*
 * PQgetCopyData - read a row of data from the backend during COPY OUT
 *
 * If successful, sets *buffer to point to a malloc'd row of data, and
 * returns row length (always > 0) as result.
 * Returns 0 if no row available yet (only possible if async is true),
 * -1 if end of copy (consult PQgetResult), or -2 if error (consult
 * PQerrorMessage).
 */
int
pqGetCopyData2(PGconn *conn, char **buffer, int async)
{
	bool		found;
	int			msgLength;

	for (;;)
	{
		/*
		 * Do we have a complete line of data?
		 */
		conn->inCursor = conn->inStart;
		found = false;
		while (conn->inCursor < conn->inEnd)
		{
			char		c = conn->inBuffer[conn->inCursor++];

			if (c == '\n')
			{
				found = true;
				break;
			}
		}
		if (!found)
			goto nodata;
		msgLength = conn->inCursor - conn->inStart;

		/*
		 * If it's the end-of-data marker, consume it, exit COPY_OUT mode, and
		 * let caller read status with PQgetResult().
		 */
		if (msgLength == 3 &&
			strncmp(&conn->inBuffer[conn->inStart], "\\.\n", 3) == 0)
		{
			conn->inStart = conn->inCursor;
			conn->asyncStatus = PGASYNC_BUSY;
			return -1;
		}

		/*
		 * Pass the line back to the caller.
		 */
		*buffer = (char *) malloc(msgLength + 1);
		if (*buffer == NULL)
		{
			printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext("out of memory\n"));
			return -2;
		}
		memcpy(*buffer, &conn->inBuffer[conn->inStart], msgLength);
		(*buffer)[msgLength] = '\0';	/* Add terminating null */

		/* Mark message consumed */
		conn->inStart = conn->inCursor;

		return msgLength;

nodata:
		/* Don't block if async read requested */
		if (async)
			return 0;
		/* Need to load more data */
		if (pqWait(TRUE, FALSE, conn) ||
			pqReadData(conn) < 0)
			return -2;
	}
}


/*
 * PQgetline - gets a newline-terminated string from the backend.
 *
 * See fe-exec.c for documentation.
 */
int
pqGetline2(PGconn *conn, char *s, int maxlen)
{
	int			result = 1;		/* return value if buffer overflows */

	if (conn->sock < 0)
	{
		*s = '\0';
		return EOF;
	}

	/*
	 * Since this is a purely synchronous routine, we don't bother to maintain
	 * conn->inCursor; there is no need to back up.
	 */
	while (maxlen > 1)
	{
		if (conn->inStart < conn->inEnd)
		{
			char		c = conn->inBuffer[conn->inStart++];

			if (c == '\n')
			{
				result = 0;		/* success exit */
				break;
			}
			*s++ = c;
			maxlen--;
		}
		else
		{
			/* need to load more data */
			if (pqWait(TRUE, FALSE, conn) ||
				pqReadData(conn) < 0)
			{
				result = EOF;
				break;
			}
		}
	}
	*s = '\0';

	return result;
}

/*
 * PQgetlineAsync - gets a COPY data row without blocking.
 *
 * See fe-exec.c for documentation.
 */
int
pqGetlineAsync2(PGconn *conn, char *buffer, int bufsize)
{
	int			avail;

	if (conn->asyncStatus != PGASYNC_COPY_OUT)
		return -1;				/* we are not doing a copy... */

	/*
	 * Move data from libpq's buffer to the caller's. We want to accept data
	 * only in units of whole lines, not partial lines.  This ensures that we
	 * can recognize the terminator line "\\.\n".  (Otherwise, if it happened
	 * to cross a packet/buffer boundary, we might hand the first one or two
	 * characters off to the caller, which we shouldn't.)
	 */

	conn->inCursor = conn->inStart;

	avail = bufsize;
	while (avail > 0 && conn->inCursor < conn->inEnd)
	{
		char		c = conn->inBuffer[conn->inCursor++];

		*buffer++ = c;
		--avail;
		if (c == '\n')
		{
			/* Got a complete line; mark the data removed from libpq */
			conn->inStart = conn->inCursor;
			/* Is it the endmarker line? */
			if (bufsize - avail == 3 && buffer[-3] == '\\' && buffer[-2] == '.')
				return -1;
			/* No, return the data line to the caller */
			return bufsize - avail;
		}
	}

	/*
	 * We don't have a complete line. We'd prefer to leave it in libpq's
	 * buffer until the rest arrives, but there is a special case: what if the
	 * line is longer than the buffer the caller is offering us?  In that case
	 * we'd better hand over a partial line, else we'd get into an infinite
	 * loop. Do this in a way that ensures we can't misrecognize a terminator
	 * line later: leave last 3 characters in libpq buffer.
	 */
	if (avail == 0 && bufsize > 3)
	{
		conn->inStart = conn->inCursor - 3;
		return bufsize - 3;
	}
	return 0;
}

/*
 * PQendcopy
 *
 * See fe-exec.c for documentation.
 */
int
pqEndcopy2(PGconn *conn)
{
	PGresult   *result;

	if (conn->asyncStatus != PGASYNC_COPY_IN &&
		conn->asyncStatus != PGASYNC_COPY_OUT)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("no COPY in progress\n"));
		return 1;
	}

	/*
	 * make sure no data is waiting to be sent, abort if we are non-blocking
	 * and the flush fails
	 */
	if (pqFlush(conn) && pqIsnonblocking(conn))
		return (1);

	/* non blocking connections may have to abort at this point. */
	if (pqIsnonblocking(conn) && PQisBusy(conn))
		return (1);

	/* Return to active duty */
	conn->asyncStatus = PGASYNC_BUSY;
	resetPQExpBuffer(&conn->errorMessage);

	/* Wait for the completion response */
	result = PQgetResult(conn);

	/* Expecting a successful result */
	if (result && result->resultStatus == PGRES_COMMAND_OK)
	{
		PQclear(result);
		return 0;
	}

	/*
	 * Trouble. For backwards-compatibility reasons, we issue the error
	 * message as if it were a notice (would be nice to get rid of this
	 * silliness, but too many apps probably don't handle errors from
	 * PQendcopy reasonably).  Note that the app can still obtain the error
	 * status from the PGconn object.
	 */
	if (conn->errorMessage.len > 0)
	{
		/* We have to strip the trailing newline ... pain in neck... */
		char		svLast = conn->errorMessage.data[conn->errorMessage.len - 1];

		if (svLast == '\n')
			conn->errorMessage.data[conn->errorMessage.len - 1] = '\0';
		pqInternalNotice(&conn->noticeHooks, "%s", conn->errorMessage.data);
		conn->errorMessage.data[conn->errorMessage.len - 1] = svLast;
	}

	PQclear(result);

	/*
	 * The worst case is that we've lost sync with the backend entirely due to
	 * application screwup of the copy in/out protocol. To recover, reset the
	 * connection (talk about using a sledgehammer...)
	 */
	pqInternalNotice(&conn->noticeHooks,
				   "lost synchronization with server, resetting connection");

	/*
	 * Users doing non-blocking connections need to handle the reset
	 * themselves, they'll need to check the connection status if we return an
	 * error.
	 */
	if (pqIsnonblocking(conn))
		PQresetStart(conn);
	else
		PQreset(conn);

	return 1;
}


/*
 * PQfn - Send a function call to the POSTGRES backend.
 *
 * See fe-exec.c for documentation.
 */
PGresult *
pqFunctionCall2(PGconn *conn, Oid fnid,
				int *result_buf, int *actual_result_len,
				int result_is_int,
				const PQArgBlock *args, int nargs)
{
	bool		needInput = false;
	ExecStatusType status = PGRES_FATAL_ERROR;
	char		id;
	int			i;

	/* PQfn already validated connection state */

	if (pqPutMsgStart('F', false, conn) < 0 ||	/* function call msg */
		pqPuts(" ", conn) < 0 ||	/* dummy string */
		pqPutInt(fnid, 4, conn) != 0 || /* function id */
		pqPutInt(nargs, 4, conn) != 0)	/* # of args */
	{
		pqHandleSendFailure(conn);
		return NULL;
	}

	for (i = 0; i < nargs; ++i)
	{							/* len.int4 + contents	   */
		if (pqPutInt(args[i].len, 4, conn))
		{
			pqHandleSendFailure(conn);
			return NULL;
		}

		if (args[i].isint)
		{
			if (pqPutInt(args[i].u.integer, 4, conn))
			{
				pqHandleSendFailure(conn);
				return NULL;
			}
		}
		else
		{
			if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
			{
				pqHandleSendFailure(conn);
				return NULL;
			}
		}
	}

	if (pqPutMsgEnd(conn) < 0 ||
		pqFlush(conn))
	{
		pqHandleSendFailure(conn);
		return NULL;
	}

	for (;;)
	{
		if (needInput)
		{
			/* Wait for some data to arrive (or for the channel to close) */
			if (pqWait(TRUE, FALSE, conn) ||
				pqReadData(conn) < 0)
				break;
		}

		/*
		 * Scan the message. If we run out of data, loop around to try again.
		 */
		conn->inCursor = conn->inStart;
		needInput = true;

		if (pqGetc(&id, conn))
			continue;

		/*
		 * We should see V or E response to the command, but might get N
		 * and/or A notices first. We also need to swallow the final Z before
		 * returning.
		 */
		switch (id)
		{
			case 'V':			/* function result */
				if (pqGetc(&id, conn))
					continue;
				if (id == 'G')
				{
					/* function returned nonempty value */
					if (pqGetInt(actual_result_len, 4, conn))
						continue;
					if (result_is_int)
					{
						if (pqGetInt(result_buf, 4, conn))
							continue;
					}
					else
					{
						if (pqGetnchar((char *) result_buf,
									   *actual_result_len,
									   conn))
							continue;
					}
					if (pqGetc(&id, conn))		/* get the last '0' */
						continue;
				}
				if (id == '0')
				{
					/* correctly finished function result message */
					status = PGRES_COMMAND_OK;
				}
				else
				{
					/* The backend violates the protocol. */
					printfPQExpBuffer(&conn->errorMessage,
								  libpq_gettext("protocol error: id=0x%x\n"),
									  id);
					pqSaveErrorResult(conn);
					conn->inStart = conn->inCursor;
					return pqPrepareAsyncResult(conn);
				}
				break;
			case 'E':			/* error return */
				if (pqGetErrorNotice2(conn, true))
					continue;
				status = PGRES_FATAL_ERROR;
				break;
			case 'A':			/* notify message */
				/* handle notify and go back to processing return values */
				if (getNotify(conn))
					continue;
				break;
			case 'N':			/* notice */
				/* handle notice and go back to processing return values */
				if (pqGetErrorNotice2(conn, false))
					continue;
				break;
			case 'Z':			/* backend is ready for new query */
				/* consume the message and exit */
				conn->inStart = conn->inCursor;
				/* if we saved a result object (probably an error), use it */
				if (conn->result)
					return pqPrepareAsyncResult(conn);
				return PQmakeEmptyPGresult(conn, status);
			default:
				/* The backend violates the protocol. */
				printfPQExpBuffer(&conn->errorMessage,
								  libpq_gettext("protocol error: id=0x%x\n"),
								  id);
				pqSaveErrorResult(conn);
				conn->inStart = conn->inCursor;
				return pqPrepareAsyncResult(conn);
		}
		/* Completed this message, keep going */
		conn->inStart = conn->inCursor;
		needInput = false;
	}

	/*
	 * We fall out of the loop only upon failing to read data.
	 * conn->errorMessage has been set by pqWait or pqReadData. We want to
	 * append it to any already-received error message.
	 */
	pqSaveErrorResult(conn);
	return pqPrepareAsyncResult(conn);
}


/*
 * Construct startup packet
 *
 * Returns a malloc'd packet buffer, or NULL if out of memory
 */
char *
pqBuildStartupPacket2(PGconn *conn, int *packetlen,
					  const PQEnvironmentOption *options)
{
	StartupPacket *startpacket;

	*packetlen = sizeof(StartupPacket);
	startpacket = (StartupPacket *) malloc(sizeof(StartupPacket));
	if (!startpacket)
		return NULL;

	MemSet(startpacket, 0, sizeof(StartupPacket));

	startpacket->protoVersion = htonl(conn->pversion);

	strncpy(startpacket->user, conn->pguser, SM_USER);
	strncpy(startpacket->database, conn->dbName, SM_DATABASE);
	strncpy(startpacket->tty, conn->pgtty, SM_TTY);

	if (conn->pgoptions)
		strncpy(startpacket->options, conn->pgoptions, SM_OPTIONS);

	return (char *) startpacket;
}