fe-protocol2.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * fe-protocol2.c
 *	  functions that are specific to frontend/backend protocol version 2
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol2.c,v 1.19.2.1 2005/11/22 18:23:30 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include <errno.h>
#include <ctype.h>
#include <fcntl.h>

#include "libpq-fe.h"
#include "libpq-int.h"

#include "mb/pg_wchar.h"

#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#include <netinet/in.h>
#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif
#include <arpa/inet.h>
#endif


static int	getRowDescriptions(PGconn *conn);
static int	getAnotherTuple(PGconn *conn, bool binary);
static int	pqGetErrorNotice2(PGconn *conn, bool isError);
static void checkXactStatus(PGconn *conn, const char *cmdTag);
static int	getNotify(PGconn *conn);


/*
 *		pqSetenvPoll
 *
 * Polls the process of passing the values of a standard set of environment
 * variables to the backend.
 */
PostgresPollingStatusType
pqSetenvPoll(PGconn *conn)
{
	PGresult   *res;

	if (conn == NULL || conn->status == CONNECTION_BAD)
		return PGRES_POLLING_FAILED;

	/* Check whether there are any data for us */
	switch (conn->setenv_state)
	{
			/* These are reading states */
		case SETENV_STATE_OPTION_WAIT:
		case SETENV_STATE_QUERY1_WAIT:
		case SETENV_STATE_QUERY2_WAIT:
			{
				/* Load waiting data */
				int			n = pqReadData(conn);

				if (n < 0)
					goto error_return;
				if (n == 0)
					return PGRES_POLLING_READING;

				break;
			}

			/* These are writing states, so we just proceed. */
		case SETENV_STATE_OPTION_SEND:
		case SETENV_STATE_QUERY1_SEND:
		case SETENV_STATE_QUERY2_SEND:
			break;

			/* Should we raise an error if called when not active? */
		case SETENV_STATE_IDLE:
			return PGRES_POLLING_OK;

		default:
			printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext(
											"invalid setenv state %c, "
								 "probably indicative of memory corruption\n"
											),
							  conn->setenv_state);
			goto error_return;
	}

	/* We will loop here until there is nothing left to do in this call. */
	for (;;)
	{
		switch (conn->setenv_state)
		{
			case SETENV_STATE_OPTION_SEND:
				{
					/*
					 * Send SET commands for stuff directed by Environment
					 * Options.  Note: we assume that SET commands won't start
					 * transaction blocks, even in a 7.3 server with
					 * autocommit off.
					 */
					char		setQuery[100];	/* note length limit in
												 * sprintf below */

					if (conn->next_eo->envName)
					{
						const char *val;

						if ((val = getenv(conn->next_eo->envName)))
						{
							if (pg_strcasecmp(val, "default") == 0)
								sprintf(setQuery, "SET %s = DEFAULT",
										conn->next_eo->pgName);
							else
								sprintf(setQuery, "SET %s = '%.60s'",
										conn->next_eo->pgName, val);
#ifdef CONNECTDEBUG
							fprintf(stderr,
								  "Use environment variable %s to send %s\n",
									conn->next_eo->envName, setQuery);
#endif
							if (!PQsendQuery(conn, setQuery))
								goto error_return;

							conn->setenv_state = SETENV_STATE_OPTION_WAIT;
						}
						else
							conn->next_eo++;
					}
					else
					{
						/* No more options to send, so move on to querying */
						conn->setenv_state = SETENV_STATE_QUERY1_SEND;
					}
					break;
				}

			case SETENV_STATE_OPTION_WAIT:
				{
					if (PQisBusy(conn))
						return PGRES_POLLING_READING;

					res = PQgetResult(conn);

					if (res)
					{
						if (PQresultStatus(res) != PGRES_COMMAND_OK)
						{
							PQclear(res);
							goto error_return;
						}
						PQclear(res);
						/* Keep reading until PQgetResult returns NULL */
					}
					else
					{
						/* Query finished, so send the next option */
						conn->next_eo++;
						conn->setenv_state = SETENV_STATE_OPTION_SEND;
					}
					break;
				}

			case SETENV_STATE_QUERY1_SEND:
				{
					/*
					 * Issue query to get information we need.	Here we must
					 * use begin/commit in case autocommit is off by default
					 * in a 7.3 server.
					 *
					 * Note: version() exists in all protocol-2.0-supporting
					 * backends.  In 7.3 it would be safer to write
					 * pg_catalog.version(), but we can't do that without
					 * causing problems on older versions.
					 */
					if (!PQsendQuery(conn, "begin; select version(); end"))
						goto error_return;

					conn->setenv_state = SETENV_STATE_QUERY1_WAIT;
					return PGRES_POLLING_READING;
				}

			case SETENV_STATE_QUERY1_WAIT:
				{
					if (PQisBusy(conn))
						return PGRES_POLLING_READING;

					res = PQgetResult(conn);

					if (res)
					{
						char	   *val;

						if (PQresultStatus(res) == PGRES_COMMAND_OK)
						{
							/* ignore begin/commit command results */
							PQclear(res);
							continue;
						}

						if (PQresultStatus(res) != PGRES_TUPLES_OK ||
							PQntuples(res) != 1)
						{
							PQclear(res);
							goto error_return;
						}

						/*
						 * Extract server version and save as if
						 * ParameterStatus
						 */
						val = PQgetvalue(res, 0, 0);
						if (val && strncmp(val, "PostgreSQL ", 11) == 0)
						{
							char	   *ptr;

							/* strip off PostgreSQL part */
							val += 11;

							/*
							 * strip off platform part (scribbles on result,
							 * naughty naughty)
							 */
							ptr = strchr(val, ' ');
							if (ptr)
								*ptr = '\0';

							pqSaveParameterStatus(conn, "server_version",
												  val);
						}

						PQclear(res);
						/* Keep reading until PQgetResult returns NULL */
					}
					else
					{
						/* Query finished, move to next */
						conn->setenv_state = SETENV_STATE_QUERY2_SEND;
					}
					break;
				}

			case SETENV_STATE_QUERY2_SEND:
				{
					const char *query;

					/*
					 * pg_client_encoding does not exist in pre-7.2 servers.
					 * So we need to be prepared for an error here.  Do *not*
					 * start a transaction block, except in 7.3 servers where
					 * we need to prevent autocommit-off from starting a
					 * transaction anyway.
					 */
					if (conn->sversion >= 70300 &&
						conn->sversion < 70400)
						query = "begin; select pg_catalog.pg_client_encoding(); end";
					else
						query = "select pg_client_encoding()";
					if (!PQsendQuery(conn, query))
						goto error_return;

					conn->setenv_state = SETENV_STATE_QUERY2_WAIT;
					return PGRES_POLLING_READING;
				}

			case SETENV_STATE_QUERY2_WAIT:
				{
					if (PQisBusy(conn))
						return PGRES_POLLING_READING;

					res = PQgetResult(conn);

					if (res)
					{
						const char *val;

						if (PQresultStatus(res) == PGRES_COMMAND_OK)
						{
							/* ignore begin/commit command results */
							PQclear(res);
							continue;
						}

						if (PQresultStatus(res) == PGRES_TUPLES_OK &&
							PQntuples(res) == 1)
						{
							/* Extract client encoding and save it */
							val = PQgetvalue(res, 0, 0);
							if (val && *val)	/* null should not happen, but */
								pqSaveParameterStatus(conn, "client_encoding",
													  val);
						}
						else
						{
							/*
							 * Error: presumably function not available, so
							 * use PGCLIENTENCODING or SQL_ASCII as the
							 * fallback.
							 */
							val = getenv("PGCLIENTENCODING");
							if (val && *val)
								pqSaveParameterStatus(conn, "client_encoding",
													  val);
							else
								pqSaveParameterStatus(conn, "client_encoding",
													  "SQL_ASCII");
						}

						PQclear(res);
						/* Keep reading until PQgetResult returns NULL */
					}
					else
					{
						/* Query finished, so we're done */
						conn->setenv_state = SETENV_STATE_IDLE;
						return PGRES_POLLING_OK;
					}
					break;
				}

			default:
				printfPQExpBuffer(&conn->errorMessage,
								  libpq_gettext("invalid state %c, "
							   "probably indicative of memory corruption\n"),
								  conn->setenv_state);
				goto error_return;
		}
	}

	/* Unreachable */

error_return:
	conn->setenv_state = SETENV_STATE_IDLE;
	return PGRES_POLLING_FAILED;
}


/*
 * parseInput: if appropriate, parse input data from backend
 * until input is exhausted or a stopping state is reached.
 * Note that this function will NOT attempt to read more data from the backend.
 */
void
pqParseInput2(PGconn *conn)
{
	char		id;

	/*
	 * Loop to parse successive complete messages available in the buffer.
	 */
	for (;;)
	{
		/*
		 * Quit if in COPY_OUT state: we expect raw data from the server until
		 * PQendcopy is called.  Don't try to parse it according to the normal
		 * protocol.  (This is bogus.  The data lines ought to be part of the
		 * protocol and have identifying leading characters.)
		 */
		if (conn->asyncStatus == PGASYNC_COPY_OUT)
			return;

		/*
		 * OK to try to read a message type code.
		 */
		conn->inCursor = conn->inStart;
		if (pqGetc(&id, conn))
			return;

		/*
		 * NOTIFY and NOTICE messages can happen in any state besides COPY
		 * OUT; always process them right away.
		 *
		 * Most other messages should only be processed while in BUSY state.
		 * (In particular, in READY state we hold off further parsing until
		 * the application collects the current PGresult.)
		 *
		 * However, if the state is IDLE then we got trouble; we need to deal
		 * with the unexpected message somehow.
		 */
		if (id == 'A')
		{
			if (getNotify(conn))
				return;
		}
		else if (id == 'N')
		{
			if (pqGetErrorNotice2(conn, false))
				return;
		}
		else if (conn->asyncStatus != PGASYNC_BUSY)
		{
			/* If not IDLE state, just wait ... */
			if (conn->asyncStatus != PGASYNC_IDLE)
				return;

			/*
			 * Unexpected message in IDLE state; need to recover somehow.
			 * ERROR messages are displayed using the notice processor;
			 * anything else is just dropped on the floor after displaying a
			 * suitable warning notice.  (An ERROR is very possibly the
			 * backend telling us why it is about to close the connection, so
			 * we don't want to just discard it...)
			 */
			if (id == 'E')
			{
				if (pqGetErrorNotice2(conn, false /* treat as notice */ ))
					return;
			}
			else
			{
				pqInternalNotice(&conn->noticeHooks,
						"message type 0x%02x arrived from server while idle",
								 id);
				/* Discard the unexpected message; good idea?? */
				conn->inStart = conn->inEnd;
				break;
			}
		}
		else
		{
			/*
			 * In BUSY state, we can process everything.
			 */
			switch (id)
			{
				case 'C':		/* command complete */
					if (pqGets(&conn->workBuffer, conn))
						return;
					if (conn->result == NULL)
					{
						conn->result = PQmakeEmptyPGresult(conn,
														   PGRES_COMMAND_OK);
						if (!conn->result)
							return;
					}
					strncpy(conn->result->cmdStatus, conn->workBuffer.data,
							CMDSTATUS_LEN);
					checkXactStatus(conn, conn->workBuffer.data);
					conn->asyncStatus = PGASYNC_READY;
					break;
				case 'E':		/* error return */
					if (pqGetErrorNotice2(conn, true))
						return;
					conn->asyncStatus = PGASYNC_READY;
					break;
				case 'Z':		/* backend is ready for new query */
					conn->asyncStatus = PGASYNC_IDLE;
					break;
				case 'I':		/* empty query */
					/* read and throw away the closing '\0' */
					if (pqGetc(&id, conn))
						return;
					if (id != '\0')
						pqInternalNotice(&conn->noticeHooks,
										 "unexpected character %c following empty query response (\"I\" message)",
										 id);
					if (conn->result == NULL)
						conn->result = PQmakeEmptyPGresult(conn,
														   PGRES_EMPTY_QUERY);
					conn->asyncStatus = PGASYNC_READY;
					break;
				case 'K':		/* secret key data from the backend */

					/*
					 * This is expected only during backend startup, but it's
					 * just as easy to handle it as part of the main loop.
					 * Save the data and continue processing.
					 */
					if (pqGetInt(&(conn->be_pid), 4, conn))
						return;
					if (pqGetInt(&(conn->be_key), 4, conn))
						return;
					break;