fe-exec.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,443 行 · 第 1/4 页

				/* keep waiting to swallow the copy's failure message */
			}
			else
			{
				/* In older protocols we have to punt */
				printfPQExpBuffer(&conn->errorMessage,
								  libpq_gettext("COPY IN state must be terminated first\n"));
				return false;
			}
		}
		else if (resultStatus == PGRES_COPY_OUT)
		{
			if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
			{
				/*
				 * In protocol 3, we can get out of a COPY OUT state: we
				 * just switch back to BUSY and allow the remaining COPY
				 * data to be dropped on the floor.
				 */
				conn->asyncStatus = PGASYNC_BUSY;
				/* keep waiting to swallow the copy's completion message */
			}
			else
			{
				/* In older protocols we have to punt */
				printfPQExpBuffer(&conn->errorMessage,
								  libpq_gettext("COPY OUT state must be terminated first\n"));
				return false;
			}
		}
		/* check for loss of connection, too */
		if (conn->status == CONNECTION_BAD)
			return false;
	}

	/* OK to send a command */
	return true;
}

/*
 * Common code for PQexec and sibling routines: wait for command result
 */
static PGresult *
PQexecFinish(PGconn *conn)
{
	PGresult   *result;
	PGresult   *lastResult;

	/*
	 * For backwards compatibility, return the last result if there are
	 * more than one --- but merge error messages if we get more than one
	 * error result.
	 *
	 * We have to stop if we see copy in/out, however. We will resume parsing
	 * after application performs the data transfer.
	 *
	 * Also stop if the connection is lost (else we'll loop infinitely).
	 */
	lastResult = NULL;
	while ((result = PQgetResult(conn)) != NULL)
	{
		if (lastResult)
		{
			if (lastResult->resultStatus == PGRES_FATAL_ERROR &&
				result->resultStatus == PGRES_FATAL_ERROR)
			{
				pqCatenateResultError(lastResult, result->errMsg);
				PQclear(result);
				result = lastResult;

				/*
				 * Make sure PQerrorMessage agrees with concatenated
				 * result
				 */
				resetPQExpBuffer(&conn->errorMessage);
				appendPQExpBufferStr(&conn->errorMessage, result->errMsg);
			}
			else
				PQclear(lastResult);
		}
		lastResult = result;
		if (result->resultStatus == PGRES_COPY_IN ||
			result->resultStatus == PGRES_COPY_OUT ||
			conn->status == CONNECTION_BAD)
			break;
	}

	return lastResult;
}

/*
 * PQnotifies
 *	  returns a PGnotify* structure of the latest async notification
 * that has not yet been handled
 *
 * returns NULL, if there is currently
 * no unhandled async notification from the backend
 *
 * the CALLER is responsible for FREE'ing the structure returned
 */
PGnotify *
PQnotifies(PGconn *conn)
{
	Dlelem	   *e;
	PGnotify   *event;

	if (!conn)
		return NULL;

	/* Parse any available data to see if we can extract NOTIFY messages. */
	parseInput(conn);

	/* RemHead returns NULL if list is empty */
	e = DLRemHead(conn->notifyList);
	if (!e)
		return NULL;
	event = (PGnotify *) DLE_VAL(e);
	DLFreeElem(e);
	return event;
}

/*
 * PQputCopyData - send some data to the backend during COPY IN
 *
 * Returns 1 if successful, 0 if data could not be sent (only possible
 * in nonblock mode), or -1 if an error occurs.
 */
int
PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
{
	if (!conn)
		return -1;
	if (conn->asyncStatus != PGASYNC_COPY_IN)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("no COPY in progress\n"));
		return -1;
	}

	/*
	 * Check for NOTICE messages coming back from the server.  Since the
	 * server might generate multiple notices during the COPY, we have to
	 * consume those in a reasonably prompt fashion to prevent the comm
	 * buffers from filling up and possibly blocking the server.
	 */
	if (!PQconsumeInput(conn))
		return -1;				/* I/O failure */
	parseInput(conn);

	if (nbytes > 0)
	{
		/*
		 * Try to flush any previously sent data in preference to growing
		 * the output buffer.  If we can't enlarge the buffer enough to
		 * hold the data, return 0 in the nonblock case, else hard error.
		 * (For simplicity, always assume 5 bytes of overhead even in
		 * protocol 2.0 case.)
		 */
		if ((conn->outBufSize - conn->outCount - 5) < nbytes)
		{
			if (pqFlush(conn) < 0)
				return -1;
			if (pqCheckOutBufferSpace(conn->outCount + 5 + nbytes, conn))
				return pqIsnonblocking(conn) ? 0 : -1;
		}
		/* Send the data (too simple to delegate to fe-protocol files) */
		if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		{
			if (pqPutMsgStart('d', false, conn) < 0 ||
				pqPutnchar(buffer, nbytes, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
		else
		{
			if (pqPutMsgStart(0, false, conn) < 0 ||
				pqPutnchar(buffer, nbytes, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
	}
	return 1;
}

/*
 * PQputCopyEnd - send EOF indication to the backend during COPY IN
 *
 * After calling this, use PQgetResult() to check command completion status.
 *
 * Returns 1 if successful, 0 if data could not be sent (only possible
 * in nonblock mode), or -1 if an error occurs.
 */
int
PQputCopyEnd(PGconn *conn, const char *errormsg)
{
	if (!conn)
		return -1;
	if (conn->asyncStatus != PGASYNC_COPY_IN)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("no COPY in progress\n"));
		return -1;
	}

	/*
	 * Send the COPY END indicator.  This is simple enough that we don't
	 * bother delegating it to the fe-protocol files.
	 */
	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
	{
		if (errormsg)
		{
			/* Send COPY FAIL */
			if (pqPutMsgStart('f', false, conn) < 0 ||
				pqPuts(errormsg, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
		else
		{
			/* Send COPY DONE */
			if (pqPutMsgStart('c', false, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
		/*
		 * If we sent the COPY command in extended-query mode, we must
		 * issue a Sync as well.
		 */
		if (conn->ext_query)
		{
			if (pqPutMsgStart('S', false, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
	}
	else
	{
		if (errormsg)
		{
			/* Ooops, no way to do this in 2.0 */
			printfPQExpBuffer(&conn->errorMessage,
			 libpq_gettext("function requires at least protocol version 3.0\n"));
			return -1;
		}
		else
		{
			/* Send old-style end-of-data marker */
			if (pqPutMsgStart(0, false, conn) < 0 ||
				pqPutnchar("\\.\n", 3, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return -1;
		}
	}

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

	/* Try to flush data */
	if (pqFlush(conn) < 0)
		return -1;

	return 1;
}

/*
 * 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
PQgetCopyData(PGconn *conn, char **buffer, int async)
{
	*buffer = NULL;				/* for all failure cases */
	if (!conn)
		return -2;
	if (conn->asyncStatus != PGASYNC_COPY_OUT)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("no COPY in progress\n"));
		return -2;
	}
	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		return pqGetCopyData3(conn, buffer, async);
	else
		return pqGetCopyData2(conn, buffer, async);
}

/*
 * PQgetline - gets a newline-terminated string from the backend.
 *
 * Chiefly here so that applications can use "COPY <rel> to stdout"
 * and read the output string.	Returns a null-terminated string in s.
 *
 * XXX this routine is now deprecated, because it can't handle binary data.
 * If called during a COPY BINARY we return EOF.
 *
 * PQgetline reads up to maxlen-1 characters (like fgets(3)) but strips
 * the terminating \n (like gets(3)).
 *
 * CAUTION: the caller is responsible for detecting the end-of-copy signal
 * (a line containing just "\.") when using this routine.
 *
 * RETURNS:
 *		EOF if error (eg, invalid arguments are given)
 *		0 if EOL is reached (i.e., \n has been read)
 *				(this is required for backward-compatibility -- this
 *				 routine used to always return EOF or 0, assuming that
 *				 the line ended within maxlen bytes.)
 *		1 in other cases (i.e., the buffer was filled before \n is reached)
 */
int
PQgetline(PGconn *conn, char *s, int maxlen)
{
	if (!s || maxlen <= 0)
		return EOF;
	*s = '\0';
	/* maxlen must be at least 3 to hold the \. terminator! */
	if (maxlen < 3)
		return EOF;

	if (!conn)
		return EOF;

	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		return pqGetline3(conn, s, maxlen);
	else
		return pqGetline2(conn, s, maxlen);
}

/*
 * PQgetlineAsync - gets a COPY data row without blocking.
 *
 * This routine is for applications that want to do "COPY <rel> to stdout"
 * asynchronously, that is without blocking.  Having issued the COPY command
 * and gotten a PGRES_COPY_OUT response, the app should call PQconsumeInput
 * and this routine until the end-of-data signal is detected.  Unlike
 * PQgetline, this routine takes responsibility for detecting end-of-data.
 *
 * On each call, PQgetlineAsync will return data if a complete data row
 * is available in libpq's input buffer.  Otherwise, no data is returned
 * until the rest of the row arrives.
 *
 * If -1 is returned, the end-of-data signal has been recognized (and removed
 * from libpq's input buffer).  The caller *must* next call PQendcopy and
 * then return to normal processing.
 *
 * RETURNS:
 *	 -1    if the end-of-copy-data marker has been recognized
 *	 0	   if no data is available
 *	 >0    the number of bytes returned.
 *
 * The data returned will not extend beyond a data-row boundary.  If possible
 * a whole row will be returned at one time.  But if the buffer offered by
 * the caller is too small to hold a row sent by the backend, then a partial
 * data row will be returned.  In text mode this can be detected by testing
 * whether the last returned byte is '\n' or not.
 *
 * The returned data is *not* null-terminated.
 */

int
PQgetlineAsync(PGconn *conn, char *buffer, int bufsize)
{
	if (!conn)
		return -1;

	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		return pqGetlineAsync3(conn, buffer, bufsize);
	else
		return pqGetlineAsync2(conn, buffer, bufsize);
}

/*
 * PQputline -- sends a string to the backend during COPY IN.
 * Returns 0 if OK, EOF if not.
 *
 * This is deprecated primarily because the return convention doesn't allow
 * caller to tell the difference between a hard error and a nonblock-mode
 * send failure.
 */
int
PQputline(PGconn *conn, const char *s)
{
	return PQputnbytes(conn, s, strlen(s));
}

/*
 * PQputnbytes -- like PQputline, but buffer need not be null-terminated.
 * Returns 0 if OK, EOF if not.
 */
int
PQputnbytes(PGconn *conn, const char *buffer, int nbytes)
{
	if (PQputCopyData(conn, buffer, nbytes) > 0)
		return 0;
	else
		return EOF;
}

/*
 * PQendcopy
 *		After completing the data transfer portion of a copy in/out,
 *		the application must call this routine to finish the command protocol.
 *
 * When using protocol 3.0 this is deprecated; it's cleaner to use PQgetResult
 * to get the transfer status.	Note however that when using 2.0 protocol,
 * recovering from a copy failure often requires a PQreset.  PQendcopy will
 * take care of that, PQgetResult won't.
 *
 * RETURNS:
 *		0 on success
 *		1 on failure
 */
int
PQendcopy(PGconn *conn)
{
	if (!conn)
		return 0;

	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		return pqEndcopy3(conn);
	else
		return pqEndcopy2(conn);
}


/* ----------------
 *		PQfn -	Send a function call to the POSTGRES backend.
 *
 *		conn			: backend connection
 *		fnid			: function id
 *		result_buf		: pointer to result buffer (&int if integer)
 *		result_len		: length of return value.
 *		actual_result_len: actual length returned. (differs from result_len
 *						  for varlena structures.)
 *		result_type		: If the result is an integer, this must be 1,
 *						  otherwise this should be 0
 *		args			: pointer to an array of function arguments.
 *						  (each has length, if integer, and value/pointer)
 *		nargs			: # of arguments in args array.
 *
 * RETURNS
 *		PGresult with status = PGRES_COMMAND_OK if successful.
 *			*actual_result_len is > 0 if there is a return value, 0 if not.
 *		PGresult with status = PGRES_FATAL_ERROR if backend returns an error.
 *		NULL on communications failure.  conn->errorMessage will be set.
 * ----------------
 */

PGresult *
PQfn(PGconn *conn,
	 int fnid,
	 int *result_buf,
	 int *actual_result_len,
	 int result_is_int,
	 const PQArgBlock *args,
	 int nargs)
{
	*actual_result_len = 0;

	if (!conn)
		return NULL;

	/* clear the error string */
	resetPQExpBuffer(&conn->errorMessage);

	if (conn->sock < 0 || conn->asyncStatus != PGASYNC_IDLE ||
		conn->result != NULL)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("connection in wrong state\n"));
		return NULL;
	}

	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		return pqFunctionCall3(conn, fnid,
							   result_buf, actual_result_len,
							   result_is_int,
							   args, nargs);
	else
		return pqFunctionCall2(conn, fnid,
							   result_buf, actual_result_len,
							   result_is_int,
							   args, nargs);
}


/* ====== accessor funcs for PGresult ======== */

ExecStatusType
PQresultStatus(const PGresult *res)
{
	if (!res)
		return PGRES_FATAL_ERROR;
	return res->resultStatus;
}

char *
PQresStatus(ExecStatusType status)
{
	if (status < 0 || status >= sizeof pgresStatus / sizeof pgresStatus[0])
		return libpq_gettext("invalid ExecStatusType code");
	return pgresStatus[status];
}

char *
PQresultErrorMessage(const PGresult *res)
{
	if (!res || !res->errMsg)
		return "";
	return res->errMsg;
}

char *
PQresultErrorField(const PGresult *res, int fieldcode)
{
	PGMessageField *pfield;

	if (!res)
		return NULL;
	for (pfield = res->errFields; pfield != NULL; pfield = pfield->next)
	{
		if (pfield->code == fieldcode)
			return pfield->contents;
	}
	return NULL;
}

int
PQntuples(const PGresult *res)
{
	if (!res)
		return 0;
	return res->ntups;
}

int
PQnfields(const PGresult *res)
{
	if (!res)
		return 0;
	return res->numAttributes;
}

int
PQbinaryTuples(const PGresult *res)
{
	if (!res)
		return 0;
	return res->binary;
}

/*
 * Helper routines to range-check field numbers and tuple numbers.
 * Return TRUE if OK, FALSE if not
 */

static int
check_field_number(const PGresult *res, int field_num)
{
	if (!res)
		return FALSE;			/* no way to display error message... */
	if (field_num < 0 || field_num >= res->numAttributes)
	{
		pqInternalNotice(&res->noticeHooks,
						 "column number %d is out of range 0..%d",
						 field_num, res->numAttributes - 1);
		return FALSE;
	}
	return TRUE;
}

static int
check_tuple_field_number(const PGresult *res,
						 int tup_num, int field_num)
{
	if (!res)
		return FALSE;			/* no way to display error message... */
	if (tup_num < 0 || tup_num >= res->ntups)
	{
		pqInternalNotice(&res->noticeHooks,
						 "row number %d is out of range 0..%d",
						 tup_num, res->ntups - 1);
		return FALSE;
	}
	if (field_num < 0 || field_num >= res->numAttributes)
	{
		pqInternalNotice(&res->noticeHooks,
						 "column number %d is out of range 0..%d",
						 field_num, res->numAttributes - 1);
		return FALSE;
	}
	return TRUE;
}

/*
 * returns NULL if the field_num is invalid
 */
char *
PQfname(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return NULL;
	if (res->attDescs)
		return res->attDescs[field_num].name;