fe-exec.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		{
			/* 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;
	else
		return NULL;
}

/*
 * PQfnumber: find column number given column name
 *
 * The column name is parsed as if it were in a SQL statement, including
 * case-folding and double-quote processing.  But note a possible gotcha:
 * downcasing in the frontend might follow different locale rules than
 * downcasing in the backend...
 *
 * Returns -1 if no match.	In the present backend it is also possible
 * to have multiple matches, in which case the first one is found.
 */
int
PQfnumber(const PGresult *res, const char *field_name)
{
	char	   *field_case;
	bool		in_quotes;
	char	   *iptr;
	char	   *optr;
	int			i;

	if (!res)
		return -1;

	/*
	 * Note: it is correct to reject a zero-length input string; the proper
	 * input to match a zero-length field name would be "".
	 */
	if (field_name == NULL ||
		field_name[0] == '\0' ||
		res->attDescs == NULL)
		return -1;

	/*
	 * Note: this code will not reject partially quoted strings, eg
	 * foo"BAR"foo will become fooBARfoo when it probably ought to be an error
	 * condition.
	 */
	field_case = strdup(field_name);
	if (field_case == NULL)
		return -1;				/* grotty */

	in_quotes = false;
	optr = field_case;
	for (iptr = field_case; *iptr; iptr++)
	{
		char		c = *iptr;

		if (in_quotes)
		{
			if (c == '"')
			{
				if (iptr[1] == '"')
				{
					/* doubled quotes become a single quote */
					*optr++ = '"';
					iptr++;
				}
				else
					in_quotes = false;
			}
			else
				*optr++ = c;
		}
		else if (c == '"')
			in_quotes = true;
		else
		{
			c = pg_tolower((unsigned char) c);
			*optr++ = c;
		}
	}
	*optr = '\0';

	for (i = 0; i < res->numAttributes; i++)
	{
		if (strcmp(field_case, res->attDescs[i].name) == 0)
		{
			free(field_case);
			return i;
		}
	}
	free(field_case);
	return -1;
}

Oid
PQftable(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return InvalidOid;
	if (res->attDescs)
		return res->attDescs[field_num].tableid;
	else
		return InvalidOid;
}

int
PQftablecol(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return 0;
	if (res->attDescs)
		return res->attDescs[field_num].columnid;
	else
		return 0;
}

int
PQfformat(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return 0;
	if (res->attDescs)
		return res->attDescs[field_num].format;
	else
		return 0;
}

Oid
PQftype(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return InvalidOid;
	if (res->attDescs)
		return res->attDescs[field_num].typid;
	else
		return InvalidOid;
}

int
PQfsize(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return 0;
	if (res->attDescs)
		return res->attDescs[field_num].typlen;
	else
		return 0;
}

int
PQfmod(const PGresult *res, int field_num)
{
	if (!check_field_number(res, field_num))
		return 0;
	if (res->attDescs)
		return res->attDescs[field_num].atttypmod;
	else
		return 0;
}

char *
PQcmdStatus(PGresult *res)
{
	if (!res)
		return NULL;
	return res->cmdStatus;
}

/*
 * PQoidStatus -
 *	if the last command was an INSERT, return the oid string
 *	if not, return ""
 */
char *