pqformat.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 */
void
pq_endmessage(StringInfo buf)
{
	/* msgtype was saved in cursor field */
	(void) pq_putmessage(buf->cursor, buf->data, buf->len);
	/* no need to complain about any failure, since pqcomm.c already did */
	pfree(buf->data);
	buf->data = NULL;
}


/* --------------------------------
 *		pq_begintypsend		- initialize for constructing a bytea result
 * --------------------------------
 */
void
pq_begintypsend(StringInfo buf)
{
	initStringInfo(buf);
	/* Reserve four bytes for the bytea length word */
	appendStringInfoCharMacro(buf, '\0');
	appendStringInfoCharMacro(buf, '\0');
	appendStringInfoCharMacro(buf, '\0');
	appendStringInfoCharMacro(buf, '\0');
}

/* --------------------------------
 *		pq_endtypsend	- finish constructing a bytea result
 *
 * The data buffer is returned as the palloc'd bytea value.  (We expect
 * that it will be suitably aligned for this because it has been palloc'd.)
 * We assume the StringInfoData is just a local variable in the caller and
 * need not be pfree'd.
 * --------------------------------
 */
bytea *
pq_endtypsend(StringInfo buf)
{
	bytea	   *result = (bytea *) buf->data;

	/* Insert correct length into bytea length word */
	Assert(buf->len >= VARHDRSZ);
	VARATT_SIZEP(result) = buf->len;

	return result;
}


/* --------------------------------
 *		pq_puttextmessage - generate a character set-converted message in one step
 *
 *		This is the same as the pqcomm.c routine pq_putmessage, except that
 *		the message body is a null-terminated string to which encoding
 *		conversion applies.
 * --------------------------------
 */
void
pq_puttextmessage(char msgtype, const char *str)
{
	int			slen = strlen(str);
	char	   *p;

	p = pg_server_to_client(str, slen);
	if (p != str)				/* actual conversion has been done? */
	{
		(void) pq_putmessage(msgtype, p, strlen(p) + 1);
		pfree(p);
		return;
	}
	(void) pq_putmessage(msgtype, str, slen + 1);
}


/* --------------------------------
 *		pq_putemptymessage - convenience routine for message with empty body
 * --------------------------------
 */
void
pq_putemptymessage(char msgtype)
{
	(void) pq_putmessage(msgtype, NULL, 0);
}


/* --------------------------------
 *		pq_getmsgbyte	- get a raw byte from a message buffer
 * --------------------------------
 */
int
pq_getmsgbyte(StringInfo msg)
{
	if (msg->cursor >= msg->len)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("no data left in message")));
	return (unsigned char) msg->data[msg->cursor++];
}

/* --------------------------------
 *		pq_getmsgint	- get a binary integer from a message buffer
 *
 *		Values are treated as unsigned.
 * --------------------------------
 */
unsigned int
pq_getmsgint(StringInfo msg, int b)
{
	unsigned int result;
	unsigned char n8;
	uint16		n16;
	uint32		n32;

	switch (b)
	{
		case 1:
			pq_copymsgbytes(msg, (char *) &n8, 1);
			result = n8;
			break;
		case 2:
			pq_copymsgbytes(msg, (char *) &n16, 2);
			result = ntohs(n16);
			break;
		case 4:
			pq_copymsgbytes(msg, (char *) &n32, 4);
			result = ntohl(n32);
			break;
		default:
			elog(ERROR, "unsupported integer size %d", b);
			result = 0;			/* keep compiler quiet */
			break;
	}
	return result;
}

/* --------------------------------
 *		pq_getmsgint64	- get a binary 8-byte int from a message buffer
 *
 * It is tempting to merge this with pq_getmsgint, but we'd have to make the
 * result int64 for all data widths --- that could be a big performance
 * hit on machines where int64 isn't efficient.
 * --------------------------------
 */
int64
pq_getmsgint64(StringInfo msg)
{
	int64		result;
	uint32		h32;
	uint32		l32;

	pq_copymsgbytes(msg, (char *) &h32, 4);
	pq_copymsgbytes(msg, (char *) &l32, 4);
	h32 = ntohl(h32);
	l32 = ntohl(l32);

#ifdef INT64_IS_BUSTED
	/* error out if incoming value is wider than 32 bits */
	result = l32;
	if ((result < 0) ? (h32 != -1) : (h32 != 0))
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("binary value is out of range for type bigint")));
#else
	result = h32;
	result <<= 32;
	result |= l32;
#endif

	return result;
}

/* --------------------------------
 *		pq_getmsgfloat4 - get a float4 from a message buffer
 *
 * See notes for pq_sendfloat4.
 * --------------------------------
 */
float4
pq_getmsgfloat4(StringInfo msg)
{
	union
	{
		float4		f;
		uint32		i;
	}			swap;

	swap.i = pq_getmsgint(msg, 4);
	return swap.f;
}

/* --------------------------------
 *		pq_getmsgfloat8 - get a float8 from a message buffer
 *
 * See notes for pq_sendfloat8.
 * --------------------------------
 */
float8
pq_getmsgfloat8(StringInfo msg)
{
#ifdef INT64_IS_BUSTED
	union
	{
		float8		f;
		uint32		h[2];
	}			swap;

	/* Have to figure out endianness by testing... */
	if (((uint32) 1) == htonl((uint32) 1))
	{
		/* machine seems to be big-endian, receive h[0] first */
		swap.h[0] = pq_getmsgint(msg, 4);
		swap.h[1] = pq_getmsgint(msg, 4);
	}
	else
	{
		/* machine seems to be little-endian, receive h[1] first */
		swap.h[1] = pq_getmsgint(msg, 4);
		swap.h[0] = pq_getmsgint(msg, 4);
	}
	return swap.f;
#else
	union
	{
		float8		f;
		int64		i;
	}			swap;

	swap.i = pq_getmsgint64(msg);
	return swap.f;
#endif
}

/* --------------------------------
 *		pq_getmsgbytes	- get raw data from a message buffer
 *
 *		Returns a pointer directly into the message buffer; note this
 *		may not have any particular alignment.
 * --------------------------------
 */
const char *
pq_getmsgbytes(StringInfo msg, int datalen)
{
	const char *result;

	if (datalen < 0 || datalen > (msg->len - msg->cursor))
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("insufficient data left in message")));
	result = &msg->data[msg->cursor];
	msg->cursor += datalen;
	return result;
}

/* --------------------------------
 *		pq_copymsgbytes - copy raw data from a message buffer
 *
 *		Same as above, except data is copied to caller's buffer.
 * --------------------------------
 */
void
pq_copymsgbytes(StringInfo msg, char *buf, int datalen)
{
	if (datalen < 0 || datalen > (msg->len - msg->cursor))
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("insufficient data left in message")));
	memcpy(buf, &msg->data[msg->cursor], datalen);
	msg->cursor += datalen;
}

/* --------------------------------
 *		pq_getmsgtext	- get a counted text string (with conversion)
 *
 *		Always returns a pointer to a freshly palloc'd result.
 *		The result has a trailing null, *and* we return its strlen in *nbytes.
 * --------------------------------
 */
char *
pq_getmsgtext(StringInfo msg, int rawbytes, int *nbytes)
{
	char	   *str;
	char	   *p;

	if (rawbytes < 0 || rawbytes > (msg->len - msg->cursor))
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("insufficient data left in message")));
	str = &msg->data[msg->cursor];
	msg->cursor += rawbytes;

	p = pg_client_to_server(str, rawbytes);
	if (p != str)				/* actual conversion has been done? */
		*nbytes = strlen(p);
	else
	{
		p = (char *) palloc(rawbytes + 1);
		memcpy(p, str, rawbytes);
		p[rawbytes] = '\0';
		*nbytes = rawbytes;
	}
	return p;
}

/* --------------------------------
 *		pq_getmsgstring - get a null-terminated text string (with conversion)
 *
 *		May return a pointer directly into the message buffer, or a pointer
 *		to a palloc'd conversion result.
 * --------------------------------
 */
const char *
pq_getmsgstring(StringInfo msg)
{
	char	   *str;
	int			slen;

	str = &msg->data[msg->cursor];

	/*
	 * It's safe to use strlen() here because a StringInfo is guaranteed to
	 * have a trailing null byte.  But check we found a null inside the
	 * message.
	 */
	slen = strlen(str);
	if (msg->cursor + slen >= msg->len)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("invalid string in message")));
	msg->cursor += slen + 1;

	return pg_client_to_server(str, slen);
}

/* --------------------------------
 *		pq_getmsgend	- verify message fully consumed
 * --------------------------------
 */
void
pq_getmsgend(StringInfo msg)
{
	if (msg->cursor != msg->len)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("invalid message format")));
}