pqcomm.c

关系型数据库 Postgresql 6.5.2

							 (struct sockaddr *) & port->raddr,
							 &addrlen)) < 0)
	{
		perror("postmaster: StreamConnection: accept");
		return STATUS_ERROR;
	}

	/* fill in the server (local) address */
	addrlen = sizeof(port->laddr);
	if (getsockname(port->sock, (struct sockaddr *) & port->laddr,
					&addrlen) < 0)
	{
		perror("postmaster: StreamConnection: getsockname");
		return STATUS_ERROR;
	}

	/* select TCP_NODELAY option if it's a TCP connection */
	if (port->laddr.sa.sa_family == AF_INET)
	{
		struct protoent *pe;
		int			on = 1;

		pe = getprotobyname("TCP");
		if (pe == NULL)
		{
			perror("postmaster: StreamConnection: getprotobyname");
			return STATUS_ERROR;
		}
		if (setsockopt(port->sock, pe->p_proto, TCP_NODELAY,
					   &on, sizeof(on)) < 0)
		{
			perror("postmaster: StreamConnection: setsockopt");
			return STATUS_ERROR;
		}
	}

	/* reset to non-blocking */
	fcntl(port->sock, F_SETFL, 1);

	return STATUS_OK;
}

/*
 * StreamClose -- close a client/backend connection
 */
void
StreamClose(int sock)
{
	close(sock);
}


/* --------------------------------
 * Low-level I/O routines begin here.
 *
 * These routines communicate with a frontend client across a connection
 * already established by the preceding routines.
 * --------------------------------
 */


/* --------------------------------
 *		pq_recvbuf - load some bytes into the input buffer
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
static int
pq_recvbuf(void)
{
	if (PqRecvPointer > 0)
	{
		if (PqRecvLength > PqRecvPointer)
		{
			/* still some unread data, left-justify it in the buffer */
			memmove(PqRecvBuffer, PqRecvBuffer + PqRecvPointer,
					PqRecvLength - PqRecvPointer);
			PqRecvLength -= PqRecvPointer;
			PqRecvPointer = 0;
		}
		else
			PqRecvLength = PqRecvPointer = 0;
	}

	/* Can fill buffer from PqRecvLength and upwards */
	for (;;)
	{
		int			r = recv(MyProcPort->sock, PqRecvBuffer + PqRecvLength,
							 PQ_BUFFER_SIZE - PqRecvLength, 0);

		if (r < 0)
		{
			if (errno == EINTR)
				continue;		/* Ok if interrupted */

			/*
			 * We would like to use elog() here, but dare not because elog
			 * tries to write to the client, which will cause problems if
			 * we have a hard communications failure ... So just write the
			 * message to the postmaster log.
			 */
			fprintf(stderr, "pq_recvbuf: recv() failed: %s\n",
					strerror(errno));
			return EOF;
		}
		if (r == 0)
		{
			/* as above, elog not safe */
			fprintf(stderr, "pq_recvbuf: unexpected EOF on client connection\n");
			return EOF;
		}
		/* r contains number of bytes read, so just incr length */
		PqRecvLength += r;
		return 0;
	}
}

/* --------------------------------
 *		pq_getbyte	- get a single byte from connection, or return EOF
 * --------------------------------
 */
static int
pq_getbyte(void)
{
	while (PqRecvPointer >= PqRecvLength)
	{
		if (pq_recvbuf())		/* If nothing in buffer, then recv some */
			return EOF;			/* Failed to recv data */
	}
	return PqRecvBuffer[PqRecvPointer++];
}

/* --------------------------------
 *		pq_peekbyte		- peek at next byte from connection
 *
 *	 Same as pq_getbyte() except we don't advance the pointer.
 * --------------------------------
 */
int
pq_peekbyte(void)
{
	while (PqRecvPointer >= PqRecvLength)
	{
		if (pq_recvbuf())		/* If nothing in buffer, then recv some */
			return EOF;			/* Failed to recv data */
	}
	return PqRecvBuffer[PqRecvPointer];
}

/* --------------------------------
 *		pq_getbytes		- get a known number of bytes from connection
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_getbytes(char *s, size_t len)
{
	size_t		amount;

	while (len > 0)
	{
		while (PqRecvPointer >= PqRecvLength)
		{
			if (pq_recvbuf())	/* If nothing in buffer, then recv some */
				return EOF;		/* Failed to recv data */
		}
		amount = PqRecvLength - PqRecvPointer;
		if (amount > len)
			amount = len;
		memcpy(s, PqRecvBuffer + PqRecvPointer, amount);
		PqRecvPointer += amount;
		s += amount;
		len -= amount;
	}
	return 0;
}

/* --------------------------------
 *		pq_getstring	- get a null terminated string from connection
 *
 *		NOTE: this routine does not do any MULTIBYTE conversion,
 *		even though it is presumably useful only for text, because
 *		no code in this module should depend on MULTIBYTE mode.
 *		See pq_getstr in pqformat.c for that.
 *
 *		FIXME: we ought to use an expansible StringInfo buffer,
 *		rather than dropping data if the message is too long.
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_getstring(char *s, size_t len)
{
	int			c;

	/*
	 * Keep on reading until we get the terminating '\0', discarding any
	 * bytes we don't have room for.
	 */

	while ((c = pq_getbyte()) != EOF && c != '\0')
	{
		if (len > 1)
		{
			*s++ = c;
			len--;
		}
	}

	*s = '\0';

	if (c == EOF)
		return EOF;

	return 0;
}


/* --------------------------------
 *		pq_putbytes		- send bytes to connection (not flushed until pq_flush)
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_putbytes(const char *s, size_t len)
{
	size_t		amount;

	while (len > 0)
	{
		if (PqSendPointer >= PQ_BUFFER_SIZE)
			if (pq_flush())		/* If buffer is full, then flush it out */
				return EOF;
		amount = PQ_BUFFER_SIZE - PqSendPointer;
		if (amount > len)
			amount = len;
		memcpy(PqSendBuffer + PqSendPointer, s, amount);
		PqSendPointer += amount;
		s += amount;
		len -= amount;
	}
	return 0;
}

/* --------------------------------
 *		pq_flush		- flush pending output
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_flush(void)
{
	unsigned char *bufptr = PqSendBuffer;
	unsigned char *bufend = PqSendBuffer + PqSendPointer;

	while (bufptr < bufend)
	{
		int			r = send(MyProcPort->sock, bufptr, bufend - bufptr, 0);

		if (r <= 0)
		{
			if (errno == EINTR)
				continue;		/* Ok if we were interrupted */

			/*
			 * We would like to use elog() here, but cannot because elog
			 * tries to write to the client, which would cause a recursive
			 * flush attempt!  So just write it out to the postmaster log.
			 */
			fprintf(stderr, "pq_flush: send() failed: %s\n",
					strerror(errno));

			/*
			 * We drop the buffered data anyway so that processing can
			 * continue, even though we'll probably quit soon.
			 */
			PqSendPointer = 0;
			return EOF;
		}
		bufptr += r;
	}
	PqSendPointer = 0;
	return 0;
}


/* --------------------------------
 * Message-level I/O routines begin here.
 *
 * These routines understand about COPY OUT protocol.
 * --------------------------------
 */


/* --------------------------------
 *		pq_putmessage	- send a normal message (suppressed in COPY OUT mode)
 *
 *		If msgtype is not '\0', it is a message type code to place before
 *		the message body (len counts only the body size!).
 *		If msgtype is '\0', then the buffer already includes the type code.
 *
 *		All normal messages are suppressed while COPY OUT is in progress.
 *		(In practice only NOTICE messages might get emitted then; dropping
 *		them is annoying, but at least they will still appear in the
 *		postmaster log.)
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_putmessage(char msgtype, const char *s, size_t len)
{
	if (DoingCopyOut)
		return 0;
	if (msgtype)
		if (pq_putbytes(&msgtype, 1))
			return EOF;
	return pq_putbytes(s, len);
}

/* --------------------------------
 *		pq_startcopyout - inform libpq that a COPY OUT transfer is beginning
 * --------------------------------
 */
void
pq_startcopyout(void)
{
	DoingCopyOut = true;
}

/* --------------------------------
 *		pq_endcopyout	- end a COPY OUT transfer
 *
 *		If errorAbort is indicated, we are aborting a COPY OUT due to an error,
 *		and must send a terminator line.  Since a partial data line might have
 *		been emitted, send a couple of newlines first (the first one could
 *		get absorbed by a backslash...)
 * --------------------------------
 */
void
pq_endcopyout(bool errorAbort)
{
	if (!DoingCopyOut)
		return;
	if (errorAbort)
		pq_putbytes("\n\n\\.\n", 5);
	/* in non-error case, copy.c will have emitted the terminator line */
	DoingCopyOut = false;
}