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Revise backend libpq interfaces so that messages to the frontend
can be generated in a buffer and then sent to the frontend in a single libpq call. This solves problems with NOTICE and ERROR messages generated in the middle of a data message or COPY OUT operation.
This commit is contained in:
Tom Lane
293
src/backend/libpq/pqformat.c
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293
src/backend/libpq/pqformat.c
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/*-------------------------------------------------------------------------
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*
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* pqformat.c
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* Routines for formatting and parsing frontend/backend messages
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*
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* Outgoing messages are built up in a StringInfo buffer (which is expansible)
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* and then sent in a single call to pq_putmessage. This module provides data
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* formatting/conversion routines that are needed to produce valid messages.
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* Note in particular the distinction between "raw data" and "text"; raw data
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* is message protocol characters and binary values that are not subject to
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* MULTIBYTE conversion, while text is converted by MULTIBYTE rules.
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*
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* Incoming messages are read directly off the wire, as it were, but there
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* are still data-conversion tasks to be performed.
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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* $Id: pqformat.c,v 1.1 1999/04/25 03:19:22 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* INTERFACE ROUTINES
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* Message output:
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* pq_beginmessage - initialize StringInfo buffer
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* pq_sendbyte - append a raw byte to a StringInfo buffer
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* pq_sendint - append a binary integer to a StringInfo buffer
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* pq_sendbytes - append raw data to a StringInfo buffer
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* pq_sendtext - append a text string (with MULTIBYTE conversion)
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* pq_sendstring - append a null-terminated text string (with MULTIBYTE)
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* pq_endmessage - send the completed message to the frontend
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* Note: it is also possible to append data to the StringInfo buffer using
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* the regular StringInfo routines, but this is discouraged since required
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* MULTIBYTE conversion may not occur.
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*
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* Message input:
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* pq_getint - get an integer from connection
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* pq_getstr - get a null terminated string from connection
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* pq_getnchar - get n characters from connection, and null-terminate
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* pq_getstr and pq_getnchar perform MULTIBYTE conversion on the collected
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* string. Use the raw pqcomm.c routines pq_getstring and pq_getbytes
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* to fetch data without conversion.
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*/
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#include "postgres.h"
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#include "libpq/pqformat.h"
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#include "libpq/libpq.h"
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#ifdef MULTIBYTE
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#include "mb/pg_wchar.h"
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#endif
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#ifdef HAVE_ENDIAN_H
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#include <endian.h>
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#endif
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#ifndef BYTE_ORDER
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#error BYTE_ORDER must be defined as LITTLE_ENDIAN, BIG_ENDIAN or PDP_ENDIAN
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#endif
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#if BYTE_ORDER == LITTLE_ENDIAN
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#define ntoh_s(n) n
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#define ntoh_l(n) n
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#define hton_s(n) n
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#define hton_l(n) n
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#else
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#if BYTE_ORDER == BIG_ENDIAN
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#define ntoh_s(n) (uint16)((((uint16)n & 0x00ff) << 8) | \
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(((uint16)n & 0xff00) >> 8))
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#define ntoh_l(n) (uint32)((((uint32)n & 0x000000ff) << 24) | \
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(((uint32)n & 0x0000ff00) << 8) | \
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(((uint32)n & 0x00ff0000) >> 8) | \
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(((uint32)n & 0xff000000) >> 24))
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#define hton_s(n) (ntoh_s(n))
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#define hton_l(n) (ntoh_l(n))
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#else
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#if BYTE_ORDER == PDP_ENDIAN
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#error PDP_ENDIAN macros not written yet
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#else
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#error BYTE_ORDER not defined as anything understood
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#endif
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#endif
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#endif
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/* --------------------------------
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* pq_sendbyte - append a raw byte to a StringInfo buffer
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* --------------------------------
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*/
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void
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pq_sendbyte(StringInfo buf, int byt)
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{
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appendStringInfoChar(buf, byt);
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}
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/* --------------------------------
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* pq_sendbytes - append raw data to a StringInfo buffer
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* --------------------------------
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*/
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void
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pq_sendbytes(StringInfo buf, const char *data, int datalen)
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{
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appendBinaryStringInfo(buf, data, datalen);
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}
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/* --------------------------------
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* pq_sendtext - append a text string (with MULTIBYTE conversion)
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*
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* NB: passed text string must be null-terminated, even though we expect
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* the caller to hand us the length (this is just because the caller
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* usually knows the length anyway). In this routine, the data sent to
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* the frontend is NOT null-terminated.
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* --------------------------------
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*/
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void
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pq_sendtext(StringInfo buf, const char *str, int slen)
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{
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#ifdef MULTIBYTE
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str = (const char *) pg_server_to_client(str, slen);
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#endif
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appendBinaryStringInfo(buf, str, slen);
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}
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/* --------------------------------
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* pq_sendstring - append a null-terminated text string (with MULTIBYTE)
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*
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* NB: passed text string must be null-terminated, even though we expect
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* the caller to hand us the length (this is just because the caller
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* usually knows the length anyway).
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* --------------------------------
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*/
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void
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pq_sendstring(StringInfo buf, const char *str, int slen)
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{
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#ifdef MULTIBYTE
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str = (const char *) pg_server_to_client(str, slen);
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#endif
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appendBinaryStringInfo(buf, str, slen+1);
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}
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/* --------------------------------
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* pq_sendint - append a binary integer to a StringInfo buffer
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* --------------------------------
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*/
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void
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pq_sendint(StringInfo buf, int i, int b)
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{
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unsigned char n8;
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uint16 n16;
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uint32 n32;
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switch (b)
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{
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case 1:
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n8 = (unsigned char) i;
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appendBinaryStringInfo(buf, (char *) &n8, 1);
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break;
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case 2:
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n16 = ((PG_PROTOCOL_MAJOR(FrontendProtocol) == 0) ? hton_s(i) : htons((uint16) i));
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appendBinaryStringInfo(buf, (char *) &n16, 2);
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break;
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case 4:
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n32 = ((PG_PROTOCOL_MAJOR(FrontendProtocol) == 0) ? hton_l(i) : htonl((uint32) i));
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appendBinaryStringInfo(buf, (char *) &n32, 4);
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break;
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default:
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elog(ERROR, "pq_sendint: unsupported size %d", b);
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break;
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}
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}
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/* --------------------------------
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* pq_endmessage - send the completed message to the frontend
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*
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* The data buffer is pfree()d, but if the StringInfo was allocated with
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* makeStringInfo then the caller must still pfree it.
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* --------------------------------
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*/
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void
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pq_endmessage(StringInfo buf)
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{
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if (pq_putmessage('\0', buf->data, buf->len))
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{
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snprintf(PQerrormsg, ERROR_MSG_LENGTH,
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"FATAL: pq_endmessage failed: errno=%d\n", errno);
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fputs(PQerrormsg, stderr);
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pqdebug("%s", PQerrormsg);
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}
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pfree(buf->data);
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buf->data = NULL;
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}
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/* --------------------------------
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* pq_getint - get an integer from connection
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*
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* returns 0 if OK, EOF if trouble
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* --------------------------------
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*/
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int
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pq_getint(int *result, int b)
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{
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int status;
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unsigned char n8;
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uint16 n16;
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uint32 n32;
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switch (b)
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{
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case 1:
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status = pq_getbytes((char *) &n8, 1);
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*result = (int) n8;
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break;
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case 2:
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status = pq_getbytes((char *) &n16, 2);
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*result = (int) ((PG_PROTOCOL_MAJOR(FrontendProtocol) == 0) ?
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ntoh_s(n16) : ntohs(n16));
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break;
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case 4:
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status = pq_getbytes((char *) &n32, 4);
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*result = (int) ((PG_PROTOCOL_MAJOR(FrontendProtocol) == 0) ?
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ntoh_l(n32) : ntohl(n32));
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break;
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default:
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/* if we elog(ERROR) here, we will lose sync with the frontend,
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* so just complain to postmaster log instead...
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*/
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fprintf(stderr, "pq_getint: unsupported size %d\n", b);
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status = EOF;
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*result = 0;
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break;
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}
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return status;
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}
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/* --------------------------------
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* pq_getstr - get a null terminated string from connection
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*
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* FIXME: we ought to use an expansible StringInfo buffer,
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* rather than dropping data if the message is too long.
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*
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* returns 0 if OK, EOF if trouble
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* --------------------------------
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*/
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int
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pq_getstr(char *s, int maxlen)
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{
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int c;
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#ifdef MULTIBYTE
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char *p;
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#endif
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c = pq_getstring(s, maxlen);
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#ifdef MULTIBYTE
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p = (char*) pg_client_to_server((unsigned char *) s, maxlen);
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if (s != p) /* actual conversion has been done? */
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strcpy(s, p);
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#endif
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return c;
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}
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/* --------------------------------
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* pq_getnchar - get n characters from connection, and null-terminate
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*
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* returns 0 if OK, EOF if trouble
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* --------------------------------
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*/
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int
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pq_getnchar(char *s, int len)
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{
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int c;
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#ifdef MULTIBYTE
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char *p;
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#endif
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c = pq_getbytes(s, len);
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s[len] = '\0';
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#ifdef MULTIBYTE
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p = (char*) pg_client_to_server((unsigned char *) s, len+1);
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if (s != p) /* actual conversion has been done? */
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strcpy(s, p);
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#endif
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return c;
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}
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