/*
* PQgetline - gets a newline-terminated string from the backend.
*
* See fe-exec.c for documentation.
*/
int
pqGetline2(PGconn *conn, char *s, int maxlen)
{
int result = 1; /* return value if buffer overflows */
if (conn->sock == PGINVALID_SOCKET ||
conn->asyncStatus != PGASYNC_COPY_OUT)
{
*s = '\0';
return EOF;
}
/*
* Since this is a purely synchronous routine, we don't bother to maintain
* conn->inCursor; there is no need to back up.
*/
while (maxlen > 1)
{
if (conn->inStart < conn->inEnd)
{
char c = conn->inBuffer[conn->inStart++];
if (c == '\n')
{
result = 0; /* success exit */
break;
}
*s++ = c;
maxlen--;
}
else
{
/* need to load more data */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
{
result = EOF;
break;
}
}
}
*s = '\0';
return result;
}
/*
* PQgetline - gets a newline-terminated string from the backend.
*
* See fe-exec.c for documentation.
*/
int
pqGetline3(PGconn *conn, char *s, int maxlen)
{
int status;
if (conn->sock < 0 ||
conn->asyncStatus != PGASYNC_COPY_OUT ||
conn->copy_is_binary)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("PQgetline: not doing text COPY OUT\n"));
*s = '\0';
return EOF;
}
while ((status = PQgetlineAsync(conn, s, maxlen - 1)) == 0)
{
/* need to load more data */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
{
*s = '\0';
return EOF;
}
}
if (status < 0)
{
/* End of copy detected; gin up old-style terminator */
strcpy(s, "\\.");
return 0;
}
/* Add null terminator, and strip trailing \n if present */
if (s[status - 1] == '\n')
{
s[status - 1] = '\0';
return 0;
}
else
{
s[status] = '\0';
return 1;
}
}
/*
* pqSendSome: send data waiting in the output buffer.
*
* len is how much to try to send (typically equal to outCount, but may
* be less).
*
* Return 0 on success, -1 on failure and 1 when not all data could be sent
* because the socket would block and the connection is non-blocking.
*/
static int
pqSendSome(PGconn *conn, int len)
{
char *ptr = conn->outBuffer;
int remaining = conn->outCount;
int result = 0;
if (conn->sock < 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("connection not open\n"));
return -1;
}
/* while there's still data to send */
while (len > 0)
{
int sent;
char sebuf[256];
#ifndef WIN32
sent = pqsecure_write(conn, ptr, len);
#else
/*
* Windows can fail on large sends, per KB article Q201213. The
* failure-point appears to be different in different versions of
* Windows, but 64k should always be safe.
*/
sent = pqsecure_write(conn, ptr, Min(len, 65536));
#endif
if (sent < 0)
{
/*
* Anything except EAGAIN/EWOULDBLOCK/EINTR is trouble. If it's
* EPIPE or ECONNRESET, assume we've lost the backend connection
* permanently.
*/
switch (SOCK_ERRNO)
{
#ifdef EAGAIN
case EAGAIN:
break;
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
case EWOULDBLOCK:
break;
#endif
case EINTR:
continue;
case EPIPE:
#ifdef ECONNRESET
case ECONNRESET:
#endif
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext(
"server closed the connection unexpectedly\n"
"\tThis probably means the server terminated abnormally\n"
"\tbefore or while processing the request.\n"));
/*
* We used to close the socket here, but that's a bad idea
* since there might be unread data waiting (typically, a
* NOTICE message from the backend telling us it's
* committing hara-kiri...). Leave the socket open until
* pqReadData finds no more data can be read. But abandon
* attempt to send data.
*/
conn->outCount = 0;
return -1;
default:
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not send data to server: %s\n"),
SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
/* We don't assume it's a fatal error... */
conn->outCount = 0;
return -1;
}
}
else
{
ptr += sent;
len -= sent;
remaining -= sent;
}
if (len > 0)
{
/*
* We didn't send it all, wait till we can send more.
*
* If the connection is in non-blocking mode we don't wait, but
* return 1 to indicate that data is still pending.
*/
if (pqIsnonblocking(conn))
{
result = 1;
break;
}
/*
* There are scenarios in which we can't send data because the
* communications channel is full, but we cannot expect the server
* to clear the channel eventually because it's blocked trying to
* send data to us. (This can happen when we are sending a large
* amount of COPY data, and the server has generated lots of
* NOTICE responses.) To avoid a deadlock situation, we must be
* prepared to accept and buffer incoming data before we try
* again. Furthermore, it is possible that such incoming data
* might not arrive until after we've gone to sleep. Therefore,
* we wait for either read ready or write ready.
*/
if (pqReadData(conn) < 0)
{
result = -1; /* error message already set up */
break;
}
if (pqWait(TRUE, TRUE, conn))
{
result = -1;
break;
}
}
}
/* shift the remaining contents of the buffer */
if (remaining > 0)
memmove(conn->outBuffer, ptr, remaining);
conn->outCount = remaining;
return result;
}
/*
* pqSetenvPoll
*
* Polls the process of passing the values of a standard set of environment
* variables to the backend.
*/
PostgresPollingStatusType
pqSetenvPoll(PGconn *conn)
{
PGresult *res;
if (conn == NULL || conn->status == CONNECTION_BAD)
return PGRES_POLLING_FAILED;
/* Check whether there are any data for us */
switch (conn->setenv_state)
{
/* These are reading states */
case SETENV_STATE_CLIENT_ENCODING_WAIT:
case SETENV_STATE_OPTION_WAIT:
case SETENV_STATE_QUERY1_WAIT:
case SETENV_STATE_QUERY2_WAIT:
{
/* Load waiting data */
int n = pqReadData(conn);
if (n < 0)
goto error_return;
if (n == 0)
return PGRES_POLLING_READING;
break;
}
/* These are writing states, so we just proceed. */
case SETENV_STATE_CLIENT_ENCODING_SEND:
case SETENV_STATE_OPTION_SEND:
case SETENV_STATE_QUERY1_SEND:
case SETENV_STATE_QUERY2_SEND:
break;
/* Should we raise an error if called when not active? */
case SETENV_STATE_IDLE:
return PGRES_POLLING_OK;
default:
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext(
"invalid setenv state %c, "
"probably indicative of memory corruption\n"
),
conn->setenv_state);
goto error_return;
}
/* We will loop here until there is nothing left to do in this call. */
for (;;)
{
switch (conn->setenv_state)
{
/*
* The _CLIENT_ENCODING_SEND code is slightly different from
* _OPTION_SEND below (e.g., no getenv() call), which is why a
* different state is used.
*/
case SETENV_STATE_CLIENT_ENCODING_SEND:
{
char setQuery[100]; /* note length limit in
* sprintf below */
const char *val = conn->client_encoding_initial;
if (val)
{
if (pg_strcasecmp(val, "default") == 0)
sprintf(setQuery, "SET client_encoding = DEFAULT");
else
sprintf(setQuery, "SET client_encoding = '%.60s'",
val);
#ifdef CONNECTDEBUG
fprintf(stderr,
"Sending client_encoding with %s\n",
setQuery);
#endif
if (!PQsendQuery(conn, setQuery))
goto error_return;
conn->setenv_state = SETENV_STATE_CLIENT_ENCODING_WAIT;
}
else
conn->setenv_state = SETENV_STATE_OPTION_SEND;
break;
}
case SETENV_STATE_OPTION_SEND:
{
/*
* Send SET commands for stuff directed by Environment
* Options. Note: we assume that SET commands won't start
* transaction blocks, even in a 7.3 server with
* autocommit off.
*/
char setQuery[100]; /* note length limit in
* sprintf below */
if (conn->next_eo->envName)
{
const char *val;
if ((val = getenv(conn->next_eo->envName)))
{
if (pg_strcasecmp(val, "default") == 0)
sprintf(setQuery, "SET %s = DEFAULT",
conn->next_eo->pgName);
else
sprintf(setQuery, "SET %s = '%.60s'",
conn->next_eo->pgName, val);
#ifdef CONNECTDEBUG
fprintf(stderr,
"Use environment variable %s to send %s\n",
conn->next_eo->envName, setQuery);
#endif
if (!PQsendQuery(conn, setQuery))
goto error_return;
conn->setenv_state = SETENV_STATE_OPTION_WAIT;
}
else
conn->next_eo++;
}
else
{
/* No more options to send, so move on to querying */
conn->setenv_state = SETENV_STATE_QUERY1_SEND;
}
break;
}
case SETENV_STATE_CLIENT_ENCODING_WAIT:
{
if (PQisBusy(conn))
return PGRES_POLLING_READING;
res = PQgetResult(conn);
if (res)
{
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
PQclear(res);
goto error_return;
}
PQclear(res);
/* Keep reading until PQgetResult returns NULL */
}
else
{
/* Query finished, so send the next option */
conn->setenv_state = SETENV_STATE_OPTION_SEND;
}
break;
}
case SETENV_STATE_OPTION_WAIT:
{
if (PQisBusy(conn))
return PGRES_POLLING_READING;
res = PQgetResult(conn);
if (res)
{
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
PQclear(res);
goto error_return;
}
PQclear(res);
/* Keep reading until PQgetResult returns NULL */
}
else
{
/* Query finished, so send the next option */
conn->next_eo++;
conn->setenv_state = SETENV_STATE_OPTION_SEND;
}
break;
}
case SETENV_STATE_QUERY1_SEND:
{
/*
* Issue query to get information we need. Here we must
* use begin/commit in case autocommit is off by default
* in a 7.3 server.
*
* Note: version() exists in all protocol-2.0-supporting
* backends. In 7.3 it would be safer to write
* pg_catalog.version(), but we can't do that without
* causing problems on older versions.
*/
if (!PQsendQuery(conn, "begin; select version(); end"))
goto error_return;
conn->setenv_state = SETENV_STATE_QUERY1_WAIT;
return PGRES_POLLING_READING;
}
case SETENV_STATE_QUERY1_WAIT:
{
if (PQisBusy(conn))
return PGRES_POLLING_READING;
res = PQgetResult(conn);
if (res)
{
char *val;
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/* ignore begin/commit command results */
PQclear(res);
continue;
}
if (PQresultStatus(res) != PGRES_TUPLES_OK ||
PQntuples(res) != 1)
{
PQclear(res);
goto error_return;
}
/*
* Extract server version and save as if
* ParameterStatus
*/
val = PQgetvalue(res, 0, 0);
if (val && strncmp(val, "PostgreSQL ", 11) == 0)
{
char *ptr;
/* strip off PostgreSQL part */
val += 11;
/*
* strip off platform part (scribbles on result,
* naughty naughty)
*/
ptr = strchr(val, ' ');
if (ptr)
*ptr = '\0';
pqSaveParameterStatus(conn, "server_version",
val);
}
PQclear(res);
/* Keep reading until PQgetResult returns NULL */
}
else
{
/* Query finished, move to next */
conn->setenv_state = SETENV_STATE_QUERY2_SEND;
}
break;
}
case SETENV_STATE_QUERY2_SEND:
{
const char *query;
/*
* pg_client_encoding does not exist in pre-7.2 servers.
* So we need to be prepared for an error here. Do *not*
* start a transaction block, except in 7.3 servers where
* we need to prevent autocommit-off from starting a
* transaction anyway.
*/
if (conn->sversion >= 70300 &&
conn->sversion < 70400)
query = "begin; select pg_catalog.pg_client_encoding(); end";
else
query = "select pg_client_encoding()";
if (!PQsendQuery(conn, query))
goto error_return;
conn->setenv_state = SETENV_STATE_QUERY2_WAIT;
return PGRES_POLLING_READING;
}
case SETENV_STATE_QUERY2_WAIT:
{
if (PQisBusy(conn))
return PGRES_POLLING_READING;
res = PQgetResult(conn);
if (res)
{
const char *val;
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/* ignore begin/commit command results */
PQclear(res);
continue;
}
if (PQresultStatus(res) == PGRES_TUPLES_OK &&
PQntuples(res) == 1)
{
/* Extract client encoding and save it */
val = PQgetvalue(res, 0, 0);
if (val && *val) /* null should not happen, but */
pqSaveParameterStatus(conn, "client_encoding",
val);
}
else
{
/*
* Error: presumably function not available, so
* use PGCLIENTENCODING or SQL_ASCII as the
* fallback.
*/
val = getenv("PGCLIENTENCODING");
if (val && *val)
pqSaveParameterStatus(conn, "client_encoding",
val);
else
pqSaveParameterStatus(conn, "client_encoding",
"SQL_ASCII");
}
PQclear(res);
/* Keep reading until PQgetResult returns NULL */
}
else
{
/* Query finished, so we're done */
conn->setenv_state = SETENV_STATE_IDLE;
return PGRES_POLLING_OK;
}
break;
}
default:
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("invalid state %c, "
"probably indicative of memory corruption\n"),
conn->setenv_state);
goto error_return;
}
}
/* Unreachable */
error_return:
conn->setenv_state = SETENV_STATE_IDLE;
return PGRES_POLLING_FAILED;
}
/*
* PQfn - Send a function call to the POSTGRES backend.
*
* See fe-exec.c for documentation.
*/
PGresult *
pqFunctionCall2(PGconn *conn, Oid fnid,
int *result_buf, int *actual_result_len,
int result_is_int,
const PQArgBlock *args, int nargs)
{
bool needInput = false;
ExecStatusType status = PGRES_FATAL_ERROR;
char id;
int i;
/* PQfn already validated connection state */
if (pqPutMsgStart('F', false, conn) < 0 || /* function call msg */
pqPuts(" ", conn) < 0 || /* dummy string */
pqPutInt(fnid, 4, conn) != 0 || /* function id */
pqPutInt(nargs, 4, conn) != 0) /* # of args */
{
pqHandleSendFailure(conn);
return NULL;
}
for (i = 0; i < nargs; ++i)
{ /* len.int4 + contents */
if (pqPutInt(args[i].len, 4, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
if (args[i].isint)
{
if (pqPutInt(args[i].u.integer, 4, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
}
else
{
if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
}
}
if (pqPutMsgEnd(conn) < 0 ||
pqFlush(conn))
{
pqHandleSendFailure(conn);
return NULL;
}
for (;;)
{
if (needInput)
{
/* Wait for some data to arrive (or for the channel to close) */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
break;
}
/*
* Scan the message. If we run out of data, loop around to try again.
*/
conn->inCursor = conn->inStart;
needInput = true;
if (pqGetc(&id, conn))
continue;
/*
* We should see V or E response to the command, but might get N
* and/or A notices first. We also need to swallow the final Z before
* returning.
*/
switch (id)
{
case 'V': /* function result */
if (pqGetc(&id, conn))
continue;
if (id == 'G')
{
/* function returned nonempty value */
if (pqGetInt(actual_result_len, 4, conn))
continue;
if (result_is_int)
{
if (pqGetInt(result_buf, 4, conn))
continue;
}
else
{
if (pqGetnchar((char *) result_buf,
*actual_result_len,
conn))
continue;
}
if (pqGetc(&id, conn)) /* get the last '0' */
continue;
}
if (id == '0')
{
/* correctly finished function result message */
status = PGRES_COMMAND_OK;
}
else
{
/* The backend violates the protocol. */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("protocol error: id=0x%x\n"),
id);
pqSaveErrorResult(conn);
conn->inStart = conn->inCursor;
return pqPrepareAsyncResult(conn);
}
break;
case 'E': /* error return */
if (pqGetErrorNotice2(conn, true))
continue;
status = PGRES_FATAL_ERROR;
break;
case 'A': /* notify message */
/* handle notify and go back to processing return values */
if (getNotify(conn))
continue;
break;
case 'N': /* notice */
/* handle notice and go back to processing return values */
if (pqGetErrorNotice2(conn, false))
continue;
break;
case 'Z': /* backend is ready for new query */
/* consume the message and exit */
conn->inStart = conn->inCursor;
/* if we saved a result object (probably an error), use it */
if (conn->result)
return pqPrepareAsyncResult(conn);
return PQmakeEmptyPGresult(conn, status);
default:
/* The backend violates the protocol. */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("protocol error: id=0x%x\n"),
id);
pqSaveErrorResult(conn);
conn->inStart = conn->inCursor;
return pqPrepareAsyncResult(conn);
}
/* Completed this message, keep going */
conn->inStart = conn->inCursor;
needInput = false;
}
/*
* We fall out of the loop only upon failing to read data.
* conn->errorMessage has been set by pqWait or pqReadData. We want to
* append it to any already-received error message.
*/
pqSaveErrorResult(conn);
return pqPrepareAsyncResult(conn);
}
/*
* 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
pqGetCopyData2(PGconn *conn, char **buffer, int async)
{
bool found;
int msgLength;
for (;;)
{
/*
* Do we have a complete line of data?
*/
conn->inCursor = conn->inStart;
found = false;
while (conn->inCursor < conn->inEnd)
{
char c = conn->inBuffer[conn->inCursor++];
if (c == '\n')
{
found = true;
break;
}
}
if (!found)
goto nodata;
msgLength = conn->inCursor - conn->inStart;
/*
* If it's the end-of-data marker, consume it, exit COPY_OUT mode, and
* let caller read status with PQgetResult().
*/
if (msgLength == 3 &&
strncmp(&conn->inBuffer[conn->inStart], "\\.\n", 3) == 0)
{
conn->inStart = conn->inCursor;
conn->asyncStatus = PGASYNC_BUSY;
return -1;
}
/*
* Pass the line back to the caller.
*/
*buffer = (char *) malloc(msgLength + 1);
if (*buffer == NULL)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("out of memory\n"));
return -2;
}
memcpy(*buffer, &conn->inBuffer[conn->inStart], msgLength);
(*buffer)[msgLength] = '\0'; /* Add terminating null */
/* Mark message consumed */
conn->inStart = conn->inCursor;
return msgLength;
nodata:
/* Don't block if async read requested */
if (async)
return 0;
/* Need to load more data */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
return -2;
}
}
/*
* PQfn - Send a function call to the POSTGRES backend.
*
* See fe-exec.c for documentation.
*/
PGresult *
pqFunctionCall3(PGconn *conn, Oid fnid,
int *result_buf, int *actual_result_len,
int result_is_int,
const PQArgBlock *args, int nargs)
{
bool needInput = false;
ExecStatusType status = PGRES_FATAL_ERROR;
char id;
int msgLength;
int avail;
int i;
/* PQfn already validated connection state */
if (pqPutMsgStart('F', false, conn) < 0 || /* function call msg */
pqPutInt(fnid, 4, conn) < 0 || /* function id */
pqPutInt(1, 2, conn) < 0 || /* # of format codes */
pqPutInt(1, 2, conn) < 0 || /* format code: BINARY */
pqPutInt(nargs, 2, conn) < 0) /* # of args */
{
pqHandleSendFailure(conn);
return NULL;
}
for (i = 0; i < nargs; ++i)
{ /* len.int4 + contents */
if (pqPutInt(args[i].len, 4, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
if (args[i].len == -1)
continue; /* it's NULL */
if (args[i].isint)
{
if (pqPutInt(args[i].u.integer, args[i].len, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
}
else
{
if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
{
pqHandleSendFailure(conn);
return NULL;
}
}
}
if (pqPutInt(1, 2, conn) < 0) /* result format code: BINARY */
{
pqHandleSendFailure(conn);
return NULL;
}
if (pqPutMsgEnd(conn) < 0 ||
pqFlush(conn))
{
pqHandleSendFailure(conn);
return NULL;
}
for (;;)
{
if (needInput)
{
/* Wait for some data to arrive (or for the channel to close) */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
break;
}
/*
* Scan the message. If we run out of data, loop around to try again.
*/
needInput = true;
conn->inCursor = conn->inStart;
if (pqGetc(&id, conn))
continue;
if (pqGetInt(&msgLength, 4, conn))
continue;
/*
* Try to validate message type/length here. A length less than 4 is
* definitely broken. Large lengths should only be believed for a few
* message types.
*/
if (msgLength < 4)
{
handleSyncLoss(conn, id, msgLength);
break;
}
if (msgLength > 30000 && !VALID_LONG_MESSAGE_TYPE(id))
{
handleSyncLoss(conn, id, msgLength);
break;
}
/*
* Can't process if message body isn't all here yet.
*/
msgLength -= 4;
avail = conn->inEnd - conn->inCursor;
if (avail < msgLength)
{
/*
* Before looping, enlarge the input buffer if needed to hold the
* whole message. See notes in parseInput.
*/
if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
{
/*
* XXX add some better recovery code... plan is to skip over
* the message using its length, then report an error. For the
* moment, just treat this like loss of sync (which indeed it
* might be!)
*/
handleSyncLoss(conn, id, msgLength);
break;
}
continue;
}
/*
* We should see V or E response to the command, but might get N
* and/or A notices first. We also need to swallow the final Z before
* returning.
*/
switch (id)
{
case 'V': /* function result */
if (pqGetInt(actual_result_len, 4, conn))
continue;
if (*actual_result_len != -1)
{
if (result_is_int)
{
if (pqGetInt(result_buf, *actual_result_len, conn))
continue;
}
else
{
if (pqGetnchar((char *) result_buf,
*actual_result_len,
conn))
continue;
}
}
/* correctly finished function result message */
status = PGRES_COMMAND_OK;
break;
case 'E': /* error return */
if (pqGetErrorNotice3(conn, true))
continue;
status = PGRES_FATAL_ERROR;
break;
case 'A': /* notify message */
/* handle notify and go back to processing return values */
if (getNotify(conn))
continue;
break;
case 'N': /* notice */
/* handle notice and go back to processing return values */
if (pqGetErrorNotice3(conn, false))
continue;
break;
case 'Z': /* backend is ready for new query */
if (getReadyForQuery(conn))
continue;
/* consume the message and exit */
conn->inStart += 5 + msgLength;
/* if we saved a result object (probably an error), use it */
if (conn->result)
return pqPrepareAsyncResult(conn);
return PQmakeEmptyPGresult(conn, status);
case 'S': /* parameter status */
if (getParameterStatus(conn))
continue;
break;
default:
/* The backend violates the protocol. */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("protocol error: id=0x%x\n"),
id);
pqSaveErrorResult(conn);
/* trust the specified message length as what to skip */
conn->inStart += 5 + msgLength;
return pqPrepareAsyncResult(conn);
}
/* Completed this message, keep going */
/* trust the specified message length as what to skip */
conn->inStart += 5 + msgLength;
needInput = false;
}
/*
* We fall out of the loop only upon failing to read data.
* conn->errorMessage has been set by pqWait or pqReadData. We want to
* append it to any already-received error message.
*/
pqSaveErrorResult(conn);
return pqPrepareAsyncResult(conn);
}
/*
* 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
pqGetCopyData3(PGconn *conn, char **buffer, int async)
{
int msgLength;
for (;;)
{
/*
* Collect the next input message. To make life simpler for async
* callers, we keep returning 0 until the next message is fully
* available, even if it is not Copy Data.
*/
msgLength = getCopyDataMessage(conn);
if (msgLength < 0)
{
/*
* On end-of-copy, exit COPY_OUT mode and let caller read status
* with PQgetResult(). The normal case is that it's Copy Done,
* but we let parseInput read that. If error, we expect the
* state was already changed.
*/
if (msgLength == -1)
conn->asyncStatus = PGASYNC_BUSY;
return msgLength; /* end-of-copy or error */
}
if (msgLength == 0)
{
/* Don't block if async read requested */
if (async)
return 0;
/* Need to load more data */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
return -2;
continue;
}
/*
* Drop zero-length messages (shouldn't happen anyway). Otherwise
* pass the data back to the caller.
*/
msgLength -= 4;
if (msgLength > 0)
{
*buffer = (char *) malloc(msgLength + 1);
if (*buffer == NULL)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("out of memory\n"));
return -2;
}
memcpy(*buffer, &conn->inBuffer[conn->inCursor], msgLength);
(*buffer)[msgLength] = '\0'; /* Add terminating null */
/* Mark message consumed */
conn->inStart = conn->inCursor + msgLength;
return msgLength;
}
/* Empty, so drop it and loop around for another */
conn->inStart = conn->inCursor;
}
}
/*
* pqSendSome: send data waiting in the output buffer.
*
* len is how much to try to send (typically equal to outCount, but may
* be less).
*
* Return 0 on success, -1 on failure and 1 when not all data could be sent
* because the socket would block and the connection is non-blocking.
*/
static int
pqSendSome(PGconn *conn, int len)
{
char *ptr = conn->outBuffer;
int remaining = conn->outCount;
int result = 0;
if (conn->sock == PGINVALID_SOCKET)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("connection not open\n"));
/* Discard queued data; no chance it'll ever be sent */
conn->outCount = 0;
return -1;
}
/* while there's still data to send */
while (len > 0)
{
int sent;
#ifndef WIN32
sent = pqsecure_write(conn, ptr, len);
#else
/*
* Windows can fail on large sends, per KB article Q201213. The
* failure-point appears to be different in different versions of
* Windows, but 64k should always be safe.
*/
sent = pqsecure_write(conn, ptr, Min(len, 65536));
#endif
if (sent < 0)
{
/* Anything except EAGAIN/EWOULDBLOCK/EINTR is trouble */
switch (SOCK_ERRNO)
{
#ifdef EAGAIN
case EAGAIN:
break;
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
case EWOULDBLOCK:
break;
#endif
case EINTR:
continue;
default:
/* pqsecure_write set the error message for us */
/*
* We used to close the socket here, but that's a bad idea
* since there might be unread data waiting (typically, a
* NOTICE message from the backend telling us it's
* committing hara-kiri...). Leave the socket open until
* pqReadData finds no more data can be read. But abandon
* attempt to send data.
*/
conn->outCount = 0;
return -1;
}
}
else
{
ptr += sent;
len -= sent;
remaining -= sent;
}
if (len > 0)
{
/*
* We didn't send it all, wait till we can send more.
*
* There are scenarios in which we can't send data because the
* communications channel is full, but we cannot expect the server
* to clear the channel eventually because it's blocked trying to
* send data to us. (This can happen when we are sending a large
* amount of COPY data, and the server has generated lots of
* NOTICE responses.) To avoid a deadlock situation, we must be
* prepared to accept and buffer incoming data before we try
* again. Furthermore, it is possible that such incoming data
* might not arrive until after we've gone to sleep. Therefore,
* we wait for either read ready or write ready.
*
* In non-blocking mode, we don't wait here directly, but return
* 1 to indicate that data is still pending. The caller should
* wait for both read and write ready conditions, and call
* PQconsumeInput() on read ready, but just in case it doesn't, we
* call pqReadData() ourselves before returning. That's not
* enough if the data has not arrived yet, but it's the best we
* can do, and works pretty well in practice. (The documentation
* used to say that you only need to wait for write-ready, so
* there are still plenty of applications like that out there.)
*/
if (pqReadData(conn) < 0)
{
result = -1; /* error message already set up */
break;
}
if (pqIsnonblocking(conn))
{
result = 1;
break;
}
if (pqWait(TRUE, TRUE, conn))
{
result = -1;
break;
}
}
}
/* shift the remaining contents of the buffer */
if (remaining > 0)
memmove(conn->outBuffer, ptr, remaining);
conn->outCount = remaining;
return result;
}