/* ----------
* pqReadData: read more data, if any is available
* Possible return values:
* 1: successfully loaded at least one more byte
* 0: no data is presently available, but no error detected
* -1: error detected (including EOF = connection closure);
* conn->errorMessage set
* NOTE: callers must not assume that pointers or indexes into conn->inBuffer
* remain valid across this call!
* ----------
*/
int
pqReadData(PGconn *conn)
{
int someread = 0;
int nread;
char sebuf[256];
if (conn->sock < 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("connection not open\n"));
return -1;
}
/* Left-justify any data in the buffer to make room */
if (conn->inStart < conn->inEnd)
{
if (conn->inStart > 0)
{
memmove(conn->inBuffer, conn->inBuffer + conn->inStart,
conn->inEnd - conn->inStart);
conn->inEnd -= conn->inStart;
conn->inCursor -= conn->inStart;
conn->inStart = 0;
}
}
else
{
/* buffer is logically empty, reset it */
conn->inStart = conn->inCursor = conn->inEnd = 0;
}
/*
* If the buffer is fairly full, enlarge it. We need to be able to enlarge
* the buffer in case a single message exceeds the initial buffer size. We
* enlarge before filling the buffer entirely so as to avoid asking the
* kernel for a partial packet. The magic constant here should be large
* enough for a TCP packet or Unix pipe bufferload. 8K is the usual pipe
* buffer size, so...
*/
if (conn->inBufSize - conn->inEnd < 8192)
{
if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn))
{
/*
* We don't insist that the enlarge worked, but we need some room
*/
if (conn->inBufSize - conn->inEnd < 100)
return -1; /* errorMessage already set */
}
}
/* OK, try to read some data */
retry3:
nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
conn->inBufSize - conn->inEnd);
if (nread < 0)
{
if (SOCK_ERRNO == EINTR)
goto retry3;
/* Some systems return EAGAIN/EWOULDBLOCK for no data */
#ifdef EAGAIN
if (SOCK_ERRNO == EAGAIN)
return someread;
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
if (SOCK_ERRNO == EWOULDBLOCK)
return someread;
#endif
/* We might get ECONNRESET here if using TCP and backend died */
#ifdef ECONNRESET
if (SOCK_ERRNO == ECONNRESET)
goto definitelyFailed;
#endif
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not receive data from server: %s\n"),
SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
return -1;
}
if (nread > 0)
{
conn->inEnd += nread;
/*
* Hack to deal with the fact that some kernels will only give us back
* 1 packet per recv() call, even if we asked for more and there is
* more available. If it looks like we are reading a long message,
* loop back to recv() again immediately, until we run out of data or
* buffer space. Without this, the block-and-restart behavior of
* libpq's higher levels leads to O(N^2) performance on long messages.
*
* Since we left-justified the data above, conn->inEnd gives the
* amount of data already read in the current message. We consider
* the message "long" once we have acquired 32k ...
*/
if (conn->inEnd > 32768 &&
(conn->inBufSize - conn->inEnd) >= 8192)
{
someread = 1;
goto retry3;
}
return 1;
}
if (someread)
return 1; /* got a zero read after successful tries */
/*
* A return value of 0 could mean just that no data is now available, or
* it could mean EOF --- that is, the server has closed the connection.
* Since we have the socket in nonblock mode, the only way to tell the
* difference is to see if select() is saying that the file is ready.
* Grumble. Fortunately, we don't expect this path to be taken much,
* since in normal practice we should not be trying to read data unless
* the file selected for reading already.
*
* In SSL mode it's even worse: SSL_read() could say WANT_READ and then
* data could arrive before we make the pqReadReady() test. So we must
* play dumb and assume there is more data, relying on the SSL layer to
* detect true EOF.
*/
#ifdef USE_SSL
if (conn->ssl)
return 0;
#endif
switch (pqReadReady(conn))
{
case 0:
/* definitely no data available */
return 0;
case 1:
/* ready for read */
break;
default:
goto definitelyFailed;
}
/*
* Still not sure that it's EOF, because some data could have just
* arrived.
*/
retry4:
nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
conn->inBufSize - conn->inEnd);
if (nread < 0)
{
if (SOCK_ERRNO == EINTR)
goto retry4;
/* Some systems return EAGAIN/EWOULDBLOCK for no data */
#ifdef EAGAIN
if (SOCK_ERRNO == EAGAIN)
return 0;
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
if (SOCK_ERRNO == EWOULDBLOCK)
return 0;
#endif
/* We might get ECONNRESET here if using TCP and backend died */
#ifdef ECONNRESET
if (SOCK_ERRNO == ECONNRESET)
goto definitelyFailed;
#endif
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not receive data from server: %s\n"),
SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
return -1;
}
if (nread > 0)
{
conn->inEnd += nread;
return 1;
}
/*
* OK, we are getting a zero read even though select() says ready. This
* means the connection has been closed. Cope.
*/
definitelyFailed:
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"));
conn->status = CONNECTION_BAD; /* No more connection to backend */
pqsecure_close(conn);
closesocket(conn->sock);
conn->sock = -1;
return -1;
}
/*
* 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);
}
/*
* parseInput: if appropriate, parse input data from backend
* until input is exhausted or a stopping state is reached.
* Note that this function will NOT attempt to read more data from the backend.
*/
void
pqParseInput3(PGconn *conn)
{
char id;
int msgLength;
int avail;
/*
* Loop to parse successive complete messages available in the buffer.
*/
for (;;)
{
/*
* Try to read a message. First get the type code and length. Return
* if not enough data.
*/
conn->inCursor = conn->inStart;
if (pqGetc(&id, conn))
return;
if (pqGetInt(&msgLength, 4, conn))
return;
/*
* 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);
return;
}
if (msgLength > 30000 && !VALID_LONG_MESSAGE_TYPE(id))
{
handleSyncLoss(conn, id, msgLength);
return;
}
/*
* Can't process if message body isn't all here yet.
*/
msgLength -= 4;
avail = conn->inEnd - conn->inCursor;
if (avail < msgLength)
{
/*
* Before returning, enlarge the input buffer if needed to hold
* the whole message. This is better than leaving it to
* pqReadData because we can avoid multiple cycles of realloc()
* when the message is large; also, we can implement a reasonable
* recovery strategy if we are unable to make the buffer big
* enough.
*/
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);
}
return;
}
/*
* NOTIFY and NOTICE messages can happen in any state; always process
* them right away.
*
* Most other messages should only be processed while in BUSY state.
* (In particular, in READY state we hold off further parsing until
* the application collects the current PGresult.)
*
* However, if the state is IDLE then we got trouble; we need to deal
* with the unexpected message somehow.
*
* ParameterStatus ('S') messages are a special case: in IDLE state we
* must process 'em (this case could happen if a new value was adopted
* from config file due to SIGHUP), but otherwise we hold off until
* BUSY state.
*/
if (id == 'A')
{
if (getNotify(conn))
return;
}
else if (id == 'N')
{
if (pqGetErrorNotice3(conn, false))
return;
}
else if (conn->asyncStatus != PGASYNC_BUSY)
{
/* If not IDLE state, just wait ... */
if (conn->asyncStatus != PGASYNC_IDLE)
return;
/*
* Unexpected message in IDLE state; need to recover somehow.
* ERROR messages are displayed using the notice processor;
* ParameterStatus is handled normally; anything else is just
* dropped on the floor after displaying a suitable warning
* notice. (An ERROR is very possibly the backend telling us why
* it is about to close the connection, so we don't want to just
* discard it...)
*/
if (id == 'E')
{
if (pqGetErrorNotice3(conn, false /* treat as notice */ ))
return;
}
else if (id == 'S')
{
if (getParameterStatus(conn))
return;
}
else
{
pqInternalNotice(&conn->noticeHooks,
"message type 0x%02x arrived from server while idle",
id);
/* Discard the unexpected message */
conn->inCursor += msgLength;
}
}
else
{
/*
* In BUSY state, we can process everything.
*/
switch (id)
{
case 'C': /* command complete */
if (pqGets(&conn->workBuffer, conn))
return;
if (conn->result == NULL)
{
conn->result = PQmakeEmptyPGresult(conn,
PGRES_COMMAND_OK);
if (!conn->result)
return;
}
strncpy(conn->result->cmdStatus, conn->workBuffer.data,
CMDSTATUS_LEN);
conn->asyncStatus = PGASYNC_READY;
break;
case 'E': /* error return */
if (pqGetErrorNotice3(conn, true))
return;
conn->asyncStatus = PGASYNC_READY;
break;
case 'Z': /* backend is ready for new query */
if (getReadyForQuery(conn))
return;
conn->asyncStatus = PGASYNC_IDLE;
break;
case 'I': /* empty query */
if (conn->result == NULL)
{
conn->result = PQmakeEmptyPGresult(conn,
PGRES_EMPTY_QUERY);
if (!conn->result)
return;
}
conn->asyncStatus = PGASYNC_READY;
break;
case '1': /* Parse Complete */
/* If we're doing PQprepare, we're done; else ignore */
if (conn->queryclass == PGQUERY_PREPARE)
{
if (conn->result == NULL)
{
conn->result = PQmakeEmptyPGresult(conn,
PGRES_COMMAND_OK);
if (!conn->result)
return;
}
conn->asyncStatus = PGASYNC_READY;
}
break;
case '2': /* Bind Complete */
case '3': /* Close Complete */
/* Nothing to do for these message types */
break;
case 'S': /* parameter status */
if (getParameterStatus(conn))
return;
break;
case 'K': /* secret key data from the backend */
/*
* This is expected only during backend startup, but it's
* just as easy to handle it as part of the main loop.
* Save the data and continue processing.
*/
if (pqGetInt(&(conn->be_pid), 4, conn))
return;
if (pqGetInt(&(conn->be_key), 4, conn))
return;
break;
case 'T': /* Row Description */
if (conn->result == NULL ||
conn->queryclass == PGQUERY_DESCRIBE)
{
/* First 'T' in a query sequence */
if (getRowDescriptions(conn))
return;
/*
* If we're doing a Describe, we're ready to pass the
* result back to the client.
*/
if (conn->queryclass == PGQUERY_DESCRIBE)
conn->asyncStatus = PGASYNC_READY;
}
else
{
/*
* A new 'T' message is treated as the start of
* another PGresult. (It is not clear that this is
* really possible with the current backend.) We stop
* parsing until the application accepts the current
* result.
*/
conn->asyncStatus = PGASYNC_READY;
return;
}
break;
case 'n': /* No Data */
/*
* NoData indicates that we will not be seeing a
* RowDescription message because the statement or portal
* inquired about doesn't return rows. Set up a COMMAND_OK
* result, instead of TUPLES_OK.
*/
if (conn->result == NULL)
conn->result = PQmakeEmptyPGresult(conn,
PGRES_COMMAND_OK);
/*
* If we're doing a Describe, we're ready to pass the
* result back to the client.
*/
if (conn->queryclass == PGQUERY_DESCRIBE)
conn->asyncStatus = PGASYNC_READY;
break;
case 't': /* Parameter Description */
if (getParamDescriptions(conn))
return;
break;
case 'D': /* Data Row */
if (conn->result != NULL &&
conn->result->resultStatus == PGRES_TUPLES_OK)
{
/* Read another tuple of a normal query response */
if (getAnotherTuple(conn, msgLength))
return;
}
else if (conn->result != NULL &&
conn->result->resultStatus == PGRES_FATAL_ERROR)
{
/*
* We've already choked for some reason. Just discard
* tuples till we get to the end of the query.
*/
conn->inCursor += msgLength;
}
else
{
/* Set up to report error at end of query */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("server sent data (\"D\" message) without prior row description (\"T\" message)\n"));
pqSaveErrorResult(conn);
/* Discard the unexpected message */
conn->inCursor += msgLength;
}
break;
case 'G': /* Start Copy In */
if (getCopyStart(conn, PGRES_COPY_IN))
return;
conn->asyncStatus = PGASYNC_COPY_IN;
break;
case 'H': /* Start Copy Out */
if (getCopyStart(conn, PGRES_COPY_OUT))
return;
conn->asyncStatus = PGASYNC_COPY_OUT;
conn->copy_already_done = 0;
break;
case 'd': /* Copy Data */
/*
* If we see Copy Data, just silently drop it. This would
* only occur if application exits COPY OUT mode too
* early.
*/
conn->inCursor += msgLength;
break;
case 'c': /* Copy Done */
/*
* If we see Copy Done, just silently drop it. This is
* the normal case during PQendcopy. We will keep
* swallowing data, expecting to see command-complete for
* the COPY command.
*/
break;
default:
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext(
"unexpected response from server; first received character was \"%c\"\n"),
id);
/* build an error result holding the error message */
pqSaveErrorResult(conn);
/* not sure if we will see more, so go to ready state */
conn->asyncStatus = PGASYNC_READY;
/* Discard the unexpected message */
conn->inCursor += msgLength;
break;
} /* switch on protocol character */
}
/* Successfully consumed this message */
if (conn->inCursor == conn->inStart + 5 + msgLength)
{
/* Normal case: parsing agrees with specified length */
conn->inStart = conn->inCursor;
}
else
{
/* Trouble --- report it */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("message contents do not agree with length in message type \"%c\"\n"),
id);
/* build an error result holding the error message */
pqSaveErrorResult(conn);
conn->asyncStatus = PGASYNC_READY;
/* trust the specified message length as what to skip */
conn->inStart += 5 + msgLength;
}
}
}
/*
* getCopyDataMessage - fetch next CopyData message, process async messages
*
* Returns length word of CopyData message (> 0), or 0 if no complete
* message available, -1 if end of copy, -2 if error.
*/
static int
getCopyDataMessage(PGconn *conn)
{
char id;
int msgLength;
int avail;
for (;;)
{
/*
* Do we have 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.
*/
conn->inCursor = conn->inStart;
if (pqGetc(&id, conn))
return 0;
if (pqGetInt(&msgLength, 4, conn))
return 0;
if (msgLength < 4)
{
handleSyncLoss(conn, id, msgLength);
return -2;
}
avail = conn->inEnd - conn->inCursor;
if (avail < msgLength - 4)
{
/*
* Before returning, enlarge the input buffer if needed to hold
* the whole message. See notes in parseInput.
*/
if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength - 4,
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);
return -2;
}
return 0;
}
/*
* If it's a legitimate async message type, process it. (NOTIFY
* messages are not currently possible here, but we handle them for
* completeness.) Otherwise, if it's anything except Copy Data,
* report end-of-copy.
*/
switch (id)
{
case 'A': /* NOTIFY */
if (getNotify(conn))
return 0;
break;
case 'N': /* NOTICE */
if (pqGetErrorNotice3(conn, false))
return 0;
break;
case 'S': /* ParameterStatus */
if (getParameterStatus(conn))
return 0;
break;
case 'd': /* Copy Data, pass it back to caller */
return msgLength;
default: /* treat as end of copy */
return -1;
}
/* Drop the processed message and loop around for another */
conn->inStart = conn->inCursor;
}
}