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postgresql/src/interfaces/libpq/fe-exec.c

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/*-------------------------------------------------------------------------
*
* fe-exec.c
* functions related to sending a query down to the backend
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.96 2000/06/14 18:17:58 petere Exp $
*
*-------------------------------------------------------------------------
*/
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include "postgres.h"
#include "libpq-fe.h"
#include "libpq-int.h"
#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#endif
/* keep this in same order as ExecStatusType in libpq-fe.h */
char *const pgresStatus[] = {
"PGRES_EMPTY_QUERY",
"PGRES_COMMAND_OK",
"PGRES_TUPLES_OK",
"PGRES_COPY_OUT",
"PGRES_COPY_IN",
"PGRES_BAD_RESPONSE",
"PGRES_NONFATAL_ERROR",
"PGRES_FATAL_ERROR"
};
/* Note: DONOTICE macro will work if applied to either PGconn or PGresult */
#define DONOTICE(conn,message) \
((*(conn)->noticeHook) ((conn)->noticeArg, (message)))
static void pqCatenateResultError(PGresult *res, const char *msg);
static void saveErrorResult(PGconn *conn);
static PGresult *prepareAsyncResult(PGconn *conn);
static int addTuple(PGresult *res, PGresAttValue * tup);
static void parseInput(PGconn *conn);
static void handleSendFailure(PGconn *conn);
static int getRowDescriptions(PGconn *conn);
static int getAnotherTuple(PGconn *conn, int binary);
static int getNotify(PGconn *conn);
static int getNotice(PGconn *conn);
/* ----------------
* Space management for PGresult.
*
* Formerly, libpq did a separate malloc() for each field of each tuple
* returned by a query. This was remarkably expensive --- malloc/free
* consumed a sizable part of the application's runtime. And there is
* no real need to keep track of the fields separately, since they will
* all be freed together when the PGresult is released. So now, we grab
* large blocks of storage from malloc and allocate space for query data
* within these blocks, using a trivially simple allocator. This reduces
* the number of malloc/free calls dramatically, and it also avoids
* fragmentation of the malloc storage arena.
* The PGresult structure itself is still malloc'd separately. We could
* combine it with the first allocation block, but that would waste space
* for the common case that no extra storage is actually needed (that is,
* the SQL command did not return tuples).
* We also malloc the top-level array of tuple pointers separately, because
* we need to be able to enlarge it via realloc, and our trivial space
* allocator doesn't handle that effectively. (Too bad the FE/BE protocol
* doesn't tell us up front how many tuples will be returned.)
* All other subsidiary storage for a PGresult is kept in PGresult_data blocks
* of size PGRESULT_DATA_BLOCKSIZE. The overhead at the start of each block
* is just a link to the next one, if any. Free-space management info is
* kept in the owning PGresult.
* A query returning a small amount of data will thus require three malloc
* calls: one for the PGresult, one for the tuples pointer array, and one
* PGresult_data block.
* Only the most recently allocated PGresult_data block is a candidate to
* have more stuff added to it --- any extra space left over in older blocks
* is wasted. We could be smarter and search the whole chain, but the point
* here is to be simple and fast. Typical applications do not keep a PGresult
* around very long anyway, so some wasted space within one is not a problem.
*
* Tuning constants for the space allocator are:
* PGRESULT_DATA_BLOCKSIZE: size of a standard allocation block, in bytes
* PGRESULT_ALIGN_BOUNDARY: assumed alignment requirement for binary data
* PGRESULT_SEP_ALLOC_THRESHOLD: objects bigger than this are given separate
* blocks, instead of being crammed into a regular allocation block.
* Requirements for correct function are:
* PGRESULT_ALIGN_BOUNDARY must be a multiple of the alignment requirements
* of all machine data types. (Currently this is set from configure
* tests, so it should be OK automatically.)
* PGRESULT_SEP_ALLOC_THRESHOLD + PGRESULT_BLOCK_OVERHEAD <=
* PGRESULT_DATA_BLOCKSIZE
* pqResultAlloc assumes an object smaller than the threshold will fit
* in a new block.
* The amount of space wasted at the end of a block could be as much as
* PGRESULT_SEP_ALLOC_THRESHOLD, so it doesn't pay to make that too large.
* ----------------
*/
#ifdef MAX
#undef MAX
#endif
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define PGRESULT_DATA_BLOCKSIZE 2048
#define PGRESULT_ALIGN_BOUNDARY MAXIMUM_ALIGNOF /* from configure */
#define PGRESULT_BLOCK_OVERHEAD MAX(sizeof(PGresult_data), PGRESULT_ALIGN_BOUNDARY)
#define PGRESULT_SEP_ALLOC_THRESHOLD (PGRESULT_DATA_BLOCKSIZE / 2)
/*
* PQmakeEmptyPGresult
* returns a newly allocated, initialized PGresult with given status.
* If conn is not NULL and status indicates an error, the conn's
* errorMessage is copied.
*
* Note this is exported --- you wouldn't think an application would need
* to build its own PGresults, but this has proven useful in both libpgtcl
* and the Perl5 interface, so maybe it's not so unreasonable.
*/
PGresult *
PQmakeEmptyPGresult(PGconn *conn, ExecStatusType status)
{
PGresult *result;
result = (PGresult *) malloc(sizeof(PGresult));
result->xconn = conn; /* might be NULL */
result->ntups = 0;
result->numAttributes = 0;
result->attDescs = NULL;
result->tuples = NULL;
result->tupArrSize = 0;
result->resultStatus = status;
result->cmdStatus[0] = '\0';
result->binary = 0;
result->errMsg = NULL;
result->null_field[0] = '\0';
result->curBlock = NULL;
result->curOffset = 0;
result->spaceLeft = 0;
if (conn)
{
/* copy connection data we might need for operations on PGresult */
result->noticeHook = conn->noticeHook;
result->noticeArg = conn->noticeArg;
result->client_encoding = conn->client_encoding;
/* consider copying conn's errorMessage */
switch (status)
{
case PGRES_EMPTY_QUERY:
case PGRES_COMMAND_OK:
case PGRES_TUPLES_OK:
case PGRES_COPY_OUT:
case PGRES_COPY_IN:
/* non-error cases */
break;
default:
pqSetResultError(result, conn->errorMessage.data);
break;
}
}
else
{
/* defaults... */
result->noticeHook = NULL;
result->noticeArg = NULL;
result->client_encoding = 0; /* should be SQL_ASCII */
}
return result;
}
/*
* pqResultAlloc -
* Allocate subsidiary storage for a PGresult.
*
* nBytes is the amount of space needed for the object.
* If isBinary is true, we assume that we need to align the object on
* a machine allocation boundary.
* If isBinary is false, we assume the object is a char string and can
* be allocated on any byte boundary.
*/
void *
pqResultAlloc(PGresult *res, size_t nBytes, bool isBinary)
{
char *space;
PGresult_data *block;
if (!res)
return NULL;
if (nBytes <= 0)
return res->null_field;
/*
* If alignment is needed, round up the current position to an
* alignment boundary.
*/
if (isBinary)
{
int offset = res->curOffset % PGRESULT_ALIGN_BOUNDARY;
if (offset)
{
res->curOffset += PGRESULT_ALIGN_BOUNDARY - offset;
res->spaceLeft -= PGRESULT_ALIGN_BOUNDARY - offset;
}
}
/* If there's enough space in the current block, no problem. */
if (nBytes <= res->spaceLeft)
{
space = res->curBlock->space + res->curOffset;
res->curOffset += nBytes;
res->spaceLeft -= nBytes;
return space;
}
/*
* If the requested object is very large, give it its own block; this
* avoids wasting what might be most of the current block to start a
* new block. (We'd have to special-case requests bigger than the
* block size anyway.) The object is always given binary alignment in
* this case.
*/
if (nBytes >= PGRESULT_SEP_ALLOC_THRESHOLD)
{
block = (PGresult_data *) malloc(nBytes + PGRESULT_BLOCK_OVERHEAD);
if (!block)
return NULL;
space = block->space + PGRESULT_BLOCK_OVERHEAD;
if (res->curBlock)
{
/*
* Tuck special block below the active block, so that we don't
* have to waste the free space in the active block.
*/
block->next = res->curBlock->next;
res->curBlock->next = block;
}
else
{
/* Must set up the new block as the first active block. */
block->next = NULL;
res->curBlock = block;
res->spaceLeft = 0; /* be sure it's marked full */
}
return space;
}
/* Otherwise, start a new block. */
block = (PGresult_data *) malloc(PGRESULT_DATA_BLOCKSIZE);
if (!block)
return NULL;
block->next = res->curBlock;
res->curBlock = block;
if (isBinary)
{
/* object needs full alignment */
res->curOffset = PGRESULT_BLOCK_OVERHEAD;
res->spaceLeft = PGRESULT_DATA_BLOCKSIZE - PGRESULT_BLOCK_OVERHEAD;
}
else
{
/* we can cram it right after the overhead pointer */
res->curOffset = sizeof(PGresult_data);
res->spaceLeft = PGRESULT_DATA_BLOCKSIZE - sizeof(PGresult_data);
}
space = block->space + res->curOffset;
res->curOffset += nBytes;
res->spaceLeft -= nBytes;
return space;
}
/*
* pqResultStrdup -
* Like strdup, but the space is subsidiary PGresult space.
*/
char *
pqResultStrdup(PGresult *res, const char *str)
{
char *space = (char *) pqResultAlloc(res, strlen(str) + 1, FALSE);
if (space)
strcpy(space, str);
return space;
}
/*
* pqSetResultError -
* assign a new error message to a PGresult
*/
void
pqSetResultError(PGresult *res, const char *msg)
{
if (!res)
return;
if (msg && *msg)
res->errMsg = pqResultStrdup(res, msg);
else
res->errMsg = NULL;
}
/*
* pqCatenateResultError -
* concatenate a new error message to the one already in a PGresult
*/
static void
pqCatenateResultError(PGresult *res, const char *msg)
{
PQExpBufferData errorBuf;
if (!res || !msg)
return;
initPQExpBuffer(&errorBuf);
if (res->errMsg)
appendPQExpBufferStr(&errorBuf, res->errMsg);
appendPQExpBufferStr(&errorBuf, msg);
pqSetResultError(res, errorBuf.data);
termPQExpBuffer(&errorBuf);
}
/*
* PQclear -
* free's the memory associated with a PGresult
*/
void
PQclear(PGresult *res)
{
PGresult_data *block;
if (!res)
return;
/* Free all the subsidiary blocks */
while ((block = res->curBlock) != NULL)
{
res->curBlock = block->next;
free(block);
}
/* Free the top-level tuple pointer array */
if (res->tuples)
free(res->tuples);
/* Free the PGresult structure itself */
free(res);
}
/*
* Handy subroutine to deallocate any partially constructed async result.
*/
void
pqClearAsyncResult(PGconn *conn)
{
if (conn->result)
PQclear(conn->result);
conn->result = NULL;
conn->curTuple = NULL;
}
/*
* This subroutine deletes any existing async result, sets conn->result
* to a PGresult with status PGRES_FATAL_ERROR, and stores the current
* contents of conn->errorMessage into that result. It differs from a
* plain call on PQmakeEmptyPGresult() in that if there is already an
* async result with status PGRES_FATAL_ERROR, the current error message
* is APPENDED to the old error message instead of replacing it. This
* behavior lets us report multiple error conditions properly, if necessary.
* (An example where this is needed is when the backend sends an 'E' message
* and immediately closes the connection --- we want to report both the
* backend error and the connection closure error.)
*/
static void
saveErrorResult(PGconn *conn)
{
/*
* If no old async result, just let PQmakeEmptyPGresult make one.
* Likewise if old result is not an error message.
*/
if (conn->result == NULL ||
conn->result->resultStatus != PGRES_FATAL_ERROR ||
conn->result->errMsg == NULL)
{
pqClearAsyncResult(conn);
conn->result = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
}
else
{
/* Else, concatenate error message to existing async result. */
pqCatenateResultError(conn->result, conn->errorMessage.data);
}
}
/*
* This subroutine prepares an async result object for return to the caller.
* If there is not already an async result object, build an error object
* using whatever is in conn->errorMessage. In any case, clear the async
* result storage and make sure PQerrorMessage will agree with the result's
* error string.
*/
static PGresult *
prepareAsyncResult(PGconn *conn)
{
PGresult *res;
/*
* conn->result is the PGresult to return. If it is NULL (which
* probably shouldn't happen) we assume there is an appropriate error
* message in conn->errorMessage.
*/
res = conn->result;
conn->result = NULL; /* handing over ownership to caller */
conn->curTuple = NULL; /* just in case */
if (!res)
res = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
else
{
/*
* Make sure PQerrorMessage agrees with result; it could be
* different if we have concatenated messages.
*/
resetPQExpBuffer(&conn->errorMessage);
appendPQExpBufferStr(&conn->errorMessage,
PQresultErrorMessage(res));
}
return res;
}
/*
* addTuple
* add a row pointer to the PGresult structure, growing it if necessary
* Returns TRUE if OK, FALSE if not enough memory to add the row
*/
static int
addTuple(PGresult *res, PGresAttValue * tup)
{
if (res->ntups >= res->tupArrSize)
{
/*
* Try to grow the array.
*
* We can use realloc because shallow copying of the structure is
* okay. Note that the first time through, res->tuples is NULL.
* While ANSI says that realloc() should act like malloc() in that
* case, some old C libraries (like SunOS 4.1.x) coredump instead.
* On failure realloc is supposed to return NULL without damaging
* the existing allocation. Note that the positions beyond
* res->ntups are garbage, not necessarily NULL.
*/
int newSize = (res->tupArrSize > 0) ? res->tupArrSize * 2 : 128;
PGresAttValue **newTuples;
if (res->tuples == NULL)
newTuples = (PGresAttValue **)
malloc(newSize * sizeof(PGresAttValue *));
else
newTuples = (PGresAttValue **)
realloc(res->tuples, newSize * sizeof(PGresAttValue *));
if (!newTuples)
return FALSE; /* malloc or realloc failed */
res->tupArrSize = newSize;
res->tuples = newTuples;
}
res->tuples[res->ntups] = tup;
res->ntups++;
return TRUE;
}
/*
* PQsendQuery
* Submit a query, but don't wait for it to finish
*
* Returns: 1 if successfully submitted
* 0 if error (conn->errorMessage is set)
*/
int
PQsendQuery(PGconn *conn, const char *query)
{
if (!conn)
return 0;
/* clear the error string */
resetPQExpBuffer(&conn->errorMessage);
if (!query)
{
printfPQExpBuffer(&conn->errorMessage,
"PQsendQuery() -- query pointer is null.\n");
return 0;
}
/* Don't try to send if we know there's no live connection. */
if (conn->status != CONNECTION_OK)
{
printfPQExpBuffer(&conn->errorMessage,
"PQsendQuery() -- There is no connection "
"to the backend.\n");
return 0;
}
/* Can't send while already busy, either. */
if (conn->asyncStatus != PGASYNC_IDLE)
{
printfPQExpBuffer(&conn->errorMessage,
"PQsendQuery() -- another query already in progress.\n");
return 0;
}
/* initialize async result-accumulation state */
conn->result = NULL;
conn->curTuple = NULL;
/* send the query to the backend; */
/*
* in order to guarantee that we don't send a partial query where we
* would become out of sync with the backend and/or block during a
* non-blocking connection we must first flush the send buffer before
* sending more data
*
* an alternative is to implement 'queue reservations' where we are able
* to roll up a transaction (the 'Q' along with our query) and make
* sure we have enough space for it all in the send buffer.
*/
if (pqIsnonblocking(conn))
{
/*
* the buffer must have emptied completely before we allow a new
* query to be buffered
*/
if (pqFlush(conn))
return 0;
/* 'Q' == queries */
/* XXX: if we fail here we really ought to not block */
if (pqPutnchar("Q", 1, conn) ||
pqPuts(query, conn))
{
handleSendFailure(conn);
return 0;
}
/*
* give the data a push, ignore the return value as ConsumeInput()
* will do any aditional flushing if needed
*/
(void) pqFlush(conn);
}
else
{
/*
* the frontend-backend protocol uses 'Q' to designate queries
*/
if (pqPutnchar("Q", 1, conn) ||
pqPuts(query, conn) ||
pqFlush(conn))
{
handleSendFailure(conn);
return 0;
}
}
/* OK, it's launched! */
conn->asyncStatus = PGASYNC_BUSY;
return 1;
}
/*
* handleSendFailure: try to clean up after failure to send command.
*
* Primarily, what we want to accomplish here is to process an async
* NOTICE message that the backend might have sent just before it died.
*
* NOTE: this routine should only be called in PGASYNC_IDLE state.
*/
static void
handleSendFailure(PGconn *conn)
{
/*
* Accept any available input data, ignoring errors. Note that if
* pqReadData decides the backend has closed the channel, it will
* close our side of the socket --- that's just what we want here.
*/
while (pqReadData(conn) > 0)
/* loop until no more data readable */ ;
/*
* Parse any available input messages. Since we are in PGASYNC_IDLE
* state, only NOTICE and NOTIFY messages will be eaten.
*/
parseInput(conn);
}
/*
* Consume any available input from the backend
* 0 return: some kind of trouble
* 1 return: no problem
*/
int
PQconsumeInput(PGconn *conn)
{
if (!conn)
return 0;
/*
* Load more data, if available. We do this no matter what state we
* are in, since we are probably getting called because the
* application wants to get rid of a read-select condition. Note that
* we will NOT block waiting for more input.
*/
if (pqReadData(conn) < 0)
{
/*
* for non-blocking connections try to flush the send-queue
* otherwise we may never get a responce for something that may
* not have already been sent because it's in our write buffer!
*/
if (pqIsnonblocking(conn))
(void) pqFlush(conn);
return 0;
}
/* Parsing of the data waits till later. */
return 1;
}
/*
* 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.
*/
static void
parseInput(PGconn *conn)
{
char id;
char noticeWorkspace[128];
/*
* Loop to parse successive complete messages available in the buffer.
*/
for (;;)
{
/*
* Quit if in COPY_OUT state: we expect raw data from the server
* until PQendcopy is called. Don't try to parse it according to
* the normal protocol. (This is bogus. The data lines ought to
* be part of the protocol and have identifying leading
* characters.)
*/
if (conn->asyncStatus == PGASYNC_COPY_OUT)
return;
/*
* OK to try to read a message type code.
*/
conn->inCursor = conn->inStart;
if (pqGetc(&id, conn))
return;
/*
* NOTIFY and NOTICE messages can happen in any state besides COPY
* OUT; 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.
*/
if (id == 'A')
{
if (getNotify(conn))
return;
}
else if (id == 'N')
{
if (getNotice(conn))
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;
* 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 (getNotice(conn))
return;
}
else
{
sprintf(noticeWorkspace,
"Backend message type 0x%02x arrived while idle\n",
id);
DONOTICE(conn, noticeWorkspace);
/* Discard the unexpected message; good idea?? */
conn->inStart = conn->inEnd;
break;
}
}
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);
strncpy(conn->result->cmdStatus, conn->workBuffer.data,
CMDSTATUS_LEN);
conn->asyncStatus = PGASYNC_READY;
break;
case 'E': /* error return */
if (pqGets(&conn->errorMessage, conn))
return;
/* build an error result holding the error message */
saveErrorResult(conn);
conn->asyncStatus = PGASYNC_READY;
break;
case 'Z': /* backend is ready for new query */
conn->asyncStatus = PGASYNC_IDLE;
break;
case 'I': /* empty query */
/* read and throw away the closing '\0' */
if (pqGetc(&id, conn))
return;
if (id != '\0')
{
sprintf(noticeWorkspace,
"unexpected character %c following 'I'\n",
id);
DONOTICE(conn, noticeWorkspace);
}
if (conn->result == NULL)
conn->result = PQmakeEmptyPGresult(conn,
PGRES_EMPTY_QUERY);
conn->asyncStatus = PGASYNC_READY;
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 'P': /* synchronous (normal) portal */
if (pqGets(&conn->workBuffer, conn))
return;
/* We pretty much ignore this message type... */
break;
case 'T': /* row descriptions (start of query
* results) */
if (conn->result == NULL)
{
/* First 'T' in a query sequence */
if (getRowDescriptions(conn))
return;
}
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 'D': /* ASCII data tuple */
if (conn->result != NULL)
{
/* Read another tuple of a normal query response */
if (getAnotherTuple(conn, FALSE))
return;
}
else
{
sprintf(noticeWorkspace,
"Backend sent D message without prior T\n");
DONOTICE(conn, noticeWorkspace);
/* Discard the unexpected message; good idea?? */
conn->inStart = conn->inEnd;
return;
}
break;
case 'B': /* Binary data tuple */
if (conn->result != NULL)
{
/* Read another tuple of a normal query response */
if (getAnotherTuple(conn, TRUE))
return;
}
else
{
sprintf(noticeWorkspace,
"Backend sent B message without prior T\n");
DONOTICE(conn, noticeWorkspace);
/* Discard the unexpected message; good idea?? */
conn->inStart = conn->inEnd;
return;
}
break;
case 'G': /* Start Copy In */
conn->asyncStatus = PGASYNC_COPY_IN;
break;
case 'H': /* Start Copy Out */
conn->asyncStatus = PGASYNC_COPY_OUT;
break;
default:
printfPQExpBuffer(&conn->errorMessage,
"Unknown protocol character '%c' read from backend. "
"(The protocol character is the first character the "
"backend sends in response to a query it receives).\n",
id);
/* build an error result holding the error message */
saveErrorResult(conn);
/* Discard the unexpected message; good idea?? */
conn->inStart = conn->inEnd;
conn->asyncStatus = PGASYNC_READY;
return;
} /* switch on protocol character */
}
/* Successfully consumed this message */
conn->inStart = conn->inCursor;
}
}
/*
* parseInput subroutine to read a 'T' (row descriptions) message.
* We build a PGresult structure containing the attribute data.
* Returns: 0 if completed message, EOF if not enough data yet.
*
* Note that if we run out of data, we have to release the partially
* constructed PGresult, and rebuild it again next time. Fortunately,
* that shouldn't happen often, since 'T' messages usually fit in a packet.
*/
static int
getRowDescriptions(PGconn *conn)
{
PGresult *result;
int nfields;
int i;
result = PQmakeEmptyPGresult(conn, PGRES_TUPLES_OK);
/* parseInput already read the 'T' label. */
/* the next two bytes are the number of fields */
if (pqGetInt(&(result->numAttributes), 2, conn))
{
PQclear(result);
return EOF;
}
nfields = result->numAttributes;
/* allocate space for the attribute descriptors */
if (nfields > 0)
{
result->attDescs = (PGresAttDesc *)
pqResultAlloc(result, nfields * sizeof(PGresAttDesc), TRUE);
MemSet((char *) result->attDescs, 0, nfields * sizeof(PGresAttDesc));
}
/* get type info */
for (i = 0; i < nfields; i++)
{
int typid;
int typlen;
int atttypmod;
if (pqGets(&conn->workBuffer, conn) ||
pqGetInt(&typid, 4, conn) ||
pqGetInt(&typlen, 2, conn) ||
pqGetInt(&atttypmod, 4, conn))
{
PQclear(result);
return EOF;
}
/*
* Since pqGetInt treats 2-byte integers as unsigned, we need to
* coerce the special value "-1" to signed form. (-1 is sent for
* variable-length fields.) Formerly, libpq effectively did a
* sign-extension on the 2-byte value by storing it in a signed
* short. Now we only coerce the single value 65535 == -1; values
* 32768..65534 are taken as valid field lengths.
*/
if (typlen == 0xFFFF)
typlen = -1;
result->attDescs[i].name = pqResultStrdup(result,
conn->workBuffer.data);
result->attDescs[i].typid = typid;
result->attDescs[i].typlen = typlen;
result->attDescs[i].atttypmod = atttypmod;
}
/* Success! */
conn->result = result;
return 0;
}
/*
* parseInput subroutine to read a 'B' or 'D' (row data) message.
* We add another tuple to the existing PGresult structure.
* Returns: 0 if completed message, EOF if error or not enough data yet.
*
* Note that if we run out of data, we have to suspend and reprocess
* the message after more data is received. We keep a partially constructed
* tuple in conn->curTuple, and avoid reallocating already-allocated storage.
*/
static int
getAnotherTuple(PGconn *conn, int binary)
{
PGresult *result = conn->result;
int nfields = result->numAttributes;
PGresAttValue *tup;
/* the backend sends us a bitmap of which attributes are null */
char std_bitmap[64]; /* used unless it doesn't fit */
char *bitmap = std_bitmap;
int i;
size_t nbytes; /* the number of bytes in bitmap */
char bmap; /* One byte of the bitmap */
int bitmap_index; /* Its index */
int bitcnt; /* number of bits examined in current byte */
int vlen; /* length of the current field value */
result->binary = binary;
/* Allocate tuple space if first time for this data message */
if (conn->curTuple == NULL)
{
conn->curTuple = (PGresAttValue *)
pqResultAlloc(result, nfields * sizeof(PGresAttValue), TRUE);
if (conn->curTuple == NULL)
goto outOfMemory;
MemSet((char *) conn->curTuple, 0, nfields * sizeof(PGresAttValue));
}
tup = conn->curTuple;
/* Get the null-value bitmap */
nbytes = (nfields + BYTELEN - 1) / BYTELEN;
/* malloc() only for unusually large field counts... */
if (nbytes > sizeof(std_bitmap))
bitmap = (char *) malloc(nbytes);
if (pqGetnchar(bitmap, nbytes, conn))
goto EOFexit;
/* Scan the fields */
bitmap_index = 0;
bmap = bitmap[bitmap_index];
bitcnt = 0;
for (i = 0; i < nfields; i++)
{
if (!(bmap & 0200))
{
/* if the field value is absent, make it a null string */
tup[i].value = result->null_field;
tup[i].len = NULL_LEN;
}
else
{
/* get the value length (the first four bytes are for length) */
if (pqGetInt(&vlen, 4, conn))
goto EOFexit;
if (binary == 0)
vlen = vlen - 4;
if (vlen < 0)
vlen = 0;
if (tup[i].value == NULL)
{
tup[i].value = (char *) pqResultAlloc(result, vlen + 1, binary);
if (tup[i].value == NULL)
goto outOfMemory;
}
tup[i].len = vlen;
/* read in the value */
if (vlen > 0)
if (pqGetnchar((char *) (tup[i].value), vlen, conn))
goto EOFexit;
/* we have to terminate this ourselves */
tup[i].value[vlen] = '\0';
}
/* advance the bitmap stuff */
bitcnt++;
if (bitcnt == BYTELEN)
{
bitmap_index++;
bmap = bitmap[bitmap_index];
bitcnt = 0;
}
else
bmap <<= 1;
}
/* Success! Store the completed tuple in the result */
if (!addTuple(result, tup))
goto outOfMemory;
/* and reset for a new message */
conn->curTuple = NULL;
if (bitmap != std_bitmap)
free(bitmap);
return 0;
outOfMemory:
/* Replace partially constructed result with an error result */
/*
* we do NOT use saveErrorResult() here, because of the likelihood
* that there's not enough memory to concatenate messages...
*/
pqClearAsyncResult(conn);
printfPQExpBuffer(&conn->errorMessage,
"getAnotherTuple() -- out of memory for result\n");
conn->result = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
conn->asyncStatus = PGASYNC_READY;
/* Discard the failed message --- good idea? */
conn->inStart = conn->inEnd;
EOFexit:
if (bitmap != std_bitmap)
free(bitmap);
return EOF;
}
/*
* PQisBusy
* Return TRUE if PQgetResult would block waiting for input.
*/
int
PQisBusy(PGconn *conn)
{
if (!conn)
return FALSE;
/* Parse any available data, if our state permits. */
parseInput(conn);
/* PQgetResult will return immediately in all states except BUSY. */
return conn->asyncStatus == PGASYNC_BUSY;
}
/*
* PQgetResult
* Get the next PGresult produced by a query.
* Returns NULL if and only if no query work remains.
*/
PGresult *
PQgetResult(PGconn *conn)
{
PGresult *res;
if (!conn)
return NULL;
/* Parse any available data, if our state permits. */
parseInput(conn);
/* If not ready to return something, block until we are. */
while (conn->asyncStatus == PGASYNC_BUSY)
{
/* Wait for some more data, and load it. */
if (pqWait(TRUE, FALSE, conn) ||
pqReadData(conn) < 0)
{
/*
* conn->errorMessage has been set by pqWait or pqReadData. We
* want to append it to any already-received error message.
*/
saveErrorResult(conn);
conn->asyncStatus = PGASYNC_IDLE;
return prepareAsyncResult(conn);
}
/* Parse it. */
parseInput(conn);
}
/* Return the appropriate thing. */
switch (conn->asyncStatus)
{
case PGASYNC_IDLE:
res = NULL; /* query is complete */
break;
case PGASYNC_READY:
res = prepareAsyncResult(conn);
/* Set the state back to BUSY, allowing parsing to proceed. */
conn->asyncStatus = PGASYNC_BUSY;
break;
case PGASYNC_COPY_IN:
res = PQmakeEmptyPGresult(conn, PGRES_COPY_IN);
break;
case PGASYNC_COPY_OUT:
res = PQmakeEmptyPGresult(conn, PGRES_COPY_OUT);
break;
default:
printfPQExpBuffer(&conn->errorMessage,
"PQgetResult: Unexpected asyncStatus %d\n",
(int) conn->asyncStatus);
res = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
break;
}
return res;
}
/*
* PQexec
* send a query to the backend and package up the result in a PGresult
*
* If the query was not even sent, return NULL; conn->errorMessage is set to
* a relevant message.
* If the query was sent, a new PGresult is returned (which could indicate
* either success or failure).
* The user is responsible for freeing the PGresult via PQclear()
* when done with it.
*/
PGresult *
PQexec(PGconn *conn, const char *query)
{
PGresult *result;
PGresult *lastResult;
bool savedblocking;
/*
* we assume anyone calling PQexec wants blocking behaviour, we force
* the blocking status of the connection to blocking for the duration
* of this function and restore it on return
*/
savedblocking = pqIsnonblocking(conn);
if (PQsetnonblocking(conn, FALSE) == -1)
return NULL;
/*
* Silently discard any prior query result that application didn't
* eat. This is probably poor design, but it's here for backward
* compatibility.
*/
while ((result = PQgetResult(conn)) != NULL)
{
if (result->resultStatus == PGRES_COPY_IN ||
result->resultStatus == PGRES_COPY_OUT)
{
PQclear(result);
printfPQExpBuffer(&conn->errorMessage,
"PQexec: you gotta get out of a COPY state yourself.\n");
/* restore blocking status */
goto errout;
}
PQclear(result);
}
/* OK to send the message */
if (!PQsendQuery(conn, query))
goto errout; /* restore blocking status */
/*
* For backwards compatibility, return the last result if there are
* more than one --- but merge error messages if we get more than one
* error result.
*
* We have to stop if we see copy in/out, however. We will resume parsing
* when application calls PQendcopy.
*/
lastResult = NULL;
while ((result = PQgetResult(conn)) != NULL)
{
if (lastResult)
{
if (lastResult->resultStatus == PGRES_FATAL_ERROR &&
result->resultStatus == PGRES_FATAL_ERROR)
{
pqCatenateResultError(lastResult, result->errMsg);
PQclear(result);
result = lastResult;
/* Make sure PQerrorMessage agrees with catenated result */
resetPQExpBuffer(&conn->errorMessage);
appendPQExpBufferStr(&conn->errorMessage, result->errMsg);
}
else
PQclear(lastResult);
}
lastResult = result;
if (result->resultStatus == PGRES_COPY_IN ||
result->resultStatus == PGRES_COPY_OUT)
break;
}
if (PQsetnonblocking(conn, savedblocking) == -1)
return NULL;
return lastResult;
errout:
if (PQsetnonblocking(conn, savedblocking) == -1)
return NULL;
return NULL;
}
/*
* Attempt to read a Notice response message.
* This is possible in several places, so we break it out as a subroutine.
* Entry: 'N' flag character has already been consumed.
* Exit: returns 0 if successfully consumed Notice message.
* returns EOF if not enough data.
*/
static int
getNotice(PGconn *conn)
{
/*
* Since the Notice might be pretty long, we create a temporary
* PQExpBuffer rather than using conn->workBuffer. workBuffer is
* intended for stuff that is expected to be short.
*/
PQExpBufferData noticeBuf;
initPQExpBuffer(&noticeBuf);
if (pqGets(&noticeBuf, conn))
{
termPQExpBuffer(&noticeBuf);
return EOF;
}
DONOTICE(conn, noticeBuf.data);
termPQExpBuffer(&noticeBuf);
return 0;
}
/*
* Attempt to read a Notify response message.
* This is possible in several places, so we break it out as a subroutine.
* Entry: 'A' flag character has already been consumed.
* Exit: returns 0 if successfully consumed Notify message.
* returns EOF if not enough data.
*/
static int
getNotify(PGconn *conn)
{
int be_pid;
PGnotify *newNotify;
if (pqGetInt(&be_pid, 4, conn))
return EOF;
if (pqGets(&conn->workBuffer, conn))
return EOF;
newNotify = (PGnotify *) malloc(sizeof(PGnotify));
strncpy(newNotify->relname, conn->workBuffer.data, NAMEDATALEN);
newNotify->be_pid = be_pid;
DLAddTail(conn->notifyList, DLNewElem(newNotify));
return 0;
}
/*
* PQnotifies
* returns a PGnotify* structure of the latest async notification
* that has not yet been handled
*
* returns NULL, if there is currently
* no unhandled async notification from the backend
*
* the CALLER is responsible for FREE'ing the structure returned
*/
PGnotify *
PQnotifies(PGconn *conn)
{
Dlelem *e;
PGnotify *event;
if (!conn)
return NULL;
/* Parse any available data to see if we can extract NOTIFY messages. */
parseInput(conn);
/* RemHead returns NULL if list is empty */
e = DLRemHead(conn->notifyList);
if (!e)
return NULL;
event = (PGnotify *) DLE_VAL(e);
DLFreeElem(e);
return event;
}
/*
* PQgetline - gets a newline-terminated string from the backend.
*
* Chiefly here so that applications can use "COPY <rel> to stdout"
* and read the output string. Returns a null-terminated string in s.
*
* PQgetline reads up to maxlen-1 characters (like fgets(3)) but strips
* the terminating \n (like gets(3)).
*
* CAUTION: the caller is responsible for detecting the end-of-copy signal
* (a line containing just "\.") when using this routine.
*
* RETURNS:
* EOF if it is detected or invalid arguments are given
* 0 if EOL is reached (i.e., \n has been read)
* (this is required for backward-compatibility -- this
* routine used to always return EOF or 0, assuming that
* the line ended within maxlen bytes.)
* 1 in other cases (i.e., the buffer was filled before \n is reached)
*/
int
PQgetline(PGconn *conn, char *s, int maxlen)
{
int result = 1; /* return value if buffer overflows */
if (!s || maxlen <= 0)
return EOF;
if (!conn || conn->sock < 0)
{
*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;
}
/*
* PQgetlineAsync - gets a newline-terminated string without blocking.
*
* This routine is for applications that want to do "COPY <rel> to stdout"
* asynchronously, that is without blocking. Having issued the COPY command
* and gotten a PGRES_COPY_OUT response, the app should call PQconsumeInput
* and this routine until the end-of-data signal is detected. Unlike
* PQgetline, this routine takes responsibility for detecting end-of-data.
*
* On each call, PQgetlineAsync will return data if a complete newline-
* terminated data line is available in libpq's input buffer, or if the
* incoming data line is too long to fit in the buffer offered by the caller.
* Otherwise, no data is returned until the rest of the line arrives.
*
* If -1 is returned, the end-of-data signal has been recognized (and removed
* from libpq's input buffer). The caller *must* next call PQendcopy and
* then return to normal processing.
*
* RETURNS:
* -1 if the end-of-copy-data marker has been recognized
* 0 if no data is available
* >0 the number of bytes returned.
* The data returned will not extend beyond a newline character. If possible
* a whole line will be returned at one time. But if the buffer offered by
* the caller is too small to hold a line sent by the backend, then a partial
* data line will be returned. This can be detected by testing whether the
* last returned byte is '\n' or not.
* The returned string is *not* null-terminated.
*/
int
PQgetlineAsync(PGconn *conn, char *buffer, int bufsize)
{
int avail;
if (!conn || conn->asyncStatus != PGASYNC_COPY_OUT)
return -1; /* we are not doing a copy... */
/*
* Move data from libpq's buffer to the caller's. We want to accept
* data only in units of whole lines, not partial lines. This ensures
* that we can recognize the terminator line "\\.\n". (Otherwise, if
* it happened to cross a packet/buffer boundary, we might hand the
* first one or two characters off to the caller, which we shouldn't.)
*/
conn->inCursor = conn->inStart;
avail = bufsize;
while (avail > 0 && conn->inCursor < conn->inEnd)
{
char c = conn->inBuffer[conn->inCursor++];
*buffer++ = c;
--avail;
if (c == '\n')
{
/* Got a complete line; mark the data removed from libpq */
conn->inStart = conn->inCursor;
/* Is it the endmarker line? */
if (bufsize - avail == 3 && buffer[-3] == '\\' && buffer[-2] == '.')
return -1;
/* No, return the data line to the caller */
return bufsize - avail;
}
}
/*
* We don't have a complete line. We'd prefer to leave it in libpq's
* buffer until the rest arrives, but there is a special case: what if
* the line is longer than the buffer the caller is offering us? In
* that case we'd better hand over a partial line, else we'd get into
* an infinite loop. Do this in a way that ensures we can't
* misrecognize a terminator line later: leave last 3 characters in
* libpq buffer.
*/
if (avail == 0 && bufsize > 3)
{
conn->inStart = conn->inCursor - 3;
return bufsize - 3;
}
return 0;
}
/*
* PQputline -- sends a string to the backend.
* Returns 0 if OK, EOF if not.
*
* Chiefly here so that applications can use "COPY <rel> from stdin".
*/
int
PQputline(PGconn *conn, const char *s)
{
if (!conn || conn->sock < 0)
return EOF;
return pqPutnchar(s, strlen(s), conn);
}
/*
* PQputnbytes -- like PQputline, but buffer need not be null-terminated.
* Returns 0 if OK, EOF if not.
*/
int
PQputnbytes(PGconn *conn, const char *buffer, int nbytes)
{
if (!conn || conn->sock < 0)
return EOF;
return pqPutnchar(buffer, nbytes, conn);
}
/*
* PQendcopy
* After completing the data transfer portion of a copy in/out,
* the application must call this routine to finish the command protocol.
*
* RETURNS:
* 0 on success
* 1 on failure
*/
int
PQendcopy(PGconn *conn)
{
PGresult *result;
if (!conn)
return 0;
if (conn->asyncStatus != PGASYNC_COPY_IN &&
conn->asyncStatus != PGASYNC_COPY_OUT)
{
printfPQExpBuffer(&conn->errorMessage,
"PQendcopy() -- I don't think there's a copy in progress.\n");
return 1;
}
/*
* make sure no data is waiting to be sent, abort if we are
* non-blocking and the flush fails
*/
if (pqFlush(conn) && pqIsnonblocking(conn))
return (1);
/* non blocking connections may have to abort at this point. */
if (pqIsnonblocking(conn) && PQisBusy(conn))
return (1);
/* Return to active duty */
conn->asyncStatus = PGASYNC_BUSY;
resetPQExpBuffer(&conn->errorMessage);
/* Wait for the completion response */
result = PQgetResult(conn);
/* Expecting a successful result */
if (result && result->resultStatus == PGRES_COMMAND_OK)
{
PQclear(result);
return 0;
}
/*
* Trouble. The worst case is that we've lost sync with the backend
* entirely due to application screwup of the copy in/out protocol. To
* recover, reset the connection (talk about using a sledgehammer...)
*/
PQclear(result);
if (conn->errorMessage.len > 0)
DONOTICE(conn, conn->errorMessage.data);
DONOTICE(conn, "PQendcopy: resetting connection\n");
/*
* Users doing non-blocking connections need to handle the reset
* themselves, they'll need to check the connection status if we
* return an error.
*/
if (pqIsnonblocking(conn))
PQresetStart(conn);
else
PQreset(conn);
return 1;
}
/* ----------------
* PQfn - Send a function call to the POSTGRES backend.
*
* conn : backend connection
* fnid : function id
* result_buf : pointer to result buffer (&int if integer)
* result_len : length of return value.
* actual_result_len: actual length returned. (differs from result_len
* for varlena structures.)
* result_type : If the result is an integer, this must be 1,
* otherwise this should be 0
* args : pointer to an array of function arguments.
* (each has length, if integer, and value/pointer)
* nargs : # of arguments in args array.
*
* RETURNS
* PGresult with status = PGRES_COMMAND_OK if successful.
* *actual_result_len is > 0 if there is a return value, 0 if not.
* PGresult with status = PGRES_FATAL_ERROR if backend returns an error.
* NULL on communications failure. conn->errorMessage will be set.
* ----------------
*/
PGresult *
PQfn(PGconn *conn,
int 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;
*actual_result_len = 0;
if (!conn)
return NULL;
/* clear the error string */
resetPQExpBuffer(&conn->errorMessage);
if (conn->sock < 0 || conn->asyncStatus != PGASYNC_IDLE ||
conn->result != NULL)
{
printfPQExpBuffer(&conn->errorMessage,
"PQfn() -- connection in wrong state\n");
return NULL;
}
if (pqPuts("F ", conn) || /* function */
pqPutInt(fnid, 4, conn) || /* function id */
pqPutInt(nargs, 4, conn)) /* # of args */
{
handleSendFailure(conn);
return NULL;
}
for (i = 0; i < nargs; ++i)
{ /* len.int4 + contents */
if (pqPutInt(args[i].len, 4, conn))
{
handleSendFailure(conn);
return NULL;
}
if (args[i].isint)
{
if (pqPutInt(args[i].u.integer, 4, conn))
{
handleSendFailure(conn);
return NULL;
}
}
else
{
if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
{
handleSendFailure(conn);
return NULL;
}
}
}
if (pqFlush(conn))
{
handleSendFailure(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,
"FATAL: PQfn: protocol error: id=0x%x\n",
id);
saveErrorResult(conn);
conn->inStart = conn->inCursor;
return prepareAsyncResult(conn);
}
break;
case 'E': /* error return */
if (pqGets(&conn->errorMessage, conn))
continue;
/* build an error result holding the error message */
saveErrorResult(conn);
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 (getNotice(conn))
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 prepareAsyncResult(conn);
return PQmakeEmptyPGresult(conn, status);
default:
/* The backend violates the protocol. */
printfPQExpBuffer(&conn->errorMessage,
"FATAL: PQfn: protocol error: id=0x%x\n",
id);
saveErrorResult(conn);
conn->inStart = conn->inCursor;
return prepareAsyncResult(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.
*/
saveErrorResult(conn);
return prepareAsyncResult(conn);
}
/* ====== accessor funcs for PGresult ======== */
ExecStatusType
PQresultStatus(const PGresult *res)
{
if (!res)
return PGRES_NONFATAL_ERROR;
return res->resultStatus;
}
char *
PQresStatus(ExecStatusType status)
{
if (status < 0 || status >= sizeof pgresStatus / sizeof pgresStatus[0])
return "Invalid ExecStatusType code";
return pgresStatus[status];
}
char *
PQresultErrorMessage(const PGresult *res)
{
if (!res || !res->errMsg)
return "";
return res->errMsg;
}
int
PQntuples(const PGresult *res)
{
if (!res)
return 0;
return res->ntups;
}
int
PQnfields(const PGresult *res)
{
if (!res)
return 0;
return res->numAttributes;
}
int
PQbinaryTuples(const PGresult *res)
{
if (!res)
return 0;
return res->binary;
}
/*
* Helper routines to range-check field numbers and tuple numbers.
* Return TRUE if OK, FALSE if not
*/
static int
check_field_number(const char *routineName, const PGresult *res, int field_num)
{
char noticeBuf[128];
if (!res)
return FALSE; /* no way to display error message... */
if (field_num < 0 || field_num >= res->numAttributes)
{
if (res->noticeHook)
{
sprintf(noticeBuf,
"%s: ERROR! field number %d is out of range 0..%d\n",
routineName, field_num, res->numAttributes - 1);
DONOTICE(res, noticeBuf);
}
return FALSE;
}
return TRUE;
}
static int
check_tuple_field_number(const char *routineName, const PGresult *res,
int tup_num, int field_num)
{
char noticeBuf[128];
if (!res)
return FALSE; /* no way to display error message... */
if (tup_num < 0 || tup_num >= res->ntups)
{
if (res->noticeHook)
{
sprintf(noticeBuf,
"%s: ERROR! tuple number %d is out of range 0..%d\n",
routineName, tup_num, res->ntups - 1);
DONOTICE(res, noticeBuf);
}
return FALSE;
}
if (field_num < 0 || field_num >= res->numAttributes)
{
if (res->noticeHook)
{
sprintf(noticeBuf,
"%s: ERROR! field number %d is out of range 0..%d\n",
routineName, field_num, res->numAttributes - 1);
DONOTICE(res, noticeBuf);
}
return FALSE;
}
return TRUE;
}
/*
returns NULL if the field_num is invalid
*/
char *
PQfname(const PGresult *res, int field_num)
{
if (!check_field_number("PQfname", res, field_num))
return NULL;
if (res->attDescs)
return res->attDescs[field_num].name;
else
return NULL;
}
/*
returns -1 on a bad field name
*/
int
PQfnumber(const PGresult *res, const char *field_name)
{
int i;
char *field_case;
if (!res)
return -1;
if (field_name == NULL ||
field_name[0] == '\0' ||
res->attDescs == NULL)
return -1;
field_case = strdup(field_name);
if (*field_case == '"')
{
strcpy(field_case, field_case + 1);
*(field_case + strlen(field_case) - 1) = '\0';
}
else
for (i = 0; field_case[i]; i++)
if (isascii((int) field_case[i]) &&
isupper((int) field_case[i]))
field_case[i] = tolower(field_case[i]);
for (i = 0; i < res->numAttributes; i++)
{
if (strcmp(field_case, res->attDescs[i].name) == 0)
{
free(field_case);
return i;
}
}
free(field_case);
return -1;
}
Oid
PQftype(const PGresult *res, int field_num)
{
if (!check_field_number("PQftype", res, field_num))
return InvalidOid;
if (res->attDescs)
return res->attDescs[field_num].typid;
else
return InvalidOid;
}
int
PQfsize(const PGresult *res, int field_num)
{
if (!check_field_number("PQfsize", res, field_num))
return 0;
if (res->attDescs)
return res->attDescs[field_num].typlen;
else
return 0;
}
int
PQfmod(const PGresult *res, int field_num)
{
if (!check_field_number("PQfmod", res, field_num))
return 0;
if (res->attDescs)
return res->attDescs[field_num].atttypmod;
else
return 0;
}
char *
PQcmdStatus(PGresult *res)
{
if (!res)
return NULL;
return res->cmdStatus;
}
/*
PQoidStatus -
if the last command was an INSERT, return the oid string
if not, return ""
*/
char *
PQoidStatus(const PGresult *res)
{
/*
* This must be enough to hold the result. Don't laugh, this is better
* than what this function used to do.
*/
static char buf[24];
size_t len;
if (!res || !res->cmdStatus || strncmp(res->cmdStatus, "INSERT ", 7) != 0)
return "";
len = strspn(res->cmdStatus + 7, "0123456789");
if (len > 23)
len = 23;
strncpy(buf, res->cmdStatus + 7, len);
buf[23] = '\0';
return buf;
}
/*
PQoidValue -
a perhaps preferable form of the above which just returns
an Oid type
*/
Oid
PQoidValue(const PGresult *res)
{
char *endptr = NULL;
long int result;
if (!res || !res->cmdStatus || strncmp(res->cmdStatus, "INSERT ", 7) != 0)
return InvalidOid;
errno = 0;
result = strtoul(res->cmdStatus + 7, &endptr, 10);
if (!endptr || (*endptr != ' ' && *endptr != '\0') || errno == ERANGE)
return InvalidOid;
else
return (Oid) result;
}
/*
PQcmdTuples -
if the last command was an INSERT/UPDATE/DELETE, return number
of inserted/affected tuples, if not, return ""
*/
char *
PQcmdTuples(PGresult *res)
{
char noticeBuf[128];
if (!res)
return "";
if (strncmp(res->cmdStatus, "INSERT", 6) == 0 ||
strncmp(res->cmdStatus, "DELETE", 6) == 0 ||
strncmp(res->cmdStatus, "UPDATE", 6) == 0)
{
char *p = res->cmdStatus + 6;
if (*p == 0)
{
if (res->noticeHook)
{
sprintf(noticeBuf,
"PQcmdTuples (%s) -- bad input from server\n",
res->cmdStatus);
DONOTICE(res, noticeBuf);
}
return "";
}
p++;
if (*(res->cmdStatus) != 'I') /* UPDATE/DELETE */
return p;
while (*p != ' ' && *p)
p++; /* INSERT: skip oid */
if (*p == 0)
{
if (res->noticeHook)
{
sprintf(noticeBuf,
"PQcmdTuples (INSERT) -- there's no # of tuples\n");
DONOTICE(res, noticeBuf);
}
return "";
}
p++;
return p;
}
return "";
}
/*
PQgetvalue:
return the value of field 'field_num' of row 'tup_num'
If res is binary, then the value returned is NOT a null-terminated
ASCII string, but the binary representation in the server's native
format.
if res is not binary, a null-terminated ASCII string is returned.
*/
char *
PQgetvalue(const PGresult *res, int tup_num, int field_num)
{
if (!check_tuple_field_number("PQgetvalue", res, tup_num, field_num))
return NULL;
return res->tuples[tup_num][field_num].value;
}
/* PQgetlength:
returns the length of a field value in bytes. If res is binary,
i.e. a result of a binary portal, then the length returned does
NOT include the size field of the varlena. (The data returned
by PQgetvalue doesn't either.)
*/
int
PQgetlength(const PGresult *res, int tup_num, int field_num)
{
if (!check_tuple_field_number("PQgetlength", res, tup_num, field_num))
return 0;
if (res->tuples[tup_num][field_num].len != NULL_LEN)
return res->tuples[tup_num][field_num].len;
else
return 0;
}
/* PQgetisnull:
returns the null status of a field value.
*/
int
PQgetisnull(const PGresult *res, int tup_num, int field_num)
{
if (!check_tuple_field_number("PQgetisnull", res, tup_num, field_num))
return 1; /* pretend it is null */
if (res->tuples[tup_num][field_num].len == NULL_LEN)
return 1;
else
return 0;
}
/* PQsetnonblocking:
sets the PGconn's database connection non-blocking if the arg is TRUE
or makes it non-blocking if the arg is FALSE, this will not protect
you from PQexec(), you'll only be safe when using the non-blocking
API
Needs to be called only on a connected database connection.
*/
int
PQsetnonblocking(PGconn *conn, int arg)
{
arg = (arg == TRUE) ? 1 : 0;
/* early out if the socket is already in the state requested */
if (arg == conn->nonblocking)
return (0);
/*
* to guarantee constancy for flushing/query/result-polling behavior
* we need to flush the send queue at this point in order to guarantee
* proper behavior. this is ok because either they are making a
* transition _from_ or _to_ blocking mode, either way we can block
* them.
*/
/* if we are going from blocking to non-blocking flush here */
if (pqFlush(conn))
return (-1);
conn->nonblocking = arg;
return (0);
}
/* return the blocking status of the database connection, TRUE == nonblocking,
FALSE == blocking
*/
int
PQisnonblocking(const PGconn *conn)
{
return (pqIsnonblocking(conn));
}
/* try to force data out, really only useful for non-blocking users */
int
PQflush(PGconn *conn)
{
return (pqFlush(conn));
}
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