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Sourcecode: postgresql-8.4 version File versions

fe-exec.c

/*-------------------------------------------------------------------------
 *
 * fe-exec.c
 *      functions related to sending a query down to the backend
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.203 2009/06/11 14:49:13 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include <ctype.h>
#include <fcntl.h>

#include "libpq-fe.h"
#include "libpq-int.h"

#include "mb/pg_wchar.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"
};

/*
 * static state needed by PQescapeString and PQescapeBytea; initialize to
 * values that result in backward-compatible behavior
 */
static int  static_client_encoding = PG_SQL_ASCII;
static bool static_std_strings = false;


static PGEvent *dupEvents(PGEvent *events, int count);
static bool PQsendQueryStart(PGconn *conn);
static int PQsendQueryGuts(PGconn *conn,
                        const char *command,
                        const char *stmtName,
                        int nParams,
                        const Oid *paramTypes,
                        const char *const * paramValues,
                        const int *paramLengths,
                        const int *paramFormats,
                        int resultFormat);
static void parseInput(PGconn *conn);
static bool PQexecStart(PGconn *conn);
static PGresult *PQexecFinish(PGconn *conn);
static int PQsendDescribe(PGconn *conn, char desc_type,
                     const char *desc_target);
static int  check_field_number(const PGresult *res, int field_num);


/* ----------------
 * 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.
 * ----------------
 */

#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.  Also, any PGEvents are copied from the conn.
 */
PGresult *
PQmakeEmptyPGresult(PGconn *conn, ExecStatusType status)
{
      PGresult   *result;

      result = (PGresult *) malloc(sizeof(PGresult));
      if (!result)
            return NULL;

      result->ntups = 0;
      result->numAttributes = 0;
      result->attDescs = NULL;
      result->tuples = NULL;
      result->tupArrSize = 0;
      result->numParameters = 0;
      result->paramDescs = NULL;
      result->resultStatus = status;
      result->cmdStatus[0] = '\0';
      result->binary = 0;
      result->events = NULL;
      result->nEvents = 0;
      result->errMsg = NULL;
      result->errFields = 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->noticeHooks = conn->noticeHooks;
            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;
            }

            /* copy events last; result must be valid if we need to PQclear */
            if (conn->nEvents > 0)
            {
                  result->events = dupEvents(conn->events, conn->nEvents);
                  if (!result->events)
                  {
                        PQclear(result);
                        return NULL;
                  }
                  result->nEvents = conn->nEvents;
            }
      }
      else
      {
            /* defaults... */
            result->noticeHooks.noticeRec = NULL;
            result->noticeHooks.noticeRecArg = NULL;
            result->noticeHooks.noticeProc = NULL;
            result->noticeHooks.noticeProcArg = NULL;
            result->client_encoding = PG_SQL_ASCII;
      }

      return result;
}

/*
 * PQsetResultAttrs
 *
 * Set the attributes for a given result.  This function fails if there are
 * already attributes contained in the provided result.  The call is
 * ignored if numAttributes is is zero or attDescs is NULL.  If the
 * function fails, it returns zero.  If the function succeeds, it
 * returns a non-zero value.
 */
int
PQsetResultAttrs(PGresult *res, int numAttributes, PGresAttDesc *attDescs)
{
      int               i;

      /* If attrs already exist, they cannot be overwritten. */
      if (!res || res->numAttributes > 0)
            return FALSE;

      /* ignore no-op request */
      if (numAttributes <= 0 || !attDescs)
            return TRUE;

      res->attDescs = (PGresAttDesc *)
            PQresultAlloc(res, numAttributes * sizeof(PGresAttDesc));

      if (!res->attDescs)
            return FALSE;

      res->numAttributes = numAttributes;
      memcpy(res->attDescs, attDescs, numAttributes * sizeof(PGresAttDesc));

      /* deep-copy the attribute names, and determine format */
      res->binary = 1;
      for (i = 0; i < res->numAttributes; i++)
      {
            if (res->attDescs[i].name)
                  res->attDescs[i].name = pqResultStrdup(res, res->attDescs[i].name);
            else
                  res->attDescs[i].name = res->null_field;

            if (!res->attDescs[i].name)
                  return FALSE;

            if (res->attDescs[i].format == 0)
                  res->binary = 0;
      }

      return TRUE;
}

/*
 * PQcopyResult
 *
 * Returns a deep copy of the provided 'src' PGresult, which cannot be NULL.
 * The 'flags' argument controls which portions of the result will or will
 * NOT be copied.  The created result is always put into the
 * PGRES_TUPLES_OK status.    The source result error message is not copied,
 * although cmdStatus is.
 *
 * To set custom attributes, use PQsetResultAttrs.    That function requires
 * that there are no attrs contained in the result, so to use that
 * function you cannot use the PG_COPYRES_ATTRS or PG_COPYRES_TUPLES
 * options with this function.
 *
 * Options:
 *     PG_COPYRES_ATTRS - Copy the source result's attributes
 *
 *     PG_COPYRES_TUPLES - Copy the source result's tuples.  This implies
 *     copying the attrs, seeeing how the attrs are needed by the tuples.
 *
 *     PG_COPYRES_EVENTS - Copy the source result's events.
 *
 *     PG_COPYRES_NOTICEHOOKS - Copy the source result's notice hooks.
 */
PGresult *
PQcopyResult(const PGresult *src, int flags)
{
      PGresult   *dest;
      int               i;

      if (!src)
            return NULL;

      dest = PQmakeEmptyPGresult(NULL, PGRES_TUPLES_OK);
      if (!dest)
            return NULL;

      /* Always copy these over.    Is cmdStatus really useful here? */
      dest->client_encoding = src->client_encoding;
      strcpy(dest->cmdStatus, src->cmdStatus);

      /* Wants attrs? */
      if (flags & (PG_COPYRES_ATTRS | PG_COPYRES_TUPLES))
      {
            if (!PQsetResultAttrs(dest, src->numAttributes, src->attDescs))
            {
                  PQclear(dest);
                  return NULL;
            }
      }

      /* Wants to copy tuples? */
      if (flags & PG_COPYRES_TUPLES)
      {
            int               tup,
                              field;

            for (tup = 0; tup < src->ntups; tup++)
            {
                  for (field = 0; field < src->numAttributes; field++)
                  {
                        if (!PQsetvalue(dest, tup, field,
                                                src->tuples[tup][field].value,
                                                src->tuples[tup][field].len))
                        {
                              PQclear(dest);
                              return NULL;
                        }
                  }
            }
      }

      /* Wants to copy notice hooks? */
      if (flags & PG_COPYRES_NOTICEHOOKS)
            dest->noticeHooks = src->noticeHooks;

      /* Wants to copy PGEvents? */
      if ((flags & PG_COPYRES_EVENTS) && src->nEvents > 0)
      {
            dest->events = dupEvents(src->events, src->nEvents);
            if (!dest->events)
            {
                  PQclear(dest);
                  return NULL;
            }
            dest->nEvents = src->nEvents;
      }

      /* Okay, trigger PGEVT_RESULTCOPY event */
      for (i = 0; i < dest->nEvents; i++)
      {
            if (src->events[i].resultInitialized)
            {
                  PGEventResultCopy evt;

                  evt.src = src;
                  evt.dest = dest;
                  if (!dest->events[i].proc(PGEVT_RESULTCOPY, &evt,
                                                        dest->events[i].passThrough))
                  {
                        PQclear(dest);
                        return NULL;
                  }
                  dest->events[i].resultInitialized = TRUE;
            }
      }

      return dest;
}

/*
 * Copy an array of PGEvents (with no extra space for more).
 * Does not duplicate the event instance data, sets this to NULL.
 * Also, the resultInitialized flags are all cleared.
 */
static PGEvent *
dupEvents(PGEvent *events, int count)
{
      PGEvent    *newEvents;
      int               i;

      if (!events || count <= 0)
            return NULL;

      newEvents = (PGEvent *) malloc(count * sizeof(PGEvent));
      if (!newEvents)
            return NULL;

      for (i = 0; i < count; i++)
      {
            newEvents[i].proc = events[i].proc;
            newEvents[i].passThrough = events[i].passThrough;
            newEvents[i].data = NULL;
            newEvents[i].resultInitialized = FALSE;
            newEvents[i].name = strdup(events[i].name);
            if (!newEvents[i].name)
            {
                  while (--i >= 0)
                        free(newEvents[i].name);
                  free(newEvents);
                  return NULL;
            }
      }

      return newEvents;
}


/*
 * Sets the value for a tuple field.  The tup_num must be less than or
 * equal to PQntuples(res).  If it is equal, a new tuple is created and
 * added to the result.
 * Returns a non-zero value for success and zero for failure.
 */
int
PQsetvalue(PGresult *res, int tup_num, int field_num, char *value, int len)
{
      PGresAttValue *attval;

      if (!check_field_number(res, field_num))
            return FALSE;

      /* Invalid tup_num, must be <= ntups */
      if (tup_num < 0 || tup_num > res->ntups)
            return FALSE;

      /* need to grow the tuple table? */
      if (res->ntups >= res->tupArrSize)
      {
            int               n = res->tupArrSize ? res->tupArrSize * 2 : 128;
            PGresAttValue **tups;

            if (res->tuples)
                  tups = (PGresAttValue **) realloc(res->tuples, n * sizeof(PGresAttValue *));
            else
                  tups = (PGresAttValue **) malloc(n * sizeof(PGresAttValue *));

            if (!tups)
                  return FALSE;

            memset(tups + res->tupArrSize, 0,
                     (n - res->tupArrSize) * sizeof(PGresAttValue *));
            res->tuples = tups;
            res->tupArrSize = n;
      }

      /* need to allocate a new tuple? */
      if (tup_num == res->ntups && !res->tuples[tup_num])
      {
            PGresAttValue *tup;
            int               i;

            tup = (PGresAttValue *)
                  pqResultAlloc(res, res->numAttributes * sizeof(PGresAttValue),
                                      TRUE);

            if (!tup)
                  return FALSE;

            /* initialize each column to NULL */
            for (i = 0; i < res->numAttributes; i++)
            {
                  tup[i].len = NULL_LEN;
                  tup[i].value = res->null_field;
            }

            res->tuples[tup_num] = tup;
            res->ntups++;
      }

      attval = &res->tuples[tup_num][field_num];

      /* treat either NULL_LEN or NULL value pointer as a NULL field */
      if (len == NULL_LEN || value == NULL)
      {
            attval->len = NULL_LEN;
            attval->value = res->null_field;
      }
      else if (len <= 0)
      {
            attval->len = 0;
            attval->value = res->null_field;
      }
      else
      {
            attval->value = (char *) pqResultAlloc(res, len + 1, TRUE);
            if (!attval->value)
                  return FALSE;
            attval->len = len;
            memcpy(attval->value, value, len);
            attval->value[len] = '\0';
      }

      return TRUE;
}

/*
 * pqResultAlloc - exported routine to allocate local storage in a PGresult.
 *
 * We force all such allocations to be maxaligned, since we don't know
 * whether the value might be binary.
 */
void *
PQresultAlloc(PGresult *res, size_t nBytes)
{
      return pqResultAlloc(res, nBytes, TRUE);
}

/*
 * 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 <= (size_t) 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
 */
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;
      int               i;

      if (!res)
            return;

      for (i = 0; i < res->nEvents; i++)
      {
            /* only send DESTROY to successfully-initialized event procs */
            if (res->events[i].resultInitialized)
            {
                  PGEventResultDestroy evt;

                  evt.result = res;
                  (void) res->events[i].proc(PGEVT_RESULTDESTROY, &evt,
                                                         res->events[i].passThrough);
            }
            free(res->events[i].name);
      }

      if (res->events)
            free(res->events);

      /* 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);

      /* zero out the pointer fields to catch programming errors */
      res->attDescs = NULL;
      res->tuples = NULL;
      res->paramDescs = NULL;
      res->errFields = NULL;
      res->events = NULL;
      res->nEvents = 0;
      /* res->curBlock was zeroed out earlier */

      /* 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.)
 */
void
pqSaveErrorResult(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.
 */
PGresult *
pqPrepareAsyncResult(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;
}

/*
 * pqInternalNotice - produce an internally-generated notice message
 *
 * A format string and optional arguments can be passed.  Note that we do
 * libpq_gettext() here, so callers need not.
 *
 * The supplied text is taken as primary message (ie., it should not include
 * a trailing newline, and should not be more than one line).
 */
void
pqInternalNotice(const PGNoticeHooks *hooks, const char *fmt,...)
{
      char        msgBuf[1024];
      va_list           args;
      PGresult   *res;

      if (hooks->noticeRec == NULL)
            return;                             /* nobody home to receive notice? */

      /* Format the message */
      va_start(args, fmt);
      vsnprintf(msgBuf, sizeof(msgBuf), libpq_gettext(fmt), args);
      va_end(args);
      msgBuf[sizeof(msgBuf) - 1] = '\0';  /* make real sure it's terminated */

      /* Make a PGresult to pass to the notice receiver */
      res = PQmakeEmptyPGresult(NULL, PGRES_NONFATAL_ERROR);
      if (!res)
            return;
      res->noticeHooks = *hooks;

      /*
       * Set up fields of notice.
       */
      pqSaveMessageField(res, PG_DIAG_MESSAGE_PRIMARY, msgBuf);
      pqSaveMessageField(res, PG_DIAG_SEVERITY, libpq_gettext("NOTICE"));
      /* XXX should provide a SQLSTATE too? */

      /*
       * Result text is always just the primary message + newline. If we can't
       * allocate it, don't bother invoking the receiver.
       */
      res->errMsg = (char *) pqResultAlloc(res, strlen(msgBuf) + 2, FALSE);
      if (res->errMsg)
      {
            sprintf(res->errMsg, "%s\n", msgBuf);

            /*
             * Pass to receiver, then free it.
             */
            (*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res);
      }
      PQclear(res);
}

/*
 * pqAddTuple
 *      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
 */
int
pqAddTuple(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;
}

/*
 * pqSaveMessageField - save one field of an error or notice message
 */
void
pqSaveMessageField(PGresult *res, char code, const char *value)
{
      PGMessageField *pfield;

      pfield = (PGMessageField *)
            pqResultAlloc(res,
                                sizeof(PGMessageField) + strlen(value),
                                TRUE);
      if (!pfield)
            return;                             /* out of memory? */
      pfield->code = code;
      strcpy(pfield->contents, value);
      pfield->next = res->errFields;
      res->errFields = pfield;
}

/*
 * pqSaveParameterStatus - remember parameter status sent by backend
 */
void
pqSaveParameterStatus(PGconn *conn, const char *name, const char *value)
{
      pgParameterStatus *pstatus;
      pgParameterStatus *prev;

      if (conn->Pfdebug)
            fprintf(conn->Pfdebug, "pqSaveParameterStatus: '%s' = '%s'\n",
                        name, value);

      /*
       * Forget any old information about the parameter
       */
      for (pstatus = conn->pstatus, prev = NULL;
             pstatus != NULL;
             prev = pstatus, pstatus = pstatus->next)
      {
            if (strcmp(pstatus->name, name) == 0)
            {
                  if (prev)
                        prev->next = pstatus->next;
                  else
                        conn->pstatus = pstatus->next;
                  free(pstatus);          /* frees name and value strings too */
                  break;
            }
      }

      /*
       * Store new info as a single malloc block
       */
      pstatus = (pgParameterStatus *) malloc(sizeof(pgParameterStatus) +
                                                               strlen(name) +strlen(value) + 2);
      if (pstatus)
      {
            char     *ptr;

            ptr = ((char *) pstatus) + sizeof(pgParameterStatus);
            pstatus->name = ptr;
            strcpy(ptr, name);
            ptr += strlen(name) + 1;
            pstatus->value = ptr;
            strcpy(ptr, value);
            pstatus->next = conn->pstatus;
            conn->pstatus = pstatus;
      }

      /*
       * Special hacks: remember client_encoding and
       * standard_conforming_strings, and convert server version to a numeric
       * form.  We keep the first two of these in static variables as well, so
       * that PQescapeString and PQescapeBytea can behave somewhat sanely (at
       * least in single-connection-using programs).
       */
      if (strcmp(name, "client_encoding") == 0)
      {
            conn->client_encoding = pg_char_to_encoding(value);
            /* if we don't recognize the encoding name, fall back to SQL_ASCII */
            if (conn->client_encoding < 0)
                  conn->client_encoding = PG_SQL_ASCII;
            static_client_encoding = conn->client_encoding;
      }
      else if (strcmp(name, "standard_conforming_strings") == 0)
      {
            conn->std_strings = (strcmp(value, "on") == 0);
            static_std_strings = conn->std_strings;
      }
      else if (strcmp(name, "server_version") == 0)
      {
            int               cnt;
            int               vmaj,
                              vmin,
                              vrev;

            cnt = sscanf(value, "%d.%d.%d", &vmaj, &vmin, &vrev);

            if (cnt < 2)
                  conn->sversion = 0; /* unknown */
            else
            {
                  if (cnt == 2)
                        vrev = 0;
                  conn->sversion = (100 * vmaj + vmin) * 100 + vrev;
            }
      }
}


/*
 * 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 (!PQsendQueryStart(conn))
            return 0;

      if (!query)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                    libpq_gettext("command string is a null pointer\n"));
            return 0;
      }

      /* construct the outgoing Query message */
      if (pqPutMsgStart('Q', false, conn) < 0 ||
            pqPuts(query, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
      {
            pqHandleSendFailure(conn);
            return 0;
      }

      /* remember we are using simple query protocol */
      conn->queryclass = PGQUERY_SIMPLE;

      /* and remember the query text too, if possible */
      /* if insufficient memory, last_query just winds up NULL */
      if (conn->last_query)
            free(conn->last_query);
      conn->last_query = strdup(query);

      /*
       * Give the data a push.  In nonblock mode, don't complain if we're unable
       * to send it all; PQgetResult() will do any additional flushing needed.
       */
      if (pqFlush(conn) < 0)
      {
            pqHandleSendFailure(conn);
            return 0;
      }

      /* OK, it's launched! */
      conn->asyncStatus = PGASYNC_BUSY;
      return 1;
}

/*
 * PQsendQueryParams
 *          Like PQsendQuery, but use protocol 3.0 so we can pass parameters
 */
int
PQsendQueryParams(PGconn *conn,
                          const char *command,
                          int nParams,
                          const Oid *paramTypes,
                          const char *const * paramValues,
                          const int *paramLengths,
                          const int *paramFormats,
                          int resultFormat)
{
      if (!PQsendQueryStart(conn))
            return 0;

      if (!command)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                    libpq_gettext("command string is a null pointer\n"));
            return 0;
      }

      return PQsendQueryGuts(conn,
                                       command,
                                       "",      /* use unnamed statement */
                                       nParams,
                                       paramTypes,
                                       paramValues,
                                       paramLengths,
                                       paramFormats,
                                       resultFormat);
}

/*
 * PQsendPrepare
 *     Submit a Parse message, but don't wait for it to finish
 *
 * Returns: 1 if successfully submitted
 *                0 if error (conn->errorMessage is set)
 */
int
PQsendPrepare(PGconn *conn,
                    const char *stmtName, const char *query,
                    int nParams, const Oid *paramTypes)
{
      if (!PQsendQueryStart(conn))
            return 0;

      if (!stmtName)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                    libpq_gettext("statement name is a null pointer\n"));
            return 0;
      }

      if (!query)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                    libpq_gettext("command string is a null pointer\n"));
            return 0;
      }

      /* This isn't gonna work on a 2.0 server */
      if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
      {
            printfPQExpBuffer(&conn->errorMessage,
             libpq_gettext("function requires at least protocol version 3.0\n"));
            return 0;
      }

      /* construct the Parse message */
      if (pqPutMsgStart('P', false, conn) < 0 ||
            pqPuts(stmtName, conn) < 0 ||
            pqPuts(query, conn) < 0)
            goto sendFailed;

      if (nParams > 0 && paramTypes)
      {
            int               i;

            if (pqPutInt(nParams, 2, conn) < 0)
                  goto sendFailed;
            for (i = 0; i < nParams; i++)
            {
                  if (pqPutInt(paramTypes[i], 4, conn) < 0)
                        goto sendFailed;
            }
      }
      else
      {
            if (pqPutInt(0, 2, conn) < 0)
                  goto sendFailed;
      }
      if (pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* construct the Sync message */
      if (pqPutMsgStart('S', false, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* remember we are doing just a Parse */
      conn->queryclass = PGQUERY_PREPARE;

      /* and remember the query text too, if possible */
      /* if insufficient memory, last_query just winds up NULL */
      if (conn->last_query)
            free(conn->last_query);
      conn->last_query = strdup(query);

      /*
       * Give the data a push.  In nonblock mode, don't complain if we're unable
       * to send it all; PQgetResult() will do any additional flushing needed.
       */
      if (pqFlush(conn) < 0)
            goto sendFailed;

      /* OK, it's launched! */
      conn->asyncStatus = PGASYNC_BUSY;
      return 1;

sendFailed:
      pqHandleSendFailure(conn);
      return 0;
}

/*
 * PQsendQueryPrepared
 *          Like PQsendQuery, but execute a previously prepared statement,
 *          using protocol 3.0 so we can pass parameters
 */
int
PQsendQueryPrepared(PGconn *conn,
                              const char *stmtName,
                              int nParams,
                              const char *const * paramValues,
                              const int *paramLengths,
                              const int *paramFormats,
                              int resultFormat)
{
      if (!PQsendQueryStart(conn))
            return 0;

      if (!stmtName)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                    libpq_gettext("statement name is a null pointer\n"));
            return 0;
      }

      return PQsendQueryGuts(conn,
                                       NULL,    /* no command to parse */
                                       stmtName,
                                       nParams,
                                       NULL,    /* no param types */
                                       paramValues,
                                       paramLengths,
                                       paramFormats,
                                       resultFormat);
}

/*
 * Common startup code for PQsendQuery and sibling routines
 */
static bool
PQsendQueryStart(PGconn *conn)
{
      if (!conn)
            return false;

      /* clear the error string */
      resetPQExpBuffer(&conn->errorMessage);

      /* Don't try to send if we know there's no live connection. */
      if (conn->status != CONNECTION_OK)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("no connection to the server\n"));
            return false;
      }
      /* Can't send while already busy, either. */
      if (conn->asyncStatus != PGASYNC_IDLE)
      {
            printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("another command is already in progress\n"));
            return false;
      }

      /* initialize async result-accumulation state */
      conn->result = NULL;
      conn->curTuple = NULL;

      /* ready to send command message */
      return true;
}

/*
 * PQsendQueryGuts
 *          Common code for protocol-3.0 query sending
 *          PQsendQueryStart should be done already
 *
 * command may be NULL to indicate we use an already-prepared statement
 */
static int
PQsendQueryGuts(PGconn *conn,
                        const char *command,
                        const char *stmtName,
                        int nParams,
                        const Oid *paramTypes,
                        const char *const * paramValues,
                        const int *paramLengths,
                        const int *paramFormats,
                        int resultFormat)
{
      int               i;

      /* This isn't gonna work on a 2.0 server */
      if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
      {
            printfPQExpBuffer(&conn->errorMessage,
             libpq_gettext("function requires at least protocol version 3.0\n"));
            return 0;
      }

      /*
       * We will send Parse (if needed), Bind, Describe Portal, Execute, Sync,
       * using specified statement name and the unnamed portal.
       */

      if (command)
      {
            /* construct the Parse message */
            if (pqPutMsgStart('P', false, conn) < 0 ||
                  pqPuts(stmtName, conn) < 0 ||
                  pqPuts(command, conn) < 0)
                  goto sendFailed;
            if (nParams > 0 && paramTypes)
            {
                  if (pqPutInt(nParams, 2, conn) < 0)
                        goto sendFailed;
                  for (i = 0; i < nParams; i++)
                  {
                        if (pqPutInt(paramTypes[i], 4, conn) < 0)
                              goto sendFailed;
                  }
            }
            else
            {
                  if (pqPutInt(0, 2, conn) < 0)
                        goto sendFailed;
            }
            if (pqPutMsgEnd(conn) < 0)
                  goto sendFailed;
      }

      /* Construct the Bind message */
      if (pqPutMsgStart('B', false, conn) < 0 ||
            pqPuts("", conn) < 0 ||
            pqPuts(stmtName, conn) < 0)
            goto sendFailed;

      /* Send parameter formats */
      if (nParams > 0 && paramFormats)
      {
            if (pqPutInt(nParams, 2, conn) < 0)
                  goto sendFailed;
            for (i = 0; i < nParams; i++)
            {
                  if (pqPutInt(paramFormats[i], 2, conn) < 0)
                        goto sendFailed;
            }
      }
      else
      {
            if (pqPutInt(0, 2, conn) < 0)
                  goto sendFailed;
      }

      if (pqPutInt(nParams, 2, conn) < 0)
            goto sendFailed;

      /* Send parameters */
      for (i = 0; i < nParams; i++)
      {
            if (paramValues && paramValues[i])
            {
                  int               nbytes;

                  if (paramFormats && paramFormats[i] != 0)
                  {
                        /* binary parameter */
                        if (paramLengths)
                              nbytes = paramLengths[i];
                        else
                        {
                              printfPQExpBuffer(&conn->errorMessage,
                                                        libpq_gettext("length must be given for binary parameter\n"));
                              goto sendFailed;
                        }
                  }
                  else
                  {
                        /* text parameter, do not use paramLengths */
                        nbytes = strlen(paramValues[i]);
                  }
                  if (pqPutInt(nbytes, 4, conn) < 0 ||
                        pqPutnchar(paramValues[i], nbytes, conn) < 0)
                        goto sendFailed;
            }
            else
            {
                  /* take the param as NULL */
                  if (pqPutInt(-1, 4, conn) < 0)
                        goto sendFailed;
            }
      }
      if (pqPutInt(1, 2, conn) < 0 ||
            pqPutInt(resultFormat, 2, conn))
            goto sendFailed;
      if (pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* construct the Describe Portal message */
      if (pqPutMsgStart('D', false, conn) < 0 ||
            pqPutc('P', conn) < 0 ||
            pqPuts("", conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* construct the Execute message */
      if (pqPutMsgStart('E', false, conn) < 0 ||
            pqPuts("", conn) < 0 ||
            pqPutInt(0, 4, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* construct the Sync message */
      if (pqPutMsgStart('S', false, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* remember we are using extended query protocol */
      conn->queryclass = PGQUERY_EXTENDED;

      /* and remember the query text too, if possible */
      /* if insufficient memory, last_query just winds up NULL */
      if (conn->last_query)
            free(conn->last_query);
      if (command)
            conn->last_query = strdup(command);
      else
            conn->last_query = NULL;

      /*
       * Give the data a push.  In nonblock mode, don't complain if we're unable
       * to send it all; PQgetResult() will do any additional flushing needed.
       */
      if (pqFlush(conn) < 0)
            goto sendFailed;

      /* OK, it's launched! */
      conn->asyncStatus = PGASYNC_BUSY;
      return 1;

sendFailed:
      pqHandleSendFailure(conn);
      return 0;
}

/*
 * pqHandleSendFailure: 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.
 */
void
pqHandleSendFailure(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;

      /*
       * for non-blocking connections try to flush the send-queue, otherwise we
       * may never get a response for something that may not have already been
       * sent because it's in our write buffer!
       */
      if (pqIsnonblocking(conn))
      {
            if (pqFlush(conn) < 0)
                  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)
            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)
{
      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            pqParseInput3(conn);
      else
            pqParseInput2(conn);
}

/*
 * 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 no
 *      query work remains or an error has occurred (e.g. out of
 *      memory).
 */

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)
      {
            int               flushResult;

            /*
             * If data remains unsent, send it.  Else we might be waiting for the
             * result of a command the backend hasn't even got yet.
             */
            while ((flushResult = pqFlush(conn)) > 0)
            {
                  if (pqWait(FALSE, TRUE, conn))
                  {
                        flushResult = -1;
                        break;
                  }
            }

            /* Wait for some more data, and load it. */
            if (flushResult ||
                  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.
                   */
                  pqSaveErrorResult(conn);
                  conn->asyncStatus = PGASYNC_IDLE;
                  return pqPrepareAsyncResult(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 = pqPrepareAsyncResult(conn);
                  /* Set the state back to BUSY, allowing parsing to proceed. */
                  conn->asyncStatus = PGASYNC_BUSY;
                  break;
            case PGASYNC_COPY_IN:
                  if (conn->result && conn->result->resultStatus == PGRES_COPY_IN)
                        res = pqPrepareAsyncResult(conn);
                  else
                        res = PQmakeEmptyPGresult(conn, PGRES_COPY_IN);
                  break;
            case PGASYNC_COPY_OUT:
                  if (conn->result && conn->result->resultStatus == PGRES_COPY_OUT)
                        res = pqPrepareAsyncResult(conn);
                  else
                        res = PQmakeEmptyPGresult(conn, PGRES_COPY_OUT);
                  break;
            default:
                  printfPQExpBuffer(&conn->errorMessage,
                                            libpq_gettext("unexpected asyncStatus: %d\n"),
                                            (int) conn->asyncStatus);
                  res = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
                  break;
      }

      if (res)
      {
            int               i;

            for (i = 0; i < res->nEvents; i++)
            {
                  PGEventResultCreate evt;

                  evt.conn = conn;
                  evt.result = res;
                  if (!res->events[i].proc(PGEVT_RESULTCREATE, &evt,
                                                       res->events[i].passThrough))
                  {
                        printfPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("PGEventProc \"%s\" failed during PGEVT_RESULTCREATE event\n"),
                                                  res->events[i].name);
                        pqSetResultError(res, conn->errorMessage.data);
                        res->resultStatus = PGRES_FATAL_ERROR;
                        break;
                  }
                  res->events[i].resultInitialized = TRUE;
            }
      }

      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)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendQuery(conn, query))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * PQexecParams
 *          Like PQexec, but use protocol 3.0 so we can pass parameters
 */
PGresult *
PQexecParams(PGconn *conn,
                   const char *command,
                   int nParams,
                   const Oid *paramTypes,
                   const char *const * paramValues,
                   const int *paramLengths,
                   const int *paramFormats,
                   int resultFormat)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendQueryParams(conn, command,
                                       nParams, paramTypes, paramValues, paramLengths,
                                       paramFormats, resultFormat))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * PQprepare
 *      Creates a prepared statement by issuing a v3.0 parse message.
 *
 * 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 *
PQprepare(PGconn *conn,
              const char *stmtName, const char *query,
              int nParams, const Oid *paramTypes)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendPrepare(conn, stmtName, query, nParams, paramTypes))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * PQexecPrepared
 *          Like PQexec, but execute a previously prepared statement,
 *          using protocol 3.0 so we can pass parameters
 */
PGresult *
PQexecPrepared(PGconn *conn,
                     const char *stmtName,
                     int nParams,
                     const char *const * paramValues,
                     const int *paramLengths,
                     const int *paramFormats,
                     int resultFormat)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendQueryPrepared(conn, stmtName,
                                           nParams, paramValues, paramLengths,
                                           paramFormats, resultFormat))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * Common code for PQexec and sibling routines: prepare to send command
 */
static bool
PQexecStart(PGconn *conn)
{
      PGresult   *result;

      if (!conn)
            return false;

      /*
       * 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)
      {
            ExecStatusType resultStatus = result->resultStatus;

            PQclear(result);        /* only need its status */
            if (resultStatus == PGRES_COPY_IN)
            {
                  if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                  {
                        /* In protocol 3, we can get out of a COPY IN state */
                        if (PQputCopyEnd(conn,
                                     libpq_gettext("COPY terminated by new PQexec")) < 0)
                              return false;
                        /* keep waiting to swallow the copy's failure message */
                  }
                  else
                  {
                        /* In older protocols we have to punt */
                        printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("COPY IN state must be terminated first\n"));
                        return false;
                  }
            }
            else if (resultStatus == PGRES_COPY_OUT)
            {
                  if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                  {
                        /*
                         * In protocol 3, we can get out of a COPY OUT state: we just
                         * switch back to BUSY and allow the remaining COPY data to be
                         * dropped on the floor.
                         */
                        conn->asyncStatus = PGASYNC_BUSY;
                        /* keep waiting to swallow the copy's completion message */
                  }
                  else
                  {
                        /* In older protocols we have to punt */
                        printfPQExpBuffer(&conn->errorMessage,
                         libpq_gettext("COPY OUT state must be terminated first\n"));
                        return false;
                  }
            }
            /* check for loss of connection, too */
            if (conn->status == CONNECTION_BAD)
                  return false;
      }

      /* OK to send a command */
      return true;
}

/*
 * Common code for PQexec and sibling routines: wait for command result
 */
static PGresult *
PQexecFinish(PGconn *conn)
{
      PGresult   *result;
      PGresult   *lastResult;

      /*
       * 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
       * after application performs the data transfer.
       *
       * Also stop if the connection is lost (else we'll loop infinitely).
       */
      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 concatenated 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 ||
                  conn->status == CONNECTION_BAD)
                  break;
      }

      return lastResult;
}

/*
 * PQdescribePrepared
 *      Obtain information about a previously prepared statement
 *
 * 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).      On success, the PGresult contains status
 * PGRES_COMMAND_OK, and its parameter and column-heading fields describe
 * the statement's inputs and outputs respectively.
 * The user is responsible for freeing the PGresult via PQclear()
 * when done with it.
 */
PGresult *
PQdescribePrepared(PGconn *conn, const char *stmt)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendDescribe(conn, 'S', stmt))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * PQdescribePortal
 *      Obtain information about a previously created portal
 *
 * This is much like PQdescribePrepared, except that no parameter info is
 * returned.  Note that at the moment, libpq doesn't really expose portals
 * to the client; but this can be used with a portal created by a SQL
 * DECLARE CURSOR command.
 */
PGresult *
PQdescribePortal(PGconn *conn, const char *portal)
{
      if (!PQexecStart(conn))
            return NULL;
      if (!PQsendDescribe(conn, 'P', portal))
            return NULL;
      return PQexecFinish(conn);
}

/*
 * PQsendDescribePrepared
 *     Submit a Describe Statement command, but don't wait for it to finish
 *
 * Returns: 1 if successfully submitted
 *                0 if error (conn->errorMessage is set)
 */
int
PQsendDescribePrepared(PGconn *conn, const char *stmt)
{
      return PQsendDescribe(conn, 'S', stmt);
}

/*
 * PQsendDescribePortal
 *     Submit a Describe Portal command, but don't wait for it to finish
 *
 * Returns: 1 if successfully submitted
 *                0 if error (conn->errorMessage is set)
 */
int
PQsendDescribePortal(PGconn *conn, const char *portal)
{
      return PQsendDescribe(conn, 'P', portal);
}

/*
 * PQsendDescribe
 *     Common code to send a Describe command
 *
 * Available options for desc_type are
 *     'S' to describe a prepared statement; or
 *     'P' to describe a portal.
 * Returns 1 on success and 0 on failure.
 */
static int
PQsendDescribe(PGconn *conn, char desc_type, const char *desc_target)
{
      /* Treat null desc_target as empty string */
      if (!desc_target)
            desc_target = "";

      if (!PQsendQueryStart(conn))
            return 0;

      /* This isn't gonna work on a 2.0 server */
      if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
      {
            printfPQExpBuffer(&conn->errorMessage,
             libpq_gettext("function requires at least protocol version 3.0\n"));
            return 0;
      }

      /* construct the Describe message */
      if (pqPutMsgStart('D', false, conn) < 0 ||
            pqPutc(desc_type, conn) < 0 ||
            pqPuts(desc_target, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* construct the Sync message */
      if (pqPutMsgStart('S', false, conn) < 0 ||
            pqPutMsgEnd(conn) < 0)
            goto sendFailed;

      /* remember we are doing a Describe */
      conn->queryclass = PGQUERY_DESCRIBE;

      /* reset last-query string (not relevant now) */
      if (conn->last_query)
      {
            free(conn->last_query);
            conn->last_query = NULL;
      }

      /*
       * Give the data a push.  In nonblock mode, don't complain if we're unable
       * to send it all; PQgetResult() will do any additional flushing needed.
       */
      if (pqFlush(conn) < 0)
            goto sendFailed;

      /* OK, it's launched! */
      conn->asyncStatus = PGASYNC_BUSY;
      return 1;

sendFailed:
      pqHandleSendFailure(conn);
      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)
{
      PGnotify   *event;

      if (!conn)
            return NULL;

      /* Parse any available data to see if we can extract NOTIFY messages. */
      parseInput(conn);

      event = conn->notifyHead;
      if (event)
      {
            conn->notifyHead = event->next;
            if (!conn->notifyHead)
                  conn->notifyTail = NULL;
            event->next = NULL;           /* don't let app see the internal state */
      }
      return event;
}

/*
 * PQputCopyData - send some data to the backend during COPY IN
 *
 * Returns 1 if successful, 0 if data could not be sent (only possible
 * in nonblock mode), or -1 if an error occurs.
 */
int
PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
{
      if (!conn)
            return -1;
      if (conn->asyncStatus != PGASYNC_COPY_IN)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("no COPY in progress\n"));
            return -1;
      }

      /*
       * Process any NOTICE or NOTIFY messages that might be pending in the
       * input buffer.  Since the server might generate many notices during the
       * COPY, we want to clean those out reasonably promptly to prevent
       * indefinite expansion of the input buffer.  (Note: the actual read of
       * input data into the input buffer happens down inside pqSendSome, but
       * it's not authorized to get rid of the data again.)
       */
      parseInput(conn);

      if (nbytes > 0)
      {
            /*
             * Try to flush any previously sent data in preference to growing the
             * output buffer.  If we can't enlarge the buffer enough to hold the
             * data, return 0 in the nonblock case, else hard error. (For
             * simplicity, always assume 5 bytes of overhead even in protocol 2.0
             * case.)
             */
            if ((conn->outBufSize - conn->outCount - 5) < nbytes)
            {
                  if (pqFlush(conn) < 0)
                        return -1;
                  if (pqCheckOutBufferSpace(conn->outCount + 5 + (size_t) nbytes,
                                                        conn))
                        return pqIsnonblocking(conn) ? 0 : -1;
            }
            /* Send the data (too simple to delegate to fe-protocol files) */
            if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            {
                  if (pqPutMsgStart('d', false, conn) < 0 ||
                        pqPutnchar(buffer, nbytes, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }
            else
            {
                  if (pqPutMsgStart(0, false, conn) < 0 ||
                        pqPutnchar(buffer, nbytes, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }
      }
      return 1;
}

/*
 * PQputCopyEnd - send EOF indication to the backend during COPY IN
 *
 * After calling this, use PQgetResult() to check command completion status.
 *
 * Returns 1 if successful, 0 if data could not be sent (only possible
 * in nonblock mode), or -1 if an error occurs.
 */
int
PQputCopyEnd(PGconn *conn, const char *errormsg)
{
      if (!conn)
            return -1;
      if (conn->asyncStatus != PGASYNC_COPY_IN)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("no COPY in progress\n"));
            return -1;
      }

      /*
       * Send the COPY END indicator.  This is simple enough that we don't
       * bother delegating it to the fe-protocol files.
       */
      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
      {
            if (errormsg)
            {
                  /* Send COPY FAIL */
                  if (pqPutMsgStart('f', false, conn) < 0 ||
                        pqPuts(errormsg, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }
            else
            {
                  /* Send COPY DONE */
                  if (pqPutMsgStart('c', false, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }

            /*
             * If we sent the COPY command in extended-query mode, we must issue a
             * Sync as well.
             */
            if (conn->queryclass != PGQUERY_SIMPLE)
            {
                  if (pqPutMsgStart('S', false, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }
      }
      else
      {
            if (errormsg)
            {
                  /* Ooops, no way to do this in 2.0 */
                  printfPQExpBuffer(&conn->errorMessage,
                                            libpq_gettext("function requires at least protocol version 3.0\n"));
                  return -1;
            }
            else
            {
                  /* Send old-style end-of-data marker */
                  if (pqPutMsgStart(0, false, conn) < 0 ||
                        pqPutnchar("\\.\n", 3, conn) < 0 ||
                        pqPutMsgEnd(conn) < 0)
                        return -1;
            }
      }

      /* Return to active duty */
      conn->asyncStatus = PGASYNC_BUSY;
      resetPQExpBuffer(&conn->errorMessage);

      /* Try to flush data */
      if (pqFlush(conn) < 0)
            return -1;

      return 1;
}

/*
 * 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
PQgetCopyData(PGconn *conn, char **buffer, int async)
{
      *buffer = NULL;                     /* for all failure cases */
      if (!conn)
            return -2;
      if (conn->asyncStatus != PGASYNC_COPY_OUT)
      {
            printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("no COPY in progress\n"));
            return -2;
      }
      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            return pqGetCopyData3(conn, buffer, async);
      else
            return pqGetCopyData2(conn, buffer, async);
}

/*
 * 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.
 *
 * XXX this routine is now deprecated, because it can't handle binary data.
 * If called during a COPY BINARY we return EOF.
 *
 * 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 error (eg, 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)
{
      if (!s || maxlen <= 0)
            return EOF;
      *s = '\0';
      /* maxlen must be at least 3 to hold the \. terminator! */
      if (maxlen < 3)
            return EOF;

      if (!conn)
            return EOF;

      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            return pqGetline3(conn, s, maxlen);
      else
            return pqGetline2(conn, s, maxlen);
}

/*
 * PQgetlineAsync - gets a COPY data row 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 data row
 * is available in libpq's input buffer.  Otherwise, no data is returned
 * until the rest of the row 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 data-row boundary.  If possible
 * a whole row will be returned at one time.  But if the buffer offered by
 * the caller is too small to hold a row sent by the backend, then a partial
 * data row will be returned.  In text mode this can be detected by testing
 * whether the last returned byte is '\n' or not.
 *
 * The returned data is *not* null-terminated.
 */

int
PQgetlineAsync(PGconn *conn, char *buffer, int bufsize)
{
      if (!conn)
            return -1;

      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            return pqGetlineAsync3(conn, buffer, bufsize);
      else
            return pqGetlineAsync2(conn, buffer, bufsize);
}

/*
 * PQputline -- sends a string to the backend during COPY IN.
 * Returns 0 if OK, EOF if not.
 *
 * This is deprecated primarily because the return convention doesn't allow
 * caller to tell the difference between a hard error and a nonblock-mode
 * send failure.
 */
int
PQputline(PGconn *conn, const char *s)
{
      return PQputnbytes(conn, s, strlen(s));
}

/*
 * 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 (PQputCopyData(conn, buffer, nbytes) > 0)
            return 0;
      else
            return EOF;
}

/*
 * PQendcopy
 *          After completing the data transfer portion of a copy in/out,
 *          the application must call this routine to finish the command protocol.
 *
 * When using protocol 3.0 this is deprecated; it's cleaner to use PQgetResult
 * to get the transfer status.      Note however that when using 2.0 protocol,
 * recovering from a copy failure often requires a PQreset.  PQendcopy will
 * take care of that, PQgetResult won't.
 *
 * RETURNS:
 *          0 on success
 *          1 on failure
 */
int
PQendcopy(PGconn *conn)
{
      if (!conn)
            return 0;

      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            return pqEndcopy3(conn);
      else
            return pqEndcopy2(conn);
}


/* ----------------
 *          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)
{
      *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,
                                      libpq_gettext("connection in wrong state\n"));
            return NULL;
      }

      if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
            return pqFunctionCall3(conn, fnid,
                                             result_buf, actual_result_len,
                                             result_is_int,
                                             args, nargs);
      else
            return pqFunctionCall2(conn, fnid,
                                             result_buf, actual_result_len,
                                             result_is_int,
                                             args, nargs);
}


/* ====== accessor funcs for PGresult ======== */

ExecStatusType
PQresultStatus(const PGresult *res)
{
      if (!res)
            return PGRES_FATAL_ERROR;
      return res->resultStatus;
}

char *
PQresStatus(ExecStatusType status)
{
      if (status < 0 || status >= sizeof pgresStatus / sizeof pgresStatus[0])
            return libpq_gettext("invalid ExecStatusType code");
      return pgresStatus[status];
}

char *
PQresultErrorMessage(const PGresult *res)
{
      if (!res || !res->errMsg)
            return "";
      return res->errMsg;
}

char *
PQresultErrorField(const PGresult *res, int fieldcode)
{
      PGMessageField *pfield;

      if (!res)
            return NULL;
      for (pfield = res->errFields; pfield != NULL; pfield = pfield->next)
      {
            if (pfield->code == fieldcode)
                  return pfield->contents;
      }
      return NULL;
}

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 PGresult *res, int field_num)
{
      if (!res)
            return FALSE;                 /* no way to display error message... */
      if (field_num < 0 || field_num >= res->numAttributes)
      {
            pqInternalNotice(&res->noticeHooks,
                                     "column number %d is out of range 0..%d",
                                     field_num, res->numAttributes - 1);
            return FALSE;
      }
      return TRUE;
}

static int
check_tuple_field_number(const PGresult *res,
                                     int tup_num, int field_num)
{
      if (!res)
            return FALSE;                 /* no way to display error message... */
      if (tup_num < 0 || tup_num >= res->ntups)
      {
            pqInternalNotice(&res->noticeHooks,
                                     "row number %d is out of range 0..%d",
                                     tup_num, res->ntups - 1);
            return FALSE;
      }
      if (field_num < 0 || field_num >= res->numAttributes)
      {
            pqInternalNotice(&res->noticeHooks,
                                     "column number %d is out of range 0..%d",
                                     field_num, res->numAttributes - 1);
            return FALSE;
      }
      return TRUE;
}

static int
check_param_number(const PGresult *res, int param_num)
{
      if (!res)
            return FALSE;                 /* no way to display error message... */
      if (param_num < 0 || param_num >= res->numParameters)
      {
            pqInternalNotice(&res->noticeHooks,
                                     "parameter number %d is out of range 0..%d",
                                     param_num, res->numParameters - 1);
            return FALSE;
      }

      return TRUE;
}

/*
 * returns NULL if the field_num is invalid
 */
char *
PQfname(const PGresult *res, int field_num)
{
      if (!check_field_number(res, field_num))
            return NULL;
      if (res->attDescs)
            return res->attDescs[field_num].name;
      else
            return NULL;
}

/*
 * PQfnumber: find column number given column name
 *
 * The column name is parsed as if it were in a SQL statement, including
 * case-folding and double-quote processing.  But note a possible gotcha:
 * downcasing in the frontend might follow different locale rules than
 * downcasing in the backend...
 *
 * Returns -1 if no match.    In the present backend it is also possible
 * to have multiple matches, in which case the first one is found.
 */
int
PQfnumber(const PGresult *res, const char *field_name)
{
      char     *field_case;
      bool        in_quotes;
      char     *iptr;
      char     *optr;
      int               i;

      if (!res)
            return -1;

      /*
       * Note: it is correct to reject a zero-length input string; the proper
       * input to match a zero-length field name would be "".
       */
      if (field_name == NULL ||
            field_name[0] == '\0' ||
            res->attDescs == NULL)
            return -1;

      /*
       * Note: this code will not reject partially quoted strings, eg
       * foo"BAR"foo will become fooBARfoo when it probably ought to be an error
       * condition.
       */
      field_case = strdup(field_name);
      if (field_case == NULL)
            return -1;                    /* grotty */

      in_quotes = false;
      optr = field_case;
      for (iptr = field_case; *iptr; iptr++)
      {
            char        c = *iptr;

            if (in_quotes)
            {
                  if (c == '"')
                  {
                        if (iptr[1] == '"')
                        {
                              /* doubled quotes become a single quote */
                              *optr++ = '"';
                              iptr++;
                        }
                        else
                              in_quotes = false;
                  }
                  else
                        *optr++ = c;
            }
            else if (c == '"')
                  in_quotes = true;
            else
            {
                  c = pg_tolower((unsigned char) c);
                  *optr++ = c;
            }
      }
      *optr = '\0';

      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
PQftable(const PGresult *res, int field_num)
{
      if (!check_field_number(res, field_num))
            return InvalidOid;
      if (res->attDescs)
            return res->attDescs[field_num].tableid;
      else
            return InvalidOid;
}

int
PQftablecol(const PGresult *res, int field_num)
{
      if (!check_field_number(res, field_num))
            return 0;
      if (res->attDescs)
            return res->attDescs[field_num].columnid;
      else
            return 0;
}

int
PQfformat(const PGresult *res, int field_num)
{
      if (!check_field_number(res, field_num))
            return 0;
      if (res->attDescs)
            return res->attDescs[field_num].format;
      else
            return 0;
}

Oid
PQftype(const PGresult *res, int field_num)
{
      if (!check_field_number(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(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(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[len] = '\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;
      unsigned long result;

      if (!res ||
            !res->cmdStatus ||
            strncmp(res->cmdStatus, "INSERT ", 7) != 0 ||
            res->cmdStatus[7] < '0' ||
            res->cmdStatus[7] > '9')
            return InvalidOid;

      result = strtoul(res->cmdStatus + 7, &endptr, 10);

      if (!endptr || (*endptr != ' ' && *endptr != '\0'))
            return InvalidOid;
      else
            return (Oid) result;
}


/*
 * PQcmdTuples -
 *    If the last command was INSERT/UPDATE/DELETE/MOVE/FETCH/COPY, return
 *    a string containing the number of inserted/affected tuples. If not,
 *    return "".
 *
 *    XXX: this should probably return an int
 */
char *
PQcmdTuples(PGresult *res)
{
      char     *p,
                     *c;

      if (!res)
            return "";

      if (strncmp(res->cmdStatus, "INSERT ", 7) == 0)
      {
            p = res->cmdStatus + 7;
            /* INSERT: skip oid and space */
            while (*p && *p != ' ')
                  p++;
            if (*p == 0)
                  goto interpret_error;         /* no space? */
            p++;
      }
      else if (strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
                   strncmp(res->cmdStatus, "UPDATE ", 7) == 0)
            p = res->cmdStatus + 7;
      else if (strncmp(res->cmdStatus, "FETCH ", 6) == 0)
            p = res->cmdStatus + 6;
      else if (strncmp(res->cmdStatus, "MOVE ", 5) == 0 ||
                   strncmp(res->cmdStatus, "COPY ", 5) == 0)
            p = res->cmdStatus + 5;
      else
            return "";

      /* check that we have an integer (at least one digit, nothing else) */
      for (c = p; *c; c++)
      {
            if (!isdigit((unsigned char) *c))
                  goto interpret_error;
      }
      if (c == p)
            goto interpret_error;

      return p;

interpret_error:
      pqInternalNotice(&res->noticeHooks,
                               "could not interpret result from server: %s",
                               res->cmdStatus);
      return "";
}

/*
 * PQgetvalue:
 *    return the value of field 'field_num' of row 'tup_num'
 */
char *
PQgetvalue(const PGresult *res, int tup_num, int field_num)
{
      if (!check_tuple_field_number(res, tup_num, field_num))
            return NULL;
      return res->tuples[tup_num][field_num].value;
}

/* PQgetlength:
 *    returns the actual length of a field value in bytes.
 */
int
PQgetlength(const PGresult *res, int tup_num, int field_num)
{
      if (!check_tuple_field_number(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(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;
}

/* PQnparams:
 *    returns the number of input parameters of a prepared statement.
 */
int
PQnparams(const PGresult *res)
{
      if (!res)
            return 0;
      return res->numParameters;
}

/* PQparamtype:
 *    returns type Oid of the specified statement parameter.
 */
Oid
PQparamtype(const PGresult *res, int param_num)
{
      if (!check_param_number(res, param_num))
            return InvalidOid;
      if (res->paramDescs)
            return res->paramDescs[param_num].typid;
      else
            return InvalidOid;
}


/* 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)
{
      bool        barg;

      if (!conn || conn->status == CONNECTION_BAD)
            return -1;

      barg = (arg ? TRUE : FALSE);

      /* early out if the socket is already in the state requested */
      if (barg == 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 = barg;

      return 0;
}

/*
 * return the blocking status of the database connection
 *          TRUE == nonblocking, FALSE == blocking
 */
int
PQisnonblocking(const PGconn *conn)
{
      return pqIsnonblocking(conn);
}

/* libpq is thread-safe? */
int
PQisthreadsafe(void)
{
#ifdef ENABLE_THREAD_SAFETY
      return true;
#else
      return false;
#endif
}


/* try to force data out, really only useful for non-blocking users */
int
PQflush(PGconn *conn)
{
      return pqFlush(conn);
}


/*
 *          PQfreemem - safely frees memory allocated
 *
 * Needed mostly by Win32, unless multithreaded DLL (/MD in VC6)
 * Used for freeing memory from PQescapeByte()a/PQunescapeBytea()
 */
void
PQfreemem(void *ptr)
{
      free(ptr);
}

/*
 * PQfreeNotify - free's the memory associated with a PGnotify
 *
 * This function is here only for binary backward compatibility.
 * New code should use PQfreemem().  A macro will automatically map
 * calls to PQfreemem.  It should be removed in the future.  bjm 2003-03-24
 */

#undef PQfreeNotify
void        PQfreeNotify(PGnotify *notify);

void
PQfreeNotify(PGnotify *notify)
{
      PQfreemem(notify);
}


/*
 * Escaping arbitrary strings to get valid SQL literal strings.
 *
 * Replaces "'" with "''", and if not std_strings, replaces "\" with "\\".
 *
 * length is the length of the source string.  (Note: if a terminating NUL
 * is encountered sooner, PQescapeString stops short of "length"; the behavior
 * is thus rather like strncpy.)
 *
 * For safety the buffer at "to" must be at least 2*length + 1 bytes long.
 * A terminating NUL character is added to the output string, whether the
 * input is NUL-terminated or not.
 *
 * Returns the actual length of the output (not counting the terminating NUL).
 */
static size_t
PQescapeStringInternal(PGconn *conn,
                                 char *to, const char *from, size_t length,
                                 int *error,
                                 int encoding, bool std_strings)
{
      const char *source = from;
      char     *target = to;
      size_t            remaining = length;

      if (error)
            *error = 0;

      while (remaining > 0 && *source != '\0')
      {
            char        c = *source;
            int               len;
            int               i;

            /* Fast path for plain ASCII */
            if (!IS_HIGHBIT_SET(c))
            {
                  /* Apply quoting if needed */
                  if (SQL_STR_DOUBLE(c, !std_strings))
                        *target++ = c;
                  /* Copy the character */
                  *target++ = c;
                  source++;
                  remaining--;
                  continue;
            }

            /* Slow path for possible multibyte characters */
            len = pg_encoding_mblen(encoding, source);

            /* Copy the character */
            for (i = 0; i < len; i++)
            {
                  if (remaining == 0 || *source == '\0')
                        break;
                  *target++ = *source++;
                  remaining--;
            }

            /*
             * If we hit premature end of string (ie, incomplete multibyte
             * character), try to pad out to the correct length with spaces. We
             * may not be able to pad completely, but we will always be able to
             * insert at least one pad space (since we'd not have quoted a
             * multibyte character).  This should be enough to make a string that
             * the server will error out on.
             */
            if (i < len)
            {
                  if (error)
                        *error = 1;
                  if (conn)
                        printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("incomplete multibyte character\n"));
                  for (; i < len; i++)
                  {
                        if (((size_t) (target - to)) / 2 >= length)
                              break;
                        *target++ = ' ';
                  }
                  break;
            }
      }

      /* Write the terminating NUL character. */
      *target = '\0';

      return target - to;
}

size_t
PQescapeStringConn(PGconn *conn,
                           char *to, const char *from, size_t length,
                           int *error)
{
      if (!conn)
      {
            /* force empty-string result */
            *to = '\0';
            if (error)
                  *error = 1;
            return 0;
      }
      return PQescapeStringInternal(conn, to, from, length, error,
                                                  conn->client_encoding,
                                                  conn->std_strings);
}

size_t
PQescapeString(char *to, const char *from, size_t length)
{
      return PQescapeStringInternal(NULL, to, from, length, NULL,
                                                  static_client_encoding,
                                                  static_std_strings);
}

/*
 *          PQescapeBytea     - converts from binary string to the
 *          minimal encoding necessary to include the string in an SQL
 *          INSERT statement with a bytea type column as the target.
 *
 *          The following transformations are applied
 *          '\0' == ASCII  0 == \000
 *          '\'' == ASCII 39 == ''
 *          '\\' == ASCII 92 == \\
 *          anything < 0x20, or > 0x7e ---> \ooo
 *                                                          (where ooo is an octal expression)
 *          If not std_strings, all backslashes sent to the output are doubled.
 */
static unsigned char *
PQescapeByteaInternal(PGconn *conn,
                                const unsigned char *from, size_t from_length,
                                size_t *to_length, bool std_strings)
{
      const unsigned char *vp;
      unsigned char *rp;
      unsigned char *result;
      size_t            i;
      size_t            len;
      size_t            bslash_len = (std_strings ? 1 : 2);

      /*
       * empty string has 1 char ('\0')
       */
      len = 1;

      vp = from;
      for (i = from_length; i > 0; i--, vp++)
      {
            if (*vp < 0x20 || *vp > 0x7e)
                  len += bslash_len + 3;
            else if (*vp == '\'')
                  len += 2;
            else if (*vp == '\\')
                  len += bslash_len + bslash_len;
            else
                  len++;
      }

      *to_length = len;
      rp = result = (unsigned char *) malloc(len);
      if (rp == NULL)
      {
            if (conn)
                  printfPQExpBuffer(&conn->errorMessage,
                                            libpq_gettext("out of memory\n"));
            return NULL;
      }

      vp = from;
      for (i = from_length; i > 0; i--, vp++)
      {
            if (*vp < 0x20 || *vp > 0x7e)
            {
                  int               val = *vp;

                  if (!std_strings)
                        *rp++ = '\\';
                  *rp++ = '\\';
                  *rp++ = (val >> 6) + '0';
                  *rp++ = ((val >> 3) & 07) + '0';
                  *rp++ = (val & 07) + '0';
            }
            else if (*vp == '\'')
            {
                  *rp++ = '\'';
                  *rp++ = '\'';
            }
            else if (*vp == '\\')
            {
                  if (!std_strings)
                  {
                        *rp++ = '\\';
                        *rp++ = '\\';
                  }
                  *rp++ = '\\';
                  *rp++ = '\\';
            }
            else
                  *rp++ = *vp;
      }
      *rp = '\0';

      return result;
}

unsigned char *
PQescapeByteaConn(PGconn *conn,
                          const unsigned char *from, size_t from_length,
                          size_t *to_length)
{
      if (!conn)
            return NULL;
      return PQescapeByteaInternal(conn, from, from_length, to_length,
                                                 conn->std_strings);
}

unsigned char *
PQescapeBytea(const unsigned char *from, size_t from_length, size_t *to_length)
{
      return PQescapeByteaInternal(NULL, from, from_length, to_length,
                                                 static_std_strings);
}


#define ISFIRSTOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '3')
#define ISOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '7')
#define OCTVAL(CH) ((CH) - '0')

/*
 *          PQunescapeBytea - converts the null terminated string representation
 *          of a bytea, strtext, into binary, filling a buffer. It returns a
 *          pointer to the buffer (or NULL on error), and the size of the
 *          buffer in retbuflen. The pointer may subsequently be used as an
 *          argument to the function PQfreemem.
 *
 *          The following transformations are made:
 *          \\     == ASCII 92 == \
 *          \ooo == a byte whose value = ooo (ooo is an octal number)
 *          \x     == x (x is any character not matched by the above transformations)
 */
unsigned char *
PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
{
      size_t            strtextlen,
                        buflen;
      unsigned char *buffer,
                     *tmpbuf;
      size_t            i,
                        j;

      if (strtext == NULL)
            return NULL;

      strtextlen = strlen((const char *) strtext);

      /*
       * Length of input is max length of output, but add one to avoid
       * unportable malloc(0) if input is zero-length.
       */
      buffer = (unsigned char *) malloc(strtextlen + 1);
      if (buffer == NULL)
            return NULL;

      for (i = j = 0; i < strtextlen;)
      {
            switch (strtext[i])
            {
                  case '\\':
                        i++;
                        if (strtext[i] == '\\')
                              buffer[j++] = strtext[i++];
                        else
                        {
                              if ((ISFIRSTOCTDIGIT(strtext[i])) &&
                                    (ISOCTDIGIT(strtext[i + 1])) &&
                                    (ISOCTDIGIT(strtext[i + 2])))
                              {
                                    int byte;

                                    byte = OCTVAL(strtext[i++]);
                                    byte = (byte <<3) +OCTVAL(strtext[i++]);
                                    byte = (byte <<3) +OCTVAL(strtext[i++]);
                                    buffer[j++] = byte;
                              }
                        }

                        /*
                         * Note: if we see '\' followed by something that isn't a
                         * recognized escape sequence, we loop around having done
                         * nothing except advance i.  Therefore the something will be
                         * emitted as ordinary data on the next cycle. Corner case:
                         * '\' at end of string will just be discarded.
                         */
                        break;

                  default:
                        buffer[j++] = strtext[i++];
                        break;
            }
      }
      buflen = j;                         /* buflen is the length of the dequoted data */

      /* Shrink the buffer to be no larger than necessary */
      /* +1 avoids unportable behavior when buflen==0 */
      tmpbuf = realloc(buffer, buflen + 1);

      /* It would only be a very brain-dead realloc that could fail, but... */
      if (!tmpbuf)
      {
            free(buffer);
            return NULL;
      }

      *retbuflen = buflen;
      return tmpbuf;
}

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