/Users/deen/code/yugabyte-db/src/postgres/src/interfaces/libpq/fe-protocol3.c

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/*-------------------------------------------------------------------------
 *
 * fe-protocol3.c
 *    functions that are specific to frontend/backend protocol version 3
 *
 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/interfaces/libpq/fe-protocol3.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

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

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

#include "mb/pg_wchar.h"
#include "port/pg_bswap.h"

#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif
#endif


/*
 * This macro lists the backend message types that could be "long" (more
 * than a couple of kilobytes).
 */
#define VALID_LONG_MESSAGE_TYPE(id) \
  ((id) == 'T' || (id) == 'D' || (id) == 'd' || (id) == 'V' || \
   (id) == 'E' || (id) == 'N' || (id) == 'A')

#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))


static void handleSyncLoss(PGconn *conn, char id, int msgLength);
static int  getRowDescriptions(PGconn *conn, int msgLength);
static int  getParamDescriptions(PGconn *conn, int msgLength);
static int  getAnotherTuple(PGconn *conn, int msgLength);
static int  getParameterStatus(PGconn *conn);
static int  getNotify(PGconn *conn);
static int  getCopyStart(PGconn *conn, ExecStatusType copytype);
static int  getReadyForQuery(PGconn *conn);
static void reportErrorPosition(PQExpBuffer msg, const char *query,
          int loc, int encoding);
static int build_startup_packet(const PGconn *conn, char *packet,
           const PQEnvironmentOption *options);


/*
 * parseInput: if appropriate, parse input data from backend
 * until input is exhausted or a stopping state is reached.
 * Note that this function will NOT attempt to read more data from the backend.
 */
void
pqParseInput3(PGconn *conn)
{
  char    id;
  int     msgLength;
  int     avail;

  /*
   * Loop to parse successive complete messages available in the buffer.
   */
  for (;;)
  {
    /*
     * Try to read a message.  First get the type code and length. Return
     * if not enough data.
     */
    conn->inCursor = conn->inStart;
    if (pqGetc(&id, conn))
      return;
    if (pqGetInt(&msgLength, 4, conn))
      return;

    /*
     * Try to validate message type/length here.  A length less than 4 is
     * definitely broken.  Large lengths should only be believed for a few
     * message types.
     */
    if (msgLength < 4)
    {
      handleSyncLoss(conn, id, msgLength);
      return;
    }
    if (msgLength > 30000 && !0VALID_LONG_MESSAGE_TYPE0(id))
    {
      handleSyncLoss(conn, id, msgLength);
      return;
    }

    /*
     * Can't process if message body isn't all here yet.
     */
    msgLength -= 4;
    avail = conn->inEnd - conn->inCursor;
    if (avail < msgLength)
    {
      /*
       * Before returning, enlarge the input buffer if needed to hold
       * the whole message.  This is better than leaving it to
       * pqReadData because we can avoid multiple cycles of realloc()
       * when the message is large; also, we can implement a reasonable
       * recovery strategy if we are unable to make the buffer big
       * enough.
       */
      if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
                   conn))
      {
        /*
         * XXX add some better recovery code... plan is to skip over
         * the message using its length, then report an error. For the
         * moment, just treat this like loss of sync (which indeed it
         * might be!)
         */
        handleSyncLoss(conn, id, msgLength);
      }
      return;
    }

    /*
     * NOTIFY and NOTICE messages can happen in any state; always process
     * them right away.
     *
     * Most other messages should only be processed while in BUSY state.
     * (In particular, in READY state we hold off further parsing until
     * the application collects the current PGresult.)
     *
     * However, if the state is IDLE then we got trouble; we need to deal
     * with the unexpected message somehow.
     *
     * ParameterStatus ('S') messages are a special case: in IDLE state we
     * must process 'em (this case could happen if a new value was adopted
     * from config file due to SIGHUP), but otherwise we hold off until
     * BUSY state.
     */
    if (id == 'A')
    {
      if (getNotify(conn))
        return;
    }
    else if (id == 'N')
    {
      if (pqGetErrorNotice3(conn, false))
        return;
    }
    else if (conn->asyncStatus != PGASYNC_BUSY)
    {
      /* If not IDLE state, just wait ... */
      if (conn->asyncStatus != PGASYNC_IDLE)
        return;

      /*
       * Unexpected message in IDLE state; need to recover somehow.
       * ERROR messages are handled using the notice processor;
       * ParameterStatus is handled normally; anything else is just
       * dropped on the floor after displaying a suitable warning
       * notice.  (An ERROR is very possibly the backend telling us why
       * it is about to close the connection, so we don't want to just
       * discard it...)
       */
      if (id == 'E')
      {
        if (pqGetErrorNotice3(conn, false /* treat as notice */ ))
          return;
      }
      else if (id == 'S')
      {
        if (getParameterStatus(conn))
          return;
      }
      else
      {
        pqInternalNotice(&conn->noticeHooks,
                 "message type 0x%02x arrived from server while idle",
                 id);
        /* Discard the unexpected message */
        conn->inCursor += msgLength;
      }
    }
    else
    {
      /*
       * In BUSY state, we can process everything.
       */
      switch (id)
      {
        case 'C':   /* command complete */
          if (pqGets(&conn->workBuffer, conn))
            return;
          if (conn->result == NULL)
          {
            conn->result = PQmakeEmptyPGresult(conn,
                               PGRES_COMMAND_OK);
            if (!conn->result)
            {
              printfPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("out of memory"));
              pqSaveErrorResult(conn);
            }
          }
          if (conn->result)
            strlcpy(conn->result->cmdStatus, conn->workBuffer.data,
                CMDSTATUS_LEN);
          conn->asyncStatus = PGASYNC_READY;
          break;
        case 'E':   /* error return */
          if (pqGetErrorNotice3(conn, true))
            return;
          conn->asyncStatus = PGASYNC_READY;
          break;
        case 'Z':   /* backend is ready for new query */
          if (getReadyForQuery(conn))
            return;
          conn->asyncStatus = PGASYNC_IDLE;
          break;
        case 'I':   /* empty query */
          if (conn->result == NULL)
          {
            conn->result = PQmakeEmptyPGresult(conn,
                               PGRES_EMPTY_QUERY);
            if (!conn->result)
            {
              printfPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("out of memory"));
              pqSaveErrorResult(conn);
            }
          }
          conn->asyncStatus = PGASYNC_READY;
          break;
        case '1':   /* Parse Complete */
          /* If we're doing PQprepare, we're done; else ignore */
          if (conn->queryclass == PGQUERY_PREPARE)
          {
            if (conn->result == NULL)
            {
              conn->result = PQmakeEmptyPGresult(conn,
                                 PGRES_COMMAND_OK);
              if (!conn->result)
              {
                printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("out of memory"));
                pqSaveErrorResult(conn);
              }
            }
            conn->asyncStatus = PGASYNC_READY;
          }
          break;
        case '2':   /* Bind Complete */
        case '3':   /* Close Complete */
          /* Nothing to do for these message types */
          break;
        case 'S':   /* parameter status */
          if (getParameterStatus(conn))
            return;
          break;
        case 'K':   /* secret key data from the backend */

          /*
           * This is expected only during backend startup, but it's
           * just as easy to handle it as part of the main loop.
           * Save the data and continue processing.
           */
          if (pqGetInt(&(conn->be_pid), 4, conn))
            return;
          if (pqGetInt(&(conn->be_key), 4, conn))
            return;
          break;
        case 'T':   /* Row Description */
          if (conn->result != NULL &&
            conn->result->resultStatus == PGRES_FATAL_ERROR6)
          {
            /*
             * We've already choked for some reason.  Just discard
             * the data till we get to the end of the query.
             */
            conn->inCursor += msgLength;
          }
          else if (conn->result == NULL ||
               conn->queryclass == PGQUERY_DESCRIBE6)
          {
            /* First 'T' in a query sequence */
            if (getRowDescriptions(conn, msgLength))
              return;
            /* getRowDescriptions() moves inStart itself */
            continue;
          }
          else
          {
            /*
             * A new 'T' message is treated as the start of
             * another PGresult.  (It is not clear that this is
             * really possible with the current backend.) We stop
             * parsing until the application accepts the current
             * result.
             */
            conn->asyncStatus = PGASYNC_READY;
            return;
          }
          break;
        case 'n':   /* No Data */

          /*
           * NoData indicates that we will not be seeing a
           * RowDescription message because the statement or portal
           * inquired about doesn't return rows.
           *
           * If we're doing a Describe, we have to pass something
           * back to the client, so set up a COMMAND_OK result,
           * instead of TUPLES_OK.  Otherwise we can just ignore
           * this message.
           */
          if (conn->queryclass == PGQUERY_DESCRIBE)
          {
            if (conn->result == NULL)
            {
              conn->result = PQmakeEmptyPGresult(conn,
                                 PGRES_COMMAND_OK);
              if (!conn->result)
              {
                printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("out of memory"));
                pqSaveErrorResult(conn);
              }
            }
            conn->asyncStatus = PGASYNC_READY;
          }
          break;
        case 't':   /* Parameter Description */
          if (getParamDescriptions(conn, msgLength))
            return;
          /* getParamDescriptions() moves inStart itself */
          continue;
        case 'D':   /* Data Row */
          if (conn->result != NULL &&
            conn->result->resultStatus == PGRES_TUPLES_OK519k)
          {
            /* Read another tuple of a normal query response */
            if (getAnotherTuple(conn, msgLength))
              return;
            /* getAnotherTuple() moves inStart itself */
            continue;
          }
          else if (conn->result != NULL &&
               conn->result->resultStatus == PGRES_FATAL_ERROR0)
          {
            /*
             * We've already choked for some reason.  Just discard
             * tuples till we get to the end of the query.
             */
            conn->inCursor += msgLength;
          }
          else
          {
            /* Set up to report error at end of query */
            printfPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("server sent data (\"D\" message) without prior row description (\"T\" message)\n"));
            pqSaveErrorResult(conn);
            /* Discard the unexpected message */
            conn->inCursor += msgLength;
          }
          break;
        case 'G':   /* Start Copy In */
          if (getCopyStart(conn, PGRES_COPY_IN))
            return;
          conn->asyncStatus = PGASYNC_COPY_IN;
          break;
        case 'H':   /* Start Copy Out */
          if (getCopyStart(conn, PGRES_COPY_OUT))
            return;
          conn->asyncStatus = PGASYNC_COPY_OUT;
          conn->copy_already_done = 0;
          break;
        case 'W':   /* Start Copy Both */
          if (getCopyStart(conn, PGRES_COPY_BOTH))
            return;
          conn->asyncStatus = PGASYNC_COPY_BOTH;
          conn->copy_already_done = 0;
          break;
        case 'd':   /* Copy Data */

          /*
           * If we see Copy Data, just silently drop it.  This would
           * only occur if application exits COPY OUT mode too
           * early.
           */
          conn->inCursor += msgLength;
          break;
        case 'c':   /* Copy Done */

          /*
           * If we see Copy Done, just silently drop it.  This is
           * the normal case during PQendcopy.  We will keep
           * swallowing data, expecting to see command-complete for
           * the COPY command.
           */
          break;
        default:
          printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext(
                          "unexpected response from server; first received character was \"%c\"\n"),
                    id);
          /* build an error result holding the error message */
          pqSaveErrorResult(conn);
          /* not sure if we will see more, so go to ready state */
          conn->asyncStatus = PGASYNC_READY;
          /* Discard the unexpected message */
          conn->inCursor += msgLength;
          break;
      }         /* switch on protocol character */
    }
    /* Successfully consumed this message */
    if (conn->inCursor == conn->inStart + 5 + msgLength)
    {
      /* Normal case: parsing agrees with specified length */
      conn->inStart = conn->inCursor;
    }
    else
    {
      /* Trouble --- report it */
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("message contents do not agree with length in message type \"%c\"\n"),
                id);
      /* build an error result holding the error message */
      pqSaveErrorResult(conn);
      conn->asyncStatus = PGASYNC_READY;
      /* trust the specified message length as what to skip */
      conn->inStart += 5 + msgLength;
    }
  }
}

/*
 * handleSyncLoss: clean up after loss of message-boundary sync
 *
 * There isn't really a lot we can do here except abandon the connection.
 */
static void
handleSyncLoss(PGconn *conn, char id, int msgLength)
{
  printfPQExpBuffer(&conn->errorMessage,
            libpq_gettext(
                  "lost synchronization with server: got message type \"%c\", length %d\n"),
            id, msgLength);
  /* build an error result holding the error message */
  pqSaveErrorResult(conn);
  conn->asyncStatus = PGASYNC_READY;  /* drop out of GetResult wait loop */
  /* flush input data since we're giving up on processing it */
  pqDropConnection(conn, true);
  conn->status = CONNECTION_BAD;  /* No more connection to backend */
}

/*
 * parseInput subroutine to read a 'T' (row descriptions) message.
 * We'll build a new PGresult structure (unless called for a Describe
 * command for a prepared statement) containing the attribute data.
 * Returns: 0 if processed message successfully, EOF to suspend parsing
 * (the latter case is not actually used currently).
 * In the former case, conn->inStart has been advanced past the message.
 */
static int
getRowDescriptions(PGconn *conn, int msgLength)
{
  PGresult   *result;
  int     nfields;
  const char *errmsg;
  int     i;

  /*
   * When doing Describe for a prepared statement, there'll already be a
   * PGresult created by getParamDescriptions, and we should fill data into
   * that.  Otherwise, create a new, empty PGresult.
   */
  if (conn->queryclass == PGQUERY_DESCRIBE)
  {
    if (conn->result)
      result = conn->result;
    else
      result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK);
  }
  else
    result = PQmakeEmptyPGresult(conn, PGRES_TUPLES_OK);
  if (!result)
  {
    errmsg = NULL;      /* means "out of memory", see below */
    goto advance_and_error;
  }

  /* parseInput already read the 'T' label and message length. */
  /* the next two bytes are the number of fields */
  if (pqGetInt(&(result->numAttributes), 2, conn))
  {
    /* We should not run out of data here, so complain */
    errmsg = libpq_gettext("insufficient data in \"T\" message");
    goto advance_and_error;
  }
  nfields = result->numAttributes;

  /* allocate space for the attribute descriptors */
  if (nfields > 0)
  {
    result->attDescs = (PGresAttDesc *)
      pqResultAlloc(result, nfields * sizeof(PGresAttDesc), true);
    if (!result->attDescs)
    {
      errmsg = NULL;    /* means "out of memory", see below */
      goto advance_and_error;
    }
    MemSet(result->attDescs, 0, nfields * sizeof(PGresAttDesc));
  }

  /* result->binary is true only if ALL columns are binary */
  result->binary = (nfields > 0) ? 1 : 00;

  /* get type info */
  for (i = 0; i < nfields; i++24.6k)
  {
    int     tableid;
    int     columnid;
    int     typid;
    int     typlen;
    int     atttypmod;
    int     format;

    if (pqGets(&conn->workBuffer, conn) ||
      pqGetInt(&tableid, 4, conn) ||
      pqGetInt(&columnid, 2, conn) ||
      pqGetInt(&typid, 4, conn) ||
      pqGetInt(&typlen, 2, conn) ||
      pqGetInt(&atttypmod, 4, conn) ||
      pqGetInt(&format, 2, conn))
    {
      /* We should not run out of data here, so complain */
      errmsg = libpq_gettext("insufficient data in \"T\" message");
      goto advance_and_error;
    }

    /*
     * Since pqGetInt treats 2-byte integers as unsigned, we need to
     * coerce these results to signed form.
     */
    columnid = (int) ((int16) columnid);
    typlen = (int) ((int16) typlen);
    format = (int) ((int16) format);

    result->attDescs[i].name = pqResultStrdup(result,
                          conn->workBuffer.data);
    if (!result->attDescs[i].name)
    {
      errmsg = NULL;    /* means "out of memory", see below */
      goto advance_and_error;
    }
    result->attDescs[i].tableid = tableid;
    result->attDescs[i].columnid = columnid;
    result->attDescs[i].format = format;
    result->attDescs[i].typid = typid;
    result->attDescs[i].typlen = typlen;
    result->attDescs[i].atttypmod = atttypmod;

    if (format != 1)
      result->binary = 0;
  }

  /* Sanity check that we absorbed all the data */
  if (conn->inCursor != conn->inStart + 5 + msgLength)
  {
    errmsg = libpq_gettext("extraneous data in \"T\" message");
    goto advance_and_error;
  }

  /* Success! */
  conn->result = result;

  /* Advance inStart to show that the "T" message has been processed. */
  conn->inStart = conn->inCursor;

  /*
   * If we're doing a Describe, we're done, and ready to pass the result
   * back to the client.
   */
  if (conn->queryclass == PGQUERY_DESCRIBE)
  {
    conn->asyncStatus = PGASYNC_READY;
    return 0;
  }

  /*
   * We could perform additional setup for the new result set here, but for
   * now there's nothing else to do.
   */

  /* And we're done. */
  return 0;

advance_and_error:
  /* Discard unsaved result, if any */
  if (result && result != conn->result)
    PQclear(result);

  /* Discard the failed message by pretending we read it */
  conn->inStart += 5 + msgLength;

  /*
   * Replace partially constructed result with an error result. First
   * discard the old result to try to win back some memory.
   */
  pqClearAsyncResult(conn);

  /*
   * If preceding code didn't provide an error message, assume "out of
   * memory" was meant.  The advantage of having this special case is that
   * freeing the old result first greatly improves the odds that gettext()
   * will succeed in providing a translation.
   */
  if (!errmsg)
    errmsg = libpq_gettext("out of memory for query result");

  printfPQExpBuffer(&conn->errorMessage, "%s\n", errmsg);
  pqSaveErrorResult(conn);

  /*
   * Return zero to allow input parsing to continue.  Subsequent "D"
   * messages will be ignored until we get to end of data, since an error
   * result is already set up.
   */
  return 0;
}

/*
 * parseInput subroutine to read a 't' (ParameterDescription) message.
 * We'll build a new PGresult structure containing the parameter data.
 * Returns: 0 if completed message, EOF if not enough data yet.
 * In the former case, conn->inStart has been advanced past the message.
 *
 * Note that if we run out of data, we have to release the partially
 * constructed PGresult, and rebuild it again next time.  Fortunately,
 * that shouldn't happen often, since 't' messages usually fit in a packet.
 */
static int
getParamDescriptions(PGconn *conn, int msgLength)
{
  PGresult   *result;
  const char *errmsg = NULL;  /* means "out of memory", see below */
  int     nparams;
  int     i;

  result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK);
  if (!result)
    goto advance_and_error;

  /* parseInput already read the 't' label and message length. */
  /* the next two bytes are the number of parameters */
  if (pqGetInt(&(result->numParameters), 2, conn))
    goto not_enough_data;
  nparams = result->numParameters;

  /* allocate space for the parameter descriptors */
  if (nparams > 0)
  {
    result->paramDescs = (PGresParamDesc *)
      pqResultAlloc(result, nparams * sizeof(PGresParamDesc), true);
    if (!result->paramDescs)
      goto advance_and_error;
    MemSet(result->paramDescs, 0, nparams * sizeof(PGresParamDesc));
  }

  /* get parameter info */
  for (i = 0; i < nparams; i++)
  {
    int     typid;

    if (pqGetInt(&typid, 4, conn))
      goto not_enough_data;
    result->paramDescs[i].typid = typid;
  }

  /* Sanity check that we absorbed all the data */
  if (conn->inCursor != conn->inStart + 5 + msgLength)
  {
    errmsg = libpq_gettext("extraneous data in \"t\" message");
    goto advance_and_error;
  }

  /* Success! */
  conn->result = result;

  /* Advance inStart to show that the "t" message has been processed. */
  conn->inStart = conn->inCursor;

  return 0;

not_enough_data:
  PQclear(result);
  return EOF;

advance_and_error:
  /* Discard unsaved result, if any */
  if (result && result != conn->result)
    PQclear(result);

  /* Discard the failed message by pretending we read it */
  conn->inStart += 5 + msgLength;

  /*
   * Replace partially constructed result with an error result. First
   * discard the old result to try to win back some memory.
   */
  pqClearAsyncResult(conn);

  /*
   * If preceding code didn't provide an error message, assume "out of
   * memory" was meant.  The advantage of having this special case is that
   * freeing the old result first greatly improves the odds that gettext()
   * will succeed in providing a translation.
   */
  if (!errmsg)
    errmsg = libpq_gettext("out of memory");
  printfPQExpBuffer(&conn->errorMessage, "%s\n", errmsg);
  pqSaveErrorResult(conn);

  /*
   * Return zero to allow input parsing to continue.  Essentially, we've
   * replaced the COMMAND_OK result with an error result, but since this
   * doesn't affect the protocol state, it's fine.
   */
  return 0;
}

/*
 * parseInput subroutine to read a 'D' (row data) message.
 * We fill rowbuf with column pointers and then call the row processor.
 * Returns: 0 if processed message successfully, EOF to suspend parsing
 * (the latter case is not actually used currently).
 * In the former case, conn->inStart has been advanced past the message.
 */
static int
getAnotherTuple(PGconn *conn, int msgLength)
{
  PGresult   *result = conn->result;
  int     nfields = result->numAttributes;
  const char *errmsg;
  PGdataValue *rowbuf;
  int     tupnfields;   /* # fields from tuple */
  int     vlen;     /* length of the current field value */
  int     i;

  /* Get the field count and make sure it's what we expect */
  if (pqGetInt(&tupnfields, 2, conn))
  {
    /* We should not run out of data here, so complain */
    errmsg = libpq_gettext("insufficient data in \"D\" message");
    goto advance_and_error;
  }

  if (tupnfields != nfields)
  {
    errmsg = libpq_gettext("unexpected field count in \"D\" message");
    goto advance_and_error;
  }

  /* Resize row buffer if needed */
  rowbuf = conn->rowBuf;
  if (nfields > conn->rowBufLen)
  {
    rowbuf = (PGdataValue *) realloc(rowbuf,
                     nfields * sizeof(PGdataValue));
    if (!rowbuf)
    {
      errmsg = NULL;    /* means "out of memory", see below */
      goto advance_and_error;
    }
    conn->rowBuf = rowbuf;
    conn->rowBufLen = nfields;
  }

  /* Scan the fields */
  for (i = 0; 519ki < nfields; i++777k)
  {
    /* get the value length */
    if (pqGetInt(&vlen, 4, conn))
    {
      /* We should not run out of data here, so complain */
      errmsg = libpq_gettext("insufficient data in \"D\" message");
      goto advance_and_error;
    }
    rowbuf[i].len = vlen;

    /*
     * rowbuf[i].value always points to the next address in the data
     * buffer even if the value is NULL.  This allows row processors to
     * estimate data sizes more easily.
     */
    rowbuf[i].value = conn->inBuffer + conn->inCursor;

    /* Skip over the data value */
    if (vlen > 0)
    {
      if (pqSkipnchar(vlen, conn))
      {
        /* We should not run out of data here, so complain */
        errmsg = libpq_gettext("insufficient data in \"D\" message");
        goto advance_and_error;
      }
    }
  }

  /* Sanity check that we absorbed all the data */
  if (conn->inCursor != conn->inStart + 5 + msgLength)
  {
    errmsg = libpq_gettext("extraneous data in \"D\" message");
    goto advance_and_error;
  }

  /* Advance inStart to show that the "D" message has been processed. */
  conn->inStart = conn->inCursor;

  /* Process the collected row */
  errmsg = NULL;
  if (pqRowProcessor(conn, &errmsg))
    return 0;        /* normal, successful exit */

  goto set_error_result;    /* pqRowProcessor failed, report it */

advance_and_error:
  /* Discard the failed message by pretending we read it */
  conn->inStart += 5 + msgLength;

set_error_result:

  /*
   * Replace partially constructed result with an error result. First
   * discard the old result to try to win back some memory.
   */
  pqClearAsyncResult(conn);

  /*
   * If preceding code didn't provide an error message, assume "out of
   * memory" was meant.  The advantage of having this special case is that
   * freeing the old result first greatly improves the odds that gettext()
   * will succeed in providing a translation.
   */
  if (!errmsg)
    errmsg = libpq_gettext("out of memory for query result");

  printfPQExpBuffer(&conn->errorMessage, "%s\n", errmsg);
  pqSaveErrorResult(conn);

  /*
   * Return zero to allow input parsing to continue.  Subsequent "D"
   * messages will be ignored until we get to end of data, since an error
   * result is already set up.
   */
  return 0;
}


/*
 * Attempt to read an Error or Notice response message.
 * This is possible in several places, so we break it out as a subroutine.
 * Entry: 'E' or 'N' message type and length have already been consumed.
 * Exit: returns 0 if successfully consumed message.
 *     returns EOF if not enough data.
 */
int
pqGetErrorNotice3(PGconn *conn, bool isError)
{
  PGresult   *res = NULL;
  bool    have_position = false;
  PQExpBufferData workBuf;
  char    id;

  /*
   * If this is an error message, pre-emptively clear any incomplete query
   * result we may have.  We'd just throw it away below anyway, and
   * releasing it before collecting the error might avoid out-of-memory.
   */
  if (isError)
    pqClearAsyncResult(conn);

  /*
   * Since the fields might be pretty long, we create a temporary
   * PQExpBuffer rather than using conn->workBuffer.  workBuffer is intended
   * for stuff that is expected to be short.  We shouldn't use
   * conn->errorMessage either, since this might be only a notice.
   */
  initPQExpBuffer(&workBuf);

  /*
   * Make a PGresult to hold the accumulated fields.  We temporarily lie
   * about the result status, so that PQmakeEmptyPGresult doesn't uselessly
   * copy conn->errorMessage.
   *
   * NB: This allocation can fail, if you run out of memory. The rest of the
   * function handles that gracefully, and we still try to set the error
   * message as the connection's error message.
   */
  res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY);
  if (res)
    res->resultStatus = isError ? PGRES_FATAL_ERROR5.60k : PGRES_NONFATAL_ERROR210;

  /*
   * Read the fields and save into res.
   *
   * While at it, save the SQLSTATE in conn->last_sqlstate, and note whether
   * we saw a PG_DIAG_STATEMENT_POSITION field.
   */
  for (;;)
  {
    if (pqGetc(&id, conn))
      goto fail;
    if (id == '\0')
      break;        /* terminator found */
    if (pqGets(&workBuf, conn))
      goto fail;
    pqSaveMessageField(res, id, workBuf.data);
    if (id == PG_DIAG_SQLSTATE)
      strlcpy(conn->last_sqlstate, workBuf.data,
          sizeof(conn->last_sqlstate));
    else if (id == PG_DIAG_STATEMENT_POSITION)
      have_position = true;
  }

  /*
   * Save the active query text, if any, into res as well; but only if we
   * might need it for an error cursor display, which is only true if there
   * is a PG_DIAG_STATEMENT_POSITION field.
   */
  if (have_position && conn->last_query257 && res257)
    res->errQuery = pqResultStrdup(res, conn->last_query);

  /*
   * Now build the "overall" error message for PQresultErrorMessage.
   */
  resetPQExpBuffer(&workBuf);
  pqBuildErrorMessage3(&workBuf, res, conn->verbosity, conn->show_context);

  /*
   * Either save error as current async result, or just emit the notice.
   */
  if (isError)
  {
    if (res)
      res->errMsg = pqResultStrdup(res, workBuf.data);
    pqClearAsyncResult(conn); /* redundant, but be safe */
    conn->result = res;
    if (PQExpBufferDataBroken(workBuf))
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("out of memory"));
    else
      appendPQExpBufferStr(&conn->errorMessage, workBuf.data);
  }
  else
  {
    /* if we couldn't allocate the result set, just discard the NOTICE */
    if (res)
    {
      /* We can cheat a little here and not copy the message. */
      res->errMsg = workBuf.data;
      if (res->noticeHooks.noticeRec != NULL)
        res->noticeHooks.noticeRec(res->noticeHooks.noticeRecArg, res);
      PQclear(res);
    }
  }

  termPQExpBuffer(&workBuf);
  return 0;

fail:
  PQclear(res);
  termPQExpBuffer(&workBuf);
  return EOF;
}

/*
 * Construct an error message from the fields in the given PGresult,
 * appending it to the contents of "msg".
 */
void
pqBuildErrorMessage3(PQExpBuffer msg, const PGresult *res,
           PGVerbosity verbosity, PGContextVisibility show_context)
{
  const char *val;
  const char *querytext = NULL;
  int     querypos = 0;

  /* If we couldn't allocate a PGresult, just say "out of memory" */
  if (res == NULL)
  {
    appendPQExpBuffer(msg, libpq_gettext("out of memory\n"));
    return;
  }

  /*
   * If we don't have any broken-down fields, just return the base message.
   * This mainly applies if we're given a libpq-generated error result.
   */
  if (res->errFields == NULL)
  {
    if (res->errMsg && res->errMsg[0])
      appendPQExpBufferStr(msg, res->errMsg);
    else
      appendPQExpBuffer(msg, libpq_gettext("no error message available\n"));
    return;
  }

  /* Else build error message from relevant fields */
  val = PQresultErrorField(res, PG_DIAG_SEVERITY);
  if (val)
    appendPQExpBuffer(msg, "%s:  ", val);
  if (verbosity == PQERRORS_VERBOSE)
  {
    val = PQresultErrorField(res, PG_DIAG_SQLSTATE);
    if (val)
      appendPQExpBuffer(msg, "%s: ", val);
  }
  val = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
  if (val)
    appendPQExpBufferStr(msg, val);
  val = PQresultErrorField(res, PG_DIAG_STATEMENT_POSITION);
  if (val)
  {
    if (verbosity != PQERRORS_TERSE && res->errQuery != NULL)
    {
      /* emit position as a syntax cursor display */
      querytext = res->errQuery;
      querypos = atoi(val);
    }
    else
    {
      /* emit position as text addition to primary message */
      /* translator: %s represents a digit string */
      appendPQExpBuffer(msg, libpq_gettext(" at character %s"),
                val);
    }
  }
  else
  {
    val = PQresultErrorField(res, PG_DIAG_INTERNAL_POSITION);
    if (val)
    {
      querytext = PQresultErrorField(res, PG_DIAG_INTERNAL_QUERY);
      if (verbosity != PQERRORS_TERSE && querytext != NULL)
      {
        /* emit position as a syntax cursor display */
        querypos = atoi(val);
      }
      else
      {
        /* emit position as text addition to primary message */
        /* translator: %s represents a digit string */
        appendPQExpBuffer(msg, libpq_gettext(" at character %s"),
                  val);
      }
    }
  }
  appendPQExpBufferChar(msg, '\n');
  if (verbosity != PQERRORS_TERSE)
  {
    if (querytext && querypos > 0257)
      reportErrorPosition(msg, querytext, querypos,
                res->client_encoding);
    val = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
    if (val)
      appendPQExpBuffer(msg, libpq_gettext("DETAIL:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
    if (val)
      appendPQExpBuffer(msg, libpq_gettext("HINT:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_INTERNAL_QUERY);
    if (val)
      appendPQExpBuffer(msg, libpq_gettext("QUERY:  %s\n"), val);
    if (show_context == PQSHOW_CONTEXT_ALWAYS ||
      (show_context == PQSHOW_CONTEXT_ERRORS &&
       res->resultStatus == PGRES_FATAL_ERROR))
    {
      val = PQresultErrorField(res, PG_DIAG_CONTEXT);
      if (val)
        appendPQExpBuffer(msg, libpq_gettext("CONTEXT:  %s\n"),
                  val);
    }
  }
  if (verbosity == PQERRORS_VERBOSE)
  {
    val = PQresultErrorField(res, PG_DIAG_SCHEMA_NAME);
    if (val)
      appendPQExpBuffer(msg,
                libpq_gettext("SCHEMA NAME:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_TABLE_NAME);
    if (val)
      appendPQExpBuffer(msg,
                libpq_gettext("TABLE NAME:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_COLUMN_NAME);
    if (val)
      appendPQExpBuffer(msg,
                libpq_gettext("COLUMN NAME:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_DATATYPE_NAME);
    if (val)
      appendPQExpBuffer(msg,
                libpq_gettext("DATATYPE NAME:  %s\n"), val);
    val = PQresultErrorField(res, PG_DIAG_CONSTRAINT_NAME);
    if (val)
      appendPQExpBuffer(msg,
                libpq_gettext("CONSTRAINT NAME:  %s\n"), val);
  }
  if (verbosity == PQERRORS_VERBOSE)
  {
    const char *valf;
    const char *vall;

    valf = PQresultErrorField(res, PG_DIAG_SOURCE_FILE);
    vall = PQresultErrorField(res, PG_DIAG_SOURCE_LINE);
    val = PQresultErrorField(res, PG_DIAG_SOURCE_FUNCTION);
    if (val || valf || vall)
    {
      appendPQExpBufferStr(msg, libpq_gettext("LOCATION:  "));
      if (val)
        appendPQExpBuffer(msg, libpq_gettext("%s, "), val);
      if (valf && vall) /* unlikely we'd have just one */
        appendPQExpBuffer(msg, libpq_gettext("%s:%s"),
                  valf, vall);
      appendPQExpBufferChar(msg, '\n');
    }
  }
}

/*
 * Add an error-location display to the error message under construction.
 *
 * The cursor location is measured in logical characters; the query string
 * is presumed to be in the specified encoding.
 */
static void
reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding)
{
#define DISPLAY_SIZE  60    /* screen width limit, in screen cols */
#define MIN_RIGHT_CUT 1014    /* try to keep this far away from EOL */

  char     *wquery;
  int     slen,
        cno,
        i,
         *qidx,
         *scridx,
        qoffset,
        scroffset,
        ibeg,
        iend,
        loc_line;
  bool    mb_encoding,
        beg_trunc,
        end_trunc;

  /* Convert loc from 1-based to 0-based; no-op if out of range */
  loc--;
  if (loc < 0)
    return;

  /* Need a writable copy of the query */
  wquery = strdup(query);
  if (wquery == NULL)
    return;         /* fail silently if out of memory */

  /*
   * Each character might occupy multiple physical bytes in the string, and
   * in some Far Eastern character sets it might take more than one screen
   * column as well.  We compute the starting byte offset and starting
   * screen column of each logical character, and store these in qidx[] and
   * scridx[] respectively.
   */

  /* we need a safe allocation size... */
  slen = strlen(wquery) + 1;

  qidx = (int *) malloc(slen * sizeof(int));
  if (qidx == NULL)
  {
    free(wquery);
    return;
  }
  scridx = (int *) malloc(slen * sizeof(int));
  if (scridx == NULL)
  {
    free(qidx);
    free(wquery);
    return;
  }

  /* We can optimize a bit if it's a single-byte encoding */
  mb_encoding = (pg_encoding_max_length(encoding) != 1);

  /*
   * Within the scanning loop, cno is the current character's logical
   * number, qoffset is its offset in wquery, and scroffset is its starting
   * logical screen column (all indexed from 0).  "loc" is the logical
   * character number of the error location.  We scan to determine loc_line
   * (the 1-based line number containing loc) and ibeg/iend (first character
   * number and last+1 character number of the line containing loc). Note
   * that qidx[] and scridx[] are filled only as far as iend.
   */
  qoffset = 0;
  scroffset = 0;
  loc_line = 1;
  ibeg = 0;
  iend = -1;          /* -1 means not set yet */

  for (cno = 0; wquery[qoffset] != '\0'; cno++10.9k)
  {
    char    ch = wquery[qoffset];

    qidx[cno] = qoffset;
    scridx[cno] = scroffset;

    /*
     * Replace tabs with spaces in the writable copy.  (Later we might
     * want to think about coping with their variable screen width, but
     * not today.)
     */
    if (ch == '\t')
      wquery[qoffset] = ' ';

    /*
     * If end-of-line, count lines and mark positions. Each \r or \n
     * counts as a line except when \r \n appear together.
     */
    else if (ch == '\r' || ch == '\n')
    {
      if (cno < loc)
      {
        if (ch == '\r' ||
          cno == 0 ||
          wquery[qidx[cno - 1]] != '\r')
          loc_line++;
        /* extract beginning = last line start before loc. */
        ibeg = cno + 1;
      }
      else
      {
        /* set extract end. */
        iend = cno;
        /* done scanning. */
        break;
      }
    }

    /* Advance */
    if (mb_encoding)
    {
      int     w;

      w = pg_encoding_dsplen(encoding, &wquery[qoffset]);
      /* treat any non-tab control chars as width 1 */
      if (w <= 0)
        w = 1;
      scroffset += w;
      qoffset += PQmblenBounded(&wquery[qoffset], encoding);
    }
    else
    {
      /* We assume wide chars only exist in multibyte encodings */
      scroffset++;
      qoffset++;
    }
  }
  /* Fix up if we didn't find an end-of-line after loc */
  if (iend < 0)
  {
    iend = cno;       /* query length in chars, +1 */
    qidx[iend] = qoffset;
    scridx[iend] = scroffset;
  }

  /* Print only if loc is within computed query length */
  if (loc <= cno)
  {
    /* If the line extracted is too long, we truncate it. */
    beg_trunc = false;
    end_trunc = false;
    if (scridx[iend] - scridx[ibeg] > DISPLAY_SIZE)
    {
      /*
       * We first truncate right if it is enough.  This code might be
       * off a space or so on enforcing MIN_RIGHT_CUT if there's a wide
       * character right there, but that should be okay.
       */
      if (scridx[ibeg] + DISPLAY_SIZE >= scridx[loc] + MIN_RIGHT_CUT)
      {
        while (scridx[iend] - scridx[ibeg] > DISPLAY_SIZE)
          iend--;
        end_trunc = true;
      }
      else
      {
        /* Truncate right if not too close to loc. */
        while (scridx[loc] + MIN_RIGHT_CUT < scridx[iend])
        {
          iend--;
          end_trunc = true;
        }

        /* Truncate left if still too long. */
        while (scridx[iend] - scridx[ibeg] > DISPLAY_SIZE)
        {
          ibeg++;
          beg_trunc = true;
        }
      }
    }

    /* truncate working copy at desired endpoint */
    wquery[qidx[iend]] = '\0';

    /* Begin building the finished message. */
    i = msg->len;
    appendPQExpBuffer(msg, libpq_gettext("LINE %d: "), loc_line);
    if (beg_trunc)
      appendPQExpBufferStr(msg, "...");

    /*
     * While we have the prefix in the msg buffer, compute its screen
     * width.
     */
    scroffset = 0;
    for (; i < msg->len; i += 2.06kPQmblenBounded2.06k(&msg->data[i], encoding))
    {
      int     w = pg_encoding_dsplen(encoding, &msg->data[i]);

      if (w <= 0)
        w = 1;
      scroffset += w;
    }

    /* Finish up the LINE message line. */
    appendPQExpBufferStr(msg, &wquery[qidx[ibeg]]);
    if (end_trunc)
      appendPQExpBufferStr(msg, "...");
    appendPQExpBufferChar(msg, '\n');

    /* Now emit the cursor marker line. */
    scroffset += scridx[loc] - scridx[ibeg];
    for (i = 0; i < scroffset; i++5.75k)
      appendPQExpBufferChar(msg, ' ');
    appendPQExpBufferChar(msg, '^');
    appendPQExpBufferChar(msg, '\n');
  }

  /* Clean up. */
  free(scridx);
  free(qidx);
  free(wquery);
}


/*
 * Attempt to read a ParameterStatus message.
 * This is possible in several places, so we break it out as a subroutine.
 * Entry: 'S' message type and length have already been consumed.
 * Exit: returns 0 if successfully consumed message.
 *     returns EOF if not enough data.
 */
static int
getParameterStatus(PGconn *conn)
{
  PQExpBufferData valueBuf;

  /* Get the parameter name */
  if (pqGets(&conn->workBuffer, conn))
    return EOF;
  /* Get the parameter value (could be large) */
  initPQExpBuffer(&valueBuf);
  if (pqGets(&valueBuf, conn))
  {
    termPQExpBuffer(&valueBuf);
    return EOF;
  }
  /* And save it */
  pqSaveParameterStatus(conn, conn->workBuffer.data, valueBuf.data);
  termPQExpBuffer(&valueBuf);
  return 0;
}


/*
 * Attempt to read a Notify response message.
 * This is possible in several places, so we break it out as a subroutine.
 * Entry: 'A' message type and length have already been consumed.
 * Exit: returns 0 if successfully consumed Notify message.
 *     returns EOF if not enough data.
 */
static int
getNotify(PGconn *conn)
{
  int     be_pid;
  char     *svname;
  int     nmlen;
  int     extralen;
  PGnotify   *newNotify;

  if (pqGetInt(&be_pid, 4, conn))
    return EOF;
  if (pqGets(&conn->workBuffer, conn))
    return EOF;
  /* must save name while getting extra string */
  svname = strdup(conn->workBuffer.data);
  if (!svname)
    return EOF;
  if (pqGets(&conn->workBuffer, conn))
  {
    free(svname);
    return EOF;
  }

  /*
   * Store the strings right after the PQnotify structure so it can all be
   * freed at once.  We don't use NAMEDATALEN because we don't want to tie
   * this interface to a specific server name length.
   */
  nmlen = strlen(svname);
  extralen = strlen(conn->workBuffer.data);
  newNotify = (PGnotify *) malloc(sizeof(PGnotify) + nmlen + extralen + 2);
  if (newNotify)
  {
    newNotify->relname = (char *) newNotify + sizeof(PGnotify);
    strcpy(newNotify->relname, svname);
    newNotify->extra = newNotify->relname + nmlen + 1;
    strcpy(newNotify->extra, conn->workBuffer.data);
    newNotify->be_pid = be_pid;
    newNotify->next = NULL;
    if (conn->notifyTail)
      conn->notifyTail->next = newNotify;
    else
      conn->notifyHead = newNotify;
    conn->notifyTail = newNotify;
  }

  free(svname);
  return 0;
}

/*
 * getCopyStart - process CopyInResponse, CopyOutResponse or
 * CopyBothResponse message
 *
 * parseInput already read the message type and length.
 */
static int
getCopyStart(PGconn *conn, ExecStatusType copytype)
{
  PGresult   *result;
  int     nfields;
  int     i;

  result = PQmakeEmptyPGresult(conn, copytype);
  if (!result)
    goto failure;

  if (pqGetc(&conn->copy_is_binary, conn))
    goto failure;
  result->binary = conn->copy_is_binary;
  /* the next two bytes are the number of fields  */
  if (pqGetInt(&(result->numAttributes), 2, conn))
    goto failure;
  nfields = result->numAttributes;

  /* allocate space for the attribute descriptors */
  if (nfields > 0)
  {
    result->attDescs = (PGresAttDesc *)
      pqResultAlloc(result, nfields * sizeof(PGresAttDesc), true);
    if (!result->attDescs)
      goto failure;
    MemSet(result->attDescs, 0, nfields * sizeof(PGresAttDesc));
  }

  for (i = 0; 36i < nfields; i++126)
  {
    int     format;

    if (pqGetInt(&format, 2, conn))
      goto failure;

    /*
     * Since pqGetInt treats 2-byte integers as unsigned, we need to
     * coerce these results to signed form.
     */
    format = (int) ((int16) format);
    result->attDescs[i].format = format;
  }

  /* Success! */
  conn->result = result;
  return 0;

failure:
  PQclear(result);
  return EOF;
}

/*
 * getReadyForQuery - process ReadyForQuery message
 */
static int
getReadyForQuery(PGconn *conn)
{
  char    xact_status;

  if (pqGetc(&xact_status, conn))
    return EOF;
  switch (xact_status)
  {
    case 'I':
      conn->xactStatus = PQTRANS_IDLE;
      break;
    case 'T':
      conn->xactStatus = PQTRANS_INTRANS;
      break;
    case 'E':
      conn->xactStatus = PQTRANS_INERROR;
      break;
    default:
      conn->xactStatus = PQTRANS_UNKNOWN;
      break;
  }

  return 0;
}

/*
 * getCopyDataMessage - fetch next CopyData message, process async messages
 *
 * Returns length word of CopyData message (> 0), or 0 if no complete
 * message available, -1 if end of copy, -2 if error.
 */
static int
getCopyDataMessage(PGconn *conn)
{
  char    id;
  int     msgLength;
  int     avail;

  for (;;)
  {
    /*
     * Do we have the next input message?  To make life simpler for async
     * callers, we keep returning 0 until the next message is fully
     * available, even if it is not Copy Data.
     */
    conn->inCursor = conn->inStart;
    if (pqGetc(&id, conn))
      return 0;
    if (pqGetInt(&msgLength, 4, conn))
      return 0;
    if (msgLength < 4)
    {
      handleSyncLoss(conn, id, msgLength);
      return -2;
    }
    avail = conn->inEnd - conn->inCursor;
    if (avail < msgLength - 4)
    {
      /*
       * Before returning, enlarge the input buffer if needed to hold
       * the whole message.  See notes in parseInput.
       */
      if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength - 4,
                   conn))
      {
        /*
         * XXX add some better recovery code... plan is to skip over
         * the message using its length, then report an error. For the
         * moment, just treat this like loss of sync (which indeed it
         * might be!)
         */
        handleSyncLoss(conn, id, msgLength);
        return -2;
      }
      return 0;
    }

    /*
     * If it's a legitimate async message type, process it.  (NOTIFY
     * messages are not currently possible here, but we handle them for
     * completeness.)  Otherwise, if it's anything except Copy Data,
     * report end-of-copy.
     */
    switch (id)
    {
      case 'A':     /* NOTIFY */
        if (getNotify(conn))
          return 0;
        break;
      case 'N':     /* NOTICE */
        if (pqGetErrorNotice3(conn, false))
          return 0;
        break;
      case 'S':     /* ParameterStatus */
        if (getParameterStatus(conn))
          return 0;
        break;
      case 'd':     /* Copy Data, pass it back to caller */
        return msgLength;
      case 'c':

        /*
         * If this is a CopyDone message, exit COPY_OUT mode and let
         * caller read status with PQgetResult().  If we're in
         * COPY_BOTH mode, return to COPY_IN mode.
         */
        if (conn->asyncStatus == PGASYNC_COPY_BOTH)
          conn->asyncStatus = PGASYNC_COPY_IN;
        else
          conn->asyncStatus = PGASYNC_BUSY;
        return -1;
      default:      /* treat as end of copy */

        /*
         * Any other message terminates either COPY_IN or COPY_BOTH
         * mode.
         */
        conn->asyncStatus = PGASYNC_BUSY;
        return -1;
    }

    /* Drop the processed message and loop around for another */
    conn->inStart = conn->inCursor;
  }
}

/*
 * PQgetCopyData - read a row of data from the backend during COPY OUT
 * or COPY BOTH
 *
 * If successful, sets *buffer to point to a malloc'd row of data, and
 * returns row length (always > 0) as result.
 * Returns 0 if no row available yet (only possible if async is true),
 * -1 if end of copy (consult PQgetResult), or -2 if error (consult
 * PQerrorMessage).
 */
int
pqGetCopyData3(PGconn *conn, char **buffer, int async)
{
  int     msgLength;

  for (;;)
  {
    /*
     * Collect the next input message.  To make life simpler for async
     * callers, we keep returning 0 until the next message is fully
     * available, even if it is not Copy Data.
     */
    msgLength = getCopyDataMessage(conn);
    if (msgLength < 0)
      return msgLength; /* end-of-copy or error */
    if (msgLength == 0)
    {
      /* Don't block if async read requested */
      if (async)
        return 0;
      /* Need to load more data */
      if (pqWait(true, false, conn) ||
        pqReadData(conn) < 0)
        return -2;
      continue;
    }

    /*
     * Drop zero-length messages (shouldn't happen anyway).  Otherwise
     * pass the data back to the caller.
     */
    msgLength -= 4;
    if (msgLength > 0)
    {
      *buffer = (char *) malloc(msgLength + 1);
      if (*buffer == NULL)
      {
        printfPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("out of memory\n"));
        return -2;
      }
      memcpy(*buffer, &conn->inBuffer[conn->inCursor], msgLength);
      (*buffer)[msgLength] = '\0';  /* Add terminating null */

      /* Mark message consumed */
      conn->inStart = conn->inCursor + msgLength;

      return msgLength;
    }

    /* Empty, so drop it and loop around for another */
    conn->inStart = conn->inCursor;
  }
}

/*
 * PQgetline - gets a newline-terminated string from the backend.
 *
 * See fe-exec.c for documentation.
 */
int
pqGetline3(PGconn *conn, char *s, int maxlen)
{
  int     status;

  if (conn->sock == PGINVALID_SOCKET ||
    (conn->asyncStatus != PGASYNC_COPY_OUT &&
     conn->asyncStatus != PGASYNC_COPY_BOTH) ||
    conn->copy_is_binary)
  {
    printfPQExpBuffer(&conn->errorMessage,
              libpq_gettext("PQgetline: not doing text COPY OUT\n"));
    *s = '\0';
    return EOF;
  }

  while ((status = PQgetlineAsync(conn, s, maxlen - 1)) == 0)
  {
    /* need to load more data */
    if (pqWait(true, false, conn) ||
      pqReadData(conn) < 0)
    {
      *s = '\0';
      return EOF;
    }
  }

  if (status < 0)
  {
    /* End of copy detected; gin up old-style terminator */
    strcpy(s, "\\.");
    return 0;
  }

  /* Add null terminator, and strip trailing \n if present */
  if (s[status - 1] == '\n')
  {
    s[status - 1] = '\0';
    return 0;
  }
  else
  {
    s[status] = '\0';
    return 1;
  }
}

/*
 * PQgetlineAsync - gets a COPY data row without blocking.
 *
 * See fe-exec.c for documentation.
 */
int
pqGetlineAsync3(PGconn *conn, char *buffer, int bufsize)
{
  int     msgLength;
  int     avail;

  if (conn->asyncStatus != PGASYNC_COPY_OUT
    && conn->asyncStatus != PGASYNC_COPY_BOTH)
    return -1;       /* we are not doing a copy... */

  /*
   * Recognize the next input message.  To make life simpler for async
   * callers, we keep returning 0 until the next message is fully available
   * even if it is not Copy Data.  This should keep PQendcopy from blocking.
   * (Note: unlike pqGetCopyData3, we do not change asyncStatus here.)
   */
  msgLength = getCopyDataMessage(conn);
  if (msgLength < 0)
    return -1;       /* end-of-copy or error */
  if (msgLength == 0)
    return 0;       /* no data yet */

  /*
   * Move data from libpq's buffer to the caller's.  In the case where a
   * prior call found the caller's buffer too small, we use
   * conn->copy_already_done to remember how much of the row was already
   * returned to the caller.
   */
  conn->inCursor += conn->copy_already_done;
  avail = msgLength - 4 - conn->copy_already_done;
  if (avail <= bufsize)
  {
    /* Able to consume the whole message */
    memcpy(buffer, &conn->inBuffer[conn->inCursor], avail);
    /* Mark message consumed */
    conn->inStart = conn->inCursor + avail;
    /* Reset state for next time */
    conn->copy_already_done = 0;
    return avail;
  }
  else
  {
    /* We must return a partial message */
    memcpy(buffer, &conn->inBuffer[conn->inCursor], bufsize);
    /* The message is NOT consumed from libpq's buffer */
    conn->copy_already_done += bufsize;
    return bufsize;
  }
}

/*
 * PQendcopy
 *
 * See fe-exec.c for documentation.
 */
int
pqEndcopy3(PGconn *conn)
{
  PGresult   *result;

  if (conn->asyncStatus != PGASYNC_COPY_IN &&
    conn->asyncStatus != PGASYNC_COPY_OUT &&
    conn->asyncStatus != PGASYNC_COPY_BOTH)
  {
    printfPQExpBuffer(&conn->errorMessage,
              libpq_gettext("no COPY in progress\n"));
    return 1;
  }

  /* Send the CopyDone message if needed */
  if (conn->asyncStatus == PGASYNC_COPY_IN ||
    conn->asyncStatus == PGASYNC_COPY_BOTH)
  {
    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;
    }
  }

  /*
   * make sure no data is waiting to be sent, abort if we are non-blocking
   * and the flush fails
   */
  if (pqFlush(conn) && pqIsnonblocking(conn))
    return 1;

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

  /*
   * Non blocking connections may have to abort at this point.  If everyone
   * played the game there should be no problem, but in error scenarios the
   * expected messages may not have arrived yet.  (We are assuming that the
   * backend's packetizing will ensure that CommandComplete arrives along
   * with the CopyDone; are there corner cases where that doesn't happen?)
   */
  if (pqIsnonblocking(conn) && PQisBusy(conn))
    return 1;

  /* Wait for the completion response */
  result = PQgetResult(conn);

  /* Expecting a successful result */
  if (result && result->resultStatus == PGRES_COMMAND_OK)
  {
    PQclear(result);
    return 0;
  }

  /*
   * Trouble. For backwards-compatibility reasons, we issue the error
   * message as if it were a notice (would be nice to get rid of this
   * silliness, but too many apps probably don't handle errors from
   * PQendcopy reasonably).  Note that the app can still obtain the error
   * status from the PGconn object.
   */
  if (conn->errorMessage.len > 0)
  {
    /* We have to strip the trailing newline ... pain in neck... */
    char    svLast = conn->errorMessage.data[conn->errorMessage.len - 1];

    if (svLast == '\n')
      conn->errorMessage.data[conn->errorMessage.len - 1] = '\0';
    pqInternalNotice(&conn->noticeHooks, "%s", conn->errorMessage.data);
    conn->errorMessage.data[conn->errorMessage.len - 1] = svLast;
  }

  PQclear(result);

  return 1;
}


/*
 * PQfn - Send a function call to the POSTGRES backend.
 *
 * See fe-exec.c for documentation.
 */
PGresult *
pqFunctionCall3(PGconn *conn, Oid fnid,
        int *result_buf, int *actual_result_len,
        int result_is_int,
        const PQArgBlock *args, int nargs)
{
  bool    needInput = false;
  ExecStatusType status = PGRES_FATAL_ERROR;
  char    id;
  int     msgLength;
  int     avail;
  int     i;

  /* PQfn already validated connection state */

  if (pqPutMsgStart('F', false, conn) < 0 || /* function call msg */
    pqPutInt(fnid, 4, conn) < 0 || /* function id */
    pqPutInt(1, 2, conn) < 0 || /* # of format codes */
    pqPutInt(1, 2, conn) < 0 || /* format code: BINARY */
    pqPutInt(nargs, 2, conn) < 0) /* # of args */
  {
    pqHandleSendFailure(conn);
    return NULL;
  }

  for (i = 0; i < nargs; ++i)
  {             /* len.int4 + contents     */
    if (pqPutInt(args[i].len, 4, conn))
    {
      pqHandleSendFailure(conn);
      return NULL;
    }
    if (args[i].len == -1)
      continue;     /* it's NULL */

    if (args[i].isint)
    {
      if (pqPutInt(args[i].u.integer, args[i].len, conn))
      {
        pqHandleSendFailure(conn);
        return NULL;
      }
    }
    else
    {
      if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
      {
        pqHandleSendFailure(conn);
        return NULL;
      }
    }
  }

  if (pqPutInt(1, 2, conn) < 0) /* result format code: BINARY */
  {
    pqHandleSendFailure(conn);
    return NULL;
  }

  if (pqPutMsgEnd(conn) < 0 ||
    pqFlush(conn))
  {
    pqHandleSendFailure(conn);
    return NULL;
  }

  for (;;)
  {
    if (needInput)
    {
      /* Wait for some data to arrive (or for the channel to close) */
      if (pqWait(true, false, conn) ||
        pqReadData(conn) < 0)
        break;
    }

    /*
     * Scan the message. If we run out of data, loop around to try again.
     */
    needInput = true;

    conn->inCursor = conn->inStart;
    if (pqGetc(&id, conn))
      continue;
    if (pqGetInt(&msgLength, 4, conn))
      continue;

    /*
     * Try to validate message type/length here.  A length less than 4 is
     * definitely broken.  Large lengths should only be believed for a few
     * message types.
     */
    if (msgLength < 4)
    {
      handleSyncLoss(conn, id, msgLength);
      break;
    }
    if (msgLength > 30000 && !VALID_LONG_MESSAGE_TYPE(id))
    {
      handleSyncLoss(conn, id, msgLength);
      break;
    }

    /*
     * Can't process if message body isn't all here yet.
     */
    msgLength -= 4;
    avail = conn->inEnd - conn->inCursor;
    if (avail < msgLength)
    {
      /*
       * Before looping, enlarge the input buffer if needed to hold the
       * whole message.  See notes in parseInput.
       */
      if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
                   conn))
      {
        /*
         * XXX add some better recovery code... plan is to skip over
         * the message using its length, then report an error. For the
         * moment, just treat this like loss of sync (which indeed it
         * might be!)
         */
        handleSyncLoss(conn, id, msgLength);
        break;
      }
      continue;
    }

    /*
     * We should see V or E response to the command, but might get N
     * and/or A notices first. We also need to swallow the final Z before
     * returning.
     */
    switch (id)
    {
      case 'V':     /* function result */
        if (pqGetInt(actual_result_len, 4, conn))
          continue;
        if (*actual_result_len != -1)
        {
          if (result_is_int)
          {
            if (pqGetInt(result_buf, *actual_result_len, conn))
              continue;
          }
          else
          {
            if (pqGetnchar((char *) result_buf,
                     *actual_result_len,
                     conn))
              continue;
          }
        }
        /* correctly finished function result message */
        status = PGRES_COMMAND_OK;
        break;
      case 'E':     /* error return */
        if (pqGetErrorNotice3(conn, true))
          continue;
        status = PGRES_FATAL_ERROR;
        break;
      case 'A':     /* notify message */
        /* handle notify and go back to processing return values */
        if (getNotify(conn))
          continue;
        break;
      case 'N':     /* notice */
        /* handle notice and go back to processing return values */
        if (pqGetErrorNotice3(conn, false))
          continue;
        break;
      case 'Z':     /* backend is ready for new query */
        if (getReadyForQuery(conn))
          continue;
        /* consume the message and exit */
        conn->inStart += 5 + msgLength;
        /* if we saved a result object (probably an error), use it */
        if (conn->result)
          return pqPrepareAsyncResult(conn);
        return PQmakeEmptyPGresult(conn, status);
      case 'S':     /* parameter status */
        if (getParameterStatus(conn))
          continue;
        break;
      default:
        /* The backend violates the protocol. */
        printfPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("protocol error: id=0x%x\n"),
                  id);
        pqSaveErrorResult(conn);
        /* trust the specified message length as what to skip */
        conn->inStart += 5 + msgLength;
        return pqPrepareAsyncResult(conn);
    }
    /* Completed this message, keep going */
    /* trust the specified message length as what to skip */
    conn->inStart += 5 + msgLength;
    needInput = false;
  }

  /*
   * We fall out of the loop only upon failing to read data.
   * conn->errorMessage has been set by pqWait or pqReadData. We want to
   * append it to any already-received error message.
   */
  pqSaveErrorResult(conn);
  return pqPrepareAsyncResult(conn);
}


/*
 * Construct startup packet
 *
 * Returns a malloc'd packet buffer, or NULL if out of memory
 */
char *
pqBuildStartupPacket3(PGconn *conn, int *packetlen,
            const PQEnvironmentOption *options)
{
  char     *startpacket;

  *packetlen = build_startup_packet(conn, NULL, options);
  startpacket = (char *) malloc(*packetlen);
  if (!startpacket)
    return NULL;
  *packetlen = build_startup_packet(conn, startpacket, options);
  return startpacket;
}

/*
 * Build a startup packet given a filled-in PGconn structure.
 *
 * We need to figure out how much space is needed, then fill it in.
 * To avoid duplicate logic, this routine is called twice: the first time
 * (with packet == NULL) just counts the space needed, the second time
 * (with packet == allocated space) fills it in.  Return value is the number
 * of bytes used.
 */
static int
build_startup_packet(const PGconn *conn, char *packet,
           const PQEnvironmentOption *options)
{
  int     packet_len = 0;
  const PQEnvironmentOption *next_eo;
  const char *val;

  /* Protocol version comes first. */
  if (packet)
  {
    ProtocolVersion pv = pg_hton32(conn->pversion);

    memcpy(packet + packet_len, &pv, sizeof(ProtocolVersion));
  }
  packet_len += sizeof(ProtocolVersion);

  /* Add user name, database name, options */

#define ADD_STARTUP_OPTION(optname, optval) \
  do { \
    if (packet) \
      strcpy(packet + packet_len, optname); \
    packet_len += strlen(optname) + 1; \
    if (packet) \
      strcpy(packet + packet_len, optval); \
    packet_len += strlen(optval) + 1; \
  } while(0)

  if (conn->pguser && conn->pguser[0])
    ADD_STARTUP_OPTION("user", conn->pguser);
  if (conn->dbName && conn->dbName[0])
    ADD_STARTUP_OPTION("database", conn->dbName);
  if (conn->replication && conn->replication[0]0)
    ADD_STARTUP_OPTION("replication", conn->replication);
  if (conn->pgoptions && conn->pgoptions[0])
    ADD_STARTUP_OPTION("options", conn->pgoptions);
  if (conn->send_appname)
  {
    /* Use appname if present, otherwise use fallback */
    val = conn->appname ? conn->appname230 : conn->fbappname5.36k;
    if (val && val[0]296)
      ADD_STARTUP_OPTION("application_name", val);
  }

  if (conn->client_encoding_initial && conn->client_encoding_initial[0]30)
    ADD_STARTUP_OPTION("client_encoding", conn->client_encoding_initial);

  /* Add any environment-driven GUC settings needed */
  for (next_eo = options; next_eo->envName; next_eo++16.7k)
  {
    if ((val = getenv(next_eo->envName)) != NULL)
    {
      if (pg_strcasecmp(val, "default") != 0)
        ADD_STARTUP_OPTION(next_eo->pgName, val);
    }
  }

  /* Add trailing terminator */
  if (packet)
    packet[packet_len] = '\0';
  packet_len++;

  return packet_len;
}

YugabyteDB (2.13.1.0-b60, 21121d69985fbf76aa6958d8f04a9bfa936293b5)

Coverage Report

Created: 2022-03-22 16:43