T_RCV(3N)                  DG/UX 4.30                   T_RCV(3N)



     NAME
          t_rcv - receive data or expedited data sent over a
          connection

     SYNOPSIS
          int t_rcv(fd, buf, nbytes, flags)
          int fd;
          char *buf;
          unsigned nbytes;
          int *flags;

     DESCRIPTION
          This function receives either normal or expedited data.  Fd
          identifies the local transport endpoint through which data
          will arrive, buf points to a receive buffer where user data
          will be placed, and nbytes specifies the size of the receive
          buffer.  Flags may be set on return from t_rcv and specifies
          optional flags as described below.

          By default, t_rcv operates in synchronous mode and will wait
          for data to arrive if none is currently available.  However,
          if O_NDELAY is set (via t_open or fcntl), t_rcv will execute
          in asynchronous mode and will fail if no data is available.
          (See TNODATA below.)

          On return from the call, if T_MORE is set in flags this
          indicates that there is more data and the current transport
          service data unit (TSDU) or expedited transport service data
          unit (ETSDU) must be received in multiple t_rcv calls.  Each
          t_rcv with the T_MORE flag set indicates that another t_rcv
          must follow immediately to get more data for the current
          TSDU.  The end of the TSDU is identified by the return of a
          t_rcv call with the T_MORE flag not set.  If the transport
          provider does not support the concept of a TSDU as indicated
          in the info argument on return from t_open or t_getinfo, the
          T_MORE flag is not meaningful and should be ignored.

          On return, the data returned is expedited data if
          T_EXPEDITED is set in flags.  If the number of bytes of
          expedited data exceeds nbytes, t_rcv will set T_EXPEDITED
          and T_MORE on return from the initial call.  Subsequent
          calls to retrieve the remaining ETSDU will not have
          T_EXPEDITED set on return.  The end of the ETSDU is
          identified by the return of a t_rcv call with the T_MORE
          flag not set.

          If expedited data arrives after part of a TSDU has been
          retrieved, receipt of the remainder of the TSDU will be
          suspended until the ETSDU has been processed.  Only after
          the full ETSDU has been retrieved (T_MORE not set) will the
          remainder of the TSDU be available to the user.




     Licensed material--property of copyright holder(s)         Page 1

     T_RCV(3N)                  DG/UX 4.30                   T_RCV(3N)



          On failure, t_errno may be set to one of the following:

          [TBADF]            The specified file descriptor does not
                             refer to a transport endpoint.

          [TNODATA]          O_NDELAY was set, but no data is
                             currently available from the transport
                             provider.

          [TLOOK]            An asynchronous event has occurred on
                             this transport endpoint and requires
                             immediate attention.

          [TNOTSUPPORT]      This function is not supported by the
                             underlying transport provider.

          [TSYSERR]          A system error has occurred during
                             execution of this function.

     SEE ALSO
          t_open(3N), t_snd(3N).

     DIAGNOSTICS
          On successful completion, t_rcv returns the number of bytes
          received, and it returns -1 on failure and t_errno is set to
          indicate the error.





























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