NAME

t_rcvudata − receive a data unit

SYNOPSIS

cc [ flag ... ] file ... −lnsl [ library ... ]

#include <tiuser.h>

int t_rcvudata(int fildes, struct t_unitdata ∗unitdata, int ∗flags);

MT-LEVEL

MT-Safe

DESCRIPTION

This function is used in connectionless mode to receive a data unit from another transport user.  fildes identifies the local transport endpoint through which data will be received, unitdata holds information associated with the received data unit, and flags is set on return to indicate that the complete data unit was not received.  unitdata points to a t_unitdata structure containing the following members:

struct netbufaddr;
struct netbufopt;
struct netbufudata;

The maxlen (see netbuf in t_connect(3N)) field of addr, opt, and udata must be set before issuing this function to indicate the maximum size of the buffer for each. 

On return from this call, addr specifies the protocol address of the sending user, opt identifies protocol-specific options that were associated with this data unit, and udata specifies the user data that was received. 

By default, t_rcvudata() operates in synchronous mode and will wait for a data unit to arrive if none is currently available.  However, if O_NDELAY or O_NONBLOCK is set (using t_open(3N) or fcntl(2)), t_rcvudata() will execute in asynchronous mode and will fail if no data units are available. 

If the buffer defined in the udata field of unitdata is not large enough to hold the current data unit, the buffer will be filled and T_MORE will be set in flags on return to indicate that another t_rcvudata() should be issued to retrieve the rest of the data unit.  Subsequent t_rcvudata() call(s) will return zero for the length of the address and options until the full data unit has been received. 

RETURN VALUES

t_rcvudata() returns 0 on successful completion.  On failure t_rcvudata() returns −1, t_errno is set to indicate the error, and possibly errno is set. 

ERRORS

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

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

TBUFOVFLW The number of bytes allocated for the incoming protocol address or options is greater than zero but not sufficient to store the information.  The unit data information to be returned in unitdata will be discarded. 

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

TNODATA O_NDELAY or O_NONBLOCK was set, but no data units are currently available from the transport provider. 

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

TSYSERR A system error has occurred during execution of this function, errno will be set to the specific error. 

SEE ALSO

fcntl(2), t_connect(3N), t_rcvuderr(3N), t_sndudata(3N)

Network Interfaces Programmer’s Guide

NOTES

This interface is safe in multithreaded applications. 

SunOS 5.4  —  Last change: 27 Jan 1994