NAME

t_rcvudata − receive a data unit

SYNOPSIS

#include <tiuser.h>

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

DESCRIPTION

This function is used in connectionless mode to receive a data unit from another transport user.  fd 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 netbuf addr;
struct netbuf opt;
struct netbuf udata;

The maxlen [see netbuf in intro(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 (via t_open or fcntl), 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. 

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

[TBUFOVFLW] The number of bytes allocated for the incoming protocol address or options is 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. 

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

[TOUTSTATE The function was issued in the wrong sequence. 

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

SEE ALSO

intro(3N), t_rcvuderr(3N), t_sndudata(3N).  CX/UX Networking Reference Manual

DIAGNOSTICS

t_rcvudata returns 0 on successful completion and −1 on failure and t_errno is set to indicate the error. 

CX/UX Networking