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Technical Reference: Base Operating System and Extensions , Volume 2

t_rcvreldata Subroutine


Receive an orderly release indication or confirmation containing user data.



#include <xti.h>
int t_rcvreldata(
    int fd,
    struct t_discon *discon)


This function is used to receive an orderly release indication for the incoming direction of data transfer and to retrieve any user data sent with the release. The argument fd identifies the local transport endpoint where the connection exists, and discon points to a t_discon structure containing the following members:

struct netbuf udata;
int reason;
int sequence;

After receipt of this indication, the user may not attempt to receive more data via t_rcv or t_rcvv (t_rcvv Subroutine). Such an attempt will fail with t_error set to [TOUTSTATE]. However, the user may continue to send data over the connection if t_sndrel or t_sndreldata (t_sndreldata Subroutine) has not been called by the user.

The field reason specifies the reason for the disconnection through a protocol-dependent reason code, and udata identifies any user data that was sent with the disconnection; the field sequence is not used.

If a user does not care if there is incoming data and does not need to know the value of reason, discon may be a null pointer, and any user data associated with the disconnection will be discarded.

If discon->udata.maxlen is greater than zero and less than the length of the value, t_rcvreldata fails with t_errno set to [TBUFOVFLW].

This function is an optional service of the transport provider, only supported by providers of service type T_COTS_ORD. The flag T_ORDRELDATA in the info->flag field returned by t_open or t_getinfo indicates that the provider supports orderly release user data; when the flag is not set, this function behaves as t_rcvrel and no user data is returned.

This function may not be available on all systems.

Parameters Before call After call
fd x /
discon-> udata.maxlen x
discon-> udata.len /
discon-> udata.buf ?
discon-> reason /
discon-> sequence /

Valid States


Return Values

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and t_errno is set to indicate an error.

Error Codes

On failure, the t_errno subroutine is set to one of the following:

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

The number of bytes allocated for incoming data (maxlen) is greater than 0 but not sufficient to store the data, and the disconnection information to be returned in discon will be discarded. The provider state, as seen by the user, will be changed as if the data was successfully retrieved.

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

No orderly release indication currently exists on the specified transport endpoint.

Orderly release is not supported by the underlying transport provider.

The communications endpoint referenced by fd is not in one of the states in which a call to this function is valid.

This error indicates that a communication problem has been detected between XTI and the transport provider for which there is no other suitable XTI error (t_errno).

A system error has occurred during execution of this function.

Related Information

The t_getinfo, t_open, t_sndreldata (t_sndreldata Subroutine), t_rcvrel, t_sndrel subroutines.

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