t_rcvudata(3N) t_rcvudata(3N)
NAME
trcvudata - receive a data unit
SYNOPSIS
#include <sys/tiuser.h>
int trcvudata(int fd, struct tunitdata *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 end-
point 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 tunitdata structure containing the following members:
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
The maxlen 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 asso-
ciated with this data unit, and udata specifies the user data that was
received.
By default, trcvudata operates in synchronous mode and will wait for
a data unit to arrive if none is currently available. However, if
ONDELAY or ONONBLOCK is set (via topen or fcntl), trcvudata will
execute in asynchronous mode and will fail if no data units are avail-
able.
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
TMORE will be set in flags on return to indicate that another
trcvudata should be issued to retrieve the rest of the data unit.
Subsequent trcvudata call(s) will return zero for the length of the
address and options until the full data unit has been received.
ERRORS
On failure, terrno may be set to one of the following:
TBADF The specified file descriptor does not refer to a
transport endpoint.
TNODATA ONDELAY or ONONBLOCK was set, but no data units are
currently available from the transport provider.
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t_rcvudata(3N) t_rcvudata(3N)
TBUFOVFLW The number of bytes allocated for the incoming proto-
col 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.
TSYSERR A system error has occurred during execution of this
function.
DIAGNOSTICS
trcvudata returns 0 on successful completion and -1 on failure and
terrno is set to indicate the error.
SEE ALSO
trcvuderr(3N), tsndudata(3N).
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