Networking Services Library Functions t_rcv(3NSL)
NAME
t_rcv - receive data or expedited data sent over a connec-
tionSYNOPSIS
#include
int t_rcv(int fd, void *buf, unsigned int nbytes, int *flags);
DESCRIPTION
This function is part of the XTI interfaces which evolved from the TLI interfaces. XTI represents the future evolution of these interfaces. However, TLI interfaces are supported for compatibility. When using a TLI function that has the same name as an XTI function, the tiuser.h header file must be used. Refer to the TLI COMPATIBILITY section for a description of differences between the two interfaces. This function receives either normal or expedited data. The argument 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. The argument flags may be set on returnfrom 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. How-
ever, if O_NONBLOCK is set by means of t_open(3NSL) or
fcntl(2), 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 dataunit (ETSDU) must be received in multiple t_rcv() calls. In
the asynchronous mode, or under unusual conditions (forexample, the arrival of a signal or T_EXDATA event), the
T_MORE flag may be set on return from the t_rcv() call even
when the number of bytes received is less than the size ofthe receive buffer specified. Each t_rcv() with the T_MORE
flag set indicates that another t_rcv() must follow to get
more data for the current TSDU. The end of the TSDU is iden-
tified by the return of a t_rcv() call with the T_MORE flag
not set. If the transport provider does not support the con-
cept of a TSDU as indicated in the info argument on returnfrom t_open(3NSL) or t_getinfo(3NSL), the T_MORE flag is
not meaningful and should be ignored. If nbytes is greaterSunOS 5.11 Last change: 24 Aug 2007 1
Networking Services Library Functions t_rcv(3NSL)
than zero on the call to t_rcv(), t_rcv() will return 0
only if the end of a TSDU is being returned to the user.On return, the data is expedited if T_EXPEDITED is set in
flags. If T_MORE is also set, it indicates that the number
of expedited bytes exceeded nbytes, a signal has interrupted the call, or that an entire ETSDU was not available (only for transport protocols that support fragmentation ofETSDUs). The rest of the ETSDU will be returned by subse-
quent calls to t_rcv() which will return with T_EXPEDITED
set in flags. The end of the ETSDU is identified by thereturn of a t_rcv() call with T_EXPEDITED set and T_MORE
cleared. If the entire ETSDU is not available it is possi-
ble for normal data fragments to be returned between the initial and final fragments of an ETSDU.If a signal arrives, t_rcv() returns, giving the user any
data currently available. If no data is available, t_rcv()
returns -1, sets t_errno to TSYSERR and errno to EINTR.
If some data is available, t_rcv() returns the number of
bytes received and T_MORE is set in flags.
In synchronous mode, the only way for the user to be noti-
fied of the arrival of normal or expedited data is to issuethis function or check for the T_DATA or T_EXDATA events
using the t_look(3NSL) function. Additionally, the process
can arrange to be notified by means of the EM interface.RETURN VALUES
On successful completion, t_rcv() returns the number of
bytes received. Otherwise, it returns -1 on failure and
t_errno is set to indicate the error.
VALID STATEST_DATAXFER, T_OUTREL.
ERRORS
On failure, t_errno is set to one of the following:
TBADF The specified file descriptor does not refer to a transport endpoint. TLOOK An asynchronous event has occurred on this transport endpoint and requires immediate attention.SunOS 5.11 Last change: 24 Aug 2007 2
Networking Services Library Functions t_rcv(3NSL)
TNODATA O_NONBLOCK was set, but no data is currently
available from the transport provider.TNOTSUPPORT This function is not supported by the under-
lying transport provider. TOUTSTATE The communications endpoint referenced by fd is not in one of the states in which a call to this function is valid. TPROTO This error indicates that a communication problem has been detected between XTI and the transport provider for which there is noother suitable XTI error (t_errno).
TSYSERR A system error has occurred during execution of this function. TLI COMPATIBILITY The XTI and TLI interface definitions have common names butuse different header files. This, and other semantic differ-
ences between the two interfaces are described in the sub-
sections below. Interface HeaderThe XTI interfaces use the header file, xti.h. TLI inter-
faces should not use this header. They should use the header:#include
Error Description ValuesThe t_errno value that can be set by the XTI interface and
cannot be set by the TLI interface is: TPROTOATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:SunOS 5.11 Last change: 24 Aug 2007 3
Networking Services Library Functions t_rcv(3NSL)
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
fcntl(2), t_getinfo(3NSL), t_look(3NSL), t_open(3NSL),
t_snd(3NSL), attributes(5), standards(5)
SunOS 5.11 Last change: 24 Aug 2007 4