t_rcvudata.3 (2010 09)

t
t_rcvudata(3) t_rcvudata(3)
NAME
t_rcvudata() - receive a data unit from remote transport provider user
SYNOPSIS
#include <xti.h> /* for X/OPEN Transport Interface - XTI */
/* or */
#include <tiuser.h> /* for Transport Layer Interface - TLI */
int t_rcvudata (fd, unitdata, flags);
inf fd;
struct t_unitdata *unitdata;
int *flags;
DESCRIPTION
The t_rcvudata() function is used in connectionless-mode to receive a data unit from a remote tran-
sport provider user. The argument fd identifies the local transport endpoint through which data will be
received. unitdata holds information associated with the received data unit. flags is set on return to indi-
cate that the complete data unit was not received. The argument unitdata points to a
t_unitdata
structure containing the following members:
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
The type netbuf structure is defined in the <xti.h> or <tiuser.h> header file. This structure,
which is used to define buffer parameters, has the following members:
unsigned int maxlen maximum byte length of the data buffer
unsigned int len actual byte length of data written to buffer
char *buf points to buffer location
The maxlen field of addr , opt and udata must be set before calling 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() executes in the synchronous operating mode. The t_rcvudata() function
waits for data to arrive at the transport endpoint specified by fd before returning control to the transport
user who called this function. However, when the transport endpoint, specified by the fd parameter, has
the
O_NONBLOCK option set by t_open() or fcntl() function, the t_rcvudata() function executes
in asynchronous mode. In asynchronous mode, when a data unit is unavailable, control is immediately
returned to the caller.
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 called to retrieve the rest of the data unit. Subsequent calls to t_rcvudata() will return
zero for the length of the address and options until the full data unit has been received.
Valid States
T_IDLE
Fork Safety
t_rcvudata is not fork-safe.
RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a value of 1 is returned and
t_errno
is set to indicate the error.
ERRORS
On failure,
t_errno is set to one of the following:
[TBADF] The specified file descriptor does not refer to a transport endpoint.
[TNODATA]
O_NONBLOCK was set, but no data units are currently available from the transport
provider.
HP-UX 11i Version 3: September 2010 1 Hewlett-Packard Company 1

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