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t_sndudata - Sends a data unit


XTI Library (libxti.a)


#include <xti.h> int t_sndudata( int fd, struct t_unitdata *unitdata) ;


Interfaces documented on this reference page conform to industry standards as follows: t_sndudata: XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags.


The following table summarizes the relevance of input and output parameters before and after t_sndudata() is called: Parameters Before Call After Call _________________________________________________ fd y n unitdata->addr.maxlen n n unitdata->addr.len y n unitdata->addr.buf y(y) n unitdata->opt.maxlen n n unitdata->opt.len y n unitdata->opt.buf o(o) n unitdata->udata.maxlen n n unitdata->udata.len y n unitdata->udata.buf y(y) n Notes to Table: y This is a meaningful parameter. (y) The content of the object pointed to by y is meaningful. o This is a meaningful but optional parameter. (o) The content of the object pointed to by o is meaningful. n This is not a meaningful parameter. fd Specifies a file descriptor returned by the t_open() function that identifies the transport endpoint through which data is sent. unitdata Points to a type t_unitdata structure used to specify a data unit being sent through the transport endpoint specified by the fd parameter. The t_unitdata structure has the following members: struct netbuf addr References a buffer for protocol address information of the remote transport user. The type netbuf structure referenced by this member is defined in the xti.h include file and has the following members: unsigned int maxlen Specifies a maximum byte length of the data buffer. unsigned int len Specifies the actual byte length of the data written to the buffer. char *buf Points to the buffer location. struct netbuf opt Identifies options that the user wants associated with this request. The user may choose not to specify what protocol options are associated with the transfer by setting the len field of opt to zero. In this case, the provider may use default options. struct netbuf udata Specifies the user data unit that is being sent to the remote transport user. The unitdata->addr.maxlen, unitdata->opt.maxlen, and unitdata->udata.maxlen parameters are not meaningful with the t_sndudata() function. If the udata.len parameter is specified as 0 (zero), and the underlying transport service does not support the sending of 0 (zero) octets, t_errno is set to [TBADDATA] and -1 is returned. If the amount of data specified in udata exceeds the TSDU size as returned in the tsdu field of the info argument of t_open() or t_getinfo(), a [TBADDATA] error is generated. If t_sndudata() is called before the destination user has activated its transport endpoint, the data unit may be discarded. (See t_bind().)


The t_sndudata() function can be called only in the T_IDLE transport provider state.


The t_sndudata() function is an XTI connectionless service function that is used to send a data unit to a remote transport user. By default, t_sndudata() executes in the synchronous operating mode. The t_sndudata() function waits for the transport provider to accept the data before returning control to the calling transport user. When the transport endpoint specified by the fd parameter has been previously opened with the O_NONBLOCK flag set in the t_open() or fcntl() functions, the t_sndudata() function executes in asynchronous mode. In asynchronous mode, when a data unit is not accepted control is immediately returned to the caller. The t_look() function or the EM interface can be used to determine when flow control restrictions have been lifted.


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


If the t_sndudata() function fails, t_errno may be set to one of the following values: [TBADDATA] Illegal amount of data. Zero octets is not supported. [TBADF] File descriptor fd is not a valid transport endpoint. [TFLOW] Asynchronous mode is indicated because O_NONBLOCK was set, but the transport provider cannot accept the data because of flow-control restrictions. [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 t_sndudata() function was issued in the wrong sequence on the transport endpoint referenced by the fd parameter. [TSYSERR] A system error occurred during execution of this function. A protocol error may not cause the t_sndudata() function to fail until a subsequent call is made to access the transport endpoint specified by the fd parameter. [TBADADDR] The specified protocol address was in an incorrect format or contained illegal information. [TBADOPT] The specified options were in an incorrect format or contained illegal information. [TPROTO] This error indicates that a communication problem has been detected between XTI and the transport provider for which there is no other suitable XTI(t_errno).


Functions: fcntl(2), t_alloc(3), t_open(3), t_rcvuderr(3), t_rcvudata(3)