t_open(3xti)
Name
t_open − establish a transport endpoint
Syntax
#include <xti.h>
#include <fcntl.h>
int t_open(name, oflag, info)
char *name;
int oflag;
struct t_info *info;
Arguments
namePoints to a transport provider identifier.
oflagIdentifies any open flags as in open(). The oflag argument is constructed from O_RDWR optionally ORed with O_NONBLOCK. These flags are defined by the header file <fcntl.h>.
infoReturns various default characteristics of the underlying transport protocol by setting fields in the info structure. This argument points to a t_info() structure that contains the following members:
long addr/* max size of the transport protocol address */
long options/* max number of bytes of protocol specific options */
long tsdu/* max size of a transport service data unit (TSDU) */
long etsdu/* max size of expedited transport service data unit (ETSDU) */
long connect/* max amount of data allowed on connection establishment functions */
long discon/* max amount of data allowed on t_snddis() and t_rcvdis() functions */
long servtype/* service type supported by the transport provider */
The values of the fields have the following meanings:
addrA value greater than or equal to zero indicates the maximum size of a transport protocol address; a value of −1 specifies that there is no limit on the address size; and a value of −2 specifies that the transport provider does not provide user access to transport protocol addresses.
optionsA value greater than or equal to zero indicates the maximum number of bytes of protocol-specific options supported by the provider; a value of −1 specifies that there is no limit on the option size; and a value of −2 specifies that the transport provider does not support user−settable options.
tsduA value greater than zero specifies the maximum size of a transport service data unit (TSDU); a value of zero specifies that the transport provider does not support the concept of TSDU; although it does support the sending of a data stream with no logical boundaries preserved across a connection; a value of −1 specifies that there is no limit on the size of an ETSDU; and a value of −2 specifies that the transfer of normal data is not supported by the transport provider.
etsduA value greater than zero specifies the maximum size of an expedited transport service data unit (ETSDU); a value zero specifies that the transport provider does not support the concept of ETSDU, although it does support the sending of an expedited data stream with no logical boundaries preserved across a connection; a value of −1 specifies that there is no limit on the size of an ETSDU; and a value −2 specifies that the transfer of expedited data is not supported by the transport provider.
connectA value greater than or equal to zero specifies the maximum amount of data that may be associated with connection establishment functions; a value of −1 specifies that there is no limit on the amount of data sent during connection establishment; and a value of −2 specifies that the transport provider does not allow data to be sent with connection establishment functions.
disconA value greater than or equal to zero specifies the maximum amount of data that may be associated with the t_snddis() and t_rcvdis() functions; a value of −1 specifies that there is no limit on the amount of data sent with these abortive release functions; and a −2 specifies that the transport provider does not allow data to be sent with abortive release functions.
servtypeThis field specifies the service type supported by the transport provider, as described.
If a transport user is concerned with protocol independence, the sizes can be accessed to determine how large the buffers must be to hold each piece of information. Alternately, the t_alloc() function may be used to allocate these buffers. An error will result if a transport user exceeds the allowed data size on any function.
The servtype field of info specifies one of the following values on return.
T_COTSThe transport provider supports a connection-mode service but does not support the optional orderly release facility.
T_COTS_ORDThe transport provider supports a connection-mode service with the optional orderly release facility.
T_CLTSThe transport provider supports a connectionless-mode service. For this service type, t_open() returns −2 for etsdu, connect, and discon.
A single transport endpoint may support only one of the above services at one time. If info is set to NULL by the transport user, no protocol information is returned by t_open().
Description
The t_open() function must be called as the first step in the initialization of a transport endpoint. This function establishes a transport endpoint by supplying a transport provider identifier that indicates a particular transport provider, that is a transport protocol, and returns a file descriptor that identifies that endpoint.
The t_open() function returns a file descriptor that is used by all subsequent functions to identify that particular local transport endpoint.
| Parameters | Before Call | After Call |
| name | x | / |
| oflag | x | / |
| info->addr | / | x |
| info->options | / | x |
| info->tsdu | / | x |
| info->etsdu | / | x |
| info->connect | / | x |
| info->discon | / | x |
| info->servtype | / | x |
Return Values
Upon successful completion, t_open() returns a file descriptor. On failure, −1 is returned, and t_errno is set to indicate the error.
Diagnostics
On failure, t_errno is set to one of the following:
[TBADFLAG] An invalid flag is specified.
[TBADNAME] Invalid transport provider name.
[TSYSERR] A system error has occurred during execution of this function.