t_alloc(3N)							   t_alloc(3N)

NAME    [Toc]    [Back]

     t_alloc - allocate	a library structure

SYNOPSIS    [Toc]    [Back]

     #ifdef _XOPEN_SOURCE
     #include <xti.h>
     #else
     #include <tiuser.h>
     #endif

     char *t_alloc(fd, struct_type, fields)
     int fd;
     int struct_type;
     int fields;

DESCRIPTION    [Toc]    [Back]

     The t_alloc function dynamically allocates	memory for the various
     transport function	argument structures as specified below.	 This function
     will allocate memory for the specified structure, and will	also allocate
     memory for	buffers	referenced by the structure.

     The structure to allocate is specified by struct_type, and	can be one of
     the following:

     T_BIND	      struct t_bind

     T_CALL	      struct t_call

     T_OPTMGMT	      struct t_optmgmt

     T_DIS	      struct t_discon

     T_UNITDATA	      struct t_unitdata

     T_UDERROR	      struct t_uderr

     T_INFO	      struct t_info

     where each	of these structures may	subsequently be	used as	an argument to
     one or more transport functions.

     Each of the above structures, except T_INFO, contains at least one	field
     of	type struct netbuf.  netbuf is described in intro(3N).	For each field
     of	this type, the user may	specify	that the buffer	for that field should
     be	allocated as well.  The	fields argument	specifies this option, where
     the argument is the bitwise-OR of any of the following:

     T_ADDR    The addr	field of the t_bind, t_call, t_unitdata, or t_uderr
	       structures.






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t_alloc(3N)							   t_alloc(3N)



     T_OPT     The opt field of	the t_optmgmt, t_call, t_unitdata, or t_uderr
	       structures.

     T_UDATA   The udata field of the t_call, t_discon,	or t_unitdata
	       structures.

     T_ALL     All relevant fields of the given	structure.

     For each field specified in fields, t_alloc will allocate memory for the
     buffer associated with the	field, and initialize the buf pointer and
     maxlen [see netbuf	in intro(3N) for description of	buf and	maxlen]	field
     accordingly.  The length of the buffer allocated will be based on the
     same size information that	is returned to the user	on t_open and
     t_getinfo.	 Thus, fd must refer to	the transport endpoint through which
     the newly allocated structure will	be passed, so that the appropriate
     size information can be accessed.	If the size value associated with any
     specified field is	-1 or -2 (see t_open or	t_getinfo), t_alloc will be
     unable to determine the size of the buffer	to allocate and	will fail,
     setting t_errno to	TSYSERR	and errno to EINVAL.  For any field not
     specified in fields, buf will be set to NULL and maxlen will be set to
     zero.

     Use of t_alloc to allocate	structures will	help ensure the	compatibility
     of	user programs with future releases of the transport interface.

     This function resides within both the X/Open compliant libxnet and	the
     SVR4 compliant libnsl Network Services libraries.	Network	Services
     applications which	require	X/Open compliance must link-load with -lxnet.
     Network Services applications which require SVR4 compliance must linkload
 with -lnsl.

     On	failure, t_errno may be	set to one of the following:

     TBADF	    The	specified file descriptor does not refer to a
		    transport endpoint.

     TSYSERR	    A system error has occurred	during execution of this
		    function.

     TNOSTRUCTYPE   Unsupported	struct_type requested.	This can include a
		    request for	a structure type which is inconsistent with
		    the	transport provider type	specified, that	is,
		    connection-oriented	or connectionless.

SEE ALSO    [Toc]    [Back]

     intro(3N),	t_free(3N), t_getinfo(3N), t_open(3N)

DIAGNOSTICS    [Toc]    [Back]

     On	successful completion, t_alloc returns a pointer to the	newly
     allocated structure.  On failure, NULL is returned.


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