t_alloc(3N)

NAME
     t_alloc - allocate a library structure

SYNOPSIS
     #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
     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.

     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 link-
     load 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
     intro(3N), t_free(3N), t_getinfo(3N), t_open(3N)

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