T_ALLOC(3N)          INTERACTIVE UNIX System          T_ALLOC(3N)



          NAME
               t_alloc - allocate a library structure

          SYNOPSIS
               #include <tiuser.h>

               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 refer-
               enced 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(3).  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.


          Rev. Networking Support Utilities                          Page 1

          T_ALLOC(3N)          INTERACTIVE UNIX System          T_ALLOC(3N)



               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 ini-
               tialize the buf pointer and maxlen [see netbuf in intro(3)
               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.

               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.

          SEE ALSO
               intro(3), t_free(3N), t_getinfo(3N), t_open(3N).
               Programmer's Guide.

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


















          Rev. Networking Support Utilities                          Page 2