t_alloc(3N)           (Networking Support Utilities)            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 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(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.




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   t_alloc(3N)           (Networking Support Utilities)            t_alloc(3N)


         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(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: Networking Interfaces.

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















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