t_alloc(3N)             NETWORK FUNCTIONS             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



            Last change: Networking Support Utilities           1

t_alloc(3N)             NETWORK FUNCTIONS             t_alloc(3N)



               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 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).
     UNIX System V Network Programmer's Guide.

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

















            Last change: Networking Support Utilities           2