NAME

t_alloc − allocate a library structure

SYNOPSIS

cc [ flag ... ] file ... −lnsl [ library ... ]

#include <tiuser.h>

char ∗t_alloc(int fildes, int struct_type, int fields);

MT-LEVEL

MT-Safe

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. 

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, fildes 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. 

RETURN VALUES

On successful completion, t_alloc() returns a pointer to the newly allocated structure.  On failure, NULL is returned, t_errno is set to indicate the error, and possibly errno is set. 

ERRORS

On failure, t_errno will 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, errno will be set to the specific error. 

SEE ALSO

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

SunOS 5.1 Network Interfaces Programmer’s Guide

NOTES

This interface is safe in multithreaded applications. 

SunOS 5.2  —  Last change: 22 Jan 1993