t_alloc - allocate a library structure

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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 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 t_connect.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 t_connect.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.3n and t_getinfo.3n 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, the underlying service provider can support a buffer of unlimited size. If this is the case, t_alloc() will allocate a buffer with the default size 1024 bytes. See the NOTES section for information regarding memory allocation for buffers other than 1024 bytes. If the size value is -2, t_alloc() will set the buffer pointer to NULL and the buffer maximum size to 0, and then will return success (see t_open.3n or t_getinfo.3n
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

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

NOTES

If the underlying service provider supports a buffer of unlimited size in the netbuf structure (see t_connect.3n t_alloc() will return a buffer of size 1024 bytes. If a larger size buffer is required, it will need to be allocated separately using a memory allocation routine such as malloc.3c The buf and maxlen fields of the netbuf data structure can then be updated with the address of the new buffer and the 1024 byte buffer originally allocated by t_alloc() can be freed using free.3c

This interface is safe in multithreaded applications.

Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).

Last modified 21/April/97