(TLI/XTI)

t_alloc(NET)

t_alloc -- allocate a library structure

Syntax

TLI syntax

cc . . . -lnsl

#include <sys/tiuser.h>

char * t_alloc (fd, struct_type, fields)
int fd, struct_type, fields;

XTI syntax

cc . . . -lxti

#include <xti.h>

char *t_alloc (fd, struct_type, fields)
int fd, struct_type, fields;

Description

The t_alloc function dynamically allocates memory for the various transport function argument structures as specified below. This function allocates memory for the specified structure, and also allocates memory for buffers referenced by the structure.

The structure to allocate is specified by struct_type, and can be one of the following:

TLI struct_type XTI struct_type struct

T_BIND T_BIND_STR t_bind

T_CALL T_CALL_STR t_call

T_DIS T_DIS_STR t_discon

T_INFO T_INFO_STR t_info

T_OPTMGMT T_OPTMGMT_STR t_optmgmt

T_UDERROR T_UDERROR_STR t_uderr

T_UNITDATA T_UNITDATA_STR t_unitdata

Each of these structures may subsequently be used as an argument to one or more transport functions.

TLI struct_type	XTI struct_type	struct
T_BIND	T_BIND_STR	t_bind
T_CALL	T_CALL_STR	t_call
T_DIS	T_DIS_STR	t_discon
T_INFO	T_INFO_STR	t_info
T_OPTMGMT	T_OPTMGMT_STR	t_optmgmt
T_UDERROR	T_UDERROR_STR	t_uderr
T_UNITDATA	T_UNITDATA_STR	t_unitdata

Each of the previously listed structures, except T_INFO (TLI) or T_INFO_STR (XTI), contains at least one field of type struct netbuf. netbuf is described in netbuf(FP). 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_ALL: All relevant fields of the given structure.
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.

For each field specified in fields, t_alloc allocates memory for the buffer associated with the field, and initialize the buf pointer and maxlen (see netbuf in netbuf(FP) for a description of the buf and maxlen) fields accordingly. The length of the buffer allocated is 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 is 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 is unable to determine the size of the buffer to allocate and fails, setting t_errno to TSYSERR and errno to EINVAL. For any field not specified in fields, buf is set to NULL and maxlen is set to zero.

Use of t_alloc to allocate structures helps 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, it returns NULL.

Diagnostics

On failure, t_errno may be set to one of the following:

[TBADF]

The specified file descriptor does not refer to a transport endpoint.

[TNOSTRUCTYPE]

For XTI, an incorrect value was specified in the struct_type argument.

[TSYSERR]

A system error has occurred during execution of this function. The following conditions accompany this error:

t_errno errno Cause of error

TSYSERR not set Device or system failure

TSYSERR EINVAL struct_type out of range, or internal error

TSYSERR ENOMEM Memory could not be allocated for specified struct_type request

t_errno	errno	Cause of error
TSYSERR	not set	Device or system failure
TSYSERR	EINVAL	struct_type out of range, or internal error
TSYSERR	ENOMEM	Memory could not be allocated for specified struct_type request

Standards conformance

t_alloc is conformant with:

AT&T SVID Issue 3 ;
X/Open CAE Specification, Networking Services, Issue 4, 1994. ;
and Intel386 Binary Compatibility Specification, Edition 2 (iBCSe2) .