NAME

t_alloc() − allocate a library structure

SYNOPSIS

#include <xti.h> (for X/OPEN Transport Interface - XTI)

or

#include <tiuser.h> (for Transport Layer Interface - TLI)

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 must be one of the following:

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.  For each field of this type, the user may specify that the buffer for that field should be allocated as well.  The length of the buffer allocated will be equal to or greater than the appropriate size returned in the info argument of t_open() or t_getinfo().  The relevant fields of the info argument are described in the following list.  The fields argument specifies which buffer to allocate, 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.  Fields which are not supported by e transport provider specified by fd will not be allocated ( info values are <= 0). 

For each field specified in fields, t_alloc() will allocate memory for the buffer associated with the field, and initialize the len field to zero and the buf pointer and maxlen field accordingly.  Since the length of the buffer allocated will be based on the same size information that is returned to the user on t_open() or t_getinfo(), fd must refer to the transport endpoint through which the newly allocated structure will be passed.  In this way the appropriate size information can be accessed.  If the size value associated with any specified field is -1 or -2 ( see t_open(3) or t_getinfo(3)), 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 a null pointer 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 functions. 

Valid States

All - apart from T_UNINIT

RETURN VALUE

Upon successful completion, t_alloc() returns a pointer to the newly allocated structure.  On failure, a null pointer is returned. 

ERRORS

On failure, t_errno is set to one of the following:

­[TBADF] fd The specified endpoint identifier does not refer to a transport endpoint

­[TSYSERR] A system error has occurred during execution of this function. 

­[TPROTO] (XTI only) This error indicates that a communication problem has been detected between XTI and the transport provider for which there is no suitable XTI ( t_errno). 

­[TNOSTRUCTYPE] Unsupported struct_type requested.  This can include a request for a structure type which is inconsistent with the transport provider type specified, i.e., connection-oriented or connectionless. 

SEE ALSO

t_free(3), t_getinfo(3), t_open(3). 

STANDARDS CONFORMANCE

t_alloc(): SVID2, XPG3, XPG4

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996