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man pages section 3: Basic Library Functions

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Updated: Wednesday, July 27, 2022



t_free - free a library structure


#include <xti.h>

int t_free(void *ptr, int struct_type);


This routine is part of the XTI interfaces which evolved from the TLI interfaces. XTI represents the future evolution of these interfaces. However, TLI interfaces are supported for compatibility. When using a TLI routine that has the same name as an XTI routine, the tiuser.h header file must be used. Refer to the TLI COMPATIBILITY section for a description of differences between the two interfaces.

The t_free() function frees memory previously allocated by t_alloc(3C). This function will free memory for the specified structure, and will also free memory for buffers referenced by the structure.

The argument ptr points to one of the seven structure types described for t_alloc(3C), and struct_type identifies the type of that structure which must 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 is used as an argument to one or more transport functions.

The function t_free() will check the addr, opt and udata fields of the given structure, as appropriate, and free the buffers pointed to by the buf field of the netbuf structure. If buf is a null pointer, t_free() will not attempt to free memory. After all buffers are freed, t_free() will free the memory associated with the structure pointed to by ptr.

Undefined results will occur if ptr or any of the buf pointers points to a block of memory that was not previously allocated by t_alloc(3C).

Return Values

Upon successful completion, a value of 0 is returned. Otherwise, a value of –1 is returned and t_errno is set to indicate an error.


ALL - apart from T_UNINIT.


On failure, t_errno is set to the following:


Unsupported struct_type requested.


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


A system error has occurred during execution of this function.


The XTI and TLI interface definitions have common names but use different header files. This, and other semantic differences between the two interfaces are described in the subsections below.

Interface Header

The XTI interfaces use the header file, xti.h. TLI interfaces should not use this header. They should use the header:

#include <tiuser.h> 

Error Description Values

The t_errno value that can be set by the XTI interface and cannot be set by the TLI interface is:



See attributes(7) for descriptions of the following attributes:

MT Level

See Also

t_alloc(3C), attributes(7)