t_alloc() — Allocate a library structure
Standards
Standards / Extensions | C or C++ | Dependencies |
---|---|---|
XPG4.2 | both |
Format
#define _XOPEN_SOURCE_EXTENDED 1
#include <xti.h>
char *t_alloc(int fd, int struct_type, int fields);
General description
Dynamically allocates memory for the various transport function argument structures as specified below. t_alloc() allocates memory for the specified structure, and memory for buffers referenced by the structure.
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.- 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 the transport provider specified by fd will not be allocated.
For each relevant field specified in fields, t_alloc() allocates memory for the buffer associated with the field, and initializes the len field to zero and the buf pointer and maxlen field accordingly. Irrelevant or unknown values passed in fields are ignored. Since the length of the buffer allocated will be based on the same size information that is returned to the user on a call to t_open() and 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() 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 the NULL pointer and len and maxlen will be set to zero.
Use of t_alloc() to allocate structures helps ensure the compatibility of user programs with future releases of the transport interface functions.
Valid states: All - except for T_UNINIT
Returned value
If successful, t_alloc() returns a pointer to the newly allocated structure.
- Error Code
- Description
- TBADF
- The specified file descriptor does not refer to a transport endpoint.
- TNOSTRUCTYPE
- Unsupported struct_type requested. This can include a request for a structure type which is inconsistent with the transport provider type specified, that is, connection-oriented or connectionless.
- TPROTO
- This error indicates that a communication problem has been detected between XTI and the transport provider for which there is no other suitable XTI (t_errno).
- TSYSERR
- A system error has occurred during execution of this function.