char *t_alloc(int fd, int struct_type, int fields);
t_alloc 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 can be one of the following:
T_BIND /* struct t_bind */ T_OPTMGMT /* struct t_optmgmt */ T_CALL /* struct t_call */ 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.
netbufis described in intro(NET). 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 as returned in the
infoargument of t_open or t_getinfo. The relevant fields of the info argument are described in the following list. The
fieldsargument specifies which buffers to allocate, where the argument is the bitwise-OR of any of the following:
addrfield of the t_bind, t_call, t_unitdata, or t_uderr structures.
optfield of the t_optmgmt, t_call, t_unitdata, or t_uderr structures.
udatafield of the t_call, t_discon, or t_unitdata structures.
lenfield to 0 and initialize the
netbufin intro(NET) for description of
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 and t_getinfo. Thus, fd 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, or -2, t_alloc will be unable to determine the size of the buffer to allocate and will fail with t_errno set to TSYSERR, unless when T_ALL is specified, in which case unsupported fields are ignored silently.
For any field not specified in fields, buf will be set to NULL and maxlen will be set to 0. If the fields argument is set to T_ALL, fields that are not supported by the transport provider specified by fd are not allocated.
Buffers and memory that have been allocated with t_alloc may be freed with t_free.