Data Structure

SunOS 5.x reserves the right to change ptem(7M)'s internal implementation. This structure should be relevant only to people wanting to change the module.

Each instantiation of ptem(7M) is associated with a local area. These data are held in a structure called ptem that has the following format:

struct ptem
{
	long cflags;							/* copy of c_flags */
	mblk_t *dack_ptr;							/* pointer to preallocated msg blk
									used to send disconnect */
	queue_t *q_ptr;							/* pointer to ptem's read queue */
	struct winsize wsz;				/*struct to hold windowing info*/
	unsigned short state; /* state of ptem entry */
};

When ptem(7M) is pushed onto the slave side Stream, a search of the ptem structure is made for a free entry (state is not set to INUSE). The c_cflags of the termio(7I) structure and the windowing variables are stored in cflags and wsz respectively. The dack_ptr is a pointer to a message block used to send a zero-length message whenever a hang-up occurs on the slave side.