1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
45  * The previous design of the TTY layer offered the so-called clists.
61 	if (to->to_end == 0) {						\
62 		tob->tob_next = to->to_firstblock;			\
63 		to->to_firstblock = tob;				\
65 		tob->tob_next = to->to_lastblock->tob_next;		\
66 		to->to_lastblock->tob_next = tob;			\
68 	to->to_nblocks++;						\
72 	to->to_firstblock = to->to_firstblock->tob_next;		\
73 	to->to_nblocks--;						\
77 	if (to->to_quota <= to->to_nblocks)				\
87 	to->to_begin = 0;  in ttyoutq_flush()
88 	to->to_end = 0;  in ttyoutq_flush()
96 	to->to_quota = howmany(size, TTYOUTQ_DATASIZE);  in ttyoutq_setsize()
98 	while (to->to_quota > to->to_nblocks) {  in ttyoutq_setsize()
129 	to->to_quota = 0;  in ttyoutq_free()
131 	while ((tob = to->to_firstblock) != NULL) {  in ttyoutq_free()
136 	MPASS(to->to_nblocks == 0);  in ttyoutq_free()
149 		if (to->to_begin == to->to_end)  in ttyoutq_read()
151 		tob = to->to_firstblock;  in ttyoutq_read()
157 		 * - The write pointer  in ttyoutq_read()
158 		 * - The blocksize - we can't read beyond the block  in ttyoutq_read()
159 		 * - The end address if we could perform the full read  in ttyoutq_read()
161 		cbegin = to->to_begin;  in ttyoutq_read()
162 		cend = MIN(MIN(to->to_end, to->to_begin + len),  in ttyoutq_read()
164 		clen = cend - cbegin;  in ttyoutq_read()
166 		/* Copy the data out of the buffers. */  in ttyoutq_read()
167 		memcpy(cbuf, tob->tob_data + cbegin, clen);  in ttyoutq_read()
169 		len -= clen;  in ttyoutq_read()
171 		if (cend == to->to_end) {  in ttyoutq_read()
173 			to->to_begin = 0;  in ttyoutq_read()
174 			to->to_end = 0;  in ttyoutq_read()
176 			/* Read the block until the end. */  in ttyoutq_read()
178 			to->to_begin = 0;  in ttyoutq_read()
179 			to->to_end -= TTYOUTQ_DATASIZE;  in ttyoutq_read()
182 			/* Read the block partially. */  in ttyoutq_read()
183 			to->to_begin += clen;  in ttyoutq_read()
187 	return (cbuf - (char *)buf);  in ttyoutq_read()
192  * TTY drivers to directly copy data from the outq to userspace, instead
195  * We can only copy data directly if we need to read the entire block
196  * back to the user, because we temporarily remove the block from the
197  * queue. Otherwise we need to copy it to a temporary buffer first, to
204 	while (uio->uio_resid > 0) {  in ttyoutq_read_uio()
210 		if (to->to_begin == to->to_end)  in ttyoutq_read_uio()
212 		tob = to->to_firstblock;  in ttyoutq_read_uio()
218 		 * - The write pointer  in ttyoutq_read_uio()
219 		 * - The blocksize - we can't read beyond the block  in ttyoutq_read_uio()
220 		 * - The end address if we could perform the full read  in ttyoutq_read_uio()
222 		cbegin = to->to_begin;  in ttyoutq_read_uio()
223 		cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid),  in ttyoutq_read_uio()
225 		clen = cend - cbegin;  in ttyoutq_read_uio()
229 		 * - We need to read the block until the end.  in ttyoutq_read_uio()
230 		 * - We don't need to read the block until the end, but  in ttyoutq_read_uio()
232 		 *   the write pointer to a new block.  in ttyoutq_read_uio()
234 		if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) {  in ttyoutq_read_uio()
236 			 * Fast path: zero copy. Remove the first block,  in ttyoutq_read_uio()
240 			to->to_begin = 0;  in ttyoutq_read_uio()
241 			if (to->to_end <= TTYOUTQ_DATASIZE)  in ttyoutq_read_uio()
242 				to->to_end = 0;  in ttyoutq_read_uio()
244 				to->to_end -= TTYOUTQ_DATASIZE;  in ttyoutq_read_uio()
246 			/* Temporary unlock and copy the data to userspace. */  in ttyoutq_read_uio()
248 			error = uiomove(tob->tob_data + cbegin, clen, uio);  in ttyoutq_read_uio()
251 			/* Block can now be readded to the list. */  in ttyoutq_read_uio()
254 			char ob[TTYOUTQ_DATASIZE - 1];  in ttyoutq_read_uio()
259 			memcpy(ob, tob->tob_data + cbegin, clen);  in ttyoutq_read_uio()
260 			to->to_begin += clen;  in ttyoutq_read_uio()
261 			MPASS(to->to_begin < TTYOUTQ_DATASIZE);  in ttyoutq_read_uio()
263 			/* Temporary unlock and copy the data to userspace. */  in ttyoutq_read_uio()
285 		boff = to->to_end % TTYOUTQ_DATASIZE;  in ttyoutq_write()
287 		if (to->to_end == 0) {  in ttyoutq_write()
289 			MPASS(to->to_begin == 0);  in ttyoutq_write()
290 			tob = to->to_firstblock;  in ttyoutq_write()
295 			to->to_lastblock = tob;  in ttyoutq_write()
297 			/* We reached the end of this block on last write. */  in ttyoutq_write()
298 			tob = to->to_lastblock->tob_next;  in ttyoutq_write()
303 			to->to_lastblock = tob;  in ttyoutq_write()
305 			tob = to->to_lastblock;  in ttyoutq_write()
308 		/* Don't copy more than was requested. */  in ttyoutq_write()
309 		l = MIN(nbytes, TTYOUTQ_DATASIZE - boff);  in ttyoutq_write()
311 		memcpy(tob->tob_data + boff, cbuf, l);  in ttyoutq_write()
314 		nbytes -= l;  in ttyoutq_write()
315 		to->to_end += l;  in ttyoutq_write()
318 	return (cbuf - (const char *)buf);  in ttyoutq_write()
327 		return (-1);  in ttyoutq_write_nofrag()