1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This module exports the functions:
4 *
5 *     'int set_selection_user(struct tiocl_selection __user *,
6 *			       struct tty_struct *)'
7 *     'int set_selection_kernel(struct tiocl_selection *, struct tty_struct *)'
8 *     'void clear_selection(void)'
9 *     'int paste_selection(struct tty_struct *)'
10 *     'int sel_loadlut(u32 __user *)'
11 *
12 * Now that /dev/vcs exists, most of this can disappear again.
13 */
14
15#include <linux/module.h>
16#include <linux/tty.h>
17#include <linux/sched.h>
18#include <linux/mm.h>
19#include <linux/mutex.h>
20#include <linux/slab.h>
21#include <linux/types.h>
22
23#include <linux/uaccess.h>
24
25#include <linux/kbd_kern.h>
26#include <linux/vt_kern.h>
27#include <linux/consolemap.h>
28#include <linux/selection.h>
29#include <linux/tiocl.h>
30#include <linux/console.h>
31#include <linux/tty_flip.h>
32
33#include <linux/sched/signal.h>
34
35/* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
36#define is_space_on_vt(c)	((c) == ' ')
37
38/* FIXME: all this needs locking */
39static struct vc_selection {
40	struct mutex lock;
41	struct vc_data *cons;			/* must not be deallocated */
42	char *buffer;
43	unsigned int buf_len;
44	volatile int start;			/* cleared by clear_selection */
45	int end;
46} vc_sel = {
47	.lock = __MUTEX_INITIALIZER(vc_sel.lock),
48	.start = -1,
49};
50
51/* clear_selection, highlight and highlight_pointer can be called
52   from interrupt (via scrollback/front) */
53
54/* set reverse video on characters s-e of console with selection. */
55static inline void highlight(const int s, const int e)
56{
57	invert_screen(vc_sel.cons, s, e-s+2, true);
58}
59
60/* use complementary color to show the pointer */
61static inline void highlight_pointer(const int where)
62{
63	complement_pos(vc_sel.cons, where);
64}
65
66static u32
67sel_pos(int n, bool unicode)
68{
69	if (unicode)
70		return screen_glyph_unicode(vc_sel.cons, n / 2);
71	return inverse_translate(vc_sel.cons, screen_glyph(vc_sel.cons, n),
72			false);
73}
74
75/**
76 * clear_selection - remove current selection
77 *
78 * Remove the current selection highlight, if any from the console holding the
79 * selection.
80 *
81 * Locking: The caller must hold the console lock.
82 */
83void clear_selection(void)
84{
85	highlight_pointer(-1); /* hide the pointer */
86	if (vc_sel.start != -1) {
87		highlight(vc_sel.start, vc_sel.end);
88		vc_sel.start = -1;
89	}
90}
91EXPORT_SYMBOL_GPL(clear_selection);
92
93bool vc_is_sel(const struct vc_data *vc)
94{
95	return vc == vc_sel.cons;
96}
97
98/*
99 * User settable table: what characters are to be considered alphabetic?
100 * 128 bits. Locked by the console lock.
101 */
102static u32 inwordLut[]={
103  0x00000000, /* control chars     */
104  0x03FFE000, /* digits and "-./"  */
105  0x87FFFFFE, /* uppercase and '_' */
106  0x07FFFFFE, /* lowercase         */
107};
108
109static inline int inword(const u32 c)
110{
111	return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
112}
113
114/**
115 * sel_loadlut() - load the LUT table
116 * @lut: user table
117 *
118 * Load the LUT table from user space. Make a temporary copy so a partial
119 * update doesn't make a mess.
120 *
121 * Locking: The console lock is acquired.
122 */
123int sel_loadlut(u32 __user *lut)
124{
125	u32 tmplut[ARRAY_SIZE(inwordLut)];
126
127	if (copy_from_user(tmplut, lut, sizeof(inwordLut)))
128		return -EFAULT;
129
130	console_lock();
131	memcpy(inwordLut, tmplut, sizeof(inwordLut));
132	console_unlock();
133
134	return 0;
135}
136
137/* does screen address p correspond to character at LH/RH edge of screen? */
138static inline int atedge(const int p, int size_row)
139{
140	return (!(p % size_row)	|| !((p + 2) % size_row));
141}
142
143/* stores the char in UTF8 and returns the number of bytes used (1-4) */
144static int store_utf8(u32 c, char *p)
145{
146	if (c < 0x80) {
147		/*  0******* */
148		p[0] = c;
149		return 1;
150	} else if (c < 0x800) {
151		/* 110***** 10****** */
152		p[0] = 0xc0 | (c >> 6);
153		p[1] = 0x80 | (c & 0x3f);
154		return 2;
155	} else if (c < 0x10000) {
156		/* 1110**** 10****** 10****** */
157		p[0] = 0xe0 | (c >> 12);
158		p[1] = 0x80 | ((c >> 6) & 0x3f);
159		p[2] = 0x80 | (c & 0x3f);
160		return 3;
161	} else if (c < 0x110000) {
162		/* 11110*** 10****** 10****** 10****** */
163		p[0] = 0xf0 | (c >> 18);
164		p[1] = 0x80 | ((c >> 12) & 0x3f);
165		p[2] = 0x80 | ((c >> 6) & 0x3f);
166		p[3] = 0x80 | (c & 0x3f);
167		return 4;
168	} else {
169		/* outside Unicode, replace with U+FFFD */
170		p[0] = 0xef;
171		p[1] = 0xbf;
172		p[2] = 0xbd;
173		return 3;
174	}
175}
176
177/**
178 * set_selection_user - set the current selection.
179 * @sel: user selection info
180 * @tty: the console tty
181 *
182 * Invoked by the ioctl handle for the vt layer.
183 *
184 * Locking: The entire selection process is managed under the console_lock.
185 * It's a lot under the lock but its hardly a performance path.
186 */
187int set_selection_user(const struct tiocl_selection __user *sel,
188		       struct tty_struct *tty)
189{
190	struct tiocl_selection v;
191
192	if (copy_from_user(&v, sel, sizeof(*sel)))
193		return -EFAULT;
194
195	return set_selection_kernel(&v, tty);
196}
197
198static int vc_selection_store_chars(struct vc_data *vc, bool unicode)
199{
200	char *bp, *obp;
201	unsigned int i;
202
203	/* Allocate a new buffer before freeing the old one ... */
204	/* chars can take up to 4 bytes with unicode */
205	bp = kmalloc_array((vc_sel.end - vc_sel.start) / 2 + 1, unicode ? 4 : 1,
206			   GFP_KERNEL | __GFP_NOWARN);
207	if (!bp) {
208		printk(KERN_WARNING "selection: kmalloc() failed\n");
209		clear_selection();
210		return -ENOMEM;
211	}
212	kfree(vc_sel.buffer);
213	vc_sel.buffer = bp;
214
215	obp = bp;
216	for (i = vc_sel.start; i <= vc_sel.end; i += 2) {
217		u32 c = sel_pos(i, unicode);
218		if (unicode)
219			bp += store_utf8(c, bp);
220		else
221			*bp++ = c;
222		if (!is_space_on_vt(c))
223			obp = bp;
224		if (!((i + 2) % vc->vc_size_row)) {
225			/* strip trailing blanks from line and add newline,
226			   unless non-space at end of line. */
227			if (obp != bp) {
228				bp = obp;
229				*bp++ = '\r';
230			}
231			obp = bp;
232		}
233	}
234	vc_sel.buf_len = bp - vc_sel.buffer;
235
236	return 0;
237}
238
239static int vc_do_selection(struct vc_data *vc, unsigned short mode, int ps,
240		int pe)
241{
242	int new_sel_start, new_sel_end, spc;
243	bool unicode = vt_do_kdgkbmode(fg_console) == K_UNICODE;
244
245	switch (mode) {
246	case TIOCL_SELCHAR:	/* character-by-character selection */
247		new_sel_start = ps;
248		new_sel_end = pe;
249		break;
250	case TIOCL_SELWORD:	/* word-by-word selection */
251		spc = is_space_on_vt(sel_pos(ps, unicode));
252		for (new_sel_start = ps; ; ps -= 2) {
253			if ((spc && !is_space_on_vt(sel_pos(ps, unicode))) ||
254			    (!spc && !inword(sel_pos(ps, unicode))))
255				break;
256			new_sel_start = ps;
257			if (!(ps % vc->vc_size_row))
258				break;
259		}
260
261		spc = is_space_on_vt(sel_pos(pe, unicode));
262		for (new_sel_end = pe; ; pe += 2) {
263			if ((spc && !is_space_on_vt(sel_pos(pe, unicode))) ||
264			    (!spc && !inword(sel_pos(pe, unicode))))
265				break;
266			new_sel_end = pe;
267			if (!((pe + 2) % vc->vc_size_row))
268				break;
269		}
270		break;
271	case TIOCL_SELLINE:	/* line-by-line selection */
272		new_sel_start = rounddown(ps, vc->vc_size_row);
273		new_sel_end = rounddown(pe, vc->vc_size_row) +
274			vc->vc_size_row - 2;
275		break;
276	case TIOCL_SELPOINTER:
277		highlight_pointer(pe);
278		return 0;
279	default:
280		return -EINVAL;
281	}
282
283	/* remove the pointer */
284	highlight_pointer(-1);
285
286	/* select to end of line if on trailing space */
287	if (new_sel_end > new_sel_start &&
288		!atedge(new_sel_end, vc->vc_size_row) &&
289		is_space_on_vt(sel_pos(new_sel_end, unicode))) {
290		for (pe = new_sel_end + 2; ; pe += 2)
291			if (!is_space_on_vt(sel_pos(pe, unicode)) ||
292			    atedge(pe, vc->vc_size_row))
293				break;
294		if (is_space_on_vt(sel_pos(pe, unicode)))
295			new_sel_end = pe;
296	}
297	if (vc_sel.start == -1)	/* no current selection */
298		highlight(new_sel_start, new_sel_end);
299	else if (new_sel_start == vc_sel.start)
300	{
301		if (new_sel_end == vc_sel.end)	/* no action required */
302			return 0;
303		else if (new_sel_end > vc_sel.end)	/* extend to right */
304			highlight(vc_sel.end + 2, new_sel_end);
305		else				/* contract from right */
306			highlight(new_sel_end + 2, vc_sel.end);
307	}
308	else if (new_sel_end == vc_sel.end)
309	{
310		if (new_sel_start < vc_sel.start) /* extend to left */
311			highlight(new_sel_start, vc_sel.start - 2);
312		else				/* contract from left */
313			highlight(vc_sel.start, new_sel_start - 2);
314	}
315	else	/* some other case; start selection from scratch */
316	{
317		clear_selection();
318		highlight(new_sel_start, new_sel_end);
319	}
320	vc_sel.start = new_sel_start;
321	vc_sel.end = new_sel_end;
322
323	return vc_selection_store_chars(vc, unicode);
324}
325
326static int vc_selection(struct vc_data *vc, struct tiocl_selection *v,
327		struct tty_struct *tty)
328{
329	int ps, pe;
330
331	poke_blanked_console();
332
333	if (v->sel_mode == TIOCL_SELCLEAR) {
334		/* useful for screendump without selection highlights */
335		clear_selection();
336		return 0;
337	}
338
339	v->xs = min_t(u16, v->xs - 1, vc->vc_cols - 1);
340	v->ys = min_t(u16, v->ys - 1, vc->vc_rows - 1);
341	v->xe = min_t(u16, v->xe - 1, vc->vc_cols - 1);
342	v->ye = min_t(u16, v->ye - 1, vc->vc_rows - 1);
343
344	if (mouse_reporting() && (v->sel_mode & TIOCL_SELMOUSEREPORT)) {
345		mouse_report(tty, v->sel_mode & TIOCL_SELBUTTONMASK, v->xs,
346			     v->ys);
347		return 0;
348	}
349
350	ps = v->ys * vc->vc_size_row + (v->xs << 1);
351	pe = v->ye * vc->vc_size_row + (v->xe << 1);
352	if (ps > pe)	/* make vc_sel.start <= vc_sel.end */
353		swap(ps, pe);
354
355	if (vc_sel.cons != vc) {
356		clear_selection();
357		vc_sel.cons = vc;
358	}
359
360	return vc_do_selection(vc, v->sel_mode, ps, pe);
361}
362
363int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
364{
365	int ret;
366
367	mutex_lock(&vc_sel.lock);
368	console_lock();
369	ret = vc_selection(vc_cons[fg_console].d, v, tty);
370	console_unlock();
371	mutex_unlock(&vc_sel.lock);
372
373	return ret;
374}
375EXPORT_SYMBOL_GPL(set_selection_kernel);
376
377/* Insert the contents of the selection buffer into the
378 * queue of the tty associated with the current console.
379 * Invoked by ioctl().
380 *
381 * Locking: called without locks. Calls the ldisc wrongly with
382 * unsafe methods,
383 */
384int paste_selection(struct tty_struct *tty)
385{
386	struct vc_data *vc = tty->driver_data;
387	int	pasted = 0;
388	size_t count;
389	struct  tty_ldisc *ld;
390	DECLARE_WAITQUEUE(wait, current);
391	int ret = 0;
392
393	console_lock();
394	poke_blanked_console();
395	console_unlock();
396
397	ld = tty_ldisc_ref_wait(tty);
398	if (!ld)
399		return -EIO;	/* ldisc was hung up */
400	tty_buffer_lock_exclusive(&vc->port);
401
402	add_wait_queue(&vc->paste_wait, &wait);
403	mutex_lock(&vc_sel.lock);
404	while (vc_sel.buffer && vc_sel.buf_len > pasted) {
405		set_current_state(TASK_INTERRUPTIBLE);
406		if (signal_pending(current)) {
407			ret = -EINTR;
408			break;
409		}
410		if (tty_throttled(tty)) {
411			mutex_unlock(&vc_sel.lock);
412			schedule();
413			mutex_lock(&vc_sel.lock);
414			continue;
415		}
416		__set_current_state(TASK_RUNNING);
417		count = vc_sel.buf_len - pasted;
418		count = tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted, NULL,
419					      count);
420		pasted += count;
421	}
422	mutex_unlock(&vc_sel.lock);
423	remove_wait_queue(&vc->paste_wait, &wait);
424	__set_current_state(TASK_RUNNING);
425
426	tty_buffer_unlock_exclusive(&vc->port);
427	tty_ldisc_deref(ld);
428	return ret;
429}
430EXPORT_SYMBOL_GPL(paste_selection);
431