text: // SPDX-License-Identifier: GPL-2.0
  /*
   * This module exports the functions:
   *
   *     'int set_selection_user(struct tiocl_selection __user *,
   *			       struct tty_struct *)'
   *     'int set_selection_kernel(struct tiocl_selection *, struct tty_struct *)'
   *     'void clear_selection(void)'
   *     'int paste_selection(struct tty_struct *)'
   *     'int sel_loadlut(char __user *)'
   *
   * Now that /dev/vcs exists, most of this can disappear again.
   */
  
  #include <linux/module.h>
  #include <linux/tty.h>
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  
  #include <linux/uaccess.h>
  
  #include <linux/kbd_kern.h>
  #include <linux/vt_kern.h>
  #include <linux/consolemap.h>
  #include <linux/selection.h>
  #include <linux/tiocl.h>
  #include <linux/console.h>
  #include <linux/tty_flip.h>
  
  #include <linux/sched/signal.h>
  
  /* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
  #define isspace(c)	((c) == ' ')
  
  extern void poke_blanked_console(void);
  
  /* FIXME: all this needs locking */
  /* Variables for selection control. */
  /* Use a dynamic buffer, instead of static (Dec 1994) */
  struct vc_data *sel_cons;		/* must not be deallocated */
  static int use_unicode;
  static volatile int sel_start = -1; 	/* cleared by clear_selection */
  static int sel_end;
  static int sel_buffer_lth;
  static char *sel_buffer;
  
  /* clear_selection, highlight and highlight_pointer can be called
     from interrupt (via scrollback/front) */
  
  /* set reverse video on characters s-e of console with selection. */
  static inline void highlight(const int s, const int e)
  {
  	invert_screen(sel_cons, s, e-s+2, 1);
  }
  
  /* use complementary color to show the pointer */
  static inline void highlight_pointer(const int where)
  {
  	complement_pos(sel_cons, where);
  }
  
  static u32
  sel_pos(int n)
  {
  	if (use_unicode)
  		return screen_glyph_unicode(sel_cons, n / 2);
  	return inverse_translate(sel_cons, screen_glyph(sel_cons, n),
  				0);
  }
  
  /**
   *	clear_selection		-	remove current selection
   *
   *	Remove the current selection highlight, if any from the console
   *	holding the selection. The caller must hold the console lock.
   */
  void clear_selection(void)
  {
  	highlight_pointer(-1); /* hide the pointer */
  	if (sel_start != -1) {
  		highlight(sel_start, sel_end);
  		sel_start = -1;
  	}
  }
  EXPORT_SYMBOL_GPL(clear_selection);
  
  /*
   * User settable table: what characters are to be considered alphabetic?
   * 128 bits. Locked by the console lock.
   */
  static u32 inwordLut[]={
    0x00000000, /* control chars     */
    0x03FFE000, /* digits and "-./"  */
    0x87FFFFFE, /* uppercase and '_' */
    0x07FFFFFE, /* lowercase         */
  };
  
  static inline int inword(const u32 c)
  {
  	return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
  }
  
  /**
   *	set loadlut		-	load the LUT table
   *	@p: user table
   *
   *	Load the LUT table from user space. The caller must hold the console
   *	lock. Make a temporary copy so a partial update doesn't make a mess.
   */
  int sel_loadlut(char __user *p)
  {
  	u32 tmplut[ARRAY_SIZE(inwordLut)];
  	if (copy_from_user(tmplut, (u32 __user *)(p+4), sizeof(inwordLut)))
  		return -EFAULT;
  	memcpy(inwordLut, tmplut, sizeof(inwordLut));
  	return 0;
  }
  
  /* does screen address p correspond to character at LH/RH edge of screen? */
  static inline int atedge(const int p, int size_row)
  {
  	return (!(p % size_row)	|| !((p + 2) % size_row));
  }
  
  /* stores the char in UTF8 and returns the number of bytes used (1-4) */
  static int store_utf8(u32 c, char *p)
  {
  	if (c < 0x80) {
  		/*  0******* */
  		p[0] = c;
  		return 1;
  	} else if (c < 0x800) {
  		/* 110***** 10****** */
  		p[0] = 0xc0 | (c >> 6);
  		p[1] = 0x80 | (c & 0x3f);
  		return 2;
  	} else if (c < 0x10000) {
  		/* 1110**** 10****** 10****** */
  		p[0] = 0xe0 | (c >> 12);
  		p[1] = 0x80 | ((c >> 6) & 0x3f);
  		p[2] = 0x80 | (c & 0x3f);
  		return 3;
  	} else if (c < 0x110000) {
  		/* 11110*** 10****** 10****** 10****** */
  		p[0] = 0xf0 | (c >> 18);
  		p[1] = 0x80 | ((c >> 12) & 0x3f);
  		p[2] = 0x80 | ((c >> 6) & 0x3f);
  		p[3] = 0x80 | (c & 0x3f);
  		return 4;
  	} else {
  		/* outside Unicode, replace with U+FFFD */
  		p[0] = 0xef;
  		p[1] = 0xbf;
  		p[2] = 0xbd;
  		return 3;
  	}
  }
  
  /**
   *	set_selection_user	-	set the current selection.
   *	@sel: user selection info
   *	@tty: the console tty
   *
   *	Invoked by the ioctl handle for the vt layer.
   *
   *	The entire selection process is managed under the console_lock. It's
   *	 a lot under the lock but its hardly a performance path
   */
  int set_selection_user(const struct tiocl_selection __user *sel,
  		       struct tty_struct *tty)
  {
  	struct tiocl_selection v;
  
  	if (copy_from_user(&v, sel, sizeof(*sel)))
  		return -EFAULT;
  
  	return set_selection_kernel(&v, tty);
  }
  
  int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
  {
  	struct vc_data *vc = vc_cons[fg_console].d;
  	int new_sel_start, new_sel_end, spc;
  	char *bp, *obp;
  	int i, ps, pe, multiplier;
  	u32 c;
  	int mode;
  
  	poke_blanked_console();
  
  	v->xs = min_t(u16, v->xs - 1, vc->vc_cols - 1);
  	v->ys = min_t(u16, v->ys - 1, vc->vc_rows - 1);
  	v->xe = min_t(u16, v->xe - 1, vc->vc_cols - 1);
  	v->ye = min_t(u16, v->ye - 1, vc->vc_rows - 1);
  	ps = v->ys * vc->vc_size_row + (v->xs << 1);
  	pe = v->ye * vc->vc_size_row + (v->xe << 1);
  
  	if (v->sel_mode == TIOCL_SELCLEAR) {
  		/* useful for screendump without selection highlights */
  		clear_selection();
  		return 0;
  	}
  
  	if (mouse_reporting() && (v->sel_mode & TIOCL_SELMOUSEREPORT)) {
  		mouse_report(tty, v->sel_mode & TIOCL_SELBUTTONMASK, v->xs,
  			     v->ys);
  		return 0;
  	}
  
  	if (ps > pe)	/* make sel_start <= sel_end */
  		swap(ps, pe);
  
  	if (sel_cons != vc_cons[fg_console].d) {
  		clear_selection();
  		sel_cons = vc_cons[fg_console].d;
  	}
  	mode = vt_do_kdgkbmode(fg_console);
  	if (mode == K_UNICODE)
  		use_unicode = 1;
  	else
  		use_unicode = 0;
  
  	switch (v->sel_mode)
  	{
  		case TIOCL_SELCHAR:	/* character-by-character selection */
  			new_sel_start = ps;
  			new_sel_end = pe;
  			break;
  		case TIOCL_SELWORD:	/* word-by-word selection */
  			spc = isspace(sel_pos(ps));
  			for (new_sel_start = ps; ; ps -= 2)
  			{
  				if ((spc && !isspace(sel_pos(ps))) ||
  				    (!spc && !inword(sel_pos(ps))))
  					break;
  				new_sel_start = ps;
  				if (!(ps % vc->vc_size_row))
  					break;
  			}
  			spc = isspace(sel_pos(pe));
  			for (new_sel_end = pe; ; pe += 2)
  			{
  				if ((spc && !isspace(sel_pos(pe))) ||
  				    (!spc && !inword(sel_pos(pe))))
  					break;
  				new_sel_end = pe;
  				if (!((pe + 2) % vc->vc_size_row))
  					break;
  			}
  			break;
  		case TIOCL_SELLINE:	/* line-by-line selection */
  			new_sel_start = ps - ps % vc->vc_size_row;
  			new_sel_end = pe + vc->vc_size_row
  				    - pe % vc->vc_size_row - 2;
  			break;
  		case TIOCL_SELPOINTER:
  			highlight_pointer(pe);
  			return 0;
  		default:
  			return -EINVAL;
  	}
  
  	/* remove the pointer */
  	highlight_pointer(-1);
  
  	/* select to end of line if on trailing space */
  	if (new_sel_end > new_sel_start &&
  		!atedge(new_sel_end, vc->vc_size_row) &&
  		isspace(sel_pos(new_sel_end))) {
  		for (pe = new_sel_end + 2; ; pe += 2)
  			if (!isspace(sel_pos(pe)) ||
  			    atedge(pe, vc->vc_size_row))
  				break;
  		if (isspace(sel_pos(pe)))
  			new_sel_end = pe;
  	}
  	if (sel_start == -1)	/* no current selection */
  		highlight(new_sel_start, new_sel_end);
  	else if (new_sel_start == sel_start)
  	{
  		if (new_sel_end == sel_end)	/* no action required */
  			return 0;
  		else if (new_sel_end > sel_end)	/* extend to right */
  			highlight(sel_end + 2, new_sel_end);
  		else				/* contract from right */
  			highlight(new_sel_end + 2, sel_end);
  	}
  	else if (new_sel_end == sel_end)
  	{
  		if (new_sel_start < sel_start)	/* extend to left */
  			highlight(new_sel_start, sel_start - 2);
  		else				/* contract from left */
  			highlight(sel_start, new_sel_start - 2);
  	}
  	else	/* some other case; start selection from scratch */
  	{
  		clear_selection();
  		highlight(new_sel_start, new_sel_end);
  	}
  	sel_start = new_sel_start;
  	sel_end = new_sel_end;
  
  	/* Allocate a new buffer before freeing the old one ... */
  	multiplier = use_unicode ? 4 : 1;  /* chars can take up to 4 bytes */
  	bp = kmalloc_array((sel_end - sel_start) / 2 + 1, multiplier,
  			   GFP_KERNEL);
  	if (!bp) {
  		printk(KERN_WARNING "selection: kmalloc() failed\n");
  		clear_selection();
  		return -ENOMEM;
  	}
  	kfree(sel_buffer);
  	sel_buffer = bp;
  
  	obp = bp;
  	for (i = sel_start; i <= sel_end; i += 2) {
  		c = sel_pos(i);
  		if (use_unicode)
  			bp += store_utf8(c, bp);
  		else
  			*bp++ = c;
  		if (!isspace(c))
  			obp = bp;
  		if (! ((i + 2) % vc->vc_size_row)) {
  			/* strip trailing blanks from line and add newline,
  			   unless non-space at end of line. */
  			if (obp != bp) {
  				bp = obp;
  				*bp++ = '\r';
  			}
  			obp = bp;
  		}
  	}
  	sel_buffer_lth = bp - sel_buffer;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(set_selection_kernel);
  
  /* Insert the contents of the selection buffer into the
   * queue of the tty associated with the current console.
   * Invoked by ioctl().
   *
   * Locking: called without locks. Calls the ldisc wrongly with
   * unsafe methods,
   */
  int paste_selection(struct tty_struct *tty)
  {
  	struct vc_data *vc = tty->driver_data;
  	int	pasted = 0;
  	unsigned int count;
  	struct  tty_ldisc *ld;
  	DECLARE_WAITQUEUE(wait, current);
  	int ret = 0;
  
  	console_lock();
  	poke_blanked_console();
  	console_unlock();
  
  	ld = tty_ldisc_ref_wait(tty);
  	if (!ld)
  		return -EIO;	/* ldisc was hung up */
  	tty_buffer_lock_exclusive(&vc->port);
  
  	add_wait_queue(&vc->paste_wait, &wait);
  	while (sel_buffer && sel_buffer_lth > pasted) {
  		set_current_state(TASK_INTERRUPTIBLE);
  		if (signal_pending(current)) {
  			ret = -EINTR;
  			break;
  		}
  		if (tty_throttled(tty)) {
  			schedule();
  			continue;
  		}
  		__set_current_state(TASK_RUNNING);
  		count = sel_buffer_lth - pasted;
  		count = tty_ldisc_receive_buf(ld, sel_buffer + pasted, NULL,
  					      count);
  		pasted += count;
  	}
  	remove_wait_queue(&vc->paste_wait, &wait);
  	__set_current_state(TASK_RUNNING);
  
  	tty_buffer_unlock_exclusive(&vc->port);
  	tty_ldisc_deref(ld);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(paste_selection);
  