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selection.c

/*
 * linux/drivers/char/selection.c
 *
 * This module exports the functions:
 *
 *     'int set_selection(struct tiocl_selection __user *, 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 <asm/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>

/* 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);

/* 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 u16
sel_pos(int n)
{
      return inverse_translate(sel_cons, screen_glyph(sel_cons, n),
                        use_unicode);
}

/* remove the current selection highlight, if any,
   from the console holding the selection. */
void
clear_selection(void) {
      highlight_pointer(-1); /* hide the pointer */
      if (sel_start != -1) {
            highlight(sel_start, sel_end);
            sel_start = -1;
      }
}

/*
 * User settable table: what characters are to be considered alphabetic?
 * 256 bits
 */
static u32 inwordLut[8]={
  0x00000000, /* control chars     */
  0x03FF0000, /* digits            */
  0x87FFFFFE, /* uppercase and '_' */
  0x07FFFFFE, /* lowercase         */
  0x00000000,
  0x00000000,
  0xFF7FFFFF, /* latin-1 accented letters, not multiplication sign */
  0xFF7FFFFF  /* latin-1 accented letters, not division sign */
};

static inline int inword(const u16 c) {
      return c > 0xff || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
}

/* set inwordLut contents. Invoked by ioctl(). */
int sel_loadlut(char __user *p)
{
      return copy_from_user(inwordLut, (u32 __user *)(p+4), 32) ? -EFAULT : 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));
}

/* constrain v such that v <= u */
static inline unsigned short limit(const unsigned short v, const unsigned short u)
{
      return (v > u) ? u : v;
}

/* stores the char in UTF8 and returns the number of bytes used (1-3) */
static int store_utf8(u16 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 {
            /* 1110**** 10****** 10****** */
            p[0] = 0xe0 | (c >> 12);
            p[1] = 0x80 | ((c >> 6) & 0x3f);
            p[2] = 0x80 | (c & 0x3f);
            return 3;
      }
}

/* set the current selection. Invoked by ioctl() or by kernel code. */
int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
{
      struct vc_data *vc = vc_cons[fg_console].d;
      int sel_mode, new_sel_start, new_sel_end, spc;
      char *bp, *obp;
      int i, ps, pe, multiplier;
      u16 c;
      struct kbd_struct *kbd = kbd_table + fg_console;

      poke_blanked_console();

      { unsigned short xs, ys, xe, ye;

        if (!access_ok(VERIFY_READ, sel, sizeof(*sel)))
            return -EFAULT;
        __get_user(xs, &sel->xs);
        __get_user(ys, &sel->ys);
        __get_user(xe, &sel->xe);
        __get_user(ye, &sel->ye);
        __get_user(sel_mode, &sel->sel_mode);
        xs--; ys--; xe--; ye--;
        xs = limit(xs, vc->vc_cols - 1);
        ys = limit(ys, vc->vc_rows - 1);
        xe = limit(xe, vc->vc_cols - 1);
        ye = limit(ye, vc->vc_rows - 1);
        ps = ys * vc->vc_size_row + (xs << 1);
        pe = ye * vc->vc_size_row + (xe << 1);

        if (sel_mode == TIOCL_SELCLEAR) {
            /* useful for screendump without selection highlights */
            clear_selection();
            return 0;
        }

        if (mouse_reporting() && (sel_mode & TIOCL_SELMOUSEREPORT)) {
            mouse_report(tty, sel_mode & TIOCL_SELBUTTONMASK, xs, ys);
            return 0;
        }
        }

      if (ps > pe)      /* make sel_start <= sel_end */
      {
            int tmp = ps;
            ps = pe;
            pe = tmp;
      }

      if (sel_cons != vc_cons[fg_console].d) {
            clear_selection();
            sel_cons = vc_cons[fg_console].d;
      }
      use_unicode = kbd && kbd->kbdmode == VC_UNICODE;

      switch (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 ? 3 : 1;  /* chars can take up to 3 bytes */
      bp = kmalloc((sel_end-sel_start)/2*multiplier+1, 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;
}

/* Insert the contents of the selection buffer into the
 * queue of the tty associated with the current console.
 * Invoked by ioctl().
 */
int paste_selection(struct tty_struct *tty)
{
      struct vc_data *vc = (struct vc_data *)tty->driver_data;
      int   pasted = 0;
      unsigned int count;
      struct  tty_ldisc *ld;
      DECLARE_WAITQUEUE(wait, current);

      acquire_console_sem();
      poke_blanked_console();
      release_console_sem();

      ld = tty_ldisc_ref_wait(tty);
      
      add_wait_queue(&vc->paste_wait, &wait);
      while (sel_buffer && sel_buffer_lth > pasted) {
            set_current_state(TASK_INTERRUPTIBLE);
            if (test_bit(TTY_THROTTLED, &tty->flags)) {
                  schedule();
                  continue;
            }
            count = sel_buffer_lth - pasted;
            count = min(count, tty->receive_room);
            tty->ldisc.receive_buf(tty, sel_buffer + pasted, NULL, count);
            pasted += count;
      }
      remove_wait_queue(&vc->paste_wait, &wait);
      __set_current_state(TASK_RUNNING);

      tty_ldisc_deref(ld);
      return 0;
}

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