drivers/tty/vt/selection.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This module exports the functions:
   4  *
   5  *     'int set_selection(struct tiocl_selection __user *, struct tty_struct *)'
   6  *     'void clear_selection(void)'
   7  *     'int paste_selection(struct tty_struct *)'
   8  *     'int sel_loadlut(char __user *)'
   9  *
  10  * Now that /dev/vcs exists, most of this can disappear again.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/tty.h>
  15 #include <linux/sched.h>
  16 #include <linux/mm.h>
  17 #include <linux/mutex.h>
  18 #include <linux/slab.h>
  19 #include <linux/types.h>
  20
  21 #include <linux/uaccess.h>
  22
  23 #include <linux/kbd_kern.h>
  24 #include <linux/vt_kern.h>
  25 #include <linux/consolemap.h>
  26 #include <linux/selection.h>
  27 #include <linux/tiocl.h>
  28 #include <linux/console.h>
  29 #include <linux/tty_flip.h>
  30
  31 #include <linux/sched/signal.h>
  32
  33 /* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
  34 #define isspace(c)      ((c) == ' ')
  35
  36 extern void poke_blanked_console(void);
  37
  38 /* FIXME: all this needs locking */
  39 /* Variables for selection control. */
  40 /* Use a dynamic buffer, instead of static (Dec 1994) */
  41 struct vc_data *sel_cons;               /* must not be deallocated */
  42 static int use_unicode;
  43 static volatile int sel_start = -1;     /* cleared by clear_selection */
  44 static int sel_end;
  45 static int sel_buffer_lth;
  46 static char *sel_buffer;
  47 static DEFINE_MUTEX(sel_lock);
  48
  49 /* clear_selection, highlight and highlight_pointer can be called
  50    from interrupt (via scrollback/front) */
  51
  52 /* set reverse video on characters s-e of console with selection. */
  53 static inline void highlight(const int s, const int e)
  54 {
  55         invert_screen(sel_cons, s, e-s+2, 1);
  56 }
  57
  58 /* use complementary color to show the pointer */
  59 static inline void highlight_pointer(const int where)
  60 {
  61         complement_pos(sel_cons, where);
  62 }
  63
  64 static u16
  65 sel_pos(int n)
  66 {
  67         return inverse_translate(sel_cons, screen_glyph(sel_cons, n),
  68                                 use_unicode);
  69 }
  70
  71 /**
  72  *      clear_selection         -       remove current selection
  73  *
  74  *      Remove the current selection highlight, if any from the console
  75  *      holding the selection. The caller must hold the console lock.
  76  */
  77 void clear_selection(void)
  78 {
  79         highlight_pointer(-1); /* hide the pointer */
  80         if (sel_start != -1) {
  81                 highlight(sel_start, sel_end);
  82                 sel_start = -1;
  83         }
  84 }
  85
  86 /*
  87  * User settable table: what characters are to be considered alphabetic?
  88  * 128 bits. Locked by the console lock.
  89  */
  90 static u32 inwordLut[]={
  91   0x00000000, /* control chars     */
  92   0x03FFE000, /* digits and "-./"  */
  93   0x87FFFFFE, /* uppercase and '_' */
  94   0x07FFFFFE, /* lowercase         */
  95 };
  96
  97 static inline int inword(const u16 c) {
  98         return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
  99 }
 100
 101 /**
 102  *      set loadlut             -       load the LUT table
 103  *      @p: user table
 104  *
 105  *      Load the LUT table from user space. The caller must hold the console
 106  *      lock. Make a temporary copy so a partial update doesn't make a mess.
 107  */
 108 int sel_loadlut(char __user *p)
 109 {
 110         u32 tmplut[ARRAY_SIZE(inwordLut)];
 111         if (copy_from_user(tmplut, (u32 __user *)(p+4), sizeof(inwordLut)))
 112                 return -EFAULT;
 113         memcpy(inwordLut, tmplut, sizeof(inwordLut));
 114         return 0;
 115 }
 116
 117 /* does screen address p correspond to character at LH/RH edge of screen? */
 118 static inline int atedge(const int p, int size_row)
 119 {
 120         return (!(p % size_row) || !((p + 2) % size_row));
 121 }
 122
 123 /* constrain v such that v <= u */
 124 static inline unsigned short limit(const unsigned short v, const unsigned short u)
 125 {
 126         return (v > u) ? u : v;
 127 }
 128
 129 /* stores the char in UTF8 and returns the number of bytes used (1-3) */
 130 static int store_utf8(u16 c, char *p)
 131 {
 132         if (c < 0x80) {
 133                 /*  0******* */
 134                 p[0] = c;
 135                 return 1;
 136         } else if (c < 0x800) {
 137                 /* 110***** 10****** */
 138                 p[0] = 0xc0 | (c >> 6);
 139                 p[1] = 0x80 | (c & 0x3f);
 140                 return 2;
 141         } else {
 142                 /* 1110**** 10****** 10****** */
 143                 p[0] = 0xe0 | (c >> 12);
 144                 p[1] = 0x80 | ((c >> 6) & 0x3f);
 145                 p[2] = 0x80 | (c & 0x3f);
 146                 return 3;
 147         }
 148 }
 149
 150 /**
 151  *      set_selection           -       set the current selection.
 152  *      @sel: user selection info
 153  *      @tty: the console tty
 154  *
 155  *      Invoked by the ioctl handle for the vt layer.
 156  *
 157  *      The entire selection process is managed under the console_lock. It's
 158  *       a lot under the lock but its hardly a performance path
 159  */
 160 static int __set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
 161 {
 162         struct vc_data *vc = vc_cons[fg_console].d;
 163         int sel_mode, new_sel_start, new_sel_end, spc;
 164         char *bp, *obp;
 165         int i, ps, pe, multiplier;
 166         u16 c;
 167         int mode, ret = 0;
 168
 169         poke_blanked_console();
 170
 171         { unsigned short xs, ys, xe, ye;
 172
 173           if (!access_ok(VERIFY_READ, sel, sizeof(*sel)))
 174                 return -EFAULT;
 175           __get_user(xs, &sel->xs);
 176           __get_user(ys, &sel->ys);
 177           __get_user(xe, &sel->xe);
 178           __get_user(ye, &sel->ye);
 179           __get_user(sel_mode, &sel->sel_mode);
 180           xs--; ys--; xe--; ye--;
 181           xs = limit(xs, vc->vc_cols - 1);
 182           ys = limit(ys, vc->vc_rows - 1);
 183           xe = limit(xe, vc->vc_cols - 1);
 184           ye = limit(ye, vc->vc_rows - 1);
 185           ps = ys * vc->vc_size_row + (xs << 1);
 186           pe = ye * vc->vc_size_row + (xe << 1);
 187
 188           if (sel_mode == TIOCL_SELCLEAR) {
 189               /* useful for screendump without selection highlights */
 190               clear_selection();
 191               return 0;
 192           }
 193
 194           if (mouse_reporting() && (sel_mode & TIOCL_SELMOUSEREPORT)) {
 195               mouse_report(tty, sel_mode & TIOCL_SELBUTTONMASK, xs, ys);
 196               return 0;
 197           }
 198         }
 199
 200         if (ps > pe)    /* make sel_start <= sel_end */
 201         {
 202                 int tmp = ps;
 203                 ps = pe;
 204                 pe = tmp;
 205         }
 206
 207         mutex_lock(&sel_lock);
 208         if (sel_cons != vc_cons[fg_console].d) {
 209                 clear_selection();
 210                 sel_cons = vc_cons[fg_console].d;
 211         }
 212         mode = vt_do_kdgkbmode(fg_console);
 213         if (mode == K_UNICODE)
 214                 use_unicode = 1;
 215         else
 216                 use_unicode = 0;
 217
 218         switch (sel_mode)
 219         {
 220                 case TIOCL_SELCHAR:     /* character-by-character selection */
 221                         new_sel_start = ps;
 222                         new_sel_end = pe;
 223                         break;
 224                 case TIOCL_SELWORD:     /* word-by-word selection */
 225                         spc = isspace(sel_pos(ps));
 226                         for (new_sel_start = ps; ; ps -= 2)
 227                         {
 228                                 if ((spc && !isspace(sel_pos(ps))) ||
 229                                     (!spc && !inword(sel_pos(ps))))
 230                                         break;
 231                                 new_sel_start = ps;
 232                                 if (!(ps % vc->vc_size_row))
 233                                         break;
 234                         }
 235                         spc = isspace(sel_pos(pe));
 236                         for (new_sel_end = pe; ; pe += 2)
 237                         {
 238                                 if ((spc && !isspace(sel_pos(pe))) ||
 239                                     (!spc && !inword(sel_pos(pe))))
 240                                         break;
 241                                 new_sel_end = pe;
 242                                 if (!((pe + 2) % vc->vc_size_row))
 243                                         break;
 244                         }
 245                         break;
 246                 case TIOCL_SELLINE:     /* line-by-line selection */
 247                         new_sel_start = ps - ps % vc->vc_size_row;
 248                         new_sel_end = pe + vc->vc_size_row
 249                                     - pe % vc->vc_size_row - 2;
 250                         break;
 251                 case TIOCL_SELPOINTER:
 252                         highlight_pointer(pe);
 253                         goto unlock;
 254                 default:
 255                         ret = -EINVAL;
 256                         goto unlock;
 257         }
 258
 259         /* remove the pointer */
 260         highlight_pointer(-1);
 261
 262         /* select to end of line if on trailing space */
 263         if (new_sel_end > new_sel_start &&
 264                 !atedge(new_sel_end, vc->vc_size_row) &&
 265                 isspace(sel_pos(new_sel_end))) {
 266                 for (pe = new_sel_end + 2; ; pe += 2)
 267                         if (!isspace(sel_pos(pe)) ||
 268                             atedge(pe, vc->vc_size_row))
 269                                 break;
 270                 if (isspace(sel_pos(pe)))
 271                         new_sel_end = pe;
 272         }
 273         if (sel_start == -1)    /* no current selection */
 274                 highlight(new_sel_start, new_sel_end);
 275         else if (new_sel_start == sel_start)
 276         {
 277                 if (new_sel_end == sel_end)     /* no action required */
 278                         goto unlock;
 279                 else if (new_sel_end > sel_end) /* extend to right */
 280                         highlight(sel_end + 2, new_sel_end);
 281                 else                            /* contract from right */
 282                         highlight(new_sel_end + 2, sel_end);
 283         }
 284         else if (new_sel_end == sel_end)
 285         {
 286                 if (new_sel_start < sel_start)  /* extend to left */
 287                         highlight(new_sel_start, sel_start - 2);
 288                 else                            /* contract from left */
 289                         highlight(sel_start, new_sel_start - 2);
 290         }
 291         else    /* some other case; start selection from scratch */
 292         {
 293                 clear_selection();
 294                 highlight(new_sel_start, new_sel_end);
 295         }
 296         sel_start = new_sel_start;
 297         sel_end = new_sel_end;
 298
 299         /* Allocate a new buffer before freeing the old one ... */
 300         multiplier = use_unicode ? 3 : 1;  /* chars can take up to 3 bytes */
 301         bp = kmalloc(((sel_end-sel_start)/2+1)*multiplier, GFP_KERNEL);
 302         if (!bp) {
 303                 printk(KERN_WARNING "selection: kmalloc() failed\n");
 304                 clear_selection();
 305                 ret = -ENOMEM;
 306                 goto unlock;
 307         }
 308         kfree(sel_buffer);
 309         sel_buffer = bp;
 310
 311         obp = bp;
 312         for (i = sel_start; i <= sel_end; i += 2) {
 313                 c = sel_pos(i);
 314                 if (use_unicode)
 315                         bp += store_utf8(c, bp);
 316                 else
 317                         *bp++ = c;
 318                 if (!isspace(c))
 319                         obp = bp;
 320                 if (! ((i + 2) % vc->vc_size_row)) {
 321                         /* strip trailing blanks from line and add newline,
 322                            unless non-space at end of line. */
 323                         if (obp != bp) {
 324                                 bp = obp;
 325                                 *bp++ = '\r';
 326                         }
 327                         obp = bp;
 328                 }
 329         }
 330         sel_buffer_lth = bp - sel_buffer;
 331 unlock:
 332         mutex_unlock(&sel_lock);
 333         return ret;
 334 }
 335
 336 int set_selection(const struct tiocl_selection __user *v, struct tty_struct *tty)
 337 {
 338         int ret;
 339
 340         console_lock();
 341         ret = __set_selection(v, tty);
 342         console_unlock();
 343
 344         return ret;
 345 }
 346
 347 /* Insert the contents of the selection buffer into the
 348  * queue of the tty associated with the current console.
 349  * Invoked by ioctl().
 350  *
 351  * Locking: called without locks. Calls the ldisc wrongly with
 352  * unsafe methods,
 353  */
 354 int paste_selection(struct tty_struct *tty)
 355 {
 356         struct vc_data *vc = tty->driver_data;
 357         int     pasted = 0;
 358         unsigned int count;
 359         struct  tty_ldisc *ld;
 360         DECLARE_WAITQUEUE(wait, current);
 361         int ret = 0;
 362
 363         console_lock();
 364         poke_blanked_console();
 365         console_unlock();
 366
 367         ld = tty_ldisc_ref_wait(tty);
 368         if (!ld)
 369                 return -EIO;    /* ldisc was hung up */
 370         tty_buffer_lock_exclusive(&vc->port);
 371
 372         add_wait_queue(&vc->paste_wait, &wait);
 373         mutex_lock(&sel_lock);
 374         while (sel_buffer && sel_buffer_lth > pasted) {
 375                 set_current_state(TASK_INTERRUPTIBLE);
 376                 if (signal_pending(current)) {
 377                         ret = -EINTR;
 378                         break;
 379                 }
 380                 if (tty_throttled(tty)) {
 381                         mutex_unlock(&sel_lock);
 382                         schedule();
 383                         mutex_lock(&sel_lock);
 384                         continue;
 385                 }
 386                 __set_current_state(TASK_RUNNING);
 387                 count = sel_buffer_lth - pasted;
 388                 count = tty_ldisc_receive_buf(ld, sel_buffer + pasted, NULL,
 389                                               count);
 390                 pasted += count;
 391         }
 392         mutex_unlock(&sel_lock);
 393         remove_wait_queue(&vc->paste_wait, &wait);
 394         __set_current_state(TASK_RUNNING);
 395
 396         tty_buffer_unlock_exclusive(&vc->port);
 397         tty_ldisc_deref(ld);
 398         return ret;
 399 }