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 bool vc_is_sel(struct vc_data *vc)
  87 {
  88         return vc == sel_cons;
  89 }
  90
  91 /*
  92  * User settable table: what characters are to be considered alphabetic?
  93  * 128 bits. Locked by the console lock.
  94  */
  95 static u32 inwordLut[]={
  96   0x00000000, /* control chars     */
  97   0x03FFE000, /* digits and "-./"  */
  98   0x87FFFFFE, /* uppercase and '_' */
  99   0x07FFFFFE, /* lowercase         */
 100 };
 101
 102 static inline int inword(const u16 c) {
 103         return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
 104 }
 105
 106 /**
 107  *      set loadlut             -       load the LUT table
 108  *      @p: user table
 109  *
 110  *      Load the LUT table from user space. The caller must hold the console
 111  *      lock. Make a temporary copy so a partial update doesn't make a mess.
 112  */
 113 int sel_loadlut(char __user *p)
 114 {
 115         u32 tmplut[ARRAY_SIZE(inwordLut)];
 116         if (copy_from_user(tmplut, (u32 __user *)(p+4), sizeof(inwordLut)))
 117                 return -EFAULT;
 118         memcpy(inwordLut, tmplut, sizeof(inwordLut));
 119         return 0;
 120 }
 121
 122 /* does screen address p correspond to character at LH/RH edge of screen? */
 123 static inline int atedge(const int p, int size_row)
 124 {
 125         return (!(p % size_row) || !((p + 2) % size_row));
 126 }
 127
 128 /* constrain v such that v <= u */
 129 static inline unsigned short limit(const unsigned short v, const unsigned short u)
 130 {
 131         return (v > u) ? u : v;
 132 }
 133
 134 /* stores the char in UTF8 and returns the number of bytes used (1-3) */
 135 static int store_utf8(u16 c, char *p)
 136 {
 137         if (c < 0x80) {
 138                 /*  0******* */
 139                 p[0] = c;
 140                 return 1;
 141         } else if (c < 0x800) {
 142                 /* 110***** 10****** */
 143                 p[0] = 0xc0 | (c >> 6);
 144                 p[1] = 0x80 | (c & 0x3f);
 145                 return 2;
 146         } else {
 147                 /* 1110**** 10****** 10****** */
 148                 p[0] = 0xe0 | (c >> 12);
 149                 p[1] = 0x80 | ((c >> 6) & 0x3f);
 150                 p[2] = 0x80 | (c & 0x3f);
 151                 return 3;
 152         }
 153 }
 154
 155 /**
 156  *      set_selection           -       set the current selection.
 157  *      @sel: user selection info
 158  *      @tty: the console tty
 159  *
 160  *      Invoked by the ioctl handle for the vt layer.
 161  *
 162  *      The entire selection process is managed under the console_lock. It's
 163  *       a lot under the lock but its hardly a performance path
 164  */
 165 static int __set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
 166 {
 167         struct vc_data *vc = vc_cons[fg_console].d;
 168         int sel_mode, new_sel_start, new_sel_end, spc;
 169         char *bp, *obp;
 170         int i, ps, pe, multiplier;
 171         u16 c;
 172         int mode, ret = 0;
 173
 174         poke_blanked_console();
 175
 176         { unsigned short xs, ys, xe, ye;
 177
 178           if (!access_ok(VERIFY_READ, sel, sizeof(*sel)))
 179                 return -EFAULT;
 180           __get_user(xs, &sel->xs);
 181           __get_user(ys, &sel->ys);
 182           __get_user(xe, &sel->xe);
 183           __get_user(ye, &sel->ye);
 184           __get_user(sel_mode, &sel->sel_mode);
 185           xs--; ys--; xe--; ye--;
 186           xs = limit(xs, vc->vc_cols - 1);
 187           ys = limit(ys, vc->vc_rows - 1);
 188           xe = limit(xe, vc->vc_cols - 1);
 189           ye = limit(ye, vc->vc_rows - 1);
 190           ps = ys * vc->vc_size_row + (xs << 1);
 191           pe = ye * vc->vc_size_row + (xe << 1);
 192
 193           if (sel_mode == TIOCL_SELCLEAR) {
 194               /* useful for screendump without selection highlights */
 195               clear_selection();
 196               return 0;
 197           }
 198
 199           if (mouse_reporting() && (sel_mode & TIOCL_SELMOUSEREPORT)) {
 200               mouse_report(tty, sel_mode & TIOCL_SELBUTTONMASK, xs, ys);
 201               return 0;
 202           }
 203         }
 204
 205         if (ps > pe)    /* make sel_start <= sel_end */
 206         {
 207                 int tmp = ps;
 208                 ps = pe;
 209                 pe = tmp;
 210         }
 211
 212         if (sel_cons != vc_cons[fg_console].d) {
 213                 clear_selection();
 214                 sel_cons = vc_cons[fg_console].d;
 215         }
 216         mode = vt_do_kdgkbmode(fg_console);
 217         if (mode == K_UNICODE)
 218                 use_unicode = 1;
 219         else
 220                 use_unicode = 0;
 221
 222         switch (sel_mode)
 223         {
 224                 case TIOCL_SELCHAR:     /* character-by-character selection */
 225                         new_sel_start = ps;
 226                         new_sel_end = pe;
 227                         break;
 228                 case TIOCL_SELWORD:     /* word-by-word selection */
 229                         spc = isspace(sel_pos(ps));
 230                         for (new_sel_start = ps; ; ps -= 2)
 231                         {
 232                                 if ((spc && !isspace(sel_pos(ps))) ||
 233                                     (!spc && !inword(sel_pos(ps))))
 234                                         break;
 235                                 new_sel_start = ps;
 236                                 if (!(ps % vc->vc_size_row))
 237                                         break;
 238                         }
 239                         spc = isspace(sel_pos(pe));
 240                         for (new_sel_end = pe; ; pe += 2)
 241                         {
 242                                 if ((spc && !isspace(sel_pos(pe))) ||
 243                                     (!spc && !inword(sel_pos(pe))))
 244                                         break;
 245                                 new_sel_end = pe;
 246                                 if (!((pe + 2) % vc->vc_size_row))
 247                                         break;
 248                         }
 249                         break;
 250                 case TIOCL_SELLINE:     /* line-by-line selection */
 251                         new_sel_start = ps - ps % vc->vc_size_row;
 252                         new_sel_end = pe + vc->vc_size_row
 253                                     - pe % vc->vc_size_row - 2;
 254                         break;
 255                 case TIOCL_SELPOINTER:
 256                         highlight_pointer(pe);
 257                         return 0;
 258                 default:
 259                         return -EINVAL;
 260         }
 261
 262         /* remove the pointer */
 263         highlight_pointer(-1);
 264
 265         /* select to end of line if on trailing space */
 266         if (new_sel_end > new_sel_start &&
 267                 !atedge(new_sel_end, vc->vc_size_row) &&
 268                 isspace(sel_pos(new_sel_end))) {
 269                 for (pe = new_sel_end + 2; ; pe += 2)
 270                         if (!isspace(sel_pos(pe)) ||
 271                             atedge(pe, vc->vc_size_row))
 272                                 break;
 273                 if (isspace(sel_pos(pe)))
 274                         new_sel_end = pe;
 275         }
 276         if (sel_start == -1)    /* no current selection */
 277                 highlight(new_sel_start, new_sel_end);
 278         else if (new_sel_start == sel_start)
 279         {
 280                 if (new_sel_end == sel_end)     /* no action required */
 281                         return 0;
 282                 else if (new_sel_end > sel_end) /* extend to right */
 283                         highlight(sel_end + 2, new_sel_end);
 284                 else                            /* contract from right */
 285                         highlight(new_sel_end + 2, sel_end);
 286         }
 287         else if (new_sel_end == sel_end)
 288         {
 289                 if (new_sel_start < sel_start)  /* extend to left */
 290                         highlight(new_sel_start, sel_start - 2);
 291                 else                            /* contract from left */
 292                         highlight(sel_start, new_sel_start - 2);
 293         }
 294         else    /* some other case; start selection from scratch */
 295         {
 296                 clear_selection();
 297                 highlight(new_sel_start, new_sel_end);
 298         }
 299         sel_start = new_sel_start;
 300         sel_end = new_sel_end;
 301
 302         /* Allocate a new buffer before freeing the old one ... */
 303         multiplier = use_unicode ? 3 : 1;  /* chars can take up to 3 bytes */
 304         bp = kmalloc(((sel_end-sel_start)/2+1)*multiplier, GFP_KERNEL);
 305         if (!bp) {
 306                 printk(KERN_WARNING "selection: kmalloc() failed\n");
 307                 clear_selection();
 308                 return -ENOMEM;
 309         }
 310         kfree(sel_buffer);
 311         sel_buffer = bp;
 312
 313         obp = bp;
 314         for (i = sel_start; i <= sel_end; i += 2) {
 315                 c = sel_pos(i);
 316                 if (use_unicode)
 317                         bp += store_utf8(c, bp);
 318                 else
 319                         *bp++ = c;
 320                 if (!isspace(c))
 321                         obp = bp;
 322                 if (! ((i + 2) % vc->vc_size_row)) {
 323                         /* strip trailing blanks from line and add newline,
 324                            unless non-space at end of line. */
 325                         if (obp != bp) {
 326                                 bp = obp;
 327                                 *bp++ = '\r';
 328                         }
 329                         obp = bp;
 330                 }
 331         }
 332         sel_buffer_lth = bp - sel_buffer;
 333
 334         return ret;
 335 }
 336
 337 int set_selection(const struct tiocl_selection __user *v, struct tty_struct *tty)
 338 {
 339         int ret;
 340
 341         mutex_lock(&sel_lock);
 342         console_lock();
 343         ret = __set_selection(v, tty);
 344         console_unlock();
 345         mutex_unlock(&sel_lock);
 346
 347         return ret;
 348 }
 349
 350 /* Insert the contents of the selection buffer into the
 351  * queue of the tty associated with the current console.
 352  * Invoked by ioctl().
 353  *
 354  * Locking: called without locks. Calls the ldisc wrongly with
 355  * unsafe methods,
 356  */
 357 int paste_selection(struct tty_struct *tty)
 358 {
 359         struct vc_data *vc = tty->driver_data;
 360         int     pasted = 0;
 361         unsigned int count;
 362         struct  tty_ldisc *ld;
 363         DECLARE_WAITQUEUE(wait, current);
 364         int ret = 0;
 365
 366         console_lock();
 367         poke_blanked_console();
 368         console_unlock();
 369
 370         ld = tty_ldisc_ref_wait(tty);
 371         if (!ld)
 372                 return -EIO;    /* ldisc was hung up */
 373         tty_buffer_lock_exclusive(&vc->port);
 374
 375         add_wait_queue(&vc->paste_wait, &wait);
 376         mutex_lock(&sel_lock);
 377         while (sel_buffer && sel_buffer_lth > pasted) {
 378                 set_current_state(TASK_INTERRUPTIBLE);
 379                 if (signal_pending(current)) {
 380                         ret = -EINTR;
 381                         break;
 382                 }
 383                 if (tty_throttled(tty)) {
 384                         mutex_unlock(&sel_lock);
 385                         schedule();
 386                         mutex_lock(&sel_lock);
 387                         continue;
 388                 }
 389                 __set_current_state(TASK_RUNNING);
 390                 count = sel_buffer_lth - pasted;
 391                 count = tty_ldisc_receive_buf(ld, sel_buffer + pasted, NULL,
 392                                               count);
 393                 pasted += count;
 394         }
 395         mutex_unlock(&sel_lock);
 396         remove_wait_queue(&vc->paste_wait, &wait);
 397         __set_current_state(TASK_RUNNING);
 398
 399         tty_buffer_unlock_exclusive(&vc->port);
 400         tty_ldisc_deref(ld);
 401         return ret;
 402 }