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