miscutils/conspy.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * A text-mode VNC like program for Linux virtual terminals.
   4  *
   5  * pascal.bellard@ads-lu.com
   6  *
   7  * Based on Russell Stuart's conspy.c
   8  *   http://ace-host.stuart.id.au/russell/files/conspy.c
   9  *
  10  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  11  */
  12
  13 //applet:IF_CONSPY(APPLET(conspy, BB_DIR_BIN, BB_SUID_DROP))
  14
  15 //kbuild:lib-$(CONFIG_CONSPY) += conspy.o
  16
  17 //config:config CONSPY
  18 //config:       bool "conspy"
  19 //config:       default y
  20 //config:       select PLATFORM_LINUX
  21 //config:       help
  22 //config:         A text-mode VNC like program for Linux virtual terminals.
  23 //config:         example:  conspy NUM      shared access to console num
  24 //config:         or        conspy -nd NUM  screenshot of console num
  25 //config:         or        conspy -cs NUM  poor man's GNU screen like
  26
  27 //usage:#define conspy_trivial_usage
  28 //usage:        "[-vcsndfFQ] [-x COL] [-y LINE] [CONSOLE_NO]"
  29 //usage:#define conspy_full_usage "\n\n"
  30 //usage:     "A text-mode VNC like program for Linux virtual consoles."
  31 //usage:     "\nTo exit, quickly press ESC 3 times."
  32 //usage:     "\n"
  33 //usage:     "\n        -v      Don't send keystrokes to the console"
  34 //usage:     "\n        -c      Create missing /dev/{tty,vcsa}N"
  35 //usage:     "\n        -s      Open a SHELL session"
  36 //usage:     "\n        -n      Black & white"
  37 //usage:     "\n        -d      Dump console to stdout"
  38 //usage:     "\n        -f      Follow cursor"
  39 //usage:     "\n        -F      Assume console is on a framebuffer device"
  40 //usage:     "\n        -Q      Disable exit on ESC-ESC-ESC"
  41 //usage:     "\n        -x COL  Starting column"
  42 //usage:     "\n        -y LINE Starting line"
  43
  44 #include "libbb.h"
  45 #include "common_bufsiz.h"
  46 #include <sys/kd.h>
  47
  48 #define ESC "\033"
  49 #define CURSOR_ON       -1
  50 #define CURSOR_OFF      1
  51
  52 #define DEV_TTY         "/dev/tty"
  53 #define DEV_VCSA        "/dev/vcsa"
  54
  55 struct screen_info {
  56         unsigned char lines, cols, cursor_x, cursor_y;
  57 };
  58
  59 #define CHAR(x) (*(uint8_t*)(x))
  60 #define ATTR(x) (((uint8_t*)(x))[1])
  61 #define NEXT(x) ((x) += 2)
  62 #define DATA(x) (*(uint16_t*)(x))
  63
  64 struct globals {
  65         char* data;
  66         int size;
  67         int x, y;
  68         int kbd_fd;
  69         int ioerror_count;
  70         int key_count;
  71         int escape_count;
  72         int nokeys;
  73         int current;
  74         int first_line_offset;
  75         int last_attr;
  76         // cached local tty parameters
  77         unsigned width;
  78         unsigned height;
  79         unsigned col;
  80         unsigned line;
  81         smallint curoff; // unknown:0 cursor on:-1 cursor off:1
  82         char attrbuf[sizeof("0;1;5;30;40m")];
  83         // remote console
  84         struct screen_info remote;
  85         // saved local tty terminfo
  86         struct termios term_orig;
  87         char vcsa_name[sizeof(DEV_VCSA "NN")];
  88 };
  89
  90 #define G (*ptr_to_globals)
  91 #define INIT_G() do { \
  92         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
  93         G.width = G.height = UINT_MAX; \
  94         G.last_attr--; \
  95 } while (0)
  96
  97 enum {
  98         FLAG_v,  // view only
  99         FLAG_c,  // create device if need
 100         FLAG_Q,  // never exit
 101         FLAG_s,  // session
 102         FLAG_n,  // no colors
 103         FLAG_d,  // dump screen
 104         FLAG_f,  // follow cursor
 105         FLAG_F,  // framebuffer
 106 };
 107 #define FLAG(x) (1 << FLAG_##x)
 108 #define BW (option_mask32 & FLAG(n))
 109
 110 static void putcsi(const char *s)
 111 {
 112         fputs(ESC"[", stdout);
 113         fputs(s, stdout);
 114 }
 115
 116 static void clrscr(void)
 117 {
 118         // Home, clear till end of screen
 119         putcsi("1;1H" ESC"[J");
 120         G.col = G.line = 0;
 121 }
 122
 123 static void set_cursor(int state)
 124 {
 125         if (G.curoff != state) {
 126                 G.curoff = state;
 127                 putcsi("?25");
 128                 bb_putchar("h?l"[1 + state]);
 129         }
 130 }
 131
 132 static void gotoxy(int col, int line)
 133 {
 134         if (G.col != col || G.line != line) {
 135                 G.col = col;
 136                 G.line = line;
 137                 printf(ESC"[%u;%uH", line + 1, col + 1);
 138         }
 139 }
 140
 141 static void cleanup(int code) NORETURN;
 142 static void cleanup(int code)
 143 {
 144         set_cursor(CURSOR_ON);
 145         tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
 146         if (ENABLE_FEATURE_CLEAN_UP) {
 147                 close(G.kbd_fd);
 148         }
 149         // Reset attributes
 150         if (!BW)
 151                 putcsi("0m");
 152         bb_putchar('\n');
 153         if (code > EXIT_FAILURE)
 154                 kill_myself_with_sig(code);
 155         exit(code);
 156 }
 157
 158 static void screen_read_close(void)
 159 {
 160         unsigned i, j;
 161         int vcsa_fd;
 162         char *data;
 163
 164         // Close & re-open vcsa in case they have swapped virtual consoles
 165         vcsa_fd = xopen(G.vcsa_name, O_RDONLY);
 166         xread(vcsa_fd, &G.remote, 4);
 167         i = G.remote.cols * 2;
 168         G.first_line_offset = G.y * i;
 169         i *= G.remote.lines;
 170         if (G.data == NULL) {
 171                 G.size = i;
 172                 G.data = xzalloc(2 * i);
 173         }
 174         if (G.size != i) {
 175                 cleanup(EXIT_FAILURE);
 176         }
 177         data = G.data + G.current;
 178         xread(vcsa_fd, data, G.size);
 179         close(vcsa_fd);
 180         for (i = 0; i < G.remote.lines; i++) {
 181                 for (j = 0; j < G.remote.cols; j++, NEXT(data)) {
 182                         unsigned x = j - G.x; // if will catch j < G.x too
 183                         unsigned y = i - G.y; // if will catch i < G.y too
 184
 185                         if (y >= G.height || x >= G.width)
 186                                 DATA(data) = 0;
 187                         else {
 188                                 uint8_t ch = CHAR(data);
 189                                 if (ch < ' ')
 190                                         CHAR(data) = ch | 0x40;
 191                                 else if (ch > 0x7e)
 192                                         CHAR(data) = '?';
 193                         }
 194                 }
 195         }
 196 }
 197
 198 static void screen_char(char *data)
 199 {
 200         if (!BW) {
 201                 uint8_t attr_diff;
 202                 uint8_t attr = ATTR(data);
 203
 204                 if (option_mask32 & FLAG(F)) {
 205                         attr >>= 1;
 206                 }
 207                 attr_diff = G.last_attr ^ attr;
 208                 if (attr_diff) {
 209 // Attribute layout for VGA compatible text videobuffer:
 210 // blinking text
 211 // |red bkgd
 212 // ||green bkgd
 213 // |||blue bkgd
 214 // vvvv
 215 // 00000000 <- lsb bit on the right
 216 //     bold text / text 8th bit
 217 //      red text
 218 //       green text
 219 //        blue text
 220 // TODO: apparently framebuffer-based console uses different layout
 221 // (bug? attempt to get 8th text bit in better position?)
 222 // red bkgd
 223 // |green bkgd
 224 // ||blue bkgd
 225 // vvv
 226 // 00000000 <- lsb bit on the right
 227 //    bold text
 228 //     red text
 229 //      green text
 230 //       blue text
 231 //        text 8th bit
 232                         // converting RGB color bit triad to BGR:
 233                         static const char color[8] = "04261537";
 234                         const uint8_t fg_mask = 0x07, bold_mask  = 0x08;
 235                         const uint8_t bg_mask = 0x70, blink_mask = 0x80;
 236                         char *ptr;
 237
 238                         ptr = G.attrbuf;
 239
 240                         // (G.last_attr & ~attr) has 1 only where
 241                         // G.last_attr has 1 but attr has 0.
 242                         // Here we check whether we have transition
 243                         // bold->non-bold or blink->non-blink:
 244                         if (G.last_attr < 0  // initial value
 245                          || ((G.last_attr & ~attr) & (bold_mask | blink_mask)) != 0
 246                         ) {
 247                                 *ptr++ = '0'; // "reset all attrs"
 248                                 *ptr++ = ';';
 249                                 // must set fg & bg, maybe need to set bold or blink:
 250                                 attr_diff = attr | ~(bold_mask | blink_mask);
 251                         }
 252                         G.last_attr = attr;
 253                         if (attr_diff & bold_mask) {
 254                                 *ptr++ = '1';
 255                                 *ptr++ = ';';
 256                         }
 257                         if (attr_diff & blink_mask) {
 258                                 *ptr++ = '5';
 259                                 *ptr++ = ';';
 260                         }
 261                         if (attr_diff & fg_mask) {
 262                                 *ptr++ = '3';
 263                                 *ptr++ = color[attr & fg_mask];
 264                                 *ptr++ = ';';
 265                         }
 266                         if (attr_diff & bg_mask) {
 267                                 *ptr++ = '4';
 268                                 *ptr++ = color[(attr & bg_mask) >> 4];
 269                                 ptr++; // last attribute
 270                         }
 271                         if (ptr != G.attrbuf) {
 272                                 ptr[-1] = 'm';
 273                                 *ptr = '\0';
 274                                 putcsi(G.attrbuf);
 275                         }
 276                 }
 277         }
 278         putchar(CHAR(data));
 279         G.col++;
 280 }
 281
 282 static void screen_dump(void)
 283 {
 284         int linefeed_cnt;
 285         int line, col;
 286         int linecnt = G.remote.lines - G.y;
 287         char *data = G.data + G.current + G.first_line_offset;
 288
 289         linefeed_cnt = 0;
 290         for (line = 0; line < linecnt && line < G.height; line++) {
 291                 int space_cnt = 0;
 292                 for (col = 0; col < G.remote.cols; col++, NEXT(data)) {
 293                         unsigned tty_col = col - G.x; // if will catch col < G.x too
 294
 295                         if (tty_col >= G.width)
 296                                 continue;
 297                         space_cnt++;
 298                         if (BW && CHAR(data) == ' ')
 299                                 continue;
 300                         while (linefeed_cnt != 0) {
 301                                 //bb_putchar('\r'); - tty driver does it for us
 302                                 bb_putchar('\n');
 303                                 linefeed_cnt--;
 304                         }
 305                         while (--space_cnt)
 306                                 bb_putchar(' ');
 307                         screen_char(data);
 308                 }
 309                 linefeed_cnt++;
 310         }
 311 }
 312
 313 static void curmove(void)
 314 {
 315         unsigned cx = G.remote.cursor_x - G.x;
 316         unsigned cy = G.remote.cursor_y - G.y;
 317         int cursor = CURSOR_OFF;
 318
 319         if (cx < G.width && cy < G.height) {
 320                 gotoxy(cx, cy);
 321                 cursor = CURSOR_ON;
 322         }
 323         set_cursor(cursor);
 324 }
 325
 326 static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
 327 {
 328         int fd = open(name, O_RDONLY);
 329         if (fd != -1)
 330                 close(fd);
 331         else if (errno == ENOENT)
 332                 mknod(name, S_IFCHR | 0660, dev);
 333 }
 334
 335 static NOINLINE void start_shell_in_child(const char* tty_name)
 336 {
 337         int pid = xvfork();
 338         if (pid == 0) {
 339                 struct termios termchild;
 340                 const char *shell = get_shell_name();
 341
 342                 signal(SIGHUP, SIG_IGN);
 343                 // set tty as a controlling tty
 344                 setsid();
 345                 // make tty to be input, output, error
 346                 close(0);
 347                 xopen(tty_name, O_RDWR); // uses fd 0
 348                 xdup2(0, 1);
 349                 xdup2(0, 2);
 350                 ioctl(0, TIOCSCTTY, 1);
 351                 tcsetpgrp(0, getpid());
 352                 tcgetattr(0, &termchild);
 353                 termchild.c_lflag |= ECHO;
 354                 termchild.c_oflag |= ONLCR | XTABS;
 355                 termchild.c_iflag |= ICRNL;
 356                 termchild.c_iflag &= ~IXOFF;
 357                 tcsetattr_stdin_TCSANOW(&termchild);
 358                 execl(shell, shell, "-i", (char *) NULL);
 359                 bb_simple_perror_msg_and_die(shell);
 360         }
 361 }
 362
 363 int conspy_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 364 int conspy_main(int argc UNUSED_PARAM, char **argv)
 365 {
 366         char tty_name[sizeof(DEV_TTY "NN")];
 367         struct termios termbuf;
 368         unsigned opts;
 369         unsigned ttynum;
 370         int poll_timeout_ms;
 371 #if ENABLE_LONG_OPTS
 372         static const char getopt_longopts[] ALIGN1 =
 373                 "viewonly\0"     No_argument "v"
 374                 "createdevice\0" No_argument "c"
 375                 "neverquit\0"    No_argument "Q"
 376                 "session\0"      No_argument "s"
 377                 "nocolors\0"     No_argument "n"
 378                 "dump\0"         No_argument "d"
 379                 "follow\0"       No_argument "f"
 380                 "framebuffer\0"  No_argument "F"
 381                 ;
 382
 383         applet_long_options = getopt_longopts;
 384 #endif
 385 #define keybuf bb_common_bufsiz1
 386         setup_common_bufsiz();
 387
 388         INIT_G();
 389         strcpy(G.vcsa_name, DEV_VCSA);
 390
 391         opt_complementary = "x+:y+"; // numeric params
 392         opts = getopt32(argv, "vcQsndfFx:y:", &G.x, &G.y);
 393         argv += optind;
 394         ttynum = 0;
 395         if (argv[0]) {
 396                 ttynum = xatou_range(argv[0], 0, 63);
 397                 sprintf(G.vcsa_name + sizeof(DEV_VCSA)-1, "%u", ttynum);
 398         }
 399         sprintf(tty_name, "%s%u", DEV_TTY, ttynum);
 400         if (opts & FLAG(c)) {
 401                 if ((opts & (FLAG(s)|FLAG(v))) != FLAG(v))
 402                         create_cdev_if_doesnt_exist(tty_name, makedev(4, ttynum));
 403                 create_cdev_if_doesnt_exist(G.vcsa_name, makedev(7, 128 + ttynum));
 404         }
 405         if ((opts & FLAG(s)) && ttynum) {
 406                 start_shell_in_child(tty_name);
 407         }
 408
 409         screen_read_close();
 410         if (opts & FLAG(d)) {
 411                 screen_dump();
 412                 bb_putchar('\n');
 413                 return 0;
 414         }
 415
 416         bb_signals(BB_FATAL_SIGS, cleanup);
 417
 418         // All characters must be passed through to us unaltered
 419         G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
 420         tcgetattr(G.kbd_fd, &G.term_orig);
 421         termbuf = G.term_orig;
 422         termbuf.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
 423         //termbuf.c_oflag &= ~(OPOST); - no, we still want \n -> \r\n
 424         termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
 425         termbuf.c_cc[VMIN] = 1;
 426         termbuf.c_cc[VTIME] = 0;
 427         tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
 428
 429         poll_timeout_ms = 250;
 430         while (1) {
 431                 struct pollfd pfd;
 432                 int bytes_read;
 433                 int i, j;
 434                 char *data, *old;
 435
 436                 // in the first loop G.width = G.height = 0: refresh
 437                 i = G.width;
 438                 j = G.height;
 439                 get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
 440                 if (option_mask32 & FLAG(f)) {
 441                         int nx = G.remote.cursor_x - G.width + 1;
 442                         int ny = G.remote.cursor_y - G.height + 1;
 443
 444                         if (G.remote.cursor_x < G.x) {
 445                                 G.x = G.remote.cursor_x;
 446                                 i = 0; // force refresh
 447                         }
 448                         if (nx > G.x) {
 449                                 G.x = nx;
 450                                 i = 0; // force refresh
 451                         }
 452                         if (G.remote.cursor_y < G.y) {
 453                                 G.y = G.remote.cursor_y;
 454                                 i = 0; // force refresh
 455                         }
 456                         if (ny > G.y) {
 457                                 G.y = ny;
 458                                 i = 0; // force refresh
 459                         }
 460                 }
 461
 462                 // Scan console data and redraw our tty where needed
 463                 old = G.data + G.current;
 464                 G.current = G.size - G.current;
 465                 data = G.data + G.current;
 466                 screen_read_close();
 467                 if (i != G.width || j != G.height) {
 468                         clrscr();
 469                         screen_dump();
 470                 } else {
 471                         // For each remote line
 472                         old += G.first_line_offset;
 473                         data += G.first_line_offset;
 474                         for (i = G.y; i < G.remote.lines; i++) {
 475                                 char *first = NULL; // first char which needs updating
 476                                 char *last = last;  // last char which needs updating
 477                                 unsigned iy = i - G.y;
 478
 479                                 if (iy >= G.height)
 480                                         break;
 481                                 for (j = 0; j < G.remote.cols; j++, NEXT(old), NEXT(data)) {
 482                                         unsigned jx = j - G.x; // if will catch j >= G.x too
 483
 484                                         if (jx < G.width && DATA(data) != DATA(old)) {
 485                                                 last = data;
 486                                                 if (!first) {
 487                                                         first = data;
 488                                                         gotoxy(jx, iy);
 489                                                 }
 490                                         }
 491                                 }
 492                                 if (first) {
 493                                         // Rewrite updated data on the local screen
 494                                         for (; first <= last; NEXT(first))
 495                                                 screen_char(first);
 496                                 }
 497                         }
 498                 }
 499                 curmove();
 500
 501                 // Wait for local user keypresses
 502                 fflush_all();
 503                 pfd.fd = G.kbd_fd;
 504                 pfd.events = POLLIN;
 505                 bytes_read = 0;
 506                 switch (poll(&pfd, 1, poll_timeout_ms)) {
 507                         char *k;
 508                 case -1:
 509                         if (errno != EINTR)
 510                                 goto abort;
 511                         break;
 512                 case 0:
 513                         if (++G.nokeys >= 4)
 514                                 G.nokeys = G.escape_count = 0;
 515                         break;
 516                 default:
 517                         // Read the keys pressed
 518                         k = keybuf + G.key_count;
 519                         bytes_read = read(G.kbd_fd, k, COMMON_BUFSIZE - G.key_count);
 520                         if (bytes_read < 0)
 521                                 goto abort;
 522
 523                         // Do exit processing
 524                         if (!(option_mask32 & FLAG(Q))) {
 525                                 for (i = 0; i < bytes_read; i++) {
 526                                         if (k[i] != '\033')
 527                                                 G.escape_count = -1;
 528                                         if (++G.escape_count >= 3)
 529                                                 cleanup(EXIT_SUCCESS);
 530                                 }
 531                         }
 532                 }
 533                 poll_timeout_ms = 250;
 534                 if (option_mask32 & FLAG(v)) continue;
 535
 536                 // Insert all keys pressed into the virtual console's input
 537                 // buffer.  Don't do this if the virtual console is in scan
 538                 // code mode - giving ASCII characters to a program expecting
 539                 // scan codes will confuse it.
 540                 G.key_count += bytes_read;
 541                 if (G.escape_count == 0) {
 542                         int handle, result;
 543                         long kbd_mode;
 544
 545                         handle = xopen(tty_name, O_WRONLY);
 546                         result = ioctl(handle, KDGKBMODE, &kbd_mode);
 547                         if (result >= 0) {
 548                                 char *p = keybuf;
 549
 550                                 G.ioerror_count = 0;
 551                                 if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE) {
 552                                         G.key_count = 0; // scan code mode
 553                                 }
 554                                 for (; G.key_count != 0; p++, G.key_count--) {
 555                                         result = ioctl(handle, TIOCSTI, p);
 556                                         if (result < 0) {
 557                                                 memmove(keybuf, p, G.key_count);
 558                                                 break;
 559                                         }
 560                                         // If there is an application on console which reacts
 561                                         // to keypresses, we need to make our first sleep
 562                                         // shorter to quickly redraw whatever it printed there.
 563                                         poll_timeout_ms = 20;
 564                                 }
 565                         }
 566                         // We sometimes get spurious IO errors on the TTY
 567                         // as programs close and re-open it
 568                         else if (errno != EIO || ++G.ioerror_count > 4) {
 569                                 if (ENABLE_FEATURE_CLEAN_UP)
 570                                         close(handle);
 571                                 goto abort;
 572                         }
 573                         // Close & re-open tty in case they have
 574                         // swapped virtual consoles
 575                         close(handle);
 576                 }
 577         } /* while (1) */
 578   abort:
 579         cleanup(EXIT_FAILURE);
 580 }