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