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 tarball for details.
  11  *
  12  * example :    conspy num              shared access to console num
  13  * or           conspy -d num           screenshot of console num
  14  * or           conspy -cs num          poor man's GNU screen like
  15  */
  16
  17 //applet:IF_CONSPY(APPLET(conspy, _BB_DIR_BIN, _BB_SUID_DROP))
  18
  19 //kbuild:lib-$(CONFIG_CONSPY) += conspy.o
  20
  21 //config:config CONSPY
  22 //config:       bool "conspy"
  23 //config:       default n
  24 //config:       help
  25 //config:         A text-mode VNC like program for Linux virtual terminals.
  26 //config:         example : conspy num      shared access to console num
  27 //config:         or        conspy -d num   screenshot of console num
  28 //config:         or        conspy -cs num  poor man's GNU screen like
  29
  30 //usage:#define conspy_trivial_usage
  31 //usage:     "[-vcsndf] [-x ROW] [-y LINE] [CONSOLE_NO]"
  32 //usage:#define conspy_full_usage "\n\n"
  33 //usage:     "A text-mode VNC like program for Linux virtual consoles."
  34 //usage:     "\nTo exit, quickly press ESC 3 times."
  35 //usage:     "\n"
  36 //usage:     "\nOptions:"
  37 //usage:     "\n        -v      Don't send keystrokes to the console"
  38 //usage:     "\n        -c      Create missing devices in /dev"
  39 //usage:     "\n        -s      Open a SHELL session"
  40 //usage:     "\n        -n      Black & white"
  41 //usage:     "\n        -d      Dump console to stdout"
  42 //usage:     "\n        -f      Follow cursor"
  43 //usage:     "\n        -x ROW  Starting row"
  44 //usage:     "\n        -y LINE Starting line"
  45
  46 #include "libbb.h"
  47 #include <sys/kd.h>
  48
  49 struct screen_info {
  50         unsigned char lines, rows, cursor_x, cursor_y;
  51 };
  52
  53 #define CHAR(x) ((x)[0])
  54 #define ATTR(x) ((x)[1])
  55 #define NEXT(x) ((x)+=2)
  56 #define DATA(x) (* (short *) (x))
  57
  58 struct globals {
  59         char* data;
  60         int size;
  61         int x, y;
  62         int kbd_fd;
  63         unsigned width;
  64         unsigned height;
  65         uint8_t last_attr;
  66         int ioerror_count;
  67         int key_count;
  68         int escape_count;
  69         int nokeys;
  70         int current;
  71         int vcsa_fd;
  72         struct screen_info info;
  73         struct termios term_orig;
  74 };
  75
  76 #define G (*ptr_to_globals)
  77 #define INIT_G() do { \
  78         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
  79 } while (0)
  80
  81 enum {
  82         FLAG_v,  // view only
  83         FLAG_c,  // create device if need
  84         FLAG_s,  // session
  85         FLAG_n,  // no colors
  86         FLAG_d,  // dump screen
  87         FLAG_f,  // follow cursor
  88 };
  89 #define FLAG(x) (1 << FLAG_##x)
  90 #define BW (option_mask32 & FLAG(n))
  91
  92 static void screen_read_close(void)
  93 {
  94         unsigned i, j;
  95         char *data = G.data + G.current;
  96
  97         xread(G.vcsa_fd, data, G.size);
  98         G.last_attr = 0;
  99         for (i = 0; i < G.info.lines; i++) {
 100                 for (j = 0; j < G.info.rows; j++, NEXT(data)) {
 101                         unsigned x = j - G.x; // if will catch j < G.x too
 102                         unsigned y = i - G.y; // if will catch i < G.y too
 103
 104                         if (CHAR(data) < ' ')
 105                                 CHAR(data) = ' ';
 106                         if (y >= G.height || x >= G.width)
 107                                 DATA(data) = 0;
 108                 }
 109         }
 110         close(G.vcsa_fd);
 111 }
 112
 113 static void screen_char(char *data)
 114 {
 115         uint8_t attr = ATTR(data);
 116
 117         if (!BW && G.last_attr != attr) {
 118 // Attribute layout for VGA compatible text videobuffer:
 119 // blinking text
 120 // |red bkgd
 121 // ||green bkgd
 122 // |||blue bkgd
 123 // vvvv
 124 // 00000000 <- lsb bit on the right
 125 //     bold text / text 8th bit
 126 //      red text
 127 //       green text
 128 //        blue text
 129 // TODO: apparently framebuffer-based console uses different layout
 130 // (bug? attempt to get 8th text bit in better position?)
 131 // red bkgd
 132 // |green bkgd
 133 // ||blue bkgd
 134 // vvv
 135 // 00000000 <- lsb bit on the right
 136 //    bold text
 137 //     red text
 138 //      green text
 139 //       blue text
 140 //        text 8th bit
 141                 // converting RGB color bit triad to BGR:
 142                 static const char color[8] = "04261537";
 143
 144                 G.last_attr = attr;
 145                 printf("\033[%c;4%c;3%cm",
 146                         (attr & 8) ? '1' : '0', // bold text / reset all
 147                         color[(attr >> 4) & 7], // bkgd color
 148                         color[attr & 7] // text color
 149                 );
 150         }
 151         putchar(CHAR(data));
 152 }
 153
 154 #define clrscr()  printf("\033[1;1H" "\033[0J")
 155 #define curoff()  printf("\033[?25l")
 156
 157 static void curon(void)
 158 {
 159         printf("\033[?25h");
 160 }
 161
 162 static void gotoxy(int row, int line)
 163 {
 164         printf("\033[%u;%uH", line + 1, row + 1);
 165 }
 166
 167 static void screen_dump(void)
 168 {
 169         int linefeed_cnt;
 170         int line, row;
 171         int linecnt = G.info.lines - G.y;
 172         char *data = G.data + G.current + (2 * G.y * G.info.rows);
 173
 174         linefeed_cnt = 0;
 175         for (line = 0; line < linecnt && line < G.height; line++) {
 176                 int space_cnt = 0;
 177                 for (row = 0; row < G.info.rows; row++, NEXT(data)) {
 178                         unsigned tty_row = row - G.x; // if will catch row < G.x too
 179
 180                         if (tty_row >= G.width)
 181                                 continue;
 182                         space_cnt++;
 183                         if (BW && (CHAR(data) | ' ') == ' ')
 184                                 continue;
 185                         while (linefeed_cnt != 0) {
 186                                 bb_putchar('\r');
 187                                 bb_putchar('\n');
 188                                 linefeed_cnt--;
 189                         }
 190                         while (--space_cnt)
 191                                 bb_putchar(' ');
 192                         screen_char(data);
 193                 }
 194                 linefeed_cnt++;
 195         }
 196 }
 197
 198 static void curmove(void)
 199 {
 200         unsigned cx = G.info.cursor_x - G.x;
 201         unsigned cy = G.info.cursor_y - G.y;
 202
 203         if (cx >= G.width || cy >= G.height) {
 204                 curoff();
 205         } else {
 206                 curon();
 207                 gotoxy(cx, cy);
 208         }
 209         fflush_all();
 210 }
 211
 212 static void cleanup(int code)
 213 {
 214         curon();
 215         fflush_all();
 216         tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
 217         if (ENABLE_FEATURE_CLEAN_UP) {
 218                 free(ptr_to_globals);
 219                 close(G.kbd_fd);
 220         }
 221         // Reset attributes
 222         if (!BW)
 223                 printf("\033[0m");
 224         bb_putchar('\n');
 225         if (code > 1)
 226                 kill_myself_with_sig(code); // does not return
 227         exit(code);
 228 }
 229
 230 static void get_initial_data(const char* vcsa_name)
 231 {
 232         int size;
 233         G.vcsa_fd = xopen(vcsa_name, O_RDONLY);
 234         xread(G.vcsa_fd, &G.info, 4);
 235         G.size = size = G.info.rows * G.info.lines * 2;
 236         G.width = G.height = UINT_MAX;
 237         G.data = xzalloc(2 * size);
 238         screen_read_close();
 239 }
 240
 241 static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
 242 {
 243         int fd = open(name, O_RDONLY);
 244         if (fd != -1)
 245                 close(fd);
 246         else if (errno == ENOENT)
 247                 mknod(name, S_IFCHR | 0660, dev);
 248 }
 249
 250 static NOINLINE void start_shell_in_child(const char* tty_name)
 251 {
 252         int pid = vfork();
 253         if (pid < 0) {
 254                 bb_perror_msg_and_die("vfork");
 255         }
 256         if (pid == 0) {
 257                 struct termios termchild;
 258                 char *shell = getenv("SHELL");
 259
 260                 if (!shell)
 261                         shell = (char *) DEFAULT_SHELL;
 262                 signal(SIGHUP, SIG_IGN);
 263                 // set tty as a controlling tty
 264                 setsid();
 265                 // make tty to be input, output, error
 266                 close(0);
 267                 xopen(tty_name, O_RDWR); // uses fd 0
 268                 xdup2(0, 1);
 269                 xdup2(0, 2);
 270                 ioctl(0, TIOCSCTTY, 1);
 271                 tcsetpgrp(0, getpid());
 272                 tcgetattr(0, &termchild);
 273                 termchild.c_lflag |= ECHO;
 274                 termchild.c_oflag |= ONLCR | XTABS;
 275                 termchild.c_iflag |= ICRNL;
 276                 termchild.c_iflag &= ~IXOFF;
 277                 tcsetattr_stdin_TCSANOW(&termchild);
 278                 execl(shell, shell, "-i", (char *) NULL);
 279                 bb_simple_perror_msg_and_die(shell);
 280         }
 281 }
 282
 283 int conspy_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
 284 int conspy_main(int argc UNUSED_PARAM, char **argv)
 285 {
 286         char vcsa_name[sizeof("/dev/vcsa") + 2];
 287         char tty_name[sizeof("/dev/tty") + 2];
 288 #define keybuf bb_common_bufsiz1
 289         struct termios termbuf;
 290         unsigned opts;
 291         unsigned ttynum;
 292         int poll_timeout_ms;
 293 #if ENABLE_LONG_OPTS
 294         static const char getopt_longopts[] ALIGN1 =
 295                 "viewonly\0"     No_argument "v"
 296                 "createdevice\0" No_argument "c"
 297                 "session\0"      No_argument "s"
 298                 "nocolors\0"     No_argument "n"
 299                 "dump\0"         No_argument "d"
 300                 "follow\0"       No_argument "f"
 301                 ;
 302
 303         applet_long_options = getopt_longopts;
 304 #endif
 305         INIT_G();
 306
 307         opt_complementary = "x+:y+"; // numeric params
 308         opts = getopt32(argv, "vcsndfx:y:", &G.x, &G.y);
 309         argv += optind;
 310         ttynum = 0;
 311         if (argv[0]) {
 312                 ttynum = xatou_range(argv[0], 0, 63);
 313         }
 314         sprintf(vcsa_name, "/dev/vcsa%u", ttynum);
 315         sprintf(tty_name, "%s%u", "/dev/tty", ttynum);
 316         if (opts & FLAG(c)) {
 317                 if ((opts & (FLAG(s)|FLAG(v))) != FLAG(v))
 318                         create_cdev_if_doesnt_exist(tty_name, makedev(4, ttynum));
 319                 create_cdev_if_doesnt_exist(vcsa_name, makedev(7, 128 + ttynum));
 320         }
 321         if ((opts & FLAG(s)) && ttynum) {
 322                 start_shell_in_child(tty_name);
 323         }
 324
 325         get_initial_data(vcsa_name);
 326         G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
 327         if (opts & FLAG(d)) {
 328                 screen_dump();
 329                 bb_putchar('\n');
 330                 if (ENABLE_FEATURE_CLEAN_UP) {
 331                         free(ptr_to_globals);
 332                         close(G.kbd_fd);
 333                 }
 334                 return 0;
 335         }
 336
 337         bb_signals(BB_FATAL_SIGS, cleanup);
 338         // All characters must be passed through to us unaltered
 339         tcgetattr(G.kbd_fd, &G.term_orig);
 340         termbuf = G.term_orig;
 341         termbuf.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
 342         termbuf.c_oflag &= ~(OPOST);
 343         termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
 344         termbuf.c_cc[VMIN] = 1;
 345         termbuf.c_cc[VTIME] = 0;
 346         tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
 347         poll_timeout_ms = 250;
 348         while (1) {
 349                 struct pollfd pfd;
 350                 int bytes_read;
 351                 int i, j;
 352                 char *data, *old;
 353
 354                 old = G.data + G.current;
 355                 G.current = G.size - G.current;
 356                 data = G.data + G.current;
 357
 358                 // Close & re-open vcsa in case they have
 359                 // swapped virtual consoles
 360                 G.vcsa_fd = xopen(vcsa_name, O_RDONLY);
 361                 xread(G.vcsa_fd, &G.info, 4);
 362                 if (G.size != (G.info.rows * G.info.lines * 2)) {
 363                         cleanup(1);
 364                 }
 365                 i = G.width;
 366                 j = G.height;
 367                 get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
 368                 if ((option_mask32 & FLAG(f))) {
 369                         int nx = G.info.cursor_x - G.width + 1;
 370                         int ny = G.info.cursor_y - G.height + 1;
 371
 372                         if (G.info.cursor_x < G.x) {
 373                                 G.x = G.info.cursor_x;
 374                                 i = 0;  // force refresh
 375                         }
 376                         if (nx > G.x) {
 377                                 G.x = nx;
 378                                 i = 0;  // force refresh
 379                         }
 380                         if (G.info.cursor_y < G.y) {
 381                                 G.y = G.info.cursor_y;
 382                                 i = 0;  // force refresh
 383                         }
 384                         if (ny > G.y) {
 385                                 G.y = ny;
 386                                 i = 0;  // force refresh
 387                         }
 388                 }
 389
 390                 // Scan console data and redraw our tty where needed
 391                 screen_read_close();
 392                 if (i != G.width || j != G.height) {
 393                         clrscr();
 394                         screen_dump();
 395                 }
 396                 else for (i = 0; i < G.info.lines; i++) {
 397                         char *last = last;
 398                         char *first = NULL;
 399                         int iy = i - G.y;
 400
 401                         if (iy >= (int) G.height)
 402                                 break;
 403                         for (j = 0; j < G.info.rows; j++) {
 404                                 last = data;
 405                                 if (DATA(data) != DATA(old) && iy >= 0) {
 406                                         unsigned jx = j - G.x;
 407
 408                                         last = NULL;
 409                                         if (first == NULL && jx < G.width) {
 410                                                 first = data;
 411                                                 gotoxy(jx, iy);
 412                                         }
 413                                 }
 414                                 NEXT(old);
 415                                 NEXT(data);
 416                         }
 417                         if (first == NULL)
 418                                 continue;
 419                         if (last == NULL)
 420                                 last = data;
 421
 422                         // Write the data to the screen
 423                         for (; first < last; NEXT(first))
 424                                 screen_char(first);
 425                 }
 426                 curmove();
 427
 428                 // Wait for local user keypresses
 429                 pfd.fd = G.kbd_fd;
 430                 pfd.events = POLLIN;
 431                 bytes_read = 0;
 432                 switch (poll(&pfd, 1, poll_timeout_ms)) {
 433                         char *k;
 434                 case -1:
 435                         if (errno != EINTR)
 436                                 cleanup(1);
 437                         break;
 438                 case 0:
 439                         if (++G.nokeys >= 4)
 440                                 G.nokeys = G.escape_count = 0;
 441                         break;
 442                 default:
 443                         // Read the keys pressed
 444                         k = keybuf + G.key_count;
 445                         bytes_read = read(G.kbd_fd, k, sizeof(keybuf) - G.key_count);
 446                         if (bytes_read < 0)
 447                                 cleanup(1);
 448
 449                         // Do exit processing
 450                         for (i = 0; i < bytes_read; i++) {
 451                                 if (k[i] != '\033') G.escape_count = 0;
 452                                 else if (++G.escape_count >= 3)
 453                                         cleanup(0);
 454                         }
 455                 }
 456                 poll_timeout_ms = 250;
 457
 458                 // Insert all keys pressed into the virtual console's input
 459                 // buffer.  Don't do this if the virtual console is in scan
 460                 // code mode - giving ASCII characters to a program expecting
 461                 // scan codes will confuse it.
 462                 if (!(option_mask32 & FLAG(v)) && G.escape_count == 0) {
 463                         int handle, result;
 464                         long kbd_mode;
 465
 466                         G.key_count += bytes_read;
 467                         handle = xopen(tty_name, O_WRONLY);
 468                         result = ioctl(handle, KDGKBMODE, &kbd_mode);
 469                         if (result == -1)
 470                                 /* nothing */;
 471                         else if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE)
 472                                 G.key_count = 0; // scan code mode
 473                         else {
 474                                 for (i = 0; i < G.key_count && result != -1; i++)
 475                                         result = ioctl(handle, TIOCSTI, keybuf + i);
 476                                 G.key_count -= i;
 477                                 if (G.key_count)
 478                                         memmove(keybuf, keybuf + i, G.key_count);
 479                                 // If there is an application on console which reacts
 480                                 // to keypresses, we need to make our first sleep
 481                                 // shorter to quickly redraw whatever it printed there.
 482                                 poll_timeout_ms = 20;
 483                         }
 484                         // Close & re-open tty in case they have
 485                         // swapped virtual consoles
 486                         close(handle);
 487
 488                         // We sometimes get spurious IO errors on the TTY
 489                         // as programs close and re-open it
 490                         if (result != -1)
 491                                 G.ioerror_count = 0;
 492                         else if (errno != EIO || ++G.ioerror_count > 4)
 493                                 cleanup(1);
 494                 }
 495         }
 496 }