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         char 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         if (!BW && G.last_attr != ATTR(data)) {
 116                 //                            BLGCRMOW
 117                 static const char color[8] = "04261537";
 118
 119                 printf("\033[%c;4%c;3%cm",
 120                         (ATTR(data) & 8) ? '1'  // bold
 121                                          : '0', // defaults
 122                         color[(ATTR(data) >> 4) & 7], color[ATTR(data) & 7]);
 123                 G.last_attr = ATTR(data);
 124         }
 125         bb_putchar(CHAR(data));
 126 }
 127
 128 #define clrscr()  printf("\033[1;1H" "\033[0J")
 129 #define curoff()  printf("\033[?25l")
 130
 131 static void curon(void)
 132 {
 133         printf("\033[?25h");
 134 }
 135
 136 static void gotoxy(int row, int line)
 137 {
 138         printf("\033[%u;%uH", line + 1, row + 1);
 139 }
 140
 141 static void screen_dump(void)
 142 {
 143         int linefeed_cnt;
 144         int line, row;
 145         int linecnt = G.info.lines - G.y;
 146         char *data = G.data + G.current + (2 * G.y * G.info.rows);
 147
 148         linefeed_cnt = 0;
 149         for (line = 0; line < linecnt && line < G.height; line++) {
 150                 int space_cnt = 0;
 151                 for (row = 0; row < G.info.rows; row++, NEXT(data)) {
 152                         unsigned tty_row = row - G.x; // if will catch row < G.x too
 153
 154                         if (tty_row >= G.width)
 155                                 continue;
 156                         space_cnt++;
 157                         if (BW && (CHAR(data) | ' ') == ' ')
 158                                 continue;
 159                         while (linefeed_cnt != 0) {
 160                                 bb_putchar('\r');
 161                                 bb_putchar('\n');
 162                                 linefeed_cnt--;
 163                         }
 164                         while (--space_cnt)
 165                                 bb_putchar(' ');
 166                         screen_char(data);
 167                 }
 168                 linefeed_cnt++;
 169         }
 170 }
 171
 172 static void curmove(void)
 173 {
 174         unsigned cx = G.info.cursor_x - G.x;
 175         unsigned cy = G.info.cursor_y - G.y;
 176
 177         if (cx >= G.width || cy >= G.height) {
 178                 curoff();
 179         } else {
 180                 curon();
 181                 gotoxy(cx, cy);
 182         }
 183         fflush_all();
 184 }
 185
 186 static void cleanup(int code)
 187 {
 188         curon();
 189         fflush_all();
 190         tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
 191         if (ENABLE_FEATURE_CLEAN_UP) {
 192                 free(ptr_to_globals);
 193                 close(G.kbd_fd);
 194         }
 195         // Reset attributes
 196         if (!BW)
 197                 printf("\033[0m");
 198         bb_putchar('\n');
 199         if (code > 1)
 200                 kill_myself_with_sig(code); // does not return
 201         exit(code);
 202 }
 203
 204 static void get_initial_data(const char* vcsa_name)
 205 {
 206         int size;
 207         G.vcsa_fd = xopen(vcsa_name, O_RDONLY);
 208         xread(G.vcsa_fd, &G.info, 4);
 209         G.size = size = G.info.rows * G.info.lines * 2;
 210         G.width = G.height = UINT_MAX;
 211         G.data = xzalloc(2 * size);
 212         screen_read_close();
 213 }
 214
 215 static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
 216 {
 217         int fd = open(name, O_RDONLY);
 218         if (fd != -1)
 219                 close(fd);
 220         else if (errno == ENOENT)
 221                 mknod(name, S_IFCHR | 0660, dev);
 222 }
 223
 224 static NOINLINE void start_shell_in_child(const char* tty_name)
 225 {
 226         int pid = vfork();
 227         if (pid < 0) {
 228                 bb_perror_msg_and_die("vfork");
 229         }
 230         if (pid == 0) {
 231                 struct termios termchild;
 232                 char *shell = getenv("SHELL");
 233
 234                 if (!shell)
 235                         shell = (char *) DEFAULT_SHELL;
 236                 signal(SIGHUP, SIG_IGN);
 237                 // set tty as a controlling tty
 238                 setsid();
 239                 // make tty to be input, output, error
 240                 close(0);
 241                 xopen(tty_name, O_RDWR); // uses fd 0
 242                 xdup2(0, 1);
 243                 xdup2(0, 2);
 244                 ioctl(0, TIOCSCTTY, 1);
 245                 tcsetpgrp(0, getpid());
 246                 tcgetattr(0, &termchild);
 247                 termchild.c_lflag |= ECHO;
 248                 termchild.c_oflag |= ONLCR | XTABS;
 249                 termchild.c_iflag |= ICRNL;
 250                 termchild.c_iflag &= ~IXOFF;
 251                 tcsetattr_stdin_TCSANOW(&termchild);
 252                 execl(shell, shell, "-i", (char *) NULL);
 253                 bb_simple_perror_msg_and_die(shell);
 254         }
 255 }
 256
 257 int conspy_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
 258 int conspy_main(int argc UNUSED_PARAM, char **argv)
 259 {
 260         char vcsa_name[sizeof("/dev/vcsa") + 2];
 261         char tty_name[sizeof("/dev/tty") + 2];
 262 #define keybuf bb_common_bufsiz1
 263         struct termios termbuf;
 264         unsigned opts;
 265         unsigned ttynum;
 266         int poll_timeout_ms;
 267 #if ENABLE_LONG_OPTS
 268         static const char getopt_longopts[] ALIGN1 =
 269                 "viewonly\0"     No_argument "v"
 270                 "createdevice\0" No_argument "c"
 271                 "session\0"      No_argument "s"
 272                 "nocolors\0"     No_argument "n"
 273                 "dump\0"         No_argument "d"
 274                 "follow\0"       No_argument "f"
 275                 ;
 276
 277         applet_long_options = getopt_longopts;
 278 #endif
 279         INIT_G();
 280
 281         opt_complementary = "x+:y+"; // numeric params
 282         opts = getopt32(argv, "vcsndfx:y:", &G.x, &G.y);
 283         argv += optind;
 284         ttynum = 0;
 285         if (argv[0]) {
 286                 ttynum = xatou_range(argv[0], 0, 63);
 287         }
 288         sprintf(vcsa_name, "/dev/vcsa%u", ttynum);
 289         sprintf(tty_name, "%s%u", "/dev/tty", ttynum);
 290         if (opts & FLAG(c)) {
 291                 if ((opts & (FLAG(s)|FLAG(v))) != FLAG(v))
 292                         create_cdev_if_doesnt_exist(tty_name, makedev(4, ttynum));
 293                 create_cdev_if_doesnt_exist(vcsa_name, makedev(7, 128 + ttynum));
 294         }
 295         if ((opts & FLAG(s)) && ttynum) {
 296                 start_shell_in_child(tty_name);
 297         }
 298
 299         get_initial_data(vcsa_name);
 300         G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
 301         if (opts & FLAG(d)) {
 302                 screen_dump();
 303                 bb_putchar('\n');
 304                 if (ENABLE_FEATURE_CLEAN_UP) {
 305                         free(ptr_to_globals);
 306                         close(G.kbd_fd);
 307                 }
 308                 return 0;
 309         }
 310
 311         bb_signals(BB_FATAL_SIGS, cleanup);
 312         // All characters must be passed through to us unaltered
 313         tcgetattr(G.kbd_fd, &G.term_orig);
 314         termbuf = G.term_orig;
 315         termbuf.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
 316         termbuf.c_oflag &= ~(OPOST);
 317         termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
 318         termbuf.c_cc[VMIN] = 1;
 319         termbuf.c_cc[VTIME] = 0;
 320         tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
 321         poll_timeout_ms = 250;
 322         while (1) {
 323                 struct pollfd pfd;
 324                 int bytes_read;
 325                 int i, j;
 326                 char *data, *old;
 327
 328                 old = G.data + G.current;
 329                 G.current = G.size - G.current;
 330                 data = G.data + G.current;
 331
 332                 // Close & re-open vcsa in case they have
 333                 // swapped virtual consoles
 334                 G.vcsa_fd = xopen(vcsa_name, O_RDONLY);
 335                 xread(G.vcsa_fd, &G.info, 4);
 336                 if (G.size != (G.info.rows * G.info.lines * 2)) {
 337                         cleanup(1);
 338                 }
 339                 i = G.width;
 340                 j = G.height;
 341                 get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
 342                 if ((option_mask32 & FLAG(f))) {
 343                         int nx = G.info.cursor_x - G.width + 1;
 344                         int ny = G.info.cursor_y - G.height + 1;
 345
 346                         if (G.info.cursor_x < G.x) {
 347                                 G.x = G.info.cursor_x;
 348                                 i = 0;  // force refresh
 349                         }
 350                         if (nx > G.x) {
 351                                 G.x = nx;
 352                                 i = 0;  // force refresh
 353                         }
 354                         if (G.info.cursor_y < G.y) {
 355                                 G.y = G.info.cursor_y;
 356                                 i = 0;  // force refresh
 357                         }
 358                         if (ny > G.y) {
 359                                 G.y = ny;
 360                                 i = 0;  // force refresh
 361                         }
 362                 }
 363
 364                 // Scan console data and redraw our tty where needed
 365                 screen_read_close();
 366                 if (i != G.width || j != G.height) {
 367                         clrscr();
 368                         screen_dump();
 369                 }
 370                 else for (i = 0; i < G.info.lines; i++) {
 371                         char *last = last;
 372                         char *first = NULL;
 373                         int iy = i - G.y;
 374
 375                         if (iy >= (int) G.height)
 376                                 break;
 377                         for (j = 0; j < G.info.rows; j++) {
 378                                 last = data;
 379                                 if (DATA(data) != DATA(old) && iy >= 0) {
 380                                         unsigned jx = j - G.x;
 381
 382                                         last = NULL;
 383                                         if (first == NULL && jx < G.width) {
 384                                                 first = data;
 385                                                 gotoxy(jx, iy);
 386                                         }
 387                                 }
 388                                 NEXT(old);
 389                                 NEXT(data);
 390                         }
 391                         if (first == NULL)
 392                                 continue;
 393                         if (last == NULL)
 394                                 last = data;
 395
 396                         // Write the data to the screen
 397                         for (; first < last; NEXT(first))
 398                                 screen_char(first);
 399                 }
 400                 curmove();
 401
 402                 // Wait for local user keypresses
 403                 pfd.fd = G.kbd_fd;
 404                 pfd.events = POLLIN;
 405                 bytes_read = 0;
 406                 switch (poll(&pfd, 1, poll_timeout_ms)) {
 407                         char *k;
 408                 case -1:
 409                         if (errno != EINTR)
 410                                 cleanup(1);
 411                         break;
 412                 case 0:
 413                         if (++G.nokeys >= 4)
 414                                 G.nokeys = G.escape_count = 0;
 415                         break;
 416                 default:
 417                         // Read the keys pressed
 418                         k = keybuf + G.key_count;
 419                         bytes_read = read(G.kbd_fd, k, sizeof(keybuf) - G.key_count);
 420                         if (bytes_read < 0)
 421                                 cleanup(1);
 422
 423                         // Do exit processing
 424                         for (i = 0; i < bytes_read; i++) {
 425                                 if (k[i] != '\033') G.escape_count = 0;
 426                                 else if (++G.escape_count >= 3)
 427                                         cleanup(0);
 428                         }
 429                 }
 430                 poll_timeout_ms = 250;
 431
 432                 // Insert all keys pressed into the virtual console's input
 433                 // buffer.  Don't do this if the virtual console is in scan
 434                 // code mode - giving ASCII characters to a program expecting
 435                 // scan codes will confuse it.
 436                 if (!(option_mask32 & FLAG(v)) && G.escape_count == 0) {
 437                         int handle, result;
 438                         long kbd_mode;
 439
 440                         G.key_count += bytes_read;
 441                         handle = xopen(tty_name, O_WRONLY);
 442                         result = ioctl(handle, KDGKBMODE, &kbd_mode);
 443                         if (result == -1)
 444                                 /* nothing */;
 445                         else if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE)
 446                                 G.key_count = 0; // scan code mode
 447                         else {
 448                                 for (i = 0; i < G.key_count && result != -1; i++)
 449                                         result = ioctl(handle, TIOCSTI, keybuf + i);
 450                                 G.key_count -= i;
 451                                 if (G.key_count)
 452                                         memmove(keybuf, keybuf + i, G.key_count);
 453                                 // If there is an application on console which reacts
 454                                 // to keypresses, we need to make our first sleep
 455                                 // shorter to quickly redraw whatever it printed there.
 456                                 poll_timeout_ms = 20;
 457                         }
 458                         // Close & re-open tty in case they have
 459                         // swapped virtual consoles
 460                         close(handle);
 461
 462                         // We sometimes get spurious IO errors on the TTY
 463                         // as programs close and re-open it
 464                         if (result != -1)
 465                                 G.ioerror_count = 0;
 466                         else if (errno != EIO || ++G.ioerror_count > 4)
 467                                 cleanup(1);
 468                 }
 469         }
 470 }