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         struct screen_info info;
  67         struct termios term_orig;
  68 };
  69
  70 #define G (*ptr_to_globals)
  71 #define INIT_G() do { \
  72         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
  73 } while (0)
  74
  75 enum {
  76         FLAG_v,  // view only
  77         FLAG_c,  // create device if need
  78         FLAG_s,  // session
  79         FLAG_n,  // no colors
  80         FLAG_d,  // dump screen
  81         FLAG_f,  // follow cursor
  82 };
  83 #define FLAG(x) (1 << FLAG_##x)
  84 #define BW (option_mask32 & FLAG(n))
  85
  86 static void screen_read_close(int fd, char *data)
  87 {
  88         unsigned i, j;
  89
  90         xread(fd, data, G.size);
  91         G.last_attr = 0;
  92         for (i = 0; i < G.info.lines; i++) {
  93                 for (j = 0; j < G.info.rows; j++, NEXT(data)) {
  94                         unsigned x = j - G.x; // if will catch j < G.x too
  95                         unsigned y = i - G.y; // if will catch i < G.y too
  96
  97                         if (CHAR(data) < ' ')
  98                                 CHAR(data) = ' ';
  99                         if (y >= G.height || x >= G.width)
 100                                 DATA(data) = 0;
 101                 }
 102         }
 103         close(fd);
 104 }
 105
 106 static void screen_char(char *data)
 107 {
 108         if (!BW && G.last_attr != ATTR(data)) {
 109                 //                            BLGCRMOW
 110                 static const char color[8] = "04261537";
 111
 112                 printf("\033[%c;4%c;3%cm",
 113                         (ATTR(data) & 8) ? '1'  // bold
 114                                          : '0', // defaults
 115                         color[(ATTR(data) >> 4) & 7], color[ATTR(data) & 7]);
 116                 G.last_attr = ATTR(data);
 117         }
 118         bb_putchar(CHAR(data));
 119 }
 120
 121 #define clrscr()  printf("\033[1;1H" "\033[0J")
 122 #define curoff()  printf("\033[?25l")
 123
 124 static void curon(void)
 125 {
 126         printf("\033[?25h");
 127 }
 128
 129 static void gotoxy(int row, int line)
 130 {
 131         printf("\033[%u;%uH", line + 1, row + 1);
 132 }
 133
 134 static void screen_dump(char *data)
 135 {
 136         int linefeed_cnt;
 137         int line, row;
 138         int linecnt = G.info.lines - G.y;
 139
 140         data += 2 * G.y * G.info.rows;
 141         linefeed_cnt = 0;
 142         for (line = 0; line < linecnt && line < G.height; line++) {
 143                 int space_cnt = 0;
 144                 for (row = 0; row < G.info.rows; row++, NEXT(data)) {
 145                         unsigned tty_row = row - G.x; // if will catch row < G.x too
 146
 147                         if (tty_row >= G.width)
 148                                 continue;
 149                         space_cnt++;
 150                         if (BW && (CHAR(data) | ' ') == ' ')
 151                                 continue;
 152                         while (linefeed_cnt != 0) {
 153                                 bb_putchar('\r');
 154                                 bb_putchar('\n');
 155                                 linefeed_cnt--;
 156                         }
 157                         while (--space_cnt)
 158                                 bb_putchar(' ');
 159                         screen_char(data);
 160                 }
 161                 linefeed_cnt++;
 162         }
 163 }
 164
 165 static void curmove(void)
 166 {
 167         unsigned cx = G.info.cursor_x - G.x;
 168         unsigned cy = G.info.cursor_y - G.y;
 169
 170         if (cx >= G.width || cy >= G.height) {
 171                 curoff();
 172         } else {
 173                 curon();
 174                 gotoxy(cx, cy);
 175         }
 176         fflush_all();
 177 }
 178
 179 static void cleanup(int code)
 180 {
 181         curon();
 182         fflush_all();
 183         tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
 184         if (ENABLE_FEATURE_CLEAN_UP) {
 185                 free(ptr_to_globals);
 186                 close(G.kbd_fd);
 187         }
 188         // Reset attributes
 189         if (!BW)
 190                 printf("\033[0m");
 191         bb_putchar('\n');
 192         if (code > 1)
 193                 kill_myself_with_sig(code); // does not return
 194         exit(code);
 195 }
 196
 197 static void get_initial_data(const char* vcsa_name)
 198 {
 199         int size;
 200         int fd = xopen(vcsa_name, O_RDONLY);
 201         xread(fd, &G.info, 4);
 202         G.size = size = G.info.rows * G.info.lines * 2;
 203         G.width = G.height = UINT_MAX;
 204         G.data = xzalloc(2 * size);
 205         screen_read_close(fd, G.data);
 206 }
 207
 208 static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
 209 {
 210         int fd = open(name, O_RDONLY);
 211         if (fd != -1)
 212                 close(fd);
 213         else if (errno == ENOENT)
 214                 mknod(name, S_IFCHR | 0660, dev);
 215 }
 216
 217 static NOINLINE void start_shell_in_child(const char* tty_name)
 218 {
 219         int pid = vfork();
 220         if (pid < 0) {
 221                 bb_perror_msg_and_die("vfork");
 222         }
 223         if (pid == 0) {
 224                 struct termios termchild;
 225                 char *shell = getenv("SHELL");
 226
 227                 if (!shell)
 228                         shell = (char *) DEFAULT_SHELL;
 229                 signal(SIGHUP, SIG_IGN);
 230                 // set tty as a controlling tty
 231                 setsid();
 232                 // make tty to be input, output, error
 233                 close(0);
 234                 xopen(tty_name, O_RDWR); // uses fd 0
 235                 xdup2(0, 1);
 236                 xdup2(0, 2);
 237                 ioctl(0, TIOCSCTTY, 1);
 238                 tcsetpgrp(0, getpid());
 239                 tcgetattr(0, &termchild);
 240                 termchild.c_lflag |= ECHO;
 241                 termchild.c_oflag |= ONLCR | XTABS;
 242                 termchild.c_iflag |= ICRNL;
 243                 termchild.c_iflag &= ~IXOFF;
 244                 tcsetattr_stdin_TCSANOW(&termchild);
 245                 execl(shell, shell, "-i", (char *) NULL);
 246                 bb_simple_perror_msg_and_die(shell);
 247         }
 248 }
 249
 250 int conspy_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
 251 int conspy_main(int argc UNUSED_PARAM, char **argv)
 252 {
 253         char *buffer[2];
 254         char vcsa_name[sizeof("/dev/vcsa") + 2];
 255         char tty_name[sizeof("/dev/tty") + 2];
 256 #define keybuf bb_common_bufsiz1
 257         struct termios termbuf;
 258         unsigned opts;
 259         unsigned ttynum;
 260         int poll_timeout_ms;
 261         int current;
 262         int ioerror_count;
 263         int key_count;
 264         int escape_count;
 265         int nokeys;
 266 #if ENABLE_LONG_OPTS
 267         static const char getopt_longopts[] ALIGN1 =
 268                 "viewonly\0"     No_argument "v"
 269                 "createdevice\0" No_argument "c"
 270                 "session\0"      No_argument "s"
 271                 "nocolors\0"     No_argument "n"
 272                 "dump\0"         No_argument "d"
 273                 "follow\0"       No_argument "f"
 274                 ;
 275
 276         applet_long_options = getopt_longopts;
 277 #endif
 278         INIT_G();
 279         strcpy(vcsa_name, "/dev/vcsa");
 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                 sprintf(vcsa_name + sizeof("/dev/vcsa")-1, "%u", ttynum);
 288         }
 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(G.data);
 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         buffer[0] = G.data;
 322         buffer[1] = G.data + G.size;
 323         poll_timeout_ms = 250;
 324         ioerror_count = key_count = escape_count = nokeys = current = 0;
 325         while (1) {
 326                 struct pollfd pfd;
 327                 int vcsa_handle;
 328                 int bytes_read;
 329                 int i, j;
 330                 int next = 1 - current;
 331                 char *data = buffer[next];
 332                 char *old  = buffer[current];
 333
 334                 // Close & re-open vcsa in case they have
 335                 // swapped virtual consoles
 336                 vcsa_handle = xopen(vcsa_name, O_RDONLY);
 337                 xread(vcsa_handle, &G.info, 4);
 338                 if (G.size != (G.info.rows * G.info.lines * 2)) {
 339                         cleanup(1);
 340                 }
 341                 i = G.width;
 342                 j = G.height;
 343                 get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
 344                 if ((option_mask32 & FLAG(f))) {
 345                         int nx = G.info.cursor_x - G.width + 1;
 346                         int ny = G.info.cursor_y - G.height + 1;
 347
 348                         if (G.info.cursor_x < G.x) {
 349                                 G.x = G.info.cursor_x;
 350                                 i = 0;  // force refresh
 351                         }
 352                         if (nx > G.x) {
 353                                 G.x = nx;
 354                                 i = 0;  // force refresh
 355                         }
 356                         if (G.info.cursor_y < G.y) {
 357                                 G.y = G.info.cursor_y;
 358                                 i = 0;  // force refresh
 359                         }
 360                         if (ny > G.y) {
 361                                 G.y = ny;
 362                                 i = 0;  // force refresh
 363                         }
 364                 }
 365
 366                 // Scan console data and redraw our tty where needed
 367                 screen_read_close(vcsa_handle, data);
 368                 if (i != G.width || j != G.height) {
 369                         clrscr();
 370                         screen_dump(data);
 371                 }
 372                 else for (i = 0; i < G.info.lines; i++) {
 373                         char *last = last;
 374                         char *first = NULL;
 375                         int iy = i - G.y;
 376
 377                         if (iy >= (int) G.height)
 378                                 break;
 379                         for (j = 0; j < G.info.rows; j++) {
 380                                 last = data;
 381                                 if (DATA(data) != DATA(old) && iy >= 0) {
 382                                         unsigned jx = j - G.x;
 383
 384                                         last = NULL;
 385                                         if (first == NULL && jx < G.width) {
 386                                                 first = data;
 387                                                 gotoxy(jx, iy);
 388                                         }
 389                                 }
 390                                 NEXT(old);
 391                                 NEXT(data);
 392                         }
 393                         if (first == NULL)
 394                                 continue;
 395                         if (last == NULL)
 396                                 last = data;
 397
 398                         // Write the data to the screen
 399                         for (; first < last; NEXT(first))
 400                                 screen_char(first);
 401                 }
 402                 current = next;
 403                 curmove();
 404
 405                 // Wait for local user keypresses
 406                 pfd.fd = G.kbd_fd;
 407                 pfd.events = POLLIN;
 408                 bytes_read = 0;
 409                 switch (poll(&pfd, 1, poll_timeout_ms)) {
 410                 case -1:
 411                         if (errno != EINTR)
 412                                 cleanup(1);
 413                         break;
 414                 case 0:
 415                         if (++nokeys >= 4)
 416                                 nokeys = escape_count = 0;
 417                         break;
 418                 default:
 419                         // Read the keys pressed
 420                         bytes_read = read(G.kbd_fd, keybuf + key_count,
 421                                         sizeof(keybuf) - key_count);
 422                         if (bytes_read < 0)
 423                                 cleanup(1);
 424
 425                         // Do exit processing
 426                         for (i = 0; i < bytes_read; i++) {
 427                                 if (keybuf[key_count + i] != '\033')
 428                                         escape_count = 0;
 429                                 else if (++escape_count >= 3)
 430                                         cleanup(0);
 431                         }
 432                 }
 433                 poll_timeout_ms = 250;
 434
 435                 // Insert all keys pressed into the virtual console's input
 436                 // buffer.  Don't do this if the virtual console is in scan
 437                 // code mode - giving ASCII characters to a program expecting
 438                 // scan codes will confuse it.
 439                 if (!(option_mask32 & FLAG(v)) && escape_count == 0) {
 440                         int handle, result;
 441                         long kbd_mode;
 442
 443                         key_count += bytes_read;
 444                         handle = xopen(tty_name, O_WRONLY);
 445                         result = ioctl(handle, KDGKBMODE, &kbd_mode);
 446                         if (result == -1)
 447                                 /* nothing */;
 448                         else if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE)
 449                                 key_count = 0; // scan code mode
 450                         else {
 451                                 for (i = 0; i < key_count && result != -1; i++)
 452                                         result = ioctl(handle, TIOCSTI, keybuf + i);
 453                                 key_count -= i;
 454                                 if (key_count)
 455                                         memmove(keybuf, keybuf + i, key_count);
 456                                 // If there is an application on console which reacts
 457                                 // to keypresses, we need to make our first sleep
 458                                 // shorter to quickly redraw whatever it printed there.
 459                                 poll_timeout_ms = 20;
 460                         }
 461                         // Close & re-open tty in case they have
 462                         // swapped virtual consoles
 463                         close(handle);
 464
 465                         // We sometimes get spurious IO errors on the TTY
 466                         // as programs close and re-open it
 467                         if (result != -1)
 468                                 ioerror_count = 0;
 469                         else if (errno != EIO || ++ioerror_count > 4)
 470                                 cleanup(1);
 471                 }
 472         }
 473 }