1 /* vi: set sw=4 ts=4: */
3 * A text-mode VNC like program for Linux virtual terminals.
5 * pascal.bellard@ads-lu.com
7 * Based on Russell Stuart's conspy.c
8 * http://ace-host.stuart.id.au/russell/files/conspy.c
10 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
13 //applet:IF_CONSPY(APPLET(conspy, BB_DIR_BIN, BB_SUID_DROP))
15 //kbuild:lib-$(CONFIG_CONSPY) += conspy.o
17 //config:config CONSPY
18 //config: bool "conspy"
20 //config: select PLATFORM_LINUX
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
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."
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"
51 #define DEV_TTY "/dev/tty"
52 #define DEV_VCSA "/dev/vcsa"
55 unsigned char lines, cols, cursor_x, cursor_y;
58 #define CHAR(x) (*(uint8_t*)(x))
59 #define ATTR(x) (((uint8_t*)(x))[1])
60 #define NEXT(x) ((x) += 2)
61 #define DATA(x) (*(uint16_t*)(x))
73 int first_line_offset;
75 // cached local tty parameters
80 smallint curoff; // unknown:0 cursor on:-1 cursor off:1
81 char attrbuf[sizeof("0;1;5;30;40m")];
83 struct screen_info remote;
84 // saved local tty terminfo
85 struct termios term_orig;
86 char vcsa_name[sizeof(DEV_VCSA "NN")];
89 #define G (*ptr_to_globals)
90 #define INIT_G() do { \
91 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
92 G.width = G.height = UINT_MAX; \
98 FLAG_c, // create device if need
102 FLAG_d, // dump screen
103 FLAG_f, // follow cursor
104 FLAG_F, // framebuffer
106 #define FLAG(x) (1 << FLAG_##x)
107 #define BW (option_mask32 & FLAG(n))
109 static void putcsi(const char *s)
111 fputs(ESC"[", stdout);
115 static void clrscr(void)
117 // Home, clear till end of screen
118 putcsi("1;1H" ESC"[J");
122 static void set_cursor(int state)
124 if (G.curoff != state) {
127 bb_putchar("h?l"[1 + state]);
131 static void gotoxy(int col, int line)
133 if (G.col != col || G.line != line) {
136 printf(ESC"[%u;%uH", line + 1, col + 1);
140 static void cleanup(int code) NORETURN;
141 static void cleanup(int code)
143 set_cursor(CURSOR_ON);
144 tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
145 if (ENABLE_FEATURE_CLEAN_UP) {
152 if (code > EXIT_FAILURE)
153 kill_myself_with_sig(code);
157 static void screen_read_close(void)
163 // Close & re-open vcsa in case they have swapped virtual consoles
164 vcsa_fd = xopen(G.vcsa_name, O_RDONLY);
165 xread(vcsa_fd, &G.remote, 4);
166 i = G.remote.cols * 2;
167 G.first_line_offset = G.y * i;
169 if (G.data == NULL) {
171 G.data = xzalloc(2 * i);
174 cleanup(EXIT_FAILURE);
176 data = G.data + G.current;
177 xread(vcsa_fd, data, G.size);
179 for (i = 0; i < G.remote.lines; i++) {
180 for (j = 0; j < G.remote.cols; j++, NEXT(data)) {
181 unsigned x = j - G.x; // if will catch j < G.x too
182 unsigned y = i - G.y; // if will catch i < G.y too
184 if (y >= G.height || x >= G.width)
187 uint8_t ch = CHAR(data);
189 CHAR(data) = ch | 0x40;
197 static void screen_char(char *data)
201 uint8_t attr = ATTR(data);
203 if (option_mask32 & FLAG(F)) {
206 attr_diff = G.last_attr ^ attr;
208 // Attribute layout for VGA compatible text videobuffer:
214 // 00000000 <- lsb bit on the right
215 // bold text / text 8th bit
219 // TODO: apparently framebuffer-based console uses different layout
220 // (bug? attempt to get 8th text bit in better position?)
225 // 00000000 <- lsb bit on the right
231 // converting RGB color bit triad to BGR:
232 static const char color[8] = "04261537";
233 const uint8_t fg_mask = 0x07, bold_mask = 0x08;
234 const uint8_t bg_mask = 0x70, blink_mask = 0x80;
239 // (G.last_attr & ~attr) has 1 only where
240 // G.last_attr has 1 but attr has 0.
241 // Here we check whether we have transition
242 // bold->non-bold or blink->non-blink:
243 if (G.last_attr < 0 // initial value
244 || ((G.last_attr & ~attr) & (bold_mask | blink_mask)) != 0
246 *ptr++ = '0'; // "reset all attrs"
248 // must set fg & bg, maybe need to set bold or blink:
249 attr_diff = attr | ~(bold_mask | blink_mask);
252 if (attr_diff & bold_mask) {
256 if (attr_diff & blink_mask) {
260 if (attr_diff & fg_mask) {
262 *ptr++ = color[attr & fg_mask];
265 if (attr_diff & bg_mask) {
267 *ptr++ = color[(attr & bg_mask) >> 4];
268 ptr++; // last attribute
270 if (ptr != G.attrbuf) {
281 static void screen_dump(void)
285 int linecnt = G.remote.lines - G.y;
286 char *data = G.data + G.current + G.first_line_offset;
289 for (line = 0; line < linecnt && line < G.height; line++) {
291 for (col = 0; col < G.remote.cols; col++, NEXT(data)) {
292 unsigned tty_col = col - G.x; // if will catch col < G.x too
294 if (tty_col >= G.width)
297 if (BW && CHAR(data) == ' ')
299 while (linefeed_cnt != 0) {
300 //bb_putchar('\r'); - tty driver does it for us
312 static void curmove(void)
314 unsigned cx = G.remote.cursor_x - G.x;
315 unsigned cy = G.remote.cursor_y - G.y;
316 int cursor = CURSOR_OFF;
318 if (cx < G.width && cy < G.height) {
325 static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
327 int fd = open(name, O_RDONLY);
330 else if (errno == ENOENT)
331 mknod(name, S_IFCHR | 0660, dev);
334 static NOINLINE void start_shell_in_child(const char* tty_name)
338 struct termios termchild;
339 const char *shell = get_shell_name();
341 signal(SIGHUP, SIG_IGN);
342 // set tty as a controlling tty
344 // make tty to be input, output, error
346 xopen(tty_name, O_RDWR); // uses fd 0
349 ioctl(0, TIOCSCTTY, 1);
350 tcsetpgrp(0, getpid());
351 tcgetattr(0, &termchild);
352 termchild.c_lflag |= ECHO;
353 termchild.c_oflag |= ONLCR | XTABS;
354 termchild.c_iflag |= ICRNL;
355 termchild.c_iflag &= ~IXOFF;
356 tcsetattr_stdin_TCSANOW(&termchild);
357 execl(shell, shell, "-i", (char *) NULL);
358 bb_simple_perror_msg_and_die(shell);
362 int conspy_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
363 int conspy_main(int argc UNUSED_PARAM, char **argv)
365 char tty_name[sizeof(DEV_TTY "NN")];
366 #define keybuf bb_common_bufsiz1
367 struct termios termbuf;
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"
383 applet_long_options = getopt_longopts;
386 strcpy(G.vcsa_name, DEV_VCSA);
388 opt_complementary = "x+:y+"; // numeric params
389 opts = getopt32(argv, "vcQsndfFx:y:", &G.x, &G.y);
393 ttynum = xatou_range(argv[0], 0, 63);
394 sprintf(G.vcsa_name + sizeof(DEV_VCSA)-1, "%u", ttynum);
396 sprintf(tty_name, "%s%u", DEV_TTY, ttynum);
397 if (opts & FLAG(c)) {
398 if ((opts & (FLAG(s)|FLAG(v))) != FLAG(v))
399 create_cdev_if_doesnt_exist(tty_name, makedev(4, ttynum));
400 create_cdev_if_doesnt_exist(G.vcsa_name, makedev(7, 128 + ttynum));
402 if ((opts & FLAG(s)) && ttynum) {
403 start_shell_in_child(tty_name);
407 if (opts & FLAG(d)) {
413 bb_signals(BB_FATAL_SIGS, cleanup);
415 // All characters must be passed through to us unaltered
416 G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
417 tcgetattr(G.kbd_fd, &G.term_orig);
418 termbuf = G.term_orig;
419 termbuf.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
420 //termbuf.c_oflag &= ~(OPOST); - no, we still want \n -> \r\n
421 termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
422 termbuf.c_cc[VMIN] = 1;
423 termbuf.c_cc[VTIME] = 0;
424 tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
426 poll_timeout_ms = 250;
433 // in the first loop G.width = G.height = 0: refresh
436 get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
437 if (option_mask32 & FLAG(f)) {
438 int nx = G.remote.cursor_x - G.width + 1;
439 int ny = G.remote.cursor_y - G.height + 1;
441 if (G.remote.cursor_x < G.x) {
442 G.x = G.remote.cursor_x;
443 i = 0; // force refresh
447 i = 0; // force refresh
449 if (G.remote.cursor_y < G.y) {
450 G.y = G.remote.cursor_y;
451 i = 0; // force refresh
455 i = 0; // force refresh
459 // Scan console data and redraw our tty where needed
460 old = G.data + G.current;
461 G.current = G.size - G.current;
462 data = G.data + G.current;
464 if (i != G.width || j != G.height) {
468 // For each remote line
469 old += G.first_line_offset;
470 data += G.first_line_offset;
471 for (i = G.y; i < G.remote.lines; i++) {
472 char *first = NULL; // first char which needs updating
473 char *last = last; // last char which needs updating
474 unsigned iy = i - G.y;
478 for (j = 0; j < G.remote.cols; j++, NEXT(old), NEXT(data)) {
479 unsigned jx = j - G.x; // if will catch j >= G.x too
481 if (jx < G.width && DATA(data) != DATA(old)) {
490 // Rewrite updated data on the local screen
491 for (; first <= last; NEXT(first))
498 // Wait for local user keypresses
503 switch (poll(&pfd, 1, poll_timeout_ms)) {
511 G.nokeys = G.escape_count = 0;
514 // Read the keys pressed
515 k = keybuf + G.key_count;
516 bytes_read = read(G.kbd_fd, k, sizeof(keybuf) - G.key_count);
520 // Do exit processing
521 if (!(option_mask32 & FLAG(Q))) {
522 for (i = 0; i < bytes_read; i++) {
525 if (++G.escape_count >= 3)
526 cleanup(EXIT_SUCCESS);
530 poll_timeout_ms = 250;
531 if (option_mask32 & FLAG(v)) continue;
533 // Insert all keys pressed into the virtual console's input
534 // buffer. Don't do this if the virtual console is in scan
535 // code mode - giving ASCII characters to a program expecting
536 // scan codes will confuse it.
537 G.key_count += bytes_read;
538 if (G.escape_count == 0) {
542 handle = xopen(tty_name, O_WRONLY);
543 result = ioctl(handle, KDGKBMODE, &kbd_mode);
548 if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE) {
549 G.key_count = 0; // scan code mode
551 for (; G.key_count != 0; p++, G.key_count--) {
552 result = ioctl(handle, TIOCSTI, p);
554 memmove(keybuf, p, G.key_count);
557 // If there is an application on console which reacts
558 // to keypresses, we need to make our first sleep
559 // shorter to quickly redraw whatever it printed there.
560 poll_timeout_ms = 20;
563 // We sometimes get spurious IO errors on the TTY
564 // as programs close and re-open it
565 else if (errno != EIO || ++G.ioerror_count > 4) {
566 if (ENABLE_FEATURE_CLEAN_UP)
570 // Close & re-open tty in case they have
571 // swapped virtual consoles
576 cleanup(EXIT_FAILURE);