busybox/miscutils/conspy.c

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/* vi: set sw=4 ts=4: */
/*
* A text-mode VNC like program for Linux virtual terminals.
*
* pascal.bellard@ads-lu.com
*
* Based on Russell Stuart's conspy.c
* http://ace-host.stuart.id.au/russell/files/conspy.c
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config CONSPY
//config: bool "conspy"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: A text-mode VNC like program for Linux virtual terminals.
//config: example: conspy NUM shared access to console num
//config: or conspy -nd NUM screenshot of console num
//config: or conspy -cs NUM poor man's GNU screen like
//applet:IF_CONSPY(APPLET(conspy, BB_DIR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_CONSPY) += conspy.o
//usage:#define conspy_trivial_usage
//usage: "[-vcsndfFQ] [-x COL] [-y LINE] [CONSOLE_NO]"
//usage:#define conspy_full_usage "\n\n"
//usage: "A text-mode VNC like program for Linux virtual consoles."
//usage: "\nTo exit, quickly press ESC 3 times."
//usage: "\n"
//usage: "\n -v Don't send keystrokes to the console"
//usage: "\n -c Create missing /dev/{tty,vcsa}N"
//usage: "\n -s Open a SHELL session"
//usage: "\n -n Black & white"
//usage: "\n -d Dump console to stdout"
//usage: "\n -f Follow cursor"
//usage: "\n -F Assume console is on a framebuffer device"
//usage: "\n -Q Disable exit on ESC-ESC-ESC"
//usage: "\n -x COL Starting column"
//usage: "\n -y LINE Starting line"
#include "libbb.h"
#include "common_bufsiz.h"
#include <sys/kd.h>
#define ESC "\033"
#define CURSOR_ON -1
#define CURSOR_OFF 1
#define DEV_TTY "/dev/tty"
#define DEV_VCSA "/dev/vcsa"
struct screen_info {
unsigned char lines, cols, cursor_x, cursor_y;
};
#define CHAR(x) (*(uint8_t*)(x))
#define ATTR(x) (((uint8_t*)(x))[1])
#define NEXT(x) ((x) += 2)
#define DATA(x) (*(uint16_t*)(x))
struct globals {
char* data;
int size;
int x, y;
int kbd_fd;
int ioerror_count;
int key_count;
int escape_count;
int nokeys;
int current;
int first_line_offset;
int last_attr;
// cached local tty parameters
unsigned width;
unsigned height;
unsigned col;
unsigned line;
smallint curoff; // unknown:0 cursor on:-1 cursor off:1
char attrbuf[sizeof("0;1;5;30;40m")];
// remote console
struct screen_info remote;
// saved local tty terminfo
struct termios term_orig;
char vcsa_name[sizeof(DEV_VCSA "NN")];
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
G.width = G.height = UINT_MAX; \
G.last_attr--; \
} while (0)
enum {
FLAG_v, // view only
FLAG_c, // create device if need
FLAG_Q, // never exit
FLAG_s, // session
FLAG_n, // no colors
FLAG_d, // dump screen
FLAG_f, // follow cursor
FLAG_F, // framebuffer
};
#define FLAG(x) (1 << FLAG_##x)
#define BW (option_mask32 & FLAG(n))
static void putcsi(const char *s)
{
fputs(ESC"[", stdout);
fputs(s, stdout);
}
static void clrscr(void)
{
// Home, clear till end of screen
putcsi("1;1H" ESC"[J");
G.col = G.line = 0;
}
static void set_cursor(int state)
{
if (G.curoff != state) {
G.curoff = state;
putcsi("?25");
bb_putchar("h?l"[1 + state]);
}
}
static void gotoxy(int col, int line)
{
if (G.col != col || G.line != line) {
G.col = col;
G.line = line;
printf(ESC"[%u;%uH", line + 1, col + 1);
}
}
static void cleanup(int code) NORETURN;
static void cleanup(int code)
{
set_cursor(CURSOR_ON);
tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
if (ENABLE_FEATURE_CLEAN_UP) {
close(G.kbd_fd);
}
// Reset attributes
if (!BW)
putcsi("0m");
bb_putchar('\n');
if (code > EXIT_FAILURE)
kill_myself_with_sig(code);
exit(code);
}
static void screen_read_close(void)
{
unsigned i, j;
int vcsa_fd;
char *data;
// Close & re-open vcsa in case they have swapped virtual consoles
vcsa_fd = xopen(G.vcsa_name, O_RDONLY);
xread(vcsa_fd, &G.remote, 4);
i = G.remote.cols * 2;
G.first_line_offset = G.y * i;
i *= G.remote.lines;
if (G.data == NULL) {
G.size = i;
G.data = xzalloc(2 * i);
}
if (G.size != i) {
cleanup(EXIT_FAILURE);
}
data = G.data + G.current;
xread(vcsa_fd, data, G.size);
close(vcsa_fd);
for (i = 0; i < G.remote.lines; i++) {
for (j = 0; j < G.remote.cols; j++, NEXT(data)) {
unsigned x = j - G.x; // if will catch j < G.x too
unsigned y = i - G.y; // if will catch i < G.y too
if (y >= G.height || x >= G.width)
DATA(data) = 0;
else {
uint8_t ch = CHAR(data);
if (ch < ' ')
CHAR(data) = ch | 0x40;
else if (ch > 0x7e)
CHAR(data) = '?';
}
}
}
}
static void screen_char(char *data)
{
if (!BW) {
uint8_t attr_diff;
uint8_t attr = ATTR(data);
if (option_mask32 & FLAG(F)) {
attr >>= 1;
}
attr_diff = G.last_attr ^ attr;
if (attr_diff) {
// Attribute layout for VGA compatible text videobuffer:
// blinking text
// |red bkgd
// ||green bkgd
// |||blue bkgd
// vvvv
// 00000000 <- lsb bit on the right
// bold text / text 8th bit
// red text
// green text
// blue text
// TODO: apparently framebuffer-based console uses different layout
// (bug? attempt to get 8th text bit in better position?)
// red bkgd
// |green bkgd
// ||blue bkgd
// vvv
// 00000000 <- lsb bit on the right
// bold text
// red text
// green text
// blue text
// text 8th bit
// converting RGB color bit triad to BGR:
static const char color[8] = "04261537";
const uint8_t fg_mask = 0x07, bold_mask = 0x08;
const uint8_t bg_mask = 0x70, blink_mask = 0x80;
char *ptr;
ptr = G.attrbuf;
// (G.last_attr & ~attr) has 1 only where
// G.last_attr has 1 but attr has 0.
// Here we check whether we have transition
// bold->non-bold or blink->non-blink:
if (G.last_attr < 0 // initial value
|| ((G.last_attr & ~attr) & (bold_mask | blink_mask)) != 0
) {
*ptr++ = '0'; // "reset all attrs"
*ptr++ = ';';
// must set fg & bg, maybe need to set bold or blink:
attr_diff = attr | ~(bold_mask | blink_mask);
}
G.last_attr = attr;
if (attr_diff & bold_mask) {
*ptr++ = '1';
*ptr++ = ';';
}
if (attr_diff & blink_mask) {
*ptr++ = '5';
*ptr++ = ';';
}
if (attr_diff & fg_mask) {
*ptr++ = '3';
*ptr++ = color[attr & fg_mask];
*ptr++ = ';';
}
if (attr_diff & bg_mask) {
*ptr++ = '4';
*ptr++ = color[(attr & bg_mask) >> 4];
ptr++; // last attribute
}
if (ptr != G.attrbuf) {
ptr[-1] = 'm';
*ptr = '\0';
putcsi(G.attrbuf);
}
}
}
putchar(CHAR(data));
G.col++;
}
static void screen_dump(void)
{
int linefeed_cnt;
int line, col;
int linecnt = G.remote.lines - G.y;
char *data = G.data + G.current + G.first_line_offset;
linefeed_cnt = 0;
for (line = 0; line < linecnt && line < G.height; line++) {
int space_cnt = 0;
for (col = 0; col < G.remote.cols; col++, NEXT(data)) {
unsigned tty_col = col - G.x; // if will catch col < G.x too
if (tty_col >= G.width)
continue;
space_cnt++;
if (BW && CHAR(data) == ' ')
continue;
while (linefeed_cnt != 0) {
//bb_putchar('\r'); - tty driver does it for us
bb_putchar('\n');
linefeed_cnt--;
}
while (--space_cnt)
bb_putchar(' ');
screen_char(data);
}
linefeed_cnt++;
}
}
static void curmove(void)
{
unsigned cx = G.remote.cursor_x - G.x;
unsigned cy = G.remote.cursor_y - G.y;
int cursor = CURSOR_OFF;
if (cx < G.width && cy < G.height) {
gotoxy(cx, cy);
cursor = CURSOR_ON;
}
set_cursor(cursor);
}
static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
{
int fd = open(name, O_RDONLY);
if (fd != -1)
close(fd);
else if (errno == ENOENT)
mknod(name, S_IFCHR | 0660, dev);
}
static NOINLINE void start_shell_in_child(const char* tty_name)
{
int pid = xvfork();
if (pid == 0) {
struct termios termchild;
const char *shell = get_shell_name();
signal(SIGHUP, SIG_IGN);
// set tty as a controlling tty
setsid();
// make tty to be input, output, error
close(0);
xopen(tty_name, O_RDWR); // uses fd 0
xdup2(0, 1);
xdup2(0, 2);
ioctl(0, TIOCSCTTY, 1);
tcsetpgrp(0, getpid());
tcgetattr(0, &termchild);
termchild.c_lflag |= ECHO;
termchild.c_oflag |= ONLCR | XTABS;
termchild.c_iflag |= ICRNL;
termchild.c_iflag &= ~IXOFF;
tcsetattr_stdin_TCSANOW(&termchild);
execl(shell, shell, "-i", (char *) NULL);
bb_simple_perror_msg_and_die(shell);
}
}
int conspy_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int conspy_main(int argc UNUSED_PARAM, char **argv)
{
char tty_name[sizeof(DEV_TTY "NN")];
struct termios termbuf;
unsigned opts;
unsigned ttynum;
int poll_timeout_ms;
#if ENABLE_LONG_OPTS
static const char getopt_longopts[] ALIGN1 =
"viewonly\0" No_argument "v"
"createdevice\0" No_argument "c"
"neverquit\0" No_argument "Q"
"session\0" No_argument "s"
"nocolors\0" No_argument "n"
"dump\0" No_argument "d"
"follow\0" No_argument "f"
"framebuffer\0" No_argument "F"
;
applet_long_options = getopt_longopts;
#endif
#define keybuf bb_common_bufsiz1
setup_common_bufsiz();
INIT_G();
strcpy(G.vcsa_name, DEV_VCSA);
// numeric params
opts = getopt32(argv, "vcQsndfFx:+y:+", &G.x, &G.y);
argv += optind;
ttynum = 0;
if (argv[0]) {
ttynum = xatou_range(argv[0], 0, 63);
sprintf(G.vcsa_name + sizeof(DEV_VCSA)-1, "%u", ttynum);
}
sprintf(tty_name, "%s%u", DEV_TTY, ttynum);
if (opts & FLAG(c)) {
if ((opts & (FLAG(s)|FLAG(v))) != FLAG(v))
create_cdev_if_doesnt_exist(tty_name, makedev(4, ttynum));
create_cdev_if_doesnt_exist(G.vcsa_name, makedev(7, 128 + ttynum));
}
if ((opts & FLAG(s)) && ttynum) {
start_shell_in_child(tty_name);
}
screen_read_close();
if (opts & FLAG(d)) {
screen_dump();
bb_putchar('\n');
return 0;
}
bb_signals(BB_FATAL_SIGS, cleanup);
// All characters must be passed through to us unaltered
G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
tcgetattr(G.kbd_fd, &G.term_orig);
termbuf = G.term_orig;
termbuf.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
//termbuf.c_oflag &= ~(OPOST); - no, we still want \n -> \r\n
termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
termbuf.c_cc[VMIN] = 1;
termbuf.c_cc[VTIME] = 0;
tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
poll_timeout_ms = 250;
while (1) {
struct pollfd pfd;
int bytes_read;
int i, j;
char *data, *old;
// in the first loop G.width = G.height = 0: refresh
i = G.width;
j = G.height;
get_terminal_width_height(G.kbd_fd, &G.width, &G.height);
if (option_mask32 & FLAG(f)) {
int nx = G.remote.cursor_x - G.width + 1;
int ny = G.remote.cursor_y - G.height + 1;
if (G.remote.cursor_x < G.x) {
G.x = G.remote.cursor_x;
i = 0; // force refresh
}
if (nx > G.x) {
G.x = nx;
i = 0; // force refresh
}
if (G.remote.cursor_y < G.y) {
G.y = G.remote.cursor_y;
i = 0; // force refresh
}
if (ny > G.y) {
G.y = ny;
i = 0; // force refresh
}
}
// Scan console data and redraw our tty where needed
old = G.data + G.current;
G.current = G.size - G.current;
data = G.data + G.current;
screen_read_close();
if (i != G.width || j != G.height) {
clrscr();
screen_dump();
} else {
// For each remote line
old += G.first_line_offset;
data += G.first_line_offset;
for (i = G.y; i < G.remote.lines; i++) {
char *first = NULL; // first char which needs updating
char *last = last; // last char which needs updating
unsigned iy = i - G.y;
if (iy >= G.height)
break;
for (j = 0; j < G.remote.cols; j++, NEXT(old), NEXT(data)) {
unsigned jx = j - G.x; // if will catch j >= G.x too
if (jx < G.width && DATA(data) != DATA(old)) {
last = data;
if (!first) {
first = data;
gotoxy(jx, iy);
}
}
}
if (first) {
// Rewrite updated data on the local screen
for (; first <= last; NEXT(first))
screen_char(first);
}
}
}
curmove();
// Wait for local user keypresses
fflush_all();
pfd.fd = G.kbd_fd;
pfd.events = POLLIN;
bytes_read = 0;
switch (poll(&pfd, 1, poll_timeout_ms)) {
char *k;
case -1:
if (errno != EINTR)
goto abort;
break;
case 0:
if (++G.nokeys >= 4)
G.nokeys = G.escape_count = 0;
break;
default:
// Read the keys pressed
k = keybuf + G.key_count;
bytes_read = read(G.kbd_fd, k, COMMON_BUFSIZE - G.key_count);
if (bytes_read < 0)
goto abort;
// Do exit processing
if (!(option_mask32 & FLAG(Q))) {
for (i = 0; i < bytes_read; i++) {
if (k[i] != '\033')
G.escape_count = -1;
if (++G.escape_count >= 3)
cleanup(EXIT_SUCCESS);
}
}
}
poll_timeout_ms = 250;
if (option_mask32 & FLAG(v)) continue;
// Insert all keys pressed into the virtual console's input
// buffer. Don't do this if the virtual console is in scan
// code mode - giving ASCII characters to a program expecting
// scan codes will confuse it.
G.key_count += bytes_read;
if (G.escape_count == 0) {
int handle, result;
long kbd_mode;
handle = xopen(tty_name, O_WRONLY);
result = ioctl(handle, KDGKBMODE, &kbd_mode);
if (result >= 0) {
char *p = keybuf;
G.ioerror_count = 0;
if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE) {
G.key_count = 0; // scan code mode
}
for (; G.key_count != 0; p++, G.key_count--) {
result = ioctl(handle, TIOCSTI, p);
if (result < 0) {
memmove(keybuf, p, G.key_count);
break;
}
// If there is an application on console which reacts
// to keypresses, we need to make our first sleep
// shorter to quickly redraw whatever it printed there.
poll_timeout_ms = 20;
}
}
// We sometimes get spurious IO errors on the TTY
// as programs close and re-open it
else if (errno != EIO || ++G.ioerror_count > 4) {
if (ENABLE_FEATURE_CLEAN_UP)
close(handle);
goto abort;
}
// Close & re-open tty in case they have
// swapped virtual consoles
close(handle);
}
} /* while (1) */
abort:
cleanup(EXIT_FAILURE);
}