conspy: new applet

Signed-off-by: Pascal Bellard <pascal.bellard@ads-lu.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 472 insertions, 0 deletions

diff --git a/miscutils/conspy.c b/miscutils/conspy.c
new file mode 100644
index 000000000..7ba7959a2
--- /dev/null
+++ b/miscutils/conspy.c
@@ -0,0 +1,472 @@
+/* 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 tarball for details.
+ *
+ * example :    conspy num              shared access to console num
+ * or           conspy -d num           screenshot of console num
+ * 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
+
+//config:config CONSPY
+//config:       bool "conspy"
+//config:       default n
+//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 -d num   screenshot of console num
+//config:         or        conspy -cs num  poor man's GNU screen like
+
+//usage:#define conspy_trivial_usage
+//usage:     "[-vcsndf] [-x ROW] [-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:     "\nOptions:"
+//usage:     "\n        -v      Don't send keystrokes to the console"
+//usage:     "\n        -c      Create missing devices in /dev"
+//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        -x ROW  Starting row"
+//usage:     "\n        -y LINE Starting line"
+
+#include "libbb.h"
+#include <sys/kd.h>
+
+struct screen_info {
+        unsigned char lines, rows, cursor_x, cursor_y;
+};
+
+#define CHAR(x) ((x)[0])
+#define ATTR(x) ((x)[1])
+#define NEXT(x) ((x)+=2)
+#define DATA(x) (* (short *) (x))
+
+struct globals {
+        char* data;
+        int size;
+        int x, y;
+        int kbd_fd;
+        unsigned width;
+        unsigned height;
+        char mask;
+        char last_attr;
+        struct screen_info info;
+        struct termios term_orig;
+};
+
+#define G (*ptr_to_globals)
+#define INIT_G() do { \
+        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
+} while (0)
+
+static void screen_read_close(int fd, char *data)
+{
+        unsigned i, j;
+
+        xread(fd, data, G.size);
+        G.last_attr = 0;
+        for (i = 0; i < G.info.lines; i++) {
+                for (j = 0; j < G.info.rows; 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 (CHAR(data) < ' ')
+                                CHAR(data) = ' ';
+                        if (y >= G.height || x >= G.width)
+                                DATA(data) = 0;
+                }
+        }
+        close(fd);
+}
+
+static void screen_char(char *data)
+{
+        if (((G.last_attr - ATTR(data)) & G.mask) != 0) {
+                //                            BLGCRMOW
+                static const char color[8] = "04261537";
+
+                printf("\033[%c;4%c;3%cm",
+                        (ATTR(data) & 8) ? '1'  // bold
+                                         : '0', // defaults
+                        color[(ATTR(data) >> 4) & 7], color[ATTR(data) & 7]);
+                G.last_attr = ATTR(data);
+        }
+        bb_putchar(CHAR(data));
+}
+
+#define clrscr()  printf("\033[1;1H" "\033[0J")
+#define curoff()  printf("\033[?25l")
+
+static void curon(void)
+{
+        printf("\033[?25h");
+}
+
+static void gotoxy(int row, int line)
+{
+        printf("\033[%u;%uH", line + 1, row + 1);
+}
+
+static void screen_dump(char *data)
+{
+        int space, linefeed, line, row;
+        int linecnt = G.info.lines - G.y;
+
+        data += 2 * G.y * G.info.rows;
+        for (linefeed = line = 0; line < linecnt && line < G.height; line++) {
+                for (space = row = 0; row < G.info.rows; row++, NEXT(data)) {
+                        unsigned tty_row = row - G.x; // if will catch row < G.x too
+
+                        if (tty_row >= G.width)
+                                continue;
+                        space++;
+                        if (((G.last_attr - ATTR(data)) & G.mask) && CHAR(data) == ' ')
+                                continue;
+                        while (linefeed != 0) {
+                                bb_putchar('\r');
+                                bb_putchar('\n');
+                                linefeed--;
+                        }
+                        while (--space)
+                                bb_putchar(' ');
+                        screen_char(data);
+                }
+                linefeed++;
+        }
+}
+
+static void curmove(void)
+{
+        unsigned cx = G.info.cursor_x - G.x;
+        unsigned cy = G.info.cursor_y - G.y;
+
+        if (cx >= G.width || cy >= G.height) {
+                curoff();
+        } else {
+                curon();
+                gotoxy(cx, cy);
+        }
+        fflush_all();
+}
+
+static void cleanup(int code)
+{
+        curon();
+        fflush_all();
+        tcsetattr(G.kbd_fd, TCSANOW, &G.term_orig);
+        if (ENABLE_FEATURE_CLEAN_UP) {
+                free(ptr_to_globals);
+                close(G.kbd_fd);
+        }
+        // Reset attributes
+        if (G.mask != 0)
+                printf("\033[0m");
+        bb_putchar('\n');
+        if (code > 1)
+                kill_myself_with_sig(code); // does not return
+        exit(code);
+}
+
+static void get_initial_data(const char* vcsa_name)
+{
+        int size;
+        int fd = xopen(vcsa_name, O_RDONLY);
+        xread(fd, &G.info, 4);
+        G.size = size = G.info.rows * G.info.lines * 2;
+        G.width = G.height = UINT_MAX;
+        G.data = xzalloc(2 * size);
+        screen_read_close(fd, G.data);
+}
+
+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 = vfork();
+        if (pid < 0) {
+                bb_perror_msg_and_die("vfork");
+        }
+        if (pid == 0) {
+                struct termios termchild;
+                char *shell = getenv("SHELL");
+
+                if (!shell)
+                        shell = (char *) DEFAULT_SHELL;
+                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);
+        }
+}
+
+enum {
+        FLAG_v,  // view only
+        FLAG_c,  // create device if need
+        FLAG_s,  // session
+        FLAG_n,  // no colors
+        FLAG_d,  // dump screen
+        FLAG_f,  // follow cursor
+};
+#define FLAG(x) (1 << FLAG_##x)
+
+int conspy_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int conspy_main(int argc UNUSED_PARAM, char **argv)
+{
+        char *buffer[2];
+        char vcsa_name[sizeof("/dev/vcsa") + 2];
+        char tty_name[sizeof("/dev/tty") + 2];
+#define keybuf bb_common_bufsiz1
+        struct termios termbuf;
+        unsigned opts;
+        unsigned ttynum;
+        int poll_timeout_ms;
+        int current;
+        int ioerror_count;
+        int key_count;
+        int escape_count;
+        int nokeys;
+#if ENABLE_LONG_OPTS
+        static const char getopt_longopts[] ALIGN1 =
+                "viewonly\0"     No_argument "v"
+                "createdevice\0" No_argument "c"
+                "session\0"      No_argument "s"
+                "nocolors\0"     No_argument "n"
+                "dump\0"         No_argument "d"
+                "follow\0"       No_argument "f"
+                ;
+
+        applet_long_options = getopt_longopts;
+#endif
+        INIT_G();
+        strcpy(vcsa_name, "/dev/vcsa");
+
+        opt_complementary = "x+:y+"; // numeric params
+        opts = getopt32(argv, "vcsndfx:y:", &G.x, &G.y);
+        argv += optind;
+        ttynum = 0;
+        if (argv[0]) {
+                ttynum = xatou_range(argv[0], 0, 63);
+                sprintf(vcsa_name + sizeof("/dev/vcsa")-1, "%u", ttynum);
+        }
+        sprintf(tty_name, "%s%u", "/dev/tty", ttynum);
+        if (!(opts & FLAG(n)))
+                G.mask = 0xff;
+        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(vcsa_name, makedev(7, 128 + ttynum));
+        }
+        if ((opts & FLAG(s)) && ttynum) {
+                start_shell_in_child(tty_name);
+        }
+
+        get_initial_data(vcsa_name);
+        G.kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
+        if (opts & FLAG(d)) {
+                screen_dump(G.data);
+                bb_putchar('\n');
+                if (ENABLE_FEATURE_CLEAN_UP) {
+                        free(ptr_to_globals);
+                        close(G.kbd_fd);
+                }
+                return 0;
+        }
+
+        bb_signals(BB_FATAL_SIGS, cleanup);
+        // All characters must be passed through to us unaltered
+        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);
+        termbuf.c_lflag &= ~(ISIG|ICANON|ECHO);
+        termbuf.c_cc[VMIN] = 1;
+        termbuf.c_cc[VTIME] = 0;
+        tcsetattr(G.kbd_fd, TCSANOW, &termbuf);
+        buffer[0] = G.data;
+        buffer[1] = G.data + G.size;
+        poll_timeout_ms = 250;
+        ioerror_count = key_count = escape_count = nokeys = current = 0;
+        while (1) {
+                struct pollfd pfd;
+                int vcsa_handle;
+                int bytes_read;
+                int i, j;
+                int next = 1 - current;
+                char *data = buffer[next];
+                char *old  = buffer[current];
+
+                // Close & re-open vcsa in case they have
+                // swapped virtual consoles
+                vcsa_handle = xopen(vcsa_name, O_RDONLY);
+                xread(vcsa_handle, &G.info, 4);
+                if (G.size != (G.info.rows * G.info.lines * 2)) {
+                        cleanup(1);
+                }
+                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.info.cursor_x - G.width + 1;
+                        int ny = G.info.cursor_y - G.height + 1;
+
+                        if (G.info.cursor_x < G.x) {
+                                G.x = G.info.cursor_x;
+                                i = 0;  // force refresh
+                        }
+                        if (nx > G.x) {
+                                G.x = nx;
+                                i = 0;  // force refresh
+                        }
+                        if (G.info.cursor_y < G.y) {
+                                G.y = G.info.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
+                screen_read_close(vcsa_handle, data);
+                if (i != G.width || j != G.height) {
+                        clrscr();
+                        screen_dump(data);
+                }
+                else for (i = 0; i < G.info.lines; i++) {
+                        char *last = last;
+                        char *first = NULL;
+                        int iy = i - G.y;
+
+                        if (iy >= (int) G.height)
+                                break;
+                        for (j = 0; j < G.info.rows; j++) {
+                                last = data;
+                                if (DATA(data) != DATA(old) && iy >= 0) {
+                                        unsigned jx = j - G.x;
+
+                                        last = NULL;
+                                        if (first == NULL && jx < G.width) {
+                                                first = data;
+                                                gotoxy(jx, iy);
+                                        }
+                                }
+                                NEXT(old);
+                                NEXT(data);
+                        }
+                        if (first == NULL)
+                                continue;
+                        if (last == NULL)
+                                last = data;
+
+                        // Write the data to the screen
+                        for (; first < last; NEXT(first))
+                                screen_char(first);
+                }
+                current = next;
+                curmove();
+
+                // Wait for local user keypresses
+                pfd.fd = G.kbd_fd;
+                pfd.events = POLLIN;
+                bytes_read = 0;
+                switch (poll(&pfd, 1, poll_timeout_ms)) {
+                case -1:
+                        if (errno != EINTR)
+                                cleanup(1);
+                        break;
+                case 0:
+                        if (++nokeys >= 4)
+                                nokeys = escape_count = 0;
+                        break;
+                default:
+                        // Read the keys pressed
+                        bytes_read = read(G.kbd_fd, keybuf + key_count,
+                                        sizeof(keybuf) - key_count);
+                        if (bytes_read < 0)
+                                cleanup(1);
+
+                        // Do exit processing
+                        for (i = 0; i < bytes_read; i++) {
+                                if (keybuf[key_count + i] != '\033')
+                                        escape_count = 0;
+                                else if (++escape_count >= 3)
+                                        cleanup(0);
+                        }
+                }
+                poll_timeout_ms = 250;
+
+                // 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.
+                if (!(option_mask32 & FLAG(v)) && escape_count == 0) {
+                        int handle, result;
+                        long kbd_mode;
+
+                        key_count += bytes_read;
+                        handle = xopen(tty_name, O_WRONLY);
+                        result = ioctl(handle, KDGKBMODE, &kbd_mode);
+                        if (result == -1)
+                                /* nothing */;
+                        else if (kbd_mode != K_XLATE && kbd_mode != K_UNICODE)
+                                key_count = 0; // scan code mode
+                        else {
+                                for (i = 0; i < key_count && result != -1; i++)
+                                        result = ioctl(handle, TIOCSTI, keybuf + i);
+                                key_count -= i;
+                                if (key_count)
+                                        memmove(keybuf, keybuf + i, key_count);
+                                // 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;
+                        }
+                        // Close & re-open tty in case they have
+                        // swapped virtual consoles
+                        close(handle);
+
+                        // We sometimes get spurious IO errors on the TTY
+                        // as programs close and re-open it
+                        if (result != -1)
+                                ioerror_count = 0;
+                        else if (errno != EIO || ++ioerror_count > 4)
+                                cleanup(1);
+                }
+        }
+}