source: MondoRescue/branches/2.2.9/mindi-busybox/console-tools/openvt.c@ 2725

/* vi: set sw=4 ts=4: */
/*
 *  openvt.c - open a vt to run a command.
 *
 *  busyboxed by Quy Tonthat <quy@signal3.com>
 *  hacked by Tito <farmatito@tiscali.it>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include <linux/vt.h>
#include "libbb.h"

/* "Standard" openvt's man page (we do not support all of this):

openvt [-c NUM] [-fsulv] [--] [command [args]]

Find the first available VT, and run command on it. Stdio is directed
to that VT. If no command is specified then $SHELL is used.

-c NUM
    Use the given VT number, not the first free one.
-f
    Force opening a VT: don't try to check if VT is already in use.
-s
    Switch to the new VT when starting the command.
    The VT of the new command will be made the new current VT.
-u
    Figure out the owner of the current VT, and run login as that user.
    Suitable to be called by init. Shouldn't be used with -c or -l.
-l
    Make the command a login shell: a "-" is prepended to the argv[0]
    when command is executed.
-v
    Verbose.
-w
    Wait for command to complete. If -w and -s are used together,
    switch back to the controlling terminal when the command completes.

bbox:
-u: not implemented
-f: always in effect
-l: not implemented, ignored
-v: ignored
-ws: does NOT switch back
*/

/* Helper: does this fd understand VT_xxx? */
static int not_vt_fd(int fd)
{
    struct vt_stat vtstat;
    return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */
}

/* Helper: get a fd suitable for VT_xxx */
static int get_vt_fd(void)
{
    int fd;

    /* Do we, by chance, already have it? */
    for (fd = 0; fd < 3; fd++)
        if (!not_vt_fd(fd))
            return fd;
    fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK);
    if (fd >= 0 && !not_vt_fd(fd))
        return fd;
    bb_error_msg_and_die("can't find open VT");
}

static int find_free_vtno(void)
{
    int vtno;
    int fd = get_vt_fd();

    errno = 0;
    /*xfunc_error_retval = 3; - do we need compat? */
    if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0)
        bb_perror_msg_and_die("can't find open VT");
// Not really needed, grep for DAEMON_ONLY_SANITIZE
//  if (fd > 2)
//      close(fd);
    return vtno;
}

/* vfork scares gcc, it generates bigger code.
 * Keep it away from main program.
 * TODO: move to libbb; or adapt existing libbb's spawn().
 */
static NOINLINE void vfork_child(char **argv)
{
    if (vfork() == 0) {
        /* CHILD */
        /* Try to make this VT our controlling tty */
        setsid(); /* lose old ctty */
        ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */);
        //bb_error_msg("our sid %d", getsid(0));
        //bb_error_msg("our pgrp %d", getpgrp());
        //bb_error_msg("VT's sid %d", tcgetsid(0));
        //bb_error_msg("VT's pgrp %d", tcgetpgrp(0));
        BB_EXECVP_or_die(argv);
    }
}

int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int openvt_main(int argc UNUSED_PARAM, char **argv)
{
    char vtname[sizeof(VC_FORMAT) + sizeof(int)*3];
    struct vt_stat vtstat;
    char *str_c;
    int vtno;
    int flags;
    enum {
        OPT_c = (1 << 0),
        OPT_w = (1 << 1),
        OPT_s = (1 << 2),
        OPT_l = (1 << 3),
        OPT_f = (1 << 4),
        OPT_v = (1 << 5),
    };

    /* "+" - stop on first non-option */
    flags = getopt32(argv, "+c:wslfv", &str_c);
    argv += optind;

    if (flags & OPT_c) {
        /* Check for illegal vt number: < 1 or > 63 */
        vtno = xatou_range(str_c, 1, 63);
    } else {
        vtno = find_free_vtno();
    }

    /* Grab new VT */
    sprintf(vtname, VC_FORMAT, vtno);
    /* (Try to) clean up stray open fds above fd 2 */
    bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL);
    close(STDIN_FILENO);
    /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */
    xopen(vtname, O_RDWR);
    xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat);

    if (flags & OPT_s) {
        console_make_active(STDIN_FILENO, vtno);
    }

    if (!argv[0]) {
        argv--;
        argv[0] = getenv("SHELL");
        if (!argv[0])
            argv[0] = (char *) DEFAULT_SHELL;
        /*argv[1] = NULL; - already is */
    }

    xdup2(STDIN_FILENO, STDOUT_FILENO);
    xdup2(STDIN_FILENO, STDERR_FILENO);

#ifdef BLOAT
    {
    /* Handle -l (login shell) option */
    const char *prog = argv[0];
    if (flags & OPT_l)
        argv[0] = xasprintf("-%s", argv[0]);
    }
#endif

    vfork_child(argv);
    if (flags & OPT_w) {
        /* We have only one child, wait for it */
        safe_waitpid(-1, NULL, 0); /* loops on EINTR */
        if (flags & OPT_s) {
            console_make_active(STDIN_FILENO, vtstat.v_active);
            // Compat: even with -c N (try to) disallocate:
            // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5
            // openvt: could not deallocate console 9
            xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno);
        }
    }
    return EXIT_SUCCESS;
}