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/* 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.
*/
//config:config OPENVT
//config: bool "openvt (7.2 kb)"
//config: default y
//config: help
//config: This program is used to start a command on an unused
//config: virtual terminal.
//applet:IF_OPENVT(APPLET(openvt, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_OPENVT) += openvt.o
//usage:#define openvt_trivial_usage
//usage: "[-c N] [-sw] [PROG ARGS]"
//usage:#define openvt_full_usage "\n\n"
//usage: "Start PROG on a new virtual terminal\n"
//usage: "\n -c N Use specified VT"
//usage: "\n -s Switch to the VT"
/* //usage: "\n -l Run PROG as login shell (by prepending '-')" */
//usage: "\n -w Wait for PROG to exit"
//usage:
//usage:#define openvt_example_usage
//usage: "openvt 2 /bin/ash\n"
#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_simple_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_simple_perror_msg_and_die("can't find open VT");
// Not really needed, grep for DAEMON_CLOSE_EXTRA_FDS
// 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_daemon_helper(DAEMON_CLOSE_EXTRA_FDS);
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] = (char *) get_shell_name();
/*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;
}
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