mirror of
https://github.com/sheumann/hush.git
synced 2024-08-18 21:29:23 +00:00
This change retains "or later" state! No licensing _changes_ here, only form is adjusted (article, space between "GPL" and "v2" and so on). Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
148 lines
4.4 KiB
C
148 lines
4.4 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/*
|
|
* Copyright (c) 2007 Denys Vlasenko <vda.linux@googlemail.com>
|
|
*
|
|
* Licensed under GPLv2, see file LICENSE in this source tree.
|
|
*/
|
|
#include "libbb.h"
|
|
|
|
//applet:IF_CTTYHACK(APPLET(cttyhack, _BB_DIR_BIN, _BB_SUID_DROP))
|
|
|
|
//kbuild:lib-$(CONFIG_CTTYHACK) += cttyhack.o
|
|
|
|
//config:config CTTYHACK
|
|
//config: bool "cttyhack"
|
|
//config: default y
|
|
//config: help
|
|
//config: One common problem reported on the mailing list is "can't access tty;
|
|
//config: job control turned off" error message which typically appears when
|
|
//config: one tries to use shell with stdin/stdout opened to /dev/console.
|
|
//config: This device is special - it cannot be a controlling tty.
|
|
//config:
|
|
//config: Proper solution is to use correct device instead of /dev/console.
|
|
//config:
|
|
//config: cttyhack provides "quick and dirty" solution to this problem.
|
|
//config: It analyzes stdin with various ioctls, trying to determine whether
|
|
//config: it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
|
|
//config: If it detects one, it closes stdin/out/err and reopens that device.
|
|
//config: Then it executes given program. Opening the device will make
|
|
//config: that device a controlling tty. This may require cttyhack
|
|
//config: to be a session leader.
|
|
//config:
|
|
//config: Example for /etc/inittab (for busybox init):
|
|
//config:
|
|
//config: ::respawn:/bin/cttyhack /bin/sh
|
|
//config:
|
|
//config: Starting an interactive shell from boot shell script:
|
|
//config:
|
|
//config: setsid cttyhack sh
|
|
//config:
|
|
//config: Giving controlling tty to shell running with PID 1:
|
|
//config:
|
|
//config: # exec cttyhack sh
|
|
//config:
|
|
//config: Without cttyhack, you need to know exact tty name,
|
|
//config: and do something like this:
|
|
//config:
|
|
//config: # exec setsid sh -c 'exec sh </dev/tty1 >/dev/tty1 2>&1'
|
|
//config:
|
|
|
|
//usage:#define cttyhack_trivial_usage
|
|
//usage: "PROG ARGS"
|
|
//usage:#define cttyhack_full_usage "\n\n"
|
|
//usage: "Give PROG a controlling tty if possible."
|
|
//usage: "\nExample for /etc/inittab (for busybox init):"
|
|
//usage: "\n ::respawn:/bin/cttyhack /bin/sh"
|
|
//usage: "\nGiving controlling tty to shell running with PID 1:"
|
|
//usage: "\n $ exec cttyhack sh"
|
|
//usage: "\nStarting interactive shell from boot shell script:"
|
|
//usage: "\n setsid cttyhack sh"
|
|
|
|
#if !defined(__linux__) && !defined(TIOCGSERIAL) && !ENABLE_WERROR
|
|
# warning cttyhack will not be able to detect a controlling tty on this system
|
|
#endif
|
|
|
|
/* From <linux/vt.h> */
|
|
struct vt_stat {
|
|
unsigned short v_active; /* active vt */
|
|
unsigned short v_signal; /* signal to send */
|
|
unsigned short v_state; /* vt bitmask */
|
|
};
|
|
enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */
|
|
|
|
/* From <linux/serial.h> */
|
|
struct serial_struct {
|
|
int type;
|
|
int line;
|
|
unsigned int port;
|
|
int irq;
|
|
int flags;
|
|
int xmit_fifo_size;
|
|
int custom_divisor;
|
|
int baud_base;
|
|
unsigned short close_delay;
|
|
char io_type;
|
|
char reserved_char[1];
|
|
int hub6;
|
|
unsigned short closing_wait; /* time to wait before closing */
|
|
unsigned short closing_wait2; /* no longer used... */
|
|
unsigned char *iomem_base;
|
|
unsigned short iomem_reg_shift;
|
|
unsigned int port_high;
|
|
unsigned long iomap_base; /* cookie passed into ioremap */
|
|
int reserved[1];
|
|
};
|
|
|
|
int cttyhack_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
|
int cttyhack_main(int argc UNUSED_PARAM, char **argv)
|
|
{
|
|
int fd;
|
|
char console[sizeof(int)*3 + 16];
|
|
union {
|
|
struct vt_stat vt;
|
|
struct serial_struct sr;
|
|
char paranoia[sizeof(struct serial_struct) * 3];
|
|
} u;
|
|
|
|
if (!*++argv) {
|
|
bb_show_usage();
|
|
}
|
|
|
|
strcpy(console, "/dev/tty");
|
|
fd = open(console, O_RDWR);
|
|
if (fd >= 0) {
|
|
/* We already have ctty, nothing to do */
|
|
close(fd);
|
|
} else {
|
|
/* We don't have ctty (or don't have "/dev/tty" node...) */
|
|
if (0) {}
|
|
#ifdef TIOCGSERIAL
|
|
else if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
|
|
/* this is a serial console */
|
|
sprintf(console + 8, "S%d", u.sr.line);
|
|
}
|
|
#endif
|
|
#ifdef __linux__
|
|
else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
|
|
/* this is linux virtual tty */
|
|
sprintf(console + 8, "S%d" + 1, u.vt.v_active);
|
|
}
|
|
#endif
|
|
if (console[8]) {
|
|
fd = xopen(console, O_RDWR);
|
|
//bb_error_msg("switching to '%s'", console);
|
|
dup2(fd, 0);
|
|
dup2(fd, 1);
|
|
dup2(fd, 2);
|
|
while (fd > 2)
|
|
close(fd--);
|
|
/* Some other session may have it as ctty,
|
|
* steal it from them:
|
|
*/
|
|
ioctl(0, TIOCSCTTY, 1);
|
|
}
|
|
}
|
|
|
|
BB_EXECVP_or_die(argv);
|
|
}
|