123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147 |
- /* 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);
- }
|