*
* 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: bool "cttyhack (2.5 kb)"
//config: default y
//config: help
-//config: One common problem reported on the mailing list is the "can't
-//config: access tty; job control turned off" error message, which typically
-//config: appears when one tries to use a shell with stdin/stdout on
-//config: /dev/console.
-//config: This device is special - it cannot be a controlling tty.
+//config: One common problem reported on the mailing list is the "can't
+//config: access tty; job control turned off" error message, which typically
+//config: appears when one tries to use a shell with stdin/stdout on
+//config: /dev/console.
+//config: This device is special - it cannot be a controlling tty.
//config:
-//config: The proper solution is to use the correct device instead of
-//config: /dev/console.
+//config: The proper solution is to use the correct device instead of
+//config: /dev/console.
//config:
-//config: cttyhack provides a "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: On Linux it also checks sysfs for a pointer to the active console.
-//config: If cttyhack is able to find the real console device, it closes
-//config: stdin/out/err and reopens that device.
-//config: Then it executes the given program. Opening the device will make
-//config: that device a controlling tty. This may require cttyhack
-//config: to be a session leader.
+//config: cttyhack provides a "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: On Linux it also checks sysfs for a pointer to the active console.
+//config: If cttyhack is able to find the real console device, it closes
+//config: stdin/out/err and reopens that device.
+//config: Then it executes the 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: Example for /etc/inittab (for busybox init):
//config:
-//config: ::respawn:/bin/cttyhack /bin/sh
+//config: ::respawn:/bin/cttyhack /bin/sh
//config:
-//config: Starting an interactive shell from boot shell script:
+//config: Starting an interactive shell from boot shell script:
//config:
-//config: setsid cttyhack sh
+//config: setsid cttyhack sh
//config:
-//config: Giving controlling tty to shell running with PID 1:
+//config: Giving controlling tty to shell running with PID 1:
//config:
-//config: # exec cttyhack sh
+//config: # exec cttyhack sh
//config:
-//config: Without cttyhack, you need to know exact tty name,
-//config: and do something like this:
+//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: # exec setsid sh -c 'exec sh </dev/tty1 >/dev/tty1 2>&1'
//config:
-//config: Starting getty on a controlling tty from a shell script:
+//config: Starting getty on a controlling tty from a shell script:
//config:
-//config: # getty 115200 $(cttyhack)
+//config: # getty 115200 $(cttyhack)
+
+//applet:IF_CTTYHACK(APPLET_NOEXEC(cttyhack, cttyhack, BB_DIR_BIN, BB_SUID_DROP, cttyhack))
+
+//kbuild:lib-$(CONFIG_CTTYHACK) += cttyhack.o
//usage:#define cttyhack_trivial_usage
//usage: "[PROG ARGS]"
//usage: "\nStarting interactive shell from boot shell script:"
//usage: "\n setsid cttyhack sh"
+#include "libbb.h"
+
#if !defined(__linux__) && !defined(TIOCGSERIAL) && !ENABLE_WERROR
# warning cttyhack will not be able to detect a controlling tty on this system
#endif
/* We don't have ctty (or don't have "/dev/tty" node...) */
do {
#ifdef __linux__
- int s;
+ /* Note that this method does not use _stdin_.
+ * Thus, "cttyhack </dev/something" can't be used.
+ * However, this method is more reliable than
+ * TIOCGSERIAL check, which assumes that all
+ * serial lines follow /dev/ttySn convention -
+ * which is not always the case.
+ * Therefore, we use this method first:
+ */
+ int s = open_read_close("/sys/class/tty/console/active",
+ console + 5, sizeof(console) - 5);
+ if (s > 0) {
+ char *last;
+ /* Found active console via sysfs (Linux 2.6.38+).
+ * It looks like "[tty0 ]ttyS0\n" so zap the newline:
+ */
+ console[4 + s] = '\0';
+ /* If there are multiple consoles,
+ * take the last one:
+ */
+ last = strrchr(console + 5, ' ');
+ if (last)
+ overlapping_strcpy(console + 5, last + 1);
+ break;
+ }
+
if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
/* this is linux virtual tty */
sprintf(console + 8, "S%u" + 1, (int)u.vt.v_active);
sprintf(console + 8, "S%u", (int)u.sr.line);
break;
}
-#endif
-#ifdef __linux__
- /* Note that this method is not related to _stdin_ */
- s = open_read_close("/sys/class/tty/console/active",
- console + 5, sizeof(console) - 5);
- if (s > 0) {
- /* found active console via sysfs (Linux 2.6.38+)
- * sysfs string looks like "ttyS0\n" so zap the newline:
- */
- console[4 + s] = '\0';
- break;
- }
#endif
/* nope, could not find it */
console[0] = '\0';
projects / oweals / busybox.git / blobdiff