Changeset 2725 in MondoRescue for branches/2.2.9/mindi-busybox/shell/cttyhack.c

Timestamp:

Feb 25, 2011, 9:26:54 PM (13 years ago)

Author:

Bruno Cornec

Message:

• Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3

File:

• branches/2.2.9/mindi-busybox/shell/cttyhack.c (modified) (4 diffs)

branches/2.2.9/mindi-busybox/shell/cttyhack.c

@@ -1 @@
-/* This code is adapted from busybox project
+/* vi: set sw=4 ts=4: */
+/*
+ * Copyright (c) 2007 Denys Vlasenko <vda.linux@googlemail.com>
  *
- * Licensed under GPLv2
+ * 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 */
+    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 */
+enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */
 
 /* From <linux/serial.h> */
@@ -27 +85 @@
     char    reserved_char[1];
     int hub6;
-    unsigned short  closing_wait; /* time to wait before closing */
-    unsigned short  closing_wait2; /* no longer used... */
+    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;
@@ -36 +94 @@
 };
 
-int cttyhack_main(int argc, char **argv) ATTRIBUTE_NORETURN;
-int cttyhack_main(int argc, char **argv)
+int cttyhack_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int cttyhack_main(int argc UNUSED_PARAM, char **argv)
 {
     int fd;
@@ -52 +110 @@
 
     strcpy(console, "/dev/tty");
-    if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
-        /* this is a serial console */
-        sprintf(console + 8, "S%d", u.sr.line);
-    } else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
-        /* this is linux virtual tty */
-        sprintf(console + 8, "S%d" + 1, u.vt.v_active);
+    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);
+        }
     }
 
-    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--);
-    }
-
-    execvp(argv[0], argv);
-    bb_perror_msg_and_die("cannot exec '%s'", argv[0]);
+    BB_EXECVP_or_die(argv);
 }