tar: support -T - and -X -
[oweals/busybox.git] / init / init.c
index d8bf15894539cda3a914d58bbc6382729ec7e46d..586e34a18eb448d4b6cef4789e7614ee88138ce6 100644 (file)
@@ -6,9 +6,108 @@
  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  * Adjusted by so many folks, it's impossible to keep track.
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
+//applet:IF_INIT(APPLET(init, BB_DIR_SBIN, BB_SUID_DROP))
+//applet:IF_FEATURE_INITRD(APPLET_ODDNAME(linuxrc, init, BB_DIR_ROOT, BB_SUID_DROP, linuxrc))
+
+//kbuild:lib-$(CONFIG_INIT) += init.o
+
+//config:config INIT
+//config:      bool "init"
+//config:      default y
+//config:      select FEATURE_SYSLOG
+//config:      help
+//config:        init is the first program run when the system boots.
+//config:
+//config:config FEATURE_USE_INITTAB
+//config:      bool "Support reading an inittab file"
+//config:      default y
+//config:      depends on INIT
+//config:      help
+//config:        Allow init to read an inittab file when the system boot.
+//config:
+//config:config FEATURE_KILL_REMOVED
+//config:      bool "Support killing processes that have been removed from inittab"
+//config:      default n
+//config:      depends on FEATURE_USE_INITTAB
+//config:      help
+//config:        When respawn entries are removed from inittab and a SIGHUP is
+//config:        sent to init, this option will make init kill the processes
+//config:        that have been removed.
+//config:
+//config:config FEATURE_KILL_DELAY
+//config:      int "How long to wait between TERM and KILL (0 - send TERM only)" if FEATURE_KILL_REMOVED
+//config:      range 0 1024
+//config:      default 0
+//config:      depends on FEATURE_KILL_REMOVED
+//config:      help
+//config:        With nonzero setting, init sends TERM, forks, child waits N
+//config:        seconds, sends KILL and exits. Setting it too high is unwise
+//config:        (child will hang around for too long and could actually kill
+//config:        the wrong process!)
+//config:
+//config:config FEATURE_INIT_SCTTY
+//config:      bool "Run commands with leading dash with controlling tty"
+//config:      default y
+//config:      depends on INIT
+//config:      help
+//config:        If this option is enabled, init will try to give a controlling
+//config:        tty to any command which has leading hyphen (often it's "-/bin/sh").
+//config:        More precisely, init will do "ioctl(STDIN_FILENO, TIOCSCTTY, 0)".
+//config:        If device attached to STDIN_FILENO can be a ctty but is not yet
+//config:        a ctty for other session, it will become this process' ctty.
+//config:        This is not the traditional init behavour, but is often what you want
+//config:        in an embedded system where the console is only accessed during
+//config:        development or for maintenance.
+//config:        NB: using cttyhack applet may work better.
+//config:
+//config:config FEATURE_INIT_SYSLOG
+//config:      bool "Enable init to write to syslog"
+//config:      default y
+//config:      depends on INIT
+//config:
+//config:config FEATURE_EXTRA_QUIET
+//config:      bool "Be _extra_ quiet on boot"
+//config:      default y
+//config:      depends on INIT
+//config:      help
+//config:        Prevent init from logging some messages to the console during boot.
+//config:
+//config:config FEATURE_INIT_COREDUMPS
+//config:      bool "Support dumping core for child processes (debugging only)"
+//config:      default y
+//config:      depends on INIT
+//config:      help
+//config:        If this option is enabled and the file /.init_enable_core
+//config:        exists, then init will call setrlimit() to allow unlimited
+//config:        core file sizes. If this option is disabled, processes
+//config:        will not generate any core files.
+//config:
+//config:config FEATURE_INITRD
+//config:      bool "Support running init from within an initrd (not initramfs)"
+//config:      default y
+//config:      depends on INIT
+//config:      help
+//config:        Legacy support for running init under the old-style initrd. Allows
+//config:        the name linuxrc to act as init, and it doesn't assume init is PID 1.
+//config:
+//config:        This does not apply to initramfs, which runs /init as PID 1 and
+//config:        requires no special support.
+//config:
+//config:config INIT_TERMINAL_TYPE
+//config:      string "Initial terminal type"
+//config:      default "linux"
+//config:      depends on INIT
+//config:      help
+//config:        This is the initial value set by init for the TERM environment
+//config:        variable. This variable is used by programs which make use of
+//config:        extended terminal capabilities.
+//config:
+//config:        Note that on Linux, init attempts to detect serial terminal and
+//config:        sets TERM to "vt102" if one is found.
+
 #include "libbb.h"
 #include <syslog.h>
 #include <paths.h>
 #ifdef __linux__
 #include <linux/vt.h>
 #endif
-#if ENABLE_FEATURE_UTMP
-# include <utmp.h> /* DEAD_PROCESS */
-#endif
 #include "reboot.h" /* reboot() constants */
 
 /* Used only for sanitizing purposes in set_sane_term() below. On systems where
@@ -205,7 +301,7 @@ static void console_init(void)
        } else
 #endif
        if (!s)
-               putenv((char*)"TERM=linux");
+               putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE);
 }
 
 /* Set terminal settings to reasonable defaults.
@@ -232,7 +328,11 @@ static void set_sane_term(void)
 #endif
 
        /* Make it be sane */
-       tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
+#ifndef CRTSCTS
+# define CRTSCTS 0
+#endif
+       /* added CRTSCTS to fix Debian bug 528560 */
+       tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD | CRTSCTS;
        tty.c_cflag |= CREAD | HUPCL | CLOCAL;
 
        /* input modes */
@@ -242,8 +342,7 @@ static void set_sane_term(void)
        tty.c_oflag = OPOST | ONLCR;
 
        /* local modes */
-       tty.c_lflag =
-               ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
+       tty.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
 
        tcsetattr_stdin_TCSANOW(&tty);
 }
@@ -299,20 +398,22 @@ static void init_exec(const char *command)
        char buf[COMMAND_SIZE + 6];  /* COMMAND_SIZE+strlen("exec ")+1 */
        int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
 
+       command += dash;
+
        /* See if any special /bin/sh requiring characters are present */
        if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
-               strcpy(buf, "exec ");
-               strcpy(buf + 5, command + dash); /* excluding "-" */
+               sprintf(buf, "exec %s", command); /* excluding "-" */
                /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
                cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash);
                cmd[1] = (char*)"-c";
                cmd[2] = buf;
                cmd[3] = NULL;
+               command = LIBBB_DEFAULT_LOGIN_SHELL + 1;
        } else {
                /* Convert command (char*) into cmd (char**, one word per string) */
                char *word, *next;
                int i = 0;
-               next = strcpy(buf, command); /* including "-" */
+               next = strcpy(buf, command - dash); /* command including "-" */
                while ((word = strsep(&next, " \t")) != NULL) {
                        if (*word != '\0') { /* not two spaces/tabs together? */
                                cmd[i] = word;
@@ -323,14 +424,14 @@ static void init_exec(const char *command)
        }
        /* If we saw leading "-", it is interactive shell.
         * Try harder to give it a controlling tty.
-        * And skip "-" in actual exec call. */
-       if (dash) {
+        */
+       if (ENABLE_FEATURE_INIT_SCTTY && dash) {
                /* _Attempt_ to make stdin a controlling tty. */
-               if (ENABLE_FEATURE_INIT_SCTTY)
-                       ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
+               ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
        }
-       BB_EXECVP(cmd[0] + dash, cmd);
-       message(L_LOG | L_CONSOLE, "can't run '%s': %s", cmd[0], strerror(errno));
+       /* Here command never contains the dash, cmd[0] might */
+       BB_EXECVP(command, cmd);
+       message(L_LOG | L_CONSOLE, "can't run '%s': %s", command, strerror(errno));
        /* returns if execvp fails */
 }
 
@@ -426,7 +527,9 @@ static struct init_action *mark_terminated(pid_t pid)
                                return a;
                        }
                }
-               update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
+               update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL,
+                               /*username:*/ NULL,
+                               /*hostname:*/ NULL);
        }
        return NULL;
 }
@@ -852,8 +955,6 @@ static int check_delayed_sigs(void)
 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int init_main(int argc UNUSED_PARAM, char **argv)
 {
-       die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
-
        if (argv[1] && strcmp(argv[1], "-q") == 0) {
                return kill(1, SIGHUP);
        }
@@ -861,9 +962,9 @@ int init_main(int argc UNUSED_PARAM, char **argv)
        if (!DEBUG_INIT) {
                /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
                if (getpid() != 1
-                && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
+                && (!ENABLE_FEATURE_INITRD || applet_name[0] != 'l') /* not linuxrc? */
                ) {
-                       bb_show_usage();
+                       bb_error_msg_and_die("must be run as PID 1");
                }
 #ifdef RB_DISABLE_CAD
                /* Turn off rebooting via CTL-ALT-DEL - we get a
@@ -872,6 +973,15 @@ int init_main(int argc UNUSED_PARAM, char **argv)
 #endif
        }
 
+       /* If, say, xmalloc would ever die, we don't want to oops kernel
+        * by exiting.
+        * NB: we set die_sleep *after* PID 1 check and bb_show_usage.
+        * Otherwise, for example, "init u" ("please rexec yourself"
+        * command for sysvinit) will show help text (which isn't too bad),
+        * *and sleep forever* (which is bad!)
+        */
+       die_sleep = 30 * 24*60*60;
+
        /* Figure out where the default console should be */
        console_init();
        set_sane_term();
@@ -939,7 +1049,7 @@ int init_main(int argc UNUSED_PARAM, char **argv)
                        /* SELinux in enforcing mode but load_policy failed */
                        message(L_CONSOLE, "can't load SELinux Policy. "
                                "Machine is in enforcing mode. Halting now.");
-                       exit(EXIT_FAILURE);
+                       return EXIT_FAILURE;
                }
        }
 #endif
@@ -1043,3 +1153,138 @@ int init_main(int argc UNUSED_PARAM, char **argv)
                }
        } /* while (1) */
 }
+
+//usage:#define linuxrc_trivial_usage NOUSAGE_STR
+//usage:#define linuxrc_full_usage ""
+
+//usage:#define init_trivial_usage
+//usage:       ""
+//usage:#define init_full_usage "\n\n"
+//usage:       "Init is the parent of all processes"
+//usage:
+//usage:#define init_notes_usage
+//usage:       "This version of init is designed to be run only by the kernel.\n"
+//usage:       "\n"
+//usage:       "BusyBox init doesn't support multiple runlevels. The runlevels field of\n"
+//usage:       "the /etc/inittab file is completely ignored by BusyBox init. If you want\n"
+//usage:       "runlevels, use sysvinit.\n"
+//usage:       "\n"
+//usage:       "BusyBox init works just fine without an inittab. If no inittab is found,\n"
+//usage:       "it has the following default behavior:\n"
+//usage:       "\n"
+//usage:       "       ::sysinit:/etc/init.d/rcS\n"
+//usage:       "       ::askfirst:/bin/sh\n"
+//usage:       "       ::ctrlaltdel:/sbin/reboot\n"
+//usage:       "       ::shutdown:/sbin/swapoff -a\n"
+//usage:       "       ::shutdown:/bin/umount -a -r\n"
+//usage:       "       ::restart:/sbin/init\n"
+//usage:       "\n"
+//usage:       "if it detects that /dev/console is _not_ a serial console, it will also run:\n"
+//usage:       "\n"
+//usage:       "       tty2::askfirst:/bin/sh\n"
+//usage:       "       tty3::askfirst:/bin/sh\n"
+//usage:       "       tty4::askfirst:/bin/sh\n"
+//usage:       "\n"
+//usage:       "If you choose to use an /etc/inittab file, the inittab entry format is as follows:\n"
+//usage:       "\n"
+//usage:       "       <id>:<runlevels>:<action>:<process>\n"
+//usage:       "\n"
+//usage:       "       <id>:\n"
+//usage:       "\n"
+//usage:       "               WARNING: This field has a non-traditional meaning for BusyBox init!\n"
+//usage:       "               The id field is used by BusyBox init to specify the controlling tty for\n"
+//usage:       "               the specified process to run on. The contents of this field are\n"
+//usage:       "               appended to \"/dev/\" and used as-is. There is no need for this field to\n"
+//usage:       "               be unique, although if it isn't you may have strange results. If this\n"
+//usage:       "               field is left blank, the controlling tty is set to the console. Also\n"
+//usage:       "               note that if BusyBox detects that a serial console is in use, then only\n"
+//usage:       "               entries whose controlling tty is either the serial console or /dev/null\n"
+//usage:       "               will be run. BusyBox init does nothing with utmp. We don't need no\n"
+//usage:       "               stinkin' utmp.\n"
+//usage:       "\n"
+//usage:       "       <runlevels>:\n"
+//usage:       "\n"
+//usage:       "               The runlevels field is completely ignored.\n"
+//usage:       "\n"
+//usage:       "       <action>:\n"
+//usage:       "\n"
+//usage:       "               Valid actions include: sysinit, respawn, askfirst, wait,\n"
+//usage:       "               once, restart, ctrlaltdel, and shutdown.\n"
+//usage:       "\n"
+//usage:       "               The available actions can be classified into two groups: actions\n"
+//usage:       "               that are run only once, and actions that are re-run when the specified\n"
+//usage:       "               process exits.\n"
+//usage:       "\n"
+//usage:       "               Run only-once actions:\n"
+//usage:       "\n"
+//usage:       "                       'sysinit' is the first item run on boot. init waits until all\n"
+//usage:       "                       sysinit actions are completed before continuing. Following the\n"
+//usage:       "                       completion of all sysinit actions, all 'wait' actions are run.\n"
+//usage:       "                       'wait' actions, like 'sysinit' actions, cause init to wait until\n"
+//usage:       "                       the specified task completes. 'once' actions are asynchronous,\n"
+//usage:       "                       therefore, init does not wait for them to complete. 'restart' is\n"
+//usage:       "                       the action taken to restart the init process. By default this should\n"
+//usage:       "                       simply run /sbin/init, but can be a script which runs pivot_root or it\n"
+//usage:       "                       can do all sorts of other interesting things. The 'ctrlaltdel' init\n"
+//usage:       "                       actions are run when the system detects that someone on the system\n"
+//usage:       "                       console has pressed the CTRL-ALT-DEL key combination. Typically one\n"
+//usage:       "                       wants to run 'reboot' at this point to cause the system to reboot.\n"
+//usage:       "                       Finally the 'shutdown' action specifies the actions to taken when\n"
+//usage:       "                       init is told to reboot. Unmounting filesystems and disabling swap\n"
+//usage:       "                       is a very good here.\n"
+//usage:       "\n"
+//usage:       "               Run repeatedly actions:\n"
+//usage:       "\n"
+//usage:       "                       'respawn' actions are run after the 'once' actions. When a process\n"
+//usage:       "                       started with a 'respawn' action exits, init automatically restarts\n"
+//usage:       "                       it. Unlike sysvinit, BusyBox init does not stop processes from\n"
+//usage:       "                       respawning out of control. The 'askfirst' actions acts just like\n"
+//usage:       "                       respawn, except that before running the specified process it\n"
+//usage:       "                       displays the line \"Please press Enter to activate this console.\"\n"
+//usage:       "                       and then waits for the user to press enter before starting the\n"
+//usage:       "                       specified process.\n"
+//usage:       "\n"
+//usage:       "               Unrecognized actions (like initdefault) will cause init to emit an\n"
+//usage:       "               error message, and then go along with its business. All actions are\n"
+//usage:       "               run in the order they appear in /etc/inittab.\n"
+//usage:       "\n"
+//usage:       "       <process>:\n"
+//usage:       "\n"
+//usage:       "               Specifies the process to be executed and its command line.\n"
+//usage:       "\n"
+//usage:       "Example /etc/inittab file:\n"
+//usage:       "\n"
+//usage:       "       # This is run first except when booting in single-user mode\n"
+//usage:       "       #\n"
+//usage:       "       ::sysinit:/etc/init.d/rcS\n"
+//usage:       "       \n"
+//usage:       "       # /bin/sh invocations on selected ttys\n"
+//usage:       "       #\n"
+//usage:       "       # Start an \"askfirst\" shell on the console (whatever that may be)\n"
+//usage:       "       ::askfirst:-/bin/sh\n"
+//usage:       "       # Start an \"askfirst\" shell on /dev/tty2-4\n"
+//usage:       "       tty2::askfirst:-/bin/sh\n"
+//usage:       "       tty3::askfirst:-/bin/sh\n"
+//usage:       "       tty4::askfirst:-/bin/sh\n"
+//usage:       "       \n"
+//usage:       "       # /sbin/getty invocations for selected ttys\n"
+//usage:       "       #\n"
+//usage:       "       tty4::respawn:/sbin/getty 38400 tty4\n"
+//usage:       "       tty5::respawn:/sbin/getty 38400 tty5\n"
+//usage:       "       \n"
+//usage:       "       \n"
+//usage:       "       # Example of how to put a getty on a serial line (for a terminal)\n"
+//usage:       "       #\n"
+//usage:       "       #::respawn:/sbin/getty -L ttyS0 9600 vt100\n"
+//usage:       "       #::respawn:/sbin/getty -L ttyS1 9600 vt100\n"
+//usage:       "       #\n"
+//usage:       "       # Example how to put a getty on a modem line\n"
+//usage:       "       #::respawn:/sbin/getty 57600 ttyS2\n"
+//usage:       "       \n"
+//usage:       "       # Stuff to do when restarting the init process\n"
+//usage:       "       ::restart:/sbin/init\n"
+//usage:       "       \n"
+//usage:       "       # Stuff to do before rebooting\n"
+//usage:       "       ::ctrlaltdel:/sbin/reboot\n"
+//usage:       "       ::shutdown:/bin/umount -a -r\n"
+//usage:       "       ::shutdown:/sbin/swapoff -a\n"