mirror of
https://github.com/sheumann/hush.git
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1289 lines
39 KiB
C
1289 lines
39 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini init implementation for busybox
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*
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* Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
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* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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* Adjusted by so many folks, it's impossible to keep track.
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//applet:IF_INIT(APPLET(init, _BB_DIR_SBIN, _BB_SUID_DROP))
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//applet:IF_FEATURE_INITRD(APPLET_ODDNAME(linuxrc, init, _BB_DIR_ROOT, _BB_SUID_DROP, linuxrc))
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//kbuild:lib-$(CONFIG_INIT) += init.o
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//config:config INIT
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//config: bool "init"
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//config: default y
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//config: select FEATURE_SYSLOG
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//config: help
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//config: init is the first program run when the system boots.
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//config:
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//config:config FEATURE_USE_INITTAB
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//config: bool "Support reading an inittab file"
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//config: default y
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//config: depends on INIT
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//config: help
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//config: Allow init to read an inittab file when the system boot.
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//config:
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//config:config FEATURE_KILL_REMOVED
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//config: bool "Support killing processes that have been removed from inittab"
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//config: default n
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//config: depends on FEATURE_USE_INITTAB
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//config: help
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//config: When respawn entries are removed from inittab and a SIGHUP is
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//config: sent to init, this option will make init kill the processes
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//config: that have been removed.
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//config:
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//config:config FEATURE_KILL_DELAY
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//config: int "How long to wait between TERM and KILL (0 - send TERM only)" if FEATURE_KILL_REMOVED
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//config: range 0 1024
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//config: default 0
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//config: depends on FEATURE_KILL_REMOVED
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//config: help
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//config: With nonzero setting, init sends TERM, forks, child waits N
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//config: seconds, sends KILL and exits. Setting it too high is unwise
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//config: (child will hang around for too long and could actually kill
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//config: the wrong process!)
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//config:
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//config:config FEATURE_INIT_SCTTY
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//config: bool "Run commands with leading dash with controlling tty"
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//config: default y
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//config: depends on INIT
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//config: help
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//config: If this option is enabled, init will try to give a controlling
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//config: tty to any command which has leading hyphen (often it's "-/bin/sh").
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//config: More precisely, init will do "ioctl(STDIN_FILENO, TIOCSCTTY, 0)".
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//config: If device attached to STDIN_FILENO can be a ctty but is not yet
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//config: a ctty for other session, it will become this process' ctty.
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//config: This is not the traditional init behavour, but is often what you want
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//config: in an embedded system where the console is only accessed during
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//config: development or for maintenance.
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//config: NB: using cttyhack applet may work better.
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//config:
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//config:config FEATURE_INIT_SYSLOG
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//config: bool "Enable init to write to syslog"
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//config: default y
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//config: depends on INIT
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//config:
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//config:config FEATURE_EXTRA_QUIET
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//config: bool "Be _extra_ quiet on boot"
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//config: default y
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//config: depends on INIT
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//config: help
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//config: Prevent init from logging some messages to the console during boot.
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//config:
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//config:config FEATURE_INIT_COREDUMPS
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//config: bool "Support dumping core for child processes (debugging only)"
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//config: default y
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//config: depends on INIT
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//config: help
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//config: If this option is enabled and the file /.init_enable_core
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//config: exists, then init will call setrlimit() to allow unlimited
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//config: core file sizes. If this option is disabled, processes
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//config: will not generate any core files.
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//config:
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//config:config FEATURE_INITRD
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//config: bool "Support running init from within an initrd (not initramfs)"
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//config: default y
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//config: depends on INIT
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//config: help
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//config: Legacy support for running init under the old-style initrd. Allows
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//config: the name linuxrc to act as init, and it doesn't assume init is PID 1.
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//config:
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//config: This does not apply to initramfs, which runs /init as PID 1 and
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//config: requires no special support.
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//config:
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//config:config INIT_TERMINAL_TYPE
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//config: string "Initial terminal type"
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//config: default "linux"
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//config: depends on INIT
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//config: help
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//config: This is the initial value set by init for the TERM environment
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//config: variable. This variable is used by programs which make use of
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//config: extended terminal capabilities.
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//config:
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//config: Note that on Linux, init attempts to detect serial terminal and
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//config: sets TERM to "vt102" if one is found.
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//usage:#define init_trivial_usage
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//usage: ""
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//usage:#define init_full_usage "\n\n"
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//usage: "Init is the parent of all processes"
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//usage:
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//usage:#define init_notes_usage
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//usage: "This version of init is designed to be run only by the kernel.\n"
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//usage: "\n"
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//usage: "BusyBox init doesn't support multiple runlevels. The runlevels field of\n"
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//usage: "the /etc/inittab file is completely ignored by BusyBox init. If you want\n"
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//usage: "runlevels, use sysvinit.\n"
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//usage: "\n"
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//usage: "BusyBox init works just fine without an inittab. If no inittab is found,\n"
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//usage: "it has the following default behavior:\n"
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//usage: "\n"
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//usage: " ::sysinit:/etc/init.d/rcS\n"
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//usage: " ::askfirst:/bin/sh\n"
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//usage: " ::ctrlaltdel:/sbin/reboot\n"
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//usage: " ::shutdown:/sbin/swapoff -a\n"
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//usage: " ::shutdown:/bin/umount -a -r\n"
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//usage: " ::restart:/sbin/init\n"
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//usage: "\n"
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//usage: "if it detects that /dev/console is _not_ a serial console, it will also run:\n"
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//usage: "\n"
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//usage: " tty2::askfirst:/bin/sh\n"
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//usage: " tty3::askfirst:/bin/sh\n"
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//usage: " tty4::askfirst:/bin/sh\n"
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//usage: "\n"
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//usage: "If you choose to use an /etc/inittab file, the inittab entry format is as follows:\n"
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//usage: "\n"
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//usage: " <id>:<runlevels>:<action>:<process>\n"
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//usage: "\n"
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//usage: " <id>:\n"
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//usage: "\n"
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//usage: " WARNING: This field has a non-traditional meaning for BusyBox init!\n"
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//usage: " The id field is used by BusyBox init to specify the controlling tty for\n"
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//usage: " the specified process to run on. The contents of this field are\n"
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//usage: " appended to \"/dev/\" and used as-is. There is no need for this field to\n"
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//usage: " be unique, although if it isn't you may have strange results. If this\n"
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//usage: " field is left blank, the controlling tty is set to the console. Also\n"
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//usage: " note that if BusyBox detects that a serial console is in use, then only\n"
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//usage: " entries whose controlling tty is either the serial console or /dev/null\n"
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//usage: " will be run. BusyBox init does nothing with utmp. We don't need no\n"
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//usage: " stinkin' utmp.\n"
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//usage: "\n"
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//usage: " <runlevels>:\n"
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//usage: "\n"
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//usage: " The runlevels field is completely ignored.\n"
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//usage: "\n"
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//usage: " <action>:\n"
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//usage: "\n"
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//usage: " Valid actions include: sysinit, respawn, askfirst, wait,\n"
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//usage: " once, restart, ctrlaltdel, and shutdown.\n"
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//usage: "\n"
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//usage: " The available actions can be classified into two groups: actions\n"
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//usage: " that are run only once, and actions that are re-run when the specified\n"
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//usage: " process exits.\n"
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//usage: "\n"
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//usage: " Run only-once actions:\n"
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//usage: "\n"
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//usage: " 'sysinit' is the first item run on boot. init waits until all\n"
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//usage: " sysinit actions are completed before continuing. Following the\n"
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//usage: " completion of all sysinit actions, all 'wait' actions are run.\n"
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//usage: " 'wait' actions, like 'sysinit' actions, cause init to wait until\n"
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//usage: " the specified task completes. 'once' actions are asynchronous,\n"
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//usage: " therefore, init does not wait for them to complete. 'restart' is\n"
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//usage: " the action taken to restart the init process. By default this should\n"
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//usage: " simply run /sbin/init, but can be a script which runs pivot_root or it\n"
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//usage: " can do all sorts of other interesting things. The 'ctrlaltdel' init\n"
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//usage: " actions are run when the system detects that someone on the system\n"
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//usage: " console has pressed the CTRL-ALT-DEL key combination. Typically one\n"
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//usage: " wants to run 'reboot' at this point to cause the system to reboot.\n"
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//usage: " Finally the 'shutdown' action specifies the actions to taken when\n"
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//usage: " init is told to reboot. Unmounting filesystems and disabling swap\n"
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//usage: " is a very good here.\n"
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//usage: "\n"
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//usage: " Run repeatedly actions:\n"
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//usage: "\n"
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//usage: " 'respawn' actions are run after the 'once' actions. When a process\n"
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//usage: " started with a 'respawn' action exits, init automatically restarts\n"
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//usage: " it. Unlike sysvinit, BusyBox init does not stop processes from\n"
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//usage: " respawning out of control. The 'askfirst' actions acts just like\n"
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//usage: " respawn, except that before running the specified process it\n"
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//usage: " displays the line \"Please press Enter to activate this console.\"\n"
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//usage: " and then waits for the user to press enter before starting the\n"
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//usage: " specified process.\n"
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//usage: "\n"
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//usage: " Unrecognized actions (like initdefault) will cause init to emit an\n"
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//usage: " error message, and then go along with its business. All actions are\n"
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//usage: " run in the order they appear in /etc/inittab.\n"
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//usage: "\n"
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//usage: " <process>:\n"
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//usage: "\n"
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//usage: " Specifies the process to be executed and its command line.\n"
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//usage: "\n"
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//usage: "Example /etc/inittab file:\n"
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//usage: "\n"
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//usage: " # This is run first except when booting in single-user mode\n"
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//usage: " #\n"
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//usage: " ::sysinit:/etc/init.d/rcS\n"
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//usage: " \n"
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//usage: " # /bin/sh invocations on selected ttys\n"
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//usage: " #\n"
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//usage: " # Start an \"askfirst\" shell on the console (whatever that may be)\n"
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//usage: " ::askfirst:-/bin/sh\n"
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//usage: " # Start an \"askfirst\" shell on /dev/tty2-4\n"
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//usage: " tty2::askfirst:-/bin/sh\n"
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//usage: " tty3::askfirst:-/bin/sh\n"
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//usage: " tty4::askfirst:-/bin/sh\n"
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//usage: " \n"
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//usage: " # /sbin/getty invocations for selected ttys\n"
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//usage: " #\n"
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//usage: " tty4::respawn:/sbin/getty 38400 tty4\n"
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//usage: " tty5::respawn:/sbin/getty 38400 tty5\n"
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//usage: " \n"
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//usage: " \n"
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//usage: " # Example of how to put a getty on a serial line (for a terminal)\n"
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//usage: " #\n"
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//usage: " #::respawn:/sbin/getty -L ttyS0 9600 vt100\n"
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//usage: " #::respawn:/sbin/getty -L ttyS1 9600 vt100\n"
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//usage: " #\n"
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//usage: " # Example how to put a getty on a modem line\n"
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//usage: " #::respawn:/sbin/getty 57600 ttyS2\n"
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//usage: " \n"
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//usage: " # Stuff to do when restarting the init process\n"
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//usage: " ::restart:/sbin/init\n"
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//usage: " \n"
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//usage: " # Stuff to do before rebooting\n"
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//usage: " ::ctrlaltdel:/sbin/reboot\n"
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//usage: " ::shutdown:/bin/umount -a -r\n"
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//usage: " ::shutdown:/sbin/swapoff -a\n"
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#include "libbb.h"
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#include <syslog.h>
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#include <paths.h>
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#include <sys/resource.h>
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#ifdef __linux__
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#include <linux/vt.h>
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#endif
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#if ENABLE_FEATURE_UTMP
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# include <utmp.h> /* DEAD_PROCESS */
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#endif
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#include "reboot.h" /* reboot() constants */
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/* Used only for sanitizing purposes in set_sane_term() below. On systems where
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* the baud rate is stored in a separate field, we can safely disable them. */
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#ifndef CBAUD
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# define CBAUD 0
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# define CBAUDEX 0
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#endif
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/* Was a CONFIG_xxx option. A lot of people were building
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* not fully functional init by switching it on! */
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#define DEBUG_INIT 0
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#define COMMAND_SIZE 256
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#define CONSOLE_NAME_SIZE 32
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/* Default sysinit script. */
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#ifndef INIT_SCRIPT
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#define INIT_SCRIPT "/etc/init.d/rcS"
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#endif
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/* Each type of actions can appear many times. They will be
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* handled in order. RESTART is an exception, only 1st is used.
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*/
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/* Start these actions first and wait for completion */
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#define SYSINIT 0x01
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/* Start these after SYSINIT and wait for completion */
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#define WAIT 0x02
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/* Start these after WAIT and *dont* wait for completion */
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#define ONCE 0x04
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/*
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* NB: while SYSINIT/WAIT/ONCE are being processed,
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* SIGHUP ("reread /etc/inittab") will be processed only after
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* each group of actions. If new inittab adds, say, a SYSINIT action,
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* it will not be run, since init is already "past SYSINIT stage".
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*/
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/* Start these after ONCE are started, restart on exit */
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#define RESPAWN 0x08
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/* Like RESPAWN, but wait for <Enter> to be pressed on tty */
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#define ASKFIRST 0x10
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/*
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* Start these on SIGINT, and wait for completion.
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* Then go back to respawning RESPAWN and ASKFIRST actions.
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* NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed.
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*/
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#define CTRLALTDEL 0x20
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/*
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* Start these before killing all processes in preparation for
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* running RESTART actions or doing low-level halt/reboot/poweroff
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* (initiated by SIGUSR1/SIGTERM/SIGUSR2).
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* Wait for completion before proceeding.
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*/
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#define SHUTDOWN 0x40
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/*
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* exec() on SIGQUIT. SHUTDOWN actions are started and waited for,
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* then all processes are killed, then init exec's 1st RESTART action,
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* replacing itself by it. If no RESTART action specified,
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* SIGQUIT has no effect.
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*/
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#define RESTART 0x80
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/* A linked list of init_actions, to be read from inittab */
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struct init_action {
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struct init_action *next;
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pid_t pid;
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uint8_t action_type;
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char terminal[CONSOLE_NAME_SIZE];
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char command[COMMAND_SIZE];
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};
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static struct init_action *init_action_list = NULL;
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static const char *log_console = VC_5;
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enum {
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L_LOG = 0x1,
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L_CONSOLE = 0x2,
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};
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/* Print a message to the specified device.
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* "where" may be bitwise-or'd from L_LOG | L_CONSOLE
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* NB: careful, we can be called after vfork!
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*/
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#define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
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static void message(int where, const char *fmt, ...)
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__attribute__ ((format(printf, 2, 3)));
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static void message(int where, const char *fmt, ...)
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{
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va_list arguments;
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unsigned l;
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char msg[128];
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msg[0] = '\r';
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va_start(arguments, fmt);
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l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
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if (l > sizeof(msg) - 1)
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l = sizeof(msg) - 1;
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va_end(arguments);
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#if ENABLE_FEATURE_INIT_SYSLOG
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msg[l] = '\0';
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if (where & L_LOG) {
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/* Log the message to syslogd */
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openlog(applet_name, 0, LOG_DAEMON);
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/* don't print "\r" */
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syslog(LOG_INFO, "%s", msg + 1);
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closelog();
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}
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msg[l++] = '\n';
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msg[l] = '\0';
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#else
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{
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static int log_fd = -1;
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msg[l++] = '\n';
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msg[l] = '\0';
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/* Take full control of the log tty, and never close it.
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* It's mine, all mine! Muhahahaha! */
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if (log_fd < 0) {
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if (!log_console) {
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log_fd = STDERR_FILENO;
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} else {
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log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY);
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if (log_fd < 0) {
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bb_error_msg("can't log to %s", log_console);
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where = L_CONSOLE;
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} else {
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close_on_exec_on(log_fd);
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}
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}
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}
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if (where & L_LOG) {
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full_write(log_fd, msg, l);
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if (log_fd == STDERR_FILENO)
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return; /* don't print dup messages */
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}
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}
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#endif
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if (where & L_CONSOLE) {
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/* Send console messages to console so people will see them. */
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full_write(STDERR_FILENO, msg, l);
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}
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}
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static void console_init(void)
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{
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#ifdef VT_OPENQRY
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int vtno;
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#endif
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char *s;
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s = getenv("CONSOLE");
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if (!s)
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s = getenv("console");
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if (s) {
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int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY);
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if (fd >= 0) {
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dup2(fd, STDIN_FILENO);
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dup2(fd, STDOUT_FILENO);
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xmove_fd(fd, STDERR_FILENO);
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}
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dbg_message(L_LOG, "console='%s'", s);
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} else {
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/* Make sure fd 0,1,2 are not closed
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* (so that they won't be used by future opens) */
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bb_sanitize_stdio();
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// Users report problems
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// /* Make sure init can't be blocked by writing to stderr */
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// fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK);
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}
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s = getenv("TERM");
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#ifdef VT_OPENQRY
|
|
if (ioctl(STDIN_FILENO, VT_OPENQRY, &vtno) != 0) {
|
|
/* Not a linux terminal, probably serial console.
|
|
* Force the TERM setting to vt102
|
|
* if TERM is set to linux (the default) */
|
|
if (!s || strcmp(s, "linux") == 0)
|
|
putenv((char*)"TERM=vt102");
|
|
if (!ENABLE_FEATURE_INIT_SYSLOG)
|
|
log_console = NULL;
|
|
} else
|
|
#endif
|
|
if (!s)
|
|
putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE);
|
|
}
|
|
|
|
/* Set terminal settings to reasonable defaults.
|
|
* NB: careful, we can be called after vfork! */
|
|
static void set_sane_term(void)
|
|
{
|
|
struct termios tty;
|
|
|
|
tcgetattr(STDIN_FILENO, &tty);
|
|
|
|
/* set control chars */
|
|
tty.c_cc[VINTR] = 3; /* C-c */
|
|
tty.c_cc[VQUIT] = 28; /* C-\ */
|
|
tty.c_cc[VERASE] = 127; /* C-? */
|
|
tty.c_cc[VKILL] = 21; /* C-u */
|
|
tty.c_cc[VEOF] = 4; /* C-d */
|
|
tty.c_cc[VSTART] = 17; /* C-q */
|
|
tty.c_cc[VSTOP] = 19; /* C-s */
|
|
tty.c_cc[VSUSP] = 26; /* C-z */
|
|
|
|
#ifdef __linux__
|
|
/* use line discipline 0 */
|
|
tty.c_line = 0;
|
|
#endif
|
|
|
|
/* Make it be sane */
|
|
#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 */
|
|
tty.c_iflag = ICRNL | IXON | IXOFF;
|
|
|
|
/* output modes */
|
|
tty.c_oflag = OPOST | ONLCR;
|
|
|
|
/* local modes */
|
|
tty.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
|
|
|
|
tcsetattr_stdin_TCSANOW(&tty);
|
|
}
|
|
|
|
/* Open the new terminal device.
|
|
* NB: careful, we can be called after vfork! */
|
|
static int open_stdio_to_tty(const char* tty_name)
|
|
{
|
|
/* empty tty_name means "use init's tty", else... */
|
|
if (tty_name[0]) {
|
|
int fd;
|
|
|
|
close(STDIN_FILENO);
|
|
/* fd can be only < 0 or 0: */
|
|
fd = device_open(tty_name, O_RDWR);
|
|
if (fd) {
|
|
message(L_LOG | L_CONSOLE, "can't open %s: %s",
|
|
tty_name, strerror(errno));
|
|
return 0; /* failure */
|
|
}
|
|
dup2(STDIN_FILENO, STDOUT_FILENO);
|
|
dup2(STDIN_FILENO, STDERR_FILENO);
|
|
}
|
|
set_sane_term();
|
|
return 1; /* success */
|
|
}
|
|
|
|
static void reset_sighandlers_and_unblock_sigs(void)
|
|
{
|
|
bb_signals(0
|
|
+ (1 << SIGUSR1)
|
|
+ (1 << SIGUSR2)
|
|
+ (1 << SIGTERM)
|
|
+ (1 << SIGQUIT)
|
|
+ (1 << SIGINT)
|
|
+ (1 << SIGHUP)
|
|
+ (1 << SIGTSTP)
|
|
+ (1 << SIGSTOP)
|
|
, SIG_DFL);
|
|
sigprocmask_allsigs(SIG_UNBLOCK);
|
|
}
|
|
|
|
/* Wrapper around exec:
|
|
* Takes string (max COMMAND_SIZE chars).
|
|
* If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
|
|
* Otherwise splits words on whitespace, deals with leading dash,
|
|
* and uses plain exec().
|
|
* NB: careful, we can be called after vfork!
|
|
*/
|
|
static void init_exec(const char *command)
|
|
{
|
|
char *cmd[COMMAND_SIZE / 2];
|
|
char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
|
|
int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
|
|
|
|
/* See if any special /bin/sh requiring characters are present */
|
|
if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
|
|
strcpy(buf, "exec ");
|
|
strcpy(buf + 5, command + dash); /* 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;
|
|
} else {
|
|
/* Convert command (char*) into cmd (char**, one word per string) */
|
|
char *word, *next;
|
|
int i = 0;
|
|
next = strcpy(buf, command); /* including "-" */
|
|
while ((word = strsep(&next, " \t")) != NULL) {
|
|
if (*word != '\0') { /* not two spaces/tabs together? */
|
|
cmd[i] = word;
|
|
i++;
|
|
}
|
|
}
|
|
cmd[i] = NULL;
|
|
}
|
|
/* If we saw leading "-", it is interactive shell.
|
|
* Try harder to give it a controlling tty.
|
|
* And skip "-" in actual exec call. */
|
|
if (dash) {
|
|
/* _Attempt_ to make stdin a controlling tty. */
|
|
if (ENABLE_FEATURE_INIT_SCTTY)
|
|
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));
|
|
/* returns if execvp fails */
|
|
}
|
|
|
|
/* Used only by run_actions */
|
|
static pid_t run(const struct init_action *a)
|
|
{
|
|
pid_t pid;
|
|
|
|
/* Careful: don't be affected by a signal in vforked child */
|
|
sigprocmask_allsigs(SIG_BLOCK);
|
|
if (BB_MMU && (a->action_type & ASKFIRST))
|
|
pid = fork();
|
|
else
|
|
pid = vfork();
|
|
if (pid < 0)
|
|
message(L_LOG | L_CONSOLE, "can't fork");
|
|
if (pid) {
|
|
sigprocmask_allsigs(SIG_UNBLOCK);
|
|
return pid; /* Parent or error */
|
|
}
|
|
|
|
/* Child */
|
|
|
|
/* Reset signal handlers that were set by the parent process */
|
|
reset_sighandlers_and_unblock_sigs();
|
|
|
|
/* Create a new session and make ourself the process group leader */
|
|
setsid();
|
|
|
|
/* Open the new terminal device */
|
|
if (!open_stdio_to_tty(a->terminal))
|
|
_exit(EXIT_FAILURE);
|
|
|
|
/* NB: on NOMMU we can't wait for input in child, so
|
|
* "askfirst" will work the same as "respawn". */
|
|
if (BB_MMU && (a->action_type & ASKFIRST)) {
|
|
static const char press_enter[] ALIGN1 =
|
|
#ifdef CUSTOMIZED_BANNER
|
|
#include CUSTOMIZED_BANNER
|
|
#endif
|
|
"\nPlease press Enter to activate this console. ";
|
|
char c;
|
|
/*
|
|
* Save memory by not exec-ing anything large (like a shell)
|
|
* before the user wants it. This is critical if swap is not
|
|
* enabled and the system has low memory. Generally this will
|
|
* be run on the second virtual console, and the first will
|
|
* be allowed to start a shell or whatever an init script
|
|
* specifies.
|
|
*/
|
|
dbg_message(L_LOG, "waiting for enter to start '%s'"
|
|
"(pid %d, tty '%s')\n",
|
|
a->command, getpid(), a->terminal);
|
|
full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1);
|
|
while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n')
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* When a file named /.init_enable_core exists, setrlimit is called
|
|
* before processes are spawned to set core file size as unlimited.
|
|
* This is for debugging only. Don't use this is production, unless
|
|
* you want core dumps lying about....
|
|
*/
|
|
if (ENABLE_FEATURE_INIT_COREDUMPS) {
|
|
if (access("/.init_enable_core", F_OK) == 0) {
|
|
struct rlimit limit;
|
|
limit.rlim_cur = RLIM_INFINITY;
|
|
limit.rlim_max = RLIM_INFINITY;
|
|
setrlimit(RLIMIT_CORE, &limit);
|
|
}
|
|
}
|
|
|
|
/* Log the process name and args */
|
|
message(L_LOG, "starting pid %d, tty '%s': '%s'",
|
|
getpid(), a->terminal, a->command);
|
|
|
|
/* Now run it. The new program will take over this PID,
|
|
* so nothing further in init.c should be run. */
|
|
init_exec(a->command);
|
|
/* We're still here? Some error happened. */
|
|
_exit(-1);
|
|
}
|
|
|
|
static struct init_action *mark_terminated(pid_t pid)
|
|
{
|
|
struct init_action *a;
|
|
|
|
if (pid > 0) {
|
|
for (a = init_action_list; a; a = a->next) {
|
|
if (a->pid == pid) {
|
|
a->pid = 0;
|
|
return a;
|
|
}
|
|
}
|
|
update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL,
|
|
/*username:*/ NULL,
|
|
/*hostname:*/ NULL);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static void waitfor(pid_t pid)
|
|
{
|
|
/* waitfor(run(x)): protect against failed fork inside run() */
|
|
if (pid <= 0)
|
|
return;
|
|
|
|
/* Wait for any child (prevent zombies from exiting orphaned processes)
|
|
* but exit the loop only when specified one has exited. */
|
|
while (1) {
|
|
pid_t wpid = wait(NULL);
|
|
mark_terminated(wpid);
|
|
/* Unsafe. SIGTSTP handler might have wait'ed it already */
|
|
/*if (wpid == pid) break;*/
|
|
/* More reliable: */
|
|
if (kill(pid, 0))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Run all commands of a particular type */
|
|
static void run_actions(int action_type)
|
|
{
|
|
struct init_action *a;
|
|
|
|
for (a = init_action_list; a; a = a->next) {
|
|
if (!(a->action_type & action_type))
|
|
continue;
|
|
|
|
if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
|
|
pid_t pid = run(a);
|
|
if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
|
|
waitfor(pid);
|
|
}
|
|
if (a->action_type & (RESPAWN | ASKFIRST)) {
|
|
/* Only run stuff with pid == 0. If pid != 0,
|
|
* it is already running
|
|
*/
|
|
if (a->pid == 0)
|
|
a->pid = run(a);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void new_init_action(uint8_t action_type, const char *command, const char *cons)
|
|
{
|
|
struct init_action *a, **nextp;
|
|
|
|
/* Scenario:
|
|
* old inittab:
|
|
* ::shutdown:umount -a -r
|
|
* ::shutdown:swapoff -a
|
|
* new inittab:
|
|
* ::shutdown:swapoff -a
|
|
* ::shutdown:umount -a -r
|
|
* On reload, we must ensure entries end up in correct order.
|
|
* To achieve that, if we find a matching entry, we move it
|
|
* to the end.
|
|
*/
|
|
nextp = &init_action_list;
|
|
while ((a = *nextp) != NULL) {
|
|
/* Don't enter action if it's already in the list,
|
|
* This prevents losing running RESPAWNs.
|
|
*/
|
|
if (strcmp(a->command, command) == 0
|
|
&& strcmp(a->terminal, cons) == 0
|
|
) {
|
|
/* Remove from list */
|
|
*nextp = a->next;
|
|
/* Find the end of the list */
|
|
while (*nextp != NULL)
|
|
nextp = &(*nextp)->next;
|
|
a->next = NULL;
|
|
break;
|
|
}
|
|
nextp = &a->next;
|
|
}
|
|
|
|
if (!a)
|
|
a = xzalloc(sizeof(*a));
|
|
/* Append to the end of the list */
|
|
*nextp = a;
|
|
a->action_type = action_type;
|
|
safe_strncpy(a->command, command, sizeof(a->command));
|
|
safe_strncpy(a->terminal, cons, sizeof(a->terminal));
|
|
dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
|
|
a->command, a->action_type, a->terminal);
|
|
}
|
|
|
|
/* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
|
|
* then parse_inittab() simply adds in some default
|
|
* actions(i.e., runs INIT_SCRIPT and then starts a pair
|
|
* of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB
|
|
* _is_ defined, but /etc/inittab is missing, this
|
|
* results in the same set of default behaviors.
|
|
*/
|
|
static void parse_inittab(void)
|
|
{
|
|
#if ENABLE_FEATURE_USE_INITTAB
|
|
char *token[4];
|
|
parser_t *parser = config_open2("/etc/inittab", fopen_for_read);
|
|
|
|
if (parser == NULL)
|
|
#endif
|
|
{
|
|
/* No inittab file - set up some default behavior */
|
|
/* Reboot on Ctrl-Alt-Del */
|
|
new_init_action(CTRLALTDEL, "reboot", "");
|
|
/* Umount all filesystems on halt/reboot */
|
|
new_init_action(SHUTDOWN, "umount -a -r", "");
|
|
/* Swapoff on halt/reboot */
|
|
if (ENABLE_SWAPONOFF)
|
|
new_init_action(SHUTDOWN, "swapoff -a", "");
|
|
/* Prepare to restart init when a QUIT is received */
|
|
new_init_action(RESTART, "init", "");
|
|
/* Askfirst shell on tty1-4 */
|
|
new_init_action(ASKFIRST, bb_default_login_shell, "");
|
|
//TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users
|
|
new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
|
|
new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
|
|
new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
|
|
/* sysinit */
|
|
new_init_action(SYSINIT, INIT_SCRIPT, "");
|
|
return;
|
|
}
|
|
|
|
#if ENABLE_FEATURE_USE_INITTAB
|
|
/* optional_tty:ignored_runlevel:action:command
|
|
* Delims are not to be collapsed and need exactly 4 tokens
|
|
*/
|
|
while (config_read(parser, token, 4, 0, "#:",
|
|
PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) {
|
|
/* order must correspond to SYSINIT..RESTART constants */
|
|
static const char actions[] ALIGN1 =
|
|
"sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
|
|
"ctrlaltdel\0""shutdown\0""restart\0";
|
|
int action;
|
|
char *tty = token[0];
|
|
|
|
if (!token[3]) /* less than 4 tokens */
|
|
goto bad_entry;
|
|
action = index_in_strings(actions, token[2]);
|
|
if (action < 0 || !token[3][0]) /* token[3]: command */
|
|
goto bad_entry;
|
|
/* turn .*TTY -> /dev/TTY */
|
|
if (tty[0]) {
|
|
tty = concat_path_file("/dev/", skip_dev_pfx(tty));
|
|
}
|
|
new_init_action(1 << action, token[3], tty);
|
|
if (tty[0])
|
|
free(tty);
|
|
continue;
|
|
bad_entry:
|
|
message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d",
|
|
parser->lineno);
|
|
}
|
|
config_close(parser);
|
|
#endif
|
|
}
|
|
|
|
static void pause_and_low_level_reboot(unsigned magic) NORETURN;
|
|
static void pause_and_low_level_reboot(unsigned magic)
|
|
{
|
|
pid_t pid;
|
|
|
|
/* Allow time for last message to reach serial console, etc */
|
|
sleep(1);
|
|
|
|
/* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
|
|
* in linux/kernel/sys.c, which can cause the machine to panic when
|
|
* the init process exits... */
|
|
pid = vfork();
|
|
if (pid == 0) { /* child */
|
|
reboot(magic);
|
|
_exit(EXIT_SUCCESS);
|
|
}
|
|
while (1)
|
|
sleep(1);
|
|
}
|
|
|
|
static void run_shutdown_and_kill_processes(void)
|
|
{
|
|
/* Run everything to be run at "shutdown". This is done _prior_
|
|
* to killing everything, in case people wish to use scripts to
|
|
* shut things down gracefully... */
|
|
run_actions(SHUTDOWN);
|
|
|
|
message(L_CONSOLE | L_LOG, "The system is going down NOW!");
|
|
|
|
/* Send signals to every process _except_ pid 1 */
|
|
kill(-1, SIGTERM);
|
|
message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
|
|
sync();
|
|
sleep(1);
|
|
|
|
kill(-1, SIGKILL);
|
|
message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
|
|
sync();
|
|
/*sleep(1); - callers take care about making a pause */
|
|
}
|
|
|
|
/* Signal handling by init:
|
|
*
|
|
* For process with PID==1, on entry kernel sets all signals to SIG_DFL
|
|
* and unmasks all signals. However, for process with PID==1,
|
|
* default action (SIG_DFL) on any signal is to ignore it,
|
|
* even for special signals SIGKILL and SIGCONT.
|
|
* Also, any signal can be caught or blocked.
|
|
* (but SIGSTOP is still handled specially, at least in 2.6.20)
|
|
*
|
|
* We install two kinds of handlers, "immediate" and "delayed".
|
|
*
|
|
* Immediate handlers execute at any time, even while, say, sysinit
|
|
* is running.
|
|
*
|
|
* Delayed handlers just set a flag variable. The variable is checked
|
|
* in the main loop and acted upon.
|
|
*
|
|
* halt/poweroff/reboot and restart have immediate handlers.
|
|
* They only traverse linked list of struct action's, never modify it,
|
|
* this should be safe to do even in signal handler. Also they
|
|
* never return.
|
|
*
|
|
* SIGSTOP and SIGTSTP have immediate handlers. They just wait
|
|
* for SIGCONT to happen.
|
|
*
|
|
* SIGHUP has a delayed handler, because modifying linked list
|
|
* of struct action's from a signal handler while it is manipulated
|
|
* by the program may be disastrous.
|
|
*
|
|
* Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
|
|
* it to happen even somewhere inside "sysinit" would be a bit awkward.
|
|
*
|
|
* There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
|
|
* and only one will be remembered and acted upon.
|
|
*/
|
|
|
|
/* The SIGUSR[12]/SIGTERM handler */
|
|
static void halt_reboot_pwoff(int sig) NORETURN;
|
|
static void halt_reboot_pwoff(int sig)
|
|
{
|
|
const char *m;
|
|
unsigned rb;
|
|
|
|
/* We may call run() and it unmasks signals,
|
|
* including the one masked inside this signal handler.
|
|
* Testcase which would start multiple reboot scripts:
|
|
* while true; do reboot; done
|
|
* Preventing it:
|
|
*/
|
|
reset_sighandlers_and_unblock_sigs();
|
|
|
|
run_shutdown_and_kill_processes();
|
|
|
|
m = "halt";
|
|
rb = RB_HALT_SYSTEM;
|
|
if (sig == SIGTERM) {
|
|
m = "reboot";
|
|
rb = RB_AUTOBOOT;
|
|
} else if (sig == SIGUSR2) {
|
|
m = "poweroff";
|
|
rb = RB_POWER_OFF;
|
|
}
|
|
message(L_CONSOLE, "Requesting system %s", m);
|
|
pause_and_low_level_reboot(rb);
|
|
/* not reached */
|
|
}
|
|
|
|
/* Handler for QUIT - exec "restart" action,
|
|
* else (no such action defined) do nothing */
|
|
static void restart_handler(int sig UNUSED_PARAM)
|
|
{
|
|
struct init_action *a;
|
|
|
|
for (a = init_action_list; a; a = a->next) {
|
|
if (!(a->action_type & RESTART))
|
|
continue;
|
|
|
|
/* Starting from here, we won't return.
|
|
* Thus don't need to worry about preserving errno
|
|
* and such.
|
|
*/
|
|
|
|
reset_sighandlers_and_unblock_sigs();
|
|
|
|
run_shutdown_and_kill_processes();
|
|
|
|
#ifdef RB_ENABLE_CAD
|
|
/* Allow Ctrl-Alt-Del to reboot the system.
|
|
* This is how kernel sets it up for init, we follow suit.
|
|
*/
|
|
reboot(RB_ENABLE_CAD); /* misnomer */
|
|
#endif
|
|
|
|
if (open_stdio_to_tty(a->terminal)) {
|
|
dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
|
|
/* Theoretically should be safe.
|
|
* But in practice, kernel bugs may leave
|
|
* unkillable processes, and wait() may block forever.
|
|
* Oh well. Hoping "new" init won't be too surprised
|
|
* by having children it didn't create.
|
|
*/
|
|
//while (wait(NULL) > 0)
|
|
// continue;
|
|
init_exec(a->command);
|
|
}
|
|
/* Open or exec failed */
|
|
pause_and_low_level_reboot(RB_HALT_SYSTEM);
|
|
/* not reached */
|
|
}
|
|
}
|
|
|
|
/* The SIGSTOP/SIGTSTP handler
|
|
* NB: inside it, all signals except SIGCONT are masked
|
|
* via appropriate setup in sigaction().
|
|
*/
|
|
static void stop_handler(int sig UNUSED_PARAM)
|
|
{
|
|
smallint saved_bb_got_signal;
|
|
int saved_errno;
|
|
|
|
saved_bb_got_signal = bb_got_signal;
|
|
saved_errno = errno;
|
|
signal(SIGCONT, record_signo);
|
|
|
|
while (1) {
|
|
pid_t wpid;
|
|
|
|
if (bb_got_signal == SIGCONT)
|
|
break;
|
|
/* NB: this can accidentally wait() for a process
|
|
* which we waitfor() elsewhere! waitfor() must have
|
|
* code which is resilient against this.
|
|
*/
|
|
wpid = wait_any_nohang(NULL);
|
|
mark_terminated(wpid);
|
|
sleep(1);
|
|
}
|
|
|
|
signal(SIGCONT, SIG_DFL);
|
|
errno = saved_errno;
|
|
bb_got_signal = saved_bb_got_signal;
|
|
}
|
|
|
|
#if ENABLE_FEATURE_USE_INITTAB
|
|
static void reload_inittab(void)
|
|
{
|
|
struct init_action *a, **nextp;
|
|
|
|
message(L_LOG, "reloading /etc/inittab");
|
|
|
|
/* Disable old entries */
|
|
for (a = init_action_list; a; a = a->next)
|
|
a->action_type = 0;
|
|
|
|
/* Append new entries, or modify existing entries
|
|
* (incl. setting a->action_type) if cmd and device name
|
|
* match new ones. End result: only entries with
|
|
* a->action_type == 0 are stale.
|
|
*/
|
|
parse_inittab();
|
|
|
|
#if ENABLE_FEATURE_KILL_REMOVED
|
|
/* Kill stale entries */
|
|
/* Be nice and send SIGTERM first */
|
|
for (a = init_action_list; a; a = a->next)
|
|
if (a->action_type == 0 && a->pid != 0)
|
|
kill(a->pid, SIGTERM);
|
|
if (CONFIG_FEATURE_KILL_DELAY) {
|
|
/* NB: parent will wait in NOMMU case */
|
|
if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
|
|
sleep(CONFIG_FEATURE_KILL_DELAY);
|
|
for (a = init_action_list; a; a = a->next)
|
|
if (a->action_type == 0 && a->pid != 0)
|
|
kill(a->pid, SIGKILL);
|
|
_exit(EXIT_SUCCESS);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Remove stale entries and SYSINIT entries.
|
|
* We never rerun SYSINIT entries anyway,
|
|
* removing them too saves a few bytes */
|
|
nextp = &init_action_list;
|
|
while ((a = *nextp) != NULL) {
|
|
if ((a->action_type & ~SYSINIT) == 0) {
|
|
*nextp = a->next;
|
|
free(a);
|
|
} else {
|
|
nextp = &a->next;
|
|
}
|
|
}
|
|
|
|
/* Not needed: */
|
|
/* run_actions(RESPAWN | ASKFIRST); */
|
|
/* - we return to main loop, which does this automagically */
|
|
}
|
|
#endif
|
|
|
|
static int check_delayed_sigs(void)
|
|
{
|
|
int sigs_seen = 0;
|
|
|
|
while (1) {
|
|
smallint sig = bb_got_signal;
|
|
|
|
if (!sig)
|
|
return sigs_seen;
|
|
bb_got_signal = 0;
|
|
sigs_seen = 1;
|
|
#if ENABLE_FEATURE_USE_INITTAB
|
|
if (sig == SIGHUP)
|
|
reload_inittab();
|
|
#endif
|
|
if (sig == SIGINT)
|
|
run_actions(CTRLALTDEL);
|
|
}
|
|
}
|
|
|
|
int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
|
int init_main(int argc UNUSED_PARAM, char **argv)
|
|
{
|
|
if (argv[1] && strcmp(argv[1], "-q") == 0) {
|
|
return kill(1, SIGHUP);
|
|
}
|
|
|
|
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"))
|
|
) {
|
|
bb_show_usage();
|
|
}
|
|
#ifdef RB_DISABLE_CAD
|
|
/* Turn off rebooting via CTL-ALT-DEL - we get a
|
|
* SIGINT on CAD so we can shut things down gracefully... */
|
|
reboot(RB_DISABLE_CAD); /* misnomer */
|
|
#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();
|
|
xchdir("/");
|
|
setsid();
|
|
|
|
/* Make sure environs is set to something sane */
|
|
putenv((char *) "HOME=/");
|
|
putenv((char *) bb_PATH_root_path);
|
|
putenv((char *) "SHELL=/bin/sh");
|
|
putenv((char *) "USER=root"); /* needed? why? */
|
|
|
|
if (argv[1])
|
|
xsetenv("RUNLEVEL", argv[1]);
|
|
|
|
#if !ENABLE_FEATURE_EXTRA_QUIET
|
|
/* Hello world */
|
|
message(L_CONSOLE | L_LOG, "init started: %s", bb_banner);
|
|
#endif
|
|
|
|
/* struct sysinfo is linux-specific */
|
|
#ifdef __linux__
|
|
/* Make sure there is enough memory to do something useful. */
|
|
if (ENABLE_SWAPONOFF) {
|
|
struct sysinfo info;
|
|
|
|
if (sysinfo(&info) == 0
|
|
&& (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024
|
|
) {
|
|
message(L_CONSOLE, "Low memory, forcing swapon");
|
|
/* swapon -a requires /proc typically */
|
|
new_init_action(SYSINIT, "mount -t proc proc /proc", "");
|
|
/* Try to turn on swap */
|
|
new_init_action(SYSINIT, "swapon -a", "");
|
|
run_actions(SYSINIT); /* wait and removing */
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Check if we are supposed to be in single user mode */
|
|
if (argv[1]
|
|
&& (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1'))
|
|
) {
|
|
/* ??? shouldn't we set RUNLEVEL="b" here? */
|
|
/* Start a shell on console */
|
|
new_init_action(RESPAWN, bb_default_login_shell, "");
|
|
} else {
|
|
/* Not in single user mode - see what inittab says */
|
|
|
|
/* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
|
|
* then parse_inittab() simply adds in some default
|
|
* actions(i.e., INIT_SCRIPT and a pair
|
|
* of "askfirst" shells */
|
|
parse_inittab();
|
|
}
|
|
|
|
#if ENABLE_SELINUX
|
|
if (getenv("SELINUX_INIT") == NULL) {
|
|
int enforce = 0;
|
|
|
|
putenv((char*)"SELINUX_INIT=YES");
|
|
if (selinux_init_load_policy(&enforce) == 0) {
|
|
BB_EXECVP(argv[0], argv);
|
|
} else if (enforce > 0) {
|
|
/* SELinux in enforcing mode but load_policy failed */
|
|
message(L_CONSOLE, "can't load SELinux Policy. "
|
|
"Machine is in enforcing mode. Halting now.");
|
|
return EXIT_FAILURE;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Make the command line just say "init" - thats all, nothing else */
|
|
strncpy(argv[0], "init", strlen(argv[0]));
|
|
/* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
|
|
while (*++argv)
|
|
memset(*argv, 0, strlen(*argv));
|
|
|
|
/* Set up signal handlers */
|
|
if (!DEBUG_INIT) {
|
|
struct sigaction sa;
|
|
|
|
bb_signals(0
|
|
+ (1 << SIGUSR1) /* halt */
|
|
+ (1 << SIGTERM) /* reboot */
|
|
+ (1 << SIGUSR2) /* poweroff */
|
|
, halt_reboot_pwoff);
|
|
signal(SIGQUIT, restart_handler); /* re-exec another init */
|
|
|
|
/* Stop handler must allow only SIGCONT inside itself */
|
|
memset(&sa, 0, sizeof(sa));
|
|
sigfillset(&sa.sa_mask);
|
|
sigdelset(&sa.sa_mask, SIGCONT);
|
|
sa.sa_handler = stop_handler;
|
|
/* NB: sa_flags doesn't have SA_RESTART.
|
|
* It must be able to interrupt wait().
|
|
*/
|
|
sigaction_set(SIGTSTP, &sa); /* pause */
|
|
/* Does not work as intended, at least in 2.6.20.
|
|
* SIGSTOP is simply ignored by init:
|
|
*/
|
|
sigaction_set(SIGSTOP, &sa); /* pause */
|
|
|
|
/* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
|
|
* setting handler without SA_RESTART flag.
|
|
*/
|
|
bb_signals_recursive_norestart((1 << SIGINT), record_signo);
|
|
}
|
|
|
|
/* Set up "reread /etc/inittab" handler.
|
|
* Handler is set up without SA_RESTART, it will interrupt syscalls.
|
|
*/
|
|
if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
|
|
bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
|
|
|
|
/* Now run everything that needs to be run */
|
|
/* First run the sysinit command */
|
|
run_actions(SYSINIT);
|
|
check_delayed_sigs();
|
|
/* Next run anything that wants to block */
|
|
run_actions(WAIT);
|
|
check_delayed_sigs();
|
|
/* Next run anything to be run only once */
|
|
run_actions(ONCE);
|
|
|
|
/* Now run the looping stuff for the rest of forever.
|
|
*/
|
|
while (1) {
|
|
int maybe_WNOHANG;
|
|
|
|
maybe_WNOHANG = check_delayed_sigs();
|
|
|
|
/* (Re)run the respawn/askfirst stuff */
|
|
run_actions(RESPAWN | ASKFIRST);
|
|
maybe_WNOHANG |= check_delayed_sigs();
|
|
|
|
/* Don't consume all CPU time - sleep a bit */
|
|
sleep(1);
|
|
maybe_WNOHANG |= check_delayed_sigs();
|
|
|
|
/* Wait for any child process(es) to exit.
|
|
*
|
|
* If check_delayed_sigs above reported that a signal
|
|
* was caught, wait will be nonblocking. This ensures
|
|
* that if SIGHUP has reloaded inittab, respawn and askfirst
|
|
* actions will not be delayed until next child death.
|
|
*/
|
|
if (maybe_WNOHANG)
|
|
maybe_WNOHANG = WNOHANG;
|
|
while (1) {
|
|
pid_t wpid;
|
|
struct init_action *a;
|
|
|
|
/* If signals happen _in_ the wait, they interrupt it,
|
|
* bb_signals_recursive_norestart set them up that way
|
|
*/
|
|
wpid = waitpid(-1, NULL, maybe_WNOHANG);
|
|
if (wpid <= 0)
|
|
break;
|
|
|
|
a = mark_terminated(wpid);
|
|
if (a) {
|
|
message(L_LOG, "process '%s' (pid %d) exited. "
|
|
"Scheduling for restart.",
|
|
a->command, wpid);
|
|
}
|
|
/* See if anyone else is waiting to be reaped */
|
|
maybe_WNOHANG = WNOHANG;
|
|
}
|
|
} /* while (1) */
|
|
}
|