android init.rc 语法分析

此文来自于对http://source.android.com/porting/index.html中bring up段的简译。其中有一处与源码的

system/core/init/readme.txt（此文也是对init.rc 的解释）内容不同：

socket <name> <type> <perm> [ <user> [ <group> ] ]

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注1：另外还讲述了怎样输出log：

Debugging notes
---------------
By default, programs executed by init will drop stdout and stderr into
/dev/null. To help with debugging, you can execute your program via the
Andoird program logwrapper. This will redirect stdout/stderr into the
Android logging system (accessed via logcat).
For example
service akmd /system/bin/logwrapper /sbin/akmd

注2：讲述了一个新的命令

sysclktz <mins_west_of_gmt>
   Set the system clock base (0 if system clock ticks in GMT)

注3：triggers

boot
   This is the first trigger that will occur when init starts
   (after /init.conf is loaded)
<name>=<value>
   Triggers of this form occur when the property <name> is set
   to the specific value <value>.
device-added-<path>
device-removed-<path>
   Triggers of these forms occur when a device node is added
   or removed.
service-exited-<name>
   Triggers of this form occur when the specified service exits.

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init 由如下四种类型语句组成：

• Actionn       ：行为
• Commands
• Services
• Options

语法(language syntax)结构如下：

• 每一个语句占据一行，并且各个关键字被空格分开。c规范中的（如 \n）反斜杠将被忽略(backslash escapes)而被认为是一个空格 ，双引号用来保证空格不会把一个文字串分分为多个关键字。行最后的反斜杠用作续行。
• 由 # （前面允许有空格）开始的行都是注释行(comment)
• 一个actions 或 services 的开始隐含声明了一个新的段，所有commands 或 options 属于最近的声明。在第一个段之前的 commands 或 options 都会被忽略
• 每一个actions 和 services 都有不同的名字。后面与前面发生重名的，那么这个后面重名的将被忽略或被认为是一个错误

Actions

Actions其实就是一组被命名的命令序列。actions 都有一个触发条件，触发条件决定了action何时执行。当一个事件发生如果匹配action的触发条件，那么这个action将会被添加到预备执行队列的尾部（除非它已经在队列当中）

每一个action中的命令将被顺序执行。init进程负责在其它activities（如：设备创建/销毁，属性设置，进程重启）之间执行这些命令序列。

action 的格式如下

on <trigger>
  <command>
  <command>
  <command>

Services

services 是一些由init 启动 和 重新（如果有需要）启动的程序，当然这些程序如果是存在的。

services 的格式如下：

  service <name> <pathname> [ <argument> ]*
  <option>
  <option>
  ... 

Options

options 是service的修饰符，用来告诉init 怎样及何时启动service。

Option	Description
disabled	This service will not automatically start with its class. It must be explicitly started by name.
socket <type> <name> <perm> [ <user> [ <group> ] ]	Create a unix domain socket named /dev/socket/<name> and pass its fd to the launched process. Valid <type>dgram and stream. user and group default to 0.(type 实际中是放在name之后) values include
user <username>	Change to username before exec'ing this service. Currently defaults to root.
group <groupname> [ <groupname> ]*	Change to groupname before exec'ing this service.  Additional  groupnames beyond the first, which is required, are used to set additional groups of the process (withsetgroups()). Currently defaults to root.
capability [ <capability> ]+	Set linux capability before exec'ing this service
oneshot	Do not restart the service when it exits.
class <name>	Specify a class name for the service.  All services in a named class must start and stop together. A service is considered of class "default" if one is not specified via the class option.

Triggers

Triggers are strings used to match certain kinds of events that cause an action to occur.

Trigger	Description
boot	This is the first trigger that occurs when init starts (after /init.conf is loaded).
<name>=<value>	Triggers of this form occur when the property <name> is set to the specific value<value>.
device-added-<path> device-removed-<path>	Triggers of these forms occur when a device node is added or removed.
service-exited-<name>	Triggers of this form occur when the specified service exits.

Commands

Command	Description
exec <path> [ <argument> ]*	Fork and execute a program (<path>). This will block until the program completes execution. Try to avoid exec. Unlike the builtin commands, it runs the risk of getting init "stuck".
export <name> <value>	Set the environment variable <name> equal to <value> in the global environment (which will be inherited by all processes started after this command is executed).
ifup <interface>	Bring the network interface <interface> online.
import <filename>	Parse an init config file, extending the current configuration.
hostname <name>	Set the host name.
class_start <serviceclass>	Start all services of the specified class if they are not already running.
class_stop <serviceclass>	Stop all services of the specified class if they are currently running.
domainname <name>	Set the domain name.
insmod <path>	Install the module at <path>.
mkdir <path>	Make a directory at <path>.
mount <type> <device> <dir> [ <mountoption> ]*	Attempt to mount the named device at the directory <dir> <device>. This may be of the form mtd@name to specify a mtd block device by name.
setkey	- currenlty undefined -
setprop <name> <value>	Set system property <name> to <value>.
setrlimit <resource> <cur> <max>	Set the rlimit for a resource.
start <service>	Start a service running if it is not already running.
stop <service>	Stop a service from running if it is currently running.
symlink <target> <path>	Create a symbolic link at <path> with the value <target>.
write <path> <string> [ <string> ]*	Open the file at <path> and write one or more strings to it with write(2).

Properties

Init updates some system properties to provide some insight into 
what it's doing:

Property	Description
init.action	Equal to the name of the action currently being executed or "" if none.
init.command	Equal to the command being executed or "" if none.
init.svc.<name>	State of a named service ("stopped", "running", or "restarting").

在init.rc中使用属性的范例如下：

setprop ro.FOREGROUND_APP_MEM 1536

setprop ro.VISIBLE_APP_MEM 2048

on property:ro.kernel.qemu=1

start adbd

setprop用于设置属性，on property可以用于判断属性，这里的属性在整个Android系统运行中都是一致的。

init脚本中的关键字可以参考：system/core/init/keywords.h

exam init.rc

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on init

sysclktz 0

loglevel 3

# setup the global environment
    export PATH /sbin:/system/sbin:/system/bin:/system/xbin:/system/busybox/bin:/system/busybox/sbin:/system/busybox/usr/bin:/system/busybox/usr/sbin
    export LD_LIBRARY_PATH /system/lib
    export ANDROID_BOOTLOGO 1
    export ANDROID_ROOT /system
    export ANDROID_ASSETS /system/app
    export ANDROID_DATA /data
    export EXTERNAL_STORAGE /sdcard
    export BOOTCLASSPATH /system/framework/core.jar:/system/framework/ext.jar:/system/framework/framework.jar:/system/framework/android.policy.jar:/system/framework/services.jar

# Backward compatibility
    symlink /system/etc /etc
    symlink /sys/kernel/debug /d

# create mountpoints and mount tmpfs on sqlite_stmt_journals
    mkdir /sdcard 0000 system system
    mkdir /system
    mkdir /data 0771 system system
    mkdir /cache 0770 system cache
    mkdir /config 0500 root root
    mkdir /sqlite_stmt_journals 01777 root root
    mount tmpfs tmpfs /sqlite_stmt_journals size=4m

#{{ added by FriendlyARM
    mkdir /udisk  0000 system system
    mkdir /var 0000 system system
    mount tmpfs tmpfs  /var size=2m
    mkdir /var/lock
    mkdir /var/run
    mkdir /var/log
    mount usbfs none /proc/bus/usb -o devmode=0666
    chmod 0666 /dev/backlight-1wire
#}}

##  mount rootfs rootfs / ro remount

write /proc/sys/kernel/panic_on_oops 1
    write /proc/sys/kernel/hung_task_timeout_secs 0
    write /proc/cpu/alignment 4
    write /proc/sys/kernel/sched_latency_ns 10000000
    write /proc/sys/kernel/sched_wakeup_granularity_ns 2000000
    write /proc/sys/kernel/sched_compat_yield 1
    write /proc/sys/kernel/sched_child_runs_first 0

# Create cgroup mount points for process groups
    mkdir /dev/cpuctl
    mount cgroup none /dev/cpuctl cpu
    chown system system /dev/cpuctl
    chown system system /dev/cpuctl/tasks
    chmod 0777 /dev/cpuctl/tasks
    write /dev/cpuctl/cpu.shares 1024

mkdir /dev/cpuctl/fg_boost
    chown system system /dev/cpuctl/fg_boost/tasks
    chmod 0777 /dev/cpuctl/fg_boost/tasks
    write /dev/cpuctl/fg_boost/cpu.shares 1024

mkdir /dev/cpuctl/bg_non_interactive
    chown system system /dev/cpuctl/bg_non_interactive/tasks
    chmod 0777 /dev/cpuctl/bg_non_interactive/tasks
    # 5.0 %
    write /dev/cpuctl/bg_non_interactive/cpu.shares 52

# mount mtd partitions
    # Mount /system rw first to give the filesystem a chance to save a checkpoint
##    mount yaffs2 mtd@system /system
##    mount yaffs2 mtd@system /system ro remount

# We chown/chmod /data again so because mount is run as root + defaults
##    mount yaffs2 mtd@userdata /data nosuid nodev
    chown system system /data
    chmod 0771 /data

# Create dump dir and collect dumps.
    # Do this before we mount cache so eventually we can use cache for
    # storing dumps on platforms which do not have a dedicated dump partition.
   
    mkdir /data/dontpanic
    chown root log /data/dontpanic
    chmod 0750 /data/dontpanic

# Collect apanic data, free resources and re-arm trigger
    copy /proc/apanic_console /data/dontpanic/apanic_console
    chown root log /data/dontpanic/apanic_console
    chmod 0640 /data/dontpanic/apanic_console

copy /proc/apanic_threads /data/dontpanic/apanic_threads
    chown root log /data/dontpanic/apanic_threads
    chmod 0640 /data/dontpanic/apanic_threads

write /proc/apanic_console 1

# Collect ramconsole data
    copy /proc/last_kmsg /data/dontpanic/last_kmsg
    chown root log /data/dontpanic/last_kmsg
    chmod 0640 /data/dontpanic/last_kmsg

# Same reason as /data above
##    mount yaffs2 mtd@cache /cache nosuid nodev
    chown system cache /cache
    chmod 0770 /cache

# This may have been created by the recovery system with odd permissions
    chown system system /cache/recovery
    chmod 0770 /cache/recovery

#change permissions on vmallocinfo so we can grab it from bugreports
    chown root log /proc/vmallocinfo
    chmod 0440 /proc/vmallocinfo

# create basic filesystem structure
    mkdir /data/misc 01777 system misc
    mkdir /data/misc/bluetoothd 0777 bluetooth bluetooth
    mkdir /data/misc/keystore 0700 keystore keystore
    mkdir /data/misc/vpn 0770 system system
    mkdir /data/misc/vpn/profiles 0770 system system
    mkdir /data/misc/wifi 0777 wifi wifi
    mkdir /data/misc/wifi/sockets 0777 system wifi
    chmod 0777 /data/misc/wifi
    chmod 0777 /data/misc/wifi/wpa_supplicant.conf
    # give system access to wpa_supplicant.conf for backup and restore
    chmod 0777 /system/etc/wifi/wpa_supplicant.conf
    mkdir /data/misc/dhcp 0770 dhcp dhcp
    chown dhcp dhcp /data/misc/dhcp
    mkdir /data/local 0771 shell shell
    mkdir /data/local/tmp 0771 shell shell
    mkdir /data/data 0771 system system
    mkdir /data/app-private 0771 system system
    mkdir /data/app 0771 system system
    mkdir /data/property 0700 root root

# create dalvik-cache and double-check the perms
    mkdir /data/dalvik-cache 0771 system system
    chown system system /data/dalvik-cache
    chmod 0771 /data/dalvik-cache

# create the lost+found directories, so as to enforce our permissions
    mkdir /data/lost+found 0770
    mkdir /cache/lost+found 0770

# double check the perms, in case lost+found already exists, and set owner
    chown root root /data/lost+found
    chmod 0770 /data/lost+found
    chown root root /cache/lost+found
    chmod 0770 /cache/lost+found

#===================================================================
    #
    # debug fs enable for wifi & bluetooth
    #
    #===================================================================
    mount debugfs none /sys/kernel/debug

on boot
# basic network init
    ifup lo
    ifup eth0
    ifup eth1
    hostname localhost
    domainname localdomain

# set RLIMIT_NICE to allow priorities from 19 to -20
    setrlimit 13 40 40

# Define the oom_adj values for the classes of processes that can be
# killed by the kernel.  These are used in ActivityManagerService.
    setprop ro.FOREGROUND_APP_ADJ 0
    setprop ro.VISIBLE_APP_ADJ 1
    setprop ro.SECONDARY_SERVER_ADJ 2
    setprop ro.BACKUP_APP_ADJ 2
    setprop ro.HOME_APP_ADJ 4
    setprop ro.HIDDEN_APP_MIN_ADJ 7
    setprop ro.CONTENT_PROVIDER_ADJ 14
    setprop ro.EMPTY_APP_ADJ 15

# Define the memory thresholds at which the above process classes will
# be killed.  These numbers are in pages (4k).
    setprop ro.FOREGROUND_APP_MEM 1536
    setprop ro.VISIBLE_APP_MEM 2048
    setprop ro.SECONDARY_SERVER_MEM 4096
    setprop ro.BACKUP_APP_MEM 4096
    setprop ro.HOME_APP_MEM 4096
    setprop ro.HIDDEN_APP_MEM 5120
    setprop ro.CONTENT_PROVIDER_MEM 5632
    setprop ro.EMPTY_APP_MEM 6144

#Wifi
#    insmod /system/lib/libwifi/lib80211.ko 
#    insmod /system/lib/libwifi/lib80211_crypt_ccmp.ko
#    insmod /system/lib/libwifi/lib80211_crypt_tkip.ko
#    insmod /system/lib/libwifi/lib80211_crypt_wep.ko
#    insmod /system/lib/modules/2.6.27/kernel/net/bluetooth/bluetooth.ko
#    insmod /system/lib/modules/2.6.27/kernel/drivers/bluetooth/hci_uart.ko
#    insmod /system/lib/modules/2.6.27/kernel/net/bluetooth/l2cap.ko
#    insmod /system/lib/modules/2.6.27/kernel/net/bluetooth/rfcomm/rfcomm.ko
    
    setprop wifi.interface eth1
    setprop wlan.interface eth1
    setprop wlan.driver.status ok
    setprop wlan.modpath /system/lib/libwifi/ 
    setprop wlan.mod1 libertas.ko 
    setprop wlan.mod2 libertas_sdio.ko 
# Write value must be consistent with the above properties.
# Note that the driver only supports 6 slots, so we have HOME_APP at the
# same memory level as services.
    write /sys/module/lowmemorykiller/parameters/adj 0,1,2,7,14,15

write /proc/sys/vm/overcommit_memory 1
    write /proc/sys/vm/min_free_order_shift 4
    write /sys/module/lowmemorykiller/parameters/minfree 1536,2048,4096,5120,5632,6144

# Set init its forked children's oom_adj.
    write /proc/1/oom_adj -16

# Tweak background writeout
    write /proc/sys/vm/dirty_expire_centisecs 200
    write /proc/sys/vm/dirty_background_ratio  5

# Permissions for System Server and daemons.
    chown radio system /sys/android_power/state
    chown radio system /sys/android_power/request_state
    chown radio system /sys/android_power/acquire_full_wake_lock
    chown radio system /sys/android_power/acquire_partial_wake_lock
    chown radio system /sys/android_power/release_wake_lock
    chown radio system /sys/power/state
    chown radio system /sys/power/wake_lock
    chown radio system /sys/power/wake_unlock
    chmod 0660 /sys/power/state
    chmod 0660 /sys/power/wake_lock
    chmod 0660 /sys/power/wake_unlock
    chown system system /sys/class/timed_output/vibrator/enable
    chown system system /sys/class/leds/keyboard-backlight/brightness
#    chown system system /sys/class/leds/lcd-backlight/brightness
    chown system system /sys/class/backlight/pwm-backlight/brightness
    chown system system /sys/class/leds/button-backlight/brightness
    chown system system /sys/class/leds/jogball-backlight/brightness
    chown system system /sys/class/leds/red/brightness
    chown system system /sys/class/leds/green/brightness
    chown system system /sys/class/leds/blue/brightness
    chown system system /sys/class/leds/red/device/grpfreq
    chown system system /sys/class/leds/red/device/grppwm
    chown system system /sys/class/leds/red/device/blink
    chown system system /sys/class/leds/red/brightness
    chown system system /sys/class/leds/green/brightness
    chown system system /sys/class/leds/blue/brightness
    chown system system /sys/class/leds/red/device/grpfreq
    chown system system /sys/class/leds/red/device/grppwm
    chown system system /sys/class/leds/red/device/blink
    chown system system /sys/class/timed_output/vibrator/enable
    chown system system /sys/module/sco/parameters/disable_esco
    chown system system /sys/kernel/ipv4/tcp_wmem_min
    chown system system /sys/kernel/ipv4/tcp_wmem_def
    chown system system /sys/kernel/ipv4/tcp_wmem_max
    chown system system /sys/kernel/ipv4/tcp_rmem_min
    chown system system /sys/kernel/ipv4/tcp_rmem_def
    chown system system /sys/kernel/ipv4/tcp_rmem_max
    chown root radio /proc/cmdline
    #bluetooth power up/down interface
#    chown bluetooth bluetooth /sys/class/rfkill/rfkill0/type
#    chown bluetooth bluetooth /sys/class/rfkill/rfkill0/state
#    chmod 0660                /sys/class/rfkill/rfkill0/state
#    chown bluetooth bluetooth /dev/s3c2410_serial1
    chmod 0666    /dev/s3c2410_serial1
    chmod 0666    /dev/s3c2410_serial2
    chmod 0666    /dev/s3c2410_serial3
    chmod 0666    /dev/video0
    chmod 0666    /dev/s3c-jpg

# Define TCP buffer sizes for various networks
#   ReadMin, ReadInitial, ReadMax, WriteMin, WriteInitial, WriteMax,
    setprop net.tcp.buffersize.default 4096,87380,110208,4096,16384,110208
    setprop net.tcp.buffersize.wifi    4095,87380,110208,4096,16384,110208
    setprop net.tcp.buffersize.umts    4094,87380,110208,4096,16384,110208
    setprop net.tcp.buffersize.edge    4093,26280,35040,4096,16384,35040
    setprop net.tcp.buffersize.gprs    4092,8760,11680,4096,8760,11680
    setprop net.dns1 8.8.8.8 
    setprop net.dns2 8.8.4.4

class_start default
    setprop alsa.mixer.playback.master Front 
    setprop alsa.mixer.capture.master Capture 
    setprop alsa.mixer.playback.earpiece Master 
    setprop alsa.mixer.capture.earpiece Capture 
    setprop alsa.mixer.playback.headset Master 
    setprop alsa.mixer.playback.speaker Master

## Daemon processes to be run by init.
##
service console /system/bin/sh
#service console /system/busybox/bin/ash
    console

# adbd is controlled by the persist.service.adb.enable system property
service adbd /sbin/adbd
    disabled

# adbd on at boot in emulator
on property:ro.kernel.qemu=1
    start adbd

on property:persist.service.adb.enable=1
    start adbd

on property:persist.service.adb.enable=0
    stop adbd

service servicemanager /system/bin/servicemanager
    user system
    critical
    onrestart restart zygote
    onrestart restart media

service vold /system/bin/vold
    socket vold stream 0660 root mount

service tsd /sbin/tsd

service nexus /system/bin/nexus
    socket nexus stream 0660 root system
    disabled

#service mountd /system/bin/mountd
#    socket mountd stream 0660 root mount

service debuggerd /system/bin/debuggerd

service udiskd /system/bin/udiskd
    socket udiskd stream 666 root mount

service fanetworkservice /system/bin/fa-network-service
    socket fa-network-service stream 666 radio radio
    user root 
    group radio cache inet misc audio

#user radio 
#group radio cache inet misc audio

service ril-daemon /system/bin/rild -l /system/lib/libreference-ril.so -- -d /dev/pts/0
    socket rild stream 660 root radio
    socket rild-debug stream 660 radio system
    user root
    group radio cache inet misc audio

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server
    socket zygote stream 666
    onrestart write /sys/android_power/request_state wake
    onrestart write /sys/power/state on
    onrestart restart media

service media /system/bin/mediaserver
    user media
    group system audio camera graphics inet net_bt net_bt_admin

##service bootsound /system/bin/playmp3
##    user media
##    group audio
##    oneshot

service bootanim /system/bin/bootanimation
    user graphics
    group graphics
    disabled
    oneshot

service dbus /system/bin/dbus-daemon --system --nofork
    socket dbus stream 660 bluetooth bluetooth
    user bluetooth
    group bluetooth net_bt_admin

service wpa_supplicant /system/bin/logwrapper /system/bin/wpa_supplicant -Dwext -ieth1 -c /system/etc/wifi/wpa_supplicant.conf -dd
    group system wifi inet keystore
    disabled
    oneshot

service dhcpcd /system/bin/logwrapper /system/bin/dhcpcd -d eth1
    disabled
    oneshot
    group system dhcp

on property:init.svc.wpa_supplicant=stopped
    stop dhcpcd

service bluetoothd /system/bin/logwrapper /system/bin/bluetoothd -d -n 
    socket bluetooth stream 660 bluetooth bluetooth
    socket dbus_bluetooth stream 660 bluetooth bluetooth
    # init.rc does not yet support applying capabilities, so run as root and
    # let bluetoothd drop uid to bluetooth with the right linux capabilities
    group bluetooth net_bt_admin misc
    disabled

# baudrate change 115200 to 1152000(Bluetooth)
service changebaudrate /system/bin/logwrapper /system/xbin/bccmd_115200 -t bcsp -d /dev/s3c2410_serial1 psset -r 0x1be 0x126e
    user bluetooth
    group bluetooth net_bt_admin
    disabled
    oneshot

#service hciattach /system/bin/logwrapper /system/bin/hciattach -n -s 1152000 /dev/s3c2410_serial1 bcsp 1152000
service hciattach /system/bin/logwrapper /system/bin/hciattach -n -s 115200 /dev/s3c2410_serial1 bcsp 115200
    user bluetooth
    group bluetooth net_bt_admin misc
    disabled

service hfag /system/bin/sdptool add --channel=10 HFAG
    user bluetooth
    group bluetooth net_bt_admin
    disabled
    oneshot

service hsag /system/bin/sdptool add --channel=11 HSAG
    user bluetooth
    group bluetooth net_bt_admin
    disabled
    oneshot

service opush /system/bin/sdptool add --channel=12 OPUSH
    user bluetooth
    group bluetooth net_bt_admin
    disabled
    oneshot

service pbap /system/bin/sdptool add --channel=19 PBAP
    user bluetooth
    group bluetooth net_bt_admin
    disabled
    oneshot

service installd /system/bin/installd
    socket installd stream 600 system system

##service flash_recovery /system/etc/install-recovery.sh
##    oneshot

service racoon /system/bin/racoon
    socket racoon stream 600 system system
    # racoon will setuid to vpn after getting necessary resources.
    group net_admin
    disabled
    oneshot

service mtpd /system/bin/mtpd
    socket mtpd stream 600 system system
    user vpn
    group vpn net_admin net_raw
    disabled
    oneshot

service keystore /system/bin/keystore /data/misc/keystore
    user keystore
    group keystore
    socket keystore stream 666

service dumpstate /system/bin/dumpstate -s
    socket dumpstate stream 0660 shell log
    disabled
    oneshot