290 lines
7.7 KiB
Text
290 lines
7.7 KiB
Text
|
|
Android Init Language
|
|
---------------------
|
|
|
|
The Android Init Language consists of four broad classes of statements,
|
|
which are Actions, Commands, Services, and Options.
|
|
|
|
All of these are line-oriented, consisting of tokens separated by
|
|
whitespace. The c-style backslash escapes may be used to insert
|
|
whitespace into a token. Double quotes may also be used to prevent
|
|
whitespace from breaking text into multiple tokens. The backslash,
|
|
when it is the last character on a line, may be used for line-folding.
|
|
|
|
Lines which start with a # (leading whitespace allowed) are comments.
|
|
|
|
Actions and Services implicitly declare a new section. All commands
|
|
or options belong to the section most recently declared. Commands
|
|
or options before the first section are ignored.
|
|
|
|
Actions and Services have unique names. If a second Action or Service
|
|
is declared with the same name as an existing one, it is ignored as
|
|
an error. (??? should we override instead)
|
|
|
|
|
|
Actions
|
|
-------
|
|
Actions are named sequences of commands. Actions have a trigger which
|
|
is used to determine when the action should occur. When an event
|
|
occurs which matches an action's trigger, that action is added to
|
|
the tail of a to-be-executed queue (unless it is already on the
|
|
queue).
|
|
|
|
Each action in the queue is dequeued in sequence and each command in
|
|
that action is executed in sequence. Init handles other activities
|
|
(device creation/destruction, property setting, process restarting)
|
|
"between" the execution of the commands in activities.
|
|
|
|
Actions take the form of:
|
|
|
|
on <trigger>
|
|
<command>
|
|
<command>
|
|
<command>
|
|
|
|
|
|
Services
|
|
--------
|
|
Services are programs which init launches and (optionally) restarts
|
|
when they exit. Services take the form of:
|
|
|
|
service <name> <pathname> [ <argument> ]*
|
|
<option>
|
|
<option>
|
|
...
|
|
|
|
|
|
Options
|
|
-------
|
|
Options are modifiers to services. They affect how and when init
|
|
runs the service.
|
|
|
|
critical
|
|
This is a device-critical service. If it exits more than four times in
|
|
four minutes, the device will reboot into recovery mode.
|
|
|
|
disabled
|
|
This service will not automatically start with its class.
|
|
It must be explicitly started by name.
|
|
|
|
setenv <name> <value>
|
|
Set the environment variable <name> to <value> in the launched process.
|
|
|
|
socket <name> <type> <perm> [ <user> [ <group> ] ]
|
|
Create a unix domain socket named /dev/socket/<name> and pass
|
|
its fd to the launched process. <type> must be "dgram" or "stream".
|
|
User and group default to 0.
|
|
|
|
user <username>
|
|
Change to username before exec'ing this service.
|
|
Currently defaults to root. (??? probably should default to nobody)
|
|
Currently, if your process requires linux capabilities then you cannot use
|
|
this command. You must instead request the capabilities in-process while
|
|
still root, and then drop to your desired uid.
|
|
|
|
group <groupname> [ <groupname> ]*
|
|
Change to groupname before exec'ing this service. Additional
|
|
groupnames beyond the (required) first one are used to set the
|
|
supplemental groups of the process (via setgroups()).
|
|
Currently defaults to root. (??? probably should default to nobody)
|
|
|
|
oneshot
|
|
Do not restart the service when it exits.
|
|
|
|
class <name>
|
|
Specify a class name for the service. All services in a
|
|
named class may be started or stopped together. A service
|
|
is in the class "default" if one is not specified via the
|
|
class option.
|
|
|
|
onrestart
|
|
Execute a Command (see below) when service restarts.
|
|
|
|
Triggers
|
|
--------
|
|
Triggers are strings which can be used to match certain kinds
|
|
of events and used to cause an action to occur.
|
|
|
|
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.
|
|
|
|
|
|
Commands
|
|
--------
|
|
|
|
exec <path> [ <argument> ]*
|
|
Fork and execute a program (<path>). This will block until
|
|
the program completes execution. It is best to avoid exec
|
|
as unlike the builtin commands, it runs the risk of getting
|
|
init "stuck". (??? maybe there should be a timeout?)
|
|
|
|
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.
|
|
|
|
chmod <octal-mode> <path>
|
|
Change file access permissions.
|
|
|
|
chown <owner> <group> <path>
|
|
Change file owner and group.
|
|
|
|
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> [mode] [owner] [group]
|
|
Create a directory at <path>, optionally with the given mode, owner, and
|
|
group. If not provided, the directory is created with permissions 755 and
|
|
owned by the root user and root group.
|
|
|
|
mount <type> <device> <dir> [ <mountoption> ]*
|
|
Attempt to mount the named device at the directory <dir>
|
|
<device> may be of the form mtd@name to specify a mtd block
|
|
device by name.
|
|
<mountoption>s include "ro", "rw", "remount", "noatime", ...
|
|
|
|
setkey
|
|
TBD
|
|
|
|
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>
|
|
|
|
trigger <event>
|
|
Trigger an event. Used to queue an action from another
|
|
action.
|
|
|
|
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:
|
|
|
|
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", "restarting")
|
|
|
|
|
|
Example init.conf
|
|
-----------------
|
|
|
|
# not complete -- just providing some examples of usage
|
|
#
|
|
on boot
|
|
export PATH /sbin:/system/sbin:/system/bin
|
|
export LD_LIBRARY_PATH /system/lib
|
|
|
|
mkdir /dev
|
|
mkdir /proc
|
|
mkdir /sys
|
|
|
|
mount tmpfs tmpfs /dev
|
|
mkdir /dev/pts
|
|
mkdir /dev/socket
|
|
mount devpts devpts /dev/pts
|
|
mount proc proc /proc
|
|
mount sysfs sysfs /sys
|
|
|
|
write /proc/cpu/alignment 4
|
|
|
|
ifup lo
|
|
|
|
hostname localhost
|
|
domainname localhost
|
|
|
|
mount yaffs2 mtd@system /system
|
|
mount yaffs2 mtd@userdata /data
|
|
|
|
import /system/etc/init.conf
|
|
|
|
class_start default
|
|
|
|
service adbd /sbin/adbd
|
|
user adb
|
|
group adb
|
|
|
|
service usbd /system/bin/usbd -r
|
|
user usbd
|
|
group usbd
|
|
socket usbd 666
|
|
|
|
service zygote /system/bin/app_process -Xzygote /system/bin --zygote
|
|
socket zygote 666
|
|
|
|
service runtime /system/bin/runtime
|
|
user system
|
|
group system
|
|
|
|
on device-added-/dev/compass
|
|
start akmd
|
|
|
|
on device-removed-/dev/compass
|
|
stop akmd
|
|
|
|
service akmd /sbin/akmd
|
|
disabled
|
|
user akmd
|
|
group akmd
|
|
|
|
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
|