xref: /base/startup/init/README.md

# init<a name="EN-US_TOPIC_0000001129033057"></a>

-   [Introduction](#section469617221261)
-   [Directory Structure](#section15884114210197)
-   [Constraints](#section12212842173518)
-   [Usage](#section837771600)
-   [Repositories Involved](#section641143415335)

## Introduction<a name="section469617221261"></a>

The init module starts system service processes from the time the kernel loads the first user-space process to the time the first application is started. In addition to loading key system processes, the module needs to configure their permissions during the startup and keep the specified process alive after sub-processes are started. If a process exits abnormally, the module needs to restart it, and to perform system reset for a special process.

## Directory Structure<a name="section15884114210197"></a>

```
base/startup/init/             # init module
├── LICENSE
└── services
    ├── include                  # Header files for the init module
    ├── src                      # Source files for the init module
    └── test                     # Source files of the test cases for the init module
        └── unittest
vendor
└──huawei
        └──camera
                └──init_configs  # init configuration files (in JSON format, and deployed in /etc/init.cfg after image burning)
```

## Constraints<a name="section12212842173518"></a>

Currently, the init module applies only to small-system devices \(reference memory ≥ 1 MB\), for example, Hi3516D V300 and Hi3518E V300.

## Usage<a name="section837771600"></a>

init divides the system startup into three phases:

pre-init: operations required before system services are started, for example, mounting a file system, creating a folder, and modifying permissions

init: operations required for starting system services.

post-init: operations required after system services are started.

In the  **init.cfg**  file, each of the preceding phases is represented by a job, which corresponds to a command set. The init\_lite module initializes the system by executing the commands in each job in sequence. Jobs are executed in the following sequence: pre-init \> init \> post-init. All jobs are stored in the  **jobs**  array in the  **init.cfg**  file.

In addition to the  **jobs**  array, the  **init.cfg**  file also provides a  **services**  array, which is used to store the names, executable file paths, permissions, and other attribute information of the key system services that need to be started by the init process.

The file is stored in  **/vendor/hisilicon/hispark\_aries/init\_configs/**  under  **/etc/**. It is in JSON format, and its size cannot exceed 100 KB.

The format and content of the  **init.cfg**  file are as follows:

```
{
    "jobs" : [{
            "name" : "pre-init",
            "cmds" : [
                "mkdir /testdir",
                "chmod 0700 /testdir",
                "chown 99 99 /testdir",
                "mkdir /testdir2",
                "mount vfat /dev/mmcblk0p0 /testdir2 noexec nosuid"
            ]
        }, {
            "name" : "init",
            "cmds" : [
                "start service1",
                "start service2"
             ]
        }, {
             "name" : "post-init",
             "cmds" : []
        }
    ],
    "services" : [{
            "name" : "service1",
            "path" : "/bin/process1",
            "uid" : 1,
            "gid" : 1,
            "secon" : "u:r:untrusted_app:s0",
            "once" : 0,
            "importance" : 1,
            "caps" : [0, 1, 2, 5]
    }, {
            "name" : "service2",
            "path" : "/bin/process2",
            "uid" : 2,
            "gid" : 2,
            "secon" : "u:r:untrusted_app:s0",
            "once" : 1,
            "importance" : 0,
            "caps" : []
        }
    ]
}
```

**Table  1**  Job description

<a name="table1801509284"></a>
<table><thead align="left"><tr id="row680703289"><th class="cellrowborder" valign="top" width="13.4%" id="mcps1.2.3.1.1"><p id="p11805012282"><a name="p11805012282"></a><a name="p11805012282"></a>Job Name</p>
</th>
<th class="cellrowborder" valign="top" width="86.6%" id="mcps1.2.3.1.2"><p id="p2811605289"><a name="p2811605289"></a><a name="p2811605289"></a>Description</p>
</th>
</tr>
</thead>
<tbody><tr id="row178140112810"><td class="cellrowborder" valign="top" width="13.4%" headers="mcps1.2.3.1.1 "><p id="p6811809281"><a name="p6811809281"></a><a name="p6811809281"></a>pre-init</p>
</td>
<td class="cellrowborder" valign="top" width="86.6%" headers="mcps1.2.3.1.2 "><p id="p18115019284"><a name="p18115019284"></a><a name="p18115019284"></a>Job that is executed first. Operations (for example, creating a folder) required before the process startup are executed in this job.</p>
</td>
</tr>
<tr id="row381120182817"><td class="cellrowborder" valign="top" width="13.4%" headers="mcps1.2.3.1.1 "><p id="p148116002812"><a name="p148116002812"></a><a name="p148116002812"></a>init</p>
</td>
<td class="cellrowborder" valign="top" width="86.6%" headers="mcps1.2.3.1.2 "><p id="p14818016288"><a name="p14818016288"></a><a name="p14818016288"></a>Job that is executed in between. Operations (for example, service startup) are executed in this job.</p>
</td>
</tr>
<tr id="row181100162813"><td class="cellrowborder" valign="top" width="13.4%" headers="mcps1.2.3.1.1 "><p id="p3811804281"><a name="p3811804281"></a><a name="p3811804281"></a>post-init</p>
</td>
<td class="cellrowborder" valign="top" width="86.6%" headers="mcps1.2.3.1.2 "><p id="p18116016285"><a name="p18116016285"></a><a name="p18116016285"></a>Job that is finally executed. Operations (for example, mounting the device after the driver initialization) required after the process startup are executed in this job.</p>
</td>
</tr>
</tbody>
</table>

A single job can hold a maximum of 30 commands \(only  **start**,  **mkdir**,  **chmod**,  **chown**,  **mount**, and  **loadcfg**  are supported currently\). The command name and parameters \(128 bytes or less\) must be separated by only one space.

**Table  2**  Commands supported by a job

<a name="table122681439144112"></a>
<table><thead align="left"><tr id="row826873984116"><th class="cellrowborder" valign="top" width="10.15%" id="mcps1.2.4.1.1"><p id="p826833919412"><a name="p826833919412"></a><a name="p826833919412"></a>Command</p>
</th>
<th class="cellrowborder" valign="top" width="34.089999999999996%" id="mcps1.2.4.1.2"><p id="p3381142134118"><a name="p3381142134118"></a><a name="p3381142134118"></a>Format and Example</p>
</th>
<th class="cellrowborder" valign="top" width="55.76%" id="mcps1.2.4.1.3"><p id="p1268539154110"><a name="p1268539154110"></a><a name="p1268539154110"></a>Description</p>
</th>
</tr>
</thead>
<tbody><tr id="row142681039124116"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p2083714604313"><a name="p2083714604313"></a><a name="p2083714604313"></a>mkdir</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p143811842154111"><a name="p143811842154111"></a><a name="p143811842154111"></a>mkdir <em id="i59061027135319"><a name="i59061027135319"></a><a name="i59061027135319"></a>target folder</em></p>
<p id="p4377174213435"><a name="p4377174213435"></a><a name="p4377174213435"></a>Example: mkdir /storage/myDirectory</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p56817536457"><a name="p56817536457"></a><a name="p56817536457"></a>Creates a folder. <strong id="b1111653719537"><a name="b1111653719537"></a><a name="b1111653719537"></a>mkdir</strong> and the target folder must be separated by only one space.</p>
</td>
</tr>
<tr id="row1268133919413"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p97961563461"><a name="p97961563461"></a><a name="p97961563461"></a>chmod</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p20381144234118"><a name="p20381144234118"></a><a name="p20381144234118"></a>chmod <em id="i15124416538"><a name="i15124416538"></a><a name="i15124416538"></a>permission</em> <em id="i1056644195314"><a name="i1056644195314"></a><a name="i1056644195314"></a>target</em></p>
<p id="p6334213124413"><a name="p6334213124413"></a><a name="p6334213124413"></a>Examples: chmod 0600 /storage/myFile.txt</p>
<p id="p1748214543444"><a name="p1748214543444"></a><a name="p1748214543444"></a>chmod 0750 /storage/myDir</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p2023822074614"><a name="p2023822074614"></a><a name="p2023822074614"></a>Modifies the permission, which must be in the <strong id="b8112193214139"><a name="b8112193214139"></a><a name="b8112193214139"></a>0<em id="i11455534181314"><a name="i11455534181314"></a><a name="i11455534181314"></a>xxx</em></strong> format. <strong id="b2675148175310"><a name="b2675148175310"></a><a name="b2675148175310"></a>chmod</strong>, <em id="i46798488538"><a name="i46798488538"></a><a name="i46798488538"></a>permission</em>, and <em id="i667944825318"><a name="i667944825318"></a><a name="i667944825318"></a>target</em> must be separated by only one space.</p>
</td>
</tr>
<tr id="row7268143918416"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p8255346174610"><a name="p8255346174610"></a><a name="p8255346174610"></a>chown</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p238114423418"><a name="p238114423418"></a><a name="p238114423418"></a>chown uid gid <em id="i161565145312"><a name="i161565145312"></a><a name="i161565145312"></a>target</em></p>
<p id="p1118592184518"><a name="p1118592184518"></a><a name="p1118592184518"></a>Example: chown 900 800 /storage/myDir</p>
<p id="p1235374884510"><a name="p1235374884510"></a><a name="p1235374884510"></a>chown 100 100 /storage/myFile.txt</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p18408185817467"><a name="p18408185817467"></a><a name="p18408185817467"></a>Modifies the owner group. <strong id="b19641958195310"><a name="b19641958195310"></a><a name="b19641958195310"></a>chown</strong>, <strong id="b15698584534"><a name="b15698584534"></a><a name="b15698584534"></a>uid</strong>, <strong id="b1692058135310"><a name="b1692058135310"></a><a name="b1692058135310"></a>gid</strong>, and <em id="i56935885316"><a name="i56935885316"></a><a name="i56935885316"></a>target</em> must be separated by only one space.</p>
</td>
</tr>
<tr id="row109751379478"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p1017823174717"><a name="p1017823174717"></a><a name="p1017823174717"></a>mount</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p10381124244117"><a name="p10381124244117"></a><a name="p10381124244117"></a>mount fileSystemType src dst flags data</p>
<p id="p572019493485"><a name="p572019493485"></a><a name="p572019493485"></a>Example: mount vfat /dev/mmcblk0 /sdc rw,umask=000</p>
<p id="p7381173625313"><a name="p7381173625313"></a><a name="p7381173625313"></a>mount jffs2 /dev/mtdblock3 /storage nosuid</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p11976107144710"><a name="p11976107144710"></a><a name="p11976107144710"></a>Mounts devices. Every two parameters must be separated by only one space. Currently, supported flags include <strong id="b5512525411"><a name="b5512525411"></a><a name="b5512525411"></a>nodev</strong>, <strong id="b41014514541"><a name="b41014514541"></a><a name="b41014514541"></a>noexec</strong>, <strong id="b5101152543"><a name="b5101152543"></a><a name="b5101152543"></a>nosuid</strong>, <strong id="b20103555419"><a name="b20103555419"></a><a name="b20103555419"></a>rdonly</strong>, and optionally <strong id="b41045175420"><a name="b41045175420"></a><a name="b41045175420"></a>data</strong>.</p>
</td>
</tr>
<tr id="row1334911198482"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p1214153117480"><a name="p1214153117480"></a><a name="p1214153117480"></a>start</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p133816420411"><a name="p133816420411"></a><a name="p133816420411"></a>start serviceName</p>
<p id="p2036714132541"><a name="p2036714132541"></a><a name="p2036714132541"></a>Example: start foundation</p>
<p id="p115951820185412"><a name="p115951820185412"></a><a name="p115951820185412"></a>start shell</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p4350121915488"><a name="p4350121915488"></a><a name="p4350121915488"></a>Starts services. <em id="i87951116544"><a name="i87951116544"></a><a name="i87951116544"></a>serviceName</em> must be contained in the <strong id="b379981145417"><a name="b379981145417"></a><a name="b379981145417"></a>services</strong> array.</p>
</td>
</tr>
<tr id="row96921442712"><td class="cellrowborder" valign="top" width="10.15%" headers="mcps1.2.4.1.1 "><p id="p1693642018"><a name="p1693642018"></a><a name="p1693642018"></a>loadcfg</p>
</td>
<td class="cellrowborder" valign="top" width="34.089999999999996%" headers="mcps1.2.4.1.2 "><p id="p1969364211116"><a name="p1969364211116"></a><a name="p1969364211116"></a>loadcfg filePath</p>
<p id="p1858112368211"><a name="p1858112368211"></a><a name="p1858112368211"></a>Example: loadcfg /patch/fstab.cfg</p>
</td>
<td class="cellrowborder" valign="top" width="55.76%" headers="mcps1.2.4.1.3 "><p id="p13986141320510"><a name="p13986141320510"></a><a name="p13986141320510"></a>Loads other <strong id="b280561515549"><a name="b280561515549"></a><a name="b280561515549"></a>.cfg</strong> files. The maximum size of the target file (only <strong id="b105471717135416"><a name="b105471717135416"></a><a name="b105471717135416"></a>/patch/fstab.cfg</strong> supported currently) is 50 KB. Each line in the <strong id="b14853122910540"><a name="b14853122910540"></a><a name="b14853122910540"></a>/patch/fstab.cfg</strong> file is a command. The command types and formats must comply with their respective requirements mentioned in this table. A maximum of 20 commands are allowed.</p>
</td>
</tr>
</tbody>
</table>

**Table  3**  Elements in the  **services**  array

<a name="table14737791471"></a>
<table><thead align="left"><tr id="row273839577"><th class="cellrowborder" valign="top" width="10.37%" id="mcps1.2.3.1.1"><p id="p107382095711"><a name="p107382095711"></a><a name="p107382095711"></a>Field</p>
</th>
<th class="cellrowborder" valign="top" width="89.63%" id="mcps1.2.3.1.2"><p id="p17738189277"><a name="p17738189277"></a><a name="p17738189277"></a>Description</p>
</th>
</tr>
</thead>
<tbody><tr id="row17386911716"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p17384912710"><a name="p17384912710"></a><a name="p17384912710"></a>name</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p1173818913714"><a name="p1173818913714"></a><a name="p1173818913714"></a>Name of the current service. The value cannot be empty and can contain a maximum of 32 bytes.</p>
</td>
</tr>
<tr id="row1473810916714"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p127381991571"><a name="p127381991571"></a><a name="p127381991571"></a>path</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p1073815910717"><a name="p1073815910717"></a><a name="p1073815910717"></a>Full path (including parameters) of the executable file for the current service. This is an array. Ensure that the first element is the path of the executable file, the maximum number of elements is 20, and each element is a string that contains a maximum of 64 bytes.</p>
</td>
</tr>
<tr id="row77381291271"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p77381391770"><a name="p77381391770"></a><a name="p77381391770"></a>uid</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p107387920711"><a name="p107387920711"></a><a name="p107387920711"></a>User ID (UID) of the current service process.</p>
</td>
</tr>
<tr id="row127381591673"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p47388919715"><a name="p47388919715"></a><a name="p47388919715"></a>gid</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p12738691479"><a name="p12738691479"></a><a name="p12738691479"></a>Group ID (GID) of the current service process.</p>
</td>
</tr>
<tr id="row127381591693"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p47388919793"><a name="p47388919793"></a><a name="p47388919715"></a>secon</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p12738691493"><a name="p12738691493"></a><a name="p12738691493"></a>Security context of the current service process (no need to set currently).</p>
</td>
</tr>
<tr id="row188301014171116"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p183112146115"><a name="p183112146115"></a><a name="p183112146115"></a>once</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p18548317195715"><a name="p18548317195715"></a><a name="p18548317195715"></a>Whether the current service process is a one-off process.</p>
<p id="p103571840105812"><a name="p103571840105812"></a><a name="p103571840105812"></a><strong id="b7898115614817"><a name="b7898115614817"></a><a name="b7898115614817"></a>1</strong>: The current service process is a one-off process. If the process exits, the init process does not restart it.</p>
<p id="p5831191431116"><a name="p5831191431116"></a><a name="p5831191431116"></a><strong id="b20971155820811"><a name="b20971155820811"></a><a name="b20971155820811"></a>0</strong>: The current service process is not a one-off process. If the process exits, the init process restarts it upon receiving the SIGCHLD signal.</p>
<p id="p378912714010"><a name="p378912714010"></a><a name="p378912714010"></a>Note: If a non-one-off process exits for five consecutive times within four minutes, the init process will no longer restart it at the fifth exit.</p>
</td>
</tr>
<tr id="row386110321155"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p14861113212156"><a name="p14861113212156"></a><a name="p14861113212156"></a>importance</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p166448210816"><a name="p166448210816"></a><a name="p166448210816"></a>Whether the current service process is a key system process.</p>
<p id="p8572182712811"><a name="p8572182712811"></a><a name="p8572182712811"></a><strong id="b72917915010"><a name="b72917915010"></a><a name="b72917915010"></a>0</strong>: The current service process is not a key system process. If it exits, the init process does not reset or restart the system.</p>
<p id="p11861032111516"><a name="p11861032111516"></a><a name="p11861032111516"></a><strong id="b1074320101309"><a name="b1074320101309"></a><a name="b1074320101309"></a>1</strong>: The current service process is a key system process. If it exits, the init process resets and restarts the system.</p>
</td>
</tr>
<tr id="row1689310618179"><td class="cellrowborder" valign="top" width="10.37%" headers="mcps1.2.3.1.1 "><p id="p108931367177"><a name="p108931367177"></a><a name="p108931367177"></a>caps</p>
</td>
<td class="cellrowborder" valign="top" width="89.63%" headers="mcps1.2.3.1.2 "><p id="p489313618173"><a name="p489313618173"></a><a name="p489313618173"></a>Capabilities required by the current service. They are evaluated based on the capabilities supported by the security subsystem and configured in accordance with the principle of least permission. Currently, a maximum of 100 values can be configured.</p>
</td>
</tr>
</tbody>
</table>

## Repositories Involved<a name="section641143415335"></a>

[Startup subsystem](https://gitee.com/openharmony/docs/blob/master/en/readme/startup.md)

[startup\_syspara\_lite](https://gitee.com/openharmony/startup_syspara_lite/blob/master/README.md)

[startup\_appspawn\_lite](https://gitee.com/openharmony/startup_appspawn_lite/blob/master/README.md)

[startup\_bootstrap\_lite](https://gitee.com/openharmony/startup_bootstrap_lite/blob/master/README.md)

**[startup\_init\_lite]**