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2021-09-22 21:52:48 +08:00
# Utils<a name="EN-US_TOPIC_0000001121139825"></a>
- [Overview](#section62661387114)
- [Directory Structure](#section1464106163817)
- [Usage](#section25021123178)
- [Repositories Involved](#section4571352889)
## Overview<a name="section62661387114"></a>
The Utils repository stores basic components of OpenHarmony. These basic components are used by OpenHarmony subsystems and upper-layer applications.
The Utils library provides the following capabilities on different platforms:
- LiteOS Cortex-M \(Hi3861 platform\): key value \(KV\) store, file operations, timer, and system attribute dumping
- LiteOS Cortex-A \(Hi3516 or Hi3518 platform\): KV store, timer, JavaScript APIs for device query and data storage, and system attribute dumping
**Table 1** Utils capabilities
<a name="en-us_topic_0000001052623010_table206292206282"></a>
<table><thead align="left"><tr id="en-us_topic_0000001052623010_row8629020112819"><th class="cellrowborder" valign="top" width="21.22%" id="mcps1.2.4.1.1"><p id="en-us_topic_0000001052623010_p66291220192816"><a name="en-us_topic_0000001052623010_p66291220192816"></a><a name="en-us_topic_0000001052623010_p66291220192816"></a>Module</p>
</th>
<th class="cellrowborder" valign="top" width="24.77%" id="mcps1.2.4.1.2"><p id="en-us_topic_0000001052623010_p3629122014289"><a name="en-us_topic_0000001052623010_p3629122014289"></a><a name="en-us_topic_0000001052623010_p3629122014289"></a>Platform</p>
</th>
<th class="cellrowborder" valign="top" width="54.010000000000005%" id="mcps1.2.4.1.3"><p id="en-us_topic_0000001052623010_p206298206288"><a name="en-us_topic_0000001052623010_p206298206288"></a><a name="en-us_topic_0000001052623010_p206298206288"></a>Description</p>
</th>
</tr>
</thead>
<tbody><tr id="en-us_topic_0000001052623010_row1162992082812"><td class="cellrowborder" valign="top" width="21.22%" headers="mcps1.2.4.1.1 "><p id="en-us_topic_0000001052623010_p136291920192814"><a name="en-us_topic_0000001052623010_p136291920192814"></a><a name="en-us_topic_0000001052623010_p136291920192814"></a>KV store</p>
</td>
<td class="cellrowborder" valign="top" width="24.77%" headers="mcps1.2.4.1.2 "><p id="en-us_topic_0000001052623010_p5629112019284"><a name="en-us_topic_0000001052623010_p5629112019284"></a><a name="en-us_topic_0000001052623010_p5629112019284"></a>LiteOS Cortex-M and LiteOS Cortex-A</p>
</td>
<td class="cellrowborder" valign="top" width="54.010000000000005%" headers="mcps1.2.4.1.3 "><p id="en-us_topic_0000001052623010_p3630112072811"><a name="en-us_topic_0000001052623010_p3630112072811"></a><a name="en-us_topic_0000001052623010_p3630112072811"></a>Provides KV storage for applications.</p>
</td>
</tr>
<tr id="en-us_topic_0000001052623010_row116301920152816"><td class="cellrowborder" valign="top" width="21.22%" headers="mcps1.2.4.1.1 "><p id="en-us_topic_0000001052623010_p96300207286"><a name="en-us_topic_0000001052623010_p96300207286"></a><a name="en-us_topic_0000001052623010_p96300207286"></a>File operation</p>
</td>
<td class="cellrowborder" valign="top" width="24.77%" headers="mcps1.2.4.1.2 "><p id="en-us_topic_0000001052623010_p1463032012281"><a name="en-us_topic_0000001052623010_p1463032012281"></a><a name="en-us_topic_0000001052623010_p1463032012281"></a>LiteOS Cortex-M</p>
</td>
<td class="cellrowborder" valign="top" width="54.010000000000005%" headers="mcps1.2.4.1.3 "><p id="en-us_topic_0000001052623010_p163042052810"><a name="en-us_topic_0000001052623010_p163042052810"></a><a name="en-us_topic_0000001052623010_p163042052810"></a>Provides unified file operation interfaces that can be used on different underlying chip components.</p>
</td>
</tr>
<tr id="en-us_topic_0000001052623010_row1163022022812"><td class="cellrowborder" valign="top" width="21.22%" headers="mcps1.2.4.1.1 "><p id="en-us_topic_0000001052623010_p66308202284"><a name="en-us_topic_0000001052623010_p66308202284"></a><a name="en-us_topic_0000001052623010_p66308202284"></a>Timer</p>
</td>
<td class="cellrowborder" valign="top" width="24.77%" headers="mcps1.2.4.1.2 "><p id="en-us_topic_0000001052623010_p26301620192820"><a name="en-us_topic_0000001052623010_p26301620192820"></a><a name="en-us_topic_0000001052623010_p26301620192820"></a>LiteOS Cortex-M and LiteOS Cortex-A</p>
</td>
<td class="cellrowborder" valign="top" width="54.010000000000005%" headers="mcps1.2.4.1.3 "><p id="en-us_topic_0000001052623010_p2630172062815"><a name="en-us_topic_0000001052623010_p2630172062815"></a><a name="en-us_topic_0000001052623010_p2630172062815"></a>Provides unified timer operation interfaces that can be used on different underlying chip components.</p>
</td>
</tr>
<tr id="en-us_topic_0000001052623010_row363012202282"><td class="cellrowborder" valign="top" width="21.22%" headers="mcps1.2.4.1.1 "><p id="en-us_topic_0000001052623010_p4502105418285"><a name="en-us_topic_0000001052623010_p4502105418285"></a><a name="en-us_topic_0000001052623010_p4502105418285"></a>JavaScript API</p>
</td>
<td class="cellrowborder" valign="top" width="24.77%" headers="mcps1.2.4.1.2 "><p id="en-us_topic_0000001052623010_p199870135293"><a name="en-us_topic_0000001052623010_p199870135293"></a><a name="en-us_topic_0000001052623010_p199870135293"></a>LiteOS Cortex-A</p>
</td>
<td class="cellrowborder" valign="top" width="54.010000000000005%" headers="mcps1.2.4.1.3 "><p id="en-us_topic_0000001052623010_p1550005422814"><a name="en-us_topic_0000001052623010_p1550005422814"></a><a name="en-us_topic_0000001052623010_p1550005422814"></a>Provides JavaScript APIs for obtaining device information and storing data.</p>
</td>
</tr>
<tr id="en-us_topic_0000001052623010_row5553145162815"><td class="cellrowborder" valign="top" width="21.22%" headers="mcps1.2.4.1.1 "><p id="en-us_topic_0000001052623010_p106300200288"><a name="en-us_topic_0000001052623010_p106300200288"></a><a name="en-us_topic_0000001052623010_p106300200288"></a>System attribute dumping</p>
</td>
<td class="cellrowborder" valign="top" width="24.77%" headers="mcps1.2.4.1.2 "><p id="en-us_topic_0000001052623010_p16300204280"><a name="en-us_topic_0000001052623010_p16300204280"></a><a name="en-us_topic_0000001052623010_p16300204280"></a>LiteOS Cortex-M and LiteOS Cortex-A</p>
</td>
<td class="cellrowborder" valign="top" width="54.010000000000005%" headers="mcps1.2.4.1.3 "><p id="en-us_topic_0000001052623010_p1563018208286"><a name="en-us_topic_0000001052623010_p1563018208286"></a><a name="en-us_topic_0000001052623010_p1563018208286"></a>Provides the command line tool for dumping system attributes.</p>
</td>
</tr>
</tbody>
</table>
## Directory Structure<a name="section1464106163817"></a>
```
utils/native/lite/ # Root directory
├── file # Implementation of the file system APIs
├── hals # HAL directory
│ └── file # Header files of the hardware abstraction layer for file operations
├── include # Header files of external APIs
├── js # JavaScript APIs
│ └── builtin
│ ├── common
│ ├── deviceinfokit # Device information kit
│ ├── filekit # File kit
│ └── kvstorekit # KV store kit
├── kal # KAL directory
│ └── timer # KAL implementation of the timer
├── kv_store # KV store implementation
│ ├── innerkits # Internal KV store APIs
│ └── src # KV store source file
├── memory
│ └── include # Memory pool management APIs
├── os_dump # System attribute dumping
└── timer_task # Timer implementation
```
## Usage<a name="section25021123178"></a>
- **KV store**
```
// Store or update the value of a key.
const char key1[] = "key_sample";
const char defValue[] = "test case of key value store.";
int ret = UtilsSetValue(key1, defValue);
// Obtain the value of the key.
char value1[32] = {0};
ret = UtilsGetValue(key1, value1, 32);
// Delete the value of the key.
UtilsDeleteValue(key1);
```
- **File operation**
```
// Open or create a file.
const char fileName[] = "testfile";
int fd = UtilsFileOpen(fileName, O_RDWR_FS | O_CREAT_FS | O_TRUNC_FS, 0);
// Write a specified length of data into a file with the specified file descriptor.
const char defValue[] = "test case of file system.";
int ret = UtilsFileWrite(fd, defValue, strlen(defValue));
// Close a file with a specified file descriptor.
UtilsFileClose(fd);
// Obtain the file size.
int fileLen = 0;
ret = UtilsFileStat(fileName, &fileLen);
printf("file size = %d\n", fileLen);
// Adjust the read and write position offset in a file.
int fd1 = UtilsFileOpen(fileName, O_RDWR_FS, 0);
ret = UtilsFileSeek(fd1, 5, SEEK_SET_FS);
// Read a specified length of data from a file with the specified file descriptor and write the data into the buffer.
char buf[32] = {0};
int readLen = UtilsFileRead(fd1, buf, 32);
ret = UtilsFileClose(fd1);
printf("read len = %d : buf = %s\n", readLen, buf);
// Delete a specified file.
ret = UtilsFileDelete(fileName);
```
- **System attribute dumping**
LiteOS Cortex-M kernel: Run the following command over the serial port to dump the current system parameters:
```
AT+SYSPARA
```
LiteOS Cortex-A kernel: Run the **os\_dump** command in the **bin** directory to dump the current system parameters:
```
./bin/os_dump syspara
```
## Repositories Involved<a name="section4571352889"></a>
[Utils](https://gitee.com/openharmony/docs/blob/master/en/readme/utils.md)
utils\_native\_lite