# commonlibrary/utils_lite
- [Overview](#section62661387114)
- [Directory Structure](#section1464106163817)
- [Usage](#section25021123178)
- [Repositories Involved](#section4571352889)
## Overview
The utils_lite repository stores basic components of OpenHarmony. These basic components are used by OpenHarmony subsystems and upper-layer applications.
The utils_lite library provides the following capabilities on different platforms:
- LiteOS Cortex-M \(Hi3861 platform\): file operations and timer
- LiteOS Cortex-A \(Hi3516 or Hi3518 platform\): timer and JavaScript APIs for device query and data storage
**Table 1** Utils_lite capabilities
Module
Platform
Description
File operation
LiteOS Cortex-M
Provides unified file operation interfaces that can be used on different underlying chip components.
Timer
LiteOS Cortex-M and LiteOS Cortex-A
Provides unified timer operation interfaces that can be used on different underlying chip components.
JavaScript API
LiteOS Cortex-A
Provides JavaScript APIs for obtaining device information and storing data.
## Directory Structure
```
commonlibrary/utils_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 # Builtin common function
│ ├── deviceinfokit # Device information kit
│ ├── filekit # File kit
│ └── kvstorekit # KV store kit
├── kal # KAL directory
│ └── timer # KAL implementation of the timer
├── memory
│ └── include # Memory pool management APIs
└── timer_task # Timer implementation
```
## Usage
- **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);
```
## Repositories Involved
[commonlibrary](https://gitee.com/openharmony/docs/blob/master/en/readme/utils.md)
[**commonlibrary\_utils\_lite**](https://gitee.com/openharmony/commonlibrary_utils_lite)