Utils

• Overview
• Directory Structure
• Usage
• Repositories Involved

Overview

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

Directory Structure

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              # Builtin common function
│       ├── 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
└── timer_task                  # Timer implementation

Usage

• 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);

Repositories Involved

Utils

utils_native_lite