Utils Development

Available APIs

Table 1 APIs for file operations

Function Description
int UtilsFileOpen(const char* path, int oflag, int mode) Opens or creates a file.
int UtilsFileClose(int fd) Closes a file with a specified file descriptor.
int UtilsFileRead(int fd, char *buf, unsigned int len) Reads a specified length of data from a file with the specified file descriptor and writes the data into the buffer.
int UtilsFileWrite(int fd, const char *buf, unsigned int len) Writes a specified length of data into a file with the specified file descriptor.
int UtilsFileDelete(const char *path) Deletes a specified file.
int UtilsFileStat(const char *path, unsigned int *fileSize) Obtains the file size.
int UtilsFileSeek(int fd, int offset, unsigned int whence) Adjusts the read and write position offset in a file.
int UtilsFileCopy(const char* src, const char* dest) Copies the source file to a target file.
int UtilsFileMove(const char* src, const char* dest) Moves the source file into a target file.

Sample code for file operations:

// Open a file and write data.
char fileName[] = "testfile";
static const char def[] = "utils_file_operation implement.";
int fd = UtilsFileOpen(fileName, O_RDWR_FS | O_CREAT_FS | O_TRUNC_FS, 0);
printf("file handle = %d\n", fd);
int ret = UtilsFileWrite(fd, def, strlen(def));
printf("write ret = %d\n", ret);

// Adjust the position offset in the file.
ret = UtilsFileSeek(fd, 5, SEEK_SET_FS);
printf("lseek ret = %d\n", ret);

// Read data and close the file.
char buf[64] = {0};
int readLen = UtilsFileRead(fd, buf, 64);
ret = UtilsFileClose(fd);
printf("read len = %d : buf = %s\n", readLen, buf);

// Obtain the file size.
int fileLen = 0;
ret = UtilsFileStat(fileName, &fileLen);
printf("file size = %d\n", fileLen);

// Delete the file.
ret = UtilsFileDelete(fileName);
printf("delete ret = %d\n", ret);

Table 2 APIs for KV store operations

Function Description
int UtilsGetValue(const char* key, char* value, unsigned int len) Obtains the value matching a specified key from the file system or cache.
int UtilsSetValue(const char* key, const char* value) Adds or updates the value matching a specified key in the file system or cache.
int UtilsDeleteValue(const char* key) Deletes the value matching a specified key from the file system or cache.

Sample code for the KV store:

// Set the value matching the specified key.
char key[] = "rw.sys.version_100";
char value[] = "Hello kv operation implement!";
int ret = UtilsSetValue(key, value);
printf("UtilsSetValue set ret = %d\n", ret);

// Obtain the value matching the specified key.
char temp[128] = {0};
ret = UtilsGetValue(key, temp, 128);
printf("UtilsGetValue get ret = %d, temp = %s\n", ret, temp);

// Delete the value matching the specified key.
ret = UtilsDeleteValue(key);
printf("UtilsDeleteValue delete ret = %d\n", ret);

How to Develop

Developing a Native Application for the KV Store That Uses the LiteOS Cortex-A Kernel (Hi3516 or Hi3518)

  1. Develop the native application for the KV store using AbilityKit APIs.

    • Write the user program by calling the APIs provided by the KV store and compile the libLauncher.so file.

      // Set the value matching the specified key.
char key[] = "rw.sys.version_100";
char value[] = "Hello kv operation implement!";
int ret = UtilsSetValue(key, value);
printf("UtilsSetValue set ret = %d\n", ret);

// Obtain the value matching the specified key.
char temp[128] = {0};
ret = UtilsGetValue(key, temp, 128);
printf("UtilsGetValue get ret = %d, temp = %s\n", ret, temp);

// Delete the value matching the specified key.
ret = UtilsDeleteValue(key);
printf("UtilsDeleteValue delete ret = %d\n", ret);

    • Edit the config.json file as follows:

      {
    "app": {
        "bundleName": "com.example.launcher",
        "vendor": "example,
        "version": {
            "code": 1,
            "name": "1.0"
        }
    },
    "deviceConfig": {
        "default": {
            "reqSdk": {
                "compatible": "zsdk 1.0.0",
                "target": "zsdk 1.0.1"
            },
            "keepAlive": false
        },
        "smartCamera": {
            "reqSdk": {
                "compatible": "zsdk 1.0.0",
                "target": "zsdk 1.0.1"
            },
            "keepAlive": false
        }
    },
    "module": {
        "package": "com.example.launcher",
        "name": ".MyHarmonyAbilityPackage",
        "deviceType": [
            "phone", "tv","tablet", "pc","car","smartWatch","sportsWatch","smartCamera"
        ], 
        "distro": {
            "deliveryWithInstall": true, 
            "moduleName": "Launcher", 
            "moduleType": "entry"
        },
        "abilities": [{
            "name": "MainAbility",
            "icon": "res/drawable/phone.png",
            "label": "test app 1", 
            "launchType": "standard",
            "type": "page"
        },
        {
            "name": "SecondAbility",
            "icon": "res/drawable/phone.png",
            "label": "test app 2", 
            "launchType": "standard",
            "type": "page"
        },
        {
            "name": "ServiceAbility",
            "icon": "res/drawable/phone.png",
            "label": "test app 2", 
            "launchType": "standard",
            "type": "service"
        }
        ]
    }
}

    • Generate a HAP file.

      • Add resource files in the res/drawable directory based on the following directory structure.

      • Compress the libLauncher.so, config.json, and resource files into a ZIP package and change the file name extension to .hap, for example, Launcher.hap.

  2. Connect the development board and send the command for installing the native KV store application to the board through the serial port.

    ./nfs/dev_tools/bin/bm install -p /nfs/Launcher.hap

  3. Send the command for running the native KV store application to the board through the serial port.

    ./nfs/dev_tools/bin/aa start -p com.example.launcher -n ServiceAbility

Dumping System Attributes on the Platform That Uses the LiteOS Cortex-M Kernel

  1. Connect the development board and send the AT+SYSPARA command to the board through the serial port.

    AT+SYSPARA

    Figure 1 Output of the system attribute dumping command for the LiteOS Cortex-M kernel

Dumping System Attributes on the Platform That Uses the LiteOS Cortex-A Kernel

  1. Connect the development board and run the os_dump --help command in the bin directory to view the os_dump help information.

    ./bin/os_dump --help

  2. Run the os_dump -l command in the bin directory to view system modules that support attribute dumping.

    ./bin/os_dump -l

  3. Run the os_dump syspara command in the bin directory to dump the current system attributes.

    ./bin/os_dump syspara

    Figure 2 Output of the system attribute dumping command for the LiteOS Cortex-A kernel