Qt for HarmonyOS/qtohosextras doc/File Permissions Example

File Permissions Example

Demonstrates how to use the file permissions API in QtOhosExtras to grant and check access to files.

Screenshot of the file permissions example application.

To test the API, click the Select File button to choose a file. Each button in the left column corresponds to a different file permission API function:

• Persist
• Revoke
• Activate
• Deactivate
• Check

You can also select the desired access mode (read, write, or read | write) using the radio buttons on the right. The selected mode and file path are stored in a PathPolicy structure, which is passed as input to the API.

At the bottom of the screen, the result of each operation is logged. These logs are based on the return values of the API functions.

Input Data Definition

All API functions operate on a list of PathPolicy structures. Each PathPolicy contains a file path and an operation mode. Here is an example of how to create a PathPolicy:

     auto pathPolicy = QSharedPointer<QtOhosExtras::FileShare::PathPolicy>::create(
         QtOhosExtras::FileShare::PathPolicy{
             .path = QLatin1String(),
             .operationModes = initialOperationMode,
         });

In this snippet, the path field is initialized as an empty string. A valid path must be provided for the PathPolicy to be usable. In this example, the path is set later when the user selects a file with the Select File button.

Using the API Functions

In this example, API calls are triggered by button clicks.

Action function calls:

     QObject::connect(
         actionsGroup, QOverload<int>::of(&QButtonGroup::buttonClicked),
         logContext,
         [logContext, pathPolicy](int id) {
             QList<QtOhosExtras::FileShare::PathPolicy> input = {{*pathPolicy}};

             const auto result = actionOptions[id].actionFunction(input);
             logActionResult(logContext, actionOptions[id].label, result, pathPolicy);
         });

The lambda shown above creates a list containing the current PathPolicy and then calls the appropriate API function through the actionOptions table. The following line performs the actual API call:

 const auto result = actionOptions[id].actionFunction(input);

Check function call:

     QObject::connect(
         checkButton, &QPushButton::clicked, logContext,
         [logContext, pathPolicy]() {
             QList<QtOhosExtras::FileShare::PathPolicy> input = {{*pathPolicy}};

             const auto result = QtOhosExtras::FileShare::checkPersistent(input);
             logCheckResult(logContext, result);
         });

In this case, the lambda creates a list containing the current PathPolicy and then calls the checkPersistent function directly:

 const auto result = QtOhosExtras::FileShare::checkPersistent(input);

All API functions (except checkPersistent) return a result class that provides:

• Operation status per input path
• A list of individual error results

The following code logs the result of an action function. It first logs the operation status, followed by any errors:

 void logActionResult(
     QTextEdit *logContext, const QString &actionName,
     QSharedPointer<QtOhosExtras::FileShare::ActionResult> actionResult,
     QSharedPointer<QtOhosExtras::FileShare::PathPolicy> pathPolicy)
 {
     logMessage(
         logContext,
         QStringLiteral("%1 on file: %2")
             .arg(buildOperationStatusText(actionName, actionResult->operationStatus()))
             .arg(pathPolicy->path));

     const auto &errorInfoList = actionResult->errorInfoList();
     if (!errorInfoList.empty()) {
         logMessage(logContext, QLatin1String("Error info list:"));
     }
     for (const auto &errorInfo : errorInfoList) {
         logMessage(logContext, QStringLiteral("Path: %1").arg(errorInfo.path));
         logMessage(
             logContext, QStringLiteral("Error code: %1").arg(static_cast<int>(errorInfo.error)));
         logMessage(logContext, QStringLiteral("Error message: %1").arg(errorInfo.errorMessage));
     }
 }

The actionResult parameter is a QtOhosExtras::FileShare::ActionResult, which contains the operation status for each input path and a list of error details (if any). The pathPolicy parameter is a QtOhosExtras::FileShare::PathPolicy, which provides the file path and operation mode used in the API call.

To check whether a permission is granted, use the checkPersistent function, which returns a check result class. The check result class provides:

• Operation status per input path
• Check results for each input path

The following code logs the result of the checkPersistent function. It first logs the operation status, followed by the check results:

 void logCheckResult(
     QTextEdit *logContext, QSharedPointer<QtOhosExtras::FileShare::CheckResult> checkResult)
 {
     logMessage(
         logContext,
         buildOperationStatusText(QLatin1String("Check"), checkResult->operationStatus()));

     for (const auto &result : checkResult->checkResultList()) {
         logMessage(
             logContext,
             QStringLiteral("Persistent permission %1 %2 on file: %3")
                 .arg(buildPolicyModeText(result.policy.operationModes))
                 .arg((result.result ? QLatin1String("is granted") : QLatin1String("is not granted")))
                 .arg(result.policy.path));
     }
 }

Files:

• filepermissions/filepermissions.pro
• filepermissions/main.cpp

See also QtOhosExtras::FileShare.