Persisting Temporary Permissions (C/C++)
When to Use
If an application accesses a file by using Picker, the permission for accessing the file will be automatically invalidated after the application exits or the device restarts. To retain the permission for accessing the file, you need to persist the permission. You can use the FileShare module to manage persistent permissions on files or directories based on their URIs, including activating, deactivating, and checking these permissions.
Available APIs
For details about the APIs, see API Reference.
| API | Description |
|---|---|
| OH_FileShare_PersistPermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | Persists the permissions on files or directories. |
| OH_FileShare_RevokePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | Revokes the permissions from files or directories. |
| OH_FileShare_ActivatePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | Activates the persistent permissions on files or directories. |
| OH_FileShare_DeactivatePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | Deactivates the persistent permissions on files or directories. |
| OH_FileShare_CheckPersistentPermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, bool **result, unsigned int *resultNum) | Checks the persistent permissions on files or directories. |
| OH_FileShare_ReleasePolicyErrorResult(FileShare_PolicyErrorResult *errorResult, unsigned int resultNum) | Releases the memory allocated for FileShare_PolicyErrorResult. |
Constraints
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Before using the FileShare APIs, check that your device has SystemCapability.FileManagement.AppFileService.FolderAuthorization.
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To call FileShare APIs, the application must have the ohos.permission.FILE_ACCESS_PERSIST permission. For details about how to request the permission, see Workflow for Using Permissions.
How to Develop
The following example describes how to use the FileShare APIs.
Adding the Dynamic Link Library
Add the following library to CMakeLists.txt.
target_link_libraries(sample PUBLIC libohfileshare.so)
Including Header Files
#include <filemanagement/fileshare/oh_file_share.h>
#include <iostream>
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Create a FileShare_PolicyInfo instance, and use OH_FileShare_PersistPermission to persist the permissions on files based on their URI. The maximum value of policyNum is 500.
static const uint32_t policyNum = 2; char strTestPath1[] = "file://com.example.fileshare/data/storage/el2/base/files/test1.txt"; char strTestPath2[] = "file://com.example.fileshare/data/storage/el2/base/files/test2.txt"; FileShare_PolicyInfo policy[policyNum] = { {strTestPath1, static_cast<unsigned int>(strlen(strTestPath1)), FileShare_OperationMode::READ_MODE}, {strTestPath2, static_cast<unsigned int>(strlen(strTestPath2)), FileShare_OperationMode::WRITE_MODE}}; FileShare_PolicyErrorResult* result = nullptr; uint32_t resultNum = 0; napi_value napiResult; std::string resultStr; auto ret = OH_FileShare_PersistPermission(policy, policyNum, &result, &resultNum); if (ret != ERR_OK) { if (ret == ERR_EPERM && result != nullptr) { for (uint32_t i = 0; i < resultNum; i++) { std::cout << "error uri: " << result[i].uri << std::endl; std::cout << "error code: " << result[i].code << std::endl; std::cout << "error message: " << result[i].message << std::endl; // ... } } } OH_FileShare_ReleasePolicyErrorResult(result, resultNum); -
Call OH_FileShare_ActivatePermission to activate the persistent permissions on files. The maximum value of policyNum is 500.
auto ret = OH_FileShare_ActivatePermission(policy, policyNum, &result, &resultNum); if (ret != ERR_OK) { if (ret == ERR_EPERM && result != nullptr) { for (uint32_t i = 0; i < resultNum; i++) { std::cout << "error uri: " << result[i].uri << std::endl; std::cout << "error code: " << result[i].code << std::endl; std::cout << "error message: " << result[i].message << std::endl; // ... } } } OH_FileShare_ReleasePolicyErrorResult(result, resultNum); -
Call OH_FileShare_DeactivatePermission to deactivate the persistent permissions on files. The maximum value of policyNum is 500.
auto ret = OH_FileShare_DeactivatePermission(policy, policyNum, &result, &resultNum); if (ret != ERR_OK) { if (ret == ERR_EPERM && result != nullptr) { for (uint32_t i = 0; i < resultNum; i++) { std::cout << "error uri: " << result[i].uri << std::endl; std::cout << "error code: " << result[i].code << std::endl; std::cout << "error message: " << result[i].message << std::endl; // ... } } } OH_FileShare_ReleasePolicyErrorResult(result, resultNum); -
Call OH_FileShare_RevokePermission to revoke the persistent permissions from files. The maximum value of policyNum is 500.
auto ret = OH_FileShare_RevokePermission(policy, policyNum, &result, &resultNum); if (ret != ERR_OK) { if (ret == ERR_EPERM && result != nullptr) { for (uint32_t i = 0; i < resultNum; i++) { std::cout << "error uri: " << result[i].uri << std::endl; std::cout << "error code: " << result[i].code << std::endl; std::cout << "error message: " << result[i].message << std::endl; // ... } } } OH_FileShare_ReleasePolicyErrorResult(result, resultNum); -
Call OH_FileShare_CheckPersistentPermission to check the persistent permissions on files. The maximum value of policyNum is 500.
bool *result = nullptr; auto ret = OH_FileShare_CheckPersistentPermission(policy, policyNum, &result, &resultNum); if (ret != ERR_OK) { if (ret == ERR_EPERM && result != nullptr) { for (uint32_t i = 0; i < resultNum && resultNum <= policyNum; i++) { std::cout << "uri: " << policy[i].uri << std::endl; std::cout << "result: " << result[i] << std::endl; // ... } } } std::cout << "retCode: " << ret << std::endl; free(result);