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.
For details about the APIs, see oh_file_uri.h.
| 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) | Enables multiple persistently authorized file or directory URIs. |
| 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. |
Before using the FileShare APIs, check that your device has SystemCapability.FileManagement.AppFileService.FolderAuthorization.
Before calling file sharing APIs, you must request the permission: ohos.permission.FILE_ACCESS_PERSIST. For details about how to request permissions, see Workflow for Requesting Permissions.
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>
Create a FileShare_PolicyInfo instance, call the OH_FileShare_PersistPermission API, and set the persistence permission for the URI. The maximum limit of the input parameter 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);