1# 授权持久化(C/C++)
2
3## 场景介绍
4
5应用通过Picker获取临时授权，临时授权在应用退出后或者设备重启后会清除，如果应用重启或者设备重启后需要直接访问之前已访问过的文件，则对文件进行[持久化授权](file-persistPermission.md#场景介绍)。FileShare提供了支持基于URI的文件及目录授于持久化权限、权限激活、权限查询等方法。
6
7## 接口说明
8
9接口的详细介绍请参见[API参考](../reference/apis-core-file-kit/file_share.md)。
10
11| 接口名称 | 描述 |
12| -------- | -------- |
13| OH_FileShare_PersistPermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | 对所选择的多个文件或目录URI持久化授权。 |
14| OH_FileShare_RevokePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | 对所选择的多个文件或目录URI取消持久化授权。 |
15| OH_FileShare_ActivatePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | 使能多个已经永久授权过的文件或目录URI。 |
16| OH_FileShare_DeactivatePermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, FileShare_PolicyErrorResult **result, unsigned int *resultNum) | 取消使能授权过的多个文件或目录URI。 |
17| OH_FileShare_CheckPersistentPermission(const FileShare_PolicyInfo *policies, unsigned int policyNum, bool **result, unsigned int *resultNum) | 校验所选择的多个文件或目录URI的持久化权限结果。 |
18| OH_FileShare_ReleasePolicyErrorResult(FileShare_PolicyErrorResult *errorResult, unsigned int resultNum) | 释放FileShare_PolicyErrorResult内存。 |
19
20## 约束与限制
21
22- 使用文件分享的相关接口，需确认设备具有以下系统能力：SystemCapability.FileManagement.AppFileService.FolderAuthorization。
23
24- 在调用文件分享的相关接口前，需要申请权限："ohos.permission.FILE_ACCESS_PERSIST"，申请方式请参考[访问控制-申请应用权限](../security/AccessToken/determine-application-mode.md)。
25
26## 开发步骤
27
28以下步骤描述了如何使用`FileShare`提供的Native API接口。
29
30**添加动态链接库**
31
32CMakeLists.txt中添加以下lib。
33
34```txt
35target_link_libraries(sample PUBLIC libohfileshare.so)
36```
37
38**头文件**
39
40```c++
41#include <filemanagement/fileshare/oh_file_share.h>
42#include <iostream>
43```
441. 创建FileShare_PolicyInfo实例,调用OH_FileShare_PersistPermission接口，设置URI的持久化授权，接口入参policyNum最大上限为500。
45    ```c++
46    static const uint32_t POLICY_NUM = 2;
47    char strTestPath1[] = "file://com.example.fileshare/data/storage/el2/base/files/test1.txt";
48    char strTestPath2[] = "file://com.example.fileshare/data/storage/el2/base/files/test2.txt";
49    FileShare_PolicyInfo policy[POLICY_NUM] = {
50        {strTestPath1, static_cast<unsigned int>(strlen(strTestPath1)), FileShare_OperationMode::READ_MODE},
51        {strTestPath2, static_cast<unsigned int>(strlen(strTestPath2)), FileShare_OperationMode::WRITE_MODE}};
52    FileShare_PolicyErrorResult* result = nullptr;
53    uint32_t resultNum = 0;
54    auto ret = OH_FileShare_PersistPermission(policy, POLICY_NUM, &result, &resultNum);
55    if (ret != ERR_OK) {
56        if (ret == ERR_EPERM && result != nullptr) {
57            for(uint32_t i = 0; i < resultNum; i++) {
58                std::cout << "error uri: " <<  result[i].uri << std::endl;
59                std::cout << "error code: " <<  result[i].code << std::endl;
60                std::cout << "error message: " << result[i].message << std::endl;
61            }
62        }
63    }
64    OH_FileShare_ReleasePolicyErrorResult(result, resultNum);
65    ```
662. 调用OH_FileShare_ActivatePermission接口，激活启用已授权过的URI，接口入参policyNum最大上限为500。
67    ```c++
68    auto ret = OH_FileShare_ActivatePermission(policy, POLICY_NUM, &result, &resultNum);
69    if (ret != ERR_OK) {
70        if (ret == ERR_EPERM && result != nullptr) {
71            for(uint32_t i = 0; i < resultNum; i++) {
72                std::cout << "error uri: " <<  result[i].uri << std::endl;
73                std::cout << "error code: " <<  result[i].code << std::endl;
74                std::cout << "error message: " << result[i].message << std::endl;
75            }
76        }
77    }
78    OH_FileShare_ReleasePolicyErrorResult(result, resultNum);
79    ```
803. 调用OH_FileShare_DeactivatePermission接口，停止已启用授权过URI的访问权限，接口入参policyNum最大上限为500。
81    ```c++
82    auto ret = OH_FileShare_DeactivatePermission(policy, POLICY_NUM, &result, &resultNum);
83    if (ret != ERR_OK) {
84        if (ret == ERR_EPERM && result != nullptr) {
85            for(uint32_t i = 0; i < resultNum; i++) {
86                std::cout << "error uri: " <<  result[i].uri << std::endl;
87                std::cout << "error code: " <<  result[i].code << std::endl;
88                std::cout << "error message: " << result[i].message << std::endl;
89            }
90        }
91    }
92    OH_FileShare_ReleasePolicyErrorResult(result, resultNum);
93    ```
944. 调用OH_FileShare_RevokePermission接口，撤销已经授权的URI持久化权限，接口入参policyNum最大上限为500。
95    ```c++
96    auto ret = OH_FileShare_RevokePermission(policy, POLICY_NUM, &result, &resultNum);
97    if (ret != ERR_OK) {
98        if (ret == ERR_EPERM && result != nullptr) {
99            for(uint32_t i = 0; i < resultNum; i++) {
100                std::cout << "error uri: " <<  result[i].uri << std::endl;
101                std::cout << "error code: " <<  result[i].code << std::endl;
102                std::cout << "error message: " << result[i].message << std::endl;
103            }
104        }
105    }
106    OH_FileShare_ReleasePolicyErrorResult(result, resultNum);
107    ```
1085. 调用OH_FileShare_CheckPersistentPermission接口，检查URI持久化权限，接口入参policyNum最大上限为500。
109    ```c++
110    bool *result = nullptr;
111    auto ret = OH_FileShare_CheckPersistentPermission(policy, POLICY_NUM, &result, &resultNum);
112    if (result != nullptr && resultNum > 0) {
113        for(uint32_t i = 0; i < resultNum && resultNum <= POLICY_NUM; i++) {
114            std::cout << "uri: " <<  policy[i].uri << std::endl;
115            std::cout << "result: " <<  result[i] << std::endl;
116        }
117    }
118    std::cout << "retCode: " <<  ret << std::endl;
119    free(result);
120    ```