ya0guang commented on a change in pull request #5:
URL:
https://github.com/apache/incubator-teaclave-website/pull/5#discussion_r695803212
##########
File path:
site/blog/2021-08-13-developing-sgx-application-with-teaclave-sgx-sdk.md
##########
@@ -269,32 +269,90 @@ pub fn intersection(nums1: Vec<i32>, nums2: Vec<i32>) ->
Vec<i32> {
}
```
-需要调用该函数时，在 `say_something` 中添加：
+考虑一个比较现实的场景，两个用户分别将自己的向量作为参数传入 enclave 中进行计算，这时候数据需要从不可信代码区域复制到可信代码区域。
+首先，需要在 `Enclave.edl` 文件中修改 `say_something` 函数的定义，输入参数为两个用户的向量指针以及对应的大小。
+```edl
+public sgx_status_t say_something([in, size=len1] size_t* num1, size_t len1,
+ [in, size=len2] size_t* num2, size_t len2);
+```
+
+接着，在 `app.c` 文件中声明需要求交集的数组以及大小并仿照示例调用 `say_something`。
+
+```c
+ size_t nums1[10] = {0,1,2,3,4,5,6,7,8,9};
+ size_t nums2[10] = {5,6,7,8,9,10,11,12,13,14};
+ size_t len1 = sizeof(nums1);
+ size_t len2 = sizeof(nums2);
+
+ sgx_ret = say_something(global_eid,
+ &enclave_ret,
+ nums1,
+ len1,
+ nums2,
+ len2);
+```
+
+回到 `enclave/src/lib.rs`，`say_something` 传进来的是两个向量的起始地址以及大小。
```rust
- println!("\nTry intersection for our own");
- let nums1: Vec<i32> = vec![1, 2, 3, 4, 5];
- let nums2: Vec<i32> = vec![4, 5, 6, 7, 8];
- let vec: Vec<i32> = intersection(nums1, nums2);
- println!("intersection set is {:?}", vec);
+pub extern "C" fn say_something(nums1: *mut usize, len1: usize, nums2: *mut
usize, len2: usize) -> sgx_status_t
+```
+由于数据是从非安全区复制到安全区的，还需要对 `intersection`
函数进行部分改写。传进来的参数是向量指针，以指针地址为起始地址，根据大小参数限制迭代范围并获得一个用于循环的序号变量 `i`，在 `for` 循环中使用
`offset` 偏移指针，解引用它，读出 `nums1` 和 `nums2` 的元素值。
+```rust
+pub fn intersection(nums1: *mut usize, len1: usize, nums2: *mut usize, len2:
usize) -> Vec<usize> {
+ use std::collections::HashSet;
+ let mut set: HashSet<usize> = HashSet::new();
+ let mut vec: Vec<usize> = Vec::new();
+
+ for i in 0..len1/mem::size_of::<usize>() {
+ let mut val_nums1 = 0;
+ unsafe {
+ val_nums1 = *nums1.offset(i as isize);
+ }
+ set.insert(val_nums1);
+ }
+
Review comment:
这里应该也可以使用`std::slice::from_raw_parts`来构建一个`&[<type>]`。
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