修复未对齐问题, 添加一个 readi16 be api(虽说用不上

shen-nbt5/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "shen-nbt5"
-version = "0.4.3"
+version = "0.4.4"
 edition = "2021"
 description = "Just A FASSST NBT parser/writer"
 homepage = "https://github.com/shenjackyuanjie/nbt-rust"

shen-nbt5/src/reader.rs

@@ -721,6 +721,26 @@ impl NbtReader<'_> {
         self.cursor += len;
         value
     }
+    /// 读取指定长度的 i16 数组
+    ///
+    /// # 安全性
+    ///
+    /// 长度溢出会导致 UB
+    #[inline]
+    pub unsafe fn read_be_i16_array_unsafe(&mut self, len: usize) -> Vec<i16> {
+        let mut value: Vec<i16> = Vec::with_capacity(len);
+        std::ptr::copy_nonoverlapping(
+            self.data[self.cursor..].as_ptr() as *const u8,
+            value.as_ptr() as *mut u8,
+            len * 2,
+        );
+        value.set_len(len);
+        for n in &mut value {
+            *n = n.to_be();
+        }
+        self.cursor += len * 2;
+        value
+    }
     /// 读取指定长度的 i32 数组
     ///
     /// # 安全性
@@ -728,15 +748,39 @@ impl NbtReader<'_> {
     /// 长度溢出会导致 UB
     #[inline]
     pub unsafe fn read_be_i32_array_unsafe(&mut self, len: usize) -> Vec<i32> {
-        let value =
-            std::slice::from_raw_parts(self.data[self.cursor..].as_ptr() as *const i32, len);
-        let mut value = value.to_vec();
+        let mut value: Vec<i32> = Vec::with_capacity(len);
+        std::ptr::copy_nonoverlapping(
+            self.data[self.cursor..].as_ptr() as *const u8,
+            value.as_ptr() as *mut u8,
+            len * 4,
+        );
+        value.set_len(len);
         for n in &mut value {
             *n = n.to_be();
         }
         self.cursor += len * 4;
         value
     }
+    /// 读取指定长度的 i64 数组
+    ///
+    /// # 安全性
+    ///
+    /// 长度溢出会导致 UB
+    #[inline]
+    pub unsafe fn read_be_i64_array_unsafe(&mut self, len: usize) -> Vec<i64> {
+        let mut value: Vec<i64> = Vec::with_capacity(len);
+        std::ptr::copy_nonoverlapping(
+            self.data[self.cursor..].as_ptr() as *const u8,
+            value.as_ptr() as *mut u8,
+            len * 8,
+        );
+        value.set_len(len);
+        for n in &mut value {
+            *n = n.to_be();
+        }
+        self.cursor += len * 8;
+        value
+    }
     /// 读取指定长度的 i32 数组
     ///
     /// # 安全性
@@ -755,22 +799,6 @@ impl NbtReader<'_> {
     ///
     /// # 安全性
     ///
-    /// 长度溢出会导致 UB
-    #[inline]
-    pub unsafe fn read_be_i64_array_unsafe(&mut self, len: usize) -> Vec<i64> {
-        let value =
-            std::slice::from_raw_parts(self.data[self.cursor..].as_ptr() as *const i64, len);
-        let mut value = value.to_vec();
-        for n in &mut value {
-            *n = n.to_be();
-        }
-        self.cursor += len * 8;
-        value
-    }
-    /// 读取指定长度的 i64 数组
-    ///
-    /// # 安全性
-    ///
     /// 长度溢出会导致 panic
     #[inline]
     pub fn read_be_i64_array(&mut self, len: usize) -> Vec<i64> {

shen-nbt5/src/tests.rs

@@ -280,6 +280,46 @@ mod unsafe_test {
             assert_eq!(reader.cursor, 100 * 8);
         }
     }
+
+    /// 未对齐的地址
+    #[test]
+    fn unaligned_read_u16_array() {
+        let mut value = vec![0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04];
+        let mut reader = NbtReader::new(&mut value);
+        let value = reader.read_u8();
+        assert_eq!(value, 0x01);
+        assert_eq!(reader.cursor, 1);
+        unsafe {
+            // 读取 u16 数组
+            let array = reader.read_be_i16_array_unsafe(3);
+            assert_eq!(array, vec![0x0203, 0x0401, 0x0203]);
+            assert_eq!(reader.cursor, 7);
+            let value = reader.read_u8();
+            assert_eq!(value, 0x04);
+            assert_eq!(reader.cursor, 8);
+        }
+    }
+
+    /// 依然是未对齐
+    /// 只不过是 u32/i32
+    #[test]
+    fn unaligned_read_x32_array() {
+        let mut value = gen_datas(202);
+        let mut reader = NbtReader::new(&mut value);
+        let value = reader.read_u8();
+        assert_eq!(value, 0x00);
+        assert_eq!(reader.cursor, 1);
+        unsafe {
+            let array = reader.read_be_i32_array_unsafe(50);
+            reader.roll_back(50 * 4);
+            let safe_array = reader.read_be_i32_array(50);
+            assert_eq!(array, safe_array);
+            assert_eq!(reader.cursor, 201);
+        }
+        let value = reader.read_u8();
+        assert_eq!(value, 201);
+        assert_eq!(reader.cursor, 202);
+    }
 }
 
 mod nbt {