Create win_virtual_mem.rs

VirtualAlloc Rust/win_virtual_mem.rs

@@ -0,0 +1,46 @@
+use std::ptr::NonNull;
+use windows::Win32::System::Memory::{
+    VirtualAlloc, VirtualFree, MEM_COMMIT, MEM_RESERVE, PAGE_READWRITE, VIRTUAL_ALLOCATION_TYPE, PAGE_PROTECTION_FLAGS, MEM_RELEASE
+};
+
+pub struct VirtualBuffer {
+    ptr: NonNull<std::ffi::c_void>,
+    size: usize,
+}
+
+impl VirtualBuffer {
+    pub fn new(size: usize) -> Result<Self, String> {
+        unsafe {
+            let addr = VirtualAlloc(
+                None,
+                size,
+                MEM_COMMIT | MEM_RESERVE,
+                PAGE_READWRITE
+            );
+
+            if addr.is_null() {
+                return Err("VirtualAlloc failed".to_string());
+            }
+
+            Ok(Self {
+                ptr: NonNull::new_unchecked(addr),
+                size,
+            })
+        }
+    }
+
+    // スライスとして安全に露出させる
+    pub fn as_slice_mut(&mut self) -> &mut [u8] {
+        unsafe { std::slice::from_raw_parts_mut(self.ptr.as_ptr() as *mut u8, self.size) }
+    }
+}
+
+impl Drop for VirtualBuffer {
+    fn drop(&mut self) {
+        unsafe {
+            // 第2引数は MEM_RELEASE の場合 0 でなければならない（Win32のルール）
+            let _ = VirtualFree(self.ptr.as_ptr(), 0, MEM_RELEASE);
+            println!("Memory released safely!");
+        }
+    }
+}