Add export support

src/utils/encoding_win.rs

@@ -0,0 +1,121 @@
+use windows_sys::Win32::Foundation::GetLastError;
+use windows_sys::Win32::Globalization::{MB_ERR_INVALID_CHARS, MultiByteToWideChar, WideCharToMultiByte};
+
+#[derive(Debug)]
+pub struct WinError {
+    pub code: u32,
+}
+
+impl WinError {
+    pub fn new(code: u32) -> Self {
+        WinError { code }
+    }
+
+    pub fn from_last_error() -> Self {
+        let code = unsafe { GetLastError() };
+        WinError::new(code)
+    }
+}
+
+impl std::error::Error for WinError {}
+
+impl std::fmt::Display for WinError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Windows error code: {}", self.code)
+    }
+}
+
+pub fn decode_to_string(cp: u32, data: &[u8]) -> Result<String, WinError> {
+    let needed_len = unsafe {
+        MultiByteToWideChar(
+            cp,
+            MB_ERR_INVALID_CHARS,
+            data.as_ptr() as _,
+            data.len() as i32,
+            std::ptr::null_mut(),
+            0,
+        )
+    };
+    if needed_len == 0 {
+        return Err(WinError::from_last_error());
+    }
+    let mut wc = Vec::with_capacity(needed_len as usize);
+    wc.resize(needed_len as usize, 0);
+    let result = unsafe {
+        MultiByteToWideChar(
+            cp,
+            MB_ERR_INVALID_CHARS,
+            data.as_ptr() as _,
+            data.len() as i32,
+            wc.as_mut_ptr(),
+            needed_len,
+        )
+    };
+    if result == 0 {
+        return Err(WinError::from_last_error());
+    }
+    Ok(String::from_utf16_lossy(&wc))
+}
+
+pub fn encode_string(cp: u32, data: &str) -> Result<Vec<u8>, WinError> {
+    let wstr = data.encode_utf16().collect::<Vec<u16>>();
+    let needed_len = unsafe {
+        WideCharToMultiByte(
+            cp,
+            0,
+            wstr.as_ptr(),
+            wstr.len() as i32,
+            std::ptr::null_mut(),
+            0,
+            std::ptr::null_mut(),
+            std::ptr::null_mut(),
+        )
+    };
+    if needed_len == 0 {
+        return Err(WinError::from_last_error());
+    }
+    let mut mb = Vec::with_capacity(needed_len as usize);
+    mb.resize(needed_len as usize, 0);
+    let result = unsafe {
+        WideCharToMultiByte(
+            cp,
+            0,
+            wstr.as_ptr(),
+            wstr.len() as i32,
+            mb.as_mut_ptr(),
+            needed_len,
+            std::ptr::null_mut(),
+            std::ptr::null_mut(),
+        )
+    };
+    if result == 0 {
+        return Err(WinError::from_last_error());
+    }
+    Ok(mb)
+}
+
+#[test]
+fn test_decode_to_string() {
+    assert_eq!(
+        decode_to_string(
+            65001,
+            &[228, 184, 173, 230, 150, 135, 230, 181, 139, 232, 175, 149]
+        )
+        .unwrap(),
+        "中文测试".to_string()
+    );
+    assert_eq!(
+        decode_to_string(
+            932,
+            &[
+                130, 171, 130, 225, 130, 215, 130, 194, 130, 187, 130, 211, 130, 198
+            ]
+        )
+        .unwrap(),
+        "きゃべつそふと".to_string()
+    );
+    assert_eq!(
+        decode_to_string(936, &[214, 208, 206, 196]).unwrap(),
+        "中文".to_string()
+    );
+}