Preserve Windows readonly file modes

src/bin/dosh-client.rs

@@ -3811,7 +3811,19 @@ fn mode_for(path: &Path, preserve: bool) -> Result<Option<u32>> {
     }
 }
 
-#[cfg(not(unix))]
+#[cfg(windows)]
+fn mode_for(path: &Path, preserve: bool) -> Result<Option<u32>> {
+    if !preserve {
+        return Ok(None);
+    }
+    let metadata = fs::metadata(path)?;
+    Ok(Some(windows_mode_from_readonly(
+        metadata.is_dir(),
+        metadata.permissions().readonly(),
+    )))
+}
+
+#[cfg(not(any(unix, windows)))]
 fn mode_for(_path: &Path, _preserve: bool) -> Result<Option<u32>> {
     Ok(None)
 }
@@ -3830,11 +3842,40 @@ fn set_local_mode(path: &Path, mode: Option<u32>, preserve: bool) -> Result<()>
     fs::set_permissions(path, permissions).with_context(|| format!("chmod {}", path.display()))
 }
 
-#[cfg(not(unix))]
+#[cfg(windows)]
+fn set_local_mode(path: &Path, mode: Option<u32>, preserve: bool) -> Result<()> {
+    if !preserve {
+        return Ok(());
+    }
+    let Some(mode) = mode else {
+        return Ok(());
+    };
+    let mut permissions = fs::metadata(path)?.permissions();
+    permissions.set_readonly(windows_readonly_from_mode(mode));
+    fs::set_permissions(path, permissions)
+        .with_context(|| format!("set readonly mode {}", path.display()))
+}
+
+#[cfg(not(any(unix, windows)))]
 fn set_local_mode(_path: &Path, _mode: Option<u32>, _preserve: bool) -> Result<()> {
     Ok(())
 }
 
+#[cfg_attr(not(any(test, windows)), allow(dead_code))]
+fn windows_mode_from_readonly(is_dir: bool, readonly: bool) -> u32 {
+    match (is_dir, readonly) {
+        (true, true) => 0o555,
+        (true, false) => 0o777,
+        (false, true) => 0o444,
+        (false, false) => 0o666,
+    }
+}
+
+#[cfg_attr(not(any(test, windows)), allow(dead_code))]
+fn windows_readonly_from_mode(mode: u32) -> bool {
+    mode & 0o222 == 0
+}
+
 fn parse_local_forwards(raw: &[String]) -> Result<Vec<LocalForward>> {
     raw.iter().map(|value| parse_local_forward(value)).collect()
 }
@@ -10100,7 +10141,7 @@ mod tests {
         toml_bare_key_or_quoted, top_trace_events, trace_report_warnings, unix_update_script,
         update_binary_version_for_installer, update_installer_url, update_version_status,
         upsert_managed_block, valid_forward_host, vscode_safe_alias, wake_repaint_retry_deadline,
-        windows_update_script,
+        windows_mode_from_readonly, windows_readonly_from_mode, windows_update_script,
     };
     use dosh::config::{ClientConfig, CommandExtension, HostConfig};
     use dosh::native::EnvVar;
@@ -10186,6 +10227,19 @@ mod tests {
         assert!(local_symlink_target_is_dir(&link, "missing-dir\\"));
     }
 
+    #[test]
+    fn windows_mode_mapping_preserves_readonly_semantics() {
+        assert_eq!(windows_mode_from_readonly(false, true), 0o444);
+        assert_eq!(windows_mode_from_readonly(false, false), 0o666);
+        assert_eq!(windows_mode_from_readonly(true, true), 0o555);
+        assert_eq!(windows_mode_from_readonly(true, false), 0o777);
+
+        assert!(windows_readonly_from_mode(0o444));
+        assert!(windows_readonly_from_mode(0o555));
+        assert!(!windows_readonly_from_mode(0o644));
+        assert!(!windows_readonly_from_mode(0o755));
+    }
+
     #[test]
     fn cleanup_stream_state_removes_all_per_stream_state_only_for_target() {
         let stream_id = 42;