Embed longPathAware manifest in the Windows executable

youknowone · youknowone · commit a544b7d4f835 · 2026-07-09T21:54:19.000+09:00
The Windows binary now embeds an application manifest declaring
longPathAware, so the Win32 APIs handle paths longer than MAX_PATH and a
path component exceeding the 255-char limit is reported as EINVAL instead
of the whole path being rejected for length (ENOENT). The manifest is now
compiled even when logo.ico is absent.
diff --git a/build.rs b/build.rs
@@ -12,11 +12,14 @@ fn main() {
         "windows" => {
             println!("cargo:rerun-if-changed=logo.ico");
             let mut res = winresource::WindowsResource::new();
+            // Opt into long path support so paths longer than MAX_PATH (260) are
+            // handled by the Win32 APIs, and a path component over the 255-char
+            // limit is reported as EINVAL rather than being rejected for length.
+            res.set_manifest(WINDOWS_MANIFEST);
             if std::path::Path::new("logo.ico").exists() {
                 res.set_icon("logo.ico");
             } else {
                 println!("cargo:warning=logo.ico not found, skipping icon embedding");
-                return;
             }
             res.compile()
                 .map_err(|e| {
@@ -27,3 +30,21 @@ fn main() {
         _ => {}
     }
 }
+
+/// Application manifest embedded into the Windows executable.
+const WINDOWS_MANIFEST: &str = r#"<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
+    <security>
+      <requestedPrivileges>
+        <requestedExecutionLevel level="asInvoker" uiAccess="false"/>
+      </requestedPrivileges>
+    </security>
+  </trustInfo>
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <longPathAware xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">true</longPathAware>
+    </windowsSettings>
+  </application>
+</assembly>
+"#;
