Windows relaunches after an update (#1748)

After the MSI installer finishes, wait for msiexec and start the installed exe; relaunch is detached on Windows.

crates/ui-egui/src/update/install.rs

@@ -107,6 +107,26 @@ pub fn sha256_file(path: &Path) -> Result<String, String> {
     Ok(h.finalize().iter().map(|b| format!("{b:02x}")).collect())
 }
 
+/// The command that runs an installer, waits for it to finish and then starts `exe` (the
+/// installed program), so the app comes back after an update. Windows has no `wait && start` in
+/// a plain process spawn, so PowerShell does the waiting; the installer's exit code is ignored on
+/// purpose: when the user cancels it, the old version is still there to start.
+pub fn relaunch_after(installer: &Path, args: &[String], exe: &Path) -> (PathBuf, Vec<String>) {
+    // PowerShell single-quoted string: only `'` needs doubling.
+    let q = |s: &str| format!("'{}'", s.replace('\'', "''"));
+    // msiexec splits its command line itself, so an argument with spaces needs its own quotes.
+    let list = args.iter().map(|a| if a.contains(' ') { q(&format!("\"{a}\"")) } else { q(a) }).collect::<Vec<_>>().join(",");
+    let script = format!(
+        "Start-Process -FilePath {} -ArgumentList {list} -Wait; Start-Process -FilePath {}",
+        q(&installer.to_string_lossy()),
+        q(&exe.to_string_lossy())
+    );
+    (
+        PathBuf::from("powershell"),
+        vec!["-NoProfile".into(), "-NonInteractive".into(), "-WindowStyle".into(), "Hidden".into(), "-Command".into(), script],
+    )
+}
+
 /// `sums` is signed by `key` (minisign, prehashed) with a trusted comment naming `tag`.
 pub fn verify_signature(sums: &[u8], signature: &str, key: &str, tag: &str) -> Result<(), String> {
     let key = minisign_verify::PublicKey::from_base64(key.trim()).map_err(|e| format!("update signing key: {e}"))?;

crates/ui-egui/src/update/install_tests.rs

@@ -203,3 +203,18 @@ fn installers_and_disk_images_are_handed_over() {
     assert_eq!(apply(&Method::Dmg, &pkg).unwrap(), Outcome::Opened(pkg.clone()));
     let _ = std::fs::remove_dir_all(&dir);
 }
+
+#[test]
+fn windows_installer_is_followed_by_the_new_version() {
+    let args = vec!["/i".to_string(), r"C:\Users\a b\Temp\solidcraft-update\x.msi".to_string(), "/passive".to_string()];
+    let (program, out) = relaunch_after(Path::new("msiexec"), &args, Path::new(r"C:\Program Files\SolidCraft\it's.exe"));
+    assert_eq!(program, PathBuf::from("powershell"));
+    assert_eq!(
+        out.last().unwrap(),
+        &concat!(
+            r#"Start-Process -FilePath 'msiexec' -ArgumentList '/i','"C:\Users\a b\Temp\solidcraft-update\x.msi"','/passive' -Wait; "#,
+            r"Start-Process -FilePath 'C:\Program Files\SolidCraft\it''s.exe'"
+        )
+    );
+    assert!(out.iter().any(|a| a == "-Command"));
+}