fix(updates): guard portable builds from installer updates (#550)

src-tauri/src/data_dir.rs

@@ -10,7 +10,7 @@ pub fn resolve_data_dir(default_app_data_dir: PathBuf) -> PathBuf {
 
     #[cfg(target_os = "windows")]
     if let Some(exe_dir) = current_exe_dir() {
-        if exe_dir.join(PORTABLE_MARKER).is_file() {
+        if portable_marker_exists(&exe_dir) {
             return exe_dir.join("data");
         }
     }
@@ -18,11 +18,26 @@ pub fn resolve_data_dir(default_app_data_dir: PathBuf) -> PathBuf {
     default_app_data_dir
 }
 
+#[cfg(target_os = "windows")]
+pub fn is_portable_mode() -> bool {
+    current_exe_dir().is_some_and(|dir| portable_marker_exists(&dir))
+}
+
+#[cfg(not(target_os = "windows"))]
+pub fn is_portable_mode() -> bool {
+    false
+}
+
 #[cfg(target_os = "windows")]
 fn current_exe_dir() -> Option<PathBuf> {
     std::env::current_exe().ok().and_then(|path| path.parent().map(std::path::Path::to_path_buf))
 }
 
+#[cfg(target_os = "windows")]
+fn portable_marker_exists(exe_dir: &std::path::Path) -> bool {
+    exe_dir.join(PORTABLE_MARKER).is_file()
+}
+
 #[cfg(test)]
 fn resolve_data_dir_from_inputs(
     default_app_data_dir: PathBuf,
@@ -40,11 +55,16 @@ fn resolve_data_dir_from_inputs(
     }
 }
 
+#[cfg(test)]
+fn is_portable_mode_from_inputs(exe_dir: Option<PathBuf>, portable_marker_exists: bool) -> bool {
+    exe_dir.is_some() && portable_marker_exists
+}
+
 #[cfg(test)]
 mod tests {
     use std::path::PathBuf;
 
-    use super::resolve_data_dir_from_inputs;
+    use super::{is_portable_mode_from_inputs, resolve_data_dir_from_inputs};
 
     #[test]
     fn uses_portable_data_dir_when_marker_exists() {
@@ -55,4 +75,13 @@ mod tests {
 
         assert_eq!(data_dir, exe_dir.join("data"));
     }
+
+    #[test]
+    fn detects_portable_mode_only_when_marker_exists_next_to_exe() {
+        let exe_dir = PathBuf::from(r"D:\Apps\DBX");
+
+        assert!(is_portable_mode_from_inputs(Some(exe_dir), true));
+        assert!(!is_portable_mode_from_inputs(Some(PathBuf::from(r"D:\Apps\DBX")), false));
+        assert!(!is_portable_mode_from_inputs(None, true));
+    }
 }