fix(fs): do not parse relative paths with a colon as URLs (#3632)

In plugins/fs/src/file_path.rs SafeFilePath::from_str, any string that
parsed as a URL with a scheme of 2+ characters was a URL, so a relative
path such as `notes:2024.txt` became a cannot-be-a-base URL and failed
with InvalidPathUrl.

Cannot-be-a-base URLs are now parsed as paths. The scheme-agnostic
url.to_file_path() stays: its result is scope checked (not a bypass).
Unit test for the parser; e2e spec writes and reads such a file (not on
Windows, where `:` is not allowed in file names).

.changes/fix-fs-url-like-paths.md

@@ -0,0 +1,6 @@
+---
+fs: patch
+fs-js: patch
+---
+
+Fixed relative paths whose first component contains a colon, such as `notes:2024.txt`, being parsed as URLs and rejected with "URL is not a valid path". Only strings with a hierarchical URL form (`scheme://...` or `scheme:/...`) are treated as URLs now.

packages/api-e2e/test/specs/fs.spec.ts

@@ -8,6 +8,7 @@ import {
   tauriError,
   describePlugin,
   itDesktop,
+  itOn,
   scratchDir
 } from '../helpers/index.js'
 
@@ -394,6 +395,25 @@ describePlugin('fs', () => {
     expect(message).toMatch(/resource id \d+ is invalid/)
   })
 
+  // `:` is not allowed in Windows file names
+  itOn(
+    ['linux', 'darwin', 'android', 'ios'],
+    'relative paths that look like a URL scheme are paths',
+    async () => {
+      const result = await tauri(async (api) => {
+        const baseDir = api.fs.BaseDirectory.AppData
+        const path = 'e2e-notes:2024.txt'
+        await api.fs.writeTextFile(path, 'notes', { baseDir })
+        try {
+          return await api.fs.readTextFile(path, { baseDir })
+        } finally {
+          await api.fs.remove(path, { baseDir })
+        }
+      })
+      expect(result).toBe('notes')
+    }
+  )
+
   it('rejects paths outside the configured scope', async () => {
     // `$HOME` itself is not in the example's fs scope (only the app dirs,
     // `$DOWNLOAD` and `$RESOURCE` are).

plugins/fs/src/file_path.rs

@@ -203,7 +203,9 @@ impl FromStr for SafeFilePath {
     type Err = Error;
     fn from_str(s: &str) -> Result<Self> {
         if let Ok(url) = url::Url::from_str(s)
-            && url.scheme().len() != 1
+            // single letter schemes are Windows drive letters, and URLs that cannot be a base
+            // (no `//` nor `/` after the scheme) are relative paths such as `notes:2024.txt`
+            && url.scheme().len() != 1 && !url.cannot_be_a_base()
         {
             return Ok(Self::Url(url));
         }
@@ -306,3 +308,39 @@ impl TryFrom<FilePath> for SafeFilePath {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use super::SafeFilePath;
+
+    #[test]
+    fn safe_file_path_from_str() {
+        for url in [
+            "file:///C:/Users",
+            "file:///home/user/file.txt",
+            "content://com.android.providers/document/1",
+            "asset://localhost/file.txt",
+        ] {
+            assert!(
+                matches!(SafeFilePath::from_str(url), Ok(SafeFilePath::Url(_))),
+                "{url}"
+            );
+        }
+
+        for path in [
+            "C:/Users",
+            "C:\\Users",
+            "notes:2024.txt",
+            "ab:c",
+            "dir/file.txt",
+            "/home/user/file.txt",
+        ] {
+            assert!(
+                matches!(SafeFilePath::from_str(path), Ok(SafeFilePath::Path(_))),
+                "{path}"
+            );
+        }
+    }
+}