Fix exception after removing last relative component (#4011)

dart-lang · Sep 8, 2023 · cb0d6f9 · cb0d6f9
1 parent 1e38c83
commit cb0d6f9
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Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/lib/src/io.dart b/lib/src/io.dart
@@ -148,7 +148,7 @@ String canonicalize(String pathString) {
 
     // Pop directories off `newPath` if the component links upwards in the
     // directory hierarchy.
-    while (relativeComponents.first == '..') {
+    while (relativeComponents.firstOrNull == '..') {
       newPath = path.dirname(newPath);
       relativeComponents.removeFirst();
     }

diff --git a/test/io_test.dart b/test/io_test.dart
@@ -150,6 +150,25 @@ void main() {
       );
     });
 
+    test('resolves a symlink to parent', () {
+      expect(
+        _withCanonicalTempDir((temp) {
+          _createDir(path.join(temp, 'linked-dir'));
+          _createDir(path.join(temp, 'linked-dir', 'a'));
+          _createDir(path.join(temp, 'linked-dir', 'b'));
+          createSymlink(
+            path.join(temp, 'linked-dir'),
+            path.join(temp, 'linked-dir', 'a', 'symlink'),
+          );
+          expect(
+            canonicalize(path.join(temp, 'linked-dir', 'a', 'symlink', 'b')),
+            equals(path.join(temp, 'linked-dir', 'b')),
+          );
+        }),
+        completes,
+      );
+    });
+
     test('resolves a relative symlink', () {
       expect(
         _withCanonicalTempDir((temp) {