Fix listing directories with recursive symlinks.

sdk/lib/_internal/pub/lib/src/io.dart

Index: sdk/lib/_internal/pub/lib/src/io.dart
diff --git a/sdk/lib/_internal/pub/lib/src/io.dart b/sdk/lib/_internal/pub/lib/src/io.dart
index 1620837c2b2f3362997abbf78ac581a52b543dab..0c45b33ad02cf552107e13dd3750647950d621a9 100644
--- a/sdk/lib/_internal/pub/lib/src/io.dart
+++ b/sdk/lib/_internal/pub/lib/src/io.dart
@@ -133,16 +133,9 @@ String createTempDir([dir = '']) {
 /// The returned paths are guaranteed to begin with [dir].
 List<String> listDir(String dir, {bool recursive: false,
     bool includeHidden: false}) {
-  List<String> doList(String dir, Set<String> listedDirectories) {
+  Set<String> visited = new Set<String>();
+  List<String> doList(String dir) {
     var contents = <String>[];
-
-    // Avoid recursive symlinks.
-    var resolvedPath = new File(dir).fullPathSync();
-    if (listedDirectories.contains(resolvedPath)) return [];
-
-    listedDirectories = new Set<String>.from(listedDirectories);
-    listedDirectories.add(resolvedPath);
-
     log.io("Listing directory $dir.");
 
     var children = <String>[];

[Andrei Mouravski, 2013/05/02 00:16:13]

Why not reuse contents instead of making children?

[Bob Nystrom, 2013/05/02 00:18:59]

I'm not exactly sure, but I believe the existed code separates those out to
control the order of the returned items. By adding children at the end, it puts
all directories before any subdirectories.

@@ -151,14 +144,23 @@ List<String> listDir(String dir, {bool recursive: false,
         continue;
       }
 
+      // Filter out duplicate entries caused by recursive symlinks. We check
+      // for duplicate entities instead of looking for the symlink cycle itself
+      // because [identicalSync] does not consider a link identical to its
+      // target. That means a directory and the recursive symlink to it will
+      // show up as different entities.
+      if (visited.any((previous) =>
+          FileSystemEntity.identicalSync(previous, entity.path))) {
+        continue;
+      }
+      visited.add(entity.path);
+
       contents.add(entity.path);
       if (entity is Directory) {
         // TODO(nweiz): don't manually recurse once issue 4794 is fixed.
         // Note that once we remove the manual recursion, we'll need to
         // explicitly filter out files in hidden directories.
-        if (recursive) {
-          children.addAll(doList(entity.path, listedDirectories));
-        }
+        if (recursive) children.addAll(doList(entity.path));
       }
     }
 
@@ -167,7 +169,7 @@ List<String> listDir(String dir, {bool recursive: false,
     return contents;
   }
 
-  return doList(dir, new Set<String>());
+  return doList(dir);
 }
 
 /// Returns whether [dir] exists on the file system. This will return `true` for