Elegantly handle unbounded file symlink resolutions, e.g. 'a' -> 'b' -> 'a/nope'.

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MOS_MIGRATED_REVID=99337668

1 files changed, 50 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/FileSymlinkInfiniteExpansionException.java b/src/main/java/com/google/devtools/build/lib/skyframe/FileSymlinkInfiniteExpansionException.java
new file mode 100644
index 0000000000..a223c8bf7f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/FileSymlinkInfiniteExpansionException.java
@@ -0,0 +1,50 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.skyframe;
+
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.vfs.RootedPath;
+
+/** Exception indicating that a symlink has an unbounded expansion on resolution. */
+public class FileSymlinkInfiniteExpansionException extends FileSymlinkException {
+  private final ImmutableList<RootedPath> pathToChain;
+  private final ImmutableList<RootedPath> chain;
+
+  FileSymlinkInfiniteExpansionException(ImmutableList<RootedPath> pathToChain,
+      ImmutableList<RootedPath> chain) {
+    // The infinite expansion has already been reported by
+    // FileSymlinkInfiniteExpansionUniquenessValue, but we still want to have a readable
+    // #getMessage.
+    super("Infinite symlink expansion");
+    this.pathToChain = pathToChain;
+    this.chain = chain;
+  }
+
+  /**
+   * The symlink path to the symlink that is the root cause of the infinite expansion. For example,
+   * suppose 'a' -> 'b' -> 'c' -> 'd' -> 'c/nope'. The path to the chain is 'a', 'b'.
+   */
+  ImmutableList<RootedPath> getPathToChain() {
+    return pathToChain;
+  }
+
+  /**
+   * The symlink chain that is the root cause of the infinite expansion. For example, suppose
+   * 'a' -> 'b' -> 'c' -> 'd' -> 'c/nope'. The chain is 'c', 'd', 'c/nope'.
+   */
+  ImmutableList<RootedPath> getChain() {
+    return chain;
+  }
+}
+