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diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/FileValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/FileValue.java
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+++ b/src/main/java/com/google/devtools/build/lib/skyframe/FileValue.java
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+// Copyright 2014 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.base.Preconditions;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+import com.google.devtools.build.lib.skyframe.FileStateValue.Type;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.build.lib.vfs.RootedPath;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+
+import java.util.Objects;
+
+import javax.annotation.Nullable;
+
+/**
+ * A value that corresponds to a file (or directory or symlink or non-existent file), fully
+ * accounting for symlinks (e.g. proper dependencies on ancestor symlinks so as to be incrementally
+ * correct). Anything in Skyframe that cares about the fully resolved path of a file (e.g. anything
+ * that cares about the contents of a file) should have a dependency on the corresponding
+ * {@link FileValue}.
+ *
+ * <p>
+ * Note that the existence of a file value does not imply that the file exists on the filesystem.
+ * File values for missing files will be created on purpose in order to facilitate incremental
+ * builds in the case those files have reappeared.
+ *
+ * <p>
+ * This class contains the relevant metadata for a file, although not the contents. Note that
+ * since a FileValue doesn't store its corresponding SkyKey, it's possible for the FileValues for
+ * two different paths to be the same.
+ *
+ * <p>
+ * This should not be used for build outputs; use {@link ArtifactValue} for those.
+ */
+@Immutable
+@ThreadSafe
+public abstract class FileValue implements SkyValue {
+
+  boolean exists() {
+    return realFileStateValue().getType() != Type.NONEXISTENT;
+  }
+
+  public boolean isSymlink() {
+    return false;
+  }
+
+  /**
+   * Returns true if this value corresponds to a file or symlink to an existing file. If so, its
+   * parent directory is guaranteed to exist.
+   */
+  public boolean isFile() {
+    return realFileStateValue().getType() == Type.FILE;
+  }
+
+  /**
+   * Returns true if the file is a directory or a symlink to an existing directory. If so, its
+   * parent directory is guaranteed to exist.
+   */
+  public boolean isDirectory() {
+    return realFileStateValue().getType() == Type.DIRECTORY;
+  }
+
+  /**
+   * Returns the real rooted path of the file, taking ancestor symlinks into account. For example,
+   * the rooted path ['root']/['a/b'] is really ['root']/['c/b'] if 'a' is a symlink to 'b'. Note
+   * that ancestor symlinks outside the root boundary are not taken into consideration.
+   */
+  public abstract RootedPath realRootedPath();
+
+  abstract FileStateValue realFileStateValue();
+
+  /**
+   * Returns the unresolved link target if {@link #isSymlink()}.
+   *
+   * <p>This is useful if the caller wants to, for example, duplicate a relative symlink. An actual
+   * example could be a build rule that copies a set of input files to the output directory, but
+   * upon encountering symbolic links it can decide between copying or following them.
+   */
+  PathFragment getUnresolvedLinkTarget() {
+    throw new IllegalStateException(this.toString());
+  }
+
+  long getSize() {
+    Preconditions.checkState(isFile(), this);
+    return realFileStateValue().getSize();
+  }
+
+  @Nullable
+  byte[] getDigest() {
+    Preconditions.checkState(isFile(), this);
+    return realFileStateValue().getDigest();
+  }
+
+  /**
+   * Returns a key for building a file value for the given root-relative path.
+   */
+  @ThreadSafe
+  public static SkyKey key(RootedPath rootedPath) {
+    return new SkyKey(SkyFunctions.FILE, rootedPath);
+  }
+
+  /**
+   * Only intended to be used by {@link FileFunction}. Should not be used for symlink cycles.
+   */
+  static FileValue value(RootedPath rootedPath, FileStateValue fileStateValue,
+      RootedPath realRootedPath, FileStateValue realFileStateValue) {
+    if (rootedPath.equals(realRootedPath)) {
+      Preconditions.checkState(fileStateValue.getType() != FileStateValue.Type.SYMLINK,
+          "rootedPath: %s, fileStateValue: %s, realRootedPath: %s, realFileStateValue: %s",
+          rootedPath, fileStateValue, realRootedPath, realFileStateValue);
+      return new RegularFileValue(rootedPath, fileStateValue);
+    } else {
+      if (fileStateValue.getType() == FileStateValue.Type.SYMLINK) {
+        return new SymlinkFileValue(realRootedPath, realFileStateValue,
+            fileStateValue.getSymlinkTarget());
+      } else {
+        return new DifferentRealPathFileValue(realRootedPath, realFileStateValue);
+      }
+    }
+  }
+
+  /**
+   * Implementation of {@link FileValue} for files whose fully resolved path is the same as the
+   * requested path. For example, this is the case for the path "foo/bar/baz" if neither 'foo' nor
+   * 'foo/bar' nor 'foo/bar/baz' are symlinks.
+   */
+  private static final class RegularFileValue extends FileValue {
+
+    private final RootedPath rootedPath;
+    private final FileStateValue fileStateValue;
+
+    private RegularFileValue(RootedPath rootedPath, FileStateValue fileState) {
+      this.rootedPath = Preconditions.checkNotNull(rootedPath);
+      this.fileStateValue = Preconditions.checkNotNull(fileState);
+    }
+
+    @Override
+    public RootedPath realRootedPath() {
+      return rootedPath;
+    }
+
+    @Override
+    FileStateValue realFileStateValue() {
+      return fileStateValue;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null) {
+        return false;
+      }
+      if (obj.getClass() != RegularFileValue.class) {
+        return false;
+      }
+      RegularFileValue other = (RegularFileValue) obj;
+      return rootedPath.equals(other.rootedPath) && fileStateValue.equals(other.fileStateValue);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(rootedPath, fileStateValue);
+    }
+
+    @Override
+    public String toString() {
+      return rootedPath + ", " + fileStateValue;
+    }
+  }
+
+  /**
+   * Base class for {@link FileValue}s for files whose fully resolved path is different than the
+   * requested path. For example, this is the case for the path "foo/bar/baz" if at least one of
+   * 'foo', 'foo/bar', or 'foo/bar/baz' is a symlink.
+   */
+  private static class DifferentRealPathFileValue extends FileValue {
+
+    protected final RootedPath realRootedPath;
+    protected final FileStateValue realFileStateValue;
+
+    private DifferentRealPathFileValue(RootedPath realRootedPath,
+        FileStateValue realFileStateValue) {
+      this.realRootedPath = Preconditions.checkNotNull(realRootedPath);
+      this.realFileStateValue = Preconditions.checkNotNull(realFileStateValue);
+    }
+
+    @Override
+    public RootedPath realRootedPath() {
+      return realRootedPath;
+    }
+
+    @Override
+    FileStateValue realFileStateValue() {
+      return realFileStateValue;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null) {
+        return false;
+      }
+      if (obj.getClass() != DifferentRealPathFileValue.class) {
+        return false;
+      }
+      DifferentRealPathFileValue other = (DifferentRealPathFileValue) obj;
+      return realRootedPath.equals(other.realRootedPath)
+          && realFileStateValue.equals(other.realFileStateValue);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(realRootedPath, realFileStateValue);
+    }
+
+    @Override
+    public String toString() {
+      return realRootedPath + ", " + realFileStateValue + " (symlink ancestor)";
+    }
+  }
+
+  /** Implementation of {@link FileValue} for files that are symlinks. */
+  private static final class SymlinkFileValue extends DifferentRealPathFileValue {
+    private final PathFragment linkValue;
+
+    private SymlinkFileValue(RootedPath realRootedPath, FileStateValue realFileState,
+        PathFragment linkTarget) {
+      super(realRootedPath, realFileState);
+      this.linkValue = linkTarget;
+    }
+
+    @Override
+    public boolean isSymlink() {
+      return true;
+    }
+
+    @Override
+    public PathFragment getUnresolvedLinkTarget() {
+      return linkValue;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null) {
+        return false;
+      }
+      if (obj.getClass() != SymlinkFileValue.class) {
+        return false;
+      }
+      SymlinkFileValue other = (SymlinkFileValue) obj;
+      return realRootedPath.equals(other.realRootedPath)
+          && realFileStateValue.equals(other.realFileStateValue)
+          && linkValue.equals(other.linkValue);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(realRootedPath, realFileStateValue, linkValue, Boolean.TRUE);
+    }
+
+    @Override
+    public String toString() {
+      return String.format("symlink (real_path=%s, real_state=%s, link_value=%s)",
+          realRootedPath, realFileStateValue, linkValue);
+    }
+  }
+}