1 files changed, 59 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BazelFileSystemModule.java b/src/main/java/com/google/devtools/build/lib/runtime/BazelFileSystemModule.java
new file mode 100644
index 0000000000..d7d6b0a892
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BazelFileSystemModule.java
@@ -0,0 +1,59 @@
+// Copyright 2017 The Bazel Authors. 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.runtime;
+
+import com.google.devtools.build.lib.unix.UnixFileSystem;
+import com.google.devtools.build.lib.util.AbruptExitException;
+import com.google.devtools.build.lib.util.ExitCode;
+import com.google.devtools.build.lib.util.OS;
+import com.google.devtools.build.lib.vfs.FileSystem;
+import com.google.devtools.build.lib.vfs.FileSystem.HashFunction;
+import com.google.devtools.build.lib.vfs.JavaIoFileSystem;
+import com.google.devtools.build.lib.windows.WindowsFileSystem;
+import com.google.devtools.common.options.OptionsParsingException;
+import com.google.devtools.common.options.OptionsProvider;
+
+/**
+ * Module to provide a {@link FileSystem} instance that uses {@code SHA256} as the default hash
+ * function, or else what's specified by {@code -Dbazel.DigestFunction}.
+ *
+ * <p>For legacy reasons we can't make the {@link FileSystem} class use {@code SHA256} by default.
+ */
+public class BazelFileSystemModule extends BlazeModule {
+
+  @Override
+  public FileSystem getFileSystem(OptionsProvider startupOptions) throws AbruptExitException {
+    final HashFunction hashFunction;
+    String value = null;
+    try {
+      value = System.getProperty("bazel.DigestFunction", "MD5");
+      hashFunction = new HashFunction.Converter().convert(value);
+    } catch (OptionsParsingException e) {
+      throw new AbruptExitException(
+          "The specified hash function '" + value + "' is not supported.",
+          ExitCode.COMMAND_LINE_ERROR,
+          e);
+    }
+    if ("0".equals(System.getProperty("io.bazel.EnableJni"))) {
+      // Ignore UnixFileSystem, to be used for bootstrapping.
+      return OS.getCurrent() == OS.WINDOWS
+          ? new WindowsFileSystem(hashFunction)
+          : new JavaIoFileSystem(hashFunction);
+    }
+    // The JNI-based UnixFileSystem is faster, but on Windows it is not available.
+    return OS.getCurrent() == OS.WINDOWS
+        ? new WindowsFileSystem(hashFunction)
+        : new UnixFileSystem(hashFunction);
+  }
+}