Load JNI library on Windows from the runfiles tree as a fallback

This is the behavior of the UnixJniLoader. In order to do that, this
change also moved the runfiles support on Windows in its own library
that the WindowsJniLoader can use to load the JNI library from tests.

Also add the JNI library on Windows to all test that use the JNI library
on Unix.

Fixes #2300.

--
Change-Id: I2eb9207c3aa310d95912a48f64f676957c47cd34
Reviewed-on: https://cr.bazel.build/8045
PiperOrigin-RevId: 143114397
MOS_MIGRATED_REVID=143114397

2 files changed, 79 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/windows/WindowsJniLoader.java b/src/main/java/com/google/devtools/build/lib/windows/WindowsJniLoader.java
index 2fe564e678..6f42c1cf7f 100644
--- a/src/main/java/com/google/devtools/build/lib/windows/WindowsJniLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/windows/WindowsJniLoader.java
@@ -14,6 +14,8 @@
 
 package com.google.devtools.build.lib.windows;
 
+import java.io.IOException;
+
 /**
  * Loads native code under Windows.
  */
@@ -24,7 +26,17 @@ public class WindowsJniLoader {
       return;
     }
 
-    System.loadLibrary("windows_jni");
+    try {
+      System.loadLibrary("windows_jni");
+    } catch (UnsatisfiedLinkError ex) {
+      // We are probably in tests, let's try to find the library in the runfiles
+      try {
+        System.load(WindowsRunfiles.getRunfile("io_bazel/src/main/native/windows_jni.dll"));
+      } catch (IOException e) {
+        // We throw the UnsatisfiedLinkError if we cannot find the runfiles
+        throw ex;
+      }
+    }
     jniLoaded = true;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/windows/WindowsRunfiles.java b/src/main/java/com/google/devtools/build/lib/windows/WindowsRunfiles.java
new file mode 100644
index 0000000000..876531073a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/windows/WindowsRunfiles.java
@@ -0,0 +1,66 @@
+// Copyright 2016 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.windows;
+
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.Map;
+
+/** Utility class for getting runfiles in tests on Windows. */
+public final class WindowsRunfiles {
+
+  private static Map<String, String> runfiles;
+
+  /**
+   * Returns the actual path on the system corresponding to a given runfiles path. On Unix-like with
+   * the symlink tree, this function could just returns the runfiles path and let the symlinks do
+   * the actual resolution.
+   */
+  public static String getRunfile(String runfilesPath) throws IOException {
+    ensureRunfilesParsed();
+    return runfiles.get(runfilesPath);
+  }
+
+  private static synchronized void ensureRunfilesParsed() throws IOException {
+    if (runfiles != null) {
+      return;
+    }
+
+    runfiles = new HashMap<>();
+    InputStream fis = new FileInputStream(System.getenv("RUNFILES_MANIFEST_FILE"));
+    InputStreamReader isr = new InputStreamReader(fis, Charset.forName("UTF-8"));
+    try (BufferedReader br = new BufferedReader(isr)) {
+      String line;
+      while ((line = br.readLine()) != null) {
+        line = line.trim();
+        if (!line.isEmpty()) {
+          // TODO(bazel-team): This is buggy when the path contains spaces, we should fix the
+          // manifest format.
+          String[] splitLine = line.split(" ");
+          if (splitLine.length != 2) {
+            throw new IllegalStateException("Runfiles manifest entry contains more than one space");
+          }
+
+          runfiles.put(splitLine[0], splitLine[1]);
+        }   
+      }
+    }
+  }
+}