Implements repository_ctx.os

repository_ctx.os gives access to os related information:
   - .system returns the name of the current platform.
   - .environ returns the list of environment variables.

Issue #893: Step 4 of http://goo.gl/OZV3o0. See http://goo.gl/fD4ZsY.

--
MOS_MIGRATED_REVID=115337406

5 files changed, 95 insertions, 5 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index c9ed05fb45..8a1eb0da79 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -601,6 +601,7 @@ java_library(
         ":concurrent",
         ":events",
         ":maven-connector",
+        ":runtime",
         ":util",
         "//src/java_tools/singlejar/java/com/google/devtools/build/zip",
         "//src/main/java/com/google/devtools/build/lib:build-base",
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
index dab80039c6..5e16483f6a 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
@@ -55,8 +55,11 @@ import com.google.devtools.build.lib.rules.repository.RepositoryFunction;
 import com.google.devtools.build.lib.rules.repository.RepositoryLoaderFunction;
 import com.google.devtools.build.lib.runtime.BlazeCommand;
 import com.google.devtools.build.lib.runtime.BlazeModule;
+import com.google.devtools.build.lib.runtime.Command;
+import com.google.devtools.build.lib.runtime.CommandEnvironment;
 import com.google.devtools.build.lib.skyframe.SkyFunctions;
 import com.google.devtools.build.lib.skyframe.SkyValueDirtinessChecker;
+import com.google.devtools.build.lib.util.AbruptExitException;
 import com.google.devtools.build.lib.util.Clock;
 import com.google.devtools.build.lib.util.io.TimestampGranularityMonitor;
 import com.google.devtools.build.skyframe.SkyFunction;
@@ -79,6 +82,8 @@ public class BazelRepositoryModule extends BlazeModule {
   // A map of repository handlers that can be looked up by rule class name.
   private final ImmutableMap<String, RepositoryFunction> repositoryHandlers;
   private final AtomicBoolean isFetch = new AtomicBoolean(false);
+  private final SkylarkRepositoryFunction skylarkRepositoryFunction =
+      new SkylarkRepositoryFunction();
 
   public BazelRepositoryModule() {
     repositoryHandlers =
@@ -177,8 +182,13 @@ public class BazelRepositoryModule extends BlazeModule {
     builder.put(
         SkyFunctions.REPOSITORY_DIRECTORY,
         new RepositoryDelegatorFunction(
-            directories, repositoryHandlers, new SkylarkRepositoryFunction(), isFetch));
+            directories, repositoryHandlers, skylarkRepositoryFunction, isFetch));
     builder.put(MavenServerFunction.NAME, new MavenServerFunction(directories));
     return builder.build();
   }
+
+  @Override
+  public void beforeCommand(Command command, CommandEnvironment env) throws AbruptExitException {
+    skylarkRepositoryFunction.setCommandEnvironment(env);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkOS.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkOS.java
new file mode 100644
index 0000000000..fd51059137
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkOS.java
@@ -0,0 +1,53 @@
+// 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.bazel.repository.skylark;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+
+import java.util.Map;
+
+/**
+ * A Skylark structure to deliver information about the system we are running on.
+ */
+@Immutable
+@SkylarkModule(
+  name = "repository_os",
+  doc = "Various data about the current platform Bazel is running on."
+)
+final class SkylarkOS {
+
+  private final ImmutableMap<String, String> environ;
+
+  SkylarkOS(Map<String, String> environ) {
+    this.environ = ImmutableMap.copyOf(environ);
+  }
+
+  @SkylarkCallable(name = "environ", structField = true, doc = "The list of environment variables.")
+  public ImmutableMap<String, String> getEnviron() {
+    return environ;
+  }
+
+  @SkylarkCallable(
+    name = "name",
+    structField = true,
+    doc = "A string identifying the current system Bazel is running on."
+  )
+  public String getName() {
+    return System.getProperty("os.name").toLowerCase();
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
index b51b01c9cb..04a868b9d0 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
@@ -35,6 +35,7 @@ import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
 import java.io.File;
 import java.io.IOException;
 import java.util.List;
+import java.util.Map;
 
 /**
  * Skylark API for the repository_rule's context.
@@ -52,6 +53,7 @@ public class SkylarkRepositoryContext {
   private final Rule rule;
   private final Path outputDirectory;
   private final SkylarkClassObject attrObject;
+  private final SkylarkOS osObject;
 
   /**
    * In native code, private values start with $. In Skylark, private values start with _, because
@@ -65,12 +67,12 @@ public class SkylarkRepositoryContext {
   }
 
   /**
-   * Create a new context (ctx) object for a skylark repository rule ({@code rule} argument). The
-   * environment
+   * Create a new context (ctx) object for a skylark repository rule ({@code rule} argument).
    */
-  SkylarkRepositoryContext(Rule rule, Path outputDirectory) {
+  SkylarkRepositoryContext(Rule rule, Path outputDirectory, Map<String, String> env) {
     this.rule = rule;
     this.outputDirectory = outputDirectory;
+    this.osObject = new SkylarkOS(env);
     AggregatingAttributeMapper attrs = AggregatingAttributeMapper.of(rule);
     ImmutableMap.Builder<String, Object> attrBuilder = new ImmutableMap.Builder<>();
     for (String name : attrs.getAttributeNames()) {
@@ -132,6 +134,15 @@ public class SkylarkRepositoryContext {
   }
 
   @SkylarkCallable(
+    name = "os",
+    structField = true,
+    doc = "A struct to access information from the system "
+  )
+  public SkylarkOS getOS() {
+    return osObject;
+  }
+
+  @SkylarkCallable(
     name = "execute",
     doc =
         "Executes the command given by the list of arguments. The execution time of the command"
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
index 51bbe832f3..9c9a777610 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
@@ -20,6 +20,7 @@ import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.rules.repository.RepositoryDirectoryValue;
 import com.google.devtools.build.lib.rules.repository.RepositoryFunction;
+import com.google.devtools.build.lib.runtime.CommandEnvironment;
 import com.google.devtools.build.lib.skyframe.FileValue;
 import com.google.devtools.build.lib.syntax.BaseFunction;
 import com.google.devtools.build.lib.syntax.EvalException;
@@ -32,6 +33,7 @@ import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
 import com.google.devtools.build.skyframe.SkyValue;
 
 import java.io.IOException;
+import java.util.Map;
 
 import javax.annotation.Nullable;
 
@@ -39,6 +41,19 @@ import javax.annotation.Nullable;
  * A repository function to delegate work done by skylark remote repositories.
  */
 public class SkylarkRepositoryFunction extends RepositoryFunction {
+
+  private CommandEnvironment commandEnvironment = null;
+
+  public void setCommandEnvironment(CommandEnvironment commandEnvironment) {
+    this.commandEnvironment = commandEnvironment;
+  }
+
+  private Map<String, String> getClientEnvironment() {
+    return commandEnvironment != null
+        ? commandEnvironment.getClientEnv()
+        : ImmutableMap.<String, String>of();
+  }
+
   @Nullable
   @Override
   public SkyValue fetch(Rule rule, Path outputDirectory, Environment env)
@@ -52,7 +67,7 @@ public class SkylarkRepositoryFunction extends RepositoryFunction {
               .setEventHandler(env.getListener())
               .build();
       SkylarkRepositoryContext skylarkRepositoryContext =
-          new SkylarkRepositoryContext(rule, outputDirectory);
+          new SkylarkRepositoryContext(rule, outputDirectory, getClientEnvironment());
       // This has side-effect, we don't care about the output.
       // Also we do a lot of stuff in there, maybe blocking operations and we should certainly make
       // it possible to return null and not block but it doesn't seem to be easy with Skylark