Make android_sdk_repository build_tools_version attribute optional.

If none is specified, the highest version installed in <sdk>/build-tools/ will
be used.

RELNOTES: android_sdk_repository build_tools_version is now optional. The
highest installed build-tools will be used if none is specified.

--
PiperOrigin-RevId: 142490569
MOS_MIGRATED_REVID=142490569

2 files changed, 81 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryFunction.java
index d609c2276b..f031d69b53 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryFunction.java
@@ -24,12 +24,16 @@ import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
 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.skyframe.DirectoryListingValue;
+import com.google.devtools.build.lib.skyframe.Dirents;
 import com.google.devtools.build.lib.skyframe.FileSymlinkException;
 import com.google.devtools.build.lib.skyframe.FileValue;
 import com.google.devtools.build.lib.skyframe.InconsistentFilesystemException;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.Type;
 import com.google.devtools.build.lib.util.ResourceFileLoader;
+import com.google.devtools.build.lib.vfs.Dirent;
+import com.google.devtools.build.lib.vfs.FileSystem;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.lib.vfs.RootedPath;
@@ -46,6 +50,7 @@ import javax.annotation.Nullable;
  * Implementation of the {@code android_sdk_repository} rule.
  */
 public class AndroidSdkRepositoryFunction extends RepositoryFunction {
+  private static final String BUILD_TOOLS_DIR_NAME = "build-tools";
   private static final Revision MIN_BUILD_TOOLS_REVISION = new Revision(24, 0, 3);
 
   @Override
@@ -67,8 +72,21 @@ public class AndroidSdkRepositoryFunction extends RepositoryFunction {
     }
 
     AttributeMap attributes = NonconfigurableAttributeMapper.of(rule);
-    String buildToolsDirectory = attributes.get("build_tools_version", Type.STRING);
     Integer apiLevel = attributes.get("api_level", Type.INTEGER);
+    String buildToolsDirectory;
+    if (attributes.isAttributeValueExplicitlySpecified("build_tools_version")) {
+      buildToolsDirectory = attributes.get("build_tools_version", Type.STRING);
+    } else {
+      // If the build_tools_version attribute is not explicitly set, we select the highest version
+      // installed in the SDK.
+      DirectoryListingValue directoryValue =
+          getBuildToolsDirectoryListing(
+              directories.getOutputBase().getFileSystem(), pathFragment, env);
+      if (directoryValue == null) {
+        return null;
+      }
+      buildToolsDirectory = getNewestBuildToolsDirectory(rule, directoryValue.getDirents());
+    }
 
     // android_sdk_repository.build_tools_version is technically actually the name of the
     // directory in $sdk/build-tools. Most of the time this is just the actual build tools
@@ -142,6 +160,64 @@ public class AndroidSdkRepositoryFunction extends RepositoryFunction {
     }
   }
 
+  /**
+   * Gets a DirectoryListingValue for the build-tools directory under the sdkRepoPathFragment
+   * or returns null.
+   */
+  private static DirectoryListingValue getBuildToolsDirectoryListing(
+      FileSystem fs, PathFragment sdkRepoPathFragment, Environment env)
+      throws RepositoryFunctionException, InterruptedException {
+    try {
+      return (DirectoryListingValue)
+          env.getValueOrThrow(
+              DirectoryListingValue.key(
+                  RootedPath.toRootedPath(
+                      fs.getRootDirectory(),
+                      fs.getPath(sdkRepoPathFragment).getChild(BUILD_TOOLS_DIR_NAME))),
+              InconsistentFilesystemException.class);
+    } catch (InconsistentFilesystemException e) {
+      throw new RepositoryFunctionException(new IOException(e), Transience.PERSISTENT);
+    }
+  }
+
+  /**
+   * Gets the newest build tools directory according to {@link Revision}.
+   *
+   * @throws RepositoryFunctionException if none of the buildToolsDirectories are directories and
+   *     have names that are parsable as build tools version.
+   */
+  private static String getNewestBuildToolsDirectory(Rule rule, Dirents buildToolsDirectories)
+      throws RepositoryFunctionException {
+    String newestBuildToolsDirectory = null;
+    Revision newestBuildToolsRevision = null;
+    for (Dirent buildToolsDirectory : buildToolsDirectories) {
+      if (buildToolsDirectory.getType() != Dirent.Type.DIRECTORY) {
+        continue;
+      }
+      try {
+        Revision buildToolsRevision = Revision.parseRevision(buildToolsDirectory.getName());
+        if (newestBuildToolsRevision == null
+            || buildToolsRevision.compareTo(newestBuildToolsRevision) > 0) {
+          newestBuildToolsDirectory = buildToolsDirectory.getName();
+          newestBuildToolsRevision = buildToolsRevision;
+        }
+      } catch (NumberFormatException e) {
+        // Ignore unparsable build tools directories.
+      }
+    }
+    if (newestBuildToolsDirectory == null) {
+      throw new RepositoryFunctionException(
+          new EvalException(
+              rule.getLocation(),
+              String.format(
+                  "Bazel requires Android build tools version %s or newer but none are installed. "
+                      + "Please install a recent version through the Android SDK manager.",
+                  MIN_BUILD_TOOLS_REVISION)),
+          Transience.PERSISTENT);
+    }
+    return newestBuildToolsDirectory;
+  }
+
   private static Properties getBuildToolsSourceProperties(
       Path directory, String buildToolsDirectory, Environment env)
       throws RepositoryFunctionException, InterruptedException {
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryRule.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryRule.java
index 75968bcb84..d87f4602e9 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryRule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidSdkRepositoryRule.java
@@ -63,7 +63,10 @@ public class AndroidSdkRepositoryRule implements RuleDefinition {
         // actually "x.y.z-rcN". E.g., for 24, the directory is "$sdk/build-tools/24.0.0-preview",
         // but the version is e.g. "24 rc3". The android_sdk rule that is generated from
         // android_sdk_repository would need the real version ("24 rc3").
-        .add(attr("build_tools_version", STRING).mandatory().nonconfigurable("WORKSPACE rule"))
+        //
+        // If build_tools_version is not specified explicitly, the highest build tools version
+        // installed will be used.
+        .add(attr("build_tools_version", STRING).nonconfigurable("WORKSPACE rule"))
         .add(attr("api_level", INTEGER).mandatory().nonconfigurable("WORKSPACE rule"))
         .build();
   }