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Diffstat (limited to 'java/com/google/devtools/build/android/desugar/scan/KeepScanner.java')
| -rw-r--r-- | java/com/google/devtools/build/android/desugar/scan/KeepScanner.java | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/java/com/google/devtools/build/android/desugar/scan/KeepScanner.java b/java/com/google/devtools/build/android/desugar/scan/KeepScanner.java new file mode 100644 index 0000000..4924f7c --- /dev/null +++ b/java/com/google/devtools/build/android/desugar/scan/KeepScanner.java @@ -0,0 +1,303 @@ +// Copyright 2018 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.android.desugar.scan; + +import static com.google.common.base.Preconditions.checkArgument; +import static com.google.common.base.Preconditions.checkNotNull; +import static com.google.common.base.Preconditions.checkState; +import static java.nio.file.StandardOpenOption.CREATE; +import static java.util.Comparator.comparing; + +import com.google.common.collect.ImmutableList; +import com.google.common.collect.ImmutableSet; +import com.google.common.io.ByteStreams; +import com.google.common.io.Closer; +import com.google.devtools.build.android.Converters.ExistingPathConverter; +import com.google.devtools.build.android.Converters.PathConverter; +import com.google.devtools.build.android.desugar.io.CoreLibraryRewriter; +import com.google.devtools.build.android.desugar.io.HeaderClassLoader; +import com.google.devtools.build.android.desugar.io.IndexedInputs; +import com.google.devtools.build.android.desugar.io.InputFileProvider; +import com.google.devtools.build.android.desugar.io.ThrowingClassLoader; +import com.google.devtools.common.options.Option; +import com.google.devtools.common.options.OptionDocumentationCategory; +import com.google.devtools.common.options.OptionEffectTag; +import com.google.devtools.common.options.OptionsBase; +import com.google.devtools.common.options.OptionsParser; +import com.google.devtools.common.options.ShellQuotedParamsFilePreProcessor; +import java.io.IOError; +import java.io.IOException; +import java.io.InputStream; +import java.io.PrintStream; +import java.lang.reflect.Method; +import java.nio.file.FileSystems; +import java.nio.file.Files; +import java.nio.file.Path; +import java.util.List; +import java.util.Map; +import java.util.stream.Collectors; +import java.util.zip.ZipEntry; +import java.util.zip.ZipFile; +import org.objectweb.asm.ClassReader; +import org.objectweb.asm.Type; + +class KeepScanner { + + public static class KeepScannerOptions extends OptionsBase { + @Option( + name = "input", + defaultValue = "null", + documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, + effectTags = OptionEffectTag.UNKNOWN, + converter = ExistingPathConverter.class, + abbrev = 'i', + help = "Input Jar with classes to scan." + ) + public Path inputJars; + + @Option( + name = "classpath_entry", + allowMultiple = true, + defaultValue = "", + documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, + effectTags = {OptionEffectTag.UNKNOWN}, + converter = ExistingPathConverter.class, + help = + "Ordered classpath (Jar or directory) to resolve symbols in the --input Jar, like " + + "javac's -cp flag." + ) + public List<Path> classpath; + + @Option( + name = "bootclasspath_entry", + allowMultiple = true, + defaultValue = "", + documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, + effectTags = {OptionEffectTag.UNKNOWN}, + converter = ExistingPathConverter.class, + help = + "Bootclasspath that was used to compile the --input Jar with, like javac's " + + "-bootclasspath flag (required)." + ) + public List<Path> bootclasspath; + + @Option( + name = "keep_file", + defaultValue = "null", + documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, + effectTags = OptionEffectTag.UNKNOWN, + converter = PathConverter.class, + help = "Where to write keep rules to." + ) + public Path keepDest; + + @Option( + name = "prefix", + defaultValue = "j$/", + documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, + effectTags = OptionEffectTag.UNKNOWN, + help = "type to scan for." + ) + public String prefix; + } + + public static void main(String... args) throws Exception { + OptionsParser parser = OptionsParser.newOptionsParser(KeepScannerOptions.class); + parser.setAllowResidue(false); + parser.enableParamsFileSupport(new ShellQuotedParamsFilePreProcessor(FileSystems.getDefault())); + parser.parseAndExitUponError(args); + KeepScannerOptions options = parser.getOptions(KeepScannerOptions.class); + + Map<String, ImmutableSet<KeepReference>> seeds; + try (Closer closer = Closer.create()) { + // TODO(kmb): Try to share more of this code with Desugar binary + IndexedInputs classpath = + new IndexedInputs(toRegisteredInputFileProvider(closer, options.classpath)); + IndexedInputs bootclasspath = + new IndexedInputs(toRegisteredInputFileProvider(closer, options.bootclasspath)); + + // Construct classloader from classpath. Since we're assuming the prefix we're looking for + // isn't part of the input itself we shouldn't need to include the input in the classloader. + CoreLibraryRewriter noopRewriter = new CoreLibraryRewriter(""); + ClassLoader classloader = + new HeaderClassLoader(classpath, noopRewriter, + new HeaderClassLoader(bootclasspath, noopRewriter, + new ThrowingClassLoader())); + seeds = scan(checkNotNull(options.inputJars), options.prefix, classloader); + } + + try (PrintStream out = + new PrintStream( + Files.newOutputStream(options.keepDest, CREATE), /*autoFlush=*/ false, "UTF-8")) { + writeKeepDirectives(out, seeds); + } + } + + /** + * Writes a -keep rule for each class listing any members to keep. We sort classes and members + * so the output is deterministic. + */ + private static void writeKeepDirectives( + PrintStream out, Map<String, ImmutableSet<KeepReference>> seeds) { + seeds + .entrySet() + .stream() + .sorted(comparing(Map.Entry::getKey)) + .forEachOrdered( + type -> { + out.printf("-keep class %s {%n", type.getKey().replace('/', '.')); + type.getValue() + .stream() + .filter(KeepReference::isMemberReference) + .sorted(comparing(KeepReference::name).thenComparing(KeepReference::desc)) + .map(ref -> toKeepDescriptor(ref)) + .distinct() // drop duplicates due to method descriptors with different returns + .forEachOrdered(line -> out.append(" ").append(line).append(";").println()); + out.printf("}%n"); + }); + } + + /** Scans for and returns references with owners matching the given prefix grouped by owner. */ + private static Map<String, ImmutableSet<KeepReference>> scan( + Path jarFile, String prefix, ClassLoader classpath) throws IOException { + // We read the Jar sequentially since ZipFile uses locks anyway but then allow scanning each + // class in parallel. + try (ZipFile zip = new ZipFile(jarFile.toFile())) { + return zip.stream() + .filter(entry -> entry.getName().endsWith(".class")) + .map(entry -> readFully(zip, entry)) + .parallel() + .flatMap( + content -> PrefixReferenceScanner.scan(new ClassReader(content), prefix).stream()) + .distinct() // so we don't process the same reference multiple times next + .map(ref -> nearestDeclaration(ref, classpath)) + .collect( + Collectors.groupingByConcurrent( + KeepReference::internalName, ImmutableSet.toImmutableSet())); + } + } + + private static byte[] readFully(ZipFile zip, ZipEntry entry) { + byte[] result = new byte[(int) entry.getSize()]; + try (InputStream content = zip.getInputStream(entry)) { + ByteStreams.readFully(content, result); + return result; + } catch (IOException e) { + throw new IOError(e); + } + } + + /** + * Find the nearest definition of the given reference in the class hierarchy and return the + * modified reference. This is needed b/c bytecode sometimes refers to a method or field using + * an owner type that inherits the method or field instead of defining the member itself. + * In that case we need to find and keep the inherited definition. + */ + private static KeepReference nearestDeclaration(KeepReference ref, ClassLoader classpath) { + if (!ref.isMemberReference() || "<init>".equals(ref.name())) { + return ref; // class and constructor references don't need any further work + } + + Class<?> clazz; + try { + clazz = classpath.loadClass(ref.internalName().replace('/', '.')); + } catch (ClassNotFoundException e) { + throw (NoClassDefFoundError) new NoClassDefFoundError("Couldn't load " + ref).initCause(e); + } + + Class<?> owner = findDeclaringClass(clazz, ref); + if (owner == clazz) { + return ref; + } + String parent = checkNotNull(owner, "Can't resolve: %s", ref).getName().replace('.', '/'); + return KeepReference.memberReference(parent, ref.name(), ref.desc()); + } + + private static Class<?> findDeclaringClass(Class<?> clazz, KeepReference ref) { + if (ref.isFieldReference()) { + try { + return clazz.getField(ref.name()).getDeclaringClass(); + } catch (NoSuchFieldException e) { + // field must be non-public, so search class hierarchy + do { + try { + return clazz.getDeclaredField(ref.name()).getDeclaringClass(); + } catch (NoSuchFieldException ignored) { + // fall through for clarity + } + clazz = clazz.getSuperclass(); + } while (clazz != null); + } + } else { + checkState(ref.isMethodReference()); + Type descriptor = Type.getMethodType(ref.desc()); + for (Method m : clazz.getMethods()) { + if (m.getName().equals(ref.name()) && Type.getType(m).equals(descriptor)) { + return m.getDeclaringClass(); + } + } + do { + // Method must be non-public, so search class hierarchy + for (Method m : clazz.getDeclaredMethods()) { + if (m.getName().equals(ref.name()) && Type.getType(m).equals(descriptor)) { + return m.getDeclaringClass(); + } + } + clazz = clazz.getSuperclass(); + } while (clazz != null); + } + return null; + } + + private static CharSequence toKeepDescriptor(KeepReference member) { + StringBuilder result = new StringBuilder(); + if (member.isMethodReference()) { + if (!"<init>".equals(member.name())) { + result.append("*** "); + } + result.append(member.name()).append("("); + // Ignore return type as it's unique in the source language + boolean first = true; + for (Type param : Type.getMethodType(member.desc()).getArgumentTypes()) { + if (first) { + first = false; + } else { + result.append(", "); + } + result.append(param.getClassName()); + } + result.append(")"); + } else { + checkArgument(member.isFieldReference()); + result.append("*** ").append(member.name()); // field names are unique so ignore descriptor + } + return result; + } + + /** + * Transform a list of Path to a list of InputFileProvider and register them with the given + * closer. + */ + @SuppressWarnings("MustBeClosedChecker") + private static ImmutableList<InputFileProvider> toRegisteredInputFileProvider( + Closer closer, List<Path> paths) throws IOException { + ImmutableList.Builder<InputFileProvider> builder = new ImmutableList.Builder<>(); + for (Path path : paths) { + builder.add(closer.register(InputFileProvider.open(path))); + } + return builder.build(); + } + + private KeepScanner() {} +} |