Merge "ApkSignerEngine abstraction for apksigner-core library."
diff --git a/tools/apksigner/core/src/com/android/apksigner/core/ApkSignerEngine.java b/tools/apksigner/core/src/com/android/apksigner/core/ApkSignerEngine.java
new file mode 100644
index 0000000..36f2a08
--- /dev/null
+++ b/tools/apksigner/core/src/com/android/apksigner/core/ApkSignerEngine.java
@@ -0,0 +1,407 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.android.apksigner.core;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.security.InvalidKeyException;
+import java.security.SignatureException;
+import java.util.List;
+
+import com.android.apksigner.core.util.DataSink;
+import com.android.apksigner.core.util.DataSource;
+
+/**
+ * APK signing logic which is independent of how input and output APKs are stored, parsed, and
+ * generated.
+ *
+ * <p><h3>Operating Model</h3>
+ *
+ * The abstract operating model is that there is an input APK which is being signed, thus producing
+ * an output APK. In reality, there may be just an output APK being built from scratch, or the input APK and
+ * the output APK may be the same file. Because this engine does not deal with reading and writing
+ * files, it can handle all of these scenarios.
+ *
+ * <p>The engine is stateful and thus cannot be used for signing multiple APKs. However, once
+ * the engine signed an APK, the engine can be used to re-sign the APK after it has been modified.
+ * This may be more efficient than signing the APK using a new instance of the engine. See
+ * <a href="#incremental">Incremental Operation</a>.
+ *
+ * <p>In the engine's operating model, a signed APK is produced as follows.
+ * <ol>
+ * <li>JAR entries to be signed are output,</li>
+ * <li>JAR archive is signed using JAR signing, thus adding the so-called v1 signature to the
+ * output,</li>
+ * <li>JAR archive is signed using APK Signature Scheme v2, thus adding the so-called v2 signature
+ * to the output.</li>
+ * </ol>
+ *
+ * <p>The input APK may contain JAR entries which, depending on the engine's configuration, may or
+ * may not be output (e.g., existing signatures may need to be preserved or stripped) or which the
+ * engine will overwrite as part of signing. The engine thus offers {@link #inputJarEntry(String)}
+ * which tells the client whether the input JAR entry needs to be output. This avoids the need for
+ * the client to hard-code the aspects of APK signing which determine which parts of input must be
+ * ignored. Similarly, the engine offers {@link #inputApkSigningBlock(DataSource)} to help the
+ * client avoid dealing with preserving or stripping APK Signature Scheme v2 signature of the input
+ * APK.
+ *
+ * <p>To use the engine to sign an input APK (or a collection of JAR entries), follow these
+ * steps:
+ * <ol>
+ * <li>Obtain a new instance of the engine -- engine instances are stateful and thus cannot be used
+ * for signing multiple APKs.</li>
+ * <li>Locate the input APK's APK Signing Block and provide it to
+ * {@link #inputApkSigningBlock(DataSource)}.</li>
+ * <li>For each JAR entry in the input APK, invoke {@link #inputJarEntry(String)} to determine
+ * whether this entry should be output. The engine may request to inspect the entry.</li>
+ * <li>For each output JAR entry, invoke {@link #outputJarEntry(String)} which may request to
+ * inspect the entry.</li>
+ * <li>Once all JAR entries have been output, invoke {@link #outputJarEntries()} which may request
+ * that additional JAR entries are output. These entries comprise the output APK's JAR
+ * signature.</li>
+ * <li>Locate the ZIP Central Directory and ZIP End of Central Directory sections in the output and
+ * invoke {@link #outputZipSections(DataSource, DataSource, DataSource)} which may request that
+ * an APK Signature Block is inserted before the ZIP Central Directory. The block contains the
+ * output APK's APK Signature Scheme v2 signature.</li>
+ * <li>Invoke {@link #outputDone()} to signal that the APK was output in full. The engine will
+ * confirm that the output APK is signed.</li>
+ * <li>Invoke {@link #close()} to signal that the engine will no longer be used. This lets the
+ * engine free any resources it no longer needs.
+ * </ol>
+ *
+ * <p>Some invocations of the engine may provide the client with a task to perform. The client is
+ * expected to perform all requested tasks before proceeding to the next stage of signing. See
+ * documentation of each method about the deadlines for performing the tasks requested by the
+ * method.
+ *
+ * <p><h3 id="incremental">Incremental Operation</h3></a>
+ *
+ * The engine supports incremental operation where a signed APK is produced, then modified and
+ * re-signed. This may be useful for IDEs, where an app is frequently re-signed after small changes
+ * by the developer. Re-signing may be more efficient than signing from scratch.
+ *
+ * <p>To use the engine in incremental mode, keep notifying the engine of changes to the APK through
+ * {@link #inputApkSigningBlock(DataSource)}, {@link #inputJarEntry(String)},
+ * {@link #inputJarEntryRemoved(String)}, {@link #outputJarEntry(String)},
+ * and {@link #outputJarEntryRemoved(String)}, perform the tasks requested by the engine through
+ * these methods, and, when a new signed APK is desired, run through steps 5 onwards to re-sign the
+ * APK.
+ *
+ * <p><h3>Output-only Operation</h3>
+ *
+ * The engine's abstract operating model consists of an input APK and an output APK. However, it is
+ * possible to use the engine in output-only mode where the engine's {@code input...} methods are
+ * not invoked. In this mode, the engine has less control over output because it cannot request that
+ * some JAR entries are not output. Nevertheless, the engine will attempt to make the output APK
+ * signed and will report an error if cannot do so.
+ */
+public interface ApkSignerEngine extends Closeable {
+
+ /**
+ * Indicates to this engine that the input APK contains the provided APK Signing Block. The
+ * block may contain signatures of the input APK, such as APK Signature Scheme v2 signatures.
+ *
+ * @param apkSigningBlock APK signing block of the input APK. The provided data source is
+ * guaranteed to not be used by the engine after this method terminates.
+ *
+ * @throws IllegalStateException if this engine is closed
+ */
+ void inputApkSigningBlock(DataSource apkSigningBlock) throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that the specified JAR entry was encountered in the input APK.
+ *
+ * <p>When an input entry is updated/changed, it's OK to not invoke
+ * {@link #inputJarEntryRemoved(String)} before invoking this method.
+ *
+ * @return instructions about how to proceed with this entry
+ *
+ * @throws IllegalStateException if this engine is closed
+ */
+ InputJarEntryInstructions inputJarEntry(String entryName) throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that the specified JAR entry was output.
+ *
+ * <p>It is unnecessary to invoke this method for entries added to output by this engine (e.g.,
+ * requested by {@link #outputJarEntries()}) provided the entries were output with exactly the
+ * data requested by the engine.
+ *
+ * <p>When an already output entry is updated/changed, it's OK to not invoke
+ * {@link #outputJarEntryRemoved(String)} before invoking this method.
+ *
+ * @return request to inspect the entry or {@code null} if the engine does not need to inspect
+ * the entry. The request must be fulfilled before {@link #outputJarEntries()} is
+ * invoked.
+ *
+ * @throws IllegalStateException if this engine is closed
+ */
+ InspectJarEntryRequest outputJarEntry(String entryName) throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that the specified JAR entry was removed from the input. It's safe
+ * to invoke this for entries for which {@link #inputJarEntry(String)} hasn't been invoked.
+ *
+ * @return output policy of this JAR entry. The policy indicates how this input entry affects
+ * the output APK. The client of this engine should use this information to determine
+ * how the removal of this input APK's JAR entry affects the output APK.
+ *
+ * @throws IllegalStateException if this engine is closed
+ */
+ InputJarEntryInstructions.OutputPolicy inputJarEntryRemoved(String entryName)
+ throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that the specified JAR entry was removed from the output. It's safe
+ * to invoke this for entries for which {@link #outputJarEntry(String)} hasn't been invoked.
+ *
+ * @throws IllegalStateException if this engine is closed
+ */
+ void outputJarEntryRemoved(String entryName) throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that all JAR entries have been output.
+ *
+ *
+ * @return request to add JAR signature to the output or {@code null} if there is no need to add
+ * a JAR signature. The request will contain additional JAR entries to be output. The
+ * request must be fulfilled before
+ * {@link #outputZipSections(DataSource, DataSource, DataSource)} is invoked.
+ *
+ * @throws InvalidKeyException if a signature could not be generated because a signing key is
+ * not suitable for generating the signature
+ * @throws SignatureException if an error occurred while generating the JAR signature
+ * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR
+ * entries, or if the engine is closed
+ */
+ OutputJarSignatureRequest outputJarEntries() throws InvalidKeyException, SignatureException;
+
+ /**
+ * Indicates to this engine that the ZIP sections comprising the output APK have been output.
+ *
+ * <p>The provided data sources are guaranteed to not be used by the engine after this method
+ * terminates.
+ *
+ * @param zipEntries the section of ZIP archive containing Local File Header records and data of
+ * the ZIP entries. In a well-formed archive, this section starts at the start of the
+ * archive and extends all the way to the ZIP Central Directory.
+ * @param zipCentralDirectory ZIP Central Directory section
+ * @param zipEocd ZIP End of Central Directory (EoCD) record
+ *
+ * @return request to add an APK Signing Block to the output or {@code null} if the output must
+ * not contain an APK Signing Block. The request must be fulfilled before
+ * {@link #outputDone()} is invoked.
+ *
+ * @throws IOException if an I/O error occurs while reading the provided ZIP sections
+ * @throws InvalidKeyException if a signature could not be generated because a signing key is
+ * not suitable for generating the signature
+ * @throws SignatureException if an error occurred while generating the APK's signature
+ * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR
+ * entries or to output JAR signature, or if the engine is closed
+ */
+ OutputApkSigningBlockRequest outputZipSections(
+ DataSource zipEntries,
+ DataSource zipCentralDirectory,
+ DataSource zipEocd) throws IOException, InvalidKeyException, SignatureException;
+
+ /**
+ * Indicates to this engine that the signed APK was output.
+ *
+ * <p>This does not change the output APK. The method helps the client confirm that the current
+ * output is signed.
+ *
+ * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR
+ * entries or to output signatures, or if the engine is closed
+ */
+ void outputDone() throws IllegalStateException;
+
+ /**
+ * Indicates to this engine that it will no longer be used. Invoking this on an already closed
+ * engine is OK.
+ *
+ * <p>This does not change the output APK. For example, if the output APK is not yet fully
+ * signed, it will remain so after this method terminates.
+ */
+ @Override
+ void close();
+
+ /**
+ * Instructions about how to handle an input APK's JAR entry.
+ *
+ * <p>The instructions indicate whether to output the entry (see {@link #getOutputPolicy()}) and
+ * may contain a request to inspect the entry (see {@link #getInspectJarEntryRequest()}), in
+ * which case the request must be fulfilled before {@link ApkSignerEngine#outputJarEntries()} is
+ * invoked.
+ */
+ public static class InputJarEntryInstructions {
+ private final OutputPolicy mOutputPolicy;
+ private final InspectJarEntryRequest mInspectJarEntryRequest;
+
+ /**
+ * Constructs a new {@code InputJarEntryInstructions} instance with the provided entry
+ * output policy and without a request to inspect the entry.
+ */
+ public InputJarEntryInstructions(OutputPolicy outputPolicy) {
+ this(outputPolicy, null);
+ }
+
+ /**
+ * Constructs a new {@code InputJarEntryInstructions} instance with the provided entry
+ * output mode and with the provided request to inspect the entry.
+ *
+ * @param inspectJarEntryRequest request to inspect the entry or {@code null} if there's no
+ * need to inspect the entry.
+ */
+ public InputJarEntryInstructions(
+ OutputPolicy outputPolicy,
+ InspectJarEntryRequest inspectJarEntryRequest) {
+ mOutputPolicy = outputPolicy;
+ mInspectJarEntryRequest = inspectJarEntryRequest;
+ }
+
+ /**
+ * Returns the output policy for this entry.
+ */
+ public OutputPolicy getOutputPolicy() {
+ return mOutputPolicy;
+ }
+
+ /**
+ * Returns the request to inspect the JAR entry or {@code null} if there is no need to
+ * inspect the entry.
+ */
+ public InspectJarEntryRequest getInspectJarEntryRequest() {
+ return mInspectJarEntryRequest;
+ }
+
+ /**
+ * Output policy for an input APK's JAR entry.
+ */
+ public static enum OutputPolicy {
+ /** Entry must not be output. */
+ SKIP,
+
+ /** Entry should be output. */
+ OUTPUT,
+
+ /** Entry will be output by the engine. The client can thus ignore this input entry. */
+ OUTPUT_BY_ENGINE,
+ }
+ }
+
+ /**
+ * Request to inspect the specified JAR entry.
+ *
+ * <p>The entry's uncompressed data must be provided to the data sink returned by
+ * {@link #getDataSink()}. Once the entry's data has been provided to the sink, {@link #done()}
+ * must be invoked.
+ */
+ interface InspectJarEntryRequest {
+
+ /**
+ * Returns the data sink into which the entry's uncompressed data should be sent.
+ */
+ DataSink getDataSink();
+
+ /**
+ * Indicates that entry's data has been provided in full.
+ */
+ void done();
+
+ /**
+ * Returns the name of the JAR entry.
+ */
+ String getEntryName();
+ }
+
+ /**
+ * Request to add JAR signature (aka v1 signature) to the output APK.
+ *
+ * <p>Entries listed in {@link #getAdditionalJarEntries()} must be added to the output APK after
+ * which {@link #done()} must be invoked.
+ */
+ interface OutputJarSignatureRequest {
+
+ /**
+ * Returns JAR entries that must be added to the output APK.
+ */
+ List<JarEntry> getAdditionalJarEntries();
+
+ /**
+ * Indicates that the JAR entries contained in this request were added to the output APK.
+ */
+ void done();
+
+ /**
+ * JAR entry.
+ */
+ public static class JarEntry {
+ private final String mName;
+ private final byte[] mData;
+
+ /**
+ * Constructs a new {@code JarEntry} with the provided name and data.
+ *
+ * @param data uncompressed data of the entry. Changes to this array will not be
+ * reflected in {@link #getData()}.
+ */
+ public JarEntry(String name, byte[] data) {
+ mName = name;
+ mData = data.clone();
+ }
+
+ /**
+ * Returns the name of this ZIP entry.
+ */
+ public String getName() {
+ return mName;
+ }
+
+ /**
+ * Returns the uncompressed data of this JAR entry.
+ */
+ public byte[] getData() {
+ return mData.clone();
+ }
+ }
+ }
+
+ /**
+ * Request to add the specified APK Signing Block to the output APK. APK Signature Scheme v2
+ * signature(s) of the APK are contained in this block.
+ *
+ * <p>The APK Signing Block returned by {@link #getApkSigningBlock()} must be placed into the
+ * output APK such that the block is immediately before the ZIP Central Directory, the offset of
+ * ZIP Central Directory in the ZIP End of Central Directory record must be adjusted
+ * accordingly, and then {@link #done()} must be invoked.
+ *
+ * <p>If the output contains an APK Signing Block, that block must be replaced by the block
+ * contained in this request.
+ */
+ interface OutputApkSigningBlockRequest {
+
+ /**
+ * Returns the APK Signing Block.
+ */
+ byte[] getApkSigningBlock();
+
+ /**
+ * Indicates that the APK Signing Block was output as requested.
+ */
+ void done();
+ }
+}
