Add a snapshot of flutter/engine/src/build to our sdk

build/android/rezip/RezipApk.java

Index: build/android/rezip/RezipApk.java
diff --git a/build/android/rezip/RezipApk.java b/build/android/rezip/RezipApk.java
new file mode 100644
index 0000000000000000000000000000000000000000..43d75447c8f5f27011d96a32f0bf359a58f495d5
--- /dev/null
+++ b/build/android/rezip/RezipApk.java
@@ -0,0 +1,448 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
+import java.util.regex.Pattern;
+import java.util.zip.CRC32;
+
+/**
+ * Command line tool used to build APKs which support loading the native code library
+ * directly from the APK file. To construct the APK we rename the native library by
+ * adding the prefix "crazy." to the filename. This is done to prevent the Android
+ * Package Manager from extracting the library. The native code must be page aligned
+ * and uncompressed. The page alignment is implemented by adding a zero filled file
+ * in front of the the native code library. This tool is designed so that running
+ * SignApk and/or zipalign on the resulting APK does not break the page alignment.
+ * This is achieved by outputing the filenames in the same canonical order used
+ * by SignApk and adding the same alignment fields added by zipalign.
+ */
+class RezipApk {
+    // Alignment to use for non-compressed files (must match zipalign).
+    private static final int ALIGNMENT = 4;
+
+    // Alignment to use for non-compressed *.so files
+    private static final int LIBRARY_ALIGNMENT = 4096;
+
+    // Files matching this pattern are not copied to the output when adding alignment.
+    // When reordering and verifying the APK they are copied to the end of the file.
+    private static Pattern sMetaFilePattern =
+            Pattern.compile("^(META-INF/((.*)[.](SF|RSA|DSA)|com/android/otacert))|("
+                    + Pattern.quote(JarFile.MANIFEST_NAME) + ")$");
+
+    // Pattern for matching a shared library in the APK
+    private static Pattern sLibraryPattern = Pattern.compile("^lib/[^/]*/lib.*[.]so$");
+    // Pattern for match the crazy linker in the APK
+    private static Pattern sCrazyLinkerPattern =
+            Pattern.compile("^lib/[^/]*/libchromium_android_linker.so$");
+    // Pattern for matching a crazy loaded shared library in the APK
+    private static Pattern sCrazyLibraryPattern = Pattern.compile("^lib/[^/]*/crazy.lib.*[.]so$");
+
+    private static boolean isLibraryFilename(String filename) {
+        return sLibraryPattern.matcher(filename).matches()
+                && !sCrazyLinkerPattern.matcher(filename).matches();
+    }
+
+    private static boolean isCrazyLibraryFilename(String filename) {
+        return sCrazyLibraryPattern.matcher(filename).matches();
+    }
+
+    private static String renameLibraryForCrazyLinker(String filename) {
+        int lastSlash = filename.lastIndexOf('/');
+        // We rename the library, so that the Android Package Manager
+        // no longer extracts the library.
+        return filename.substring(0, lastSlash + 1) + "crazy." + filename.substring(lastSlash + 1);
+    }
+
+    /**
+     * Wraps another output stream, counting the number of bytes written.
+     */
+    private static class CountingOutputStream extends OutputStream {
+        private long mCount = 0;
+        private OutputStream mOut;
+
+        public CountingOutputStream(OutputStream out) {
+            this.mOut = out;
+        }
+
+        /** Returns the number of bytes written. */
+        public long getCount() {
+            return mCount;
+        }
+
+        @Override public void write(byte[] b, int off, int len) throws IOException {
+            mOut.write(b, off, len);
+            mCount += len;
+        }
+
+        @Override public void write(int b) throws IOException {
+            mOut.write(b);
+            mCount++;
+        }
+
+        @Override public void close() throws IOException {
+            mOut.close();
+        }
+
+        @Override public void flush() throws IOException {
+            mOut.flush();
+        }
+    }
+
+    private static String outputName(JarEntry entry, boolean rename) {
+        String inName = entry.getName();
+        if (rename && entry.getSize() > 0 && isLibraryFilename(inName)) {
+            return renameLibraryForCrazyLinker(inName);
+        }
+        return inName;
+    }
+
+    /**
+     * Comparator used to sort jar entries from the input file.
+     * Sorting is done based on the output filename (which maybe renamed).
+     * Filenames are in natural string order, except that filenames matching
+     * the meta-file pattern are always after other files. This is so the manifest
+     * and signature are at the end of the file after any alignment file.
+     */
+    private static class EntryComparator implements Comparator<JarEntry> {
+        private boolean mRename;
+
+        public EntryComparator(boolean rename) {
+            mRename = rename;
+        }
+
+        @Override
+        public int compare(JarEntry j1, JarEntry j2) {
+            String o1 = outputName(j1, mRename);
+            String o2 = outputName(j2, mRename);
+            boolean o1Matches = sMetaFilePattern.matcher(o1).matches();
+            boolean o2Matches = sMetaFilePattern.matcher(o2).matches();
+            if (o1Matches != o2Matches) {
+                return o1Matches ? 1 : -1;
+            } else {
+                return o1.compareTo(o2);
+            }
+        }
+    }
+
+    // Build an ordered list of jar entries. The jar entries from the input are
+    // sorted based on the output filenames (which maybe renamed). If |omitMetaFiles|
+    // is true do not include the jar entries for the META-INF files.
+    // Entries are ordered in the deterministic order used by SignApk.
+    private static List<JarEntry> getOutputFileOrderEntries(
+            JarFile jar, boolean omitMetaFiles, boolean rename) {
+        List<JarEntry> entries = new ArrayList<JarEntry>();
+        for (Enumeration<JarEntry> e = jar.entries(); e.hasMoreElements(); ) {
+            JarEntry entry = e.nextElement();
+            if (entry.isDirectory()) {
+                continue;
+            }
+            if (omitMetaFiles && sMetaFilePattern.matcher(entry.getName()).matches()) {
+                continue;
+            }
+            entries.add(entry);
+        }
+
+        // We sort the input entries by name. When present META-INF files
+        // are sorted to the end.
+        Collections.sort(entries, new EntryComparator(rename));
+        return entries;
+    }
+
+    /**
+     * Add a zero filled alignment file at this point in the zip file,
+     * The added file will be added before |name| and after |prevName|.
+     * The size of the alignment file is such that the location of the
+     * file |name| will be on a LIBRARY_ALIGNMENT boundary.
+     *
+     * Note this arrangement is devised so that running SignApk and/or zipalign on the resulting
+     * file will not alter the alignment.
+     *
+     * @param offset number of bytes into the output file at this point.
+     * @param timestamp time in millis since the epoch to include in the header.
+     * @param name the name of the library filename.
+     * @param prevName the name of the previous file in the archive (or null).
+     * @param out jar output stream to write the alignment file to.
+     *
+     * @throws IOException if the output file can not be written.
+     */
+    private static void addAlignmentFile(
+            long offset, long timestamp, String name, String prevName,
+            JarOutputStream out) throws IOException {
+
+        // Compute the start and alignment of the library, as if it was next.
+        int headerSize = JarFile.LOCHDR + name.length();
+        long libOffset = offset + headerSize;
+        int libNeeded = LIBRARY_ALIGNMENT - (int) (libOffset % LIBRARY_ALIGNMENT);
+        if (libNeeded == LIBRARY_ALIGNMENT) {
+            // Already aligned, no need to added alignment file.
+            return;
+        }
+
+        // Check that there is not another file between the library and the
+        // alignment file.
+        String alignName = name.substring(0, name.length() - 2) + "align";
+        if (prevName != null && prevName.compareTo(alignName) >= 0) {
+            throw new UnsupportedOperationException(
+                "Unable to insert alignment file, because there is "
+                + "another file in front of the file to be aligned. "
+                + "Other file: " + prevName + " Alignment file: " + alignName
+                + " file: " + name);
+        }
+
+        // Compute the size of the alignment file header.
+        headerSize = JarFile.LOCHDR + alignName.length();
+        // We are going to add an alignment file of type STORED. This file
+        // will itself induce a zipalign alignment adjustment.
+        int extraNeeded =
+                (ALIGNMENT - (int) ((offset + headerSize) % ALIGNMENT)) % ALIGNMENT;
+        headerSize += extraNeeded;
+
+        if (libNeeded < headerSize + 1) {
+            // The header was bigger than the alignment that we need, add another page.
+            libNeeded += LIBRARY_ALIGNMENT;
+        }
+        // Compute the size of the alignment file.
+        libNeeded -= headerSize;
+
+        // Build the header for the alignment file.
+        byte[] zeroBuffer = new byte[libNeeded];
+        JarEntry alignEntry = new JarEntry(alignName);
+        alignEntry.setMethod(JarEntry.STORED);
+        alignEntry.setSize(libNeeded);
+        alignEntry.setTime(timestamp);
+        CRC32 crc = new CRC32();
+        crc.update(zeroBuffer);
+        alignEntry.setCrc(crc.getValue());
+
+        if (extraNeeded != 0) {
+            alignEntry.setExtra(new byte[extraNeeded]);
+        }
+
+        // Output the alignment file.
+        out.putNextEntry(alignEntry);
+        out.write(zeroBuffer);
+        out.closeEntry();
+        out.flush();
+    }
+
+    // Make a JarEntry for the output file which corresponds to the input
+    // file. The output file will be called |name|. The output file will always
+    // be uncompressed (STORED). If the input is not STORED it is necessary to inflate
+    // it to compute the CRC and size of the output entry.
+    private static JarEntry makeStoredEntry(String name, JarEntry inEntry, JarFile in)
+            throws IOException {
+        JarEntry outEntry = new JarEntry(name);
+        outEntry.setMethod(JarEntry.STORED);
+
+        if (inEntry.getMethod() == JarEntry.STORED) {
+            outEntry.setCrc(inEntry.getCrc());
+            outEntry.setSize(inEntry.getSize());
+        } else {
+            // We are inflating the file. We need to compute the CRC and size.
+            byte[] buffer = new byte[4096];
+            CRC32 crc = new CRC32();
+            int size = 0;
+            int num;
+            InputStream data = in.getInputStream(inEntry);
+            while ((num = data.read(buffer)) > 0) {
+                crc.update(buffer, 0, num);
+                size += num;
+            }
+            data.close();
+            outEntry.setCrc(crc.getValue());
+            outEntry.setSize(size);
+        }
+        return outEntry;
+    }
+
+    /**
+     * Copy the contents of the input APK file to the output APK file. If |rename| is
+     * true then non-empty libraries (*.so) in the input will be renamed by prefixing
+     * "crazy.". This is done to prevent the Android Package Manager extracting the
+     * library. Note the crazy linker itself is not renamed, for bootstrapping reasons.
+     * Empty libraries are not renamed (they are in the APK to workaround a bug where
+     * the Android Package Manager fails to delete old versions when upgrading).
+     * There must be exactly one "crazy" library in the output stream. The "crazy"
+     * library will be uncompressed and page aligned in the output stream. Page
+     * alignment is implemented by adding a zero filled file, regular alignment is
+     * implemented by adding a zero filled extra field to the zip file header. If
+     * |addAlignment| is true a page alignment file is added, otherwise the "crazy"
+     * library must already be page aligned. Care is taken so that the output is generated
+     * in the same way as SignApk. This is important so that running SignApk and
+     * zipalign on the output does not break the page alignment. The archive may not
+     * contain a "*.apk" as SignApk has special nested signing logic that we do not
+     * support.
+     *
+     * @param in The input APK File.
+     * @param out The output APK stream.
+     * @param countOut Counting output stream (to measure the current offset).
+     * @param addAlignment Whether to add the alignment file or just check.
+     * @param rename Whether to rename libraries to be "crazy".
+     *
+     * @throws IOException if the output file can not be written.
+     */
+    private static void rezip(
+            JarFile in, JarOutputStream out, CountingOutputStream countOut,
+            boolean addAlignment, boolean rename) throws IOException {
+
+        List<JarEntry> entries = getOutputFileOrderEntries(in, addAlignment, rename);
+        long timestamp = System.currentTimeMillis();
+        byte[] buffer = new byte[4096];
+        boolean firstEntry = true;
+        String prevName = null;
+        int numCrazy = 0;
+        for (JarEntry inEntry : entries) {
+            // Rename files, if specied.
+            String name = outputName(inEntry, rename);
+            if (name.endsWith(".apk")) {
+                throw new UnsupportedOperationException(
+                        "Nested APKs are not supported: " + name);
+            }
+
+            // Build the header.
+            JarEntry outEntry = null;
+            boolean isCrazy = isCrazyLibraryFilename(name);
+            if (isCrazy) {
+                // "crazy" libraries are alway output uncompressed (STORED).
+                outEntry = makeStoredEntry(name, inEntry, in);
+                numCrazy++;
+                if (numCrazy > 1) {
+                    throw new UnsupportedOperationException(
+                            "Found more than one library\n"
+                            + "Multiple libraries are not supported for APKs that use "
+                            + "'load_library_from_zip'.\n"
+                            + "See crbug/388223.\n"
+                            + "Note, check that your build is clean.\n"
+                            + "An unclean build can incorrectly incorporate old "
+                            + "libraries in the APK.");
+                }
+            } else if (inEntry.getMethod() == JarEntry.STORED) {
+                // Preserve the STORED method of the input entry.
+                outEntry = new JarEntry(inEntry);
+                outEntry.setExtra(null);
+            } else {
+                // Create a new entry so that the compressed len is recomputed.
+                outEntry = new JarEntry(name);
+            }
+            outEntry.setTime(timestamp);
+
+            // Compute and add alignment
+            long offset = countOut.getCount();
+            if (firstEntry) {
+                // The first entry in a jar file has an extra field of
+                // four bytes that you can't get rid of; any extra
+                // data you specify in the JarEntry is appended to
+                // these forced four bytes.  This is JAR_MAGIC in
+                // JarOutputStream; the bytes are 0xfeca0000.
+                firstEntry = false;
+                offset += 4;
+            }
+            if (outEntry.getMethod() == JarEntry.STORED) {
+                if (isCrazy) {
+                    if (addAlignment) {
+                        addAlignmentFile(offset, timestamp, name, prevName, out);
+                    }
+                    // We check that we did indeed get to a page boundary.
+                    offset = countOut.getCount() + JarFile.LOCHDR + name.length();
+                    if ((offset % LIBRARY_ALIGNMENT) != 0) {
+                        throw new AssertionError(
+                                "Library was not page aligned when verifying page alignment. "
+                                + "Library name: " + name + " Expected alignment: "
+                                + LIBRARY_ALIGNMENT + "Offset: " + offset + " Error: "
+                                + (offset % LIBRARY_ALIGNMENT));
+                    }
+                } else {
+                    // This is equivalent to zipalign.
+                    offset += JarFile.LOCHDR + name.length();
+                    int needed = (ALIGNMENT - (int) (offset % ALIGNMENT)) % ALIGNMENT;
+                    if (needed != 0) {
+                        outEntry.setExtra(new byte[needed]);
+                    }
+                }
+            }
+            out.putNextEntry(outEntry);
+
+            // Copy the data from the input to the output
+            int num;
+            InputStream data = in.getInputStream(inEntry);
+            while ((num = data.read(buffer)) > 0) {
+                out.write(buffer, 0, num);
+            }
+            data.close();
+            out.closeEntry();
+            out.flush();
+            prevName = name;
+        }
+        if (numCrazy == 0) {
+            throw new AssertionError("There was no crazy library in the archive");
+        }
+    }
+
+    private static void usage() {
+        System.err.println("Usage: prealignapk (addalignment|reorder) input.apk output.apk");
+        System.err.println("\"crazy\" libraries are always inflated in the output");
+        System.err.println(
+                "  renamealign  - rename libraries with \"crazy.\" prefix and add alignment file");
+        System.err.println("  align        - add alignment file");
+        System.err.println("  reorder      - re-creates canonical ordering and checks alignment");
+        System.exit(2);
+    }
+
+    public static void main(String[] args) throws IOException {
+        if (args.length != 3) usage();
+
+        boolean addAlignment = false;
+        boolean rename = false;
+        if (args[0].equals("renamealign")) {
+            // Normal case. Before signing we rename the library and add an alignment file.
+            addAlignment = true;
+            rename = true;
+        } else if (args[0].equals("align")) {
+            // LGPL compliance case. Before signing, we add an alignment file to a
+            // reconstructed APK which already contains the "crazy" library.
+            addAlignment = true;
+            rename = false;
+        } else if (args[0].equals("reorder")) {
+            // Normal case. After jarsigning we write the file in the canonical order and check.
+            addAlignment = false;
+        } else {
+            usage();
+        }
+
+        String inputFilename = args[1];
+        String outputFilename = args[2];
+
+        JarFile inputJar = null;
+        FileOutputStream outputFile = null;
+
+        try {
+            inputJar = new JarFile(new File(inputFilename), true);
+            outputFile = new FileOutputStream(outputFilename);
+
+            CountingOutputStream outCount = new CountingOutputStream(outputFile);
+            JarOutputStream outputJar = new JarOutputStream(outCount);
+
+            // Match the compression level used by SignApk.
+            outputJar.setLevel(9);
+
+            rezip(inputJar, outputJar, outCount, addAlignment, rename);
+            outputJar.close();
+        } finally {
+            if (inputJar != null) inputJar.close();
+            if (outputFile != null) outputFile.close();
+        }
+    }
+}