/*
 * Copyright (C) 2013 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 android.util.jar;

import android.system.ErrnoException;
import android.system.Os;
import android.system.OsConstants;

import dalvik.system.CloseGuard;
import java.io.FileDescriptor;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.cert.Certificate;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import java.util.jar.JarFile;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
import java.util.zip.ZipEntry;
import libcore.io.IoBridge;
import libcore.io.IoUtils;
import libcore.io.Streams;

A subset of the JarFile API implemented as a thin wrapper over
system/core/libziparchive.
@hide
for internal use only. Not API compatible (or as forgiving) as JarFile/**
 * A subset of the JarFile API implemented as a thin wrapper over
 * system/core/libziparchive.
 *
 * @hide for internal use only. Not API compatible (or as forgiving) as
 *        {@link java.util.jar.JarFile}
 */
public final class StrictJarFile {

    private final long nativeHandle;

    // NOTE: It's possible to share a file descriptor with the native
    // code, at the cost of some additional complexity.
    private final FileDescriptor fd;

    private final StrictJarManifest manifest;
    private final StrictJarVerifier verifier;

    private final boolean isSigned;

    private final CloseGuard guard = CloseGuard.get();
    private boolean closed;

    public StrictJarFile(String fileName)
            throws IOException, SecurityException {
        this(fileName, true, true);
    }

    public StrictJarFile(FileDescriptor fd)
            throws IOException, SecurityException {
        this(fd, true, true);
    }

    public StrictJarFile(FileDescriptor fd,
            boolean verify,
            boolean signatureSchemeRollbackProtectionsEnforced)
                    throws IOException, SecurityException {
        this("[fd:" + fd.getInt$() + "]", fd, verify,
                signatureSchemeRollbackProtectionsEnforced);
    }

    public StrictJarFile(String fileName,
            boolean verify,
            boolean signatureSchemeRollbackProtectionsEnforced)
                    throws IOException, SecurityException {
        this(fileName, IoBridge.open(fileName, OsConstants.O_RDONLY),
                verify, signatureSchemeRollbackProtectionsEnforced);
    }

    
Params:
name – of the archive (not necessarily a path).
fd – seekable file descriptor for the JAR file.
verify – whether to verify the file's JAR signatures and collect the corresponding
       signer certificates.
signatureSchemeRollbackProtectionsEnforced – true to enforce protections against stripping newer signature schemes (e.g., APK Signature Scheme v2) from the file, or false to ignore any such protections. This parameter is ignored when verify is false./**
     * @param name of the archive (not necessarily a path).
     * @param fd seekable file descriptor for the JAR file.
     * @param verify whether to verify the file's JAR signatures and collect the corresponding
     *        signer certificates.
     * @param signatureSchemeRollbackProtectionsEnforced {@code true} to enforce protections against
     *        stripping newer signature schemes (e.g., APK Signature Scheme v2) from the file, or
     *        {@code false} to ignore any such protections. This parameter is ignored when
     *        {@code verify} is {@code false}.
     */
    private StrictJarFile(String name,
            FileDescriptor fd,
            boolean verify,
            boolean signatureSchemeRollbackProtectionsEnforced)
                    throws IOException, SecurityException {
        this.nativeHandle = nativeOpenJarFile(name, fd.getInt$());
        this.fd = fd;

        try {
            // Read the MANIFEST and signature files up front and try to
            // parse them. We never want to accept a JAR File with broken signatures
            // or manifests, so it's best to throw as early as possible.
            if (verify) {
                HashMap<String, byte[]> metaEntries = getMetaEntries();
                this.manifest = new StrictJarManifest(metaEntries.get(JarFile.MANIFEST_NAME), true);
                this.verifier =
                        new StrictJarVerifier(
                                name,
                                manifest,
                                metaEntries,
                                signatureSchemeRollbackProtectionsEnforced);
                Set<String> files = manifest.getEntries().keySet();
                for (String file : files) {
                    if (findEntry(file) == null) {
                        throw new SecurityException("File " + file + " in manifest does not exist");
                    }
                }

                isSigned = verifier.readCertificates() && verifier.isSignedJar();
            } else {
                isSigned = false;
                this.manifest = null;
                this.verifier = null;
            }
        } catch (IOException | SecurityException e) {
            nativeClose(this.nativeHandle);
            IoUtils.closeQuietly(fd);
            closed = true;
            throw e;
        }

        guard.open("close");
    }

    public StrictJarManifest getManifest() {
        return manifest;
    }

    public Iterator<ZipEntry> iterator() throws IOException {
        return new EntryIterator(nativeHandle, "");
    }

    public ZipEntry findEntry(String name) {
        return nativeFindEntry(nativeHandle, name);
    }

    
Return all certificate chains for a given ZipEntry belonging to this jar. This method MUST be called only after fully exhausting the InputStream belonging to this entry. Returns null if this jar file isn't signed or if this method is called before the stream is processed. /**
     * Return all certificate chains for a given {@link ZipEntry} belonging to this jar.
     * This method MUST be called only after fully exhausting the InputStream belonging
     * to this entry.
     *
     * Returns {@code null} if this jar file isn't signed or if this method is
     * called before the stream is processed.
     */
    public Certificate[][] getCertificateChains(ZipEntry ze) {
        if (isSigned) {
            return verifier.getCertificateChains(ze.getName());
        }

        return null;
    }

    
Return all certificates for a given ZipEntry belonging to this jar. This method MUST be called only after fully exhausting the InputStream belonging to this entry. Returns null if this jar file isn't signed or if this method is called before the stream is processed. 
Deprecated:
Switch callers to use getCertificateChains instead/**
     * Return all certificates for a given {@link ZipEntry} belonging to this jar.
     * This method MUST be called only after fully exhausting the InputStream belonging
     * to this entry.
     *
     * Returns {@code null} if this jar file isn't signed or if this method is
     * called before the stream is processed.
     *
     * @deprecated Switch callers to use getCertificateChains instead
     */
    @Deprecated
    public Certificate[] getCertificates(ZipEntry ze) {
        if (isSigned) {
            Certificate[][] certChains = verifier.getCertificateChains(ze.getName());

            // Measure number of certs.
            int count = 0;
            for (Certificate[] chain : certChains) {
                count += chain.length;
            }

            // Create new array and copy all the certs into it.
            Certificate[] certs = new Certificate[count];
            int i = 0;
            for (Certificate[] chain : certChains) {
                System.arraycopy(chain, 0, certs, i, chain.length);
                i += chain.length;
            }

            return certs;
        }

        return null;
    }

    public InputStream getInputStream(ZipEntry ze) {
        final InputStream is = getZipInputStream(ze);

        if (isSigned) {
            StrictJarVerifier.VerifierEntry entry = verifier.initEntry(ze.getName());
            if (entry == null) {
                return is;
            }

            return new JarFileInputStream(is, ze.getSize(), entry);
        }

        return is;
    }

    public void close() throws IOException {
        if (!closed) {
            if (guard != null) {
                guard.close();
            }

            nativeClose(nativeHandle);
            IoUtils.closeQuietly(fd);
            closed = true;
        }
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            if (guard != null) {
                guard.warnIfOpen();
            }
            close();
        } finally {
            super.finalize();
        }
    }

    private InputStream getZipInputStream(ZipEntry ze) {
        if (ze.getMethod() == ZipEntry.STORED) {
            return new FDStream(fd, ze.getDataOffset(),
                    ze.getDataOffset() + ze.getSize());
        } else {
            final FDStream wrapped = new FDStream(
                    fd, ze.getDataOffset(), ze.getDataOffset() + ze.getCompressedSize());

            int bufSize = Math.max(1024, (int) Math.min(ze.getSize(), 65535L));
            return new ZipInflaterInputStream(wrapped, new Inflater(true), bufSize, ze);
        }
    }

    static final class EntryIterator implements Iterator<ZipEntry> {
        private final long iterationHandle;
        private ZipEntry nextEntry;

        EntryIterator(long nativeHandle, String prefix) throws IOException {
            iterationHandle = nativeStartIteration(nativeHandle, prefix);
        }

        public ZipEntry next() {
            if (nextEntry != null) {
                final ZipEntry ze = nextEntry;
                nextEntry = null;
                return ze;
            }

            return nativeNextEntry(iterationHandle);
        }

        public boolean hasNext() {
            if (nextEntry != null) {
                return true;
            }

            final ZipEntry ze = nativeNextEntry(iterationHandle);
            if (ze == null) {
                return false;
            }

            nextEntry = ze;
            return true;
        }

        public void remove() {
            throw new UnsupportedOperationException();
        }
    }

    private HashMap<String, byte[]> getMetaEntries() throws IOException {
        HashMap<String, byte[]> metaEntries = new HashMap<String, byte[]>();

        Iterator<ZipEntry> entryIterator = new EntryIterator(nativeHandle, "META-INF/");
        while (entryIterator.hasNext()) {
            final ZipEntry entry = entryIterator.next();
            metaEntries.put(entry.getName(), Streams.readFully(getInputStream(entry)));
        }

        return metaEntries;
    }

    static final class JarFileInputStream extends FilterInputStream {
        private final StrictJarVerifier.VerifierEntry entry;

        private long count;
        private boolean done = false;

        JarFileInputStream(InputStream is, long size, StrictJarVerifier.VerifierEntry e) {
            super(is);
            entry = e;

            count = size;
        }

        @Override
        public int read() throws IOException {
            if (done) {
                return -1;
            }
            if (count > 0) {
                int r = super.read();
                if (r != -1) {
                    entry.write(r);
                    count--;
                } else {
                    count = 0;
                }
                if (count == 0) {
                    done = true;
                    entry.verify();
                }
                return r;
            } else {
                done = true;
                entry.verify();
                return -1;
            }
        }

        @Override
        public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
            if (done) {
                return -1;
            }
            if (count > 0) {
                int r = super.read(buffer, byteOffset, byteCount);
                if (r != -1) {
                    int size = r;
                    if (count < size) {
                        size = (int) count;
                    }
                    entry.write(buffer, byteOffset, size);
                    count -= size;
                } else {
                    count = 0;
                }
                if (count == 0) {
                    done = true;
                    entry.verify();
                }
                return r;
            } else {
                done = true;
                entry.verify();
                return -1;
            }
        }

        @Override
        public int available() throws IOException {
            if (done) {
                return 0;
            }
            return super.available();
        }

        @Override
        public long skip(long byteCount) throws IOException {
            return Streams.skipByReading(this, byteCount);
        }
    }

    
@hide
/** @hide */
    public static class ZipInflaterInputStream extends InflaterInputStream {
        private final ZipEntry entry;
        private long bytesRead = 0;

        public ZipInflaterInputStream(InputStream is, Inflater inf, int bsize, ZipEntry entry) {
            super(is, inf, bsize);
            this.entry = entry;
        }

        @Override public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
            final int i;
            try {
                i = super.read(buffer, byteOffset, byteCount);
            } catch (IOException e) {
                throw new IOException("Error reading data for " + entry.getName() + " near offset "
                        + bytesRead, e);
            }
            if (i == -1) {
                if (entry.getSize() != bytesRead) {
                    throw new IOException("Size mismatch on inflated file: " + bytesRead + " vs "
                            + entry.getSize());
                }
            } else {
                bytesRead += i;
            }
            return i;
        }

        @Override public int available() throws IOException {
            if (closed) {
                // Our superclass will throw an exception, but there's a jtreg test that
                // explicitly checks that the InputStream returned from ZipFile.getInputStream
                // returns 0 even when closed.
                return 0;
            }
            return super.available() == 0 ? 0 : (int) (entry.getSize() - bytesRead);
        }
    }

    
Wrap a stream around a FileDescriptor.  The file descriptor is shared
among all streams returned by getInputStream(), so we have to synchronize
access to it.  (We can optimize this by adding buffering here to reduce
collisions.)
We could support mark/reset, but we don't currently need them.
@hide
/**
     * Wrap a stream around a FileDescriptor.  The file descriptor is shared
     * among all streams returned by getInputStream(), so we have to synchronize
     * access to it.  (We can optimize this by adding buffering here to reduce
     * collisions.)
     *
     * <p>We could support mark/reset, but we don't currently need them.
     *
     * @hide
     */
    public static class FDStream extends InputStream {
        private final FileDescriptor fd;
        private long endOffset;
        private long offset;

        public FDStream(FileDescriptor fd, long initialOffset, long endOffset) {
            this.fd = fd;
            offset = initialOffset;
            this.endOffset = endOffset;
        }

        @Override public int available() throws IOException {
            return (offset < endOffset ? 1 : 0);
        }

        @Override public int read() throws IOException {
            return Streams.readSingleByte(this);
        }

        @Override public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
            synchronized (this.fd) {
                final long length = endOffset - offset;
                if (byteCount > length) {
                    byteCount = (int) length;
                }
                try {
                    Os.lseek(fd, offset, OsConstants.SEEK_SET);
                } catch (ErrnoException e) {
                    throw new IOException(e);
                }
                int count = IoBridge.read(fd, buffer, byteOffset, byteCount);
                if (count > 0) {
                    offset += count;
                    return count;
                } else {
                    return -1;
                }
            }
        }

        @Override public long skip(long byteCount) throws IOException {
            if (byteCount > endOffset - offset) {
                byteCount = endOffset - offset;
            }
            offset += byteCount;
            return byteCount;
        }
    }

    private static native long nativeOpenJarFile(String name, int fd)
            throws IOException;
    private static native long nativeStartIteration(long nativeHandle, String prefix);
    private static native ZipEntry nativeNextEntry(long iterationHandle);
    private static native ZipEntry nativeFindEntry(long nativeHandle, String entryName);
    private static native void nativeClose(long nativeHandle);
}