content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.util.zip;
  
  import java.io.InputStream;
  import java.io.IOException;
  import java.io.EOFException;
  import java.io.PushbackInputStream;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import static java.util.zip.ZipConstants64.*;
  import static java.util.zip.ZipUtils.*;
  
  /**
   * This class implements an input stream filter for reading files in the
   * ZIP file format. Includes support for both compressed and uncompressed
   * entries.
   *
   * @author      David Connelly
   */
  public
  class ZipInputStream extends InflaterInputStream implements ZipConstants {
      private ZipEntry entry;
      private int flag;
      private CRC32 crc = new CRC32();
      private long remaining;
      private byte[] tmpbuf = new byte[512];
  
      private static final int STORED = ZipEntry.STORED;
      private static final int DEFLATED = ZipEntry.DEFLATED;
  
      private boolean closed = false;
      // this flag is set to true after EOF has reached for
      // one entry
      private boolean entryEOF = false;
  
      private ZipCoder zc;
  
      /**
       * Check to make sure that this stream has not been closed
       */
      private void ensureOpen() throws IOException {
          if (closed) {
              throw new IOException("Stream closed");
          }
      }
  
      /**
       * Creates a new ZIP input stream.
       *
       * <p>The UTF-8 {@link Charset charset} is used to
       * decode the entry names.
       *
       * @param in the actual input stream
       */
      public ZipInputStream(InputStream in) {
          this(in, StandardCharsets.UTF_8);
      }
  
      /**
       * Creates a new ZIP input stream.
       *
       * @param in the actual input stream
       *
       * @param charset
       *        The {@linkplain Charset charset} to be
       *        used to decode the ZIP entry name (ignored if the
       *        <a href="package-summary.html#lang_encoding"> language
       *        encoding bit</a> of the ZIP entry's general purpose bit
       *        flag is set).
       *
       * @since 1.7
       */
      public ZipInputStream(InputStream in, Charset charset) {
          super(new PushbackInputStream(in, 512), new Inflater(true), 512);
          // Android-changed: Unconditionally close external inflaters (b/26462400)
          // usesDefaultInflater = true;
          if(in == null) {
              throw new NullPointerException("in is null");
          }
          if (charset == null)
              throw new NullPointerException("charset is null");
          this.zc = ZipCoder.get(charset);
      }
  
      /**
       * Reads the next ZIP file entry and positions the stream at the
       * beginning of the entry data.
       * @return the next ZIP file entry, or null if there are no more entries
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       */
      public ZipEntry getNextEntry() throws IOException {
          ensureOpen();
          if (entry != null) {
              closeEntry();
          }
          crc.reset();
          inf.reset();
          if ((entry = readLOC()) == null) {
              return null;
          }
          // Android-changed: Return more accurate value from available().
          // Initialize the remaining field with the number of bytes that can be read from the entry
          // for both uncompressed and compressed entries so that it can be used to provide a more
          // accurate return value for available().
          // if (entry.method == STORED) {
          if (entry.method == STORED || entry.method == DEFLATED) {
              remaining = entry.size;
          }
          entryEOF = false;
          return entry;
      }
  
      /**
       * Closes the current ZIP entry and positions the stream for reading the
       * next entry.
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       */
      public void closeEntry() throws IOException {
          ensureOpen();
          while (read(tmpbuf, 0, tmpbuf.length) != -1) ;
          entryEOF = true;
      }
  
      /**
       * Returns 0 after EOF has reached for the current entry data,
       * otherwise always return 1.
       * <p>
       * Programs should not count on this method to return the actual number
       * of bytes that could be read without blocking.
       *
       * @return     1 before EOF and 0 after EOF has reached for current entry.
       * @exception  IOException  if an I/O error occurs.
       *
       */
      public int available() throws IOException {
          ensureOpen();
          // Android-changed: Return more accurate value from available().
          // Tracks the remaining bytes in order to return a more accurate value for the available
          // bytes. Given an entry of size N both Android and upstream will return 1 until N bytes
          // have been read at which point Android will return 0 and upstream will return 1.
          // Upstream will only return 0 after an attempt to read a byte fails because the EOF has
          // been reached. See http://b/111439440 for more details.
          // if (entryEOF) {
          if (entryEOF || (entry != null && remaining == 0)) {
              return 0;
          } else {
              return 1;
          }
      }
  
      /**
       * Reads from the current ZIP entry into an array of bytes.
       * If <code>len</code> is not zero, the method
       * blocks until some input is available; otherwise, no
       * bytes are read and <code>0</code> is returned.
       * @param b the buffer into which the data is read
       * @param off the start offset in the destination array <code>b</code>
       * @param len the maximum number of bytes read
       * @return the actual number of bytes read, or -1 if the end of the
       *         entry is reached
       * @exception  NullPointerException if <code>b</code> is <code>null</code>.
       * @exception  IndexOutOfBoundsException if <code>off</code> is negative,
       * <code>len</code> is negative, or <code>len</code> is greater than
       * <code>b.length - off</code>
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       */
      public int read(byte[] b, int off, int len) throws IOException {
          ensureOpen();
          if (off < 0 || len < 0 || off > b.length - len) {
              throw new IndexOutOfBoundsException();
          } else if (len == 0) {
              return 0;
          }
  
          if (entry == null) {
              return -1;
          }
          switch (entry.method) {
          case DEFLATED:
              len = super.read(b, off, len);
              if (len == -1) {
                  readEnd(entry);
                  entryEOF = true;
                  entry = null;
              } else {
                  crc.update(b, off, len);
                  // Android-added: Return more accurate value from available().
                  // Update the remaining field so it is an accurate count of the number of bytes
                  // remaining in this stream, after deflation.
                  remaining -= len;
              }
              return len;
          case STORED:
              if (remaining <= 0) {
                  entryEOF = true;
                  entry = null;
                  return -1;
              }
              if (len > remaining) {
                  len = (int)remaining;
              }
              len = in.read(b, off, len);
              if (len == -1) {
                  throw new ZipException("unexpected EOF");
              }
              crc.update(b, off, len);
              remaining -= len;
              if (remaining == 0 && entry.crc != crc.getValue()) {
                  throw new ZipException(
                      "invalid entry CRC (expected 0x" + Long.toHexString(entry.crc) +
                      " but got 0x" + Long.toHexString(crc.getValue()) + ")");
              }
              return len;
          default:
              throw new ZipException("invalid compression method");
          }
      }
  
      /**
       * Skips specified number of bytes in the current ZIP entry.
       * @param n the number of bytes to skip
       * @return the actual number of bytes skipped
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       * @exception IllegalArgumentException if {@code n < 0}
       */
      public long skip(long n) throws IOException {
          if (n < 0) {
              throw new IllegalArgumentException("negative skip length");
          }
          ensureOpen();
          int max = (int)Math.min(n, Integer.MAX_VALUE);
          int total = 0;
          while (total < max) {
              int len = max - total;
              if (len > tmpbuf.length) {
                  len = tmpbuf.length;
              }
              len = read(tmpbuf, 0, len);
              if (len == -1) {
                  entryEOF = true;
                  break;
              }
              total += len;
          }
          return total;
      }
  
      /**
       * Closes this input stream and releases any system resources associated
       * with the stream.
       * @exception IOException if an I/O error has occurred
       */
      public void close() throws IOException {
          if (!closed) {
              super.close();
              closed = true;
          }
      }
  
      private byte[] b = new byte[256];
  
      /*
       * Reads local file (LOC) header for next entry.
       */
      private ZipEntry readLOC() throws IOException {
          try {
              readFully(tmpbuf, 0, LOCHDR);
          } catch (EOFException e) {
              return null;
          }
          if (get32(tmpbuf, 0) != LOCSIG) {
              return null;
          }
          // get flag first, we need check EFS.
          flag = get16(tmpbuf, LOCFLG);
          // get the entry name and create the ZipEntry first
          int len = get16(tmpbuf, LOCNAM);
          int blen = b.length;
          if (len > blen) {
              do {
                  blen = blen * 2;
              } while (len > blen);
              b = new byte[blen];
          }
          readFully(b, 0, len);
          // Force to use UTF-8 if the EFS bit is ON, even the cs is NOT UTF-8
          ZipEntry e = createZipEntry(((flag & EFS) != 0)
                                      ? zc.toStringUTF8(b, len)
                                      : zc.toString(b, len));
          // now get the remaining fields for the entry
          if ((flag & 1) == 1) {
              throw new ZipException("encrypted ZIP entry not supported");
          }
          e.method = get16(tmpbuf, LOCHOW);
          e.xdostime = get32(tmpbuf, LOCTIM);
          if ((flag & 8) == 8) {
              // Android-Changed: Remove the requirement that only DEFLATED entries
              // can have data descriptors. This is not required by the ZIP spec and
              // is inconsistent with the behaviour of ZipFile and versions of Android
              // prior to Android N.
              //
              // /* "Data Descriptor" present */
              // if (e.method != DEFLATED) {
              //     throw new ZipException(
              //             "only DEFLATED entries can have EXT descriptor");
              // }
          } else {
              e.crc = get32(tmpbuf, LOCCRC);
              e.csize = get32(tmpbuf, LOCSIZ);
              e.size = get32(tmpbuf, LOCLEN);
          }
          len = get16(tmpbuf, LOCEXT);
          if (len > 0) {
              byte[] extra = new byte[len];
              readFully(extra, 0, len);
              e.setExtra0(extra,
                          e.csize == ZIP64_MAGICVAL || e.size == ZIP64_MAGICVAL);
          }
          return e;
      }
  
      /**
       * Creates a new <code>ZipEntry</code> object for the specified
       * entry name.
       *
       * @param name the ZIP file entry name
       * @return the ZipEntry just created
       */
      protected ZipEntry createZipEntry(String name) {
          return new ZipEntry(name);
      }
  
      /*
       * Reads end of deflated entry as well as EXT descriptor if present.
       */
      private void readEnd(ZipEntry e) throws IOException {
          int n = inf.getRemaining();
          if (n > 0) {
              ((PushbackInputStream)in).unread(buf, len - n, n);
          }
          if ((flag & 8) == 8) {
              /* "Data Descriptor" present */
              if (inf.getBytesWritten() > ZIP64_MAGICVAL ||
                  inf.getBytesRead() > ZIP64_MAGICVAL) {
                  // ZIP64 format
                  readFully(tmpbuf, 0, ZIP64_EXTHDR);
                  long sig = get32(tmpbuf, 0);
                  if (sig != EXTSIG) { // no EXTSIG present
                      e.crc = sig;
                      e.csize = get64(tmpbuf, ZIP64_EXTSIZ - ZIP64_EXTCRC);
                      e.size = get64(tmpbuf, ZIP64_EXTLEN - ZIP64_EXTCRC);
                      ((PushbackInputStream)in).unread(
                          tmpbuf, ZIP64_EXTHDR - ZIP64_EXTCRC - 1, ZIP64_EXTCRC);
                  } else {
                      e.crc = get32(tmpbuf, ZIP64_EXTCRC);
                      e.csize = get64(tmpbuf, ZIP64_EXTSIZ);
                      e.size = get64(tmpbuf, ZIP64_EXTLEN);
                  }
              } else {
                  readFully(tmpbuf, 0, EXTHDR);
                  long sig = get32(tmpbuf, 0);
                  if (sig != EXTSIG) { // no EXTSIG present
                      e.crc = sig;
                      e.csize = get32(tmpbuf, EXTSIZ - EXTCRC);
                      e.size = get32(tmpbuf, EXTLEN - EXTCRC);
                      ((PushbackInputStream)in).unread(
                                                 tmpbuf, EXTHDR - EXTCRC - 1, EXTCRC);
                  } else {
                      e.crc = get32(tmpbuf, EXTCRC);
                      e.csize = get32(tmpbuf, EXTSIZ);
                      e.size = get32(tmpbuf, EXTLEN);
                  }
              }
          }
          if (e.size != inf.getBytesWritten()) {
              throw new ZipException(
                  "invalid entry size (expected " + e.size +
                  " but got " + inf.getBytesWritten() + " bytes)");
          }
          if (e.csize != inf.getBytesRead()) {
              throw new ZipException(
                  "invalid entry compressed size (expected " + e.csize +
                  " but got " + inf.getBytesRead() + " bytes)");
          }
          if (e.crc != crc.getValue()) {
              throw new ZipException(
                  "invalid entry CRC (expected 0x" + Long.toHexString(e.crc) +
                  " but got 0x" + Long.toHexString(crc.getValue()) + ")");
          }
      }
  
      /*
       * Reads bytes, blocking until all bytes are read.
       */
      private void readFully(byte[] b, int off, int len) throws IOException {
          while (len > 0) {
              int n = in.read(b, off, len);
              if (n == -1) {
                  throw new EOFException();
              }
              off += n;
              len -= n;
          }
      }
  
  }
  