A zip file (or "archive") is a collection of (possibly) compressed files. * When reading from a {@code ZipInputStream}, you call {@link #getNextEntry} * which returns a {@link ZipEntry} of metadata corresponding to the userdata that follows. * When you appear to have hit the end of this stream (which is really just the end of the current * entry's userdata), call {@code getNextEntry} again. When it returns null, * there are no more entries in the input file. * *
Although {@code InflaterInputStream} can only read compressed zip * entries, this class can read non-compressed entries as well. * *
Use {@link ZipFile} if you need random access to entries by name, but use this class * if you just want to iterate over all entries. * *
Using {@code ZipInputStream} is a little more complicated than {@link GZIPInputStream} * because zip files are containers that can contain multiple files. This code pulls all the * files out of a zip file, similar to the {@code unzip(1)} utility. *
* InputStream is = ...
* ZipInputStream zis = new ZipInputStream(new BufferedInputStream(is));
* try {
* ZipEntry ze;
* while ((ze = zis.getNextEntry()) != null) {
* ByteArrayOutputStream baos = new ByteArrayOutputStream();
* byte[] buffer = new byte[1024];
* int count;
* while ((count = zis.read(buffer)) != -1) {
* baos.write(buffer, 0, count);
* }
* String filename = ze.getName();
* byte[] bytes = baos.toByteArray();
* // do something with 'filename' and 'bytes'...
* }
* } finally {
* zis.close();
* }
*
*/
public class ZipInputStream extends InflaterInputStream implements ZipConstants {
private static final int ZIPLocalHeaderVersionNeeded = 20;
private boolean entriesEnd = false;
private boolean hasDD = false;
private int entryIn = 0;
private int inRead, lastRead = 0;
private ZipEntry currentEntry;
private final byte[] hdrBuf = new byte[LOCHDR - LOCVER];
private final CRC32 crc = new CRC32();
private byte[] nameBuf = new byte[256];
private char[] charBuf = new char[256];
/**
* Constructs a new {@code ZipInputStream} to read zip entries from the given input stream.
*/
public ZipInputStream(InputStream stream) {
super(new PushbackInputStream(stream, BUF_SIZE), new Inflater(true));
if (stream == null) {
throw new NullPointerException("stream == null");
}
}
/**
* Closes this {@code ZipInputStream}.
*
* @throws IOException
* if an {@code IOException} occurs.
*/
@Override
public void close() throws IOException {
if (!closed) {
closeEntry(); // Close the current entry
super.close();
}
}
/**
* Closes the current zip entry and prepares to read the next entry.
*
* @throws IOException
* if an {@code IOException} occurs.
*/
public void closeEntry() throws IOException {
checkClosed();
if (currentEntry == null) {
return;
}
if (currentEntry instanceof java.util.jar.JarEntry) {
Attributes temp = ((JarEntry) currentEntry).getAttributes();
if (temp != null && temp.containsKey("hidden")) {
return;
}
}
/*
* The following code is careful to leave the ZipInputStream in a
* consistent state, even when close() results in an exception. It does
* so by:
* - pushing bytes back into the source stream
* - reading a data descriptor footer from the source stream
* - resetting fields that manage the entry being closed
*/
// Ensure all entry bytes are read
Exception failure = null;
try {
Streams.skipAll(this);
} catch (Exception e) {
failure = e;
}
int inB, out;
if (currentEntry.compressionMethod == ZipEntry.DEFLATED) {
inB = inf.getTotalIn();
out = inf.getTotalOut();
} else {
inB = inRead;
out = inRead;
}
int diff = entryIn - inB;
// Pushback any required bytes
if (diff != 0) {
((PushbackInputStream) in).unread(buf, len - diff, diff);
}
try {
readAndVerifyDataDescriptor(inB, out);
} catch (Exception e) {
if (failure == null) { // otherwise we're already going to throw
failure = e;
}
}
inf.reset();
lastRead = inRead = entryIn = len = 0;
crc.reset();
currentEntry = null;
if (failure != null) {
if (failure instanceof IOException) {
throw (IOException) failure;
} else if (failure instanceof RuntimeException) {
throw (RuntimeException) failure;
}
AssertionError error = new AssertionError();
error.initCause(failure);
throw error;
}
}
private void readAndVerifyDataDescriptor(int inB, int out) throws IOException {
if (hasDD) {
Streams.readFully(in, hdrBuf, 0, EXTHDR);
int sig = Memory.peekInt(hdrBuf, 0, ByteOrder.LITTLE_ENDIAN);
if (sig != (int) EXTSIG) {
throw new ZipException(String.format("unknown format (EXTSIG=%x)", sig));
}
currentEntry.crc = ((long) Memory.peekInt(hdrBuf, EXTCRC, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
currentEntry.compressedSize = ((long) Memory.peekInt(hdrBuf, EXTSIZ, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
currentEntry.size = ((long) Memory.peekInt(hdrBuf, EXTLEN, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
}
if (currentEntry.crc != crc.getValue()) {
throw new ZipException("CRC mismatch");
}
if (currentEntry.compressedSize != inB || currentEntry.size != out) {
throw new ZipException("Size mismatch");
}
}
/**
* Returns the next entry from this {@code ZipInputStream} or {@code null} if
* no more entries are present.
*
* @throws IOException if an {@code IOException} occurs.
*/
public ZipEntry getNextEntry() throws IOException {
closeEntry();
if (entriesEnd) {
return null;
}
// Read the signature to see whether there's another local file header.
Streams.readFully(in, hdrBuf, 0, 4);
int hdr = Memory.peekInt(hdrBuf, 0, ByteOrder.LITTLE_ENDIAN);
if (hdr == CENSIG) {
entriesEnd = true;
return null;
}
if (hdr != LOCSIG) {
return null;
}
// Read the local file header.
Streams.readFully(in, hdrBuf, 0, (LOCHDR - LOCVER));
int version = peekShort(0) & 0xff;
if (version > ZIPLocalHeaderVersionNeeded) {
throw new ZipException("Cannot read local header version " + version);
}
int flags = peekShort(LOCFLG - LOCVER);
if ((flags & ZipFile.GPBF_UNSUPPORTED_MASK) != 0) {
throw new ZipException("Invalid General Purpose Bit Flag: " + flags);
}
hasDD = ((flags & ZipFile.GPBF_DATA_DESCRIPTOR_FLAG) != 0);
int ceLastModifiedTime = peekShort(LOCTIM - LOCVER);
int ceLastModifiedDate = peekShort(LOCTIM - LOCVER + 2);
int ceCompressionMethod = peekShort(LOCHOW - LOCVER);
long ceCrc = 0, ceCompressedSize = 0, ceSize = -1;
if (!hasDD) {
ceCrc = ((long) Memory.peekInt(hdrBuf, LOCCRC - LOCVER, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
ceCompressedSize = ((long) Memory.peekInt(hdrBuf, LOCSIZ - LOCVER, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
ceSize = ((long) Memory.peekInt(hdrBuf, LOCLEN - LOCVER, ByteOrder.LITTLE_ENDIAN)) & 0xffffffffL;
}
int nameLength = peekShort(LOCNAM - LOCVER);
if (nameLength == 0) {
throw new ZipException("Entry is not named");
}
int extraLength = peekShort(LOCEXT - LOCVER);
if (nameLength > nameBuf.length) {
nameBuf = new byte[nameLength];
// The bytes are modified UTF-8, so the number of chars will always be less than or
// equal to the number of bytes. It's fine if this buffer is too long.
charBuf = new char[nameLength];
}
Streams.readFully(in, nameBuf, 0, nameLength);
currentEntry = createZipEntry(ModifiedUtf8.decode(nameBuf, charBuf, 0, nameLength));
currentEntry.time = ceLastModifiedTime;
currentEntry.modDate = ceLastModifiedDate;
currentEntry.setMethod(ceCompressionMethod);
if (ceSize != -1) {
currentEntry.setCrc(ceCrc);
currentEntry.setSize(ceSize);
currentEntry.setCompressedSize(ceCompressedSize);
}
if (extraLength > 0) {
byte[] extraData = new byte[extraLength];
Streams.readFully(in, extraData, 0, extraLength);
currentEntry.setExtra(extraData);
}
return currentEntry;
}
private int peekShort(int offset) {
return Memory.peekShort(hdrBuf, offset, ByteOrder.LITTLE_ENDIAN) & 0xffff;
}
/**
* Reads up to {@code byteCount} uncompressed bytes into the buffer
* starting at {@code byteOffset}. Returns the number of bytes actually read, or -1.
*/
@Override
public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
checkClosed();
Arrays.checkOffsetAndCount(buffer.length, byteOffset, byteCount);
if (inf.finished() || currentEntry == null) {
return -1;
}
if (currentEntry.compressionMethod == ZipEntry.STORED) {
int csize = (int) currentEntry.size;
if (inRead >= csize) {
return -1;
}
if (lastRead >= len) {
lastRead = 0;
if ((len = in.read(buf)) == -1) {
eof = true;
return -1;
}
entryIn += len;
}
int toRead = byteCount > (len - lastRead) ? len - lastRead : byteCount;
if ((csize - inRead) < toRead) {
toRead = csize - inRead;
}
System.arraycopy(buf, lastRead, buffer, byteOffset, toRead);
lastRead += toRead;
inRead += toRead;
crc.update(buffer, byteOffset, toRead);
return toRead;
}
if (inf.needsInput()) {
fill();
if (len > 0) {
entryIn += len;
}
}
int read;
try {
read = inf.inflate(buffer, byteOffset, byteCount);
} catch (DataFormatException e) {
throw new ZipException(e.getMessage());
}
if (read == 0 && inf.finished()) {
return -1;
}
crc.update(buffer, byteOffset, read);
return read;
}
@Override
public int available() throws IOException {
checkClosed();
// The InflaterInputStream contract says we must only return 0 or 1.
return (currentEntry == null || inRead < currentEntry.size) ? 1 : 0;
}
/**
* creates a {@link ZipEntry } with the given name.
*
* @param name
* the name of the entry.
* @return the created {@code ZipEntry}.
*/
protected ZipEntry createZipEntry(String name) {
return new ZipEntry(name);
}
private void checkClosed() throws IOException {
if (closed) {
throw new IOException("Stream is closed");
}
}
}