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The file system driver family for ZIP and related archive file types.
Add the JAR artifact of this module to the run time class path to
make its file system drivers available for service location in the
client API modules.
/*
* Copyright (C) 2005-2013 Schlichtherle IT Services.
* All rights reserved. Use is subject to license terms.
*/
package de.schlichtherle.truezip.zip;
import static de.schlichtherle.truezip.zip.Constants.EMPTY;
import static de.schlichtherle.truezip.zip.LittleEndian.readUShort;
import static de.schlichtherle.truezip.zip.LittleEndian.writeShort;
import java.util.Map;
import java.util.TreeMap;
import javax.annotation.CheckForNull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.NotThreadSafe;
/**
* Represents a collection of {@link ExtraField Extra Fields} as they may
* be present at several locations in ZIP files.
*
* @author Christian Schlichtherle
*/
@NotThreadSafe
final class ExtraFields implements Cloneable {
/**
* The map of Extra Fields.
* Maps from Header ID [{@link Integer}] to Extra Field [{@link ExtraField}].
* Must not be {@code null}, but may be empty if no Extra Fields are used.
* The map is sorted by Header IDs in ascending order.
*/
private Map extra = new TreeMap();
/** Returns a shallow clone of this collection. */
@Override
@SuppressWarnings("AccessingNonPublicFieldOfAnotherObject")
public ExtraFields clone() {
try {
final ExtraFields clone = (ExtraFields) super.clone();
clone.extra = new TreeMap(extra);
return clone;
} catch (CloneNotSupportedException cannotHappen) {
throw new AssertionError(cannotHappen);
}
}
/** Returns the number of Extra Fields in this collection. */
int size() {
return extra.size();
}
/**
* Returns the Extra Field with the given Header ID or {@code null}
* if no such Extra Field exists.
*
* @param headerId The requested Header ID.
* @return The Extra Field with the given Header ID or {@code null}
* if no such Extra Field exists.
* @throws IllegalArgumentException If {@code headerID} is not in
* the range of {@code 0} to {@link UShort#MAX_VALUE}
* ({@value de.schlichtherle.truezip.zip.UShort#MAX_VALUE}).
*/
@CheckForNull ExtraField get(final int headerId) {
assert UShort.check(headerId);
final ExtraField ef = extra.get(headerId);
assert null == ef || ef.getHeaderId() == headerId;
return ef;
}
/**
* Stores the given Extra Field in this collection.
*
* @param ef The Extra Field to store in this collection.
* @return The Extra Field previously associated with the Header ID of
* of the given Extra Field or {@code null} if no such
* Extra Field existed.
* @throws NullPointerException If {@code ef} is {@code null}.
* @throws IllegalArgumentException If the Header ID of the given Extra
* Field is not in the range of {@code 0} to
* {@link UShort#MAX_VALUE}
* ({@value de.schlichtherle.truezip.zip.UShort#MAX_VALUE}).
*/
ExtraField add(final ExtraField ef) {
final int headerId = ef.getHeaderId();
assert UShort.check(headerId);
return extra.put(headerId, ef);
}
/**
* Removes the Extra Field with the given Header ID.
*
* @param headerId The requested Header ID.
* @return The Extra Field with the given Header ID or {@code null}
* if no such Extra Field exists.
* @throws IllegalArgumentException If {@code headerID} is not in
* the range of {@code 0} to {@link UShort#MAX_VALUE}
* ({@value de.schlichtherle.truezip.zip.UShort#MAX_VALUE}).
*/
@Nullable ExtraField remove(final int headerId) {
assert UShort.check(headerId);
final ExtraField ef = extra.remove(headerId);
assert null == ef || ef.getHeaderId() == headerId;
return ef;
}
/**
* Returns the number of bytes required to hold the Extra Fields.
*
* @return The length of the Extra Fields in bytes.
* May be {@code 0}.
* @see #getExtra
*/
int getExtraLength() {
final Map extra = this.extra;
if (extra.isEmpty())
return 0;
int l = 0;
for (ExtraField ef : extra.values())
l += 4 + ef.getDataSize();
return l;
}
/**
* Returns a protective copy of the Extra Fields.
* {@code null} is never returned.
*
* @see #getExtraLength
*/
byte[] getExtra() {
final int size = getExtraLength();
assert UShort.check(size);
if (0 == size)
return EMPTY;
final byte[] data = new byte[size];
writeTo(data, 0);
return data;
}
/**
* Deserializes this collection of extra fields from
* the data block starting at the zero based offset {@code off} with
* {@code len} bytes length in the byte array {@code buf}.
* After return, this collection does not access {@code buf} anymore
* and {@link #getDataSize} equals {@code len}.
*
* @param buf The byte array to read the data block from.
* @param off The zero based offset in the byte array where the first byte
* of the data block is read from.
* @param len The length of the data block in bytes.
* @throws IndexOutOfBoundsException If the byte array
* {@code buf} does not hold at least {@code len}
* bytes at the zero based offset {@code off}
* or if {@code len} is smaller than the extra field data requires.
* @throws IllegalArgumentException If the data block does not conform to
* the ZIP File Format Specification.
* @see #getExtraLength
*/
void readFrom(final byte[] buf, int off, final int len)
throws IndexOutOfBoundsException, IllegalArgumentException {
assert UShort.check(len);
final Map map = new TreeMap();
if (null != buf && 0 < len) {
final int end = off + len;
while (off < end) {
final int headerId = readUShort(buf, off);
off += 2;
final int dataSize = readUShort(buf, off);
off += 2;
final ExtraField ef = ExtraField.create(headerId);
ef.readFrom(buf, off, dataSize);
off += dataSize;
map.put(headerId, ef);
}
assert off == end;
}
extra = map;
}
/**
* Serializes a list of Extra Fields of {@link #getExtraLength} bytes to the
* byte array {@code data} at the zero based offset {@code off}.
* Upon return, this collection shall not access {@code data}
* subsequently.
*
* @param data The byte array to write the list of Extra Fields to.
* @param off The zero based offset in the byte array where the first byte
* of the list of Extra Fields is written to.
* @throws IndexOutOfBoundsException If the byte array
* {@code data} does not hold at least {@link #getExtraLength}
* bytes at the zero based offset {@code off}.
* @see #getExtraLength
*/
void writeTo(final byte[] data, int off)
throws IndexOutOfBoundsException {
for (final ExtraField ef : extra.values()) {
writeShort(ef.getHeaderId(), data, off);
off += 2;
writeShort(ef.getDataSize(), data, off);
off += 2;
ef.writeTo(data, off);
off += ef.getDataSize();
}
}
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