// Copyright 2015 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.android.ziputils;
import static java.nio.ByteOrder.LITTLE_ENDIAN;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.nio.ByteBuffer;
/**
* Provides a view of a central directory entry.
*/
public class DirectoryEntry extends View<DirectoryEntry> {
/**
* Returns a {@code DirectoryEntry of the given buffer. The buffer is assumed to contain a
* valid "central directory entry" record beginning at the buffers current position.
*
* @param buffer containing the data of a "central directory entry" record.
* @return a {@code DirectoryEntry} of the data at the current position of the given byte
* buffer.
*/
public static DirectoryEntry viewOf(ByteBuffer buffer) {
DirectoryEntry view = new DirectoryEntry(buffer.slice());
int size = view.getSize();
buffer.position(buffer.position() + size);
view.buffer.position(0).limit(size);
return view;
}
private DirectoryEntry(ByteBuffer buffer) {
super(buffer);
}
/**
* Creates a {@code DirectoryEntry} with a heap allocated buffer. Apart from the signature,
* and provided extra data and comment data, the returned object is uninitialized.
*
* @param name entry file name. Cannot be {@code null}.
* @param extraData extra data, or {@code null}
* @param comment zip file comment, or {@code null}.
* @return a {@code DirectoryEntry} with a heap allocated buffer.
*/
public static DirectoryEntry allocate(String name, byte[] extraData, String comment) {
byte[] nameData = name.getBytes(UTF_8);
byte[] commentData = comment != null ? comment.getBytes(UTF_8) : EMPTY;
if (extraData == null) {
extraData = EMPTY;
}
int size = SIZE + nameData.length + extraData.length + commentData.length;
ByteBuffer buffer = ByteBuffer.allocate(size).order(LITTLE_ENDIAN);
return new DirectoryEntry(buffer).init(nameData, extraData, commentData, size);
}
/**
* Creates a {@code DirectoryEntry} over a writable buffer. The given buffers position is
* advanced by the number of bytes consumed by the view. Apart from the signature, and
* provided extra data and comment data, the returned view is uninitialized.
*
* @param buffer buffer to hold data for the "central directory entry" record.
* @param name entry file name. Cannot be {@code null}.
* @param extraData extra data, or {@code null}
* @param comment zip file global comment, or {@code null}.
* @return a {@code DirectoryEntry} with a heap allocated buffer.
*/
public static DirectoryEntry view(ByteBuffer buffer, String name, byte[] extraData,
String comment) {
byte[] nameData = name.getBytes(UTF_8);
byte[] commentData = comment != null ? comment.getBytes(UTF_8) : EMPTY;
if (extraData == null) {
extraData = EMPTY;
}
int size = SIZE + nameData.length + extraData.length + commentData.length;
DirectoryEntry view = new DirectoryEntry(buffer.slice()).init(nameData, extraData,
commentData, size);
buffer.position(buffer.position() + size);
return view;
}
/**
* Copies this {@code DirectoryEntry} into a heap allocated buffer, overwriting path name,
* extra data and comment with the given values.
*
* @param name entry file name. Cannot be {@code null}.
* @param extraData extra data, or {@code null}
* @param comment zip file global comment, or {@code null}.
* @return a {@code DirectoryEntry} with a heap allocated buffer, initialized with the
* given values, and otherwise as a copy of this object.
*/
public DirectoryEntry clone(String name, byte[] extraData, String comment) {
return DirectoryEntry.allocate(name, extraData, comment).copy(this, CENOFF, CENCRC, CENSIZ,
CENLEN, CENFLG, CENHOW, CENTIM, CENVER, CENVER, CENDSK, CENATX, CENATT);
}
/**
* Copies this {@code DirectoryEntry} into a writable buffer. The copy is made at the
* buffer's current position, and the position is advanced, by the size of the copy.
*
* @param buffer buffer to hold data for the copy.
* @return a {@code DirectoryEntry} backed by the given buffer.
*/
public DirectoryEntry copy(ByteBuffer buffer) {
int size = getSize();
DirectoryEntry view = new DirectoryEntry(buffer.slice());
this.buffer.rewind();
view.buffer.put(this.buffer).flip();
buffer.position(buffer.position() + size);
this.buffer.rewind().limit(size);
return view;
}
private DirectoryEntry init(byte[] name, byte[] extra, byte[] comment, int size) {
buffer.putInt(0, SIGNATURE);
set(CENNAM, (short) name.length);
set(CENEXT, (short) extra.length);
set(CENCOM, (short) comment.length);
buffer.position(SIZE);
buffer.put(name);
if (extra.length > 0) {
buffer.put(extra);
}
if (comment.length > 0) {
buffer.put(comment);
}
buffer.position(0).limit(size);
return this;
}
public final int getSize() {
return SIZE + get(CENNAM) + get(CENEXT) + get(CENCOM);
}
/**
* Directory entry signature.
*/
public static final int SIGNATURE = 0x02014b50; // 33639248L
/**
* Size of directory entry, not including variable data.
* Also the offset of the entry filename.
*/
public static final int SIZE = 46;
/**
* For accessing the directory entry signature, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENSIG = new IntFieldId<>(0);
/**
* For accessing the "made by version" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENVEM = new ShortFieldId<>(4);
/**
* For accessing the "version needed" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENVER = new ShortFieldId<>(6);
/**
* For accessing the "flags" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENFLG = new ShortFieldId<>(8);
/**
* For accessing the "method" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENHOW = new ShortFieldId<>(10);
/**
* For accessing the "modified time" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENTIM = new IntFieldId<>(12);
/**
* For accessing the "crc" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENCRC = new IntFieldId<>(16);
/**
* For accessing the "compressed size" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENSIZ = new IntFieldId<>(20);
/**
* For accessing the "uncompressed size" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENLEN = new IntFieldId<>(24);
/**
* For accessing the "filename length" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENNAM = new ShortFieldId<>(28);
/**
* For accessing the "extra data length" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENEXT = new ShortFieldId<>(30);
/**
* For accessing the "file comment length" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENCOM = new ShortFieldId<>(32);
/**
* For accessing the "disk number" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENDSK = new ShortFieldId<>(34);
/**
* For accessing the "internal attributes" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.ShortFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.ShortFieldId, short)}
* methods.
*/
public static final ShortFieldId<DirectoryEntry> CENATT = new ShortFieldId<>(36);
/**
* For accessing the "external attributes" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENATX = new IntFieldId<>(38);
/**
* For accessing the "local file header offset" directory entry field, with the
* {@link View#get(com.google.devtools.build.android.ziputils.View.IntFieldId)}
* and {@link View#set(com.google.devtools.build.android.ziputils.View.IntFieldId, int)}
* methods.
*/
public static final IntFieldId<DirectoryEntry> CENOFF = new IntFieldId<>(42);
/**
* Returns the filename of this entry.
*/
public final String getFilename() {
return getString(SIZE, get(CENNAM));
}
/**
* Returns the extra data of this entry.
* @return a byte array with 0 or more bytes.
*/
public final byte[] getExtraData() {
return getBytes(SIZE + get(CENNAM), get(CENEXT));
}
/**
* Return the comment of this entry.
* @return a string with 0 or more characters.
*/
public final String getComment() {
return getString(SIZE + get(CENNAM) + get(CENEXT), get(CENCOM));
}
/**
* Returns entry data size, based on directory entry information. For a valid zip file, this will
* be the correct size of of the entry data.
* @return if the {@link #CENHOW} field is 0, returns the value of the
* {@link #CENLEN} field (uncompressed size), otherwise returns the value of
* the {@link #CENSIZ} field (compressed size).
*/
public int dataSize() {
return get(CENHOW) == 0 ? get(CENLEN) : get(CENSIZ);
}
}