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Apache Commons Compress software defines an API for working with
compression and archive formats. These include: bzip2, gzip, pack200,
lzma, xz, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4,
Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.compress.archivers.zip;
import java.io.IOException;
import java.math.BigInteger;
import java.util.Calendar;
import java.util.Date;
import java.util.zip.CRC32;
import java.util.zip.ZipEntry;
/**
* Utility class for handling DOS and Java time conversions.
* @Immutable
*/
public abstract class ZipUtil {
/**
* Smallest date/time ZIP can handle.
*/
private static final byte[] DOS_TIME_MIN = ZipLong.getBytes(0x00002100L);
/**
* Convert a Date object to a DOS date/time field.
* @param time the Date to convert
* @return the date as a ZipLong
*/
public static ZipLong toDosTime(Date time) {
return new ZipLong(toDosTime(time.getTime()));
}
/**
* Convert a Date object to a DOS date/time field.
*
* Stolen from InfoZip's fileio.c
* @param t number of milliseconds since the epoch
* @return the date as a byte array
*/
public static byte[] toDosTime(long t) {
Calendar c = Calendar.getInstance();
c.setTimeInMillis(t);
int year = c.get(Calendar.YEAR);
if (year < 1980) {
return copy(DOS_TIME_MIN); // stop callers from changing the array
}
int month = c.get(Calendar.MONTH) + 1;
long value = ((year - 1980) << 25)
| (month << 21)
| (c.get(Calendar.DAY_OF_MONTH) << 16)
| (c.get(Calendar.HOUR_OF_DAY) << 11)
| (c.get(Calendar.MINUTE) << 5)
| (c.get(Calendar.SECOND) >> 1);
return ZipLong.getBytes(value);
}
/**
* Assumes a negative integer really is a positive integer that
* has wrapped around and re-creates the original value.
*
* @param i the value to treat as unsigned int.
* @return the unsigned int as a long.
*/
public static long adjustToLong(int i) {
if (i < 0) {
return 2 * ((long) Integer.MAX_VALUE) + 2 + i;
} else {
return i;
}
}
/**
* Reverses a byte[] array. Reverses in-place (thus provided array is
* mutated), but also returns same for convenience.
*
* @param array to reverse (mutated in-place, but also returned for
* convenience).
*
* @return the reversed array (mutated in-place, but also returned for
* convenience).
* @since 1.5
*/
public static byte[] reverse(final byte[] array) {
final int z = array.length - 1; // position of last element
for (int i = 0; i < array.length / 2; i++) {
byte x = array[i];
array[i] = array[z - i];
array[z - i] = x;
}
return array;
}
/**
* Converts a BigInteger into a long, and blows up
* (NumberFormatException) if the BigInteger is too big.
*
* @param big BigInteger to convert.
* @return long representation of the BigInteger.
*/
static long bigToLong(BigInteger big) {
if (big.bitLength() <= 63) { // bitLength() doesn't count the sign bit.
return big.longValue();
} else {
throw new NumberFormatException("The BigInteger cannot fit inside a 64 bit java long: [" + big + "]");
}
}
/**
*
* Converts a long into a BigInteger. Negative numbers between -1 and
* -2^31 are treated as unsigned 32 bit (e.g., positive) integers.
* Negative numbers below -2^31 cause an IllegalArgumentException
* to be thrown.
*
*
* @param l long to convert to BigInteger.
* @return BigInteger representation of the provided long.
*/
static BigInteger longToBig(long l) {
if (l < Integer.MIN_VALUE) {
throw new IllegalArgumentException("Negative longs < -2^31 not permitted: [" + l + "]");
} else if (l < 0 && l >= Integer.MIN_VALUE) {
// If someone passes in a -2, they probably mean 4294967294
// (For example, Unix UID/GID's are 32 bit unsigned.)
l = ZipUtil.adjustToLong((int) l);
}
return BigInteger.valueOf(l);
}
/**
* Converts a signed byte into an unsigned integer representation
* (e.g., -1 becomes 255).
*
* @param b byte to convert to int
* @return int representation of the provided byte
* @since 1.5
*/
public static int signedByteToUnsignedInt(byte b) {
if (b >= 0) {
return b;
} else {
return 256 + b;
}
}
/**
* Converts an unsigned integer to a signed byte (e.g., 255 becomes -1).
*
* @param i integer to convert to byte
* @return byte representation of the provided int
* @throws IllegalArgumentException if the provided integer is not inside the range [0,255].
* @since 1.5
*/
public static byte unsignedIntToSignedByte(int i) {
if (i > 255 || i < 0) {
throw new IllegalArgumentException("Can only convert non-negative integers between [0,255] to byte: [" + i + "]");
}
if (i < 128) {
return (byte) i;
} else {
return (byte) (i - 256);
}
}
/**
* Convert a DOS date/time field to a Date object.
*
* @param zipDosTime contains the stored DOS time.
* @return a Date instance corresponding to the given time.
*/
public static Date fromDosTime(ZipLong zipDosTime) {
long dosTime = zipDosTime.getValue();
return new Date(dosToJavaTime(dosTime));
}
/**
* Converts DOS time to Java time (number of milliseconds since
* epoch).
*/
public static long dosToJavaTime(long dosTime) {
Calendar cal = Calendar.getInstance();
// CheckStyle:MagicNumberCheck OFF - no point
cal.set(Calendar.YEAR, (int) ((dosTime >> 25) & 0x7f) + 1980);
cal.set(Calendar.MONTH, (int) ((dosTime >> 21) & 0x0f) - 1);
cal.set(Calendar.DATE, (int) (dosTime >> 16) & 0x1f);
cal.set(Calendar.HOUR_OF_DAY, (int) (dosTime >> 11) & 0x1f);
cal.set(Calendar.MINUTE, (int) (dosTime >> 5) & 0x3f);
cal.set(Calendar.SECOND, (int) (dosTime << 1) & 0x3e);
// CheckStyle:MagicNumberCheck ON
return cal.getTime().getTime();
}
/**
* If the entry has Unicode*ExtraFields and the CRCs of the
* names/comments match those of the extra fields, transfer the
* known Unicode values from the extra field.
*/
static void setNameAndCommentFromExtraFields(ZipArchiveEntry ze,
byte[] originalNameBytes,
byte[] commentBytes) {
UnicodePathExtraField name = (UnicodePathExtraField)
ze.getExtraField(UnicodePathExtraField.UPATH_ID);
String originalName = ze.getName();
String newName = getUnicodeStringIfOriginalMatches(name,
originalNameBytes);
if (newName != null && !originalName.equals(newName)) {
ze.setName(newName);
}
if (commentBytes != null && commentBytes.length > 0) {
UnicodeCommentExtraField cmt = (UnicodeCommentExtraField)
ze.getExtraField(UnicodeCommentExtraField.UCOM_ID);
String newComment =
getUnicodeStringIfOriginalMatches(cmt, commentBytes);
if (newComment != null) {
ze.setComment(newComment);
}
}
}
/**
* If the stored CRC matches the one of the given name, return the
* Unicode name of the given field.
*
* If the field is null or the CRCs don't match, return null
* instead.
*/
private static
String getUnicodeStringIfOriginalMatches(AbstractUnicodeExtraField f,
byte[] orig) {
if (f != null) {
CRC32 crc32 = new CRC32();
crc32.update(orig);
long origCRC32 = crc32.getValue();
if (origCRC32 == f.getNameCRC32()) {
try {
return ZipEncodingHelper
.UTF8_ZIP_ENCODING.decode(f.getUnicodeName());
} catch (IOException ex) {
// UTF-8 unsupported? should be impossible the
// Unicode*ExtraField must contain some bad bytes
// TODO log this anywhere?
return null;
}
}
}
return null;
}
/**
* Create a copy of the given array - or return null if the
* argument is null.
*/
static byte[] copy(byte[] from) {
if (from != null) {
byte[] to = new byte[from.length];
System.arraycopy(from, 0, to, 0, to.length);
return to;
}
return null;
}
/**
* Whether this library is able to read or write the given entry.
*/
static boolean canHandleEntryData(ZipArchiveEntry entry) {
return supportsEncryptionOf(entry) && supportsMethodOf(entry);
}
/**
* Whether this library supports the encryption used by the given
* entry.
*
* @return true if the entry isn't encrypted at all
*/
private static boolean supportsEncryptionOf(ZipArchiveEntry entry) {
return !entry.getGeneralPurposeBit().usesEncryption();
}
/**
* Whether this library supports the compression method used by
* the given entry.
*
* @return true if the compression method is STORED or DEFLATED
*/
private static boolean supportsMethodOf(ZipArchiveEntry entry) {
return entry.getMethod() == ZipEntry.STORED
|| entry.getMethod() == ZipEntry.DEFLATED;
}
/**
* Checks whether the entry requires features not (yet) supported
* by the library and throws an exception if it does.
*/
static void checkRequestedFeatures(ZipArchiveEntry ze)
throws UnsupportedZipFeatureException {
if (!supportsEncryptionOf(ze)) {
throw
new UnsupportedZipFeatureException(UnsupportedZipFeatureException
.Feature.ENCRYPTION, ze);
}
if (!supportsMethodOf(ze)) {
ZipMethod m = ZipMethod.getMethodByCode(ze.getMethod());
if (m == null) {
throw
new UnsupportedZipFeatureException(UnsupportedZipFeatureException
.Feature.METHOD, ze);
} else {
throw new UnsupportedZipFeatureException(m, ze);
}
}
}
}