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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.ar;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import org.apache.commons.compress.archivers.ArchiveEntry;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.utils.ArchiveUtils;
import org.apache.commons.compress.utils.IOUtils;
/**
* Implements the "ar" archive format as an input stream.
*
* @NotThreadSafe
*
*/
public class ArArchiveInputStream extends ArchiveInputStream {
private final InputStream input;
private long offset;
private boolean closed;
/*
* If getNextEntry has been called, the entry metadata is stored in
* currentEntry.
*/
private ArArchiveEntry currentEntry;
// Storage area for extra long names (GNU ar)
private byte[] namebuffer;
/*
* The offset where the current entry started. -1 if no entry has been
* called
*/
private long entryOffset = -1;
// offsets and length of meta data parts
private static final int NAME_OFFSET = 0;
private static final int NAME_LEN = 16;
private static final int LAST_MODIFIED_OFFSET = NAME_LEN;
private static final int LAST_MODIFIED_LEN = 12;
private static final int USER_ID_OFFSET = LAST_MODIFIED_OFFSET + LAST_MODIFIED_LEN;
private static final int USER_ID_LEN = 6;
private static final int GROUP_ID_OFFSET = USER_ID_OFFSET + USER_ID_LEN;
private static final int GROUP_ID_LEN = 6;
private static final int FILE_MODE_OFFSET = GROUP_ID_OFFSET + GROUP_ID_LEN;
private static final int FILE_MODE_LEN = 8;
private static final int LENGTH_OFFSET = FILE_MODE_OFFSET + FILE_MODE_LEN;
private static final int LENGTH_LEN = 10;
// cached buffer for meta data - must only be used locally in the class (COMPRESS-172 - reduce garbage collection)
private final byte[] metaData =
new byte[NAME_LEN + LAST_MODIFIED_LEN + USER_ID_LEN + GROUP_ID_LEN + FILE_MODE_LEN + LENGTH_LEN];
/**
* Constructs an Ar input stream with the referenced stream
*
* @param pInput
* the ar input stream
*/
public ArArchiveInputStream(final InputStream pInput) {
input = pInput;
closed = false;
}
/**
* Returns the next AR entry in this stream.
*
* @return the next AR entry.
* @throws IOException
* if the entry could not be read
*/
public ArArchiveEntry getNextArEntry() throws IOException {
if (currentEntry != null) {
final long entryEnd = entryOffset + currentEntry.getLength();
final long skipped = IOUtils.skip(input, entryEnd - offset);
trackReadBytes(skipped);
currentEntry = null;
}
if (offset == 0) {
final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.HEADER);
final byte[] realized = IOUtils.readRange(input, expected.length);
final int read = realized.length;
trackReadBytes(read);
if (read != expected.length) {
throw new IOException("Failed to read header. Occurred at byte: " + getBytesRead());
}
if (!Arrays.equals(expected, realized)) {
throw new IOException("Invalid header " + ArchiveUtils.toAsciiString(realized));
}
}
if (offset % 2 != 0) {
if (input.read() < 0) {
// hit eof
return null;
}
trackReadBytes(1);
}
{
final int read = IOUtils.readFully(input, metaData);
trackReadBytes(read);
if (read == 0) {
return null;
}
if (read < metaData.length) {
throw new IOException("Truncated ar archive");
}
}
{
final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.TRAILER);
final byte[] realized = IOUtils.readRange(input, expected.length);
final int read = realized.length;
trackReadBytes(read);
if (read != expected.length) {
throw new IOException("Failed to read entry trailer. Occurred at byte: " + getBytesRead());
}
if (!Arrays.equals(expected, realized)) {
throw new IOException("Invalid entry trailer. not read the content? Occurred at byte: " + getBytesRead());
}
}
entryOffset = offset;
// GNU ar uses a '/' to mark the end of the filename; this allows for the use of spaces without the use of an extended filename.
// entry name is stored as ASCII string
String temp = ArchiveUtils.toAsciiString(metaData, NAME_OFFSET, NAME_LEN).trim();
if (isGNUStringTable(temp)) { // GNU extended filenames entry
currentEntry = readGNUStringTable(metaData, LENGTH_OFFSET, LENGTH_LEN);
return getNextArEntry();
}
long len = asLong(metaData, LENGTH_OFFSET, LENGTH_LEN);
if (temp.endsWith("/")) { // GNU terminator
temp = temp.substring(0, temp.length() - 1);
} else if (isGNULongName(temp)) {
final int off = Integer.parseInt(temp.substring(1));// get the offset
temp = getExtendedName(off); // convert to the long name
} else if (isBSDLongName(temp)) {
temp = getBSDLongName(temp);
// entry length contained the length of the file name in
// addition to the real length of the entry.
// assume file name was ASCII, there is no "standard" otherwise
final int nameLen = temp.length();
len -= nameLen;
entryOffset += nameLen;
}
if (len < 0) {
throw new IOException("broken archive, entry with negative size");
}
currentEntry = new ArArchiveEntry(temp, len,
asInt(metaData, USER_ID_OFFSET, USER_ID_LEN, true),
asInt(metaData, GROUP_ID_OFFSET, GROUP_ID_LEN, true),
asInt(metaData, FILE_MODE_OFFSET, FILE_MODE_LEN, 8),
asLong(metaData, LAST_MODIFIED_OFFSET, LAST_MODIFIED_LEN));
return currentEntry;
}
/**
* Get an extended name from the GNU extended name buffer.
*
* @param offset pointer to entry within the buffer
* @return the extended file name; without trailing "/" if present.
* @throws IOException if name not found or buffer not set up
*/
private String getExtendedName(final int offset) throws IOException {
if (namebuffer == null) {
throw new IOException("Cannot process GNU long filename as no // record was found");
}
for (int i = offset; i < namebuffer.length; i++) {
if (namebuffer[i] == '\012' || namebuffer[i] == 0) {
if (namebuffer[i - 1] == '/') {
i--; // drop trailing /
}
return ArchiveUtils.toAsciiString(namebuffer, offset, i - offset);
}
}
throw new IOException("Failed to read entry: " + offset);
}
private long asLong(final byte[] byteArray, final int offset, final int len) {
return Long.parseLong(ArchiveUtils.toAsciiString(byteArray, offset, len).trim());
}
private int asInt(final byte[] byteArray, final int offset, final int len) {
return asInt(byteArray, offset, len, 10, false);
}
private int asInt(final byte[] byteArray, final int offset, final int len, final boolean treatBlankAsZero) {
return asInt(byteArray, offset, len, 10, treatBlankAsZero);
}
private int asInt(final byte[] byteArray, final int offset, final int len, final int base) {
return asInt(byteArray, offset, len, base, false);
}
private int asInt(final byte[] byteArray, final int offset, final int len, final int base, final boolean treatBlankAsZero) {
final String string = ArchiveUtils.toAsciiString(byteArray, offset, len).trim();
if (string.isEmpty() && treatBlankAsZero) {
return 0;
}
return Integer.parseInt(string, base);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.commons.compress.archivers.ArchiveInputStream#getNextEntry()
*/
@Override
public ArchiveEntry getNextEntry() throws IOException {
return getNextArEntry();
}
/*
* (non-Javadoc)
*
* @see java.io.InputStream#close()
*/
@Override
public void close() throws IOException {
if (!closed) {
closed = true;
input.close();
}
currentEntry = null;
}
/*
* (non-Javadoc)
*
* @see java.io.InputStream#read(byte[], int, int)
*/
@Override
public int read(final byte[] b, final int off, final int len) throws IOException {
if (len == 0) {
return 0;
}
if (currentEntry == null) {
throw new IllegalStateException("No current ar entry");
}
final long entryEnd = entryOffset + currentEntry.getLength();
if (len < 0 || offset >= entryEnd) {
return -1;
}
final int toRead = (int) Math.min(len, entryEnd - offset);
final int ret = this.input.read(b, off, toRead);
trackReadBytes(ret);
return ret;
}
/**
* Checks if the signature matches ASCII "!<arch>" followed by a single LF
* control character
*
* @param signature
* the bytes to check
* @param length
* the number of bytes to check
* @return true, if this stream is an Ar archive stream, false otherwise
*/
public static boolean matches(final byte[] signature, final int length) {
// 3c21 7261 6863 0a3e
return length >= 8 && signature[0] == 0x21 &&
signature[1] == 0x3c && signature[2] == 0x61 &&
signature[3] == 0x72 && signature[4] == 0x63 &&
signature[5] == 0x68 && signature[6] == 0x3e &&
signature[7] == 0x0a;
}
static final String BSD_LONGNAME_PREFIX = "#1/";
private static final int BSD_LONGNAME_PREFIX_LEN =
BSD_LONGNAME_PREFIX.length();
private static final String BSD_LONGNAME_PATTERN =
"^" + BSD_LONGNAME_PREFIX + "\\d+";
/**
* Does the name look like it is a long name (or a name containing
* spaces) as encoded by BSD ar?
*
* From the FreeBSD ar(5) man page:
*
* BSD In the BSD variant, names that are shorter than 16
* characters and without embedded spaces are stored
* directly in this field. If a name has an embedded
* space, or if it is longer than 16 characters, then
* the string "#1/" followed by the decimal represen-
* tation of the length of the file name is placed in
* this field. The actual file name is stored immedi-
* ately after the archive header. The content of the
* archive member follows the file name. The ar_size
* field of the header (see below) will then hold the
* sum of the size of the file name and the size of
* the member.
*
*
* @since 1.3
*/
private static boolean isBSDLongName(final String name) {
return name != null && name.matches(BSD_LONGNAME_PATTERN);
}
/**
* Reads the real name from the current stream assuming the very
* first bytes to be read are the real file name.
*
* @see #isBSDLongName
*
* @since 1.3
*/
private String getBSDLongName(final String bsdLongName) throws IOException {
final int nameLen =
Integer.parseInt(bsdLongName.substring(BSD_LONGNAME_PREFIX_LEN));
final byte[] name = IOUtils.readRange(input, nameLen);
final int read = name.length;
trackReadBytes(read);
if (read != nameLen) {
throw new EOFException();
}
return ArchiveUtils.toAsciiString(name);
}
private static final String GNU_STRING_TABLE_NAME = "//";
/**
* Is this the name of the "Archive String Table" as used by
* SVR4/GNU to store long file names?
*
* GNU ar stores multiple extended file names in the data section
* of a file with the name "//", this record is referred to by
* future headers.
*
* A header references an extended file name by storing a "/"
* followed by a decimal offset to the start of the file name in
* the extended file name data section.
*
* The format of the "//" file itself is simply a list of the
* long file names, each separated by one or more LF
* characters. Note that the decimal offsets are number of
* characters, not line or string number within the "//" file.
*/
private static boolean isGNUStringTable(final String name) {
return GNU_STRING_TABLE_NAME.equals(name);
}
private void trackReadBytes(final long read) {
count(read);
if (read > 0) {
offset += read;
}
}
/**
* Reads the GNU archive String Table.
*
* @see #isGNUStringTable
*/
private ArArchiveEntry readGNUStringTable(final byte[] length, final int offset, final int len) throws IOException {
final int bufflen = asInt(length, offset, len); // Assume length will fit in an int
namebuffer = IOUtils.readRange(input, bufflen);
final int read = namebuffer.length;
trackReadBytes(read);
if (read != bufflen){
throw new IOException("Failed to read complete // record: expected="
+ bufflen + " read=" + read);
}
return new ArArchiveEntry(GNU_STRING_TABLE_NAME, bufflen);
}
private static final String GNU_LONGNAME_PATTERN = "^/\\d+";
/**
* Does the name look like it is a long name (or a name containing
* spaces) as encoded by SVR4/GNU ar?
*
* @see #isGNUStringTable
*/
private boolean isGNULongName(final String name) {
return name != null && name.matches(GNU_LONGNAME_PATTERN);
}
}