    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 * http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.commons.compress.archivers.ar;
    020
    021import java.io.EOFException;
    022import java.io.IOException;
    023import java.io.InputStream;
    024import java.nio.charset.StandardCharsets;
    025import java.util.Arrays;
    026import java.util.regex.Pattern;
    027
    028import org.apache.commons.compress.archivers.ArchiveInputStream;
    029import org.apache.commons.compress.utils.ArchiveUtils;
    030import org.apache.commons.compress.utils.IOUtils;
    031import org.apache.commons.compress.utils.ParsingUtils;
    032
    033/**
    034 * Implements the "ar" archive format as an input stream.
    035 *
    036 * @NotThreadSafe
    037 */
    038public class ArArchiveInputStream extends ArchiveInputStream<ArArchiveEntry> {
    039
    040    // offsets and length of meta data parts
    041    private static final int NAME_OFFSET = 0;
    042    private static final int NAME_LEN = 16;
    043    private static final int LAST_MODIFIED_OFFSET = NAME_LEN;
    044
    045    private static final int LAST_MODIFIED_LEN = 12;
    046
    047    private static final int USER_ID_OFFSET = LAST_MODIFIED_OFFSET + LAST_MODIFIED_LEN;
    048
    049    private static final int USER_ID_LEN = 6;
    050
    051    private static final int GROUP_ID_OFFSET = USER_ID_OFFSET + USER_ID_LEN;
    052    private static final int GROUP_ID_LEN = 6;
    053    private static final int FILE_MODE_OFFSET = GROUP_ID_OFFSET + GROUP_ID_LEN;
    054    private static final int FILE_MODE_LEN = 8;
    055    private static final int LENGTH_OFFSET = FILE_MODE_OFFSET + FILE_MODE_LEN;
    056    private static final int LENGTH_LEN = 10;
    057    static final String BSD_LONGNAME_PREFIX = "#1/";
    058    private static final int BSD_LONGNAME_PREFIX_LEN = BSD_LONGNAME_PREFIX.length();
    059    private static final Pattern BSD_LONGNAME_PATTERN = Pattern.compile("^" + BSD_LONGNAME_PREFIX + "\\d+");
    060    private static final String GNU_STRING_TABLE_NAME = "//";
    061    private static final Pattern GNU_LONGNAME_PATTERN = Pattern.compile("^/\\d+");
    062
    063    /**
    064     * Does the name look like it is a long name (or a name containing spaces) as encoded by BSD ar?
    065     * <p>
    066     * From the FreeBSD ar(5) man page:
    067     * </p>
    068     * <pre>
    069     * BSD   In the BSD variant, names that are shorter than 16
    070     *       characters and without embedded spaces are stored
    071     *       directly in this field.  If a name has an embedded
    072     *       space, or if it is longer than 16 characters, then
    073     *       the string "#1/" followed by the decimal represen-
    074     *       tation of the length of the file name is placed in
    075     *       this field. The actual file name is stored immedi-
    076     *       ately after the archive header.  The content of the
    077     *       archive member follows the file name.  The ar_size
    078     *       field of the header (see below) will then hold the
    079     *       sum of the size of the file name and the size of
    080     *       the member.
    081     * </pre>
    082     *
    083     * @since 1.3
    084     */
    085    private static boolean isBSDLongName(final String name) {
    086        return name != null && BSD_LONGNAME_PATTERN.matcher(name).matches();
    087    }
    088
    089    /**
    090     * Is this the name of the "Archive String Table" as used by SVR4/GNU to store long file names?
    091     * <p>
    092     * 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.
    093     * </p>
    094     * <p>
    095     * 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
    096     * section.
    097     * </p>
    098     * <p>
    099     * 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
    100     * are number of characters, not line or string number within the "//" file.
    101     * </p>
    102     */
    103    private static boolean isGNUStringTable(final String name) {
    104        return GNU_STRING_TABLE_NAME.equals(name);
    105    }
    106
    107    /**
    108     * Checks if the signature matches ASCII "!&lt;arch&gt;" followed by a single LF control character
    109     *
    110     * @param signature the bytes to check
    111     * @param length    the number of bytes to check
    112     * @return true, if this stream is an Ar archive stream, false otherwise
    113     */
    114    public static boolean matches(final byte[] signature, final int length) {
    115        // 3c21 7261 6863 0a3e
    116
    117        return length >= 8 && signature[0] == 0x21 && signature[1] == 0x3c && signature[2] == 0x61 && signature[3] == 0x72 && signature[4] == 0x63
    118                && signature[5] == 0x68 && signature[6] == 0x3e && signature[7] == 0x0a;
    119    }
    120
    121    private long offset;
    122
    123    private boolean closed;
    124
    125    /*
    126     * If getNextEntry has been called, the entry metadata is stored in currentEntry.
    127     */
    128    private ArArchiveEntry currentEntry;
    129
    130    /** Storage area for extra long names (GNU ar). */
    131    private byte[] namebuffer;
    132
    133    /**
    134     * The offset where the current entry started. -1 if no entry has been called
    135     */
    136    private long entryOffset = -1;
    137
    138    /** Cached buffer for meta data - must only be used locally in the class (COMPRESS-172 - reduce garbage collection). */
    139    private final byte[] metaData = new byte[NAME_LEN + LAST_MODIFIED_LEN + USER_ID_LEN + GROUP_ID_LEN + FILE_MODE_LEN + LENGTH_LEN];
    140
    141    /**
    142     * Constructs an Ar input stream with the referenced stream
    143     *
    144     * @param inputStream the ar input stream
    145     */
    146    public ArArchiveInputStream(final InputStream inputStream) {
    147        super(inputStream, StandardCharsets.US_ASCII.name());
    148    }
    149
    150    private int asInt(final byte[] byteArray, final int offset, final int len) throws IOException {
    151        return asInt(byteArray, offset, len, 10, false);
    152    }
    153
    154    private int asInt(final byte[] byteArray, final int offset, final int len, final boolean treatBlankAsZero) throws IOException {
    155        return asInt(byteArray, offset, len, 10, treatBlankAsZero);
    156    }
    157
    158    private int asInt(final byte[] byteArray, final int offset, final int len, final int base) throws IOException {
    159        return asInt(byteArray, offset, len, base, false);
    160    }
    161
    162    private int asInt(final byte[] byteArray, final int offset, final int len, final int base, final boolean treatBlankAsZero) throws IOException {
    163        final String string = ArchiveUtils.toAsciiString(byteArray, offset, len).trim();
    164        if (string.isEmpty() && treatBlankAsZero) {
    165            return 0;
    166        }
    167        return ParsingUtils.parseIntValue(string, base);
    168    }
    169
    170    private long asLong(final byte[] byteArray, final int offset, final int len) throws IOException {
    171        return ParsingUtils.parseLongValue(ArchiveUtils.toAsciiString(byteArray, offset, len).trim());
    172    }
    173
    174    /*
    175     * (non-Javadoc)
    176     *
    177     * @see java.io.InputStream#close()
    178     */
    179    @Override
    180    public void close() throws IOException {
    181        if (!closed) {
    182            closed = true;
    183            in.close();
    184        }
    185        currentEntry = null;
    186    }
    187
    188    /**
    189     * Reads the real name from the current stream assuming the very first bytes to be read are the real file name.
    190     *
    191     * @see #isBSDLongName
    192     *
    193     * @since 1.3
    194     */
    195    private String getBSDLongName(final String bsdLongName) throws IOException {
    196        final int nameLen = ParsingUtils.parseIntValue(bsdLongName.substring(BSD_LONGNAME_PREFIX_LEN));
    197        final byte[] name = IOUtils.readRange(in, nameLen);
    198        final int read = name.length;
    199        trackReadBytes(read);
    200        if (read != nameLen) {
    201            throw new EOFException();
    202        }
    203        return ArchiveUtils.toAsciiString(name);
    204    }
    205
    206    /**
    207     * Gets an extended name from the GNU extended name buffer.
    208     *
    209     * @param offset pointer to entry within the buffer
    210     * @return the extended file name; without trailing "/" if present.
    211     * @throws IOException if name not found or buffer not set up
    212     */
    213    private String getExtendedName(final int offset) throws IOException {
    214        if (namebuffer == null) {
    215            throw new IOException("Cannot process GNU long file name as no // record was found");
    216        }
    217        for (int i = offset; i < namebuffer.length; i++) {
    218            if (namebuffer[i] == '\012' || namebuffer[i] == 0) {
    219                // Avoid array errors
    220                if (i == 0) {
    221                    break;
    222                }
    223                if (namebuffer[i - 1] == '/') {
    224                    i--; // drop trailing /
    225                }
    226
    227                // Check there is a something to return, otherwise break out of the loop
    228                if (i - offset > 0) {
    229                    return ArchiveUtils.toAsciiString(namebuffer, offset, i - offset);
    230                }
    231                break;
    232            }
    233        }
    234        throw new IOException("Failed to read entry: " + offset);
    235    }
    236
    237    /**
    238     * Returns the next AR entry in this stream.
    239     *
    240     * @return the next AR entry.
    241     * @throws IOException if the entry could not be read
    242     * @deprecated Use {@link #getNextEntry()}.
    243     */
    244    @Deprecated
    245    public ArArchiveEntry getNextArEntry() throws IOException {
    246        if (currentEntry != null) {
    247            final long entryEnd = entryOffset + currentEntry.getLength();
    248            final long skipped = org.apache.commons.io.IOUtils.skip(in, entryEnd - offset);
    249            trackReadBytes(skipped);
    250            currentEntry = null;
    251        }
    252
    253        if (offset == 0) {
    254            final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.HEADER);
    255            final byte[] realized = IOUtils.readRange(in, expected.length);
    256            final int read = realized.length;
    257            trackReadBytes(read);
    258            if (read != expected.length) {
    259                throw new IOException("Failed to read header. Occurred at byte: " + getBytesRead());
    260            }
    261            if (!Arrays.equals(expected, realized)) {
    262                throw new IOException("Invalid header " + ArchiveUtils.toAsciiString(realized));
    263            }
    264        }
    265
    266        if (offset % 2 != 0) {
    267            if (in.read() < 0) {
    268                // hit eof
    269                return null;
    270            }
    271            trackReadBytes(1);
    272        }
    273
    274        {
    275            final int read = IOUtils.readFully(in, metaData);
    276            trackReadBytes(read);
    277            if (read == 0) {
    278                return null;
    279            }
    280            if (read < metaData.length) {
    281                throw new IOException("Truncated ar archive");
    282            }
    283        }
    284
    285        {
    286            final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.TRAILER);
    287            final byte[] realized = IOUtils.readRange(in, expected.length);
    288            final int read = realized.length;
    289            trackReadBytes(read);
    290            if (read != expected.length) {
    291                throw new IOException("Failed to read entry trailer. Occurred at byte: " + getBytesRead());
    292            }
    293            if (!Arrays.equals(expected, realized)) {
    294                throw new IOException("Invalid entry trailer. not read the content? Occurred at byte: " + getBytesRead());
    295            }
    296        }
    297
    298        entryOffset = offset;
    299
    300//        GNU ar uses a '/' to mark the end of the file name; this allows for the use of spaces without the use of an extended file name.
    301
    302        // entry name is stored as ASCII string
    303        String temp = ArchiveUtils.toAsciiString(metaData, NAME_OFFSET, NAME_LEN).trim();
    304        if (isGNUStringTable(temp)) { // GNU extended file names entry
    305            currentEntry = readGNUStringTable(metaData, LENGTH_OFFSET, LENGTH_LEN);
    306            return getNextArEntry();
    307        }
    308
    309        long len;
    310        try {
    311            len = asLong(metaData, LENGTH_OFFSET, LENGTH_LEN);
    312        } catch (final NumberFormatException ex) {
    313            throw new IOException("Broken archive, unable to parse ar_size field as a number", ex);
    314        }
    315        if (temp.endsWith("/")) { // GNU terminator
    316            temp = temp.substring(0, temp.length() - 1);
    317        } else if (isGNULongName(temp)) {
    318            final int off = ParsingUtils.parseIntValue(temp.substring(1));// get the offset
    319            temp = getExtendedName(off); // convert to the long name
    320        } else if (isBSDLongName(temp)) {
    321            temp = getBSDLongName(temp);
    322            // entry length contained the length of the file name in
    323            // addition to the real length of the entry.
    324            // assume file name was ASCII, there is no "standard" otherwise
    325            final int nameLen = temp.length();
    326            len -= nameLen;
    327            entryOffset += nameLen;
    328        }
    329
    330        if (len < 0) {
    331            throw new IOException("broken archive, entry with negative size");
    332        }
    333
    334        try {
    335            currentEntry = new ArArchiveEntry(temp, len, asInt(metaData, USER_ID_OFFSET, USER_ID_LEN, true),
    336                    asInt(metaData, GROUP_ID_OFFSET, GROUP_ID_LEN, true), asInt(metaData, FILE_MODE_OFFSET, FILE_MODE_LEN, 8),
    337                    asLong(metaData, LAST_MODIFIED_OFFSET, LAST_MODIFIED_LEN));
    338            return currentEntry;
    339        } catch (final NumberFormatException ex) {
    340            throw new IOException("Broken archive, unable to parse entry metadata fields as numbers", ex);
    341        }
    342    }
    343
    344    /*
    345     * (non-Javadoc)
    346     *
    347     * @see org.apache.commons.compress.archivers.ArchiveInputStream#getNextEntry()
    348     */
    349    @Override
    350    public ArArchiveEntry getNextEntry() throws IOException {
    351        return getNextArEntry();
    352    }
    353
    354    /**
    355     * Does the name look like it is a long name (or a name containing spaces) as encoded by SVR4/GNU ar?
    356     *
    357     * @see #isGNUStringTable
    358     */
    359    private boolean isGNULongName(final String name) {
    360        return name != null && GNU_LONGNAME_PATTERN.matcher(name).matches();
    361    }
    362
    363    /*
    364     * (non-Javadoc)
    365     *
    366     * @see java.io.InputStream#read(byte[], int, int)
    367     */
    368    @Override
    369    public int read(final byte[] b, final int off, final int len) throws IOException {
    370        if (len == 0) {
    371            return 0;
    372        }
    373        if (currentEntry == null) {
    374            throw new IllegalStateException("No current ar entry");
    375        }
    376        final long entryEnd = entryOffset + currentEntry.getLength();
    377        if (len < 0 || offset >= entryEnd) {
    378            return -1;
    379        }
    380        final int toRead = (int) Math.min(len, entryEnd - offset);
    381        final int ret = this.in.read(b, off, toRead);
    382        trackReadBytes(ret);
    383        return ret;
    384    }
    385
    386    /**
    387     * Reads the GNU archive String Table.
    388     *
    389     * @see #isGNUStringTable
    390     */
    391    private ArArchiveEntry readGNUStringTable(final byte[] length, final int offset, final int len) throws IOException {
    392        int bufflen;
    393        try {
    394            bufflen = asInt(length, offset, len); // Assume length will fit in an int
    395        } catch (final NumberFormatException ex) {
    396            throw new IOException("Broken archive, unable to parse GNU string table length field as a number", ex);
    397        }
    398
    399        namebuffer = IOUtils.readRange(in, bufflen);
    400        final int read = namebuffer.length;
    401        trackReadBytes(read);
    402        if (read != bufflen) {
    403            throw new IOException("Failed to read complete // record: expected=" + bufflen + " read=" + read);
    404        }
    405        return new ArArchiveEntry(GNU_STRING_TABLE_NAME, bufflen);
    406    }
    407
    408    private void trackReadBytes(final long read) {
    409        count(read);
    410        if (read > 0) {
    411            offset += read;
    412        }
    413    }
    414}