BinaryHunk.java

/*
 * Copyright (C) 2008, Google Inc.
 * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.patch;

import static org.eclipse.jgit.lib.Constants.encodeASCII;
import static org.eclipse.jgit.util.RawParseUtils.match;
import static org.eclipse.jgit.util.RawParseUtils.nextLF;
import static org.eclipse.jgit.util.RawParseUtils.parseBase10;

/**
 * Part of a "GIT binary patch" to describe the pre-image or post-image
 */
public class BinaryHunk {
    private static final byte[] LITERAL = encodeASCII("literal "); //$NON-NLS-1$

    private static final byte[] DELTA = encodeASCII("delta "); //$NON-NLS-1$

    /** Type of information stored in a binary hunk. */
    public enum Type {
        /** The full content is stored, deflated. */
        LITERAL_DEFLATED,

        /** A Git pack-style delta is stored, deflated. */
        DELTA_DEFLATED;
    }

    private final FileHeader file;

    /** Offset within {@link #file}.buf to the "literal" or "delta " line. */
    final int startOffset;

    /** Position 1 past the end of this hunk within {@link #file}'s buf. */
    int endOffset;

    /** Type of the data meaning. */
    private Type type;

    /** Inflated length of the data. */
    private int length;

    BinaryHunk(FileHeader fh, int offset) {
        file = fh;
        startOffset = offset;
    }

    /**
     * Get header for the file this hunk applies to.
     *
     * @return header for the file this hunk applies to.
     */
    public FileHeader getFileHeader() {
        return file;
    }

    /**
     * Get the byte array holding this hunk's patch script.
     *
     * @return the byte array holding this hunk's patch script.
     */
    public byte[] getBuffer() {
        return file.buf;
    }

    /**
     * Get offset the start of this hunk in {@link #getBuffer()}.
     *
     * @return offset the start of this hunk in {@link #getBuffer()}.
     */
    public int getStartOffset() {
        return startOffset;
    }

    /**
     * Get offset one past the end of the hunk in {@link #getBuffer()}.
     *
     * @return offset one past the end of the hunk in {@link #getBuffer()}.
     */
    public int getEndOffset() {
        return endOffset;
    }

    /**
     * Get type of this binary hunk.
     *
     * @return type of this binary hunk.
     */
    public Type getType() {
        return type;
    }

    /**
     * Get inflated size of this hunk's data.
     *
     * @return inflated size of this hunk's data.
     */
    public int getSize() {
        return length;
    }

    int parseHunk(int ptr, int end) {
        final byte[] buf = file.buf;

        if (match(buf, ptr, LITERAL) >= 0) {
            type = Type.LITERAL_DEFLATED;
            length = parseBase10(buf, ptr + LITERAL.length, null);

        } else if (match(buf, ptr, DELTA) >= 0) {
            type = Type.DELTA_DEFLATED;
            length = parseBase10(buf, ptr + DELTA.length, null);

        } else {
            // Not a valid binary hunk. Signal to the caller that
            // we cannot parse any further and that this line should
            // be treated otherwise.
            //
            return -1;
        }
        ptr = nextLF(buf, ptr);

        // Skip until the first blank line; that is the end of the binary
        // encoded information in this hunk. To save time we don't do a
        // validation of the binary data at this point.
        //
        while (ptr < end) {
            final boolean empty = buf[ptr] == '\n';
            ptr = nextLF(buf, ptr);
            if (empty)
                break;
        }

        return ptr;
    }
}