BlobBasedConfig.java

/*
 * Copyright (C) 2009, Constantine Plotnikov <constantine.plotnikov@gmail.com>
 * Copyright (C) 2009, Google Inc.
 * Copyright (C) 2009, JetBrains s.r.o. 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.lib;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.MessageFormat;

import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.util.RawParseUtils;

/**
 * Configuration file based on the blobs stored in the repository.
 *
 * This implementation currently only provides reading support, and is primarily
 * useful for supporting the {@code .gitmodules} file.
 */
public class BlobBasedConfig extends Config {
    /**
     * Parse a configuration from a byte array.
     *
     * @param base
     *            the base configuration file
     * @param blob
     *            the byte array, should be UTF-8 encoded text.
     * @throws org.eclipse.jgit.errors.ConfigInvalidException
     *             the byte array is not a valid configuration format.
     */
    public BlobBasedConfig(Config base, byte[] blob)
            throws ConfigInvalidException {
        super(base);
        final String decoded;
        if (isUtf8(blob)) {
            decoded = RawParseUtils.decode(UTF_8, blob, 3, blob.length);
        } else {
            decoded = RawParseUtils.decode(blob);
        }
        fromText(decoded);
    }

    /**
     * Load a configuration file from a blob.
     *
     * @param base
     *            the base configuration file
     * @param db
     *            the repository
     * @param objectId
     *            the object identifier
     * @throws java.io.IOException
     *             the blob cannot be read from the repository.
     * @throws org.eclipse.jgit.errors.ConfigInvalidException
     *             the blob is not a valid configuration format.
     */
    public BlobBasedConfig(Config base, Repository db, AnyObjectId objectId)
            throws IOException, ConfigInvalidException {
        this(base, read(db, objectId));
    }

    private static byte[] read(Repository db, AnyObjectId blobId)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        try (ObjectReader or = db.newObjectReader()) {
            return read(or, blobId);
        }
    }

    private static byte[] read(ObjectReader or, AnyObjectId blobId)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        ObjectLoader loader = or.open(blobId, Constants.OBJ_BLOB);
        return loader.getCachedBytes(Integer.MAX_VALUE);
    }

    /**
     * Load a configuration file from a blob stored in a specific commit.
     *
     * @param base
     *            the base configuration file
     * @param db
     *            the repository containing the objects.
     * @param treeish
     *            the tree (or commit) that contains the object
     * @param path
     *            the path within the tree
     * @throws java.io.FileNotFoundException
     *             the path does not exist in the commit's tree.
     * @throws java.io.IOException
     *             the tree and/or blob cannot be accessed.
     * @throws org.eclipse.jgit.errors.ConfigInvalidException
     *             the blob is not a valid configuration format.
     */
    public BlobBasedConfig(Config base, Repository db, AnyObjectId treeish,
            String path) throws FileNotFoundException, IOException,
            ConfigInvalidException {
        this(base, read(db, treeish, path));
    }

    private static byte[] read(Repository db, AnyObjectId treeish, String path)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        try (ObjectReader or = db.newObjectReader()) {
            TreeWalk tree = TreeWalk.forPath(or, path, asTree(or, treeish));
            if (tree == null)
                throw new FileNotFoundException(MessageFormat.format(JGitText
                        .get().entryNotFoundByPath, path));
            return read(or, tree.getObjectId(0));
        }
    }

    private static AnyObjectId asTree(ObjectReader or, AnyObjectId treeish)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        if (treeish instanceof RevTree)
            return treeish;

        if (treeish instanceof RevCommit
                && ((RevCommit) treeish).getTree() != null)
            return ((RevCommit) treeish).getTree();

        try (RevWalk rw = new RevWalk(or)) {
            return rw.parseTree(treeish).getId();
        }
    }
}