WalkPushConnection.java

/*
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> 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.transport;

import static org.eclipse.jgit.transport.WalkRemoteObjectDatabase.ROOT_DIR;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

import org.eclipse.jgit.errors.TransportException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.internal.storage.file.PackFile;
import org.eclipse.jgit.internal.storage.pack.PackExt;
import org.eclipse.jgit.internal.storage.pack.PackWriter;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectIdRef;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Ref.Storage;
import org.eclipse.jgit.lib.RefWriter;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.transport.RemoteRefUpdate.Status;

/**
 * Generic push support for dumb transport protocols.
 * <p>
 * Since there are no Git-specific smarts on the remote side of the connection
 * the client side must handle everything on its own. The generic push support
 * requires being able to delete, create and overwrite files on the remote side,
 * as well as create any missing directories (if necessary). Typically this can
 * be handled through an FTP style protocol.
 * <p>
 * Objects not on the remote side are uploaded as pack files, using one pack
 * file per invocation. This simplifies the implementation as only two data
 * files need to be written to the remote repository.
 * <p>
 * Push support supplied by this class is not multiuser safe. Concurrent pushes
 * to the same repository may yield an inconsistent reference database which may
 * confuse fetch clients.
 * <p>
 * A single push is concurrently safe with multiple fetch requests, due to the
 * careful order of operations used to update the repository. Clients fetching
 * may receive transient failures due to short reads on certain files if the
 * protocol does not support atomic file replacement.
 *
 * @see WalkRemoteObjectDatabase
 */
class WalkPushConnection extends BaseConnection implements PushConnection {
    /** The repository this transport pushes out of. */
    private final Repository local;

    /** Location of the remote repository we are writing to. */
    private final URIish uri;

    /** Database connection to the remote repository. */
    final WalkRemoteObjectDatabase dest;

    /** The configured transport we were constructed by. */
    private final Transport transport;

    /**
     * Packs already known to reside in the remote repository.
     * <p>
     * This is a LinkedHashMap to maintain the original order.
     */
    private LinkedHashMap<String, String> packNames;

    /** Complete listing of refs the remote will have after our push. */
    private Map<String, Ref> newRefs;

    /**
     * Updates which require altering the packed-refs file to complete.
     * <p>
     * If this collection is non-empty then any refs listed in {@link #newRefs}
     * with a storage class of {@link Storage#PACKED} will be written.
     */
    private Collection<RemoteRefUpdate> packedRefUpdates;

    WalkPushConnection(final WalkTransport walkTransport,
            final WalkRemoteObjectDatabase w) {
        transport = (Transport) walkTransport;
        local = transport.local;
        uri = transport.getURI();
        dest = w;
    }

    /** {@inheritDoc} */
    @Override
    public void push(final ProgressMonitor monitor,
            final Map<String, RemoteRefUpdate> refUpdates)
            throws TransportException {
        push(monitor, refUpdates, null);
    }

    /** {@inheritDoc} */
    @Override
    public void push(final ProgressMonitor monitor,
            final Map<String, RemoteRefUpdate> refUpdates, OutputStream out)
            throws TransportException {
        markStartedOperation();
        packNames = null;
        newRefs = new TreeMap<>(getRefsMap());
        packedRefUpdates = new ArrayList<>(refUpdates.size());

        // Filter the commands and issue all deletes first. This way we
        // can correctly handle a directory being cleared out and a new
        // ref using the directory name being created.
        //
        final List<RemoteRefUpdate> updates = new ArrayList<>();
        for (RemoteRefUpdate u : refUpdates.values()) {
            final String n = u.getRemoteName();
            if (!n.startsWith("refs/") || !Repository.isValidRefName(n)) { //$NON-NLS-1$
                u.setStatus(Status.REJECTED_OTHER_REASON);
                u.setMessage(JGitText.get().funnyRefname);
                continue;
            }

            if (AnyObjectId.isEqual(ObjectId.zeroId(), u.getNewObjectId()))
                deleteCommand(u);
            else
                updates.add(u);
        }

        // If we have any updates we need to upload the objects first, to
        // prevent creating refs pointing at non-existent data. Then we
        // can update the refs, and the info-refs file for dumb transports.
        //
        if (!updates.isEmpty())
            sendpack(updates, monitor);
        for (RemoteRefUpdate u : updates)
            updateCommand(u);

        // Is this a new repository? If so we should create additional
        // metadata files so it is properly initialized during the push.
        //
        if (!updates.isEmpty() && isNewRepository())
            createNewRepository(updates);

        RefWriter refWriter = new RefWriter(newRefs.values()) {
            @Override
            protected void writeFile(String file, byte[] content)
                    throws IOException {
                dest.writeFile(ROOT_DIR + file, content);
            }
        };
        if (!packedRefUpdates.isEmpty()) {
            try {
                refWriter.writePackedRefs();
                for (RemoteRefUpdate u : packedRefUpdates)
                    u.setStatus(Status.OK);
            } catch (IOException err) {
                for (RemoteRefUpdate u : packedRefUpdates) {
                    u.setStatus(Status.REJECTED_OTHER_REASON);
                    u.setMessage(err.getMessage());
                }
                throw new TransportException(uri, JGitText.get().failedUpdatingRefs, err);
            }
        }

        try {
            refWriter.writeInfoRefs();
        } catch (IOException err) {
            throw new TransportException(uri, JGitText.get().failedUpdatingRefs, err);
        }
    }

    /** {@inheritDoc} */
    @Override
    public void close() {
        dest.close();
    }

    private void sendpack(final List<RemoteRefUpdate> updates,
            final ProgressMonitor monitor) throws TransportException {
        PackFile pack = null;
        PackFile idx = null;
        try (PackWriter writer = new PackWriter(transport.getPackConfig(),
                local.newObjectReader())) {

            final Set<ObjectId> need = new HashSet<>();
            final Set<ObjectId> have = new HashSet<>();
            for (RemoteRefUpdate r : updates)
                need.add(r.getNewObjectId());
            for (Ref r : getRefs()) {
                have.add(r.getObjectId());
                if (r.getPeeledObjectId() != null)
                    have.add(r.getPeeledObjectId());
            }
            writer.preparePack(monitor, need, have);

            // We don't have to continue further if the pack will
            // be an empty pack, as the remote has all objects it
            // needs to complete this change.
            //
            if (writer.getObjectCount() == 0)
                return;

            packNames = new LinkedHashMap<>();
            for (String n : dest.getPackNames())
                packNames.put(n, n);

            File packDir = new File("pack"); //$NON-NLS-1$
            pack = new PackFile(packDir, writer.computeName(),
                    PackExt.PACK);
            idx = pack.create(PackExt.INDEX);

            if (packNames.remove(pack.getName()) != null) {
                // The remote already contains this pack. We should
                // remove the index before overwriting to prevent bad
                // offsets from appearing to clients.
                //
                dest.writeInfoPacks(packNames.keySet());
                dest.deleteFile(idx.getPath());
            }

            // Write the pack file, then the index, as readers look the
            // other direction (index, then pack file).
            //
            String wt = "Put " + pack.getName().substring(0, 12); //$NON-NLS-1$
            try (OutputStream os = new BufferedOutputStream(
                    dest.writeFile(pack.getPath(), monitor,
                            wt + "." + pack.getPackExt().getExtension()))) { //$NON-NLS-1$
                writer.writePack(monitor, monitor, os);
            }

            try (OutputStream os = new BufferedOutputStream(
                    dest.writeFile(idx.getPath(), monitor,
                            wt + "." + idx.getPackExt().getExtension()))) { //$NON-NLS-1$
                writer.writeIndex(os);
            }

            // Record the pack at the start of the pack info list. This
            // way clients are likely to consult the newest pack first,
            // and discover the most recent objects there.
            //
            final ArrayList<String> infoPacks = new ArrayList<>();
            infoPacks.add(pack.getName());
            infoPacks.addAll(packNames.keySet());
            dest.writeInfoPacks(infoPacks);

        } catch (IOException err) {
            safeDelete(idx);
            safeDelete(pack);

            throw new TransportException(uri, JGitText.get().cannotStoreObjects, err);
        }
    }

    private void safeDelete(File path) {
        if (path != null) {
            try {
                dest.deleteFile(path.getPath());
            } catch (IOException cleanupFailure) {
                // Ignore the deletion failure. We probably are
                // already failing and were just trying to pick
                // up after ourselves.
            }
        }
    }

    private void deleteCommand(RemoteRefUpdate u) {
        final Ref r = newRefs.remove(u.getRemoteName());
        if (r == null) {
            // Already gone.
            //
            u.setStatus(Status.OK);
            return;
        }

        if (r.getStorage().isPacked())
            packedRefUpdates.add(u);

        if (r.getStorage().isLoose()) {
            try {
                dest.deleteRef(u.getRemoteName());
                u.setStatus(Status.OK);
            } catch (IOException e) {
                u.setStatus(Status.REJECTED_OTHER_REASON);
                u.setMessage(e.getMessage());
            }
        }

        try {
            dest.deleteRefLog(u.getRemoteName());
        } catch (IOException e) {
            u.setStatus(Status.REJECTED_OTHER_REASON);
            u.setMessage(e.getMessage());
        }
    }

    private void updateCommand(RemoteRefUpdate u) {
        try {
            dest.writeRef(u.getRemoteName(), u.getNewObjectId());
            newRefs.put(u.getRemoteName(), new ObjectIdRef.Unpeeled(
                    Storage.LOOSE, u.getRemoteName(), u.getNewObjectId()));
            u.setStatus(Status.OK);
        } catch (IOException e) {
            u.setStatus(Status.REJECTED_OTHER_REASON);
            u.setMessage(e.getMessage());
        }
    }

    private boolean isNewRepository() {
        return getRefsMap().isEmpty() && packNames != null
                && packNames.isEmpty();
    }

    private void createNewRepository(List<RemoteRefUpdate> updates)
            throws TransportException {
        try {
            final String ref = "ref: " + pickHEAD(updates) + "\n"; //$NON-NLS-1$ //$NON-NLS-2$
            final byte[] bytes = Constants.encode(ref);
            dest.writeFile(ROOT_DIR + Constants.HEAD, bytes);
        } catch (IOException e) {
            throw new TransportException(uri, JGitText.get().cannotCreateHEAD, e);
        }

        try {
            final String config = "[core]\n" //$NON-NLS-1$
                    + "\trepositoryformatversion = 0\n"; //$NON-NLS-1$
            final byte[] bytes = Constants.encode(config);
            dest.writeFile(ROOT_DIR + Constants.CONFIG, bytes);
        } catch (IOException e) {
            throw new TransportException(uri, JGitText.get().cannotCreateConfig, e);
        }
    }

    private static String pickHEAD(List<RemoteRefUpdate> updates) {
        // Try to use master if the user is pushing that, it is the
        // default branch and is likely what they want to remain as
        // the default on the new remote.
        //
        for (RemoteRefUpdate u : updates) {
            final String n = u.getRemoteName();
            if (n.equals(Constants.R_HEADS + Constants.MASTER))
                return n;
        }

        // Pick any branch, under the assumption the user pushed only
        // one to the remote side.
        //
        for (RemoteRefUpdate u : updates) {
            final String n = u.getRemoteName();
            if (n.startsWith(Constants.R_HEADS))
                return n;
        }
        return updates.get(0).getRemoteName();
    }
}