FileLfsServlet.java

/*
 * Copyright (C) 2015, Matthias Sohn <matthias.sohn@sap.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.lfs.server.fs;

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

import javax.servlet.AsyncContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.HttpStatus;
import org.eclipse.jgit.lfs.errors.InvalidLongObjectIdException;
import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
import org.eclipse.jgit.lfs.lib.Constants;
import org.eclipse.jgit.lfs.lib.LongObjectId;
import org.eclipse.jgit.lfs.server.internal.LfsGson;
import org.eclipse.jgit.lfs.server.internal.LfsServerText;

/**
 * Servlet supporting upload and download of large objects as defined by the
 * GitHub Large File Storage extension API extending git to allow separate
 * storage of large files
 * (https://github.com/github/git-lfs/tree/master/docs/api).
 *
 * @since 4.3
 */
@WebServlet(asyncSupported = true)
public class FileLfsServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    private final FileLfsRepository repository;

    private final long timeout;

    /**
     * <p>Constructor for FileLfsServlet.</p>
     *
     * @param repository
     *            the repository storing the large objects
     * @param timeout
     *            timeout for object upload / download in milliseconds
     */
    public FileLfsServlet(FileLfsRepository repository, long timeout) {
        this.repository = repository;
        this.timeout = timeout;
    }

    /**
     * {@inheritDoc}
     *
     * Handle object downloads
     */
    @Override
    protected void doGet(HttpServletRequest req,
            HttpServletResponse rsp) throws ServletException, IOException {
        AnyLongObjectId obj = getObjectToTransfer(req, rsp);
        if (obj != null) {
            if (repository.getSize(obj) == -1) {
                sendError(rsp, HttpStatus.SC_NOT_FOUND, MessageFormat
                        .format(LfsServerText.get().objectNotFound,
                                obj.getName()));
                return;
            }
            AsyncContext context = req.startAsync();
            context.setTimeout(timeout);
            rsp.getOutputStream()
                    .setWriteListener(new ObjectDownloadListener(repository,
                            context, rsp, obj));
        }
    }

    /**
     * Retrieve object id from request
     *
     * @param req
     *            servlet request
     * @param rsp
     *            servlet response
     * @return object id, or <code>null</code> if the object id could not be
     *         retrieved
     * @throws java.io.IOException
     *             if an I/O error occurs
     * @since 4.6
     */
    protected AnyLongObjectId getObjectToTransfer(HttpServletRequest req,
            HttpServletResponse rsp) throws IOException {
        String info = req.getPathInfo();
        int length = 1 + Constants.LONG_OBJECT_ID_STRING_LENGTH;
        if (info.length() != length) {
            sendError(rsp, HttpStatus.SC_UNPROCESSABLE_ENTITY, MessageFormat
                    .format(LfsServerText.get().invalidPathInfo, info));
            return null;
        }
        try {
            return LongObjectId.fromString(info.substring(1, length));
        } catch (InvalidLongObjectIdException e) {
            sendError(rsp, HttpStatus.SC_UNPROCESSABLE_ENTITY, e.getMessage());
            return null;
        }
    }

    /**
     * {@inheritDoc}
     *
     * Handle object uploads
     */
    @Override
    protected void doPut(HttpServletRequest req,
            HttpServletResponse rsp) throws ServletException, IOException {
        AnyLongObjectId id = getObjectToTransfer(req, rsp);
        if (id != null) {
            AsyncContext context = req.startAsync();
            context.setTimeout(timeout);
            req.getInputStream().setReadListener(new ObjectUploadListener(
                    repository, context, req, rsp, id));
        }
    }

    /**
     * Send an error response.
     *
     * @param rsp
     *            the servlet response
     * @param status
     *            HTTP status code
     * @param message
     *            error message
     * @throws java.io.IOException
     *             on failure to send the response
     * @since 4.6
     */
    protected static void sendError(HttpServletResponse rsp, int status, String message)
            throws IOException {
        if (rsp.isCommitted()) {
            rsp.getOutputStream().close();
            return;
        }
        rsp.reset();
        rsp.setStatus(status);
        try (PrintWriter writer = rsp.getWriter()) {
            LfsGson.toJson(message, writer);
            writer.flush();
        }
        rsp.flushBuffer();
    }
}