GitHook.java

/*
 * Copyright (C) 2015 Obeo. 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.hooks;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.Callable;

import org.eclipse.jgit.api.errors.AbortedByHookException;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.util.FS;
import org.eclipse.jgit.util.ProcessResult;
import org.eclipse.jgit.util.SystemReader;
import org.eclipse.jgit.util.io.TeeOutputStream;

/**
 * Git can fire off custom scripts when certain important actions occur. These
 * custom scripts are called "hooks". There are two groups of hooks: client-side
 * (that run on local operations such as committing and merging), and
 * server-side (that run on network operations such as receiving pushed
 * commits). This is the abstract super-class of the different hook
 * implementations in JGit.
 *
 * @param <T>
 *            the return type which is expected from {@link #call()}
 * @see <a href="http://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks">Git
 *      Hooks on the git-scm official site</a>
 * @since 5.11
 */
public abstract class GitHook<T> implements Callable<T> {

    private final Repository repo;

    /**
     * The output stream to be used by the hook.
     */
    private final OutputStream outputStream;

    /**
     * The error stream to be used by the hook.
     */
    private final OutputStream errorStream;

    /**
     * Constructor for GitHook.
     * <p>
     * This constructor will use stderr for the error stream.
     * </p>
     *
     * @param repo
     *            a {@link org.eclipse.jgit.lib.Repository} object.
     * @param outputStream
     *            The output stream the hook must use. {@code null} is allowed,
     *            in which case the hook will use {@code System.out}.
     */
    protected GitHook(Repository repo, OutputStream outputStream) {
        this(repo, outputStream, null);
    }

    /**
     * Constructor for GitHook
     *
     * @param repo
     *            a {@link org.eclipse.jgit.lib.Repository} object.
     * @param outputStream
     *            The output stream the hook must use. {@code null} is allowed,
     *            in which case the hook will use {@code System.out}.
     * @param errorStream
     *            The error stream the hook must use. {@code null} is allowed,
     *            in which case the hook will use {@code System.err}.
     */
    protected GitHook(Repository repo, OutputStream outputStream,
            OutputStream errorStream) {
        this.repo = repo;
        this.outputStream = outputStream;
        this.errorStream = errorStream;
    }

    /**
     * {@inheritDoc}
     * <p>
     * Run the hook.
     */
    @Override
    public abstract T call() throws IOException, AbortedByHookException;

    /**
     * Get name of the hook
     *
     * @return The name of the hook, which must not be {@code null}.
     */
    public abstract String getHookName();

    /**
     * Get the repository
     *
     * @return The repository.
     */
    protected Repository getRepository() {
        return repo;
    }

    /**
     * Override this method when needed to provide relevant parameters to the
     * underlying hook script. The default implementation returns an empty
     * array.
     *
     * @return The parameters the hook receives.
     */
    protected String[] getParameters() {
        return new String[0];
    }

    /**
     * Override to provide relevant arguments via stdin to the underlying hook
     * script. The default implementation returns {@code null}.
     *
     * @return The parameters the hook receives.
     */
    protected String getStdinArgs() {
        return null;
    }

    /**
     * Get output stream
     *
     * @return The output stream the hook must use. Never {@code null},
     *         {@code System.out} is returned by default.
     */
    protected OutputStream getOutputStream() {
        return outputStream == null ? System.out : outputStream;
    }

    /**
     * Get error stream
     *
     * @return The error stream the hook must use. Never {@code null},
     *         {@code System.err} is returned by default.
     */
    protected OutputStream getErrorStream() {
        return errorStream == null ? System.err : errorStream;
    }

    /**
     * Runs the hook, without performing any validity checks.
     *
     * @throws org.eclipse.jgit.api.errors.AbortedByHookException
     *             If the underlying hook script exited with non-zero.
     * @throws IOException
     *             if an IO error occurred
     */
    protected void doRun() throws AbortedByHookException, IOException {
        final ByteArrayOutputStream errorByteArray = new ByteArrayOutputStream();
        final TeeOutputStream stderrStream = new TeeOutputStream(errorByteArray,
                getErrorStream());
        Repository repository = getRepository();
        FS fs = repository.getFS();
        if (fs == null) {
            fs = FS.DETECTED;
        }
        ProcessResult result = fs.runHookIfPresent(repository, getHookName(),
                getParameters(), getOutputStream(), stderrStream,
                getStdinArgs());
        if (result.isExecutedWithError()) {
            handleError(new String(errorByteArray.toByteArray(),
                    SystemReader.getInstance().getDefaultCharset().name()),
                    result);
        }
    }

    /**
     * Process that the hook exited with an error. This default implementation
     * throws an {@link AbortedByHookException }. Hooks which need a different
     * behavior can overwrite this method.
     *
     * @param message
     *            error message
     * @param result
     *            The process result of the hook
     * @throws AbortedByHookException
     *             When the hook should be aborted
     * @since 5.11
     */
    protected void handleError(String message,
            final ProcessResult result)
            throws AbortedByHookException {
        throw new AbortedByHookException(message, getHookName(),
                result.getExitCode());
    }

    /**
     * Check whether a 'native' (i.e. script) hook is installed in the
     * repository.
     *
     * @return whether a native hook script is installed in the repository.
     * @since 4.11
     */
    public boolean isNativeHookPresent() {
        FS fs = getRepository().getFS();
        if (fs == null) {
            fs = FS.DETECTED;
        }
        return fs.findHook(getRepository(), getHookName()) != null;
    }

}