CommitMsgHook.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.File;
import java.io.IOException;
import java.io.PrintStream;

import org.eclipse.jgit.api.errors.AbortedByHookException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.Repository;

/**
 * The <code>commit-msg</code> hook implementation. This hook is run before the
 * commit and can reject the commit. It passes one argument to the hook script,
 * which is the path to the COMMIT_MSG file, relative to the repository
 * workTree.
 *
 * @since 4.0
 */
public class CommitMsgHook extends GitHook<String> {

    /**
     * Constant indicating the name of the commit-smg hook.
     */
    public static final String NAME = "commit-msg"; //$NON-NLS-1$

    /**
     * The commit message.
     */
    private String commitMessage;

    /**
     * Constructor for CommitMsgHook
     * <p>
     * This constructor will use the default error stream.
     * </p>
     *
     * @param repo
     *            The repository
     * @param outputStream
     *            The output stream the hook must use. {@code null} is allowed,
     *            in which case the hook will use {@code System.out}.
     */
    protected CommitMsgHook(Repository repo, PrintStream outputStream) {
        super(repo, outputStream);
    }

    /**
     * Constructor for CommitMsgHook
     *
     * @param repo
     *            The repository
     * @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}.
     * @since 5.6
     */
    protected CommitMsgHook(Repository repo, PrintStream outputStream,
            PrintStream errorStream) {
        super(repo, outputStream, errorStream);
    }

    /** {@inheritDoc} */
    @Override
    public String call() throws IOException, AbortedByHookException {
        if (commitMessage == null) {
            throw new IllegalStateException();
        }
        if (canRun()) {
            getRepository().writeCommitEditMsg(commitMessage);
            doRun();
            commitMessage = getRepository().readCommitEditMsg();
        }
        return commitMessage;
    }

    /**
     * @return {@code true} if and only if the path to the message commit file
     *         is not null (which would happen in a bare repository) and the
     *         commit message is also not null.
     */
    private boolean canRun() {
        return getCommitEditMessageFilePath() != null && commitMessage != null;
    }

    /** {@inheritDoc} */
    @Override
    public String getHookName() {
        return NAME;
    }

    /**
     * {@inheritDoc}
     *
     * This hook receives one parameter, which is the path to the file holding
     * the current commit-msg, relative to the repository's work tree.
     */
    @Override
    protected String[] getParameters() {
        return new String[] { getCommitEditMessageFilePath() };
    }

    /**
     * @return The path to the commit edit message file relative to the
     *         repository's work tree, or null if the repository is bare.
     */
    private String getCommitEditMessageFilePath() {
        File gitDir = getRepository().getDirectory();
        if (gitDir == null) {
            return null;
        }
        return Repository.stripWorkDir(getRepository().getWorkTree(), new File(
                gitDir, Constants.COMMIT_EDITMSG));
    }

    /**
     * It is mandatory to call this method with a non-null value before actually
     * calling the hook.
     *
     * @param commitMessage
     *            The commit message before the hook has run.
     * @return {@code this} for convenience.
     */
    public CommitMsgHook setCommitMessage(String commitMessage) {
        this.commitMessage = commitMessage;
        return this;
    }

}