001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks;
021
022import java.io.File;
023import java.io.IOException;
024import java.io.RandomAccessFile;
025import java.util.Locale;
026
027import com.puppycrawl.tools.checkstyle.StatelessCheck;
028import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
029import com.puppycrawl.tools.checkstyle.api.FileText;
030
031/**
032 * <div>
033 * Checks whether files end with a line separator.
034 * </div>
035 *
036 * <p>
037 * Rationale: Any source files and text files in general should end with a line
038 * separator to let other easily add new content at the end of file and "diff"
039 * command does not show previous lines as changed.
040 * </p>
041 *
042 * <p>
043 * Example (the line with 'No newline at end of file' should not be in the diff):
044 * </p>
045 * <pre>
046 * &#64;&#64; -32,4 +32,5 &#64;&#64; ForbidWildcardAsReturnTypeCheck.returnTypeClassNamesIgnoreRegex
047 * PublicReferenceToPrivateTypeCheck.name = Public Reference To Private Type
048 *
049 * StaticMethodCandidateCheck.name = Static Method Candidate
050 * -StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
051 * \ No newline at end of file
052 * +StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
053 * +StaticMethodCandidateCheck.skippedMethods = Method names to skip during the check.
054 * </pre>
055 *
056 * <p>
057 * It can also trick the VCS to report the wrong owner for such lines.
058 * An engineer who has added nothing but a newline character becomes the last
059 * known author for the entire line. As a result, a mate can ask him a question
060 * to which he will not give the correct answer.
061 * </p>
062 *
063 * <p>
064 * Old Rationale: CVS source control management systems will even print
065 * a warning when it encounters a file that doesn't end with a line separator.
066 * </p>
067 *
068 * <p>
069 * Attention: property fileExtensions works with files that are passed by similar
070 * property for at <a href="https://checkstyle.org/config.html#Checker">Checker</a>.
071 * Please make sure required file extensions are mentioned at Checker's fileExtensions property.
072 * </p>
073 *
074 * <p>
075 * This will check against the platform-specific default line separator.
076 * </p>
077 *
078 * <p>
079 * It is also possible to enforce the use of a specific line-separator across
080 * platforms, with the {@code lineSeparator} property.
081 * </p>
082 * <ul>
083 * <li>
084 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
085 * Type is {@code java.lang.String[]}.
086 * Default value is {@code ""}.
087 * </li>
088 * <li>
089 * Property {@code lineSeparator} - Specify the type of line separator.
090 * Type is {@code com.puppycrawl.tools.checkstyle.checks.LineSeparatorOption}.
091 * Default value is {@code lf_cr_crlf}.
092 * </li>
093 * </ul>
094 *
095 * <p>
096 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
097 * </p>
098 *
099 * <p>
100 * Violation Message Keys:
101 * </p>
102 * <ul>
103 * <li>
104 * {@code noNewlineAtEOF}
105 * </li>
106 * <li>
107 * {@code unable.open}
108 * </li>
109 * <li>
110 * {@code wrong.line.end}
111 * </li>
112 * </ul>
113 *
114 * @since 3.1
115 */
116@StatelessCheck
117public class NewlineAtEndOfFileCheck
118    extends AbstractFileSetCheck {
119
120    /**
121     * A key is pointing to the warning message text in "messages.properties"
122     * file.
123     */
124    public static final String MSG_KEY_UNABLE_OPEN = "unable.open";
125
126    /**
127     * A key is pointing to the warning message text in "messages.properties"
128     * file.
129     */
130    public static final String MSG_KEY_NO_NEWLINE_EOF = "noNewlineAtEOF";
131
132    /**
133     * A key is pointing to the warning message text in "messages.properties"
134     * file.
135     */
136    public static final String MSG_KEY_WRONG_ENDING = "wrong.line.end";
137
138    /** Specify the type of line separator. */
139    private LineSeparatorOption lineSeparator = LineSeparatorOption.LF_CR_CRLF;
140
141    @Override
142    protected void processFiltered(File file, FileText fileText) {
143        try {
144            readAndCheckFile(file);
145        }
146        catch (final IOException ignored) {
147            log(1, MSG_KEY_UNABLE_OPEN, file.getPath());
148        }
149    }
150
151    /**
152     * Setter to specify the type of line separator.
153     *
154     * @param lineSeparatorParam The line separator to set
155     * @throws IllegalArgumentException If the specified line separator is not
156     *         one of 'crlf', 'lf', 'cr', 'lf_cr_crlf' or 'system'
157     * @since 3.1
158     */
159    public void setLineSeparator(String lineSeparatorParam) {
160        lineSeparator =
161            Enum.valueOf(LineSeparatorOption.class, lineSeparatorParam.trim()
162                .toUpperCase(Locale.ENGLISH));
163    }
164
165    /**
166     * Reads the file provided and checks line separators.
167     *
168     * @param file the file to be processed
169     * @throws IOException When an IO error occurred while reading from the
170     *         file provided
171     */
172    private void readAndCheckFile(File file) throws IOException {
173        // Cannot use lines as the line separators have been removed!
174        try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r")) {
175            if (lineSeparator == LineSeparatorOption.LF
176                    && endsWithNewline(randomAccessFile, LineSeparatorOption.CRLF)) {
177                log(1, MSG_KEY_WRONG_ENDING);
178            }
179            else if (!endsWithNewline(randomAccessFile, lineSeparator)) {
180                log(1, MSG_KEY_NO_NEWLINE_EOF);
181            }
182        }
183    }
184
185    /**
186     * Checks whether the content provided by the Reader ends with the platform
187     * specific line separator.
188     *
189     * @param file The reader for the content to check
190     * @param separator The line separator
191     * @return boolean Whether the content ends with a line separator
192     * @throws IOException When an IO error occurred while reading from the
193     *         provided reader
194     */
195    private static boolean endsWithNewline(RandomAccessFile file, LineSeparatorOption separator)
196            throws IOException {
197        final boolean result;
198        final int len = separator.length();
199        if (file.length() < len) {
200            result = false;
201        }
202        else {
203            file.seek(file.length() - len);
204            final byte[] lastBytes = new byte[len];
205            final int readBytes = file.read(lastBytes);
206            if (readBytes != len) {
207                throw new IOException("Unable to read " + len + " bytes, got "
208                        + readBytes);
209            }
210            result = separator.matches(lastBytes);
211        }
212        return result;
213    }
214
215}