Source code

001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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 * <p>
033 * Checks whether files end with a line separator.
034 * </p>
035 * <p>
036 * Rationale: Any source files and text files in general should end with a line
037 * separator to let other easily add new content at the end of file and "diff"
038 * command does not show previous lines as changed.
039 * </p>
040 * <p>
041 * Example (line 36 should not be in diff):
042 * </p>
043 * <pre>
044 * &#64;&#64; -32,4 +32,5 &#64;&#64; ForbidWildcardAsReturnTypeCheck.returnTypeClassNamesIgnoreRegex
045 * PublicReferenceToPrivateTypeCheck.name = Public Reference To Private Type
046 *
047 * StaticMethodCandidateCheck.name = Static Method Candidate
048 * -StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
049 * \ No newline at end of file
050 * +StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
051 * +StaticMethodCandidateCheck.skippedMethods = Method names to skip during the check.
052 * </pre>
053 * <p>
054 * It can also trick the VCS to report the wrong owner for such lines.
055 * An engineer who has added nothing but a newline character becomes the last
056 * known author for the entire line. As a result, a mate can ask him a question
057 * to which he will not give the correct answer.
058 * </p>
059 * <p>
060 * Old Rationale: CVS source control management systems will even print
061 * a warning when it encounters a file that doesn't end with a line separator.
062 * </p>
063 * <p>
064 * Attention: property fileExtensions works with files that are passed by similar
065 * property for at <a href="https://checkstyle.org/config.html#Checker">Checker</a>.
066 * Please make sure required file extensions are mentioned at Checker's fileExtensions property.
067 * </p>
068 * <p>
069 * This will check against the platform-specific default line separator.
070 * </p>
071 * <p>
072 * It is also possible to enforce the use of a specific line-separator across
073 * platforms, with the {@code lineSeparator} property.
074 * </p>
075 * <ul>
076 * <li>
077 * Property {@code lineSeparator} - Specify the type of line separator.
078 * Type is {@code com.puppycrawl.tools.checkstyle.checks.LineSeparatorOption}.
079 * Default value is {@code lf_cr_crlf}.
080 * </li>
081 * <li>
082 * Property {@code fileExtensions} - Specify the file type extension of the files to check.
083 * Type is {@code java.lang.String[]}.
084 * Default value is {@code all files}.
085 * </li>
086 * </ul>
087 * <p>
088 * To configure the check:
089 * </p>
090 * <pre>
091 * &lt;module name=&quot;NewlineAtEndOfFile&quot;/&gt;
092 * </pre>
093 * <p>Example:</p>
094 * <pre>
095 * // File ending with a new line
096 * public class Test {⤶
097 * ⤶
098 * }⤶ // ok
099 * Note: The comment // ok is a virtual, not actually present in the file
100 *
101 * // File ending without a new line
102 * public class Test1 {⤶
103 * ⤶
104 * } // violation, the file does not end with a new line
105 * </pre>
106 * <p>
107 * To configure the check to always use Unix-style line separators:
108 * </p>
109 * <pre>
110 * &lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
111 *   &lt;property name=&quot;lineSeparator&quot; value=&quot;lf&quot;/&gt;
112 * &lt;/module&gt;
113 * </pre>
114 * <p>Example:</p>
115 * <pre>
116 * // File ending with a new line
117 * public class Test {⤶
118 * ⤶
119 * }⤶ // ok
120 * Note: The comment // ok is a virtual, not actually present in the file
121 *
122 * // File ending without a new line
123 * public class Test1 {⤶
124 * ⤶
125 * }␍⤶ // violation, expected line ending for file is LF(\n), but CRLF(\r\n) is detected
126 * </pre>
127 * <p>
128 * To configure the check to work only on Java, XML and Python files:
129 * </p>
130 * <pre>
131 * &lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
132 *   &lt;property name=&quot;fileExtensions&quot; value=&quot;java, xml, py&quot;/&gt;
133 * &lt;/module&gt;
134 * </pre>
135 * <p>Example:</p>
136 * <pre>
137 * // Any java file
138 * public class Test {⤶
139 * } // violation, file should end with a new line.
140 *
141 * // Any py file
142 * print("Hello World") // violation, file should end with a new line.
143 *
144 * // Any txt file
145 * This is a sample text file. // ok, this file is not specified in the config.
146 * </pre>
147 * <p>
148 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
149 * </p>
150 * <p>
151 * Violation Message Keys:
152 * </p>
153 * <ul>
154 * <li>
155 * {@code noNewlineAtEOF}
156 * </li>
157 * <li>
158 * {@code unable.open}
159 * </li>
160 * <li>
161 * {@code wrong.line.end}
162 * </li>
163 * </ul>
164 *
165 * @since 3.1
166 */
167@StatelessCheck
168public class NewlineAtEndOfFileCheck
169    extends AbstractFileSetCheck {
170
171    /**
172     * A key is pointing to the warning message text in "messages.properties"
173     * file.
174     */
175    public static final String MSG_KEY_UNABLE_OPEN = "unable.open";
176
177    /**
178     * A key is pointing to the warning message text in "messages.properties"
179     * file.
180     */
181    public static final String MSG_KEY_NO_NEWLINE_EOF = "noNewlineAtEOF";
182
183    /**
184     * A key is pointing to the warning message text in "messages.properties"
185     * file.
186     */
187    public static final String MSG_KEY_WRONG_ENDING = "wrong.line.end";
188
189    /** Specify the type of line separator. */
190    private LineSeparatorOption lineSeparator = LineSeparatorOption.LF_CR_CRLF;
191
192    @Override
193    protected void processFiltered(File file, FileText fileText) {
194        try {
195            readAndCheckFile(file);
196        }
197        catch (final IOException ignored) {
198            log(1, MSG_KEY_UNABLE_OPEN, file.getPath());
199        }
200    }
201
202    /**
203     * Setter to specify the type of line separator.
204     *
205     * @param lineSeparatorParam The line separator to set
206     * @throws IllegalArgumentException If the specified line separator is not
207     *         one of 'crlf', 'lf', 'cr', 'lf_cr_crlf' or 'system'
208     */
209    public void setLineSeparator(String lineSeparatorParam) {
210        lineSeparator =
211            Enum.valueOf(LineSeparatorOption.class, lineSeparatorParam.trim()
212                .toUpperCase(Locale.ENGLISH));
213    }
214
215    /**
216     * Reads the file provided and checks line separators.
217     *
218     * @param file the file to be processed
219     * @throws IOException When an IO error occurred while reading from the
220     *         file provided
221     */
222    private void readAndCheckFile(File file) throws IOException {
223        // Cannot use lines as the line separators have been removed!
224        try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r")) {
225            if (lineSeparator == LineSeparatorOption.LF
226                    && endsWithNewline(randomAccessFile, LineSeparatorOption.CRLF)) {
227                log(1, MSG_KEY_WRONG_ENDING, file.getPath());
228            }
229            else if (!endsWithNewline(randomAccessFile, lineSeparator)) {
230                log(1, MSG_KEY_NO_NEWLINE_EOF, file.getPath());
231            }
232        }
233    }
234
235    /**
236     * Checks whether the content provided by the Reader ends with the platform
237     * specific line separator.
238     *
239     * @param file The reader for the content to check
240     * @param separator The line separator
241     * @return boolean Whether the content ends with a line separator
242     * @throws IOException When an IO error occurred while reading from the
243     *         provided reader
244     */
245    private static boolean endsWithNewline(RandomAccessFile file, LineSeparatorOption separator)
246            throws IOException {
247        final boolean result;
248        final int len = separator.length();
249        if (file.length() < len) {
250            result = false;
251        }
252        else {
253            file.seek(file.length() - len);
254            final byte[] lastBytes = new byte[len];
255            final int readBytes = file.read(lastBytes);
256            if (readBytes != len) {
257                throw new IOException("Unable to read " + len + " bytes, got "
258                        + readBytes);
259            }
260            result = separator.matches(lastBytes);
261        }
262        return result;
263    }
264
265}