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 * Default value is {@code lf_cr_crlf}.
079 * </li>
080 * <li>
081 * Property {@code fileExtensions} - Specify the file type extension of the files to check.
082 * Default value is {@code all files}.
083 * </li>
084 * </ul>
085 * <p>
086 * To configure the check:
087 * </p>
088 * <pre>
089 * &lt;module name=&quot;NewlineAtEndOfFile&quot;/&gt;
090 * </pre>
091 * <p>Example:</p>
092 * <pre>
093 * // File ending with a new line
094 * public class Test {⤶
095 * ⤶
096 * }⤶ // ok
097 * Note: The comment // ok is a virtual, not actually present in the file
098 *
099 * // File ending without a new line
100 * public class Test1 {⤶
101 * ⤶
102 * } // violation, the file does not end with a new line
103 * </pre>
104 * <p>
105 * To configure the check to always use Unix-style line separators:
106 * </p>
107 * <pre>
108 * &lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
109 *   &lt;property name=&quot;lineSeparator&quot; value=&quot;lf&quot;/&gt;
110 * &lt;/module&gt;
111 * </pre>
112 * <p>Example:</p>
113 * <pre>
114 * // File ending with a new line
115 * public class Test {⤶
116 * ⤶
117 * }⤶ // ok
118 * Note: The comment // ok is a virtual, not actually present in the file
119 *
120 * // File ending without a new line
121 * public class Test1 {⤶
122 * ⤶
123 * }␍⤶ // violation, expected line ending for file is LF(\n), but CRLF(\r\n) is detected
124 * </pre>
125 * <p>
126 * To configure the check to work only on Java, XML and Python files:
127 * </p>
128 * <pre>
129 * &lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
130 *   &lt;property name=&quot;fileExtensions&quot; value=&quot;java, xml, py&quot;/&gt;
131 * &lt;/module&gt;
132 * </pre>
133 * <p>Example:</p>
134 * <pre>
135 * // Any java file
136 * public class Test {⤶
137 * } // violation, file should end with a new line.
138 *
139 * // Any py file
140 * print("Hello World") // violation, file should end with a new line.
141 *
142 * // Any txt file
143 * This is a sample text file. // ok, this file is not specified in the config.
144 * </pre>
145 *
146 * @since 3.1
147 */
148@StatelessCheck
149public class NewlineAtEndOfFileCheck
150    extends AbstractFileSetCheck {
151
152    /**
153     * A key is pointing to the warning message text in "messages.properties"
154     * file.
155     */
156    public static final String MSG_KEY_UNABLE_OPEN = "unable.open";
157
158    /**
159     * A key is pointing to the warning message text in "messages.properties"
160     * file.
161     */
162    public static final String MSG_KEY_NO_NEWLINE_EOF = "noNewlineAtEOF";
163
164    /**
165     * A key is pointing to the warning message text in "messages.properties"
166     * file.
167     */
168    public static final String MSG_KEY_WRONG_ENDING = "wrong.line.end";
169
170    /** Specify the type of line separator. */
171    private LineSeparatorOption lineSeparator = LineSeparatorOption.LF_CR_CRLF;
172
173    @Override
174    protected void processFiltered(File file, FileText fileText) {
175        try {
176            readAndCheckFile(file);
177        }
178        catch (final IOException ignored) {
179            log(1, MSG_KEY_UNABLE_OPEN, file.getPath());
180        }
181    }
182
183    /**
184     * Setter to specify the type of line separator.
185     *
186     * @param lineSeparatorParam The line separator to set
187     * @throws IllegalArgumentException If the specified line separator is not
188     *         one of 'crlf', 'lf', 'cr', 'lf_cr_crlf' or 'system'
189     */
190    public void setLineSeparator(String lineSeparatorParam) {
191        lineSeparator =
192            Enum.valueOf(LineSeparatorOption.class, lineSeparatorParam.trim()
193                .toUpperCase(Locale.ENGLISH));
194    }
195
196    /**
197     * Reads the file provided and checks line separators.
198     *
199     * @param file the file to be processed
200     * @throws IOException When an IO error occurred while reading from the
201     *         file provided
202     */
203    private void readAndCheckFile(File file) throws IOException {
204        // Cannot use lines as the line separators have been removed!
205        try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r")) {
206            if (lineSeparator == LineSeparatorOption.LF
207                    && endsWithNewline(randomAccessFile, LineSeparatorOption.CRLF)) {
208                log(1, MSG_KEY_WRONG_ENDING, file.getPath());
209            }
210            else if (!endsWithNewline(randomAccessFile, lineSeparator)) {
211                log(1, MSG_KEY_NO_NEWLINE_EOF, file.getPath());
212            }
213        }
214    }
215
216    /**
217     * Checks whether the content provided by the Reader ends with the platform
218     * specific line separator.
219     *
220     * @param file The reader for the content to check
221     * @param separator The line separator
222     * @return boolean Whether the content ends with a line separator
223     * @throws IOException When an IO error occurred while reading from the
224     *         provided reader
225     */
226    private static boolean endsWithNewline(RandomAccessFile file, LineSeparatorOption separator)
227            throws IOException {
228        final boolean result;
229        final int len = separator.length();
230        if (file.length() < len) {
231            result = false;
232        }
233        else {
234            file.seek(file.length() - len);
235            final byte[] lastBytes = new byte[len];
236            final int readBytes = file.read(lastBytes);
237            if (readBytes != len) {
238                throw new IOException("Unable to read " + len + " bytes, got "
239                        + readBytes);
240            }
241            result = separator.matches(lastBytes);
242        }
243        return result;
244    }
245
246}