NewlineAtEndOfFileCheck.java
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.Locale;
import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
import com.puppycrawl.tools.checkstyle.api.FileText;
/**
* <p>
* Checks whether files end with a line separator.
* </p>
* <p>
* Rationale: Any source files and text files in general should end with a line
* separator to let other easily add new content at the end of file and "diff"
* command does not show previous lines as changed.
* </p>
* <p>
* Example (line 36 should not be in diff):
* </p>
* <pre>
* @@ -32,4 +32,5 @@ ForbidWildcardAsReturnTypeCheck.returnTypeClassNamesIgnoreRegex
* PublicReferenceToPrivateTypeCheck.name = Public Reference To Private Type
*
* StaticMethodCandidateCheck.name = Static Method Candidate
* -StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
* \ No newline at end of file
* +StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
* +StaticMethodCandidateCheck.skippedMethods = Method names to skip during the check.
* </pre>
* <p>
* It can also trick the VCS to report the wrong owner for such lines.
* An engineer who has added nothing but a newline character becomes the last
* known author for the entire line. As a result, a mate can ask him a question
* to which he will not give the correct answer.
* </p>
* <p>
* Old Rationale: CVS source control management systems will even print
* a warning when it encounters a file that doesn't end with a line separator.
* </p>
* <p>
* Attention: property fileExtensions works with files that are passed by similar
* property for at <a href="https://checkstyle.org/config.html#Checker">Checker</a>.
* Please make sure required file extensions are mentioned at Checker's fileExtensions property.
* </p>
* <p>
* This will check against the platform-specific default line separator.
* </p>
* <p>
* It is also possible to enforce the use of a specific line-separator across
* platforms, with the {@code lineSeparator} property.
* </p>
* <ul>
* <li>
* Property {@code lineSeparator} - Specify the type of line separator.
* Type is {@code com.puppycrawl.tools.checkstyle.checks.LineSeparatorOption}.
* Default value is {@code lf_cr_crlf}.
* </li>
* <li>
* Property {@code fileExtensions} - Specify the file type extension of the files to check.
* Type is {@code java.lang.String[]}.
* Default value is {@code ""}.
* </li>
* </ul>
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="NewlineAtEndOfFile"/>
* </pre>
* <p>Example:</p>
* <pre>
* // File ending with a new line
* public class Test {⤶
* ⤶
* }⤶ // ok
* Note: The comment // ok is a virtual, not actually present in the file
*
* // File ending without a new line
* public class Test1 {⤶
* ⤶
* } // violation, the file does not end with a new line
* </pre>
* <p>
* To configure the check to always use Unix-style line separators:
* </p>
* <pre>
* <module name="NewlineAtEndOfFile">
* <property name="lineSeparator" value="lf"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* // File ending with a new line
* public class Test {⤶
* ⤶
* }⤶ // ok
* Note: The comment // ok is a virtual, not actually present in the file
*
* // File ending without a new line
* public class Test1 {⤶
* ⤶
* }␍⤶ // violation, expected line ending for file is LF(\n), but CRLF(\r\n) is detected
* </pre>
* <p>
* To configure the check to work only on Java, XML and Python files:
* </p>
* <pre>
* <module name="NewlineAtEndOfFile">
* <property name="fileExtensions" value="java, xml, py"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* // Any java file
* public class Test {⤶
* } // violation, file should end with a new line.
*
* // Any py file
* print("Hello World") // violation, file should end with a new line.
*
* // Any txt file
* This is a sample text file. // ok, this file is not specified in the config.
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code noNewlineAtEOF}
* </li>
* <li>
* {@code unable.open}
* </li>
* <li>
* {@code wrong.line.end}
* </li>
* </ul>
*
* @since 3.1
*/
@StatelessCheck
public class NewlineAtEndOfFileCheck
extends AbstractFileSetCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY_UNABLE_OPEN = "unable.open";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY_NO_NEWLINE_EOF = "noNewlineAtEOF";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY_WRONG_ENDING = "wrong.line.end";
/** Specify the type of line separator. */
private LineSeparatorOption lineSeparator = LineSeparatorOption.LF_CR_CRLF;
@Override
protected void processFiltered(File file, FileText fileText) {
try {
readAndCheckFile(file);
}
catch (final IOException ignored) {
log(1, MSG_KEY_UNABLE_OPEN, file.getPath());
}
}
/**
* Setter to specify the type of line separator.
*
* @param lineSeparatorParam The line separator to set
* @throws IllegalArgumentException If the specified line separator is not
* one of 'crlf', 'lf', 'cr', 'lf_cr_crlf' or 'system'
*/
public void setLineSeparator(String lineSeparatorParam) {
lineSeparator =
Enum.valueOf(LineSeparatorOption.class, lineSeparatorParam.trim()
.toUpperCase(Locale.ENGLISH));
}
/**
* Reads the file provided and checks line separators.
*
* @param file the file to be processed
* @throws IOException When an IO error occurred while reading from the
* file provided
*/
private void readAndCheckFile(File file) throws IOException {
// Cannot use lines as the line separators have been removed!
try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r")) {
if (lineSeparator == LineSeparatorOption.LF
&& endsWithNewline(randomAccessFile, LineSeparatorOption.CRLF)) {
log(1, MSG_KEY_WRONG_ENDING, file.getPath());
}
else if (!endsWithNewline(randomAccessFile, lineSeparator)) {
log(1, MSG_KEY_NO_NEWLINE_EOF, file.getPath());
}
}
}
/**
* Checks whether the content provided by the Reader ends with the platform
* specific line separator.
*
* @param file The reader for the content to check
* @param separator The line separator
* @return boolean Whether the content ends with a line separator
* @throws IOException When an IO error occurred while reading from the
* provided reader
*/
private static boolean endsWithNewline(RandomAccessFile file, LineSeparatorOption separator)
throws IOException {
final boolean result;
final int len = separator.length();
if (file.length() < len) {
result = false;
}
else {
file.seek(file.length() - len);
final byte[] lastBytes = new byte[len];
final int readBytes = file.read(lastBytes);
if (readBytes != len) {
throw new IOException("Unable to read " + len + " bytes, got "
+ readBytes);
}
result = separator.matches(lastBytes);
}
return result;
}
}