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 * @@ -32,4 +32,5 @@ 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}