Improve handling of relative file paths in report files

cxx-squid/src/main/java/org/sonar/cxx/utils/CxxReportLocation.java

@@ -19,6 +19,7 @@
  */
 package org.sonar.cxx.utils;
 
+import java.nio.file.Paths;
 import java.util.Objects;
 import javax.annotation.Nullable;
 import org.sonar.api.utils.PathUtils;
@@ -35,8 +36,19 @@ public class CxxReportLocation {
 
   public CxxReportLocation(@Nullable String file, @Nullable String line, @Nullable String column, String info) {
     super();
-    // normalize file, removing double and single dot path steps => avoids duplicates
-    this.file = PathUtils.sanitize(file);
+
+    // Normalize file using separators in UNIX format, removing double and single dot path steps. This is to avoid
+    // duplicates in the issue containers because they are using the file as key. PathUtils.sanitize uses
+    // FilenameUtils.normalize internally, relative paths starting with a double dot will cause that path segment
+    // and the one before to be removed. If the double dot has no parent path segment to work with, null is returned.
+    // null would mean 'project issue' which is wrong in this context. To avoid this we extract the filename to
+    // generate at least a meningful error message.
+    var normalized = PathUtils.sanitize(file);
+    if (normalized == null && (file != null && !file.isBlank())) {
+      normalized = Paths.get(file).getFileName().toString();
+    }
+
+    this.file = normalized;
     this.line = line;
     this.column = column;
     this.info = info;

cxx-squid/src/test/java/org/sonar/cxx/utils/CxxReportLocationTest.java

@@ -0,0 +1,78 @@
+/*
+ * C++ Community Plugin (cxx plugin)
+ * Copyright (C) 2010-2023 SonarOpenCommunity
+ * http://github.com/SonarOpenCommunity/sonar-cxx
+ *
+ * This program 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 3 of the License, or (at your option) any later version.
+ *
+ * This program 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 program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.cxx.utils;
+
+import static org.assertj.core.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+public class CxxReportLocationTest {
+
+  @Test
+  void testConstructor() {
+    var loc0 = new CxxReportLocation(null, null, null, "info");
+    assertThat(loc0.getFile()).isNull();
+    assertThat(loc0.getLine()).isNull();
+    assertThat(loc0.getColumn()).isNull();
+    assertThat(loc0.getInfo()).isEqualTo("info");
+    assertThat(loc0.toString()).isEqualTo("CxxReportLocation [file=null, line=null, column=null, info=info]");
+
+    var loc1 = new CxxReportLocation("file", "line", "column", "info");
+    assertThat(loc1.getFile()).isEqualTo("file");
+    assertThat(loc1.getLine()).isEqualTo("line");
+    assertThat(loc1.getColumn()).isEqualTo("column");
+    assertThat(loc1.getInfo()).isEqualTo("info");
+    assertThat(loc1.toString()).isEqualTo("CxxReportLocation [file=file, line=line, column=column, info=info]");
+  }
+
+  @Test
+  void testPathSanitize() {
+    var loc = new CxxReportLocation("file", null, null, "");
+
+    loc = new CxxReportLocation("/dir/File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("/dir/File");
+    loc = new CxxReportLocation("/dir/./File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("/dir/File");
+    loc = new CxxReportLocation("/dir/../File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("/File");
+    loc = new CxxReportLocation("dir/File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("dir/File");
+    loc = new CxxReportLocation("./dir/File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("dir/File");
+    loc = new CxxReportLocation("../dir/File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("File");
+    loc = new CxxReportLocation("../../File", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("File");
+
+    loc = new CxxReportLocation("c:\\dir\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("c:/dir/file.ext");
+    loc = new CxxReportLocation("C:\\dir\\.\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("C:/dir/file.ext");
+    loc = new CxxReportLocation("c:\\dir\\..\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("c:/file.ext");
+    loc = new CxxReportLocation("dir\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("dir/file.ext");
+    loc = new CxxReportLocation(".\\dir\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("dir/file.ext");
+    loc = new CxxReportLocation("..\\dir\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("file.ext");
+    loc = new CxxReportLocation("..\\..\\file.ext", null, null, "");
+    assertThat(loc.getFile()).isEqualTo("file.ext");
+  }
+}