SONAR-16544 Scanner fails if there's no git HEAD commit

3 files changed, 33 insertions, 1 deletions

diff --git a/sonar-scanner-engine/src/main/java/org/sonar/scm/git/CompositeBlameCommand.java b/sonar-scanner-engine/src/main/java/org/sonar/scm/git/CompositeBlameCommand.java
index a39b6401767..59cd3c40468 100644
--- a/sonar-scanner-engine/src/main/java/org/sonar/scm/git/CompositeBlameCommand.java
+++ b/sonar-scanner-engine/src/main/java/org/sonar/scm/git/CompositeBlameCommand.java
@@ -24,12 +24,14 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import org.eclipse.jgit.api.Git;
 import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
@@ -43,6 +45,8 @@ import org.sonar.api.utils.log.Logger;
 import org.sonar.api.utils.log.Loggers;
 import org.sonar.api.utils.log.Profiler;
 
+import static java.util.Optional.ofNullable;
+
 public class CompositeBlameCommand extends BlameCommand {
   private static final Logger LOG = Loggers.get(CompositeBlameCommand.class);
 
@@ -96,9 +100,15 @@ public class CompositeBlameCommand extends BlameCommand {
   private static Set<String> collectAllCommittedFiles(Repository repo) {
     try {
       Set<String> files = new HashSet<>();
+      Optional<ObjectId> headCommit = ofNullable(repo.resolve(Constants.HEAD));
+
+      if (headCommit.isEmpty()) {
+        LOG.warn("Could not find HEAD commit");
+        return files;
+      }
 
       try (RevWalk revWalk = new RevWalk(repo)) {
-        RevCommit head = revWalk.parseCommit(repo.resolve(Constants.HEAD));
+        RevCommit head = revWalk.parseCommit(headCommit.get());
         try (TreeWalk treeWalk = new TreeWalk(repo)) {
           treeWalk.addTree(head.getTree());
           treeWalk.setRecursive(true);
diff --git a/sonar-scanner-engine/src/test/java/org/sonar/scm/git/CompositeBlameCommandTest.java b/sonar-scanner-engine/src/test/java/org/sonar/scm/git/CompositeBlameCommandTest.java
index 5ed16c963de..792b501e093 100644
--- a/sonar-scanner-engine/src/test/java/org/sonar/scm/git/CompositeBlameCommandTest.java
+++ b/sonar-scanner-engine/src/test/java/org/sonar/scm/git/CompositeBlameCommandTest.java
@@ -132,6 +132,28 @@ public class CompositeBlameCommandTest {
   }
 
   @Test
+  public void skip_files_when_head_commit_is_missing() throws IOException {
+    // skip if git not installed
+    assumeTrue(gitBlameCommand.checkIfEnabled());
+
+    JGitBlameCommand jgit = mock(JGitBlameCommand.class);
+    BlameCommand blameCmd = new CompositeBlameCommand(analysisWarnings, pathResolver, jgit, gitBlameCommand);
+    File projectDir = createNewTempFolder();
+    javaUnzip("no-head-git.zip", projectDir);
+
+    File baseDir = new File(projectDir, "no-head-git");
+    setUpBlameInputWithFile(baseDir.toPath());
+    TestBlameOutput output = new TestBlameOutput();
+    blameCmd.blame(input, output);
+
+    assertThat(output.blame).isEmpty();
+    verifyNoInteractions(jgit);
+
+    assertThat(logTester.logs())
+      .contains("Could not find HEAD commit");
+  }
+
+  @Test
   public void use_native_git_by_default() throws IOException {
     // skip test if git is not installed
     assumeTrue(gitBlameCommand.checkIfEnabled());
diff --git a/sonar-scanner-engine/src/test/resources/org/sonar/scm/git/test-repos/no-head-git.zip b/sonar-scanner-engine/src/test/resources/org/sonar/scm/git/test-repos/no-head-git.zip
new file mode 100644
index 00000000000..d63ef865c54
--- /dev/null
+++ b/sonar-scanner-engine/src/test/resources/org/sonar/scm/git/test-repos/no-head-git.zip