Use FileSnapshot without using configs for FileBasedConfigstable-5.1

FileBasedConfig should not rely on auto-detection of
the file-snapshot attribute computation based on config.

The check was already performed when a new FileBasedConfig
is created at L158:

// don't use config in this snapshot to avoid endless recursion
newSnapshot = FileSnapshot.saveNoConfig(getFile());

The check was missing though when the FileBasedConfig is saved
to disk and the new snapshot is obtained from the associated
LockFile.

This change fixes the issue by keeping a non-config based
FileSnapshot also after a FileBasedConfig is saved.

Bug: 577983
Change-Id: Id1e410ba687e683ff2b2643af31e1110b103b356

3 files changed, 62 insertions, 5 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
index f3cd61da69..cfb2735a04 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
@@ -46,6 +46,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.eclipse.jgit.util.FileUtils.pathToString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -53,6 +54,8 @@ import java.io.OutputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.junit.MockSystemReader;
@@ -82,11 +85,13 @@ public class FileBasedConfigTest {
 
 	private Path trash;
 
+	private MockSystemReader mockSystemReader;
+
 	@Before
 	public void setUp() throws Exception {
-		SystemReader.setInstance(new MockSystemReader());
+		mockSystemReader = new MockSystemReader();
+		SystemReader.setInstance(mockSystemReader);
 		trash = Files.createTempDirectory("tmp_");
-		FS.getFileStoreAttributes(trash.getParent());
 	}
 
 	@After
@@ -245,6 +250,37 @@ public class FileBasedConfigTest {
 		assertEquals(ALICE, config.getString(USER, null, NAME));
 	}
 
+	@Test
+	public void testSavedConfigFileShouldNotReadUserGitConfig()
+			throws IOException {
+		AtomicBoolean userConfigTimeRead = new AtomicBoolean(false);
+
+		Path userConfigFile = createFile(CONTENT1.getBytes(), "home");
+		mockSystemReader.setUserGitConfig(
+				new FileBasedConfig(userConfigFile.toFile(), FS.DETECTED) {
+
+					@Override
+					public long getTimeUnit(String section, String subsection,
+							String name, long defaultValue, TimeUnit wantUnit) {
+						userConfigTimeRead.set(true);
+						return super.getTimeUnit(section, subsection, name,
+								defaultValue, wantUnit);
+					}
+				});
+
+		Path file = createFile(CONTENT2.getBytes(), "repo");
+		FileBasedConfig fileBasedConfig = new FileBasedConfig(file.toFile(),
+				FS.DETECTED);
+		fileBasedConfig.save();
+
+		// Needed to trigger the read of FileSnapshot filesystem settings
+		fileBasedConfig.isOutdated();
+		assertFalse(
+				"User config should not be read when accessing config files "
+						+ "for avoiding deadlocks",
+				userConfigTimeRead.get());
+	}
+
 	private Path createFile(byte[] content) throws IOException {
 		return createFile(content, null);
 	}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/LockFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/LockFile.java
index f7e78b94f7..548ea5af55 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/LockFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/LockFile.java
@@ -137,6 +137,8 @@ public class LockFile {
 
 	private boolean needSnapshot;
 
+	private boolean snapshotNoConfig;
+
 	boolean fsync;
 
 	private FileSnapshot commitSnapshot;
@@ -407,6 +409,21 @@ public class LockFile {
 	}
 
 	/**
+	 * Request that {@link #commit()} remember the
+	 * {@link org.eclipse.jgit.internal.storage.file.FileSnapshot} without using
+	 * config file to get filesystem timestamp resolution.
+	 * This method should be invoked before the file is accessed.
+	 * It is used by FileBasedConfig to avoid endless recursion.
+	 *
+	 * @param on
+	 *            true if the commit method must remember the FileSnapshot.
+	 */
+	public void setNeedSnapshotNoConfig(boolean on) {
+		needSnapshot = on;
+		snapshotNoConfig = on;
+	}
+
+	/**
 	 * Request that {@link #commit()} force dirty data to the drive.
 	 *
 	 * @param on
@@ -482,8 +499,12 @@ public class LockFile {
 	}
 
 	private void saveStatInformation() {
-		if (needSnapshot)
-			commitSnapshot = FileSnapshot.save(lck);
+		if (needSnapshot) {
+			commitSnapshot = snapshotNoConfig ?
+				// don't use config in this snapshot to avoid endless recursion
+				FileSnapshot.saveNoConfig(lck)
+				: FileSnapshot.save(lck);
+		}
 	}
 
 	/**
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java
index e7b0941f2d..34829a226b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java
@@ -236,7 +236,7 @@ public class FileBasedConfig extends StoredConfig {
 		if (!lf.lock())
 			throw new LockFailedException(getFile());
 		try {
-			lf.setNeedSnapshot(true);
+			lf.setNeedSnapshotNoConfig(true);
 			lf.write(out);
 			if (!lf.commit())
 				throw new IOException(MessageFormat.format(JGitText.get().cannotCommitWriteTo, getFile()));