Unify fetch and receive ObjectChecker setup

This avoids duplication of code between receive-pack and fetch-pack paths.
Separate methods are still required to check use of receive.fsckobjects vs.
fetch.fsckobjects, both of which default to transfer.fsckobjects.

Change-Id: I41193e093e981a79fc2f63914e273aaa44b82162

org.eclipse.jgit/src/org/eclipse/jgit/transport/BaseReceivePack.java

 		db = into;
 		walk = new RevWalk(db);
 
-		final ReceiveConfig cfg = db.getConfig().get(ReceiveConfig.KEY);
-		objectChecker = cfg.newObjectChecker();
-		allowCreates = cfg.allowCreates;
+		TransferConfig tc = db.getConfig().get(TransferConfig.KEY);
+		objectChecker = tc.newReceiveObjectChecker();
+
+		ReceiveConfig rc = db.getConfig().get(ReceiveConfig.KEY);
+		allowCreates = rc.allowCreates;
 		allowAnyDeletes = true;
-		allowBranchDeletes = cfg.allowDeletes;
-		allowNonFastForwards = cfg.allowNonFastForwards;
-		allowOfsDelta = cfg.allowOfsDelta;
+		allowBranchDeletes = rc.allowDeletes;
+		allowNonFastForwards = rc.allowNonFastForwards;
+		allowOfsDelta = rc.allowOfsDelta;
 		advertiseRefsHook = AdvertiseRefsHook.DEFAULT;
 		refFilter = RefFilter.DEFAULT;
 		advertisedHaves = new HashSet<ObjectId>();
 		clientShallowCommits = new HashSet<ObjectId>();
-		signedPushConfig = cfg.signedPush;
+		signedPushConfig = rc.signedPush;
 	}
 
 	/** Configuration for receive operations. */
 			}
 		};
 
-		final boolean checkReceivedObjects;
-		final boolean allowLeadingZeroFileMode;
-		final boolean allowInvalidPersonIdent;
-		final boolean safeForWindows;
-		final boolean safeForMacOS;
-
 		final boolean allowCreates;
 		final boolean allowDeletes;
 		final boolean allowNonFastForwards;
 		final boolean allowOfsDelta;
-
 		final SignedPushConfig signedPush;
 
 		ReceiveConfig(final Config config) {
-			checkReceivedObjects = config.getBoolean(
-					"receive", "fsckobjects", //$NON-NLS-1$ //$NON-NLS-2$
-					config.getBoolean("transfer", "fsckobjects", false)); //$NON-NLS-1$ //$NON-NLS-2$
-			allowLeadingZeroFileMode = checkReceivedObjects
-					&& config.getBoolean("fsck", "allowLeadingZeroFileMode", false); //$NON-NLS-1$ //$NON-NLS-2$
-			allowInvalidPersonIdent = checkReceivedObjects
-					&& config.getBoolean("fsck", "allowInvalidPersonIdent", false); //$NON-NLS-1$ //$NON-NLS-2$
-			safeForWindows = checkReceivedObjects
-					&& config.getBoolean("fsck", "safeForWindows", false); //$NON-NLS-1$ //$NON-NLS-2$
-			safeForMacOS = checkReceivedObjects
-					&& config.getBoolean("fsck", "safeForMacOS", false); //$NON-NLS-1$ //$NON-NLS-2$
-
 			allowCreates = true;
 			allowDeletes = !config.getBoolean("receive", "denydeletes", false); //$NON-NLS-1$ //$NON-NLS-2$
 			allowNonFastForwards = !config.getBoolean("receive", //$NON-NLS-1$
 					true);
 			signedPush = SignedPushConfig.KEY.parse(config);
 		}
-
-		ObjectChecker newObjectChecker() {
-			if (!checkReceivedObjects)
-				return null;
-			return new ObjectChecker()
-				.setAllowLeadingZeroFileMode(allowLeadingZeroFileMode)
-				.setAllowInvalidPersonIdent(allowInvalidPersonIdent)
-				.setSafeForWindows(safeForWindows)
-				.setSafeForMacOS(safeForMacOS);
-		}
 	}
 
 	/**

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransferConfig.java

 import java.util.HashMap;
 import java.util.Map;
 
+import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Config.SectionParser;
 import org.eclipse.jgit.lib.ObjectChecker;
 		}
 	};
 
-	private final boolean checkReceivedObjects;
+	private final boolean fetchFsck;
+	private final boolean receiveFsck;
 	private final boolean allowLeadingZeroFileMode;
 	private final boolean allowInvalidPersonIdent;
 	private final boolean safeForWindows;
 	}
 
 	TransferConfig(final Config rc) {
-		checkReceivedObjects = rc.getBoolean(
-				"fetch", "fsckobjects", //$NON-NLS-1$ //$NON-NLS-2$
-				rc.getBoolean("transfer", "fsckobjects", false)); //$NON-NLS-1$ //$NON-NLS-2$
-		allowLeadingZeroFileMode = checkReceivedObjects
-				&& rc.getBoolean("fsck", "allowLeadingZeroFileMode", false); //$NON-NLS-1$ //$NON-NLS-2$
-		allowInvalidPersonIdent = checkReceivedObjects
-				&& rc.getBoolean("fsck", "allowInvalidPersonIdent", false); //$NON-NLS-1$ //$NON-NLS-2$
-		safeForWindows = checkReceivedObjects
-				&& rc.getBoolean("fsck", "safeForWindows", //$NON-NLS-1$ //$NON-NLS-2$
+		boolean fsck = rc.getBoolean("transfer", "fsckobjects", false); //$NON-NLS-1$ //$NON-NLS-2$
+		fetchFsck = rc.getBoolean("fetch", "fsckobjects", fsck); //$NON-NLS-1$ //$NON-NLS-2$
+		receiveFsck = rc.getBoolean("receive", "fsckobjects", fsck); //$NON-NLS-1$ //$NON-NLS-2$
+		allowLeadingZeroFileMode = rc.getBoolean("fsck", "allowLeadingZeroFileMode", false); //$NON-NLS-1$ //$NON-NLS-2$
+		allowInvalidPersonIdent = rc.getBoolean("fsck", "allowInvalidPersonIdent", false); //$NON-NLS-1$ //$NON-NLS-2$
+		safeForWindows = rc.getBoolean("fsck", "safeForWindows", //$NON-NLS-1$ //$NON-NLS-2$
 						SystemReader.getInstance().isWindows());
-		safeForMacOS = checkReceivedObjects
-				&& rc.getBoolean("fsck", "safeForMacOS", //$NON-NLS-1$ //$NON-NLS-2$
+		safeForMacOS = rc.getBoolean("fsck", "safeForMacOS", //$NON-NLS-1$ //$NON-NLS-2$
 						SystemReader.getInstance().isMacOS());
 
 		allowTipSha1InWant = rc.getBoolean(
 	 *         enabled in the repository configuration.
 	 * @since 3.6
 	 */
+	@Nullable
 	public ObjectChecker newObjectChecker() {
-		if (!checkReceivedObjects)
+		return newObjectChecker(fetchFsck);
+	}
+
+	/**
+	 * @return checker to verify objects pushed into this repository, or null if
+	 *         checking is not enabled in the repository configuration.
+	 * @since 4.2
+	 */
+	@Nullable
+	public ObjectChecker newReceiveObjectChecker() {
+		return newObjectChecker(receiveFsck);
+	}
+
+	private ObjectChecker newObjectChecker(boolean check) {
+		if (!check) {
 			return null;
+		}
 		return new ObjectChecker()
 			.setAllowLeadingZeroFileMode(allowLeadingZeroFileMode)
 			.setAllowInvalidPersonIdent(allowInvalidPersonIdent)