patchDisambiguate "push not supported" from "repository not found"

org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java, org.spearce.jgit/src/org/spearce/jgit/transport/BasePackPushConnection.java

diff --git a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
index de0c7b6..e35f850 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
@@ -72,6 +72,9 @@
 	/** Remote repository location. */
 	protected final URIish uri;
 
+	/** A transport connected to {@link #uri}. */
+	protected final PackTransport transport;
+
 	/** Buffered input stream reading from the remote. */
 	protected InputStream in;
 
@@ -93,6 +96,7 @@
 	BasePackConnection(final PackTransport packTransport) {
 		local = packTransport.local;
 		uri = packTransport.uri;
+		transport = packTransport;
 	}
 
 	protected void init(final InputStream myIn, final OutputStream myOut) {
@@ -129,15 +133,8 @@ private void readAdvertisedRefsImpl() throws IOException {
 			try {
 				line = pckIn.readString();
 			} catch (EOFException eof) {
-				if (avail.isEmpty()) {
-					String service = "unknown";
-					if (this instanceof PushConnection)
-						service = "push";
-					else if (this instanceof FetchConnection)
-						service = "fetch";
-					throw new NoRemoteRepositoryException(uri, service
-							+ " service not found.");
-				}
+				if (avail.isEmpty())
+					throw noRepository();
 				throw eof;
 			}
 
@@ -185,6 +182,10 @@ else if (this instanceof FetchConnection)
 		available(avail);
 	}
 
+	protected TransportException noRepository() {
+		return new NoRemoteRepositoryException(uri, "not found.");
+	}
+
 	protected boolean isCapableOf(final String option) {
 		return remoteCapablities.contains(option);
 	}
diff --git a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackPushConnection.java b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackPushConnection.java
index a2d5b6f..a6ab9c4 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackPushConnection.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackPushConnection.java
@@ -43,6 +43,8 @@
 import java.util.Collection;
 import java.util.Map;
 
+import org.spearce.jgit.errors.NoRemoteRepositoryException;
+import org.spearce.jgit.errors.NotSupportedException;
 import org.spearce.jgit.errors.PackProtocolException;
 import org.spearce.jgit.errors.TransportException;
 import org.spearce.jgit.lib.ObjectId;
@@ -98,6 +100,29 @@ public void push(final ProgressMonitor monitor,
 		doPush(monitor, refUpdates);
 	}
 
+	@Override
+	protected TransportException noRepository() {
+		// Sadly we cannot tell the "invalid URI" case from "push not allowed".
+		// Opening a fetch connection can help us tell the difference, as any
+		// useful repository is going to support fetch if it also would allow
+		// push. So if fetch throws NoRemoteRepositoryException we know the
+		// URI is wrong. Otherwise we can correctly state push isn't allowed
+		// as the fetch connection opened successfully.
+		//
+		try {
+			transport.openFetch().close();
+		} catch (NotSupportedException e) {
+			// Fall through.
+		} catch (NoRemoteRepositoryException e) {
+			// Fetch concluded the repository doesn't exist.
+			//
+			return e;
+		} catch (TransportException e) {
+			// Fall through.
+		}
+		return new TransportException(uri, "push not permitted");
+	}
+
 	protected void doPush(final ProgressMonitor monitor,
 			final Map<String, RemoteRefUpdate> refUpdates)
 			throws TransportException {

diff --git a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
index e35f850..16e4897 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackConnection.java
@@ -182,6 +182,15 @@ private void readAdvertisedRefsImpl() throws IOException {
                available(avail);
        }

+       /**
+        * Create an exception to indicate problems finding a remote repository. The
+        * caller is expected to throw the returned exception.
+        *
+        * Subclasses may override this method to provide better diagnostics.
+        *
+        * @return a TransportException saying a repository cannot be found and
+        *         possibly why.
+        */
        protected TransportException noRepository() {
                return new NoRemoteRepositoryException(uri, "not found.");
        }