[JENKINS-40834] Bingo! A nasty hack gets us the symref info for JGit …

…pending their implementation of same
jenkinsci · Mar 22, 2017 · 2cb2fc1 · 2cb2fc1
1 parent 64f4303
commit 2cb2fc1
Showing 1 changed file with 47 additions and 0 deletions.
diff --git a/src/main/java/org/jenkinsci/plugins/gitclient/JGitAPIImpl.java b/src/main/java/org/jenkinsci/plugins/gitclient/JGitAPIImpl.java
@@ -30,7 +30,9 @@
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.io.Writer;
+import java.lang.reflect.Field;
 import java.net.URISyntaxException;
+import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -62,6 +64,7 @@
 import org.eclipse.jgit.api.ShowNoteCommand;
 import org.eclipse.jgit.api.errors.CheckoutConflictException;
 import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.api.errors.InvalidRemoteException;
 import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.diff.DiffEntry;
 import org.eclipse.jgit.diff.DiffEntry.ChangeType;
@@ -71,6 +74,7 @@
 import org.eclipse.jgit.errors.NotSupportedException;
 import org.eclipse.jgit.errors.TransportException;
 import org.eclipse.jgit.fnmatch.FileNameMatcher;
+import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.file.FileRepository;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Constants;
@@ -98,6 +102,7 @@
 import org.eclipse.jgit.revwalk.filter.MaxCountRevFilter;
 import org.eclipse.jgit.revwalk.filter.RevFilter;
 import org.eclipse.jgit.submodule.SubmoduleWalk;
+import org.eclipse.jgit.transport.BasePackFetchConnection;
 import org.eclipse.jgit.transport.CredentialsProvider;
 import org.eclipse.jgit.transport.FetchConnection;
 import org.eclipse.jgit.transport.HttpTransport;
@@ -801,10 +806,52 @@ public Map<String, String> getRemoteSymbolicReferences(String url, String patter
             return references;
         }
         try (Repository repo = openDummyRepository()) {
+            try {
+                // HACK HACK HACK
+                // The symref info is advertised as a capability starting from git 1.8.5
+                // So all we need to do is ask JGit to fetch the refs and then (because JGit adds all capabilities
+                // into a Set) we iterate the resulting set to find any that matching symref=$symref:$realref
+                // of course JGit does not expose a way to iterate the capabilities, so instead we have to hack
+                // and peek inside
+                // TODO if JGit implement https://bugs.eclipse.org/bugs/show_bug.cgi?id=514052 we should switch to that
+                Class<?> basePackConnection = BasePackFetchConnection.class.getSuperclass();
+                Field remoteCapablities = basePackConnection.getDeclaredField("remoteCapablities");
+                remoteCapablities.setAccessible(true);
+                try (Transport transport = Transport.open(repo, url)) {
+                    transport.setCredentialsProvider(getProvider());
+                    try (FetchConnection fc = transport.openFetch()) {
+                        fc.getRefs();
+                        if (fc instanceof BasePackFetchConnection) {
+                            Object o = remoteCapablities.get(fc);
+                            if (o instanceof Set) {
+                                boolean hackWorked = false;
+                                for (String capability: (Set<String>)o) {
+                                    if (capability.startsWith("symref=")) {
+                                        hackWorked = true;
+                                        int index = capability.indexOf(":", 7);
+                                        if (index != -1) {
+                                            references.put(capability.substring(7, index), capability.substring(index+1));
+                                        }
+                                    }
+                                }
+                                if (hackWorked) {
+                                    return references;
+                                }
+                            }
+                        }
+                    }
+                } catch (URISyntaxException | NotSupportedException | TransportException e) {
+                    // ignore this is a total hack
+                }
+            } catch (IllegalAccessException | NoSuchFieldException e) {
+                // ignore, we just have to try it the Git 1.8.4 way
+            }
+
             LsRemoteCommand lsRemote = new LsRemoteCommand(repo);
             lsRemote.setRemote(url);
             lsRemote.setCredentialsProvider(getProvider());
             Map<String, Ref> refs = lsRemote.callAsMap();
+
             Ref target = refs.get(Constants.HEAD);
             if (target == null) {
                 return references;