Add type selection fallback for fs open.

Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/FileSystemService.java

@@ -962,4 +962,17 @@ public synchronized CryptoSession newCryptoSession() {
 		return new CryptoProviderSessionChildImpl(currentCryptoSession);
 	}
 
+	/**
+	 * Adds the given {@link GFileSystem} instance to the managed filesystems list.
+	 *
+	 * @param fs {@link GFileSystem} to add to the managed filesystems list.
+	 */
+	public void addFileSystem(GFileSystem fs) {
+		synchronized (fsInstanceManager) {
+			if (!isFilesystemMountedAt(fs.getFSRL())) {
+				fsInstanceManager.add(fs);
+			}
+		}
+	}
+
 }

Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/factory/FileSystemFactoryMgr.java

@@ -347,4 +347,12 @@ public GFileSystem probe(ByteProvider byteProvider, FileSystemService fsService,
 
 	}
 
+	/**
+	 * Returns the filesystem providers available to this factory.
+	 *
+	 * @return a copy of the available filesystem providers.
+	 */
+	public Map<String, FileSystemInfoRec> getFileSystemInfoRecs() {
+		return new HashMap<>(fsByType);
+	}
 }

Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/factory/GFileSystemProbeManual.java

@@ -0,0 +1,24 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.formats.gfilesystem.factory;
+
+/**
+ * A {@link GFileSystemProbe} interface for filesystems that can be directly
+ * chosen by the user as a fallback if automatic filesystem detection fails.
+ */
+public interface GFileSystemProbeManual extends GFileSystemProbe {
+	// Empty interface.
+}

Ghidra/Features/Base/src/main/java/ghidra/plugins/fsbrowser/FileSystemBrowserPlugin.java

@@ -16,7 +16,7 @@
 package ghidra.plugins.fsbrowser;
 
 import java.util.*;
-
+import java.util.stream.Collectors;
 import java.awt.Component;
 import java.awt.event.InputEvent;
 import java.awt.event.KeyEvent;
@@ -35,8 +35,14 @@
 import ghidra.app.events.ProgramActivatedPluginEvent;
 import ghidra.app.plugin.PluginCategoryNames;
 import ghidra.app.services.*;
+import ghidra.app.util.bin.ByteProvider;
 import ghidra.app.util.opinion.LoaderService;
 import ghidra.formats.gfilesystem.*;
+import ghidra.formats.gfilesystem.factory.FileSystemFactoryMgr;
+import ghidra.formats.gfilesystem.factory.FileSystemInfoRec;
+import ghidra.formats.gfilesystem.factory.GFileSystemProbeByteProvider;
+import ghidra.formats.gfilesystem.factory.GFileSystemProbeBytesOnly;
+import ghidra.formats.gfilesystem.factory.GFileSystemProbeManual;
 import ghidra.framework.main.FrontEndService;
 import ghidra.framework.main.ApplicationLevelPlugin;
 import ghidra.framework.model.Project;
@@ -244,9 +250,12 @@ private void doOpenFilesystem(FSRL containerFSRL, Component parent, TaskMonitor
 			FileSystemRef ref = fsService().probeFileForFilesystem(containerFSRL, monitor,
 				FileSystemProbeConflictResolver.GUI_PICKER);
 			if (ref == null) {
-				Msg.showWarn(this, parent, "Open Filesystem",
-					"No filesystem provider for " + containerFSRL.getName());
-				return;
+				ref = showFallbackFileSystemChooser(containerFSRL, parent, monitor);
+				if (ref == null) {
+					Msg.showWarn(this, parent, "Open Filesystem",
+							"No filesystem provider for " + containerFSRL.getName());
+					return;
+				}
 			}
 
 			createNewFileSystemBrowser(ref, true);
@@ -257,6 +266,42 @@ private void doOpenFilesystem(FSRL containerFSRL, Component parent, TaskMonitor
 		}
 	}
 
+	private FileSystemRef showFallbackFileSystemChooser(FSRL containerFSRL, Component parent, TaskMonitor monitor) throws CancelledException, IOException {
+		FileSystemFactoryMgr fsFactoryMgr = FileSystemFactoryMgr.getInstance();
+
+		//@formatter:off
+		List<FileSystemInfoRec> fsList = fsFactoryMgr.getFileSystemInfoRecs().values()
+				.stream()
+				.filter(fs -> fs.getFactory() instanceof GFileSystemProbeManual)
+				.sorted((filesystem1, filesystem2) -> filesystem1.getDescription().compareToIgnoreCase(filesystem2.getDescription()))
+				.collect(Collectors.toList());
+		//@formatter:on
+
+		if (fsList.isEmpty()) {
+			return null;
+		}
+
+		FileSystemInfoRec chosenFilesystem = SelectFromListDialog.selectFromList(fsList, "Select filesystem",
+				"Select a filesystem from list", FileSystemInfoRec::getDescription);
+		if (chosenFilesystem == null) {
+			return null;
+		}
+
+		ByteProvider byteProvider = fsService().getByteProvider(containerFSRL, true, monitor);
+		GFileSystem fs = fsFactoryMgr.mountFileSystem(chosenFilesystem.getType(), byteProvider, fsService, monitor);
+		if (fs != null) {
+			FileSystemRef fsRef = fsService().getMountedFilesystem(containerFSRL.makeNested(chosenFilesystem.getType()));
+			if (fsRef != null) {
+				fs.close();
+				return fsRef;
+			}
+			fsService().addFileSystem(fs);
+			return fs.getRefManager().create();
+		}
+
+		return null;
+	}
+
 	/**
 	 * Prompts the user to pick a file system container file to open using a local
 	 * filesystem browser and then displays that filesystem in a new fsb browser.