Add virtual directory feature to Tracker

Similar to stored queries, files of the virtual directory type behave
like directories -- i.e. they open in a list-mode Tracker window and
show up as an item with submenu in navigation menus. The file itself is
a plain text file in driver settings format. It can have an arbitrary
number of "directory" entries, which specify the paths of (actual)
directories for which the virtual directory provides a merged view. The
view will not show duplicate entries. For non-directory entries the
first one encountered (according to the order the directory paths are
specified in the file) will be shown. A subdirectory entry will again
behave like a virtual directory.

The support in Tracker isn't perfect yet. I'm afraid major refactoring
would be necessary to get it there.

The virtual directory file type uses a differently colored version of
the folder icon. Alternatives welcome.

src/kits/tracker/VirtualDirectoryEntryList.cpp

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2013, Haiku, Inc.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Ingo Weinhold, [email protected]
+ */
+
+
+#include "VirtualDirectoryEntryList.h"
+
+#include <AutoLocker.h>
+#include <storage_support.h>
+
+#include "Model.h"
+#include "VirtualDirectoryManager.h"
+
+
+namespace BPrivate {
+
+
+VirtualDirectoryEntryList::VirtualDirectoryEntryList(Model* model)
+	:
+	EntryListBase(),
+	fDefinitionFileRef(),
+	fMergedDirectory(BMergedDirectory::B_ALWAYS_FIRST)
+{
+	VirtualDirectoryManager* manager = VirtualDirectoryManager::Instance();
+	if (manager == NULL) {
+		fStatus = B_NO_MEMORY;
+		return;
+	}
+
+	AutoLocker<VirtualDirectoryManager> managerLocker(manager);
+	BStringList directoryPaths;
+	fStatus = manager->ResolveDirectoryPaths(*model->NodeRef(),
+		*model->EntryRef(), directoryPaths, &fDefinitionFileRef);
+	if (fStatus != B_OK)
+		return;
+
+	fStatus = _InitMergedDirectory(directoryPaths);
+}
+
+
+VirtualDirectoryEntryList::VirtualDirectoryEntryList(
+	const node_ref& definitionFileRef, const BStringList& directoryPaths)
+	:
+	EntryListBase(),
+	fDefinitionFileRef(definitionFileRef),
+	fMergedDirectory(BMergedDirectory::B_ALWAYS_FIRST)
+{
+	fStatus = _InitMergedDirectory(directoryPaths);
+}
+
+
+VirtualDirectoryEntryList::~VirtualDirectoryEntryList()
+{
+}
+
+
+status_t
+VirtualDirectoryEntryList::InitCheck() const
+{
+	return EntryListBase::InitCheck();
+}
+
+
+status_t
+VirtualDirectoryEntryList::GetNextEntry(BEntry* entry, bool traverse)
+{
+	entry_ref ref;
+	status_t error = GetNextRef(&ref);
+	if (error != B_OK)
+		return error;
+
+	return entry->SetTo(&ref, traverse);
+}
+
+
+status_t
+VirtualDirectoryEntryList::GetNextRef(entry_ref* ref)
+{
+	BPrivate::Storage::LongDirEntry entry;
+	int32 result = GetNextDirents(&entry, sizeof(entry), 1);
+	if (result < 0)
+		return result;
+	if (result == 0)
+		return B_ENTRY_NOT_FOUND;
+
+	ref->device = entry.d_pdev;
+	ref->directory = entry.d_pino;
+	return ref->set_name(entry.d_name);
+}
+
+
+int32
+VirtualDirectoryEntryList::GetNextDirents(struct dirent* buffer, size_t length,
+	int32 count)
+{
+	if (count > 1)
+		count = 1;
+
+	int32 countRead = fMergedDirectory.GetNextDirents(buffer, length, count);
+	if (countRead != 1)
+		return countRead;
+
+	// deal with directories
+	entry_ref ref;
+	ref.device = buffer->d_pdev;
+	ref.directory = buffer->d_pino;
+	if (ref.set_name(buffer->d_name) == B_OK && BEntry(&ref).IsDirectory()) {
+		if (VirtualDirectoryManager* manager
+				= VirtualDirectoryManager::Instance()) {
+			AutoLocker<VirtualDirectoryManager> managerLocker(manager);
+			manager->TranslateDirectoryEntry(fDefinitionFileRef, buffer);
+		}
+	}
+
+	return countRead;
+}
+
+
+status_t
+VirtualDirectoryEntryList::Rewind()
+{
+	return fMergedDirectory.Rewind();
+}
+
+
+int32
+VirtualDirectoryEntryList::CountEntries()
+{
+	return 0;
+}
+
+
+status_t
+VirtualDirectoryEntryList::_InitMergedDirectory(
+	const BStringList& directoryPaths)
+{
+	status_t error = fMergedDirectory.Init();
+	if (error != B_OK)
+		return error;
+
+	int32 count = directoryPaths.CountStrings();
+	for (int32 i = 0; i < count; i++)
+		fMergedDirectory.AddDirectory(directoryPaths.StringAt(i));
+
+	return B_OK;
+}
+
+
+} // namespace BPrivate