Refactor where architecture selection is performed for universal binaries

Responsibility for selecting an architecture is moved out of
`UniversalTransform` and into a new `ContainerOpenRequest` class.
`UniversalTransform` still handles architecture selection in headless
operation (for now).

4 files changed, 57 insertions, 5 deletions

diff --git a/ui/containerbrowser.h b/ui/containerbrowser.h
index 363e5446..b9ba278f 100644
--- a/ui/containerbrowser.h
+++ b/ui/containerbrowser.h
@@ -15,6 +15,7 @@
 
 #include <vector>
 
+class ContainerOpenRequest;
 
 class ContainerTreeModel : public QAbstractItemModel
 {
@@ -121,4 +122,8 @@ public:
 	bool openWithOptionsRequested() const { return m_openWithOptionsRequested; }
 
 	static std::vector<TransformContextRef> openContainerFile(const QString& path, bool forceShowDialog = false, bool* outOpenWithOptions = nullptr);
+
+	// Show the container browser dialog for the given open request.
+	// Returns the selected contexts, or empty if the user cancelled.
+	static std::vector<TransformContextRef> showBrowser(ContainerOpenRequest& request, bool* outOpenWithOptions = nullptr);
 };
diff --git a/ui/containeropenrequest.h b/ui/containeropenrequest.h
new file mode 100644
index 00000000..55d8923e
--- /dev/null
+++ b/ui/containeropenrequest.h
@@ -0,0 +1,46 @@
+#pragma once
+
+#include "uitypes.h"
+
+#include <optional>
+#include <string>
+#include <vector>
+
+
+// Captures user settings and intent for opening a container file, and provides
+// policy decisions (e.g. whether to show the container browser) after processing.
+class BINARYNINJAUIAPI ContainerOpenRequest
+{
+public:
+	enum Action {
+		Cancel,
+		AutoOpen,
+		BrowseContainer,
+	};
+
+	explicit ContainerOpenRequest(const std::string& path, bool forceContainerBrowser = false);
+
+	TransformSessionRef session() const { return m_session; }
+
+	// Create the session, process it, and determine what action the caller
+	// should take. Returns Cancel if the session could not be created.
+	Action resolve();
+
+	// Get the default selection from a processed session. If no selection has
+	// been made (e.g. because the session auto-opened), selects the current leaf.
+	std::vector<TransformContextRef> selectedContexts();
+
+	// When the container is a universal binary, the available architectures and the
+	// index of the preferred one (if any).
+	const std::vector<TransformContextRef>& architectureContexts() const { return m_archContexts; }
+	std::optional<size_t> preferredArchitectureIndex() const { return m_preferredArch; }
+
+private:
+	Action resolveUniversal(TransformContextRef universalCtx);
+
+	TransformSessionRef m_session;
+	std::vector<TransformContextRef> m_archContexts;
+	std::optional<size_t> m_preferredArch;
+	bool m_forceContainerBrowser = false;
+	bool m_autoOpen = false;
+};
diff --git a/view/macho/universaltransform.cpp b/view/macho/universaltransform.cpp
index 3309d853..33164215 100644
--- a/view/macho/universaltransform.cpp
+++ b/view/macho/universaltransform.cpp
@@ -266,19 +266,20 @@ bool UniversalTransform::DecodeWithContext(Ref<TransformContext> context, const
 			architectures.push_back(archName);
 		}
 
-		if (!context->IsInteractive())
+		// TODO: It is surprising that this is UniversalTransform's responsibility.
+		if (!BinaryNinja::IsUIEnabled())
 		{
+			// When headless, filter to the preferred architecture if one is configured.
 			vector<string> archPref = context->GetSettings()->Get<vector<string>>("files.universal.architecturePreference");
 			if (auto result = find_first_of(archPref.begin(), archPref.end(), architectures.begin(), architectures.end()); result != archPref.end())
 			{
-				// Filter to preferred architecture to support container auto-open policy
 				size_t archIndex = find(architectures.begin(), architectures.end(), *result) - architectures.begin();
 				context->SetAvailableFiles({architectures[archIndex]});
 				return false;
 			}
 
-			// Preserve original headless load behavior when no architecturePreference is specified
-			if (!BinaryNinja::IsUIEnabled() && archPref.empty() && architectures.size())
+			// Load the first architecture if no preference is found.
+			if (archPref.empty() && architectures.size())
 			{
 				context->SetAvailableFiles({architectures[0]});
 				return false;
diff --git a/view/macho/universalview.cpp b/view/macho/universalview.cpp
index 16e973f5..bd8fc7ef 100644
--- a/view/macho/universalview.cpp
+++ b/view/macho/universalview.cpp
@@ -30,7 +30,7 @@ void BinaryNinja::InitUniversalViewType()
 			"type" : "array",
 			"sorted" : false,
 			"default" : [],
-			"description" : "Specify an architecture preference for automatic loading of a Mach-O file from a Universal archive. When unset, headless operation defaults to the first available architecture, while interactive operation presents all available architectures for selection.",
+			"description" : "Architectures to prefer when loading Universal (fat) Mach-O archives, in order of priority. Determines which architecture is pre-selected in the architecture picker, or loaded automatically when prompting is set to 'automatic' or 'never'.",
 			"ignore" : ["SettingsProjectScope", "SettingsResourceScope"]
 			})");