Add basic infrastructure for file handler plugins.

The purpose of this is for games which use archive file formats
(containing many individual files), so that assets, files, etc. can be
worked on more rapidly.

Core/FileSystems/VirtualDiscFileSystem.cpp

@@ -94,7 +94,8 @@ void VirtualDiscFileSystem::LoadFileListIndex() {
 		// Check if there's a handler specified.
 		size_t handler_pos = line.find(':', filename_pos);
 		if (handler_pos != line.npos) {
-			entry.fileName = line.substr(filename_pos + 1, handler_pos - filename_pos);
+			entry.fileName = line.substr(filename_pos + 1, handler_pos - filename_pos - 1);
+			NOTICE_LOG(HLE, "Handler found: %s", line.substr(handler_pos + 1).c_str());
 			// TODO: Implement handler.
 		} else {
 			entry.fileName = line.substr(filename_pos + 1);
@@ -637,3 +638,11 @@ bool VirtualDiscFileSystem::RemoveFile(const std::string &filename)
 	ERROR_LOG(HLE,"VirtualDiscFileSystem: Cannot remove file on virtual disc");
 	return false;
 }
+
+VirtualDiscFileSystem::Handler::Handler(const char *filename) {
+	// TODO
+}
+
+VirtualDiscFileSystem::Handler::~Handler() {
+	// TODO
+}

Core/FileSystems/VirtualDiscFileSystem.h

@@ -24,8 +24,7 @@
 #include "Core/FileSystems/FileSystem.h"
 #include "Core/FileSystems/DirectoryFileSystem.h"
 
-class VirtualDiscFileSystem: public IFileSystem
+class VirtualDiscFileSystem: public IFileSystem {
-{
 public:
 	VirtualDiscFileSystem(IHandleAllocator *_hAlloc, std::string _basePath);
 	~VirtualDiscFileSystem();
@@ -53,10 +52,51 @@ private:
 	int getFileListIndex(u32 accessBlock, u32 accessSize, bool blockMode = false);
 	std::string GetLocalPath(std::string localpath);
 
+	typedef void *HandlerLibrary;
+	typedef int HandlerHandle;
+	typedef s64 HandlerOffset;
+	typedef void (*HandlerLogFunc)(HandlerHandle fd, int level, const char *msg);
+
+	// The primary purpose of handlers is to make it easier to work with large archives.
+	// However, they have other uses as well, such as patching individual files.
+	struct Handler {
+		Handler(const char *filename);
+		~Handler();
+
+		HandlerLibrary library;
+		bool (*Init)(HandlerLogFunc logger);
+		void (*Shutdown)();
+		HandlerHandle (*Open)(const char *basePath, const char *filename);
+		HandlerOffset (*Seek)(HandlerHandle handle, HandlerOffset offset, FileMove origin);
+		HandlerOffset (*Read)(HandlerHandle handle, void *data, HandlerOffset size);
+		void (*Close)(HandlerHandle handle);
+	};
+
+	struct HandlerFileHandle {
+		Handler *handler;
+		HandlerHandle handle;
+
+		bool Open(std::string& basePath, std::string& fileName, FileAccess access) {
+			// Ignore access, read only.
+			handle = handler->Open(basePath.c_str(), fileName.c_str());
+			return handle > 0;
+		}
+		size_t Read(u8 *data, s64 size) {
+			return (size_t)handler->Read(handle, data, size);
+		}
+		size_t Seek(s32 position, FileMove type) {
+			return (size_t)handler->Seek(handle, position, type);
+		}
+		void Close() {
+			handler->Close(handle);
+		}
+	};
+
 	typedef enum { VFILETYPE_NORMAL, VFILETYPE_LBN, VFILETYPE_ISO } VirtualFileType;
 
 	struct OpenFileEntry {
 		DirectoryFileHandle hFile;
+		HandlerFileHandle handler;
 		VirtualFileType type;
 		u32 fileIndex;
 		u32 curOffset;
@@ -77,4 +117,6 @@ private:
 
 	std::vector<FileListEntry> fileList;
 	u32 currentBlockIndex;
+
+	std::map<std::string, Handler> handlers;
 };