//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose: 
//
// $NoKeywords: $
//===========================================================================//

#ifndef FILESYSTEM_H
#define FILESYSTEM_H
#pragma once

#include <limits.h>

#include "tier0/threadtools.h"
#include "tier0/memalloc.h"
#include "tier1/interface.h"
#include "tier1/utlsymbol.h"
#include "tier1/utlstring.h"
#include "appframework/IAppSystem.h"
#include "tier1/checksum_crc.h"
#include "tier1/checksum_md5.h"
#include "tier1/refcount.h"

#ifdef _WIN32
#pragma once
#endif

//-----------------------------------------------------------------------------
// Forward declarations
//-----------------------------------------------------------------------------

class CUtlBuffer;
class KeyValues;
class IFileList;
class IThreadPool;
class CMemoryFileBacking;

typedef void * FileHandle_t;
typedef void * FileCacheHandle_t;
typedef int FileFindHandle_t;
typedef void (*FileSystemLoggingFunc_t)( const char *fileName, const char *accessType );
typedef int WaitForResourcesHandle_t;

#ifdef _X360
typedef void* HANDLE;
#endif

#define USE_CRC_FILE_TRACKING 0

// Turn on some extra pure server debug spew in certain builds.
// WARNING: This spew can be used by hackers to locate places to hack
// the code to bypas sv_pure!  Be careful!
#if defined( _DEBUG ) || defined( STAGING_ONLY )
	#define PURE_SERVER_DEBUG_SPEW
#endif

/// How strict will the pure server be for a particular set of files
enum EPureServerFileClass
{
	ePureServerFileClass_Unknown = -1, // dummy debugging value
	ePureServerFileClass_Any = 0,
	ePureServerFileClass_AnyTrusted,
	ePureServerFileClass_CheckHash,
};

class IPureServerWhitelist
{
public:

	// Reference counting
	virtual void AddRef() = 0;
	virtual void Release() = 0;

	// What should we do with a particular file?
	virtual EPureServerFileClass GetFileClass( const char *pszFilename ) = 0;

	// Access list of trusted keys which we will allow to set trusted content
	virtual int GetTrustedKeyCount() const = 0;
	virtual const byte *GetTrustedKey( int iKeyIndex, int *nKeySize ) const = 0;
};

//-----------------------------------------------------------------------------
// Enums used by the interface
//-----------------------------------------------------------------------------

#define FILESYSTEM_MAX_SEARCH_PATHS 128

enum FileSystemSeek_t
{
	FILESYSTEM_SEEK_HEAD	= SEEK_SET,
	FILESYSTEM_SEEK_CURRENT = SEEK_CUR,
	FILESYSTEM_SEEK_TAIL	= SEEK_END,
};

enum
{
	FILESYSTEM_INVALID_FIND_HANDLE = -1
};

enum FileWarningLevel_t
{
	// A problem!
	FILESYSTEM_WARNING = -1,

	// Don't print anything
	FILESYSTEM_WARNING_QUIET = 0,

	// On shutdown, report names of files left unclosed
	FILESYSTEM_WARNING_REPORTUNCLOSED,

	// Report number of times a file was opened, closed
	FILESYSTEM_WARNING_REPORTUSAGE,

	// Report all open/close events to console ( !slow! )
	FILESYSTEM_WARNING_REPORTALLACCESSES,

	// Report all open/close/read events to the console ( !slower! )
	FILESYSTEM_WARNING_REPORTALLACCESSES_READ,

	// Report all open/close/read/write events to the console ( !slower! )
	FILESYSTEM_WARNING_REPORTALLACCESSES_READWRITE,

	// Report all open/close/read/write events and all async I/O file events to the console ( !slower(est)! )
	FILESYSTEM_WARNING_REPORTALLACCESSES_ASYNC,

};

// search path filtering
enum PathTypeFilter_t
{
	FILTER_NONE        = 0,	// no filtering, all search path types match
	FILTER_CULLPACK    = 1,	// pack based search paths are culled (maps and zips)
	FILTER_CULLNONPACK = 2,	// non-pack based search paths are culled
};

// search path querying (bit flags)
enum
{
	PATH_IS_NORMAL      = 0x00, // normal path, not pack based
	PATH_IS_PACKFILE    = 0x01, // path is a pack file
	PATH_IS_MAPPACKFILE = 0x02, // path is a map pack file
	PATH_IS_REMOTE		= 0x04, // path is the remote filesystem
};
typedef uint32 PathTypeQuery_t;

#define IS_PACKFILE( n ) ( n & ( PATH_IS_PACKFILE | PATH_IS_MAPPACKFILE ) )
#define IS_REMOTE( n )   ( n & PATH_IS_REMOTE )

enum DVDMode_t
{
	DVDMODE_OFF    = 0, // not using dvd
	DVDMODE_STRICT = 1, // dvd device only
	DVDMODE_DEV    = 2, // dev mode, mutiple devices ok
};

// In non-retail builds, enable the file blocking access tracking stuff...
#if defined( TRACK_BLOCKING_IO )
enum FileBlockingWarning_t
{
	// Report how long synchronous i/o took to complete
	FILESYSTEM_BLOCKING_SYNCHRONOUS = 0,
	// Report how long async i/o took to complete if AsyncFileFinished caused it to load via "blocking" i/o
	FILESYSTEM_BLOCKING_ASYNCHRONOUS_BLOCK,
	// Report how long async i/o took to complete
	FILESYSTEM_BLOCKING_ASYNCHRONOUS,
	// Report how long the async "callback" took
	FILESYSTEM_BLOCKING_CALLBACKTIMING,

	FILESYSTEM_BLOCKING_NUMBINS,
};

#pragma pack(1)
class FileBlockingItem
{
public:
	enum
	{
		FB_ACCESS_OPEN = 1,
		FB_ACCESS_CLOSE = 2,
		FB_ACCESS_READ = 3,
		FB_ACCESS_WRITE = 4,
		FB_ACCESS_APPEND = 5,
		FB_ACCESS_SIZE = 6
	};

	FileBlockingItem() :
		m_ItemType( (FileBlockingWarning_t)0 ),
		m_flElapsed( 0.0f ),
		m_nAccessType( 0 )
	{
		SetFileName( NULL );
	}

	FileBlockingItem( int type, char const *filename, float elapsed, int accessType ) :
		m_ItemType( (FileBlockingWarning_t)type ),
		m_flElapsed( elapsed ),
		m_nAccessType( accessType )
	{
		SetFileName( filename );
	}

	void SetFileName( char const *filename )
	{
		if ( !filename )
		{
			m_szFilename[ 0 ] = 0;
			return;
		}

		int len = Q_strlen( filename );
		if ( len >= sizeof( m_szFilename ) )
		{
			Q_strncpy( m_szFilename, &filename[ len - sizeof( m_szFilename ) + 1 ], sizeof( m_szFilename ) );
		}
		else
		{
			Q_strncpy( m_szFilename, filename, sizeof( m_szFilename ) );
		}
	}

	char const *GetFileName() const
	{
		return m_szFilename;
	}

	FileBlockingWarning_t	m_ItemType;
	float					m_flElapsed;
	byte					m_nAccessType;
private:

	char					m_szFilename[ 32 ];
};
#pragma pack()

class IBlockingFileItemList
{
public:
	
	// You can't call any of the below calls without locking first
	virtual void	LockMutex() = 0;
	virtual void	UnlockMutex() = 0;

	virtual int		First() const = 0;
	virtual int		Next( int i ) const = 0;
	virtual int		InvalidIndex() const = 0;

	virtual const	FileBlockingItem& Get( int index ) const = 0;

	virtual void	Reset() = 0;
};

#endif // TRACK_BLOCKING_IO

enum FilesystemMountRetval_t
{
	FILESYSTEM_MOUNT_OK = 0,
	FILESYSTEM_MOUNT_FAILED,
};

enum SearchPathAdd_t
{
	PATH_ADD_TO_HEAD,		// First path searched
	PATH_ADD_TO_TAIL,		// Last path searched
};

enum FilesystemOpenExFlags_t
{
	FSOPEN_UNBUFFERED		= (1 << 0),
	FSOPEN_FORCE_TRACK_CRC	= (1 << 1),		// This makes it calculate a CRC for the file (if the file came from disk) regardless 
											// of the IFileList passed to RegisterFileWhitelist.
	FSOPEN_NEVERINPACK	    = (1 << 2),		// 360 only, hint to FS that file is not allowed to be in pack file
};

#define FILESYSTEM_INVALID_HANDLE	( FileHandle_t )0

//-----------------------------------------------------------------------------
// Structures used by the interface
//-----------------------------------------------------------------------------

struct FileSystemStatistics
{
	CInterlockedUInt	nReads,		
						nWrites,		
						nBytesRead,
						nBytesWritten,
						nSeeks;
};

//-----------------------------------------------------------------------------
// File system allocation functions. Client must free on failure
//-----------------------------------------------------------------------------
typedef void *(*FSAllocFunc_t)( const char *pszFilename, unsigned nBytes );


//-----------------------------------------------------------------------------
// Used to display dirty disk error functions
//-----------------------------------------------------------------------------
typedef void (*FSDirtyDiskReportFunc_t)();


//-----------------------------------------------------------------------------
// Asynchronous support types
//-----------------------------------------------------------------------------
DECLARE_POINTER_HANDLE(FSAsyncControl_t);
DECLARE_POINTER_HANDLE(FSAsyncFile_t);
const FSAsyncFile_t FS_INVALID_ASYNC_FILE = (FSAsyncFile_t)(0x0000ffff);


//---------------------------------------------------------
// Async file status
//---------------------------------------------------------
enum FSAsyncStatus_t
{
	FSASYNC_ERR_NOT_MINE     = -8,	// Filename not part of the specified file system, try a different one.  (Used internally to find the right filesystem)
	FSASYNC_ERR_RETRY_LATER  = -7,	// Failure for a reason that might be temporary.  You might retry, but not immediately.  (E.g. Network problems)
	FSASYNC_ERR_ALIGNMENT    = -6,	// read parameters invalid for unbuffered IO
	FSASYNC_ERR_FAILURE      = -5,	// hard subsystem failure
	FSASYNC_ERR_READING      = -4,	// read error on file
	FSASYNC_ERR_NOMEMORY     = -3,	// out of memory for file read
	FSASYNC_ERR_UNKNOWNID    = -2,	// caller's provided id is not recognized
	FSASYNC_ERR_FILEOPEN     = -1,	// filename could not be opened (bad path, not exist, etc)
	FSASYNC_OK               = 0,	// operation is successful
	FSASYNC_STATUS_PENDING,			// file is properly queued, waiting for service
	FSASYNC_STATUS_INPROGRESS,		// file is being accessed
	FSASYNC_STATUS_ABORTED,			// file was aborted by caller
	FSASYNC_STATUS_UNSERVICED,		// file is not yet queued
};

//---------------------------------------------------------
// Async request flags
//---------------------------------------------------------
enum FSAsyncFlags_t
{
	FSASYNC_FLAGS_ALLOCNOFREE		= ( 1 << 0 ),	// do the allocation for dataPtr, but don't free
	FSASYNC_FLAGS_FREEDATAPTR		= ( 1 << 1 ),	// free the memory for the dataPtr post callback
	FSASYNC_FLAGS_SYNC				= ( 1 << 2 ),	// Actually perform the operation synchronously. Used to simplify client code paths
	FSASYNC_FLAGS_NULLTERMINATE		= ( 1 << 3 ),	// allocate an extra byte and null terminate the buffer read in
};

//---------------------------------------------------------
// Return value for CheckFileCRC.
//---------------------------------------------------------
enum EFileCRCStatus
{
	k_eFileCRCStatus_CantOpenFile,		// We don't have this file. 
	k_eFileCRCStatus_GotCRC,
	k_eFileCRCStatus_FileInVPK
};

// Used in CacheFileCRCs.
enum ECacheCRCType
{
	k_eCacheCRCType_SingleFile,
	k_eCacheCRCType_Directory,
	k_eCacheCRCType_Directory_Recursive
};

//---------------------------------------------------------
// Optional completion callback for each async file serviced (or failed)
// call is not reentrant, async i/o guaranteed suspended until return
// Note: If you change the signature of the callback, you will have to account for it in FileSystemV12 (toml [4/18/2005] )
//---------------------------------------------------------
struct FileAsyncRequest_t;
typedef void (*FSAsyncCallbackFunc_t)(const FileAsyncRequest_t &request, int nBytesRead, FSAsyncStatus_t err);

//---------------------------------------------------------
// Description of an async request
//---------------------------------------------------------
struct FileAsyncRequest_t
{
	FileAsyncRequest_t()	{ memset( this, 0, sizeof(*this) ); hSpecificAsyncFile = FS_INVALID_ASYNC_FILE;	}
	const char *			pszFilename;		// file system name
	void *					pData;				// optional, system will alloc/free if NULL
	int						nOffset;			// optional initial seek_set, 0=beginning
	int						nBytes;				// optional read clamp, -1=exist test, 0=full read
	FSAsyncCallbackFunc_t	pfnCallback;		// optional completion callback
	void *					pContext;			// caller's unique file identifier
	int						priority;			// inter list priority, 0=lowest
	unsigned				flags;				// behavior modifier
	const char *			pszPathID;			// path ID (NOTE: this field is here to remain binary compatible with release HL2 filesystem interface)
	FSAsyncFile_t			hSpecificAsyncFile; // Optional hint obtained using AsyncBeginRead()
	FSAllocFunc_t			pfnAlloc;			// custom allocator. can be null. not compatible with FSASYNC_FLAGS_FREEDATAPTR
};


struct FileHash_t 
{
	enum EFileHashType_t
	{
		k_EFileHashTypeUnknown			= 0,
		k_EFileHashTypeEntireFile		= 1,
		k_EFileHashTypeIncompleteFile	= 2,
	};
	FileHash_t()
	{
		m_eFileHashType = FileHash_t::k_EFileHashTypeUnknown;
		m_cbFileLen = 0;
		m_PackFileID = 0;
		m_nPackFileNumber = 0;
	}
	int m_eFileHashType;
	CRC32_t m_crcIOSequence;
	MD5Value_t m_md5contents;
	int m_cbFileLen;
	int m_PackFileID;
	int m_nPackFileNumber;

	bool operator==( const FileHash_t &src ) const
	{
		return m_crcIOSequence == src.m_crcIOSequence && 
			m_md5contents == src.m_md5contents && 
			m_eFileHashType == src.m_eFileHashType;
	}
	bool operator!=( const FileHash_t &src ) const
	{
		return m_crcIOSequence != src.m_crcIOSequence || 
			m_md5contents != src.m_md5contents || 
			m_eFileHashType != src.m_eFileHashType;
	}

};

class CUnverifiedFileHash
{
public:
	char m_PathID[MAX_PATH];
	char m_Filename[MAX_PATH];
	int m_nFileFraction;
	FileHash_t m_FileHash;
};

class CUnverifiedCRCFile
{
public:
	char m_PathID[MAX_PATH];
	char m_Filename[MAX_PATH];
	CRC32_t m_CRC;
};

class CUnverifiedMD5File
{
public:
	char m_PathID[MAX_PATH];
	char m_Filename[MAX_PATH];
	unsigned char bits[MD5_DIGEST_LENGTH];
};

// Spew flags for SetWhitelistSpewFlags (set with the fs_whitelist_spew_flags cvar).
// Update the comment for the fs_whitelist_spew_flags cvar if you change these.
#define WHITELIST_SPEW_WHILE_LOADING		0x0001	// list files as they are added to the CRC tracker
#define WHITELIST_SPEW_RELOAD_FILES			0x0002	// show files the filesystem is telling the engine to reload
#define WHITELIST_SPEW_DONT_RELOAD_FILES	0x0004	// show files the filesystem is NOT telling the engine to reload

//-----------------------------------------------------------------------------
// Interface to fetch a file asynchronously from any source.  This is used
// as a hook
//-----------------------------------------------------------------------------

abstract_class IAsyncFileFetch {
public:
	typedef void *Handle;

	/// Initiate a request.  Returns error status, or on success
	/// returns an opaque handle used to terminate the job
	///
	/// Should return FSASYNC_ERR_NOT_MINE if the filename isn't
	/// handled by this interface
	///
	/// The callback is required, and is the only mechanism to communicate
	/// status.  (No polling.)  The request is automatically destroyed anytime
	/// after the callback is executed.
	virtual FSAsyncStatus_t Start( const FileAsyncRequest_t &request, Handle *pOutHandle, IThreadPool *pThreadPool ) = 0;

	/// Attempt to complete any active work, returning status.  The callback WILL
	/// be executed (this is necessary in case we allocated the buffer).
	/// Afterwards, the request is automatically destroyed.
	virtual FSAsyncStatus_t FinishSynchronous( Handle hControl ) = 0;

	/// Terminate any active work and destroy all resources and bookkeeping info.
	/// The callback will NOT be executed.
	virtual FSAsyncStatus_t Abort( Handle hControl ) = 0;
};

// This interface is for VPK files to communicate with FileTracker
abstract_class IThreadedFileMD5Processor
{
public:
	virtual int				SubmitThreadedMD5Request( uint8 *pubBuffer, int cubBuffer, int PackFileID, int nPackFileNumber, int nPackFileFraction ) = 0;
	virtual bool			BlockUntilMD5RequestComplete( int iRequest, MD5Value_t *pMd5ValueOut ) = 0;
	virtual bool			IsMD5RequestComplete( int iRequest, MD5Value_t *pMd5ValueOut ) = 0;
};

//-----------------------------------------------------------------------------
// Base file system interface
//-----------------------------------------------------------------------------

// This is the minimal interface that can be implemented to provide access to
// a named set of files.
#define BASEFILESYSTEM_INTERFACE_VERSION		"VBaseFileSystem011"

abstract_class IBaseFileSystem
{
public:
	virtual int				Read( void* pOutput, int size, FileHandle_t file ) = 0;
	virtual int				Write( void const* pInput, int size, FileHandle_t file ) = 0;

	// if pathID is NULL, all paths will be searched for the file
	virtual FileHandle_t	Open( const char *pFileName, const char *pOptions, const char *pathID = 0 ) = 0;
	virtual void			Close( FileHandle_t file ) = 0;


	virtual void			Seek( FileHandle_t file, int pos, FileSystemSeek_t seekType ) = 0;
	virtual unsigned int	Tell( FileHandle_t file ) = 0;
	virtual unsigned int	Size( FileHandle_t file ) = 0;
	virtual unsigned int	Size( const char *pFileName, const char *pPathID = 0 ) = 0;

	virtual void			Flush( FileHandle_t file ) = 0;
	virtual bool			Precache( const char *pFileName, const char *pPathID = 0 ) = 0;

	virtual bool			FileExists( const char *pFileName, const char *pPathID = 0 ) = 0;
	virtual bool			IsFileWritable( char const *pFileName, const char *pPathID = 0 ) = 0;
	virtual bool			SetFileWritable( char const *pFileName, bool writable, const char *pPathID = 0 ) = 0;

	virtual long			GetFileTime( const char *pFileName, const char *pPathID = 0 ) = 0;

	//--------------------------------------------------------
	// Reads/writes files to utlbuffers. Use this for optimal read performance when doing open/read/close
	//--------------------------------------------------------
	virtual bool			ReadFile( const char *pFileName, const char *pPath, CUtlBuffer &buf, int nMaxBytes = 0, int nStartingByte = 0, FSAllocFunc_t pfnAlloc = NULL ) = 0;
	virtual bool			WriteFile( const char *pFileName, const char *pPath, CUtlBuffer &buf ) = 0;
	virtual bool			UnzipFile( const char *pFileName, const char *pPath, const char *pDestination ) = 0;
};


//-----------------------------------------------------------------------------
// Main file system interface
//-----------------------------------------------------------------------------

#define FILESYSTEM_INTERFACE_VERSION			"VFileSystem022"

abstract_class IFileSystem : public IAppSystem, public IBaseFileSystem
{
public:
	//--------------------------------------------------------
	// Steam operations
	//--------------------------------------------------------

	virtual bool			IsSteam() const = 0;

	// Supplying an extra app id will mount this app in addition 
	// to the one specified in the environment variable "steamappid"
	// 
	// If nExtraAppId is < -1, then it will mount that app ID only.
	// (Was needed by the dedicated server b/c the "SteamAppId" env var only gets passed to steam.dll
	// at load time, so the dedicated couldn't pass it in that way).
	virtual	FilesystemMountRetval_t MountSteamContent( int nExtraAppId = -1 ) = 0;

	//--------------------------------------------------------
	// Search path manipulation
	//--------------------------------------------------------

	// Add paths in priority order (mod dir, game dir, ....)
	// If one or more .pak files are in the specified directory, then they are
	//  added after the file system path
	// If the path is the relative path to a .bsp file, then any previous .bsp file 
	//  override is cleared and the current .bsp is searched for an embedded PAK file
	//  and this file becomes the highest priority search path ( i.e., it's looked at first
	//   even before the mod's file system path ).
	virtual void			AddSearchPath( const char *pPath, const char *pathID, SearchPathAdd_t addType = PATH_ADD_TO_TAIL ) = 0;
	virtual bool			RemoveSearchPath( const char *pPath, const char *pathID = 0 ) = 0;

	// Remove all search paths (including write path?)
	virtual void			RemoveAllSearchPaths( void ) = 0;

	// Remove search paths associated with a given pathID
	virtual void			RemoveSearchPaths( const char *szPathID ) = 0;

	// This is for optimization. If you mark a path ID as "by request only", then files inside it
	// will only be accessed if the path ID is specifically requested. Otherwise, it will be ignored.
	// If there are currently no search paths with the specified path ID, then it will still
	// remember it in case you add search paths with this path ID.
	virtual void			MarkPathIDByRequestOnly( const char *pPathID, bool bRequestOnly ) = 0;

	// converts a partial path into a full path
	// Prefer using the RelativePathToFullPath_safe template wrapper to calling this directly
	virtual const char		*RelativePathToFullPath( const char *pFileName, const char *pPathID, OUT_Z_CAP(maxLenInChars) char *pDest, int maxLenInChars, PathTypeFilter_t pathFilter = FILTER_NONE, PathTypeQuery_t *pPathType = NULL ) = 0;
	template <size_t maxLenInChars> const char *RelativePathToFullPath_safe( const char *pFileName, const char *pPathID, OUT_Z_ARRAY char (&pDest)[maxLenInChars], PathTypeFilter_t pathFilter = FILTER_NONE, PathTypeQuery_t *pPathType = NULL )
	{
		return RelativePathToFullPath( pFileName, pPathID, pDest, (int)maxLenInChars, pathFilter, pPathType );
	}

	// Returns the search path, each path is separated by ;s. Returns the length of the string returned
	// Prefer using the GetSearchPath_safe template wrapper to calling this directly
	virtual int				GetSearchPath( const char *pathID, bool bGetPackFiles, OUT_Z_CAP(maxLenInChars) char *pDest, int maxLenInChars ) = 0;
	template <size_t maxLenInChars> int GetSearchPath_safe( const char *pathID, bool bGetPackFiles, OUT_Z_ARRAY char (&pDest)[maxLenInChars] )
	{
		return GetSearchPath( pathID, bGetPackFiles, pDest, (int)maxLenInChars );
	}

	// interface for custom pack files > 4Gb
	virtual bool			AddPackFile( const char *fullpath, const char *pathID ) = 0;

	//--------------------------------------------------------
	// File manipulation operations
	//--------------------------------------------------------

	// Deletes a file (on the WritePath)
	virtual void			RemoveFile( char const* pRelativePath, const char *pathID = 0 ) = 0;

	// Renames a file (on the WritePath)
	virtual bool			RenameFile( char const *pOldPath, char const *pNewPath, const char *pathID = 0 ) = 0;

	// create a local directory structure
	virtual void			CreateDirHierarchy( const char *path, const char *pathID = 0 ) = 0;

	// File I/O and info
	virtual bool			IsDirectory( const char *pFileName, const char *pathID = 0 ) = 0;

	virtual void			FileTimeToString( char* pStrip, int maxCharsIncludingTerminator, long fileTime ) = 0;

	//--------------------------------------------------------
	// Open file operations
	//--------------------------------------------------------

	virtual void			SetBufferSize( FileHandle_t file, unsigned nBytes ) = 0;

	virtual bool			IsOk( FileHandle_t file ) = 0;

	virtual bool			EndOfFile( FileHandle_t file ) = 0;

	virtual char			*ReadLine( char *pOutput, int maxChars, FileHandle_t file ) = 0;
	virtual int				FPrintf( FileHandle_t file, PRINTF_FORMAT_STRING const char *pFormat, ... ) = 0;

	//--------------------------------------------------------
	// Dynamic library operations
	//--------------------------------------------------------

	// load/unload modules
	virtual CSysModule 		*LoadModule( const char *pFileName, const char *pPathID = 0, bool bValidatedDllOnly = true ) = 0;
	virtual void			UnloadModule( CSysModule *pModule ) = 0;

	//--------------------------------------------------------
	// File searching operations
	//--------------------------------------------------------

	// FindFirst/FindNext. Also see FindFirstEx.
	virtual const char		*FindFirst( const char *pWildCard, FileFindHandle_t *pHandle ) = 0;
	virtual const char		*FindNext( FileFindHandle_t handle ) = 0;
	virtual bool			FindIsDirectory( FileFindHandle_t handle ) = 0;
	virtual void			FindClose( FileFindHandle_t handle ) = 0;

	// Same as FindFirst, but you can filter by path ID, which can make it faster.
	virtual const char		*FindFirstEx( 
		const char *pWildCard, 
		const char *pPathID,
		FileFindHandle_t *pHandle
		) = 0;

	//--------------------------------------------------------
	// File name and directory operations
	//--------------------------------------------------------

	// FIXME: This method is obsolete! Use RelativePathToFullPath instead!
	// converts a partial path into a full path
	// Prefer using the GetLocalPath_safe template wrapper to calling this directly
	virtual const char		*GetLocalPath( const char *pFileName, OUT_Z_CAP(maxLenInChars) char *pDest, int maxLenInChars ) = 0;
	template <size_t maxLenInChars> const char *GetLocalPath_safe( const char *pFileName, OUT_Z_ARRAY char (&pDest)[maxLenInChars] )
	{
		return GetLocalPath( pFileName, pDest, (int)maxLenInChars );
	}

	// Returns true on success ( based on current list of search paths, otherwise false if 
	//  it can't be resolved )
	// Prefer using the FullPathToRelativePath_safe template wrapper to calling this directly
	virtual bool			FullPathToRelativePath( const char *pFullpath, OUT_Z_CAP(maxLenInChars) char *pDest, int maxLenInChars ) = 0;
	template <size_t maxLenInChars> bool FullPathToRelativePath_safe( const char *pFullpath, OUT_Z_ARRAY char (&pDest)[maxLenInChars] )
	{
		return FullPathToRelativePath( pFullpath, pDest, (int)maxLenInChars );
	}

	// Gets the current working directory
	virtual bool			GetCurrentDirectory( char* pDirectory, int maxlen ) = 0;

	//--------------------------------------------------------
	// Filename dictionary operations
	//--------------------------------------------------------

	virtual FileNameHandle_t	FindOrAddFileName( char const *pFileName ) = 0;
	virtual bool				String( const FileNameHandle_t& handle, char *buf, int buflen ) = 0;

	//--------------------------------------------------------
	// Asynchronous file operations
	//--------------------------------------------------------

	//------------------------------------
	// Global operations
	//------------------------------------
			FSAsyncStatus_t	AsyncRead( const FileAsyncRequest_t &request, FSAsyncControl_t *phControl = NULL )	{ return AsyncReadMultiple( &request, 1, phControl ); 	}
	virtual FSAsyncStatus_t	AsyncReadMultiple( const FileAsyncRequest_t *pRequests, int nRequests,  FSAsyncControl_t *phControls = NULL ) = 0;
	virtual FSAsyncStatus_t	AsyncAppend(const char *pFileName, const void *pSrc, int nSrcBytes, bool bFreeMemory, FSAsyncControl_t *pControl = NULL ) = 0;
	virtual FSAsyncStatus_t	AsyncAppendFile(const char *pAppendToFileName, const char *pAppendFromFileName, FSAsyncControl_t *pControl = NULL ) = 0;
	virtual void			AsyncFinishAll( int iToPriority = 0 ) = 0;
	virtual void			AsyncFinishAllWrites() = 0;
	virtual FSAsyncStatus_t	AsyncFlush() = 0;
	virtual bool			AsyncSuspend() = 0;
	virtual bool			AsyncResume() = 0;

	/// Add async fetcher interface.  This gives apps a hook to intercept async requests and
	/// pull the data from a source of their choosing.  The immediate use case is to load
	/// assets from the CDN via HTTP.
	virtual void AsyncAddFetcher( IAsyncFileFetch *pFetcher ) = 0;
	virtual void AsyncRemoveFetcher( IAsyncFileFetch *pFetcher ) = 0;

	//------------------------------------
	// Functions to hold a file open if planning on doing mutiple reads. Use is optional,
	// and is taken only as a hint
	//------------------------------------
	virtual FSAsyncStatus_t	AsyncBeginRead( const char *pszFile, FSAsyncFile_t *phFile ) = 0;
	virtual FSAsyncStatus_t	AsyncEndRead( FSAsyncFile_t hFile ) = 0;

	//------------------------------------
	// Request management
	//------------------------------------
	virtual FSAsyncStatus_t	AsyncFinish( FSAsyncControl_t hControl, bool wait = true ) = 0;
	virtual FSAsyncStatus_t	AsyncGetResult( FSAsyncControl_t hControl, void **ppData, int *pSize ) = 0;
	virtual FSAsyncStatus_t	AsyncAbort( FSAsyncControl_t hControl ) = 0;
	virtual FSAsyncStatus_t	AsyncStatus( FSAsyncControl_t hControl ) = 0;
	// set a new priority for a file already in the queue
	virtual FSAsyncStatus_t	AsyncSetPriority(FSAsyncControl_t hControl, int newPriority) = 0;
	virtual void			AsyncAddRef( FSAsyncControl_t hControl ) = 0;
	virtual void			AsyncRelease( FSAsyncControl_t hControl ) = 0;

	//--------------------------------------------------------
	// Remote resource management
	//--------------------------------------------------------

	// starts waiting for resources to be available
	// returns FILESYSTEM_INVALID_HANDLE if there is nothing to wait on
	virtual WaitForResourcesHandle_t WaitForResources( const char *resourcelist ) = 0;
	// get progress on waiting for resources; progress is a float [0, 1], complete is true on the waiting being done
	// returns false if no progress is available
	// any calls after complete is true or on an invalid handle will return false, 0.0f, true
	virtual bool			GetWaitForResourcesProgress( WaitForResourcesHandle_t handle, float *progress /* out */ , bool *complete /* out */ ) = 0;
	// cancels a progress call
	virtual void			CancelWaitForResources( WaitForResourcesHandle_t handle ) = 0;

	// hints that a set of files will be loaded in near future
	// HintResourceNeed() is not to be confused with resource precaching.
	virtual int				HintResourceNeed( const char *hintlist, int forgetEverything ) = 0;
	// returns true if a file is on disk
	virtual bool			IsFileImmediatelyAvailable(const char *pFileName) = 0;
	
	// copies file out of pak/bsp/steam cache onto disk (to be accessible by third-party code)
	virtual void			GetLocalCopy( const char *pFileName ) = 0;

	//--------------------------------------------------------
	// Debugging operations
	//--------------------------------------------------------

	// Dump to printf/OutputDebugString the list of files that have not been closed
	virtual void			PrintOpenedFiles( void ) = 0;
	virtual void			PrintSearchPaths( void ) = 0;

	// output
	virtual void			SetWarningFunc( void (*pfnWarning)( PRINTF_FORMAT_STRING const char *fmt, ... ) ) = 0;
	virtual void			SetWarningLevel( FileWarningLevel_t level ) = 0;
	virtual void			AddLoggingFunc( void (*pfnLogFunc)( const char *fileName, const char *accessType ) ) = 0;
	virtual void			RemoveLoggingFunc( FileSystemLoggingFunc_t logFunc ) = 0;

	// Returns the file system statistics retreived by the implementation.  Returns NULL if not supported.
	virtual const FileSystemStatistics *GetFilesystemStatistics() = 0;

	//--------------------------------------------------------
	// Start of new functions after Lost Coast release (7/05)
	//--------------------------------------------------------

	virtual FileHandle_t	OpenEx( const char *pFileName, const char *pOptions, unsigned flags = 0, const char *pathID = 0, char **ppszResolvedFilename = NULL ) = 0;

	// Extended version of read provides more context to allow for more optimal reading
	virtual int				ReadEx( void* pOutput, int sizeDest, int size, FileHandle_t file ) = 0;
	virtual int				ReadFileEx( const char *pFileName, const char *pPath, void **ppBuf, bool bNullTerminate = false, bool bOptimalAlloc = false, int nMaxBytes = 0, int nStartingByte = 0, FSAllocFunc_t pfnAlloc = NULL ) = 0;

	virtual FileNameHandle_t	FindFileName( char const *pFileName ) = 0;

#if defined( TRACK_BLOCKING_IO )
	virtual void			EnableBlockingFileAccessTracking( bool state ) = 0;
	virtual bool			IsBlockingFileAccessEnabled() const = 0;

	virtual IBlockingFileItemList *RetrieveBlockingFileAccessInfo() = 0;
#endif

	virtual void SetupPreloadData() = 0;
	virtual void DiscardPreloadData() = 0;

	// Fixme, we could do these via a string embedded into the compiled data, etc...
	enum KeyValuesPreloadType_t
	{
		TYPE_VMT,
		TYPE_SOUNDEMITTER,
		TYPE_SOUNDSCAPE,
		NUM_PRELOAD_TYPES
	};

	virtual void		LoadCompiledKeyValues( KeyValuesPreloadType_t type, char const *archiveFile ) = 0;

	// If the "PreloadedData" hasn't been purged, then this'll try and instance the KeyValues using the fast path of compiled keyvalues loaded during startup.
	// Otherwise, it'll just fall through to the regular KeyValues loading routines
	virtual KeyValues	*LoadKeyValues( KeyValuesPreloadType_t type, char const *filename, char const *pPathID = 0 ) = 0;
	virtual bool		LoadKeyValues( KeyValues& head, KeyValuesPreloadType_t type, char const *filename, char const *pPathID = 0 ) = 0;
	virtual bool		ExtractRootKeyName( KeyValuesPreloadType_t type, char *outbuf, size_t bufsize, char const *filename, char const *pPathID = 0 ) = 0;

	virtual FSAsyncStatus_t	AsyncWrite(const char *pFileName, const void *pSrc, int nSrcBytes, bool bFreeMemory, bool bAppend = false, FSAsyncControl_t *pControl = NULL ) = 0;
	virtual FSAsyncStatus_t	AsyncWriteFile(const char *pFileName, const CUtlBuffer *pSrc, int nSrcBytes, bool bFreeMemory, bool bAppend = false, FSAsyncControl_t *pControl = NULL ) = 0;
	// Async read functions with memory blame
	FSAsyncStatus_t			AsyncReadCreditAlloc( const FileAsyncRequest_t &request, const char *pszFile, int line, FSAsyncControl_t *phControl = NULL )	{ return AsyncReadMultipleCreditAlloc( &request, 1, pszFile, line, phControl ); 	}
	virtual FSAsyncStatus_t	AsyncReadMultipleCreditAlloc( const FileAsyncRequest_t *pRequests, int nRequests, const char *pszFile, int line, FSAsyncControl_t *phControls = NULL ) = 0;

	virtual bool			GetFileTypeForFullPath( char const *pFullPath, OUT_Z_BYTECAP(bufSizeInBytes) wchar_t *buf, size_t bufSizeInBytes ) = 0;

	//--------------------------------------------------------
	//--------------------------------------------------------
	virtual bool		ReadToBuffer( FileHandle_t hFile, CUtlBuffer &buf, int nMaxBytes = 0, FSAllocFunc_t pfnAlloc = NULL ) = 0;

	//--------------------------------------------------------
	// Optimal IO operations
	//--------------------------------------------------------
	virtual bool		GetOptimalIOConstraints( FileHandle_t hFile, unsigned *pOffsetAlign, unsigned *pSizeAlign, unsigned *pBufferAlign ) = 0;
	inline unsigned		GetOptimalReadSize( FileHandle_t hFile, unsigned nLogicalSize );
	virtual void		*AllocOptimalReadBuffer( FileHandle_t hFile, unsigned nSize = 0, unsigned nOffset = 0 ) = 0;
	virtual void		FreeOptimalReadBuffer( void * ) = 0;

	//--------------------------------------------------------
	//
	//--------------------------------------------------------
	virtual void		BeginMapAccess() = 0;
	virtual void		EndMapAccess() = 0;

	// Returns true on success, otherwise false if it can't be resolved
	// Prefer using the FullPathToRelativePathEx_safe template wrapper to calling this directly
	virtual bool		FullPathToRelativePathEx( const char *pFullpath, const char *pPathId, OUT_Z_CAP(maxLenInChars) char *pDest, int maxLenInChars ) = 0;
	template <size_t maxLenInChars> bool FullPathToRelativePathEx_safe( const char *pFullpath, OUT_Z_ARRAY char (&pDest)[maxLenInChars] )
	{
		return FullPathToRelativePathEx( pFullpath, pDest, (int)maxLenInChars );
	}

	virtual int			GetPathIndex( const FileNameHandle_t &handle ) = 0;
	virtual long		GetPathTime( const char *pPath, const char *pPathID ) = 0;

	virtual DVDMode_t	GetDVDMode() = 0;

	//--------------------------------------------------------
	// Whitelisting for pure servers.
	//--------------------------------------------------------

	// This should be called ONCE at startup. Multiplayer games (gameinfo.txt does not contain singleplayer_only)
	// want to enable this so sv_pure works.
	virtual void			EnableWhitelistFileTracking( bool bEnable, bool bCacheAllVPKHashes, bool bRecalculateAndCheckHashes ) = 0;

	// This is called when the client connects to a server using a pure_server_whitelist.txt file.
	virtual void			RegisterFileWhitelist( IPureServerWhitelist *pWhiteList, IFileList **pFilesToReload ) = 0;

	// Called when the client logs onto a server. Any files that came off disk should be marked as 
	// unverified because this server may have a different set of files it wants to guarantee.
	virtual void			MarkAllCRCsUnverified() = 0;

	// As the server loads whitelists when it transitions maps, it calls this to calculate CRCs for any files marked
	// with check_crc.   Then it calls CheckCachedFileCRC later when it gets client requests to verify CRCs.
	virtual void			CacheFileCRCs( const char *pPathname, ECacheCRCType eType, IFileList *pFilter ) = 0;
	virtual EFileCRCStatus	CheckCachedFileHash( const char *pPathID, const char *pRelativeFilename, int nFileFraction, FileHash_t *pFileHash ) = 0;

	// Fills in the list of files that have been loaded off disk and have not been verified.
	// Returns the number of files filled in (between 0 and nMaxFiles).
	//
	// This also removes any files it's returning from the unverified CRC list, so they won't be
	// returned from here again.
	// The client sends batches of these to the server to verify.
	virtual int				GetUnverifiedFileHashes( CUnverifiedFileHash *pFiles, int nMaxFiles ) = 0;
	
	// Control debug message output.
	// Pass a combination of WHITELIST_SPEW_ flags.
	virtual int				GetWhitelistSpewFlags() = 0;
	virtual void			SetWhitelistSpewFlags( int flags ) = 0;

	// Installs a callback used to display a dirty disk dialog
	virtual void			InstallDirtyDiskReportFunc( FSDirtyDiskReportFunc_t func ) = 0;

	//--------------------------------------------------------
	// Low-level file caching. Cached files are loaded into memory and used
	// to satisfy read requests (sync and async) until the cache is destroyed.
	// NOTE: this could defeat file whitelisting, if a file were loaded in
	// a non-whitelisted environment and then reused. Clients should not cache
	// files across moves between pure/non-pure environments.
	//--------------------------------------------------------
	virtual FileCacheHandle_t CreateFileCache() = 0;
	virtual void AddFilesToFileCache( FileCacheHandle_t cacheId, const char **ppFileNames, int nFileNames, const char *pPathID ) = 0;
	virtual bool IsFileCacheFileLoaded( FileCacheHandle_t cacheId, const char* pFileName ) = 0;
	virtual bool IsFileCacheLoaded( FileCacheHandle_t cacheId ) = 0;
	virtual void DestroyFileCache( FileCacheHandle_t cacheId ) = 0;

	// XXX For now, we assume that all path IDs are "GAME", never cache files
	// outside of the game search path, and preferentially return those files
	// whenever anyone searches for a match even if an on-disk file in another
	// folder would have been found first in a traditional search. extending
	// the memory cache to cover non-game files isn't necessary right now, but
	// should just be a matter of defining a more complex key type. (henryg)

	// Register a CMemoryFileBacking; must balance with UnregisterMemoryFile.
	// Returns false and outputs an ref-bumped pointer to the existing entry
	// if the same file has already been registered by someone else; this must
	// be Unregistered to maintain the balance.
	virtual bool RegisterMemoryFile( CMemoryFileBacking *pFile, CMemoryFileBacking **ppExistingFileWithRef ) = 0;

	// Unregister a CMemoryFileBacking; must balance with RegisterMemoryFile.
	virtual void UnregisterMemoryFile( CMemoryFileBacking *pFile ) = 0;

	virtual void			CacheAllVPKFileHashes( bool bCacheAllVPKHashes, bool bRecalculateAndCheckHashes ) = 0;
	virtual bool			CheckVPKFileHash( int PackFileID, int nPackFileNumber, int nFileFraction, MD5Value_t &md5Value ) = 0;

	// Called when we unload a file, to remove that file's info for pure server purposes.
	virtual void			NotifyFileUnloaded( const char *pszFilename, const char *pPathId ) = 0;

	// Returns true on successfully retrieve case-sensitive full path, otherwise false
	// Prefer using the GetCaseCorrectFullPath template wrapper to calling this directly
	virtual bool			GetCaseCorrectFullPath_Ptr( const char *pFullPath, OUT_Z_CAP( maxLenInChars ) char *pDest, int maxLenInChars ) = 0;
	template <size_t maxLenInChars> bool GetCaseCorrectFullPath( const char *pFullPath, OUT_Z_ARRAY char( &pDest )[maxLenInChars] )
	{
		return GetCaseCorrectFullPath_Ptr( pFullPath, pDest, (int)maxLenInChars );
	}
};

//-----------------------------------------------------------------------------
// Memory file backing, which you can use to fake out the filesystem, caching data
// in memory and have it associated with a file
//-----------------------------------------------------------------------------
class CMemoryFileBacking : public CRefCounted<CRefCountServiceMT>
{
public:
	// malloc and free in headers with our janky memdbg system. What could go wrong. Except everything.
	// (this free can't skip memdbg if paired malloc used memdbg)
#include <memdbgon.h>
	CMemoryFileBacking( IFileSystem* pFS ) : m_pFS( pFS ), m_nRegistered( 0 ), m_pFileName( NULL ), m_pData( NULL ), m_nLength( 0 ) { }
	~CMemoryFileBacking() { free( (char*) m_pFileName ); if ( m_pData ) m_pFS->FreeOptimalReadBuffer( (char*) m_pData ); }
#include <memdbgoff.h>

	IFileSystem* m_pFS;
	int m_nRegistered;
	const char* m_pFileName;
	const char* m_pData;
	int m_nLength;

private:
	CMemoryFileBacking( const CMemoryFileBacking& ); // not defined
	CMemoryFileBacking& operator=( const CMemoryFileBacking& ); // not defined
};

//-----------------------------------------------------------------------------

#if defined( _X360 ) && !defined( _RETAIL )
extern char g_szXboxProfileLastFileOpened[MAX_PATH];
#define SetLastProfileFileRead( s ) Q_strncpy( g_szXboxProfileLastFileOpened, sizeof( g_szXboxProfileLastFileOpened), pFileName )
#define GetLastProfileFileRead() (&g_szXboxProfileLastFileOpened[0])
#else
#define SetLastProfileFileRead( s ) ((void)0)
#define GetLastProfileFileRead() NULL
#endif

#if defined( _X360 ) && defined( _BASETSD_H_ )
class CXboxDiskCacheSetter
{
public:
	CXboxDiskCacheSetter( SIZE_T newSize )
	{
		m_oldSize = XGetFileCacheSize();
		XSetFileCacheSize( newSize );
	}

	~CXboxDiskCacheSetter()
	{
		XSetFileCacheSize( m_oldSize );
	}
private:
	SIZE_T m_oldSize;
};
#define DISK_INTENSIVE() CXboxDiskCacheSetter cacheSetter( 1024*1024 )
#else
#define DISK_INTENSIVE() ((void)0)
#endif

//-----------------------------------------------------------------------------

inline unsigned IFileSystem::GetOptimalReadSize( FileHandle_t hFile, unsigned nLogicalSize ) 
{ 
	unsigned align; 
	if ( GetOptimalIOConstraints( hFile, &align, NULL, NULL ) ) 
		return AlignValue( nLogicalSize, align );
	else
		return nLogicalSize;
}

//-----------------------------------------------------------------------------

// We include this here so it'll catch compile errors in VMPI early.
#include "filesystem_passthru.h"

//-----------------------------------------------------------------------------
// Async memory tracking
//-----------------------------------------------------------------------------

#if (defined(_DEBUG) || defined(USE_MEM_DEBUG))
#define AsyncRead( a, b ) AsyncReadCreditAlloc( a, __FILE__, __LINE__, b )
#define AsyncReadMutiple( a, b, c ) AsyncReadMultipleCreditAlloc( a, b, __FILE__, __LINE__, c )
#endif

extern IFileSystem *g_pFullFileSystem;

#endif // FILESYSTEM_H