cnq3/code/qcommon/files.cpp

/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.

Quake III Arena source code is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

#include "q_shared.h"
#include "qcommon.h"
#include "unzip.h"

/*
=============================================================================

QUAKE3 FILESYSTEM

All of Quake's data access is through a hierarchical file system, but the contents of
the file system can be transparently merged from several sources.

A "qpath" is a reference to game file data.  MAX_ZPATH is 256 characters, which must include
a terminating zero. "..", "\\", and ":" are explicitly illegal in qpaths to prevent any
references outside the quake directory system.

The "base path" is the path to the directory holding all the game directories and usually
the executable.  It defaults to ".", but can be overridden with a "+set fs_basepath c:\quake3"
command line to allow code debugging in a different directory.  Basepath cannot
be modified at all after startup.  Any files that are created (demos, screenshots,
etc) will be created reletive to the base path, so base path should usually be writable.

If a user runs the game directly from a CD, the base path would be on the CD.  This
should still function correctly, but all file writes will fail (harmlessly).

The "home path" is the path used for all write access. On win32 systems we have "base path"
== "home path", but on *nix systems the base installation is usually readonly, and
"home path" points to ~/.q3a or similar

The user can also install custom mods and content in "home path", so it should be searched
along with "home path" and "cd path" for game content.


The "base game" is the directory under the paths where data comes from by default, and
can be either "baseq3" or "demoq3".

The "current game" may be the same as the base game, or it may be the name of another
directory under the paths that should be searched for files before looking in the base game.
This is the basis for addons.

Clients automatically set the game directory after receiving a gamestate from a server,
so only servers need to worry about +set fs_game.

No other directories outside of the base game and current game will ever be referenced by
filesystem functions.

To save disk space and speed loading, directory trees can be collapsed into zip files.
The files use a ".pk3" extension to prevent users from unzipping them accidentally, but
otherwise the are simply normal uncompressed zip files.  A game directory can have multiple
zip files of the form "pak0.pk3", "pak1.pk3", etc.  Zip files are searched in decending order
from the highest number to the lowest, and will always take precedence over the filesystem.
This allows a pk3 distributed as a patch to override all existing data.

Because we will have updated executables freely available online, there is no point to
trying to restrict demo / oem versions of the game with code changes.  Demo / oem versions
should be exactly the same executables as release versions, but with different data that
automatically restricts where game media can come from to prevent add-ons from working.

If not running in restricted mode, and a file is not found in any local filesystem,
an attempt will be made to download it and save it under the base path.

File search order: when FS_FOpenFileRead gets called it will go through the fs_searchpaths
structure and stop on the first successful hit. fs_searchpaths is built with successive
calls to FS_AddGameDirectory

Additionaly, we search in several subdirectories:
current game is the current mode
base game is a variable to allow mods based on other mods
(such as baseq3 + missionpack content combination in a mod for instance)
BASEGAME is the hardcoded base game ("baseq3")

e.g. the qpath "sound/newstuff/test.wav" would be searched for in the following places:

home path + current game's zip files
home path + current game's directory
base path + current game's zip files
base path + current game's directory
cd path + current game's zip files
cd path + current game's directory

home path + base game's zip file
home path + base game's directory
base path + base game's zip file
base path + base game's directory
cd path + base game's zip file
cd path + base game's directory

home path + BASEGAME's zip file
home path + BASEGAME's directory
base path + BASEGAME's zip file
base path + BASEGAME's directory
cd path + BASEGAME's zip file
cd path + BASEGAME's directory

server download, to be written to home path + current game's directory


The filesystem can be safely shutdown and reinitialized with different
basedir / cddir / game combinations, but all other subsystems that rely on it
(sound, video) must also be forced to restart.

Because the same files are loaded by both the clip model (CM_) and renderer (TR_)
subsystems, a simple single-file caching scheme is used.  The CM_ subsystems will
load the file with a request to cache.  Only one file will be kept cached at a time,
so any models that are going to be referenced by both subsystems should alternate
between the CM_ load function and the ref load function.

TODO: A qpath that starts with a leading slash will always refer to the base game, even if another
game is currently active.  This allows character models, skins, and sounds to be downloaded
to a common directory no matter which game is active.

How to prevent downloading zip files?
Pass pk3 file names in systeminfo, and download before FS_Restart()?

Aborting a download disconnects the client from the server.

How to mark files as downloadable?  Commercial add-ons won't be downloadable.

Non-commercial downloads will want to download the entire zip file.
the game would have to be reset to actually read the zip in

Auto-update information

Path separators

Casing

  separate server gamedir and client gamedir, so if the user starts
  a local game after having connected to a network game, it won't stick
  with the network game.

  allow menu options for game selection?

Read / write config to floppy option.

Different version coexistance?

When building a pak file, make sure a q3config.cfg isn't present in it,
or configs will never get loaded from disk!

  todo:

  downloading (outside fs?)
  game directory passing and restarting

=============================================================================

*/


#define MAX_ZPATH			256
#define	MAX_SEARCH_PATHS	4096
#define MAX_FILEHASH_SIZE	1024

typedef struct fileInPack_s {
	char					*name;		// name of the file
	unsigned long			pos;		// file info position in zip
	struct fileInPack_s*	next;		// next file in the hash
} fileInPack_t;

typedef struct {
	char			pakFilename[MAX_OSPATH];	// c:\quake3\baseq3\pak0.pk3
	char			pakBasename[MAX_OSPATH];	// pak0
	char			pakGamename[MAX_OSPATH];	// baseq3
	unzFile			handle;						// handle to zip file
	int				checksum;					// regular checksum
	int				pure_checksum;				// checksum for pure
	int				numfiles;					// number of files in pk3
	int				referenced;					// referenced file flags
	int				hashSize;					// hash table size (power of 2)
	fileInPack_t*	*hashTable;					// hash table
	fileInPack_t*	buildBuffer;				// buffer with the filenames etc.
} pack_t;

typedef struct {
	char		path[MAX_OSPATH];		// c:\quake3
	char		gamedir[MAX_OSPATH];	// baseq3
} directory_t;

typedef struct searchpath_s {
	struct searchpath_s *next;
	pack_t		*pack;		// only one of pack / dir will be non-NULL
	directory_t	*dir;
} searchpath_t;

static char fs_gamedir[MAX_OSPATH]; // this will be a single file name with no separators
static cvar_t* fs_debug;
static cvar_t* fs_homepath;
static cvar_t* fs_basepath;
static cvar_t* fs_basegame;
static cvar_t* fs_gamedirvar;
static searchpath_t* fs_searchpaths;

static int fs_readCount;	// total bytes read
static int fs_loadCount;	// total files read
static int fs_loadStack;	// total files in memory
static int fs_packFiles;	// total number of files in packs

static int fs_checksumFeed;

typedef union {
	FILE*		o;
	unzFile		z;
} qfile_gut;

typedef struct {
	qfile_gut	file;
	qbool		unique;
} qfile_ut;

typedef struct {
	qfile_ut	handleFiles;
	qbool		handleSync;
	int			baseOffset;
	int			fileSize;
	int			zipFilePos;
	qbool		zipFile;
	char		name[MAX_ZPATH];
} fileHandleData_t;

static fileHandleData_t fsh[MAX_FILE_HANDLES];

// TTimo - https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=540
// whether we did a reorder on the current search path when joining the server
static qbool fs_reordered;

// never load anything from pk3 files that are not present at the server when pure
static int		fs_numServerPaks;								// only non-zero when *connected to* a pure server
static int		fs_serverPaks[MAX_SEARCH_PATHS];				// checksums

// only used for autodownload, to make sure the client has at least
// all the pk3 files that are referenced at the server side
static int		fs_numServerReferencedPaks;
static int		fs_serverReferencedPaks[MAX_SEARCH_PATHS];			// checksums
static char		*fs_serverReferencedPakNames[MAX_SEARCH_PATHS];		// pk3 names

// last valid game folder used
static char lastValidBase[MAX_OSPATH];
static char lastValidGame[MAX_OSPATH];

#ifdef FS_MISSING
static FILE* missingFiles = NULL;
#endif


int Q_FileHash( const char* s, int tablesize )
{
	int ch, hash = 0;

	for (int i = 0; s[i]; ++i) {
		ch = tolower(s[i]);
		if (ch == '.')
			break;			// don't include extension
		if (ch =='\\')
			ch = '/';		// damn path names
		hash += ch * (i+119);
	}

	return (hash & (tablesize-1));
}


qbool FS_Initialized()
{
	return (fs_searchpaths != NULL);
}


int FS_LoadStack()
{
	return fs_loadStack;
}


static qbool FS_PakIsPure( const pack_t* pack )
{
	if (!fs_numServerPaks)
		return qtrue;

	for ( int i = 0; i < fs_numServerPaks; ++i ) {
		// FIXME: also use hashed file names
		// NOTE TTimo: a pk3 with same checksum but different name would be validated too
		//   I don't see this as allowing for any exploit, it would only happen if the client does manips of it's file names 'not a bug'
		if ( pack->checksum == fs_serverPaks[i] ) {
			return qtrue;		// on the approved list
		}
	}

	return qfalse;	// not on the pure server pak list
}


static fileHandle_t FS_HandleForFile()
{
	for ( int i = 1; i < MAX_FILE_HANDLES; ++i ) {
		if ( fsh[i].handleFiles.file.o == NULL ) {
			return i;
		}
	}

	Com_Error( ERR_DROP, "FS_HandleForFile: none free" );
	return 0;
}


static FILE* FS_FileForHandle( fileHandle_t f )
{
	if ( f < 0 || f > MAX_FILE_HANDLES ) {
		Com_Error( ERR_DROP, "FS_FileForHandle: out of reange" );
	}
	if (fsh[f].zipFile == qtrue) {
		Com_Error( ERR_DROP, "FS_FileForHandle: can't get FILE on zip file" );
	}
	if ( ! fsh[f].handleFiles.file.o ) {
		Com_Error( ERR_DROP, "FS_FileForHandle: NULL" );
	}

	return fsh[f].handleFiles.file.o;
}


void FS_ForceFlush( fileHandle_t f )
{
	FILE* file = FS_FileForHandle(f);
	setvbuf( file, NULL, _IONBF, 0 );
}


/*
================
FS_filelength

If this is called on a non-unique FILE (from a pak file),
it will return the size of the pak file, not the expected
size of the file.
================
*/
int FS_filelength( fileHandle_t f ) {
	int		pos;
	int		end;
	FILE*	h;

	h = FS_FileForHandle(f);
	pos = ftell (h);
	fseek (h, 0, SEEK_END);
	end = ftell (h);
	fseek (h, pos, SEEK_SET);

	return end;
}

/*
====================
FS_ReplaceSeparators

Fix things up differently for win/unix/mac
====================
*/
static void FS_ReplaceSeparators( char *path ) {
	char	*s;

	for ( s = path ; *s ; s++ ) {
		if ( *s == '/' || *s == '\\' ) {
			*s = PATH_SEP;
		}
	}
}

/*
===================
FS_BuildOSPath

Qpath may have either forward or backwards slashes
===================
*/
char *FS_BuildOSPath( const char *base, const char *game, const char *qpath ) {
	char	temp[MAX_OSPATH];
	static char ospath[2][MAX_OSPATH];
	static int toggle;
	
	toggle ^= 1;		// flip-flop to allow two returns without clash

	if( !game || !game[0] ) {
		game = fs_gamedir;
	}

	Com_sprintf( temp, sizeof(temp), "/%s/%s", game, qpath );
	FS_ReplaceSeparators( temp );	
	Com_sprintf( ospath[toggle], sizeof( ospath[0] ), "%s%s", base, temp );
	
	return ospath[toggle];
}


// creates any directories needed to store the given filename

static qbool FS_CreatePath( char* OSPath )
{
	
	// make absolutely sure that it can't back up the path
	// FIXME: is c: allowed???
	if ( strstr( OSPath, ".." ) || strstr( OSPath, "::" ) ) {
		Com_Printf( "WARNING: refusing to create relative path \"%s\"\n", OSPath );
		return qfalse;
	}

	char* ofs;
	for (ofs = OSPath+1 ; *ofs ; ofs++) {
		if (*ofs == PATH_SEP) {
			// create the directory
			*ofs = 0;
			Sys_Mkdir( OSPath );
			*ofs = PATH_SEP;
		}
	}

	return qtrue;
}


/*
===========
FS_Remove

===========
*/
void FS_Remove( const char *osPath ) {
	remove( osPath );
}

/*
===========
FS_HomeRemove

===========
*/
void FS_HomeRemove( const char *homePath ) {
	remove( FS_BuildOSPath( fs_homepath->string,
			fs_gamedir, homePath ) );
}

/*
================
FS_FileExists

Tests if the file exists in the current gamedir, this DOES NOT
search the paths.  This is to determine if opening a file to write
(which always goes into the current gamedir) will cause any overwrites.
NOTE TTimo: this goes with FS_FOpenFileWrite for opening the file afterwards
================
*/
qbool FS_FileExists( const char* file )
{
	return FS_FileExistsEx( file, qtrue );
}

qbool FS_FileExistsEx( const char* file, qbool curGameDir )
{
	const char* testpath = FS_BuildOSPath( fs_homepath->string, curGameDir ? fs_gamedir : "baseq3", file );
	FILE* f = fopen( testpath, "rb" );
	if (f) {
		fclose( f );
		return qtrue;
	}
	return qfalse;
}

/*
================
FS_SV_FileExists

Tests if the file exists 
================
*/
static qbool FS_SV_FileExists( const char *file )
{
	FILE *f;
	char *testpath;

	testpath = FS_BuildOSPath( fs_homepath->string, file, "");
	testpath[strlen(testpath)-1] = '\0';

	f = fopen( testpath, "rb" );
	if (f) {
		fclose( f );
		return qtrue;
	}
	return qfalse;
}


/*
===========
FS_SV_FOpenFileWrite

===========
*/
fileHandle_t FS_SV_FOpenFileWrite( const char *filename ) {
	char *ospath;
	fileHandle_t	f;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	ospath = FS_BuildOSPath( fs_homepath->string, filename, "" );
	ospath[strlen(ospath)-1] = '\0';

	f = FS_HandleForFile();
	fsh[f].zipFile = qfalse;

	if ( fs_debug->integer ) {
		Com_Printf( "FS_SV_FOpenFileWrite: %s\n", ospath );
	}

	if (!FS_CreatePath( ospath )) {
		return 0;
	}

	Com_DPrintf( "writing to: %s\n", ospath );
	fsh[f].handleFiles.file.o = fopen( ospath, "wb" );

	Q_strncpyz( fsh[f].name, filename, sizeof( fsh[f].name ) );

	fsh[f].handleSync = qfalse;
	if (!fsh[f].handleFiles.file.o) {
		f = 0;
	}
	return f;
}

static void FS_PreventSoundStutter()
{
#ifndef DEDICATED
	S_ClearSoundBuffer();
#endif
}

/*
===========
FS_SV_FOpenFileRead
search for a file somewhere below the home path, base path or cd path
we search in that order, matching FS_SV_FOpenFileRead order
===========
*/
int FS_SV_FOpenFileRead( const char *filename, fileHandle_t *fp )
{
	char *ospath;
	fileHandle_t f = 0;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	f = FS_HandleForFile();
	fsh[f].zipFile = qfalse;

	Q_strncpyz( fsh[f].name, filename, sizeof( fsh[f].name ) );

	FS_PreventSoundStutter();

  // search homepath
	ospath = FS_BuildOSPath( fs_homepath->string, filename, "" );
	// remove trailing slash
	ospath[strlen(ospath)-1] = '\0';

	if ( fs_debug->integer ) {
		Com_Printf( "FS_SV_FOpenFileRead (fs_homepath): %s\n", ospath );
	}

	fsh[f].handleFiles.file.o = fopen( ospath, "rb" );
	fsh[f].handleSync = qfalse;

  if (!fsh[f].handleFiles.file.o)
  {
    // NOTE TTimo on non *nix systems, fs_homepath == fs_basepath, might want to avoid
    if (Q_stricmp(fs_homepath->string,fs_basepath->string))
    {
      // search basepath
      ospath = FS_BuildOSPath( fs_basepath->string, filename, "" );
      ospath[strlen(ospath)-1] = '\0';

      if ( fs_debug->integer )
      {
        Com_Printf( "FS_SV_FOpenFileRead (fs_basepath): %s\n", ospath );
      }

      fsh[f].handleFiles.file.o = fopen( ospath, "rb" );
      fsh[f].handleSync = qfalse;

      if ( !fsh[f].handleFiles.file.o )
      {
        f = 0;
      }
    }
  }

	if (fsh[f].handleFiles.file.o) {
		*fp = f;
		return FS_filelength(f);
	}

	*fp = 0;
	return 0;
}


/*
===========
FS_SV_Rename

===========
*/
void FS_SV_Rename( const char *from, const char *to ) {
	char			*from_ospath, *to_ospath;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	FS_PreventSoundStutter();

	from_ospath = FS_BuildOSPath( fs_homepath->string, from, "" );
	to_ospath = FS_BuildOSPath( fs_homepath->string, to, "" );
	from_ospath[strlen(from_ospath)-1] = '\0';
	to_ospath[strlen(to_ospath)-1] = '\0';

	if ( fs_debug->integer ) {
		Com_Printf( "FS_SV_Rename: %s --> %s\n", from_ospath, to_ospath );
	}

	if (rename( from_ospath, to_ospath )) {
		// Failed, try copying it and deleting the original
		//FS_CopyFile( from_ospath, to_ospath );
		//FS_Remove( from_ospath );
		Com_Error( ERR_FATAL, "FS_SV_Rename: %s --> %s failed\n", from_ospath, to_ospath );
	}
}


/*
===========
FS_Rename

===========
*/
void FS_Rename( const char *from, const char *to ) {
	char			*from_ospath, *to_ospath;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	FS_PreventSoundStutter();

	from_ospath = FS_BuildOSPath( fs_homepath->string, fs_gamedir, from );
	to_ospath = FS_BuildOSPath( fs_homepath->string, fs_gamedir, to );

	if ( fs_debug->integer ) {
		Com_Printf( "FS_Rename: %s --> %s\n", from_ospath, to_ospath );
	}

	rename( from_ospath, to_ospath );
}

/*
==============
FS_FCloseFile

If the FILE pointer is an open pak file, leave it open.

For some reason, other dll's can't just cal fclose()
on files returned by FS_FOpenFile...
==============
*/
void FS_FCloseFile( fileHandle_t f ) {
	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if (fsh[f].zipFile == qtrue) {
		unzCloseCurrentFile( fsh[f].handleFiles.file.z );
		if ( fsh[f].handleFiles.unique ) {
			unzClose( fsh[f].handleFiles.file.z );
		}
		Com_Memset( &fsh[f], 0, sizeof( fsh[f] ) );
		return;
	}

	// we didn't find it as a pak, so close it as a unique file
	if (fsh[f].handleFiles.file.o) {
		fclose (fsh[f].handleFiles.file.o);
	}
	Com_Memset( &fsh[f], 0, sizeof( fsh[f] ) );
}

/*
===========
FS_FOpenFileWrite

===========
*/
fileHandle_t FS_FOpenFileWrite( const char *filename ) {
	char			*ospath;
	fileHandle_t	f;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	f = FS_HandleForFile();
	fsh[f].zipFile = qfalse;

	ospath = FS_BuildOSPath( fs_homepath->string, fs_gamedir, filename );

	if ( fs_debug->integer ) {
		Com_Printf( "FS_FOpenFileWrite: %s\n", ospath );
	}

	if (!FS_CreatePath( ospath )) {
		return 0;
	}

	// enabling the following line causes a recursive function call loop
	// when running with +set logfile 1 +set developer 1
	//Com_DPrintf( "writing to: %s\n", ospath );
	fsh[f].handleFiles.file.o = fopen( ospath, "wb" );

	Q_strncpyz( fsh[f].name, filename, sizeof( fsh[f].name ) );

	fsh[f].handleSync = qfalse;
	if (!fsh[f].handleFiles.file.o) {
		f = 0;
	}
	return f;
}

/*
===========
FS_FOpenFileAppend

===========
*/
fileHandle_t FS_FOpenFileAppend( const char *filename ) {
	char			*ospath;
	fileHandle_t	f;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	f = FS_HandleForFile();
	fsh[f].zipFile = qfalse;

	Q_strncpyz( fsh[f].name, filename, sizeof( fsh[f].name ) );

	FS_PreventSoundStutter();

	ospath = FS_BuildOSPath( fs_homepath->string, fs_gamedir, filename );

	if ( fs_debug->integer ) {
		Com_Printf( "FS_FOpenFileAppend: %s\n", ospath );
	}

	if (!FS_CreatePath( ospath )) {
		return 0;
	}

	fsh[f].handleFiles.file.o = fopen( ospath, "ab" );
	fsh[f].handleSync = qfalse;
	if (!fsh[f].handleFiles.file.o) {
		f = 0;
	}
	return f;
}

/*
===========
FS_FilenameCompare

Ignore case and seprator char distinctions
===========
*/
qbool FS_FilenameCompare( const char *s1, const char *s2 ) {
	int		c1, c2;

	do {
		c1 = *s1++;
		c2 = *s2++;

		if (c1 >= 'a' && c1 <= 'z') {
			c1 -= ('a' - 'A');
		}
		if (c2 >= 'a' && c2 <= 'z') {
			c2 -= ('a' - 'A');
		}

		if ( c1 == '\\' || c1 == ':' ) {
			c1 = '/';
		}
		if ( c2 == '\\' || c2 == ':' ) {
			c2 = '/';
		}

		if (c1 != c2) {
			return qtrue;		// strings not equal
		}
	} while (c1);

	return qfalse;		// strings are equal
}


// returns qtrue if we allow opening the file on the real file system

static qbool FS_IsPureClientReadException( const char* filename )
{
	const int l = strlen( filename );
	if ( l < 5 )
		return qfalse;

	const char* const s4 = filename + l - 4;
	const char* const s5 = filename + l - 5;
	return	!Q_stricmp( s4, ".cfg" ) ||
			!Q_stricmp( s4, ".ttf" ) ||
			!Q_stricmp( s4, ".dat" ) ||
			!Q_stricmp( s4, ".jpg" ) ||
			!Q_stricmp( s4, ".tga" ) ||
			!Q_stricmp( s4, ".png" ) ||
			!Q_stricmp( s5, ".jpeg" );
}


/*
===========
FS_FOpenFileRead

Finds the file in the search path.
Returns filesize and an open FILE pointer.
Used for streaming data out of either a
separate file or a ZIP file.
===========
*/
extern qbool		com_fullyInitialized;

int FS_FOpenFileRead( const char *filename, fileHandle_t *file, qbool uniqueFILE ) {
	searchpath_t	*search;
	char			*netpath;
	pack_t			*pak;
	fileInPack_t	*pakFile;
	directory_t		*dir;
	long			hash;
	unz_s			*zfi;
	FILE			*temp;
	int				l;
	char			demoExt[16];

	hash = 0;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( file == NULL ) {
		// just wants to see if file is there
		for ( search = fs_searchpaths ; search ; search = search->next ) {
			//
			if ( search->pack ) {
				hash = Q_FileHash( filename, search->pack->hashSize );
			}
			// is the element a pak file?
			if ( search->pack && search->pack->hashTable[hash] ) {
				// look through all the pak file elements
				pak = search->pack;
				pakFile = pak->hashTable[hash];
				do {
					// case and separator insensitive comparisons
					if ( !FS_FilenameCompare( pakFile->name, filename ) ) {
						// found it!
						return qtrue;
					}
					pakFile = pakFile->next;
				} while(pakFile != NULL);
			} else if ( search->dir ) {
				dir = search->dir;
				netpath = FS_BuildOSPath( dir->path, dir->gamedir, filename );
				temp = fopen (netpath, "rb");
				if ( !temp ) {
					continue;
				}
				fclose(temp);
				return qtrue;
			}
		}
		return qfalse;
	}

	if ( !filename ) {
		Com_Error( ERR_FATAL, "FS_FOpenFileRead: NULL 'filename' parameter passed\n" );
	}

	Com_sprintf (demoExt, sizeof(demoExt), ".dm_%d",PROTOCOL_VERSION );
	// qpaths are not supposed to have a leading slash
	if ( filename[0] == '/' || filename[0] == '\\' ) {
		filename++;
	}

	// make absolutely sure that it can't back up the path.
	// The searchpaths do guarantee that something will always
	// be prepended, so we don't need to worry about "c:" or "//limbo" 
	if ( strstr( filename, ".." ) || strstr( filename, "::" ) ) {
		*file = 0;
		return -1;
	}

	// make sure the q3key file is only readable by the quake3.exe at initialization
	// any other time the key should only be accessed in memory using the provided functions
	if( com_fullyInitialized && strstr( filename, "q3key" ) ) {
		*file = 0;
		return -1;
	}

	//
	// search through the path, one element at a time
	//

	*file = FS_HandleForFile();
	fsh[*file].handleFiles.unique = uniqueFILE;

	for ( search = fs_searchpaths ; search ; search = search->next ) {
		//
		if ( search->pack ) {
			hash = Q_FileHash( filename, search->pack->hashSize );
		}
		// is the element a pak file?
		if ( search->pack && search->pack->hashTable[hash] ) {
			// disregard if it doesn't match one of the allowed pure pak files
			if ( !FS_PakIsPure(search->pack) ) {
				continue;
			}

			// look through all the pak file elements
			pak = search->pack;
			pakFile = pak->hashTable[hash];
			do {
				// case and separator insensitive comparisons
				if ( !FS_FilenameCompare( pakFile->name, filename ) ) {
					// found it!

					// mark the pak as having been referenced and mark specifics on cgame and ui
					// shaders, txt, arena files  by themselves do not count as a reference as 
					// these are loaded from all pk3s 
					// from every pk3 file.. 
					l = strlen( filename );
					if ( !(pak->referenced & FS_GENERAL_REF)) {
						if ( Q_stricmp(filename + l - 7, ".shader") != 0 &&
							Q_stricmp(filename + l - 4, ".txt") != 0 &&
							Q_stricmp(filename + l - 4, ".cfg") != 0 &&
							Q_stricmp(filename + l - 7, ".config") != 0 &&
							strstr(filename, "levelshots") == NULL &&
							Q_stricmp(filename + l - 4, ".bot") != 0 &&
							Q_stricmp(filename + l - 6, ".arena") != 0 &&
							Q_stricmp(filename + l - 5, ".menu") != 0) {
							pak->referenced |= FS_GENERAL_REF;
						}
					}

					if (!(pak->referenced & FS_QAGAME_REF) && !Q_stricmp(filename, "vm/qagame.qvm")) {
						pak->referenced |= FS_QAGAME_REF;
					}
					if (!(pak->referenced & FS_CGAME_REF) && !Q_stricmp(filename, "vm/cgame.qvm")) {
						pak->referenced |= FS_CGAME_REF;
					}
					if (!(pak->referenced & FS_UI_REF) && !Q_stricmp(filename, "vm/ui.qvm")) {
						pak->referenced |= FS_UI_REF;
					}

					if ( uniqueFILE ) {
						// open a new file on the pakfile
						fsh[*file].handleFiles.file.z = unzReOpen (pak->pakFilename, pak->handle);
						if (fsh[*file].handleFiles.file.z == NULL) {
							Com_Error (ERR_FATAL, "Couldn't reopen %s", pak->pakFilename);
						}
					} else {
						fsh[*file].handleFiles.file.z = pak->handle;
					}
					Q_strncpyz( fsh[*file].name, filename, sizeof( fsh[*file].name ) );
					fsh[*file].zipFile = qtrue;
					zfi = (unz_s *)fsh[*file].handleFiles.file.z;
					// in case the file was new
					temp = zfi->file;
					// set the file position in the zip file (also sets the current file info)
					unzSetCurrentFileInfoPosition(pak->handle, pakFile->pos);
					// copy the file info into the unzip structure
					Com_Memcpy( zfi, pak->handle, sizeof(unz_s) );
					// we copy this back into the structure
					zfi->file = temp;
					// open the file in the zip
					unzOpenCurrentFile( fsh[*file].handleFiles.file.z );
					fsh[*file].zipFilePos = pakFile->pos;

					if ( fs_debug->integer ) {
						Com_Printf( "FS_FOpenFileRead: %s (found in '%s')\n", 
							filename, pak->pakFilename );
					}
					return zfi->cur_file_info.uncompressed_size;
				}
				pakFile = pakFile->next;
			} while(pakFile != NULL);
		} else if ( search->dir ) {
			// check a file in the directory tree

			// For mods, we ignore baseq3/q3config.cfg and baseq3/autoexec.cfg
			// to avoid config pollution.
			// Mod authors should package a proper default.cfg (pretty much binds only)
			// in their .pk3 so that it overrides baseq3/default.cfg (it's in pak0.pk3).
			if (	Q_stricmp( search->dir->gamedir, fs_gamedir ) &&
					(	!Q_stricmp( filename, "q3config.cfg" ) ||
						!Q_stricmp( filename, "autoexec.cfg" ) ) ) {
				continue;
			}

			// if we are running restricted, the only files we
			// will allow to come from the directory are .cfg files

      // FIXME TTimo I'm not sure about the fs_numServerPaks test
      // if you are using FS_ReadFile to find out if a file exists,
      //   this test can make the search fail although the file is in the directory
      // I had the problem on https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=8
      // turned out I used FS_FileExists instead
			if ( fs_numServerPaks && !FS_IsPureClientReadException( filename ) ) {
				continue;
			}

			dir = search->dir;
			
			netpath = FS_BuildOSPath( dir->path, dir->gamedir, filename );
			fsh[*file].handleFiles.file.o = fopen (netpath, "rb");
			if ( !fsh[*file].handleFiles.file.o ) {
				continue;
			}

			Q_strncpyz( fsh[*file].name, filename, sizeof( fsh[*file].name ) );
			fsh[*file].zipFile = qfalse;
			if ( fs_debug->integer ) {
				Com_Printf( "FS_FOpenFileRead: %s (found in '%s/%s')\n", filename,
					dir->path, dir->gamedir );
			}

			return FS_filelength (*file);
		}
	}

	Com_DPrintf ("Can't find %s\n", filename);
#ifdef FS_MISSING
	if (missingFiles) {
		fprintf(missingFiles, "%s\n", filename);
	}
#endif
	*file = 0;
	return -1;
}


/*
=================
FS_Read

Properly handles partial reads
=================
*/
int FS_Read2( void *buffer, int len, fileHandle_t f ) {
	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !f ) {
		return 0;
	}

	return FS_Read( buffer, len, f);
}

int FS_Read( void *buffer, int len, fileHandle_t f ) {
	int		block, remaining;
	int		read;
	byte	*buf;
	int		tries;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !f ) {
		return 0;
	}

	buf = (byte *)buffer;
	fs_readCount += len;

	if (fsh[f].zipFile == qfalse) {
		remaining = len;
		tries = 0;
		while (remaining) {
			block = remaining;
			read = fread (buf, 1, block, fsh[f].handleFiles.file.o);
			if (read == 0) {
				// we might have been trying to read from a CD, which
				// sometimes returns a 0 read on windows
				if (!tries) {
					tries = 1;
				} else {
					return len-remaining;	//Com_Error (ERR_FATAL, "FS_Read: 0 bytes read");
				}
			}

			if (read == -1) {
				Com_Error (ERR_FATAL, "FS_Read: -1 bytes read");
			}

			remaining -= read;
			buf += read;
		}
		return len;
	} else {
		return unzReadCurrentFile(fsh[f].handleFiles.file.z, buffer, len);
	}
}

/*
=================
FS_Write

Properly handles partial writes
=================
*/
int FS_Write( const void *buffer, int len, fileHandle_t h ) {
	int		block, remaining;
	int		written;
	byte	*buf;
	int		tries;
	FILE	*f;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !h ) {
		return 0;
	}

	f = FS_FileForHandle(h);
	buf = (byte *)buffer;

	remaining = len;
	tries = 0;
	while (remaining) {
		block = remaining;
		written = fwrite (buf, 1, block, f);
		if (written == 0) {
			if (!tries) {
				tries = 1;
			} else {
				Com_Printf( "FS_Write: 0 bytes written\n" );
				return 0;
			}
		}

		if (written == -1) {
			Com_Printf( "FS_Write: -1 bytes written\n" );
			return 0;
		}

		remaining -= written;
		buf += written;
	}
	if ( fsh[h].handleSync ) {
		fflush( f );
	}
	return len;
}

void QDECL FS_Printf( fileHandle_t h, const char *fmt, ... ) {
	va_list		argptr;
	char		msg[MAXPRINTMSG];

	va_start (argptr,fmt);
	Q_vsnprintf (msg, sizeof(msg), fmt, argptr);
	va_end (argptr);

	FS_Write(msg, strlen(msg), h);
}


#define PK3_SEEK_BUFFER_SIZE 65536

int FS_Seek( fileHandle_t f, long offset, int origin )
{
	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
		return -1;
	}

	if (fsh[f].zipFile == qtrue) {
		//FIXME: this is incomplete and really, really
		//crappy (but better than what was here before)
		byte	buffer[PK3_SEEK_BUFFER_SIZE];
		int		remainder = offset;

		if( offset < 0 || origin == FS_SEEK_END ) {
			Com_Error( ERR_FATAL, "Negative offsets and FS_SEEK_END not implemented "
					"for FS_Seek on pk3 file contents\n" );
			return -1;
		}

		switch( origin ) {
			case FS_SEEK_SET:
				unzSetCurrentFileInfoPosition(fsh[f].handleFiles.file.z, fsh[f].zipFilePos);
				unzOpenCurrentFile(fsh[f].handleFiles.file.z);
				//fallthrough

			case FS_SEEK_CUR:
				while( remainder > PK3_SEEK_BUFFER_SIZE ) {
					FS_Read( buffer, PK3_SEEK_BUFFER_SIZE, f );
					remainder -= PK3_SEEK_BUFFER_SIZE;
				}
				FS_Read( buffer, remainder, f );
				return offset;
				break;

			default:
				Com_Error( ERR_FATAL, "Bad origin in FS_Seek\n" );
				return -1;
				break;
		}
	}


	FILE* file = FS_FileForHandle(f);
	int _origin;

	switch ( origin ) {
	case FS_SEEK_CUR:
		_origin = SEEK_CUR;
		break;
	case FS_SEEK_END:
		_origin = SEEK_END;
		break;
	case FS_SEEK_SET:
		_origin = SEEK_SET;
		break;
	default:
		_origin = SEEK_CUR;
		Com_Error( ERR_FATAL, "Bad origin in FS_Seek\n" );
		break;
	}

	return fseek( file, offset, _origin );
}


/*
======================================================================================

CONVENIENCE FUNCTIONS FOR ENTIRE FILES

======================================================================================
*/


qbool FS_FileIsInPAK( const char* filename, int* pureChecksum, int* checksum )
{
	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !filename ) {
		Com_Error( ERR_FATAL, "FS_FOpenFileRead: NULL 'filename' parameter passed\n" );
	}

	// qpaths are not supposed to have a leading slash
	if ( filename[0] == '/' || filename[0] == '\\' ) {
		filename++;
	}

	// make absolutely sure that it can't back up the path.
	// The searchpaths do guarantee that something will always
	// be prepended, so we don't need to worry about "c:" or "//limbo" 
	if ( strstr( filename, ".." ) || strstr( filename, "::" ) ) {
		return qfalse;
	}

	// search through the path, one element at a time

	for ( const searchpath_t* search = fs_searchpaths; search; search = search->next ) {
		if ( !search->pack )
			continue;

		long hash = Q_FileHash( filename, search->pack->hashSize );
		// is the element a pak file?
		if ( search->pack->hashTable[hash] ) {
			// disregard if it doesn't match one of the allowed pure pak files
			if ( !FS_PakIsPure(search->pack) ) {
				continue;
			}

			// look through all the pak file elements
			const fileInPack_t* pakFile = search->pack->hashTable[hash];
			do {
				// case and separator insensitive comparisons
				if ( !FS_FilenameCompare( pakFile->name, filename ) ) {
					if (pureChecksum) {
						*pureChecksum = search->pack->pure_checksum;
					}
					if (checksum) {
						*checksum = search->pack->checksum;
					}
					return qtrue;
				}
				pakFile = pakFile->next;
			} while (pakFile);
		}
	}

	return qfalse;
}


/*
============
FS_ReadFile

Filename are relative to the quake search path
a null buffer will just return the file length without loading
============
*/
int FS_ReadFile( const char *qpath, void **buffer ) {
	fileHandle_t	h;
	byte*			buf;
	qbool		isConfig;
	int				len;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !qpath || !qpath[0] ) {
		Com_Error( ERR_FATAL, "FS_ReadFile with empty name\n" );
	}

	buf = NULL;	// quiet compiler warning

	// if this is a .cfg file and we are playing back a journal, read
	// it from the journal file
	if ( strstr( qpath, ".cfg" ) ) {
		isConfig = qtrue;
		if ( com_journal && com_journal->integer == 2 ) {
			int		r;

			Com_DPrintf( "Loading %s from journal file.\n", qpath );
			r = FS_Read( &len, sizeof( len ), com_journalDataFile );
			if ( r != sizeof( len ) ) {
				if (buffer != NULL) *buffer = NULL;
				return -1;
			}
			// if the file didn't exist when the journal was created
			if (!len) {
				if (buffer == NULL) {
					return 1;			// hack for old journal files
				}
				*buffer = NULL;
				return -1;
			}
			if (buffer == NULL) {
				return len;
			}

			buf = (byte*)Hunk_AllocateTempMemory(len+1);
			*buffer = buf;

			r = FS_Read( buf, len, com_journalDataFile );
			if ( r != len ) {
				Com_Error( ERR_FATAL, "Read from journalDataFile failed" );
			}

			fs_loadCount++;
			fs_loadStack++;

			// guarantee that it will have a trailing 0 for string operations
			buf[len] = 0;

			return len;
		}
	} else {
		isConfig = qfalse;
	}

	// look for it in the filesystem or pack files
	len = FS_FOpenFileRead( qpath, &h, qfalse );
	if ( h == 0 ) {
		if ( buffer ) {
			*buffer = NULL;
		}
		// if we are journalling and it is a config file, write a zero to the journal file
		if ( isConfig && com_journal && com_journal->integer == 1 ) {
			Com_DPrintf( "Writing zero for %s to journal file.\n", qpath );
			len = 0;
			FS_Write( &len, sizeof( len ), com_journalDataFile );
			FS_Flush( com_journalDataFile );
		}
		return -1;
	}
	
	if ( !buffer ) {
		if ( isConfig && com_journal && com_journal->integer == 1 ) {
			Com_DPrintf( "Writing len for %s to journal file.\n", qpath );
			FS_Write( &len, sizeof( len ), com_journalDataFile );
			FS_Flush( com_journalDataFile );
		}
		FS_FCloseFile( h);
		return len;
	}

	fs_loadCount++;
	fs_loadStack++;

	buf = (byte*)Hunk_AllocateTempMemory(len+1);
	*buffer = buf;

	FS_Read (buf, len, h);

	// guarantee that it will have a trailing 0 for string operations
	buf[len] = 0;
	FS_FCloseFile( h );

	// if we are journalling and it is a config file, write it to the journal file
	if ( isConfig && com_journal && com_journal->integer == 1 ) {
		Com_DPrintf( "Writing %s to journal file.\n", qpath );
		FS_Write( &len, sizeof( len ), com_journalDataFile );
		FS_Write( buf, len, com_journalDataFile );
		FS_Flush( com_journalDataFile );
	}
	return len;
}

/*
=============
FS_FreeFile
=============
*/
void FS_FreeFile( void *buffer ) {
	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}
	if ( !buffer ) {
		Com_Error( ERR_FATAL, "FS_FreeFile( NULL )" );
	}
	fs_loadStack--;

	Hunk_FreeTempMemory( buffer );

	// if all of our temp files are free, clear all of our space
	if ( fs_loadStack == 0 ) {
		Hunk_ClearTempMemory();
	}
}

/*
============
FS_WriteFile

Filename are reletive to the quake search path
============
*/
void FS_WriteFile( const char *qpath, const void *buffer, int size ) {
	fileHandle_t f;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !qpath || !buffer ) {
		Com_Error( ERR_FATAL, "FS_WriteFile: NULL parameter" );
	}

	f = FS_FOpenFileWrite( qpath );
	if ( !f ) {
		Com_Printf( "Failed to open %s\n", qpath );
		return;
	}

	FS_Write( buffer, size, f );

	FS_FCloseFile( f );
}



/*
==========================================================================

ZIP FILE LOADING

==========================================================================
*/

/*
=================
FS_LoadZipFile

Creates a new pak_t in the search chain for the contents
of a zip file.
=================
*/
static pack_t *FS_LoadZipFile( char *zipfile, const char *basename )
{
	unzFile			uf;
	int				err;
	unz_global_info gi;
	char			filename_inzip[MAX_ZPATH];
	unz_file_info	file_info;
	int				i, len;
	long			hash;
	int				fs_numHeaderLongs;

	fs_numHeaderLongs = 0;

	uf = unzOpen(zipfile);
	err = unzGetGlobalInfo (uf,&gi);

	if (err != UNZ_OK)
		return NULL;

	fs_packFiles += gi.number_entry;

	len = 0;
	unzGoToFirstFile(uf);
	for (i = 0; i < gi.number_entry; i++)
	{
		err = unzGetCurrentFileInfo(uf, &file_info, filename_inzip, sizeof(filename_inzip), NULL, 0, NULL, 0);
		if (err != UNZ_OK) {
			break;
		}
		len += strlen(filename_inzip) + 1;
		unzGoToNextFile(uf);
	}

	fileInPack_t* buildBuffer = (fileInPack_t*)Z_Malloc( (gi.number_entry * sizeof( fileInPack_t )) + len );
	char* namePtr = ((char*)buildBuffer) + gi.number_entry * sizeof( fileInPack_t );
	int* fs_headerLongs = (int*)Z_Malloc( ( gi.number_entry + 1 ) * sizeof(int) );
	fs_headerLongs[ fs_numHeaderLongs++ ] = LittleLong( fs_checksumFeed );

	// get the hash table size from the number of files in the zip
	// because lots of custom pk3 files have less than 32 or 64 files
	for (i = 1; i <= MAX_FILEHASH_SIZE; i <<= 1) {
		if (i > gi.number_entry) {
			break;
		}
	}

	pack_t* pack = (pack_t*)Z_Malloc( sizeof( pack_t ) + i * sizeof(fileInPack_t *) );
	pack->hashSize = i;
	pack->hashTable = (fileInPack_t **) (((char *) pack) + sizeof( pack_t ));
	for(i = 0; i < pack->hashSize; i++) {
		pack->hashTable[i] = NULL;
	}

	Q_strncpyz( pack->pakFilename, zipfile, sizeof( pack->pakFilename ) );
	Q_strncpyz( pack->pakBasename, basename, sizeof( pack->pakBasename ) );

	// strip .pk3 if needed
	if ( strlen( pack->pakBasename ) > 4 && !Q_stricmp( pack->pakBasename + strlen( pack->pakBasename ) - 4, ".pk3" ) ) {
		pack->pakBasename[strlen( pack->pakBasename ) - 4] = 0;
	}

	pack->handle = uf;
	pack->numfiles = gi.number_entry;
	unzGoToFirstFile(uf);

	for (i = 0; i < gi.number_entry; i++)
	{
		err = unzGetCurrentFileInfo(uf, &file_info, filename_inzip, sizeof(filename_inzip), NULL, 0, NULL, 0);
		if (err != UNZ_OK) {
			break;
		}
		if (file_info.uncompressed_size > 0) {
			fs_headerLongs[fs_numHeaderLongs++] = LittleLong(file_info.crc);
		}
		Q_strlwr( filename_inzip );
		hash = Q_FileHash( filename_inzip, pack->hashSize );
		buildBuffer[i].name = namePtr;
		strcpy( buildBuffer[i].name, filename_inzip );
		namePtr += strlen(filename_inzip) + 1;
		// store the file position in the zip
		unzGetCurrentFileInfoPosition(uf, &buildBuffer[i].pos);
		//
		buildBuffer[i].next = pack->hashTable[hash];
		pack->hashTable[hash] = &buildBuffer[i];
		unzGoToNextFile(uf);
	}

	pack->checksum = Com_BlockChecksum( &fs_headerLongs[ 1 ], 4 * ( fs_numHeaderLongs - 1 ) );
	pack->pure_checksum = Com_BlockChecksum( fs_headerLongs, 4 * fs_numHeaderLongs );
	pack->checksum = LittleLong( pack->checksum );
	pack->pure_checksum = LittleLong( pack->pure_checksum );

	Z_Free(fs_headerLongs);

	pack->buildBuffer = buildBuffer;
	return pack;
}

/*
=================================================================================

DIRECTORY SCANNING FUNCTIONS

=================================================================================
*/

#define	MAX_FOUND_FILES	0x1000

static int FS_ReturnPath( const char *zname, char *zpath, int *depth ) {
	int len, at, newdep;

	newdep = 0;
	zpath[0] = 0;
	len = 0;
	at = 0;

	while(zname[at] != 0)
	{
		if (zname[at]=='/' || zname[at]=='\\') {
			len = at;
			newdep++;
		}
		at++;
	}
	strcpy(zpath, zname);
	zpath[len] = 0;
	*depth = newdep;

	return len;
}


static int FS_AddFileToList( const char *name, char *list[MAX_FOUND_FILES], int nfiles )
{
	int		i;

	if ( nfiles == MAX_FOUND_FILES - 1 ) {
		return nfiles;
	}
	for ( i = 0 ; i < nfiles ; i++ ) {
		if ( !Q_stricmp( name, list[i] ) ) {
			return nfiles;		// allready in list
		}
	}
	list[nfiles] = CopyString( name );
	nfiles++;

	return nfiles;
}


/*
Returns a uniqued list of files that match the given criteria
from all search paths
*/
static char** FS_ListFilteredFiles( const char *path, const char *extension, const char* filter, int *numfiles, int filters )
{
	int				nfiles;
	char			*list[MAX_FOUND_FILES];
	searchpath_t	*search;
	int				i;
	int				pathLength;
	int				extensionLength;
	int				length, pathDepth, temp;
	pack_t			*pak;
	fileInPack_t	*buildBuffer;
	char			zpath[MAX_ZPATH];

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !path ) {
		*numfiles = 0;
		return NULL;
	}
	if ( !extension ) {
		extension = "";
	}

	pathLength = strlen( path );
	if ( path[pathLength-1] == '\\' || path[pathLength-1] == '/' ) {
		pathLength--;
	}
	extensionLength = strlen( extension );
	nfiles = 0;
	FS_ReturnPath(path, zpath, &pathDepth);

	//
	// search through the path, one element at a time, adding to list
	//
	for (search = fs_searchpaths ; search ; search = search->next) {
		// is the element a pak file?
		if (search->pack && !(filters & FS_FILTER_INPAK)) {

			//ZOID:  If we are pure, don't search for files on paks that
			// aren't on the pure list
			if ( !FS_PakIsPure(search->pack) ) {
				continue;
			}

			// look through all the pak file elements
			pak = search->pack;
			buildBuffer = pak->buildBuffer;
			for (i = 0; i < pak->numfiles; i++) {
				char	*name;
				int		zpathLen, depth;

				// check for directory match
				name = buildBuffer[i].name;
				//
				if (filter) {
					// case insensitive
					if (!Com_FilterPath( filter, name ))
						continue;
					// unique the match
					nfiles = FS_AddFileToList( name, list, nfiles );
				}
				else {

					zpathLen = FS_ReturnPath(name, zpath, &depth);

					if ( (depth-pathDepth)>2 || pathLength > zpathLen || Q_stricmpn( name, path, pathLength ) ) {
						continue;
					}

					// check for extension match
					length = strlen( name );
					if ( length < extensionLength ) {
						continue;
					}

					if ( Q_stricmp( name + length - extensionLength, extension ) ) {
						continue;
					}
					// unique the match

					temp = pathLength;
					if (pathLength) {
						temp++;		// include the '/'
					}
					nfiles = FS_AddFileToList( name + temp, list, nfiles );
				}
			}
		} else if (search->dir && !(filters & FS_FILTER_NOTINPAK)) { // scan for files in the filesystem
			char	*netpath;
			int		numSysFiles;
			char	**sysFiles;
			char	*name;

			netpath = FS_BuildOSPath( search->dir->path, search->dir->gamedir, path );
			sysFiles = Sys_ListFiles( netpath, extension, filter, &numSysFiles, qfalse );
			for ( i = 0 ; i < numSysFiles ; i++ ) {
				// unique the match
				name = sysFiles[i];
				nfiles = FS_AddFileToList( name, list, nfiles );
			}
			Sys_FreeFileList( sysFiles );
		}
	}

	// return a copy of the list
	*numfiles = nfiles;

	if ( !nfiles ) {
		return NULL;
	}

	char** listCopy = (char**)Z_Malloc( ( nfiles + 1 ) * sizeof( *listCopy ) );
	for ( i = 0 ; i < nfiles ; i++ ) {
		listCopy[i] = list[i];
	}
	listCopy[i] = NULL;

	return listCopy;
}

/*
=================
FS_ListFiles
=================
*/
char **FS_ListFiles( const char *path, const char *extension, int *numfiles ) {
	return FS_ListFilteredFiles( path, extension, NULL, numfiles, 0 );
}

/*
=================
FS_FreeFileList
=================
*/
void FS_FreeFileList( char **list ) {
	int		i;

	if ( !fs_searchpaths ) {
		Com_Error( ERR_FATAL, "Filesystem call made without initialization\n" );
	}

	if ( !list ) {
		return;
	}

	for ( i = 0 ; list[i] ; i++ ) {
		Z_Free( list[i] );
	}

	Z_Free( list );
}


/*
================
FS_GetFileList
================
*/
int	FS_GetFileList(  const char *path, const char *extension, char *listbuf, int bufsize ) {
	int		nFiles, i, nTotal, nLen;
	char **pFiles = NULL;

	*listbuf = 0;
	nFiles = 0;
	nTotal = 0;

	if (Q_stricmp(path, "$modlist") == 0) {
		return FS_GetModList(listbuf, bufsize);
	}

	pFiles = FS_ListFiles(path, extension, &nFiles);

	for (i =0; i < nFiles; i++) {
		nLen = strlen(pFiles[i]) + 1;
		if (nTotal + nLen + 1 < bufsize) {
			strcpy(listbuf, pFiles[i]);
			listbuf += nLen;
			nTotal += nLen;
		}
		else {
			nFiles = i;
			break;
		}
	}

	FS_FreeFileList(pFiles);

	return nFiles;
}

/*
=======================
Sys_ConcatenateFileLists

mkv: Naive implementation. Concatenates three lists into a
     new list, and frees the old lists from the heap.
bk001129 - from cvs1.17 (mkv)

FIXME TTimo those two should move to common.c next to Sys_ListFiles
=======================
 */
static unsigned int Sys_CountFileList(char **list)
{
	int i = 0;

	if (list)
	{
		while (*list)
		{
			list++;
			i++;
		}
	}
	return i;
}

static char** Sys_ConcatenateFileLists( char **list0, char **list1 )
{
	int totalLength = 0;
	totalLength += Sys_CountFileList(list0);
	totalLength += Sys_CountFileList(list1);

	char** cat, **dst, **src;
	dst = cat = (char**)Z_Malloc( ( totalLength + 1 ) * sizeof( char* ) );

	/* Copy over lists. */
	if (list0)
	{
		for (src = list0; *src; src++, dst++)
			*dst = *src;
	}
	if (list1)
	{
		for (src = list1; *src; src++, dst++)
			*dst = *src;
	}

	// Terminate the list
	*dst = NULL;

	// Free our old lists.
	// NOTE: not freeing their content, it's been merged in dst and still being used
	if (list0) Z_Free( list0 );
	if (list1) Z_Free( list1 );

	return cat;
}

/*
================
FS_GetModList

Returns a list of mod directory names
A mod directory is a peer to baseq3 with a pk3 in it
The directories are searched in base path, cd path and home path
================
*/
int	FS_GetModList( char *listbuf, int bufsize ) {
	int		nMods, i, j, nTotal, nLen, nPaks, nPotential, nDescLen;
	char **pFiles = NULL;
	char **pPaks = NULL;
	char *name, *path;
	char descPath[MAX_OSPATH];
	fileHandle_t descHandle;

	int dummy;
	char **pFiles0 = NULL;
	char **pFiles1 = NULL;
	qbool bDrop = qfalse;

	*listbuf = 0;
	nMods = nPotential = nTotal = 0;

	pFiles0 = Sys_ListFiles( fs_homepath->string, NULL, NULL, &dummy, qtrue );
	pFiles1 = Sys_ListFiles( fs_basepath->string, NULL, NULL, &dummy, qtrue );
	// it is likely that we have duplicate names now, which we will cleanup below
	pFiles = Sys_ConcatenateFileLists( pFiles0, pFiles1 );
	nPotential = Sys_CountFileList(pFiles);

	for ( i = 0 ; i < nPotential ; i++ ) {
		name = pFiles[i];
		// NOTE: cleaner would involve more changes
		// ignore duplicate mod directories
		if (i!=0) {
			bDrop = qfalse;
			for(j=0; j<i; j++)
			{
				if (Q_stricmp(pFiles[j],name)==0) {
					// this one can be dropped
					bDrop = qtrue;
					break;
				}
			}
		}
		if (bDrop) {
			continue;
		}
		// we drop "baseq3" "." and ".."
		if (Q_stricmp(name, BASEGAME) && Q_stricmpn(name, ".", 1)) {
			// now we need to find some .pk3 files to validate the mod
			// NOTE TTimo: (actually I'm not sure why .. what if it's a mod under developement with no .pk3?)
			// we didn't keep the information when we merged the directory names, as to what OS Path it was found under
			//	 so it could be in base path, cd path or home path
			//	 we will try each three of them here (yes, it's a bit messy)
			path = FS_BuildOSPath( fs_basepath->string, name, "" );
			nPaks = 0;
			pPaks = Sys_ListFiles(path, ".pk3", NULL, &nPaks, qfalse); 
			Sys_FreeFileList( pPaks ); // we only use Sys_ListFiles to check wether .pk3 files are present

			/* try on home path */
			if ( nPaks <= 0 )
			{
				path = FS_BuildOSPath( fs_homepath->string, name, "" );
				nPaks = 0;
				pPaks = Sys_ListFiles( path, ".pk3", NULL, &nPaks, qfalse );
				Sys_FreeFileList( pPaks );
			}

			if (nPaks > 0) {
				nLen = strlen(name) + 1;
				// nLen is the length of the mod path
				// we need to see if there is a description available
				descPath[0] = '\0';
				Q_strncpyz(descPath, name, sizeof(descPath));
				Q_strcat(descPath, sizeof(descPath), "/description.txt");
				nDescLen = FS_SV_FOpenFileRead( descPath, &descHandle );
				if ( nDescLen > 0 && descHandle) {
					FILE *file;
					file = FS_FileForHandle(descHandle);
					Com_Memset( descPath, 0, sizeof( descPath ) );
					nDescLen = fread(descPath, 1, 48, file);
					if (nDescLen >= 0) {
						descPath[nDescLen] = '\0';
					}
					FS_FCloseFile(descHandle);
				} else {
					Q_strncpyz(descPath, name, sizeof(descPath));
				}
				nDescLen = strlen(descPath) + 1;

				if (nTotal + nLen + 1 + nDescLen + 1 < bufsize) {
					strcpy(listbuf, name);
					listbuf += nLen;
					strcpy(listbuf, descPath);
					listbuf += nDescLen;
					nTotal += nLen + nDescLen;
					nMods++;
				}
				else {
					break;
				}
			}
		}
	}
	Sys_FreeFileList( pFiles );

	return nMods;
}


////////////////////////////////////////////////////////////////


static void FS_Dir_f()
{
	char	**dirnames;
	int		ndirs;
	int		i;

	if ( Cmd_Argc() < 2 || Cmd_Argc() > 3 ) {
		Com_Printf( "usage: dir <directory> [extension]\n" );
		return;
	}

	const char* path = Cmd_Argv( 1 );
	const char* extension = (Cmd_Argc() == 2) ? "" : Cmd_Argv( 2 );

	Com_Printf( "Directory of %s %s\n", path, extension );
	Com_Printf( "---------------\n" );

	dirnames = FS_ListFiles( path, extension, &ndirs );

	for ( i = 0; i < ndirs; i++ ) {
		Com_Printf( "%s\n", dirnames[i] );
	}

	FS_FreeFileList( dirnames );
}


static void FS_ConvertPath( char *s )
{
	while (*s) {
		if ( *s == '\\' || *s == ':' ) {
			*s = '/';
		}
		s++;
	}
}


// ignore case and seprator char distinctions

int FS_PathCmp( const char *s1, const char *s2 )
{
	int		c1, c2;

	do {
		c1 = *s1++;
		c2 = *s2++;

		if (c1 >= 'a' && c1 <= 'z') {
			c1 -= ('a' - 'A');
		}
		if (c2 >= 'a' && c2 <= 'z') {
			c2 -= ('a' - 'A');
		}

		if ( c1 == '\\' || c1 == ':' ) {
			c1 = '/';
		}
		if ( c2 == '\\' || c2 == ':' ) {
			c2 = '/';
		}

		if (c1 < c2) {
			return -1;
		}
		if (c1 > c2) {
			return 1;
		}
	} while (c1);

	return 0;		// strings are equal
}


static void FS_SortFileList(char **filelist, int numfiles)
{
	int i, j, k;

	char** sortedlist = (char**)Z_Malloc( ( numfiles + 1 ) * sizeof( *sortedlist ) );
	sortedlist[0] = NULL;
	int numsortedfiles = 0;

	for (i = 0; i < numfiles; i++) {
		for (j = 0; j < numsortedfiles; j++) {
			if (FS_PathCmp(filelist[i], sortedlist[j]) < 0) {
				break;
			}
		}
		for (k = numsortedfiles; k > j; k--) {
			sortedlist[k] = sortedlist[k-1];
		}
		sortedlist[j] = filelist[i];
		numsortedfiles++;
	}

	Com_Memcpy(filelist, sortedlist, numfiles * sizeof( *filelist ) );
	Z_Free(sortedlist);
}


static void FS_NewDir_f()
{
	char	**dirnames;
	int		ndirs;
	int		i;

	if ( Cmd_Argc() < 2 ) {
		Com_Printf( "usage: fdir <filter>\n" );
		Com_Printf( "example: fdir *q3dm*.bsp\n");
		return;
	}

	Com_Printf( "---------------\n" );

	dirnames = FS_ListFilteredFiles( "", "", Cmd_Argv(1), &ndirs, 0 );

	FS_SortFileList(dirnames, ndirs);

	for ( i = 0; i < ndirs; i++ ) {
		FS_ConvertPath(dirnames[i]);
		Com_Printf( "%s\n", dirnames[i] );
	}

	Com_Printf( "%d files listed\n", ndirs );
	FS_FreeFileList( dirnames );
}


static void FS_Path_f()
{
	int i;
	const searchpath_t* s;

	Com_Printf ("Current search path:\n");
	for (s = fs_searchpaths; s; s = s->next) {
		if (s->pack) {
			if (!fs_numServerPaks || FS_PakIsPure(s->pack)) {
				Com_Printf( "OK: %s (%i files)\n", s->pack->pakFilename, s->pack->numfiles);
			} else {
				Com_DPrintf( "IMPURE: %s (%i files)\n", s->pack->pakFilename, s->pack->numfiles);
			}
		} else {
			Com_Printf( "%s/%s\n", s->dir->path, s->dir->gamedir );
		}
	}

	Com_Printf( "\n" );
	for ( i = 1 ; i < MAX_FILE_HANDLES ; i++ ) {
		if ( fsh[i].handleFiles.file.o ) {
			Com_Printf( "handle %i: %s\n", i, fsh[i].name );
		}
	}
}


//===========================================================================


static int QDECL paksort( const void *a, const void *b ) {
	char	*aa, *bb;

	aa = *(char **)a;
	bb = *(char **)b;

	return FS_PathCmp( aa, bb );
}

/*
================
FS_AddGameDirectory

Sets fs_gamedir, adds the directory to the head of the path,
then loads the zip headers
================
*/
static void FS_AddGameDirectory( const char *path, const char *dir )
{
	searchpath_t	*sp;
	int				i;
	pack_t			*pak;
	char			*pakfile;
	int				numfiles;
	char			**pakfiles;

	// this fixes the case where fs_basepath is the same as fs_cdpath, which happens on full installs
	// KHB  preserved despite removal of fs_cdpath, just in case base/home has the same problem on *nix
	for ( sp = fs_searchpaths ; sp ; sp = sp->next ) {
		if ( sp->dir && !Q_stricmp(sp->dir->path, path) && !Q_stricmp(sp->dir->gamedir, dir)) {
			return;			// we've already got this one
		}
	}

	Q_strncpyz( fs_gamedir, dir, sizeof( fs_gamedir ) );

	// add the directory to the search path
	searchpath_t* search = Z_New<searchpath_t>();
	search->dir = Z_New<directory_t>();

	Q_strncpyz( search->dir->path, path, sizeof( search->dir->path ) );
	Q_strncpyz( search->dir->gamedir, dir, sizeof( search->dir->gamedir ) );
	search->next = fs_searchpaths;
	fs_searchpaths = search;

	// find all pak files in this directory
	pakfile = FS_BuildOSPath( path, dir, "" );
	pakfile[ strlen(pakfile) - 1 ] = 0;	// strip the trailing slash

	pakfiles = Sys_ListFiles( pakfile, ".pk3", NULL, &numfiles, qfalse );

	// sort them so that later alphabetic matches override
	// earlier ones.  This makes pak1.pk3 override pak0.pk3
	if ( numfiles > MAX_PAKFILES ) {
		numfiles = MAX_PAKFILES;
	}

	char *sorted[MAX_PAKFILES];
	for ( i = 0 ; i < numfiles ; i++ ) {
		sorted[i] = pakfiles[i];
	}

	qsort( sorted, numfiles, sizeof(char*), paksort );

	for ( i = 0 ; i < numfiles ; i++ ) {
		pakfile = FS_BuildOSPath( path, dir, sorted[i] );
		if ( ( pak = FS_LoadZipFile( pakfile, sorted[i] ) ) == 0 )
			continue;
		// store the game name for downloading
		strcpy(pak->pakGamename, dir);

		search = Z_New<searchpath_t>();
		search->pack = pak;
		search->next = fs_searchpaths;
		fs_searchpaths = search;
	}

	// done
	Sys_FreeFileList( pakfiles );
}


qbool FS_idPak( const char* pak, const char* base )
{
	for (int i = 0; i < NUM_ID_PAKS; ++i) {
		if ( !FS_FilenameCompare(pak, va("%s/pak%d", base, i)) ) {
			return qtrue;
		}
	}

	return qfalse;
}



// check whether the string contains stuff like "../"
// to prevent directory traversal bugs

qbool FS_CheckDirTraversal(const char *checkdir)
{
	return (strstr(checkdir, "../") || strstr(checkdir, "..\\"));
}


/*
dlstring == qtrue

Returns a list of pak files that we should download from the server. They all get stored
in the current gamedir and an FS_Restart will be fired up after we download them all.

The string is the format:

@remotename@localname [repeat]

static int		fs_numServerReferencedPaks;
static int		fs_serverReferencedPaks[MAX_SEARCH_PATHS];
static char		*fs_serverReferencedPakNames[MAX_SEARCH_PATHS];

----------------
dlstring == qfalse

we are not interested in a download string format, we want something human-readable
(this is used for diagnostics while connecting to a pure server)

================
*/
qbool FS_ComparePaks( char *neededpaks, int len, qbool dlstring ) {
	searchpath_t	*sp;
	qbool havepak, badchecksum;
	char *origpos = neededpaks;
	int i;

	if (!fs_numServerReferencedPaks)
		return qfalse; // Server didn't send any pack information along

	*neededpaks = 0;

	for ( i = 0 ; i < fs_numServerReferencedPaks ; i++ )
	{
		// Ok, see if we have this pak file
		badchecksum = qfalse;
		havepak = qfalse;

		// never autodownload any of the id paks
		if ( FS_idPak(fs_serverReferencedPakNames[i], BASEGAME) || FS_idPak(fs_serverReferencedPakNames[i], "missionpack") ) {
			continue;
		}

		// Make sure the server cannot make us write to non-quake3 directories.
		if(FS_CheckDirTraversal(fs_serverReferencedPakNames[i]))
                {
			Com_Printf("WARNING: Invalid download name %s\n", fs_serverReferencedPakNames[i]);
                        continue;
                }

		for ( sp = fs_searchpaths ; sp ; sp = sp->next ) {
			if ( sp->pack && sp->pack->checksum == fs_serverReferencedPaks[i] ) {
				havepak = qtrue; // This is it!
				break;
			}
		}

		if ( !havepak && fs_serverReferencedPakNames[i] && *fs_serverReferencedPakNames[i] ) { 
			// Don't got it

      if (dlstring)
      {
	// We need this to make sure we won't hit the end of the buffer or the server could
	// overwrite non-pk3 files on clients by writing so much crap into neededpaks that
	// Q_strcat cuts off the .pk3 extension.
	
	origpos += strlen(origpos);
	
        // Remote name
        Q_strcat( neededpaks, len, "@");
        Q_strcat( neededpaks, len, fs_serverReferencedPakNames[i] );
        Q_strcat( neededpaks, len, ".pk3" );

        // Local name
        Q_strcat( neededpaks, len, "@");
        // Do we have one with the same name?
        if ( FS_SV_FileExists( va( "%s.pk3", fs_serverReferencedPakNames[i] ) ) )
        {
          char st[MAX_ZPATH];
          // We already have one called this, we need to download it to another name
          // Make something up with the checksum in it
          Com_sprintf( st, sizeof( st ), "%s.%08x.pk3", fs_serverReferencedPakNames[i], fs_serverReferencedPaks[i] );
          Q_strcat( neededpaks, len, st );
        } else
        {
          Q_strcat( neededpaks, len, fs_serverReferencedPakNames[i] );
          Q_strcat( neededpaks, len, ".pk3" );
        }
        
        // Find out whether it might have overflowed the buffer and don't add this file to the
        // list if that is the case.
        if(strlen(origpos) + (origpos - neededpaks) >= len - 1)
	{
		*origpos = '\0';
		break;
	}
      }
      else
      {
        Q_strcat( neededpaks, len, fs_serverReferencedPakNames[i] );
			  Q_strcat( neededpaks, len, ".pk3" );
        // Do we have one with the same name?
        if ( FS_SV_FileExists( va( "%s.pk3", fs_serverReferencedPakNames[i] ) ) )
        {
          Q_strcat( neededpaks, len, " (local file exists with wrong checksum)");
        }
        Q_strcat( neededpaks, len, "\n");
      }
		}
	}

	if ( *neededpaks ) {
		return qtrue;
	}

	return qfalse; // We have them all
}


void FS_MissingPaks( unsigned int* checksums, int* checksumCount, int maxChecksums )
{
	int count = 0;
	for (int i = 0; i < fs_numServerReferencedPaks; i++) {
		// ignore official paks
		if (FS_idPak(fs_serverReferencedPakNames[i], BASEGAME))
			continue;

		qbool gotIt = qfalse;
		for (searchpath_t* sp = fs_searchpaths; sp; sp = sp->next) {
			if (sp->pack && sp->pack->checksum == fs_serverReferencedPaks[i]) {
				gotIt = qtrue;
				break;
			}
		}

		if (gotIt)
			continue;

		checksums[count++] = fs_serverReferencedPaks[i];

		if (count == maxChecksums) {
			Com_Printf("^3WARNING: FS_MissingPaks has too many checksums for the array given (over %d)\n", maxChecksums);
			break;
		}
	}

	*checksumCount = count;
}


qbool FS_PakExists( unsigned int checksum )
{
	for (searchpath_t* sp = fs_searchpaths; sp; sp = sp->next) {
		if (sp->pack && sp->pack->checksum == checksum)
			return qtrue;
	}

	return qfalse;
}


static void FS_Restart_f()
{
	FS_Restart(fs_checksumFeed);
}


static const cmdTableItem_t fs_cmds[] =
{
	{ "path", FS_Path_f, NULL, "prints info about the current search path" },
	{ "dir", FS_Dir_f, NULL, "prints an extension-filtered file list" },
	{ "fdir", FS_NewDir_f, NULL, "prints a pattern-filtered file list" },
	{ "fs_restart", FS_Restart_f, NULL, "restarts the file system" }
};


/*
================
FS_Shutdown

Frees all resources and closes all files
================
*/
void FS_Shutdown( qbool closemfp ) {
	searchpath_t	*p, *next;
	int	i;

	for(i = 0; i < MAX_FILE_HANDLES; i++) {
		if (fsh[i].fileSize) {
			FS_FCloseFile(i);
		}
	}

	// free everything
	for ( p = fs_searchpaths ; p ; p = next ) {
		next = p->next;

		if ( p->pack ) {
			unzClose(p->pack->handle);
			Z_Free( p->pack->buildBuffer );
			Z_Free( p->pack );
		}
		if ( p->dir ) {
			Z_Free( p->dir );
		}
		Z_Free( p );
	}

	// any FS_ calls will now be an error until reinitialized
	fs_searchpaths = NULL;

	Cmd_UnregisterArray( fs_cmds );

#ifdef FS_MISSING
	if (closemfp) {
		fclose(missingFiles);
	}
#endif
}

void Com_AppendCDKey( const char *filename );
void Com_ReadCDKey( const char *filename );

/*
NOTE TTimo: the reordering that happens here is not reflected in the cvars (\cvarlist *pak*)
  this can lead to misleading situations, see https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=540
*/
static void FS_ReorderPurePaks()
{
	searchpath_t *s;
	int i;
	searchpath_t **p_insert_index, // for linked list reordering
		**p_previous; // when doing the scan

	// only relevant when connected to pure server
	if ( !fs_numServerPaks )
		return;

	fs_reordered = qfalse;

	p_insert_index = &fs_searchpaths; // we insert in order at the beginning of the list 
	for ( i = 0 ; i < fs_numServerPaks ; i++ ) {
		p_previous = p_insert_index; // track the pointer-to-current-item
		for (s = *p_insert_index; s; s = s->next) {
			// the part of the list before p_insert_index has been sorted already
			if (s->pack && fs_serverPaks[i] == s->pack->checksum) {
				fs_reordered = qtrue;
				// move this element to the insert list
				*p_previous = s->next;
				s->next = *p_insert_index;
				*p_insert_index = s;
				// increment insert list
				p_insert_index = &s->next;
				break; // iterate to next server pack
			}
			p_previous = &s->next; 
		}
	}
}


static void FS_Startup( const char *gameName )
{
	QSUBSYSTEM_INIT_START( "FileSystem" );

	//each map load increment 'fs_packFiles'!
	//start cnq3: 30298 files in pk3 files
	//next map: 60596 files in pk3 files
	//next map: 90894 files in pk3 files
	//etc
	fs_packFiles = 0; 

	fs_debug = Cvar_Get( "fs_debug", "0", 0 );
	Cvar_SetRange( "fs_debug", CVART_BOOL, NULL, NULL );
	Cvar_SetHelp( "fs_debug", "prints file open/write accesses" );
	fs_basepath = Cvar_Get ("fs_basepath", Sys_Cwd(), CVAR_INIT );
	fs_basegame = Cvar_Get ("fs_basegame", "", CVAR_INIT );
	fs_gamedirvar = Cvar_Get ("fs_game", APEXGAME, CVAR_INIT | CVAR_SYSTEMINFO );
	Cvar_SetHelp( "fs_game", "name of the mod folder" );
	const char* homePath = Sys_DefaultHomePath();
	if (!homePath || !homePath[0])
		homePath = fs_basepath->string;
	fs_homepath = Cvar_Get ("fs_homepath", homePath, CVAR_INIT );

	// add search path elements in reverse priority order
	if (fs_basepath->string[0]) {
		FS_AddGameDirectory( fs_basepath->string, gameName );
	}
	// fs_homepath is somewhat particular to *nix systems, only add if relevant
	// NOTE: same filtering below for mods and basegame
	if (fs_basepath->string[0] && Q_stricmp(fs_homepath->string,fs_basepath->string)) {
		FS_AddGameDirectory ( fs_homepath->string, gameName );
	}

	// check for additional base game so mods can be based upon other mods
	if ( fs_basegame->string[0] && !Q_stricmp( gameName, BASEGAME ) && Q_stricmp( fs_basegame->string, gameName ) ) {
		if (fs_basepath->string[0]) {
			FS_AddGameDirectory(fs_basepath->string, fs_basegame->string);
		}
		if (fs_homepath->string[0] && Q_stricmp(fs_homepath->string,fs_basepath->string)) {
			FS_AddGameDirectory(fs_homepath->string, fs_basegame->string);
		}
	}

	// check for additional game folder for mods
	if ( fs_gamedirvar->string[0] && !Q_stricmp( gameName, BASEGAME ) && Q_stricmp( fs_gamedirvar->string, gameName ) ) {
		if (fs_basepath->string[0]) {
			FS_AddGameDirectory(fs_basepath->string, fs_gamedirvar->string);
		}
		if (fs_homepath->string[0] && Q_stricmp(fs_homepath->string,fs_basepath->string)) {
			FS_AddGameDirectory(fs_homepath->string, fs_gamedirvar->string);
		}
	}

	Com_ReadCDKey(BASEGAME);
	if (fs_gamedirvar && fs_gamedirvar->string[0] != 0) {
		Com_AppendCDKey( fs_gamedirvar->string );
	}

	// add our commands
	Cmd_RegisterArray( fs_cmds, MODULE_COMMON );

	// https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=506
	// reorder the pure pk3 files according to server order
	FS_ReorderPurePaks();

	fs_gamedirvar->modified = qfalse; // We just loaded, it's not modified

#ifdef FS_MISSING
	if (missingFiles == NULL) {
		missingFiles = fopen( "\\missing.txt", "ab" );
	}
#endif

	Com_Printf( "%d files in pk3 files\n", fs_packFiles );
	QSUBSYSTEM_INIT_DONE( "FileSystem" );
}


#define DEFAULT_PAK_COUNT 9

static const int DefaultPakChecksums[DEFAULT_PAK_COUNT] = {
	1566731103,
	298122907,
	412165236,
	-1303471980,
	1197932710,
	-207895723,
	-585902437,
	908855077,
	977125798
};


/*
===================
FS_CheckPaks

Checks that pak0.pk3 to pakN.pk3 are present and
their checksums correct, N being DEFAULT_PAK_COUNT
Note: If you're building a game that doesn't depend on the
Q3 media pak0-N.pk3, you'll want to remove this function
===================
*/
static void FS_CheckPaks()
{
	enum defaultPakStatus_t {
		DPS_FOUND = 1,
		DPS_VALID = 2
	};

	int status[DEFAULT_PAK_COUNT] = { 0 };
	int badChecksums[DEFAULT_PAK_COUNT] = { 0 };
	int found = 0;

	for( searchpath_t* path = fs_searchpaths; path; path = path->next ) {
		for ( int i = 0; i < DEFAULT_PAK_COUNT; ++i ) {
			if ( status[i] & DPS_FOUND )
				continue;

			if ( path->pack &&
				!Q_stricmpn(path->pack->pakBasename, va("pak%d", i), MAX_OSPATH) &&
				!Q_stricmpn(path->pack->pakGamename, BASEGAME, MAX_OSPATH) ) {
				++found;
				status[i] |= DPS_FOUND;
				if ( path->pack->checksum == DefaultPakChecksums[i] )
					status[i] |= DPS_VALID;
				else
					badChecksums[i] = path->pack->checksum;
			}
		}

		if ( found == DEFAULT_PAK_COUNT )
			break;
	}

	if ( found < DEFAULT_PAK_COUNT ) {
		int firstMissing = 0;
		for ( int i = 0; i < DEFAULT_PAK_COUNT; ++i ) {
			if ( !(status[i] & DPS_FOUND) ) {
				firstMissing = i;
				break;
			}
		}
		Com_Error( ERR_FATAL, "pak%d.pk3 is missing or unreadable! Check that CNQ3 is in the correct place "
				  "and that every file in the %s directory is present and readable.", firstMissing, BASEGAME );
		return;
	}

	for ( int i = 0; i < DEFAULT_PAK_COUNT; ++i ) {
		if ( !(status[i] & DPS_VALID) ) {
			Com_Error( ERR_FATAL, "pak%d.pk3 is corrupt! Please re-copy pak%d.pk3 "
					  "from your legitimate Q3 CD-ROM. Got checksum %X, expected %X.",
					  i, i, (unsigned int)badChecksums[i], (unsigned int)DefaultPakChecksums[i] );
			return;
		}
	}
}


/*
=====================
FS_LoadedPakChecksums

Returns a space separated string containing the checksums of all loaded pk3 files.
Servers with sv_pure set will get this string and pass it to clients.
=====================
*/
const char *FS_LoadedPakChecksums( void ) {
	static char	info[BIG_INFO_STRING];
	searchpath_t	*search;

	info[0] = 0;

	for ( search = fs_searchpaths ; search ; search = search->next ) {
		// is the element a pak file? 
		if ( !search->pack ) {
			continue;
		}

		Q_strcat( info, sizeof( info ), va("%i ", search->pack->checksum ) );
	}

	return info;
}

/*
=====================
FS_LoadedPakPureChecksums

Returns a space separated string containing the pure checksums of all loaded pk3 files.
Servers with sv_pure use these checksums to compare with the checksums the clients send
back to the server.
=====================
*/
const char *FS_LoadedPakPureChecksums( void ) {
	static char	info[BIG_INFO_STRING];
	searchpath_t	*search;

	info[0] = 0;

	for ( search = fs_searchpaths ; search ; search = search->next ) {
		// is the element a pak file? 
		if ( !search->pack ) {
			continue;
		}

		Q_strcat( info, sizeof( info ), va("%i ", search->pack->pure_checksum ) );
	}

	return info;
}

/*
=====================
FS_ReferencedPakChecksums

Returns a space separated string containing the checksums of all referenced pk3 files.
The server will send this to the clients so they can check which files should be auto-downloaded. 
=====================
*/
const char *FS_ReferencedPakChecksums( void ) {
	static char	info[BIG_INFO_STRING];
	searchpath_t *search;

	info[0] = 0;

	for ( search = fs_searchpaths ; search ; search = search->next ) {
		// is the element a pak file?
		if ( search->pack ) {
			if (search->pack->referenced || Q_stricmpn(search->pack->pakGamename, BASEGAME, strlen(BASEGAME))) {
				Q_strcat( info, sizeof( info ), va("%i ", search->pack->checksum ) );
			}
		}
	}

	return info;
}


/*
returns a space-separated string containing the pure checksums of all referenced pk3 files
servers with sv_pure set will get this string back from clients for pure validation
the string has a specific order, "cgame ui @ ref1 ref2 ref3 ..."
*/
const char* FS_ReferencedPakPureChecksums()
{
	static char info[BIG_INFO_STRING];
	info[0] = 0;

	int numPaks = 0;
	int checksum = fs_checksumFeed;

	for (int nFlags = FS_CGAME_REF; nFlags; nFlags = nFlags >> 1) {
		if (nFlags & FS_GENERAL_REF) {
			// add a delimter between must haves and general refs
			Q_strcat(info, sizeof(info), "@ ");
		}
		for ( const searchpath_t* search = fs_searchpaths; search; search = search->next ) {
			// is the element a pak file and has it been referenced based on flag?
			if ( search->pack && (search->pack->referenced & nFlags)) {
				Q_strcat( info, sizeof( info ), va("%i ", search->pack->pure_checksum) );
				if (nFlags & (FS_CGAME_REF | FS_UI_REF)) {
					break;
				}
				checksum ^= search->pack->pure_checksum;
				numPaks++;
			}
		}
	}

	// last checksum is the encoded number of referenced pk3s
	checksum ^= numPaks;
	Q_strcat( info, sizeof( info ), va("%i ", checksum ) );

	return info;
}


/*
returns a space separated string containing the names of all referenced pk3 files
the server will send this to the clients so they can check which files should be auto-downloaded
*/
const char* FS_ReferencedPakNames()
{
	static char info[BIG_INFO_STRING];
	info[0] = 0;

	// we want to return ALL pk3's from the fs_game path
	// and referenced ones from baseq3
	for ( const searchpath_t* search = fs_searchpaths; search; search = search->next ) {
		// is the element a pak file?
		if ( search->pack ) {
			if (search->pack->referenced || Q_stricmpn(search->pack->pakGamename, BASEGAME, strlen(BASEGAME))) {
				if (*info)
					Q_strcat(info, sizeof( info ), " " );
				Q_strcat( info, sizeof( info ), search->pack->pakGamename );
				Q_strcat( info, sizeof( info ), "/" );
				Q_strcat( info, sizeof( info ), search->pack->pakBasename );
			}
		}
	}

	return info;
}


/*
=====================
FS_ClearPakReferences
=====================
*/
void FS_ClearPakReferences( int flags ) {
	searchpath_t *search;

	if ( !flags ) {
		flags = -1;
	}
	for ( search = fs_searchpaths; search; search = search->next ) {
		// is the element a pak file and has it been referenced?
		if ( search->pack ) {
			search->pack->referenced &= ~flags;
		}
	}
}


/*
=====================
FS_PureServerSetLoadedPaks

If the string is empty, all data sources will be allowed.
If not empty, only pk3 files that match one of the space
separated checksums will be checked for files, with the
exception of .cfg and .dat files.
=====================
*/
void FS_PureServerSetLoadedPaks( const char *pakSums ) {
	Cmd_TokenizeString( pakSums );

	int c = Cmd_Argc();
	if ( c > MAX_SEARCH_PATHS ) {
		c = MAX_SEARCH_PATHS;
	}

	fs_numServerPaks = c;

	for ( int i = 0 ; i < c ; i++ ) {
		fs_serverPaks[i] = atoi( Cmd_Argv( i ) );
	}

	if (fs_numServerPaks) {
		Com_DPrintf( "Connected to a pure server.\n" );
	}
	else
	{
		if (fs_reordered)
		{
			// https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=540
			// force a restart to make sure the search order will be correct
			Com_DPrintf( "FS search reorder is required\n" );
			FS_Restart(fs_checksumFeed);
			return;
		}
	}
}

/*
=====================
FS_PureServerSetReferencedPaks

The checksums and names of the pk3 files referenced at the server
are sent to the client and stored here. The client will use these
checksums to see if any pk3 files need to be auto-downloaded. 
=====================
*/
void FS_PureServerSetReferencedPaks( const char *pakSums, const char *pakNames ) {
	int		i, c, d = 0;

	Cmd_TokenizeString( pakSums );

	c = Cmd_Argc();
	if ( c > MAX_SEARCH_PATHS ) {
		c = MAX_SEARCH_PATHS;
	}

	for ( i = 0 ; i < c ; i++ ) {
		fs_serverReferencedPaks[i] = atoi( Cmd_Argv( i ) );
	}

	for (i = 0 ; i < sizeof(fs_serverReferencedPakNames) / sizeof(*fs_serverReferencedPakNames); i++)
	{
		if(fs_serverReferencedPakNames[i])
			Z_Free(fs_serverReferencedPakNames[i]);

		fs_serverReferencedPakNames[i] = NULL;
	}

	if ( pakNames && *pakNames ) {
		Cmd_TokenizeString( pakNames );

		d = Cmd_Argc();

		if(d > c)
			d = c;

		for ( i = 0 ; i < d ; i++ ) {
			fs_serverReferencedPakNames[i] = CopyString( Cmd_Argv( i ) );
		}
	}

	// ensure that there are as many checksums as there are pak names.
	if(d < c)
		c = d;

	fs_numServerReferencedPaks = c;
}


// called only at initial startup, not when the filesystem is resetting due to a game change

void FS_InitFilesystem()
{
	Com_Printf( "Working directory: %s\n", Sys_Cwd() );

	// allow command line parms to override our defaults
	// we have to handle this specially, because normal command
	// line variable sets don't happen until after the filesystem
	// has already been initialized
	Com_StartupVariable( "fs_basepath" );
	Com_StartupVariable( "fs_homepath" );
	Com_StartupVariable( "fs_game" );

	// try to start up normally
	FS_Startup( BASEGAME );

	FS_CheckPaks();

	// if we can't find default.cfg, assume that the paths are busted
	// and error out now, rather than getting an unreadable
	// graphics screen when the font fails to load
	if ( FS_ReadFile( "default.cfg", NULL ) <= 0 )
		Com_Error( ERR_FATAL, "Couldn't load default.cfg" );

	Q_strncpyz( lastValidBase, fs_basepath->string, sizeof(lastValidBase) );
	Q_strncpyz( lastValidGame, fs_gamedirvar->string, sizeof(lastValidGame) );
}


/*
================
FS_Restart
================
*/
void FS_Restart( int checksumFeed ) {

	// free anything we currently have loaded
	FS_Shutdown(qfalse);

	// set the checksum feed
	fs_checksumFeed = checksumFeed;

	// clear pak references
	FS_ClearPakReferences(0);

	// try to start up normally
	FS_Startup( BASEGAME );

	FS_CheckPaks();

	// if we can't find default.cfg, assume that the paths are
	// busted and error out now, rather than getting an unreadable
	// graphics screen when the font fails to load
	if ( FS_ReadFile( "default.cfg", NULL ) <= 0 ) {
		// this might happen when connecting to a pure server not using BASEGAME/pak0.pk3
		// (for instance a TA demo server)
		if (lastValidBase[0]) {
			FS_PureServerSetLoadedPaks("");
			Cvar_Set("fs_basepath", lastValidBase);
			Cvar_Set("fs_gamedirvar", lastValidGame);
			lastValidBase[0] = '\0';
			lastValidGame[0] = '\0';
			FS_Restart(checksumFeed);
			Com_Error( ERR_DROP, "Invalid game folder\n" );
			return;
		}
		Com_Error( ERR_FATAL, "Couldn't load default.cfg" );
	}

	// bk010116 - new check before safeMode
	if ( Q_stricmp(fs_gamedirvar->string, lastValidGame) ) {
		// skip the q3config.cfg if "safe" is on the command line
		if ( !Com_SafeMode() ) {
			Cbuf_AddText ("exec q3config.cfg\n");
		}
	}

	Q_strncpyz(lastValidBase, fs_basepath->string, sizeof(lastValidBase));
	Q_strncpyz(lastValidGame, fs_gamedirvar->string, sizeof(lastValidGame));

}


/*
=================
FS_ConditionalRestart
restart if necessary
=================
*/
void FS_ConditionalRestart( int checksumFeed ) {
	if( fs_gamedirvar->modified || checksumFeed != fs_checksumFeed ) {
		FS_Restart( checksumFeed );
	} else if ( fs_numServerPaks && !fs_reordered ) {
		FS_ReorderPurePaks();
	}
}

/*
========================================================================================

Handle based file calls for virtual machines

========================================================================================
*/

int FS_FOpenFileByMode( const char *qpath, fileHandle_t *f, fsMode_t mode ) {
	int		r;
	qbool	sync;

	sync = qfalse;

	switch( mode ) {
	case FS_READ:
		r = FS_FOpenFileRead( qpath, f, qtrue );
		break;
	case FS_WRITE:
		*f = FS_FOpenFileWrite( qpath );
		r = 0;
		if (*f == 0) {
			r = -1;
		}
		break;
	case FS_APPEND_SYNC:
		sync = qtrue;
	case FS_APPEND:
		*f = FS_FOpenFileAppend( qpath );
		r = 0;
		if (*f == 0) {
			r = -1;
		}
		break;
	default:
		Com_Error( ERR_FATAL, "FS_FOpenFileByMode: bad mode" );
		return -1;
	}

	if (!f) {
		return r;
	}

	if ( *f ) {
		if (fsh[*f].zipFile == qtrue) {
			fsh[*f].baseOffset = unztell(fsh[*f].handleFiles.file.z);
		} else {
			fsh[*f].baseOffset = ftell(fsh[*f].handleFiles.file.o);
		}
		fsh[*f].fileSize = r;
	}
	fsh[*f].handleSync = sync;

	return r;
}

int FS_FTell( fileHandle_t f ) {
	int pos;
	if (fsh[f].zipFile == qtrue) {
		pos = unztell(fsh[f].handleFiles.file.z);
	} else {
		pos = ftell(fsh[f].handleFiles.file.o);
	}
	return pos;
}

void FS_Flush( fileHandle_t f ) {
	fflush(fsh[f].handleFiles.file.o);
}

void FS_FilenameCompletion( const char *dir, const char *ext, qbool stripExt, 
							void(*callback)(const char *s), int filters ) {
	char	**filenames;
	int		nfiles;
	int		i;
	char	filename[ MAX_STRING_CHARS ];

	filenames = FS_ListFilteredFiles( dir, ext, NULL, &nfiles, filters );

	FS_SortFileList( filenames, nfiles );

	for( i = 0; i < nfiles; i++ ) {
		FS_ConvertPath( filenames[ i ] );
		Q_strncpyz( filename, filenames[ i ], MAX_STRING_CHARS );

		if( stripExt ) {
			COM_StripExtension(filename, filename, sizeof(filename));
		}

		callback( filename );
	}
	FS_FreeFileList( filenames );
}