path: root/source3/smbd/mangle_hash.c

/* 
   Unix SMB/CIFS implementation.
   Name mangling
   Copyright (C) Andrew Tridgell 1992-2002
   Copyright (C) Simo Sorce 2001
   Copyright (C) Andrew Bartlett 2002
   
   This program 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.
   
   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/


/* -------------------------------------------------------------------------- **
 * Notable problems...
 *
 *  March/April 1998  CRH
 *  - Many of the functions in this module overwrite string buffers passed to
 *    them.  This causes a variety of problems and is, generally speaking,
 *    dangerous and scarry.  See the kludge notes in name_map()
 *    below.
 *  - It seems that something is calling name_map() twice.  The
 *    first call is probably some sort of test.  Names which contain
 *    illegal characters are being doubly mangled.  I'm not sure, but
 *    I'm guessing the problem is in server.c.
 *
 * -------------------------------------------------------------------------- **
 */

/* -------------------------------------------------------------------------- **
 * History...
 *
 *  March/April 1998  CRH
 *  Updated a bit.  Rewrote is_mangled() to be a bit more selective.
 *  Rewrote the mangled name cache.  Added comments here and there.
 *  &c.
 * -------------------------------------------------------------------------- **
 */

#include "includes.h"


/* -------------------------------------------------------------------------- **
 * External Variables...
 */

extern int case_default;    /* Are conforming 8.3 names all upper or lower?   */
extern BOOL case_mangle;    /* If true, all chars in 8.3 should be same case. */

/* -------------------------------------------------------------------------- **
 * Other stuff...
 *
 * magic_char     - This is the magic char used for mangling.  It's
 *                  global.  There is a call to lp_magicchar() in server.c
 *                  that is used to override the initial value.
 *
 * MANGLE_BASE    - This is the number of characters we use for name mangling.
 *
 * basechars      - The set characters used for name mangling.  This
 *                  is static (scope is this file only).
 *
 * mangle()       - Macro used to select a character from basechars (i.e.,
 *                  mangle(n) will return the nth digit, modulo MANGLE_BASE).
 *
 * chartest       - array 0..255.  The index range is the set of all possible
 *                  values of a byte.  For each byte value, the content is a
 *                  two nibble pair.  See BASECHAR_MASK and ILLEGAL_MASK,
 *                  below.
 *
 * ct_initialized - False until the chartest array has been initialized via
 *                  a call to init_chartest().
 *
 * BASECHAR_MASK  - Masks the upper nibble of a one-byte value.
 *
 * ILLEGAL_MASK   - Masks the lower nibble of a one-byte value.
 *
 * isbasecahr()   - Given a character, check the chartest array to see
 *                  if that character is in the basechars set.  This is
 *                  faster than using strchr_m().
 *
 * isillegal()    - Given a character, check the chartest array to see
 *                  if that character is in the illegal characters set.
 *                  This is faster than using strchr_m().
 *
 * mangled_cache  - Cache header used for storing mangled -> original
 *                  reverse maps.
 *
 * mc_initialized - False until the mangled_cache structure has been
 *                  initialized via a call to reset_mangled_cache().
 *
 * MANGLED_CACHE_MAX_ENTRIES - Default maximum number of entries for the
 *                  cache.  A value of 0 indicates "infinite".
 *
 * MANGLED_CACHE_MAX_MEMORY  - Default maximum amount of memory for the
 *                  cache.  When the cache was kept as an array of 256
 *                  byte strings, the default cache size was 50 entries.
 *                  This required a fixed 12.5Kbytes of memory.  The
 *                  mangled stack parameter is no longer used (though
 *                  this might change).  We're now using a fixed 16Kbyte
 *                  maximum cache size.  This will probably be much more
 *                  than 50 entries.
 */

char magic_char = '~';

static char basechars[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_-!@#$%";
#define MANGLE_BASE       (sizeof(basechars)/sizeof(char)-1)

static unsigned char chartest[256]  = { 0 };
static BOOL          ct_initialized = False;

#define mangle(V) ((char)(basechars[(V) % MANGLE_BASE]))
#define BASECHAR_MASK 0xf0
#define ILLEGAL_MASK  0x0f
#define isbasechar(C) ( (chartest[ ((C) & 0xff) ]) & BASECHAR_MASK )
#define isillegal(C) ( (chartest[ ((C) & 0xff) ]) & ILLEGAL_MASK )

static ubi_cacheRoot mangled_cache[1] =  { { { 0, 0, 0, 0 }, 0, 0, 0, 0, 0, 0 } };
static BOOL          mc_initialized   = False;
#define MANGLED_CACHE_MAX_ENTRIES 1024
#define MANGLED_CACHE_MAX_MEMORY 0

/* -------------------------------------------------------------------------- **
 * External Variables...
 */

extern int case_default;    /* Are conforming 8.3 names all upper or lower?   */
extern BOOL case_mangle;    /* If true, all chars in 8.3 should be same case. */

/* -------------------------------------------------------------------- */

static NTSTATUS has_valid_chars(const smb_ucs2_t *s, BOOL allow_wildcards)
{
	if (!s || !*s)
		return NT_STATUS_INVALID_PARAMETER;

	/* CHECK: this should not be necessary if the ms wild chars
	   are not valid in valid.dat  --- simo */
	if (!allow_wildcards && ms_has_wild_w(s))
		return NT_STATUS_UNSUCCESSFUL;

	while (*s) {
		if(!isvalid83_w(*s))
			return NT_STATUS_UNSUCCESSFUL;
		s++;
	}

	return NT_STATUS_OK;
}

/* return False if something fail and
 * return 2 alloced unicode strings that contain prefix and extension
 */

static NTSTATUS mangle_get_prefix(const smb_ucs2_t *ucs2_string, smb_ucs2_t **prefix,
		smb_ucs2_t **extension, BOOL allow_wildcards)
{
	size_t ext_len;
	smb_ucs2_t *p;

	*extension = 0;
	*prefix = strdup_w(ucs2_string);
	if (!*prefix) {
		return NT_STATUS_NO_MEMORY;
	}
	if ((p = strrchr_w(*prefix, UCS2_CHAR('.')))) {
		ext_len = strlen_w(p+1);
		if ((ext_len > 0) && (ext_len < 4) && (p != *prefix) &&
		    (NT_STATUS_IS_OK(has_valid_chars(p+1,allow_wildcards)))) /* check extension */ {
			*p = 0;
			*extension = strdup_w(p+1);
			if (!*extension) {
				SAFE_FREE(*prefix);
				return NT_STATUS_NO_MEMORY;
			}
		}
	}
	return NT_STATUS_OK;
}

/* ************************************************************************** **
 * Return NT_STATUS_UNSUCCESSFUL if a name is a special msdos reserved name.
 *
 *  Input:  fname - String containing the name to be tested.
 *
 *  Output: NT_STATUS_UNSUCCESSFUL, if the name matches one of the list of reserved names.
 *
 *  Notes:  This is a static function called by is_8_3(), below.
 *
 * ************************************************************************** **
 */

static NTSTATUS is_valid_name(const smb_ucs2_t *fname, BOOL allow_wildcards)
{
	smb_ucs2_t *str, *p;
	NTSTATUS ret = NT_STATUS_OK;

	if (!fname || !*fname)
		return NT_STATUS_INVALID_PARAMETER;

	/* . and .. are valid names. */
	if (strcmp_wa(fname, ".")==0 || strcmp_wa(fname, "..")==0)
		return NT_STATUS_OK;

	/* Name cannot start with '.' */
	if (*fname == UCS2_CHAR('.'))
		return NT_STATUS_UNSUCCESSFUL;
	
	ret = has_valid_chars(fname, allow_wildcards);
	if (!NT_STATUS_IS_OK(ret))
		return ret;

	str = strdup_w(fname);
	p = strchr_w(str, UCS2_CHAR('.'));
	if (p && p[1] == UCS2_CHAR(0)) {
		/* Name cannot end in '.' */
		SAFE_FREE(str);
		return NT_STATUS_UNSUCCESSFUL;
	}
	if (p) *p = 0;
	strupper_w(str);
	p = &(str[1]);

	switch(str[0])
	{
	case UCS2_CHAR('A'):
		if(strcmp_wa(p, "UX") == 0)
			ret = NT_STATUS_UNSUCCESSFUL;
		break;
	case UCS2_CHAR('C'):
		if((strcmp_wa(p, "LOCK$") == 0)
		|| (strcmp_wa(p, "ON") == 0)
		|| (strcmp_wa(p, "OM1") == 0)
		|| (strcmp_wa(p, "OM2") == 0)
		|| (strcmp_wa(p, "OM3") == 0)
		|| (strcmp_wa(p, "OM4") == 0)
		)
			ret = NT_STATUS_UNSUCCESSFUL;
		break;
	case UCS2_CHAR('L'):
		if((strcmp_wa(p, "PT1") == 0)
		|| (strcmp_wa(p, "PT2") == 0)
		|| (strcmp_wa(p, "PT3") == 0)
		)
			ret = NT_STATUS_UNSUCCESSFUL;
		break;
	case UCS2_CHAR('N'):
		if(strcmp_wa(p, "UL") == 0)
			ret = NT_STATUS_UNSUCCESSFUL;
		break;
	case UCS2_CHAR('P'):
		if(strcmp_wa(p, "RN") == 0)
			ret = NT_STATUS_UNSUCCESSFUL;
		break;
	default:
		break;
	}

	SAFE_FREE(str);
	return ret;
}

static NTSTATUS is_8_3_w(const smb_ucs2_t *fname, BOOL allow_wildcards)
{
	smb_ucs2_t *pref = 0, *ext = 0;
	size_t plen;
	NTSTATUS ret = NT_STATUS_UNSUCCESSFUL;

	if (!fname || !*fname)
		return NT_STATUS_INVALID_PARAMETER;

	if (strlen_w(fname) > 12)
		return NT_STATUS_UNSUCCESSFUL;
	
	if (strcmp_wa(fname, ".") == 0 || strcmp_wa(fname, "..") == 0)
		return NT_STATUS_OK;

	if (!NT_STATUS_IS_OK(is_valid_name(fname, allow_wildcards)))
		goto done;

	if (!NT_STATUS_IS_OK(mangle_get_prefix(fname, &pref, &ext, allow_wildcards)))
		goto done;
	plen = strlen_w(pref);

	if (strchr_wa(pref, '.'))
		goto done;
	if (plen < 1 || plen > 8)
		goto done;
	if (ext && (strlen_w(ext) > 3))
		goto done;

	ret = NT_STATUS_OK;

done:
	SAFE_FREE(pref);
	SAFE_FREE(ext);
	return ret;
}

static BOOL is_8_3(const char *fname, BOOL check_case, BOOL allow_wildcards)
{
	const char *f;
	smb_ucs2_t *ucs2name;
	NTSTATUS ret = NT_STATUS_UNSUCCESSFUL;

	if (!fname || !*fname)
		return False;
	if ((f = strrchr(fname, '/')) == NULL)
		f = fname;
	else
		f++;

	if (strlen(f) > 12)
		return False;
	
	ucs2name = acnv_uxu2(f);
	if (!ucs2name) {
		DEBUG(0,("is_8_3: internal error acnv_uxu2() failed!\n"));
		goto done;
	}

	ret = is_8_3_w(ucs2name, allow_wildcards);

done:
	SAFE_FREE(ucs2name);

	if (!NT_STATUS_IS_OK(ret)) { 
		return False;
	}
	
	return True;
}



/* -------------------------------------------------------------------------- **
 * Functions...
 */

/* ************************************************************************** **
 * Initialize the static character test array.
 *
 *  Input:  none
 *
 *  Output: none
 *
 *  Notes:  This function changes (loads) the contents of the <chartest>
 *          array.  The scope of <chartest> is this file.
 *
 * ************************************************************************** **
 */
static void init_chartest( void )
{
	const char          *illegalchars = "*\\/?<>|\":";
	const unsigned char *s;
  
	memset( (char *)chartest, '\0', 256 );

	for( s = (const unsigned char *)illegalchars; *s; s++ )
		chartest[*s] = ILLEGAL_MASK;

	for( s = (const unsigned char *)basechars; *s; s++ )
		chartest[*s] |= BASECHAR_MASK;

	ct_initialized = True;
}

/* ************************************************************************** **
 * Return True if the name *could be* a mangled name.
 *
 *  Input:  s - A path name - in UNIX pathname format.
 *
 *  Output: True if the name matches the pattern described below in the
 *          notes, else False.
 *
 *  Notes:  The input name is *not* tested for 8.3 compliance.  This must be
 *          done separately.  This function returns true if the name contains
 *          a magic character followed by excactly two characters from the
 *          basechars list (above), which in turn are followed either by the
 *          nul (end of string) byte or a dot (extension) or by a '/' (end of
 *          a directory name).
 *
 * ************************************************************************** **
 */
static BOOL is_mangled(const char *s)
{
	char *magic;

	if( !ct_initialized )
		init_chartest();

	magic = strchr_m( s, magic_char );
	while( magic && magic[1] && magic[2] ) {         /* 3 chars, 1st is magic. */
		if( ('.' == magic[3] || '/' == magic[3] || !(magic[3]))          /* Ends with '.' or nul or '/' ?  */
				&& isbasechar( toupper(magic[1]) )           /* is 2nd char basechar?  */
				&& isbasechar( toupper(magic[2]) ) )         /* is 3rd char basechar?  */
			return( True );                           /* If all above, then true, */
		magic = strchr_m( magic+1, magic_char );      /*    else seek next magic. */
	}
	return( False );
}

/* ************************************************************************** **
 * Compare two cache keys and return a value indicating their ordinal
 * relationship.
 *
 *  Input:  ItemPtr - Pointer to a comparison key.  In this case, this will
 *                    be a mangled name string.
 *          NodePtr - Pointer to a node in the cache.  The node structure
 *                    will be followed in memory by a mangled name string.
 *
 *  Output: A signed integer, as follows:
 *            (x < 0)  <==> Key1 less than Key2
 *            (x == 0) <==> Key1 equals Key2
 *            (x > 0)  <==> Key1 greater than Key2
 *
 *  Notes:  This is a ubiqx-style comparison routine.  See ubi_BinTree for
 *          more info.
 *
 * ************************************************************************** **
 */
static signed int cache_compare( ubi_btItemPtr ItemPtr, ubi_btNodePtr NodePtr )
{
	char *Key1 = (char *)ItemPtr;
	char *Key2 = (char *)(((ubi_cacheEntryPtr)NodePtr) + 1);

	return( StrCaseCmp( Key1, Key2 ) );
}

/* ************************************************************************** **
 * Free a cache entry.
 *
 *  Input:  WarrenZevon - Pointer to the entry that is to be returned to
 *                        Nirvana.
 *  Output: none.
 *
 *  Notes:  This function gets around the possibility that the standard
 *          free() function may be implemented as a macro, or other evil
 *          subversions (oh, so much fun).
 *
 * ************************************************************************** **
 */
static void cache_free_entry( ubi_trNodePtr WarrenZevon )
{
	ZERO_STRUCTP(WarrenZevon);
	SAFE_FREE( WarrenZevon );
}

/* ************************************************************************** **
 * Initializes or clears the mangled cache.
 *
 *  Input:  none.
 *  Output: none.
 *
 *  Notes:  There is a section below that is commented out.  It shows how
 *          one might use lp_ calls to set the maximum memory and entry size
 *          of the cache.  You might also want to remove the constants used
 *          in ubi_cacheInit() and replace them with lp_ calls.  If so, then
 *          the calls to ubi_cacheSetMax*() would be moved into the else
 *          clause.  Another option would be to pass in the max_entries and
 *          max_memory values as parameters.  crh 09-Apr-1998.
 *
 * ************************************************************************** **
 */

static void mangle_reset( void )
{
	if( !mc_initialized ) {
		(void)ubi_cacheInit( mangled_cache,
				cache_compare,
				cache_free_entry,
				MANGLED_CACHE_MAX_ENTRIES,
				MANGLED_CACHE_MAX_MEMORY );
		mc_initialized = True;
	} else {
		(void)ubi_cacheClear( mangled_cache );
	}

	/*
	(void)ubi_cacheSetMaxEntries( mangled_cache, lp_mangled_cache_entries() );
	(void)ubi_cacheSetMaxMemory(  mangled_cache, lp_mangled_cache_memory() );
	*/
}

/* ************************************************************************** **
 * Add a mangled name into the cache.
 *
 *  Notes:  If the mangled cache has not been initialized, then the
 *          function will simply fail.  It could initialize the cache,
 *          but that's not the way it was done before I changed the
 *          cache mechanism, so I'm sticking with the old method.
 *
 *          If the extension of the raw name maps directly to the
 *          extension of the mangled name, then we'll store both names
 *          *without* extensions.  That way, we can provide consistent
 *          reverse mangling for all names that match.  The test here is
 *          a bit more careful than the one done in earlier versions of
 *          mangle.c:
 *
 *            - the extension must exist on the raw name,
 *            - it must be all lower case
 *            - it must match the mangled extension (to prove that no
 *              mangling occurred).
 *
 *  crh 07-Apr-1998
 *
 * ************************************************************************** **
 */
static void cache_mangled_name( char *mangled_name, char *raw_name )
{
	ubi_cacheEntryPtr new_entry;
	char             *s1;
	char             *s2;
	size_t               mangled_len;
	size_t               raw_len;
	size_t               i;

	/* If the cache isn't initialized, give up. */
	if( !mc_initialized )
		return;

	/* Init the string lengths. */
	mangled_len = strlen( mangled_name );
	raw_len     = strlen( raw_name );

	/* See if the extensions are unmangled.  If so, store the entry
	 * without the extension, thus creating a "group" reverse map.
	 */
	s1 = strrchr( mangled_name, '.' );
	if( s1 && (s2 = strrchr( raw_name, '.' )) ) {
		i = 1;
		while( s1[i] && (tolower( s1[i] ) == s2[i]) )
			i++;
		if( !s1[i] && !s2[i] ) {
			mangled_len -= i;
			raw_len     -= i;
		}
	}

	/* Allocate a new cache entry.  If the allocation fails, just return. */
	i = sizeof( ubi_cacheEntry ) + mangled_len + raw_len + 2;
	new_entry = malloc( i );
	if( !new_entry )
		return;

	/* Fill the new cache entry, and add it to the cache. */
	s1 = (char *)(new_entry + 1);
	s2 = (char *)&(s1[mangled_len + 1]);
	safe_strcpy( s1, mangled_name, mangled_len );
	safe_strcpy( s2, raw_name,     raw_len );
	ubi_cachePut( mangled_cache, i, new_entry, s1 );
}

/* ************************************************************************** **
 * Check for a name on the mangled name stack
 *
 *  Input:  s - Input *and* output string buffer.
 *
 *  Output: True if the name was found in the cache, else False.
 *
 *  Notes:  If a reverse map is found, the function will overwrite the string
 *          space indicated by the input pointer <s>.  This is frightening.
 *          It should be rewritten to return NULL if the long name was not
 *          found, and a pointer to the long name if it was found.
 *
 * ************************************************************************** **
 */

static BOOL check_cache( char *s )
{
	ubi_cacheEntryPtr FoundPtr;
	char             *ext_start = NULL;
	char             *found_name;
	char             *saved_ext = NULL;

	/* If the cache isn't initialized, give up. */
	if( !mc_initialized )
		return( False );

	FoundPtr = ubi_cacheGet( mangled_cache, (ubi_trItemPtr)s );

	/* If we didn't find the name *with* the extension, try without. */
	if( !FoundPtr ) {
		ext_start = strrchr( s, '.' );
		if( ext_start ) {
			if((saved_ext = strdup(ext_start)) == NULL)
				return False;

			*ext_start = '\0';
			FoundPtr = ubi_cacheGet( mangled_cache, (ubi_trItemPtr)s );
			/* 
			 * At this point s is the name without the
			 * extension. We re-add the extension if saved_ext
			 * is not null, before freeing saved_ext.
			 */
		}
	}

	/* Okay, if we haven't found it we're done. */
	if( !FoundPtr ) {
		if(saved_ext) {
			/* Replace the saved_ext as it was truncated. */
			(void)pstrcat( s, saved_ext );
			SAFE_FREE(saved_ext);
		}
		return( False );
	}

	/* If we *did* find it, we need to copy it into the string buffer. */
	found_name = (char *)(FoundPtr + 1);
	found_name += (strlen( found_name ) + 1);

	(void)pstrcpy( s, found_name );
	if( saved_ext ) {
		/* Replace the saved_ext as it was truncated. */
		(void)pstrcat( s, saved_ext );
		SAFE_FREE(saved_ext);
	}

	return( True );
}

/*****************************************************************************
 * do the actual mangling to 8.3 format
 * the buffer must be able to hold 13 characters (including the null)
 *****************************************************************************
 */
static void to_8_3(char *s)
{
	int csum;
	char *p;
	char extension[4];
	char base[9];
	int baselen = 0;
	int extlen = 0;

	extension[0] = 0;
	base[0] = 0;

	p = strrchr(s,'.');  
	if( p && (strlen(p+1) < (size_t)4) ) {
		BOOL all_normal = ( strisnormal(p+1) ); /* XXXXXXXXX */

		if( all_normal && p[1] != 0 ) {
			*p = 0;
			csum = str_checksum( s );
			*p = '.';
		} else
			csum = str_checksum(s);
	} else
		csum = str_checksum(s);

	strupper( s );

	if( p ) {
		if( p == s )
			safe_strcpy( extension, "___", 3 );
		else {
			*p++ = 0;
			while( *p && extlen < 3 ) {
				if ( *p != '.') {
					extension[extlen++] = p[0];
				}
				p++;
			}
			extension[extlen] = 0;
		}
	}
  
	p = s;

	while( *p && baselen < 5 ) {
		if (*p != '.') {
			base[baselen++] = p[0];
		}
		p++;
	}
	base[baselen] = 0;
  
	csum = csum % (MANGLE_BASE*MANGLE_BASE);
  
	(void)slprintf(s, 12, "%s%c%c%c",
		base, magic_char, mangle( csum/MANGLE_BASE ), mangle( csum ) );
  
	if( *extension ) {
		(void)pstrcat( s, "." );
		(void)pstrcat( s, extension );
	}
}

/*****************************************************************************
 * Convert a filename to DOS format.  Return True if successful.
 *
 *  Input:  OutName - Source *and* destination buffer. 
 *
 *                    NOTE that OutName must point to a memory space that
 *                    is at least 13 bytes in size!
 *
 *          need83  - If False, name mangling will be skipped unless the
 *                    name contains illegal characters.  Mapping will still
 *                    be done, if appropriate.  This is probably used to
 *                    signal that a client does not require name mangling,
 *                    thus skipping the name mangling even on shares which
 *                    have name-mangling turned on.
 *          cache83 - If False, the mangled name cache will not be updated.
 *                    This is usually used to prevent that we overwrite
 *                    a conflicting cache entry prematurely, i.e. before
 *                    we know whether the client is really interested in the
 *                    current name.  (See PR#13758).  UKD.
 *
 *  Output: Returns False only if the name wanted mangling but the share does
 *          not have name mangling turned on.
 *
 * ****************************************************************************
 */

static void name_map(char *OutName, BOOL need83, BOOL cache83)
{
	smb_ucs2_t *OutName_ucs2;
	DEBUG(5,("name_map( %s, need83 = %s, cache83 = %s)\n", OutName,
		 need83 ? "True" : "False", cache83 ? "True" : "False"));
	
	if (push_ucs2_allocate(&OutName_ucs2, OutName) == (size_t)-1) {
		DEBUG(0, ("push_ucs2_allocate failed!\n"));
		return;
	}

	if( !need83 && !NT_STATUS_IS_OK(is_valid_name(OutName_ucs2, False)))
		need83 = True;

	/* check if it's already in 8.3 format */
	if (need83 && !NT_STATUS_IS_OK(is_8_3_w(OutName_ucs2, False))) {
		char *tmp = NULL; 

		/* mangle it into 8.3 */
		if (cache83)
			tmp = strdup(OutName);

		to_8_3(OutName);

		if(tmp != NULL) {
			cache_mangled_name(OutName, tmp);
			SAFE_FREE(tmp);
		}
	}

	DEBUG(5,("name_map() ==> [%s]\n", OutName));
	SAFE_FREE(OutName_ucs2);
}

/*
  the following provides the abstraction layer to make it easier
  to drop in an alternative mangling implementation
*/
static struct mangle_fns mangle_fns = {
	is_mangled,
	is_8_3,
	mangle_reset,
	check_cache,
	name_map
};

/* return the methods for this mangling implementation */
struct mangle_fns *mangle_hash_init(void)
{
	mangle_reset();

	return &mangle_fns;
}