source: branches/samba-3.2.x/source/lib/util_unistr.c@ 201

/* 
   Unix SMB/CIFS implementation.
   Samba utility functions
   Copyright (C) Andrew Tridgell 1992-2001
   Copyright (C) Simo Sorce 2001
   Copyright (C) Jeremy Allison 2005
   
   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

#ifndef MAXUNI
#define MAXUNI 1024
#endif

/* these 3 tables define the unicode case handling.  They are loaded
   at startup either via mmap() or read() from the lib directory */
static smb_ucs2_t *upcase_table;
static smb_ucs2_t *lowcase_table;
static uint8 *valid_table;
static bool upcase_table_use_unmap;
static bool lowcase_table_use_unmap;
static bool valid_table_use_unmap;
static bool initialized;

/**
 * Destroy global objects allocated by load_case_tables()
 **/
void gfree_case_tables(void)
{
        if ( upcase_table ) {
                if ( upcase_table_use_unmap )
                        unmap_file(upcase_table, 0x20000);
                else
                        SAFE_FREE(upcase_table);
        }

        if ( lowcase_table ) {
                if ( lowcase_table_use_unmap )
                        unmap_file(lowcase_table, 0x20000);
                else
                        SAFE_FREE(lowcase_table);
        }

        if ( valid_table ) {
                if ( valid_table_use_unmap )
                        unmap_file(valid_table, 0x10000);
                else
                        SAFE_FREE(valid_table);
        }
        initialized = false;
}

/**
 * Load or generate the case handling tables.
 *
 * The case tables are defined in UCS2 and don't depend on any
 * configured parameters, so they never need to be reloaded.
 **/

void load_case_tables(void)
{
        char *old_locale = NULL, *saved_locale = NULL;
        int i;
        TALLOC_CTX *frame = NULL;

        if (initialized) {
                return;
        }
        initialized = true;

        frame = talloc_stackframe();

        upcase_table = (smb_ucs2_t *)map_file(data_path("upcase.dat"),
                                              0x20000);
        upcase_table_use_unmap = ( upcase_table != NULL );

        lowcase_table = (smb_ucs2_t *)map_file(data_path("lowcase.dat"),
                                               0x20000);
        lowcase_table_use_unmap = ( lowcase_table != NULL );

#ifdef HAVE_SETLOCALE
        /* Get the name of the current locale.  */
        old_locale = setlocale(LC_ALL, NULL);

        if (old_locale) {
                /* Save it as it is in static storage. */
                saved_locale = SMB_STRDUP(old_locale);
        }

        /* We set back the locale to C to get ASCII-compatible toupper/lower functions. */
        setlocale(LC_ALL, "C");
#endif

        /* we would like Samba to limp along even if these tables are
           not available */
        if (!upcase_table) {
                DEBUG(1,("creating lame upcase table\n"));
                upcase_table = (smb_ucs2_t *)SMB_MALLOC(0x20000);
                for (i=0;i<0x10000;i++) {
                        smb_ucs2_t v;
                        SSVAL(&v, 0, i);
                        upcase_table[v] = i;
                }
                for (i=0;i<256;i++) {
                        smb_ucs2_t v;
                        SSVAL(&v, 0, UCS2_CHAR(i));
                        upcase_table[v] = UCS2_CHAR(islower(i)?toupper(i):i);
                }
        }

        if (!lowcase_table) {
                DEBUG(1,("creating lame lowcase table\n"));
                lowcase_table = (smb_ucs2_t *)SMB_MALLOC(0x20000);
                for (i=0;i<0x10000;i++) {
                        smb_ucs2_t v;
                        SSVAL(&v, 0, i);
                        lowcase_table[v] = i;
                }
                for (i=0;i<256;i++) {
                        smb_ucs2_t v;
                        SSVAL(&v, 0, UCS2_CHAR(i));
                        lowcase_table[v] = UCS2_CHAR(isupper(i)?tolower(i):i);
                }
        }

#ifdef HAVE_SETLOCALE
        /* Restore the old locale. */
        if (saved_locale) {
                setlocale (LC_ALL, saved_locale);
                SAFE_FREE(saved_locale);
        }
#endif
        TALLOC_FREE(frame);
}

static int check_dos_char_slowly(smb_ucs2_t c)
{
        char buf[10];
        smb_ucs2_t c2 = 0;
        int len1, len2;

        len1 = convert_string(CH_UTF16LE, CH_DOS, &c, 2, buf, sizeof(buf),False);
        if (len1 == 0) {
                return 0;
        }
        len2 = convert_string(CH_DOS, CH_UTF16LE, buf, len1, &c2, 2,False);
        if (len2 != 2) {
                return 0;
        }
        return (c == c2);
}

/**
 * Load the valid character map table from <tt>valid.dat</tt> or
 * create from the configured codepage.
 *
 * This function is called whenever the configuration is reloaded.
 * However, the valid character table is not changed if it's loaded
 * from a file, because we can't unmap files.
 **/

void init_valid_table(void)
{
        static int mapped_file;
        int i;
        const char *allowed = ".!#$%&'()_-@^`~";
        uint8 *valid_file;

        if (mapped_file) {
                /* Can't unmap files, so stick with what we have */
                return;
        }

        valid_file = (uint8 *)map_file(data_path("valid.dat"), 0x10000);
        if (valid_file) {
                valid_table = valid_file;
                mapped_file = 1;
                valid_table_use_unmap = True;
                return;
        }

        /* Otherwise, we're using a dynamically created valid_table.
         * It might need to be regenerated if the code page changed.
         * We know that we're not using a mapped file, so we can
         * free() the old one. */
        SAFE_FREE(valid_table);

        /* use free rather than unmap */
        valid_table_use_unmap = False;

        DEBUG(2,("creating default valid table\n"));
        valid_table = (uint8 *)SMB_MALLOC(0x10000);
        SMB_ASSERT(valid_table != NULL);
        for (i=0;i<128;i++) {
                valid_table[i] = isalnum(i) || strchr(allowed,i);
        }

        lazy_initialize_conv();

        for (;i<0x10000;i++) {
                smb_ucs2_t c;
                SSVAL(&c, 0, i);
                valid_table[i] = check_dos_char_slowly(c);
        }
}

/*******************************************************************
 Write a string in (little-endian) unicode format. src is in
 the current DOS codepage. len is the length in bytes of the
 string pointed to by dst.

 if null_terminate is True then null terminate the packet (adds 2 bytes)

 the return value is the length in bytes consumed by the string, including the
 null termination if applied
********************************************************************/

size_t dos_PutUniCode(char *dst,const char *src, size_t len, bool null_terminate)
{
        int flags = null_terminate ? STR_UNICODE|STR_NOALIGN|STR_TERMINATE
                                   : STR_UNICODE|STR_NOALIGN;
        return push_ucs2(NULL, dst, src, len, flags);
}


/*******************************************************************
 Skip past a unicode string, but not more than len. Always move
 past a terminating zero if found.
********************************************************************/

char *skip_unibuf(char *src, size_t len)
{
        char *srcend = src + len;

        while (src < srcend && SVAL(src,0)) {
                src += 2;
        }

        if(!SVAL(src,0)) {
                src += 2;
        }

        return src;
}

/* Copy a string from little-endian or big-endian unicode source (depending
 * on flags) to internal samba format destination
 */ 

int rpcstr_pull(char* dest, void *src, int dest_len, int src_len, int flags)
{
        if (!src) {
                dest[0] = 0;
                return 0;
        }
        if(dest_len==-1) {
                dest_len=MAXUNI-3;
        }
        return pull_ucs2(NULL, dest, src, dest_len, src_len, flags|STR_UNICODE|STR_NOALIGN);
}

/* Copy a string from little-endian or big-endian unicode source (depending
 * on flags) to internal samba format destination. Allocates on talloc ctx.
 */

int rpcstr_pull_talloc(TALLOC_CTX *ctx,
                        char **dest,
                        void *src,
                        int src_len,
                        int flags)
{
        return pull_ucs2_base_talloc(ctx,
                        NULL,
                        dest,
                        src,
                        src_len,
                        flags|STR_UNICODE|STR_NOALIGN);

}

/* Copy a string from a unistr2 source to internal samba format
   destination.  Use this instead of direct calls to rpcstr_pull() to avoid
   having to determine whether the source string is null terminated. */

int rpcstr_pull_unistr2_fstring(char *dest, UNISTR2 *src)
{
        return pull_ucs2(NULL, dest, src->buffer, sizeof(fstring),
                         src->uni_str_len * 2, 0);
}

/* Helper function to return a talloc'ed string. I have implemented it with a
 * copy because I don't really know how pull_ucs2 and friends calculate the
 * target size. If this turns out to be a major bottleneck someone with deeper
 * multi-byte knowledge needs to revisit this.
 * I just did (JRA :-). No longer uses copy.
 * My (VL) use is dsr_getdcname, which returns 6 strings, the alternative would
 * have been to manually talloc_strdup them in rpc_client/cli_netlogon.c.
 */

char *rpcstr_pull_unistr2_talloc(TALLOC_CTX *ctx, const UNISTR2 *src)
{
        char *dest = NULL;
        size_t dest_len = convert_string_talloc(ctx,
                                CH_UTF16LE,
                                CH_UNIX,
                                src->buffer,
                                src->uni_str_len * 2,
                                (void *)&dest,
                                true);
        if (dest_len == (size_t)-1) {
                return NULL;
        }

        /* Ensure we're returning a null terminated string. */
        if (dest_len) {
                /* Did we already process the terminating zero ? */
                if (dest[dest_len-1] != 0) {
                        size_t size = talloc_get_size(dest);
                        /* Have we got space to append the '\0' ? */
                        if (size <= dest_len) {
                                /* No, realloc. */
                                dest = TALLOC_REALLOC_ARRAY(ctx, dest, char,
                                                dest_len+1);
                                if (!dest) {
                                        /* talloc fail. */
                                        dest_len = (size_t)-1;
                                        return NULL;
                                }
                        }
                        /* Yay - space ! */
                        dest[dest_len] = '\0';
                        dest_len++;
                }
        } else if (dest) {
                dest[0] = 0;
        }

        return dest;
}

/* Converts a string from internal samba format to unicode
 */

int rpcstr_push(void *dest, const char *src, size_t dest_len, int flags)
{
        return push_ucs2(NULL, dest, src, dest_len, flags|STR_UNICODE|STR_NOALIGN);
}

/* Converts a string from internal samba format to unicode. Always terminates.
 * Actually just a wrapper round push_ucs2_talloc().
 */

int rpcstr_push_talloc(TALLOC_CTX *ctx, smb_ucs2_t **dest, const char *src)
{
        return push_ucs2_talloc(ctx, dest, src);
}

/*******************************************************************
 Convert a (little-endian) UNISTR2 structure to an ASCII string.
********************************************************************/

void unistr2_to_ascii(char *dest, const UNISTR2 *str, size_t maxlen)
{
        if ((str == NULL) || (str->uni_str_len == 0)) {
                *dest='\0';
                return;
        }
        pull_ucs2(NULL, dest, str->buffer, maxlen, str->uni_str_len*2, STR_NOALIGN);
}

#if 0
/*******************************************************************
 Convert a (little-endian) UNISTR3 structure to an ASCII string.
********************************************************************/

void unistr3_to_ascii(char *dest, const UNISTR3 *str, size_t maxlen)
{
        if ((str == NULL) || (str->uni_str_len == 0)) {
                *dest='\0';
                return;
        }
        pull_ucs2(NULL, dest, str->str.buffer, maxlen, str->uni_str_len*2,
                  STR_NOALIGN);
}
#endif

/*******************************************************************
 Duplicate a UNISTR2 string into a null terminated char*
 using a talloc context.
********************************************************************/

char *unistr2_to_ascii_talloc(TALLOC_CTX *ctx, const UNISTR2 *str)
{
        char *s = NULL;

        if (!str || !str->buffer) {
                return NULL;
        }
        if (pull_ucs2_base_talloc(ctx,
                                NULL,
                                &s,
                                str->buffer,
                                str->uni_str_len*2,
                                STR_NOALIGN) == (size_t)-1) {
                return NULL;
        }
        return s;
}

/*******************************************************************
 Return a string for displaying a UNISTR2. Guarentees to return a
 valid string - "" if nothing else.
 Changed to use talloc_tos() under the covers.... JRA.
********************************************************************/

const char *unistr2_static(const UNISTR2 *str)
{
        char *dest = NULL;

        if ((str == NULL) || (str->uni_str_len == 0)) {
                return "";
        }

        dest = unistr2_to_ascii_talloc(talloc_tos(), str);
        if (!dest) {
                return "";
        }

        return dest;
}

/*******************************************************************
 Convert a wchar to upper case.
********************************************************************/

smb_ucs2_t toupper_w(smb_ucs2_t val)
{
        return upcase_table[SVAL(&val,0)];
}

/*******************************************************************
 Convert a wchar to lower case.
********************************************************************/

smb_ucs2_t tolower_w( smb_ucs2_t val )
{
        return lowcase_table[SVAL(&val,0)];
}

/*******************************************************************
 Determine if a character is lowercase.
********************************************************************/

bool islower_w(smb_ucs2_t c)
{
        return upcase_table[SVAL(&c,0)] != c;
}

/*******************************************************************
 Determine if a character is uppercase.
********************************************************************/

bool isupper_w(smb_ucs2_t c)
{
        return lowcase_table[SVAL(&c,0)] != c;
}

/*******************************************************************
 Determine if a character is valid in a 8.3 name.
********************************************************************/

bool isvalid83_w(smb_ucs2_t c)
{
        return valid_table[SVAL(&c,0)] != 0;
}

/*******************************************************************
 Count the number of characters in a smb_ucs2_t string.
********************************************************************/

size_t strlen_w(const smb_ucs2_t *src)
{
        size_t len;
        smb_ucs2_t c;

        for(len = 0; *(COPY_UCS2_CHAR(&c,src)); src++, len++) {
                ;
        }

        return len;
}

/*******************************************************************
 Count up to max number of characters in a smb_ucs2_t string.
********************************************************************/

size_t strnlen_w(const smb_ucs2_t *src, size_t max)
{
        size_t len;
        smb_ucs2_t c;

        for(len = 0; (len < max) && *(COPY_UCS2_CHAR(&c,src)); src++, len++) {
                ;
        }

        return len;
}

/*******************************************************************
 Wide strchr().
********************************************************************/

smb_ucs2_t *strchr_w(const smb_ucs2_t *s, smb_ucs2_t c)
{
        smb_ucs2_t cp;
        while (*(COPY_UCS2_CHAR(&cp,s))) {
                if (c == cp) {
                        return (smb_ucs2_t *)s;
                }
                s++;
        }
        if (c == cp) {
                return (smb_ucs2_t *)s;
        }

        return NULL;
}

smb_ucs2_t *strchr_wa(const smb_ucs2_t *s, char c)
{
        return strchr_w(s, UCS2_CHAR(c));
}

/*******************************************************************
 Wide strrchr().
********************************************************************/

smb_ucs2_t *strrchr_w(const smb_ucs2_t *s, smb_ucs2_t c)
{
        smb_ucs2_t cp;
        const smb_ucs2_t *p = s;
        int len = strlen_w(s);

        if (len == 0) {
                return NULL;
        }
        p += (len - 1);
        do {
                if (c == *(COPY_UCS2_CHAR(&cp,p))) {
                        return (smb_ucs2_t *)p;
                }
        } while (p-- != s);
        return NULL;
}

/*******************************************************************
 Wide version of strrchr that returns after doing strrchr 'n' times.
********************************************************************/

smb_ucs2_t *strnrchr_w(const smb_ucs2_t *s, smb_ucs2_t c, unsigned int n)
{
        smb_ucs2_t cp;
        const smb_ucs2_t *p = s;
        int len = strlen_w(s);

        if (len == 0 || !n) {
                return NULL;
        }
        p += (len - 1);
        do {
                if (c == *(COPY_UCS2_CHAR(&cp,p))) {
                        n--;
                }

                if (!n) {
                        return (smb_ucs2_t *)p;
                }
        } while (p-- != s);
        return NULL;
}

/*******************************************************************
 Wide strstr().
********************************************************************/

smb_ucs2_t *strstr_w(const smb_ucs2_t *s, const smb_ucs2_t *ins)
{
        smb_ucs2_t *r;
        size_t inslen;

        if (!s || !*s || !ins || !*ins) {
                return NULL;
        }

        inslen = strlen_w(ins);
        r = (smb_ucs2_t *)s;

        while ((r = strchr_w(r, *ins))) {
                if (strncmp_w(r, ins, inslen) == 0) {
                        return r;
                }
                r++;
        }

        return NULL;
}

/*******************************************************************
 Convert a string to lower case.
 return True if any char is converted
********************************************************************/

bool strlower_w(smb_ucs2_t *s)
{
        smb_ucs2_t cp;
        bool ret = False;

        while (*(COPY_UCS2_CHAR(&cp,s))) {
                smb_ucs2_t v = tolower_w(cp);
                if (v != cp) {
                        COPY_UCS2_CHAR(s,&v);
                        ret = True;
                }
                s++;
        }
        return ret;
}

/*******************************************************************
 Convert a string to upper case.
 return True if any char is converted
********************************************************************/

bool strupper_w(smb_ucs2_t *s)
{
        smb_ucs2_t cp;
        bool ret = False;
        while (*(COPY_UCS2_CHAR(&cp,s))) {
                smb_ucs2_t v = toupper_w(cp);
                if (v != cp) {
                        COPY_UCS2_CHAR(s,&v);
                        ret = True;
                }
                s++;
        }
        return ret;
}

/*******************************************************************
 Convert a string to "normal" form.
********************************************************************/

void strnorm_w(smb_ucs2_t *s, int case_default)
{
        if (case_default == CASE_UPPER) {
                strupper_w(s);
        } else {
                strlower_w(s);
        }
}

int strcmp_w(const smb_ucs2_t *a, const smb_ucs2_t *b)
{
        smb_ucs2_t cpa, cpb;

        while ((*(COPY_UCS2_CHAR(&cpb,b))) && (*(COPY_UCS2_CHAR(&cpa,a)) == cpb)) {
                a++;
                b++;
        }
        return (*(COPY_UCS2_CHAR(&cpa,a)) - *(COPY_UCS2_CHAR(&cpb,b)));
        /* warning: if *a != *b and both are not 0 we return a random
                greater or lesser than 0 number not realted to which
                string is longer */
}

int strncmp_w(const smb_ucs2_t *a, const smb_ucs2_t *b, size_t len)
{
        smb_ucs2_t cpa, cpb;
        size_t n = 0;

        while ((n < len) && (*(COPY_UCS2_CHAR(&cpb,b))) && (*(COPY_UCS2_CHAR(&cpa,a)) == cpb)) {
                a++;
                b++;
                n++;
        }
        return (len - n)?(*(COPY_UCS2_CHAR(&cpa,a)) - *(COPY_UCS2_CHAR(&cpb,b))):0;
}

/*******************************************************************
 Case insensitive string comparison.
********************************************************************/

int strcasecmp_w(const smb_ucs2_t *a, const smb_ucs2_t *b)
{
        smb_ucs2_t cpa, cpb;

        while ((*COPY_UCS2_CHAR(&cpb,b)) && toupper_w(*(COPY_UCS2_CHAR(&cpa,a))) == toupper_w(cpb)) {
                a++;
                b++;
        }
        return (tolower_w(*(COPY_UCS2_CHAR(&cpa,a))) - tolower_w(*(COPY_UCS2_CHAR(&cpb,b))));
}

/*******************************************************************
 Case insensitive string comparison, length limited.
********************************************************************/

int strncasecmp_w(const smb_ucs2_t *a, const smb_ucs2_t *b, size_t len)
{
        smb_ucs2_t cpa, cpb;
        size_t n = 0;

        while ((n < len) && *COPY_UCS2_CHAR(&cpb,b) && (toupper_w(*(COPY_UCS2_CHAR(&cpa,a))) == toupper_w(cpb))) {
                a++;
                b++;
                n++;
        }
        return (len - n)?(tolower_w(*(COPY_UCS2_CHAR(&cpa,a))) - tolower_w(*(COPY_UCS2_CHAR(&cpb,b)))):0;
}

/*******************************************************************
 Compare 2 strings.
********************************************************************/

bool strequal_w(const smb_ucs2_t *s1, const smb_ucs2_t *s2)
{
        if (s1 == s2) {
                return(True);
        }
        if (!s1 || !s2) {
                return(False);
        }
  
        return(strcasecmp_w(s1,s2)==0);
}

/*******************************************************************
 Compare 2 strings up to and including the nth char.
******************************************************************/

bool strnequal_w(const smb_ucs2_t *s1,const smb_ucs2_t *s2,size_t n)
{
        if (s1 == s2) {
                return(True);
        }
        if (!s1 || !s2 || !n) {
                return(False);
        }
  
        return(strncasecmp_w(s1,s2,n)==0);
}

/*******************************************************************
 Duplicate string.
********************************************************************/

smb_ucs2_t *strdup_w(const smb_ucs2_t *src)
{
        return strndup_w(src, 0);
}

/* if len == 0 then duplicate the whole string */

smb_ucs2_t *strndup_w(const smb_ucs2_t *src, size_t len)
{
        smb_ucs2_t *dest;
        
        if (!len) {
                len = strlen_w(src);
        }
        dest = SMB_MALLOC_ARRAY(smb_ucs2_t, len + 1);
        if (!dest) {
                DEBUG(0,("strdup_w: out of memory!\n"));
                return NULL;
        }

        memcpy(dest, src, len * sizeof(smb_ucs2_t));
        dest[len] = 0;
        return dest;
}

/*******************************************************************
 Copy a string with max len.
********************************************************************/

smb_ucs2_t *strncpy_w(smb_ucs2_t *dest, const smb_ucs2_t *src, const size_t max)
{
        smb_ucs2_t cp;
        size_t len;
        
        if (!dest || !src) {
                return NULL;
        }
        
        for (len = 0; (*COPY_UCS2_CHAR(&cp,(src+len))) && (len < max); len++) {
                cp = *COPY_UCS2_CHAR(dest+len,src+len);
        }
        cp = 0;
        for ( /*nothing*/ ; len < max; len++ ) {
                cp = *COPY_UCS2_CHAR(dest+len,&cp);
        }
        
        return dest;
}

/*******************************************************************
 Append a string of len bytes and add a terminator.
********************************************************************/

smb_ucs2_t *strncat_w(smb_ucs2_t *dest, const smb_ucs2_t *src, const size_t max)
{       
        size_t start;
        size_t len;     
        smb_ucs2_t z = 0;

        if (!dest || !src) {
                return NULL;
        }
        
        start = strlen_w(dest);
        len = strnlen_w(src, max);

        memcpy(&dest[start], src, len*sizeof(smb_ucs2_t));                      
        z = *COPY_UCS2_CHAR(dest+start+len,&z);

        return dest;
}

smb_ucs2_t *strcat_w(smb_ucs2_t *dest, const smb_ucs2_t *src)
{       
        size_t start;
        size_t len;     
        smb_ucs2_t z = 0;
        
        if (!dest || !src) {
                return NULL;
        }
        
        start = strlen_w(dest);
        len = strlen_w(src);

        memcpy(&dest[start], src, len*sizeof(smb_ucs2_t));                      
        z = *COPY_UCS2_CHAR(dest+start+len,&z);
        
        return dest;
}


/*******************************************************************
 Replace any occurence of oldc with newc in unicode string.
********************************************************************/

void string_replace_w(smb_ucs2_t *s, smb_ucs2_t oldc, smb_ucs2_t newc)
{
        smb_ucs2_t cp;

        for(;*(COPY_UCS2_CHAR(&cp,s));s++) {
                if(cp==oldc) {
                        COPY_UCS2_CHAR(s,&newc);
                }
        }
}

/*******************************************************************
 Trim unicode string.
********************************************************************/

bool trim_string_w(smb_ucs2_t *s, const smb_ucs2_t *front,
                                  const smb_ucs2_t *back)
{
        bool ret = False;
        size_t len, front_len, back_len;

        if (!s) {
                return False;
        }

        len = strlen_w(s);

        if (front && *front) {
                front_len = strlen_w(front);
                while (len && strncmp_w(s, front, front_len) == 0) {
                        memmove(s, (s + front_len), (len - front_len + 1) * sizeof(smb_ucs2_t));
                        len -= front_len;
                        ret = True;
                }
        }
        
        if (back && *back) {
                back_len = strlen_w(back);
                while (len && strncmp_w((s + (len - back_len)), back, back_len) == 0) {
                        s[len - back_len] = 0;
                        len -= back_len;
                        ret = True;
                }
        }

        return ret;
}

/*
  The *_wa() functions take a combination of 7 bit ascii
  and wide characters They are used so that you can use string
  functions combining C string constants with ucs2 strings

  The char* arguments must NOT be multibyte - to be completely sure
  of this only pass string constants */

int strcmp_wa(const smb_ucs2_t *a, const char *b)
{
        smb_ucs2_t cp = 0;

        while (*b && *(COPY_UCS2_CHAR(&cp,a)) == UCS2_CHAR(*b)) {
                a++;
                b++;
        }
        return (*(COPY_UCS2_CHAR(&cp,a)) - UCS2_CHAR(*b));
}

int strncmp_wa(const smb_ucs2_t *a, const char *b, size_t len)
{
        smb_ucs2_t cp = 0;
        size_t n = 0;

        while ((n < len) && *b && *(COPY_UCS2_CHAR(&cp,a)) == UCS2_CHAR(*b)) {
                a++;
                b++;
                n++;
        }
        return (len - n)?(*(COPY_UCS2_CHAR(&cp,a)) - UCS2_CHAR(*b)):0;
}

smb_ucs2_t *strpbrk_wa(const smb_ucs2_t *s, const char *p)
{
        smb_ucs2_t cp;

        while (*(COPY_UCS2_CHAR(&cp,s))) {
                int i;
                for (i=0; p[i] && cp != UCS2_CHAR(p[i]); i++) 
                        ;
                if (p[i]) {
                        return (smb_ucs2_t *)s;
                }
                s++;
        }
        return NULL;
}

smb_ucs2_t *strstr_wa(const smb_ucs2_t *s, const char *ins)
{
        smb_ucs2_t *r;
        size_t inslen;

        if (!s || !ins) { 
                return NULL;
        }

        inslen = strlen(ins);
        r = (smb_ucs2_t *)s;

        while ((r = strchr_w(r, UCS2_CHAR(*ins)))) {
                if (strncmp_wa(r, ins, inslen) == 0) 
                        return r;
                r++;
        }

        return NULL;
}

/*******************************************************************
 Returns the length in number of wide characters.
******************************************************************/

int unistrlen(uint16 *s)
{
        int len;

        if (!s) {
                return -1;
        }

        for (len=0; SVAL(s,0); s++,len++) {
                ;
        }

        return len;
}

/*******************************************************************
 Strcpy for unicode strings. Returns length (in num of wide chars).
 Not odd align safe.
********************************************************************/

int unistrcpy(uint16 *dst, uint16 *src)
{
        int num_wchars = 0;

        while (SVAL(src,0)) {
                *dst++ = *src++;
                num_wchars++;
        }
        *dst = 0;

        return num_wchars;
}

/**
 * Samba ucs2 type to UNISTR2 conversion
 *
 * @param ctx Talloc context to create the dst strcture (if null) and the 
 *            contents of the unicode string.
 * @param dst UNISTR2 destination. If equals null, then it's allocated.
 * @param src smb_ucs2_t source.
 * @param max_len maximum number of unicode characters to copy. If equals
 *        null, then null-termination of src is taken
 *
 * @return copied UNISTR2 destination
 **/

UNISTR2* ucs2_to_unistr2(TALLOC_CTX *ctx, UNISTR2* dst, smb_ucs2_t* src)
{
        size_t len;

        if (!src) {
                return NULL;
        }

        len = strlen_w(src);
        
        /* allocate UNISTR2 destination if not given */
        if (!dst) {
                dst = TALLOC_P(ctx, UNISTR2);
                if (!dst)
                        return NULL;
        }
        if (!dst->buffer) {
                dst->buffer = TALLOC_ARRAY(ctx, uint16, len + 1);
                if (!dst->buffer)
                        return NULL;
        }
        
        /* set UNISTR2 parameters */
        dst->uni_max_len = len + 1;
        dst->offset = 0;
        dst->uni_str_len = len;
        
        /* copy the actual unicode string */
        strncpy_w(dst->buffer, src, dst->uni_max_len);
        
        return dst;
}

/*************************************************************
 ascii only toupper - saves the need for smbd to be in C locale.
*************************************************************/

int toupper_ascii(int c)
{
        smb_ucs2_t uc = toupper_w(UCS2_CHAR(c));
        return UCS2_TO_CHAR(uc);
}

/*************************************************************
 ascii only tolower - saves the need for smbd to be in C locale.
*************************************************************/

int tolower_ascii(int c)
{
        smb_ucs2_t uc = tolower_w(UCS2_CHAR(c));
        return UCS2_TO_CHAR(uc);
}

/*************************************************************
 ascii only isupper - saves the need for smbd to be in C locale.
*************************************************************/

int isupper_ascii(int c)
{
        return isupper_w(UCS2_CHAR(c));
}

/*************************************************************
 ascii only islower - saves the need for smbd to be in C locale.
*************************************************************/

int islower_ascii(int c)
{
        return islower_w(UCS2_CHAR(c));
}