FreeBSD/Linux Kernel Cross Reference
sys/fs/unicode.h

     /* $NetBSD: unicode.h,v 1.2 2004/12/27 18:14:36 jdolecek Exp $ */
     
     /*-
      * Copyright (c) 2001, 2004 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *        This product includes software developed by the NetBSD
     *        Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Routines for handling Unicode encoded in UTF-8 form, code derived from
     * src/lib/libc/locale/utf2.c.
     */
    
    /*
     * Read one UTF8-encoded character off the string, shift the string pointer
     * and return the character.
     */
    static u_int16_t
    wget_utf8(const char **str, size_t *sz)
    {
            int c;
            u_int16_t rune = 0;
            const char *s = *str;
            static const int _utf_count[16] = {
                    1, 1, 1, 1, 1, 1, 1, 1,
                    0, 0, 0, 0, 2, 2, 3, 0,
            };
    
            /* must be called with at least one byte remaining */
            KASSERT(*sz > 0);
    
            c = _utf_count[(s[0] & 0xf0) >> 4];
            if (c == 0 || c > *sz) {
        decoding_error:
                    /*
                     * The first character is in range 128-255 and doesn't
                     * mark valid a valid UTF-8 sequence. There is not much
                     * we can do with this, so handle by returning
                     * the first character as if it would be a correctly
                     * encoded ISO-8859-1 character.
                     */
                    c = 1;
            }
    
            switch (c) {
            case 1:
                    rune = s[0] & 0xff;
                    break;
            case 2:
                    if ((s[1] & 0xc0) != 0x80)
                            goto decoding_error;
                    rune = ((s[0] & 0x1F) << 6) | (s[1] & 0x3F);
                    break;
            case 3:
                    if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80)
                            goto decoding_error;
                    rune = ((s[0] & 0x1F) << 12) | ((s[1] & 0x3F) << 6)
                        | (s[2] & 0x3F);
                    break;
            }
    
            *str += c;
            *sz -= c;
            return rune;
    }
    
    /*
     * Encode wide character and write it to the string. 'n' specifies
     * how much buffer space remains in 's'. Returns number of bytes written
     * to the target string 's'.
     */
    static int
   wput_utf8(char *s, size_t n, u_int16_t wc)
   {
           if (wc & 0xf800) {
                   if (n < 3) {
                           /* bound check failure */
                           return 0;
                   }
   
                   s[0] = 0xE0 | ((wc >> 12) & 0x0F);
                   s[1] = 0x80 | ((wc >> 6) & 0x3F);
                   s[2] = 0x80 | ((wc) & 0x3F);
                   return 3;
           } else if (wc & 0x0780) {
                   if (n < 2) {
                           /* bound check failure */
                           return 0;
                   }
   
                   s[0] = 0xC0 | ((wc >> 6) & 0x1F);
                   s[1] = 0x80 | ((wc) & 0x3F);
                   return 2;
           } else {
                   if (n < 1) {
                           /* bound check failure */
                           return 0;
                   }
   
                   s[0] = wc;
                   return 1;
           }
   }

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