kc3-lang/libxml2/encoding.c

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• Hash : 361d845d
  Author :
  Date : 2000-04-03T19:48:13
  

  Work done on the plane, ready to release libxml2-2.0.0, Daniel
  

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• encoding.c

• /*
   * encoding.c : implements the encoding conversion functions needed for XML
   *
   * Related specs: 
   * rfc2044        (UTF-8 and UTF-16) F. Yergeau Alis Technologies
   * [ISO-10646]    UTF-8 and UTF-16 in Annexes
   * [ISO-8859-1]   ISO Latin-1 characters codes.
   * [UNICODE]      The Unicode Consortium, "The Unicode Standard --
   *                Worldwide Character Encoding -- Version 1.0", Addison-
   *                Wesley, Volume 1, 1991, Volume 2, 1992.  UTF-8 is
   *                described in Unicode Technical Report #4.
   * [US-ASCII]     Coded Character Set--7-bit American Standard Code for
   *                Information Interchange, ANSI X3.4-1986.
   *
   * Original code for IsoLatin1 and UTF-16 by "Martin J. Duerst" <duerst@w3.org>
   *
   * See Copyright for the status of this software.
   *
   * Daniel.Veillard@w3.org
   */
  
  #ifdef WIN32
  #include "win32config.h"
  #else
  #include "config.h"
  #endif
  
  #include <stdio.h>
  #include <string.h>
  
  #ifdef HAVE_CTYPE_H
  #include <ctype.h>
  #endif
  #ifdef HAVE_STDLIB_H
  #include <stdlib.h>
  #endif
  #include <libxml/encoding.h>
  #include <libxml/xmlmemory.h>
  
  xmlCharEncodingHandlerPtr xmlUTF16LEHandler = NULL;
  xmlCharEncodingHandlerPtr xmlUTF16BEHandler = NULL;
  
  /*
   * From rfc2044: encoding of the Unicode values on UTF-8:
   *
   * UCS-4 range (hex.)           UTF-8 octet sequence (binary)
   * 0000 0000-0000 007F   0xxxxxxx
   * 0000 0080-0000 07FF   110xxxxx 10xxxxxx
   * 0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx 
   *
   * I hope we won't use values > 0xFFFF anytime soon !
   */
  
  /**
   * xmlCheckUTF8: Check utf-8 string for legality.
   * @utf: Pointer to putative utf-8 encoded string.
   *
   * Checks @utf for being valid utf-8. @utf is assumed to be
   * null-terminated. This function is not super-strict, as it will
   * allow longer utf-8 sequences than necessary. Note that Java is
   * capable of producing these sequences if provoked. Also note, this
   * routine checks for the 4-byte maxiumum size, but does not check for
   * 0x10ffff maximum value.
   *
   * Return value: true if @utf is valid.
   **/
  int
  xmlCheckUTF8(const unsigned char *utf)
  {
      int ix;
      unsigned char c;
  
      for (ix = 0; (c = utf[ix]);) {
          if (c & 0x80) {
  	    if ((utf[ix + 1] & 0xc0) != 0x80)
  	        return(0);
  	    if ((c & 0xe0) == 0xe0) {
  	        if ((utf[ix + 2] & 0xc0) != 0x80)
  		    return(0);
  	        if ((c & 0xf0) == 0xf0) {
  		    if ((c & 0xf8) != 0xf0 || (utf[ix + 3] & 0xc0) != 0x80)
  		        return(0);
  		    ix += 4;
  		    /* 4-byte code */
  	        } else
  		  /* 3-byte code */
  		    ix += 3;
  	    } else
  	      /* 2-byte code */
  	        ix += 2;
  	} else
  	    /* 1-byte code */
  	    ix++;
        }
        return(1);
  }
  
  /**
   * isolat1ToUTF8:
   * @out:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @out
   * @in:  a pointer to an array of ISO Latin 1 chars
   * @inlen:  the length of @in
   *
   * Take a block of ISO Latin 1 chars in and try to convert it to an UTF-8
   * block of chars out.
   * Returns the number of byte written, or -1 by lack of space.
   */
  int
  isolat1ToUTF8(unsigned char* out, int outlen,
                const unsigned char* in, int *inlen) {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      const unsigned char* inend= in+*inlen;
      unsigned char c;
  
      while (in < inend) {
          c= *in++;
          if (c < 0x80) {
              if (out >= outend)  return(-1);
              *out++ = c;
          }
          else {
              if (out >= outend)  return(-1);
              *out++ = 0xC0 | (c >> 6);
              if (out >= outend)  return(-1);
              *out++ = 0x80 | (0x3F & c);
          }
      }
      return(out-outstart);
  }
  
  /**
   * UTF8Toisolat1:
   * @out:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @out
   * @in:  a pointer to an array of UTF-8 chars
   * @inlen:  the length of @in
   *
   * Take a block of UTF-8 chars in and try to convert it to an ISO Latin 1
   * block of chars out.
   * TODO: UTF8Toisolat1 need a fallback mechanism ...
   *
   * Returns the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding fails (for *in is not valid utf8 string or
   *     the result of transformation can't fit into the encoding we want)
   * The value of @inlen after return is the number of octets consumed
   *     as the return value is positive, else unpredictiable.
   */
  int
  UTF8Toisolat1(unsigned char* out, int outlen,
                const unsigned char* in, int *inlen) {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      const unsigned char* inend= in+*inlen;
      unsigned char c;
  
      while (in < inend) {
          c= *in++;
          if (c < 0x80) {
              if (out >= outend)  return(-1);
              *out++= c;
          }
  	else if (in == inend) {
              *inlen -= 1;
              break;
  	}
  	else if (((c & 0xFC) == 0xC0) && ((*in & 0xC0) == 0x80)) {
  	    /* a two byte utf-8 and can be encoding as isolate1 */
              *out++= ((c & 0x03) << 6) | (*in++ & 0x3F);
  	}
  	else
  	    return(-2);
  	/* TODO : some should be represent as "&#x____;" */
      }
      return(out-outstart);
  }
  
  /**
   * UTF16LEToUTF8:
   * @out:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @out
   * @inb:  a pointer to an array of UTF-16LE passwd as a byte array
   * @inlenb:  the length of @in in UTF-16LE chars
   *
   * Take a block of UTF-16LE ushorts in and try to convert it to an UTF-8
   * block of chars out. This function assume the endian properity
   * is the same between the native type of this machine and the
   * inputed one.
   *
   * Returns the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding fails (for *in is not valid utf16 string)
   *     The value of *inlen after return is the number of octets consumed
   *     as the return value is positive, else unpredictiable.
   */
  int
  UTF16LEToUTF8(unsigned char* out, int outlen,
              const unsigned char* inb, int *inlenb)
  {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      unsigned short* in = (unsigned short*) inb;
      unsigned short* inend;
      unsigned int c, d, inlen;
      unsigned char *tmp;
      int bits;
  
      if ((*inlenb % 2) == 1)
          (*inlenb)--;
      inlen = *inlenb / 2;
      inend= in + inlen;
      while (in < inend) {
  #ifdef BIG_ENDIAN
  	tmp = (unsigned char *) in;
  	c = *tmp++;
  	c = c | (((unsigned int)*tmp) << 8);
  	in++;
  #else /* BIG_ENDIAN */
          c= *in++;
  #endif /* BIG_ENDIAN */
          if ((c & 0xFC00) == 0xD800) {    /* surrogates */
              if (in >= inend) {           /* (in > inend) shouldn't happens */
                  (*inlenb) -= 2;
                  break;
              }
  #ifdef BIG_ENDIAN
              tmp = (unsigned char *) in;
              d = *tmp++;
  	    d = d | (((unsigned int)*tmp) << 8);
  	    in++;
  #else /* BIG_ENDIAN */
              d = *in++;
  #endif /* BIG_ENDIAN */
              if ((d & 0xFC00) == 0xDC00) {
                  c &= 0x03FF;
                  c <<= 10;
                  c |= d & 0x03FF;
                  c += 0x10000;
              }
              else
  	        return(-2);
          }
  
  	/* assertion: c is a single UTF-4 value */
          if (out >= outend)
  	    return(-1);
          if      (c <    0x80) {  *out++=  c;                bits= -6; }
          else if (c <   0x800) {  *out++= ((c >>  6) & 0x1F) | 0xC0;  bits=  0; }
          else if (c < 0x10000) {  *out++= ((c >> 12) & 0x0F) | 0xE0;  bits=  6; }
          else                  {  *out++= ((c >> 18) & 0x07) | 0xF0;  bits= 12; }
   
          for ( ; bits >= 0; bits-= 6) {
              if (out >= outend)
  	        return(-1);
              *out++= ((c >> bits) & 0x3F) | 0x80;
          }
      }
      return(out-outstart);
  }
  
  /**
   * UTF8ToUTF16LE:
   * @outb:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @outb
   * @in:  a pointer to an array of UTF-8 chars
   * @inlen:  the length of @in
   *
   * Take a block of UTF-8 chars in and try to convert it to an UTF-16LE
   * block of chars out.
   * TODO: UTF8ToUTF16LE need a fallback mechanism ...
   *
   * Returns the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding failed. 
   */
  int
  UTF8ToUTF16LE(unsigned char* outb, int outlen,
              const unsigned char* in, int *inlen)
  {
      unsigned short* out = (unsigned short*) outb;
      unsigned short* outstart= out;
      unsigned short* outend;
      const unsigned char* inend= in+*inlen;
      unsigned int c, d, trailing;
  #ifdef BIG_ENDIAN
      unsigned char *tmp;
      unsigned short tmp1, tmp2;
  #endif /* BIG_ENDIAN */
  
      outlen /= 2; /* convert in short length */
      outend = out + outlen;
      while (in < inend) {
        d= *in++;
        if      (d < 0x80)  { c= d; trailing= 0; }
        else if (d < 0xC0)
            return(-2);    /* trailing byte in leading position */
        else if (d < 0xE0)  { c= d & 0x1F; trailing= 1; }
        else if (d < 0xF0)  { c= d & 0x0F; trailing= 2; }
        else if (d < 0xF8)  { c= d & 0x07; trailing= 3; }
        else
            return(-2);    /* no chance for this in UTF-16 */
  
        if (inend - in < trailing) {
            *inlen -= (inend - in);
            break;
        } 
  
        for ( ; trailing; trailing--) {
            if ((in >= inend) || (((d= *in++) & 0xC0) != 0x80))
  	      return(-1);
            c <<= 6;
            c |= d & 0x3F;
        }
  
        /* assertion: c is a single UTF-4 value */
          if (c < 0x10000) {
              if (out >= outend)
  	        return(-1);
  #ifdef BIG_ENDIAN
              tmp = (unsigned char *) out;
              *tmp = c ;
              *(tmp + 1) = c >> 8 ;
              out++;
  #else /* BIG_ENDIAN */
              *out++ = c;
  #endif /* BIG_ENDIAN */
          }
          else if (c < 0x110000) {
              if (out+1 >= outend)
  	        return(-1);
              c -= 0x10000;
  #ifdef BIG_ENDIAN
              tmp1 = 0xD800 | (c >> 10);
              tmp = (unsigned char *) out;
              *tmp = tmp1;
              *(tmp + 1) = tmp1 >> 8;
              out++;
  
              tmp2 = 0xDC00 | (c & 0x03FF);
              tmp = (unsigned char *) out;
              *tmp  = tmp2;
              *(tmp + 1) = tmp2 >> 8;
              out++;
  #else /* BIG_ENDIAN */
              *out++ = 0xD800 | (c >> 10);
              *out++ = 0xDC00 | (c & 0x03FF);
  #endif /* BIG_ENDIAN */
          }
          else
  	    return(-1);
      }
      return(out-outstart);
  }
  
  /**
   * UTF16BEToUTF8:
   * @out:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @out
   * @inb:  a pointer to an array of UTF-16 passwd as a byte array
   * @inlenb:  the length of @in in UTF-16 chars
   *
   * Take a block of UTF-16 ushorts in and try to convert it to an UTF-8
   * block of chars out. This function assume the endian properity
   * is the same between the native type of this machine and the
   * inputed one.
   *
   * Returns the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding fails (for *in is not valid utf16 string)
   * The value of *inlen after return is the number of octets consumed
   *     as the return value is positive, else unpredictiable.
   */
  int
  UTF16BEToUTF8(unsigned char* out, int outlen,
              const unsigned char* inb, int *inlenb)
  {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      unsigned short* in = (unsigned short*) inb;
      unsigned short* inend;
      unsigned int c, d, inlen;
  #ifdef BIG_ENDIAN
  #else /* BIG_ENDIAN */
      unsigned char *tmp;
  #endif /* BIG_ENDIAN */    
      int bits;
  
      if ((*inlenb % 2) == 1)
          (*inlenb)--;
      inlen = *inlenb / 2;
      inend= in + inlen;
      while (in < inend) {
  #ifdef BIG_ENDIAN    
          c= *in++;
  #else
          tmp = (unsigned char *) in;
  	c = *tmp++;
  	c = c << 8;
  	c = c | (unsigned int) *tmp;
  	in++;
  #endif	
          if ((c & 0xFC00) == 0xD800) {    /* surrogates */
  	    if (in >= inend) {           /* (in > inend) shouldn't happens */
  	        (*inlenb) -= 2;
  		break;
  	    }
  
  #ifdef BIG_ENDIAN
              d= *in++;
  #else
              tmp = (unsigned char *) in;
  	    d = *tmp++;
  	    d = d << 8;
  	    d = d | (unsigned int) *tmp;
  	    in++;
  #endif	    
              if ((d & 0xFC00) == 0xDC00) {
                  c &= 0x03FF;
                  c <<= 10;
                  c |= d & 0x03FF;
                  c += 0x10000;
              }
              else 
  	        return(-2);
          }
  
  	/* assertion: c is a single UTF-4 value */
          if (out >= outend) 
  	    return(-1);
          if      (c <    0x80) {  *out++=  c;                bits= -6; }
          else if (c <   0x800) {  *out++= ((c >>  6) & 0x1F) | 0xC0;  bits=  0; }
          else if (c < 0x10000) {  *out++= ((c >> 12) & 0x0F) | 0xE0;  bits=  6; }
          else                  {  *out++= ((c >> 18) & 0x07) | 0xF0;  bits= 12; }
   
          for ( ; bits >= 0; bits-= 6) {
              if (out >= outend) 
  	        return(-1);
              *out++= ((c >> bits) & 0x3F) | 0x80;
          }
      }
      return(out-outstart);
  }
  
  /**
   * UTF8ToUTF16BE:
   * @outb:  a pointer to an array of bytes to store the result
   * @outlen:  the length of @outb
   * @in:  a pointer to an array of UTF-8 chars
   * @inlen:  the length of @in
   *
   * Take a block of UTF-8 chars in and try to convert it to an UTF-16BE
   * block of chars out.
   * TODO: UTF8ToUTF16BE need a fallback mechanism ...
   *
   * Returns the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding failed. 
   */
  int
  UTF8ToUTF16BE(unsigned char* outb, int outlen,
              const unsigned char* in, int *inlen)
  {
      unsigned short* out = (unsigned short*) outb;
      unsigned short* outstart= out;
      unsigned short* outend;
      const unsigned char* inend= in+*inlen;
      unsigned int c, d, trailing;
  #ifdef BIG_ENDIAN
  #else
      unsigned char *tmp;
      unsigned short tmp1, tmp2;
  #endif /* BIG_ENDIAN */    
  
      outlen /= 2; /* convert in short length */
      outend = out + outlen;
      while (in < inend) {
        d= *in++;
        if      (d < 0x80)  { c= d; trailing= 0; }
        else if (d < 0xC0)
            return(-2);    /* trailing byte in leading position */
        else if (d < 0xE0)  { c= d & 0x1F; trailing= 1; }
        else if (d < 0xF0)  { c= d & 0x0F; trailing= 2; }
        else if (d < 0xF8)  { c= d & 0x07; trailing= 3; }
        else
            return(-2);    /* no chance for this in UTF-16 */
  
        if (inend - in < trailing) {
            *inlen -= (inend - in);
            break;
        } 
  
        for ( ; trailing; trailing--) {
            if ((in >= inend) || (((d= *in++) & 0xC0) != 0x80))  return(-1);
            c <<= 6;
            c |= d & 0x3F;
        }
  
        /* assertion: c is a single UTF-4 value */
          if (c < 0x10000) {
              if (out >= outend)  return(-1);
  #ifdef BIG_ENDIAN
              *out++ = c;
  #else
              tmp = (unsigned char *) out;
              *tmp = c >> 8;
              *(tmp + 1) = c;
              out++;
  #endif /* BIG_ENDIAN */
          }
          else if (c < 0x110000) {
              if (out+1 >= outend)  return(-1);
              c -= 0x10000;
  #ifdef BIG_ENDIAN
              *out++ = 0xD800 | (c >> 10);
              *out++ = 0xDC00 | (c & 0x03FF);
  #else
              tmp1 = 0xD800 | (c >> 10);
              tmp = (unsigned char *) out;
              *tmp = tmp1 >> 8;
              *(tmp + 1) = tmp1;
              out++;
  
              tmp2 = 0xDC00 | (c & 0x03FF);
              tmp = (unsigned char *) out;
              *tmp = tmp2 >> 8;
              *(tmp + 1) = tmp2;
              out++;
  #endif
          }
          else  return(-1);
      }
      return(out-outstart);
  }
  
  /**
   * xmlDetectCharEncoding:
   * @in:  a pointer to the first bytes of the XML entity, must be at least
   *       4 bytes long.
   * @len:  pointer to the length of the buffer
   *
   * Guess the encoding of the entity using the first bytes of the entity content
   * accordingly of the non-normative appendix F of the XML-1.0 recommendation.
   * 
   * Returns one of the XML_CHAR_ENCODING_... values.
   */
  xmlCharEncoding
  xmlDetectCharEncoding(const unsigned char* in, int len)
  {
      if (len >= 4) {
  	if ((in[0] == 0x00) && (in[1] == 0x00) &&
  	    (in[2] == 0x00) && (in[3] == 0x3C))
  	    return(XML_CHAR_ENCODING_UCS4BE);
  	if ((in[0] == 0x3C) && (in[1] == 0x00) &&
  	    (in[2] == 0x00) && (in[3] == 0x00))
  	    return(XML_CHAR_ENCODING_UCS4LE);
  	if ((in[0] == 0x00) && (in[1] == 0x00) &&
  	    (in[2] == 0x3C) && (in[3] == 0x00))
  	    return(XML_CHAR_ENCODING_UCS4_2143);
  	if ((in[0] == 0x00) && (in[1] == 0x3C) &&
  	    (in[2] == 0x00) && (in[3] == 0x00))
  	    return(XML_CHAR_ENCODING_UCS4_3412);
  	if ((in[0] == 0x4C) && (in[1] == 0x6F) &&
  	    (in[2] == 0xA7) && (in[3] == 0x94))
  	    return(XML_CHAR_ENCODING_EBCDIC);
  	if ((in[0] == 0x3C) && (in[1] == 0x3F) &&
  	    (in[2] == 0x78) && (in[3] == 0x6D))
  	    return(XML_CHAR_ENCODING_UTF8);
      }
      if (len >= 2) {
  	if ((in[0] == 0xFE) && (in[1] == 0xFF))
  	    return(XML_CHAR_ENCODING_UTF16BE);
  	if ((in[0] == 0xFF) && (in[1] == 0xFE))
  	    return(XML_CHAR_ENCODING_UTF16LE);
      }
      return(XML_CHAR_ENCODING_NONE);
  }
  
  /**
   * xmlParseCharEncoding:
   * @name:  the encoding name as parsed, in UTF-8 format (ASCII actually)
   *
   * Conpare the string to the known encoding schemes already known. Note
   * that the comparison is case insensitive accordingly to the section
   * [XML] 4.3.3 Character Encoding in Entities.
   * 
   * Returns one of the XML_CHAR_ENCODING_... values or XML_CHAR_ENCODING_NONE
   * if not recognized.
   */
  xmlCharEncoding
  xmlParseCharEncoding(const char* name)
  {
      char upper[500];
      int i;
  
      for (i = 0;i < 499;i++) {
          upper[i] = toupper(name[i]);
  	if (upper[i] == 0) break;
      }
      upper[i] = 0;
  
      if (!strcmp(upper, "")) return(XML_CHAR_ENCODING_NONE);
      if (!strcmp(upper, "UTF-8")) return(XML_CHAR_ENCODING_UTF8);
      if (!strcmp(upper, "UTF8")) return(XML_CHAR_ENCODING_UTF8);
  
      /*
       * NOTE: if we were able to parse this, the endianness of UTF16 is
       *       already found and in use
       */
      if (!strcmp(upper, "UTF-16")) return(XML_CHAR_ENCODING_UTF16LE);
      if (!strcmp(upper, "UTF16")) return(XML_CHAR_ENCODING_UTF16LE);
      
      if (!strcmp(upper, "ISO-10646-UCS-2")) return(XML_CHAR_ENCODING_UCS2);
      if (!strcmp(upper, "UCS-2")) return(XML_CHAR_ENCODING_UCS2);
      if (!strcmp(upper, "UCS2")) return(XML_CHAR_ENCODING_UCS2);
  
      /*
       * NOTE: if we were able to parse this, the endianness of UCS4 is
       *       already found and in use
       */
      if (!strcmp(upper, "ISO-10646-UCS-4")) return(XML_CHAR_ENCODING_UCS4LE);
      if (!strcmp(upper, "UCS-4")) return(XML_CHAR_ENCODING_UCS4LE);
      if (!strcmp(upper, "UCS4")) return(XML_CHAR_ENCODING_UCS4LE);
  
      
      if (!strcmp(upper,  "ISO-8859-1")) return(XML_CHAR_ENCODING_8859_1);
      if (!strcmp(upper,  "ISO-LATIN-1")) return(XML_CHAR_ENCODING_8859_1);
      if (!strcmp(upper,  "ISO LATIN 1")) return(XML_CHAR_ENCODING_8859_1);
  
      if (!strcmp(upper,  "ISO-8859-2")) return(XML_CHAR_ENCODING_8859_2);
      if (!strcmp(upper,  "ISO-LATIN-2")) return(XML_CHAR_ENCODING_8859_2);
      if (!strcmp(upper,  "ISO LATIN 2")) return(XML_CHAR_ENCODING_8859_2);
  
      if (!strcmp(upper,  "ISO-8859-3")) return(XML_CHAR_ENCODING_8859_3);
      if (!strcmp(upper,  "ISO-8859-4")) return(XML_CHAR_ENCODING_8859_4);
      if (!strcmp(upper,  "ISO-8859-5")) return(XML_CHAR_ENCODING_8859_5);
      if (!strcmp(upper,  "ISO-8859-6")) return(XML_CHAR_ENCODING_8859_6);
      if (!strcmp(upper,  "ISO-8859-7")) return(XML_CHAR_ENCODING_8859_7);
      if (!strcmp(upper,  "ISO-8859-8")) return(XML_CHAR_ENCODING_8859_8);
      if (!strcmp(upper,  "ISO-8859-9")) return(XML_CHAR_ENCODING_8859_9);
  
      if (!strcmp(upper, "ISO-2022-JP")) return(XML_CHAR_ENCODING_2022_JP);
      if (!strcmp(upper, "Shift_JIS")) return(XML_CHAR_ENCODING_SHIFT_JIS);
      if (!strcmp(upper, "EUC-JP")) return(XML_CHAR_ENCODING_EUC_JP);
      return(XML_CHAR_ENCODING_ERROR);
  }
  
  /****************************************************************
   *								*
   *		Char encoding handlers				*
   *								*
   ****************************************************************/
  
  /* the size should be growable, but it's not a big deal ... */
  #define MAX_ENCODING_HANDLERS 50
  static xmlCharEncodingHandlerPtr *handlers = NULL;
  static int nbCharEncodingHandler = 0;
  
  /*
   * The default is UTF-8 for XML, that's also the default used for the
   * parser internals, so the default encoding handler is NULL
   */
  
  static xmlCharEncodingHandlerPtr xmlDefaultCharEncodingHandler = NULL;
  
  /**
   * xmlNewCharEncodingHandler:
   * @name:  the encoding name, in UTF-8 format (ASCII actually)
   * @input:  the xmlCharEncodingInputFunc to read that encoding
   * @output:  the xmlCharEncodingOutputFunc to write that encoding
   *
   * Create and registers an xmlCharEncodingHandler.
   * Returns the xmlCharEncodingHandlerPtr created (or NULL in case of error).
   */
  xmlCharEncodingHandlerPtr
  xmlNewCharEncodingHandler(const char *name, 
                            xmlCharEncodingInputFunc input,
                            xmlCharEncodingOutputFunc output) {
      xmlCharEncodingHandlerPtr handler;
      char upper[500];
      int i;
      char *up = 0;
  
      /*
       * Keep only the uppercase version of the encoding.
       */
      if (name == NULL) {
          fprintf(stderr, "xmlNewCharEncodingHandler : no name !\n");
  	return(NULL);
      }
      for (i = 0;i < 499;i++) {
          upper[i] = toupper(name[i]);
  	if (upper[i] == 0) break;
      }
      upper[i] = 0;
      up = xmlMemStrdup(upper);
      if (up == NULL) {
          fprintf(stderr, "xmlNewCharEncodingHandler : out of memory !\n");
  	return(NULL);
      }
  
      /*
       * allocate and fill-up an handler block.
       */
      handler = (xmlCharEncodingHandlerPtr)
                xmlMalloc(sizeof(xmlCharEncodingHandler));
      if (handler == NULL) {
          fprintf(stderr, "xmlNewCharEncodingHandler : out of memory !\n");
  	return(NULL);
      }
      handler->input = input;
      handler->output = output;
      handler->name = up;
  
      /*
       * registers and returns the handler.
       */
      xmlRegisterCharEncodingHandler(handler);
      return(handler);
  }
  
  /**
   * xmlInitCharEncodingHandlers:
   *
   * Initialize the char encoding support, it registers the default
   * encoding supported.
   * NOTE: while public, this function usually doesn't need to be called
   *       in normal processing.
   */
  void
  xmlInitCharEncodingHandlers(void) {
      if (handlers != NULL) return;
  
      handlers = (xmlCharEncodingHandlerPtr *)
          xmlMalloc(MAX_ENCODING_HANDLERS * sizeof(xmlCharEncodingHandlerPtr));
  
      if (handlers == NULL) {
          fprintf(stderr, "xmlInitCharEncodingHandlers : out of memory !\n");
  	return;
      }
      xmlNewCharEncodingHandler("UTF-8", NULL, NULL);
      xmlUTF16LEHandler = 
            xmlNewCharEncodingHandler("UTF-16LE", UTF16LEToUTF8, UTF8ToUTF16LE);
      xmlUTF16BEHandler = 
            xmlNewCharEncodingHandler("UTF-16BE", UTF16BEToUTF8, UTF8ToUTF16BE);
      xmlNewCharEncodingHandler("ISO-8859-1", isolat1ToUTF8, UTF8Toisolat1);
  }
  
  /**
   * xmlCleanupCharEncodingHandlers:
   *
   * Cleanup the memory allocated for the char encoding support, it
   * unregisters all the encoding handlers.
   */
  void
  xmlCleanupCharEncodingHandlers(void) {
      if (handlers == NULL) return;
  
      for (;nbCharEncodingHandler > 0;) {
          nbCharEncodingHandler--;
  	if (handlers[nbCharEncodingHandler] != NULL) {
  	    xmlFree(handlers[nbCharEncodingHandler]->name);
  	    xmlFree(handlers[nbCharEncodingHandler]);
  	}
      }
      xmlFree(handlers);
      handlers = NULL;
      nbCharEncodingHandler = 0;
      xmlDefaultCharEncodingHandler = NULL;
  }
  
  /**
   * xmlRegisterCharEncodingHandler:
   * @handler:  the xmlCharEncodingHandlerPtr handler block
   *
   * Register the char encoding handler, surprizing, isn't it ?
   */
  void
  xmlRegisterCharEncodingHandler(xmlCharEncodingHandlerPtr handler) {
      if (handlers == NULL) xmlInitCharEncodingHandlers();
      if (handler == NULL) {
          fprintf(stderr, "xmlRegisterCharEncodingHandler: NULL handler !\n");
  	return;
      }
  
      if (nbCharEncodingHandler >= MAX_ENCODING_HANDLERS) {
          fprintf(stderr, 
  	"xmlRegisterCharEncodingHandler: Too many handler registered\n");
          fprintf(stderr, "\tincrease MAX_ENCODING_HANDLERS : %s\n", __FILE__);
  	return;
      }
      handlers[nbCharEncodingHandler++] = handler;
  }
  
  /**
   * xmlGetCharEncodingHandler:
   * @enc:  an xmlCharEncoding value.
   *
   * Search in the registrered set the handler able to read/write that encoding.
   *
   * Returns the handler or NULL if not found
   */
  xmlCharEncodingHandlerPtr
  xmlGetCharEncodingHandler(xmlCharEncoding enc) {
      if (handlers == NULL) xmlInitCharEncodingHandlers();
      switch (enc) {
          case XML_CHAR_ENCODING_ERROR:
  	    return(NULL);
          case XML_CHAR_ENCODING_NONE:
  	    return(NULL);
          case XML_CHAR_ENCODING_UTF8:
  	    return(NULL);
          case XML_CHAR_ENCODING_UTF16LE:
  	    return(xmlUTF16LEHandler);
          case XML_CHAR_ENCODING_UTF16BE:
  	    return(xmlUTF16BEHandler);
          case XML_CHAR_ENCODING_EBCDIC:
  	    return(NULL);
          case XML_CHAR_ENCODING_UCS4LE:
  	    return(NULL);
          case XML_CHAR_ENCODING_UCS4BE:
  	    return(NULL);
          case XML_CHAR_ENCODING_UCS4_2143:
  	    return(NULL);
          case XML_CHAR_ENCODING_UCS4_3412:
  	    return(NULL);
          case XML_CHAR_ENCODING_UCS2:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_1:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_2:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_3:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_4:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_5:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_6:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_7:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_8:
  	    return(NULL);
          case XML_CHAR_ENCODING_8859_9:
  	    return(NULL);
          case XML_CHAR_ENCODING_2022_JP:
          case XML_CHAR_ENCODING_SHIFT_JIS:
          case XML_CHAR_ENCODING_EUC_JP:
  	    return(NULL);
      }
      return(NULL);
  }
  
  /**
   * xmlGetCharEncodingHandler:
   * @enc:  a string describing the char encoding.
   *
   * Search in the registrered set the handler able to read/write that encoding.
   *
   * Returns the handler or NULL if not found
   */
  xmlCharEncodingHandlerPtr
  xmlFindCharEncodingHandler(const char *name) {
      char upper[500];
      int i;
  
      if (handlers == NULL) xmlInitCharEncodingHandlers();
      if (name == NULL) return(xmlDefaultCharEncodingHandler);
      if (name[0] == 0) return(xmlDefaultCharEncodingHandler);
  
      for (i = 0;i < 499;i++) {
          upper[i] = toupper(name[i]);
  	if (upper[i] == 0) break;
      }
      upper[i] = 0;
  
      for (i = 0;i < nbCharEncodingHandler; i++)
          if (!strcmp(name, handlers[i]->name))
  	    return(handlers[i]);
  
      return(NULL);
  }
  
  

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