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libiconv 1.16

    1: /*
    2:  * Copyright (C) 1999-2001, 2008, 2016 Free Software Foundation, Inc.
    3:  * This file is part of the GNU LIBICONV Library.
    4:  *
    5:  * The GNU LIBICONV Library is free software; you can redistribute it
    6:  * and/or modify it under the terms of the GNU Library General Public
    7:  * License as published by the Free Software Foundation; either version 2
    8:  * of the License, or (at your option) any later version.
    9:  *
   10:  * The GNU LIBICONV Library is distributed in the hope that it will be
   11:  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13:  * Library General Public License for more details.
   14:  *
   15:  * You should have received a copy of the GNU Library General Public
   16:  * License along with the GNU LIBICONV Library; see the file COPYING.LIB.
   17:  * If not, see <https://www.gnu.org/licenses/>.
   18:  */
   19: 
   20: /*
   21:  * UTF-16
   22:  */
   23: 
   24: /* Specification: RFC 2781 */
   25: 
   26: /* Here we accept FFFE/FEFF marks as endianness indicators everywhere
   27:    in the stream, not just at the beginning. (This is contrary to what
   28:    RFC 2781 section 3.2 specifies, but it allows concatenation of byte
   29:    sequences to work flawlessly, while disagreeing with the RFC behaviour
   30:    only for strings containing U+FEFF characters, which is quite rare.)
   31:    The default is big-endian. */
   32: /* The state is 0 if big-endian, 1 if little-endian. */
   33: static int
   34: utf16_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, size_t n)
   35: {
   36:   state_t state = conv->istate;
   37:   int count = 0;
   38:   for (; n >= 2 && count <= RET_COUNT_MAX && count <= INT_MAX-2;) {
   39:     ucs4_t wc = (state ? s[0] + (s[1] << 8) : (s[0] << 8) + s[1]);
   40:     if (wc == 0xfeff) {
   41:     } else if (wc == 0xfffe) {
   42:       state ^= 1;
   43:     } else if (wc >= 0xd800 && wc < 0xdc00) {
   44:       if (n >= 4) {
   45:         ucs4_t wc2 = (state ? s[2] + (s[3] << 8) : (s[2] << 8) + s[3]);
   46:         if (!(wc2 >= 0xdc00 && wc2 < 0xe000))
   47:           goto ilseq;
   48:         *pwc = 0x10000 + ((wc - 0xd800) << 10) + (wc2 - 0xdc00);
   49:         conv->istate = state;
   50:         return count+4;
   51:       } else
   52:         break;
   53:     } else if (wc >= 0xdc00 && wc < 0xe000) {
   54:       goto ilseq;
   55:     } else {
   56:       *pwc = wc;
   57:       conv->istate = state;
   58:       return count+2;
   59:     }
   60:     s += 2; n -= 2; count += 2;
   61:   }
   62:   conv->istate = state;
   63:   return RET_TOOFEW(count);
   64: 
   65: ilseq:
   66:   conv->istate = state;
   67:   return RET_SHIFT_ILSEQ(count);
   68: }
   69: 
   70: /* We output UTF-16 in big-endian order, with byte-order mark.
   71:    See RFC 2781 section 3.3 for a rationale: Some document formats
   72:    mandate a BOM; the file concatenation issue is not so severe as
   73:    long as the above utf16_mbtowc function is used. */
   74: /* The state is 0 at the beginning, 1 after the BOM has been written. */
   75: static int
   76: utf16_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, size_t n)
   77: {
   78:   if (wc != 0xfffe && !(wc >= 0xd800 && wc < 0xe000)) {
   79:     int count = 0;
   80:     if (!conv->ostate) {
   81:       if (n >= 2) {
   82:         r[0] = 0xFE;
   83:         r[1] = 0xFF;
   84:         r += 2; n -= 2; count += 2;
   85:       } else
   86:         return RET_TOOSMALL;
   87:     }
   88:     if (wc < 0x10000) {
   89:       if (n >= 2) {
   90:         r[0] = (unsigned char) (wc >> 8);
   91:         r[1] = (unsigned char) wc;
   92:         conv->ostate = 1;
   93:         return count+2;
   94:       } else
   95:         return RET_TOOSMALL;
   96:     }
   97:     else if (wc < 0x110000) {
   98:       if (n >= 4) {
   99:         ucs4_t wc1 = 0xd800 + ((wc - 0x10000) >> 10);
  100:         ucs4_t wc2 = 0xdc00 + ((wc - 0x10000) & 0x3ff);
  101:         r[0] = (unsigned char) (wc1 >> 8);
  102:         r[1] = (unsigned char) wc1;
  103:         r[2] = (unsigned char) (wc2 >> 8);
  104:         r[3] = (unsigned char) wc2;
  105:         conv->ostate = 1;
  106:         return count+4;
  107:       } else
  108:         return RET_TOOSMALL;
  109:     }
  110:   }
  111:   return RET_ILUNI;
  112: }