pd.if.org Git - pdclib/blob - opt/basecodecs/_PDCLIB_utf8.c

   1 /* UTF-8 codec
   2
   3    This file is part of the Public Domain C Library (PDCLib).
   4    Permission is granted to use, modify, and / or redistribute at will.
   5 */
   6
   7 #ifndef REGTEST
   8 #include <stdbool.h>
   9 #include <stdint.h>
  10 #include <uchar.h>
  11 #include <assert.h>
  12 #include "_PDCLIB_encoding.h"
  13
  14 /* Use of the mbstate:
  15  *
  16  * _StUC[0] is the current decoding state
  17  * _St32[1] is the character accumulated so far
  18  */
  19
  20 static bool utf8_mbsinit( const mbstate_t *p_s )
  21 { return p_s->_StUC[0] == 0; }
  22
  23 enum {
  24     DecStart = 0,
  25
  26     Dec2B2,
  27
  28     Dec3B2,
  29     Dec3B3,
  30
  31     Dec4B2,
  32     Dec4B3,
  33     Dec4B4
  34 };
  35
  36 #define state (p_s->_StUC[0])
  37 #define accum (p_s->_St32[1])
  38
  39 #define START_CONVERSION \
  40     bool          result = true;           \
  41
  42 #define END_CONVERSION      \
  43 end_conversion:             \
  44     return result
  45
  46 #define FINISH(_r) do {     \
  47     result = (_r);          \
  48     goto end_conversion;    \
  49 } while(0)
  50
  51 #define OUT32(_c)  do {             \
  52     if(p_outbuf)                    \
  53         (*((*p_outbuf)++)) = (_c);  \
  54     (*p_outsz)--;                   \
  55     _PDCLIB_UNDEFINED(accum);       \
  56     state = DecStart;               \
  57 } while(0)
  58
  59 #define CHECK_CONTINUATION \
  60     do { if((c & 0xC0) != 0x80) return false; } while(0)
  61
  62 static bool utf8toc32(
  63     char32_t       *restrict *restrict   p_outbuf,
  64     size_t                   *restrict   p_outsz,
  65     const char     *restrict *restrict   p_inbuf,
  66     size_t                   *restrict   p_insz,
  67     mbstate_t                *restrict   p_s
  68 )
  69 {
  70     START_CONVERSION
  71     while(*p_outsz && *p_insz) {
  72         unsigned char c = **p_inbuf;
  73         char32_t      c32;
  74         switch(state) {
  75         case DecStart:
  76             // 1 byte
  77             if(c <= 0x7F) {
  78                 OUT32(c);
  79             } else if(c <= 0xDF) {
  80                 accum = (c & 0x1F) << 6;
  81                 state = Dec2B2;
  82             } else if(c <= 0xEF) {
  83                 accum = (c & 0x0F) << 12;
  84                 state = Dec3B2;
  85             } else if(c <= 0xF4) {
  86                 accum = (c & 0x07) << 18;
  87                 state = Dec4B2;
  88             } else {
  89                 // 5+byte sequence illegal
  90                 FINISH(false);
  91             }
  92             break;
  93
  94         case Dec2B2:
  95             CHECK_CONTINUATION;
  96
  97             c32 = accum | (c & 0x3F);
  98
  99             // Overlong sequence (e.g. NUL injection)
 100             if(c32 <= 0x7F)
 101                 FINISH(false);
 102
 103             OUT32(c32);
 104             break;
 105
 106         case Dec3B2:
 107             CHECK_CONTINUATION;
 108             accum |= (c & 0x3F) << 6;
 109             state = Dec3B3;
 110             break;
 111
 112         case Dec3B3:
 113             CHECK_CONTINUATION;
 114
 115             c32 = accum | (c & 0x3F);
 116
 117             // Overlong
 118             if(c32 <= 0x07FF)
 119                 FINISH(false);
 120
 121             // Surrogate
 122             if(c32 >= 0xD800 && c32 <= 0xDFFF)
 123                 FINISH(false);
 124
 125             OUT32(c32);
 126             break;
 127
 128         case Dec4B2:
 129             CHECK_CONTINUATION;
 130             accum |= (c & 0x3F) << 12;
 131             state = Dec4B3;
 132             break;
 133
 134         case Dec4B3:
 135             CHECK_CONTINUATION;
 136             accum |= (c & 0x3F) << 6;
 137             state = Dec4B4;
 138             break;
 139
 140         case Dec4B4:
 141             CHECK_CONTINUATION;
 142
 143             c32 = accum | (c & 0x3F);
 144
 145             // Overlong
 146             if(c32 <= 0xFFFF) FINISH(false);
 147
 148             // Not in Unicode
 149             if(c32 > 0x10FFFF) FINISH(false);
 150
 151             OUT32(c32);
 152             break;
 153
 154         default:
 155             assert(!"Invalid state");
 156         }
 157
 158         (*p_inbuf)++;
 159         (*p_insz)--;
 160     }
 161     END_CONVERSION;
 162 }
 163
 164 enum {
 165     EncStart = 0,
 166     Enc1R,
 167     Enc2R,
 168     Enc3R,
 169 };
 170
 171 static bool c32toutf8(
 172     char           *restrict *restrict  p_outbuf,
 173     size_t                   *restrict  p_outsz,
 174     const char32_t *restrict *restrict  p_inbuf,
 175     size_t                   *restrict  p_insz,
 176     mbstate_t                *restrict  p_s
 177 )
 178 {
 179     START_CONVERSION
 180     while(*p_outsz) {
 181         unsigned char outc = 0;
 182         switch(state) {
 183         case Enc3R:
 184             outc = 0x80 | ((accum >> 12) & 0x3F);
 185             state = Enc2R;
 186             break;
 187
 188         case Enc2R:
 189             outc = 0x80 | ((accum >> 6) & 0x3F);
 190             state = Enc1R;
 191             break;
 192
 193         case Enc1R:
 194             outc = 0x80 | (accum & 0x3F);
 195             state = EncStart;
 196             _PDCLIB_UNDEFINED(accum);
 197             break;
 198
 199         case EncStart:
 200             if(*p_insz == 0)
 201                 FINISH(true);
 202
 203             accum  = **p_inbuf;
 204             (*p_inbuf)++;
 205             (*p_insz)--;
 206
 207             if(accum <= 0x7F) {
 208                 outc = accum;
 209                 state = EncStart;
 210                 _PDCLIB_UNDEFINED(accum);
 211             } else if(accum <= 0x7FF) {
 212                 outc = 0xC0 | (accum >> 6);
 213                 state = Enc1R;
 214             } else if(accum <= 0xFFFF) {
 215                 outc = 0xE0 | (accum >> 12);
 216                 state = Enc2R;
 217             } else if(accum <= 0x10FFFF) {
 218                 outc = 0xF0 | (accum >> 18);
 219                 state = Enc3R;
 220             } else {
 221                 FINISH(false);
 222             }
 223             break;
 224         }
 225
 226         if(p_outbuf) {
 227             **p_outbuf = outc;
 228             (*p_outbuf)++;
 229         }
 230         (*p_outsz)--;
 231     }
 232     END_CONVERSION;
 233 }
 234
 235 const struct _PDCLIB_charcodec_t _PDCLIB_utf8_codec = {
 236     .__mbsinit   = utf8_mbsinit,
 237     .__mbstoc32s = utf8toc32,
 238     .__c32stombs = c32toutf8,
 239     .__mb_max    = 4,
 240 };
 241
 242 #endif
 243
 244 #ifdef TEST
 245 #include "_PDCLIB_test.h"
 246
 247 int main( void )
 248 {
 249 #ifndef REGTEST
 250     // Valid conversion & back
 251
 252     static const char* input = "abcde" "\xDF\xBF" "\xEF\xBF\xBF"
 253                                "\xF4\x8F\xBF\xBF";
 254
 255     char32_t c32out[8];
 256
 257     char32_t   *c32ptr = &c32out[0];
 258     size_t      c32rem = 8;
 259     const char *chrptr = (char*) &input[0];
 260     size_t      chrrem = strlen(input);
 261     mbstate_t   mbs = { 0 };
 262
 263     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs));
 264     TESTCASE(c32rem == 0);
 265     TESTCASE(chrrem == 0);
 266     TESTCASE(c32ptr == &c32out[8]);
 267     TESTCASE(chrptr == &input[strlen(input)]);
 268     TESTCASE(c32out[0] == 'a' && c32out[1] == 'b' && c32out[2] == 'c' &&
 269              c32out[3] == 'd' && c32out[4] == 'e' && c32out[5] == 0x7FF &&
 270              c32out[6] == 0xFFFF && c32out[7] == 0x10FFFF);
 271
 272     char chrout[strlen(input)];
 273     c32ptr = &c32out[0];
 274     c32rem = 8;
 275     chrptr = &chrout[0];
 276     chrrem = strlen(input);
 277     TESTCASE(c32toutf8(&chrptr, &chrrem, &c32ptr, &c32rem, &mbs));
 278     TESTCASE(c32rem == 0);
 279     TESTCASE(chrrem == 0);
 280     TESTCASE(c32ptr == &c32out[8]);
 281     TESTCASE(chrptr == &chrout[strlen(input)]);
 282     TESTCASE(memcmp(chrout, input, strlen(input)) == 0);
 283
 284     // Multi-part conversion
 285     static const char* mpinput = "\xDF\xBF";
 286     c32ptr = &c32out[0];
 287     c32rem = 8;
 288     chrptr = &mpinput[0];
 289     chrrem = 1;
 290     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs));
 291     TESTCASE(c32ptr == &c32out[0]);
 292     TESTCASE(c32rem == 8);
 293     TESTCASE(chrptr == &mpinput[1]);
 294     TESTCASE(chrrem == 0);
 295     chrrem = 1;
 296     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs));
 297     TESTCASE(c32ptr == &c32out[1]);
 298     TESTCASE(c32rem == 7);
 299     TESTCASE(chrptr == &mpinput[2]);
 300     TESTCASE(chrrem == 0);
 301
 302     // Invalid conversions
 303
 304     // Overlong nuls
 305     const char* nul2 = "\xC0\x80";
 306     c32ptr = &c32out[0];
 307     c32rem = 8;
 308     chrptr = &nul2[0];
 309     chrrem = 2;
 310     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs) == false);
 311     memset(&mbs, 0, sizeof mbs);
 312     const char* nul3 = "\xE0\x80\x80";
 313     c32ptr = &c32out[0];
 314     c32rem = 8;
 315     chrptr = &nul3[0];
 316     chrrem = 3;
 317     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs) == false);
 318     memset(&mbs, 0, sizeof mbs);
 319     const char* nul4 = "\xF0\x80\x80\x80";
 320     c32ptr = &c32out[0];
 321     c32rem = 8;
 322     chrptr = &nul4[0];
 323     chrrem = 4;
 324     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs) == false);
 325
 326     // Starting on a continuation
 327     const char* cont = "\x80";
 328     c32ptr = &c32out[0];
 329     c32rem = 8;
 330     chrptr = &cont[0];
 331     chrrem = 1;
 332     TESTCASE(utf8toc32(&c32ptr, &c32rem, &chrptr, &chrrem, &mbs) == false);
 333 #endif
 334     return TEST_RESULTS;
 335 }
 336
 337 #endif
 338