1 /* 2 ****************************************************************************** 3 * 4 * Copyright (C) 1999-2012, International Business Machines 5 * Corporation and others. All Rights Reserved. 6 * 7 ****************************************************************************** 8 * file name: utf_impl.c 9 * encoding: US-ASCII 10 * tab size: 8 (not used) 11 * indentation:4 12 * 13 * created on: 1999sep13 14 * created by: Markus W. Scherer 15 * 16 * This file provides implementation functions for macros in the utfXX.h 17 * that would otherwise be too long as macros. 18 */ 19 20 /* set import/export definitions */ 21 #ifndef U_UTF8_IMPL 22 # define U_UTF8_IMPL 23 #endif 24 25 #include "unicode/utypes.h" 26 #include "unicode/utf.h" 27 #include "unicode/utf8.h" 28 #include "unicode/utf_old.h" 29 #include "uassert.h" 30 31 /* 32 * This table could be replaced on many machines by 33 * a few lines of assembler code using an 34 * "index of first 0-bit from msb" instruction and 35 * one or two more integer instructions. 36 * 37 * For example, on an i386, do something like 38 * - MOV AL, leadByte 39 * - NOT AL (8-bit, leave b15..b8==0..0, reverse only b7..b0) 40 * - MOV AH, 0 41 * - BSR BX, AX (16-bit) 42 * - MOV AX, 6 (result) 43 * - JZ finish (ZF==1 if leadByte==0xff) 44 * - SUB AX, BX (result) 45 * -finish: 46 * (BSR: Bit Scan Reverse, scans for a 1-bit, starting from the MSB) 47 * 48 * In Unicode, all UTF-8 byte sequences with more than 4 bytes are illegal; 49 * lead bytes above 0xf4 are illegal. 50 * We keep them in this table for skipping long ISO 10646-UTF-8 sequences. 51 */ 52 U_EXPORT const uint8_t 53 utf8_countTrailBytes[256]={ 54 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 55 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 56 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 57 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 58 59 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 60 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 61 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 63 64 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 66 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 67 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 68 69 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 70 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 71 72 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 73 3, 3, 3, 3, 3, 74 3, 3, 3, /* illegal in Unicode */ 75 4, 4, 4, 4, /* illegal in Unicode */ 76 5, 5, /* illegal in Unicode */ 77 0, 0 /* illegal bytes 0xfe and 0xff */ 78 }; 79 80 static const UChar32 81 utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 }; 82 83 static const UChar32 84 utf8_errorValue[6]={ 85 UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE, 0x10ffff, 86 0x3ffffff, 0x7fffffff 87 }; 88 89 static UChar32 90 errorValue(int32_t count, int8_t strict) { 91 if(strict>=0) { 92 return utf8_errorValue[count]; 93 } else if(strict==-3) { 94 return 0xfffd; 95 } else { 96 return U_SENTINEL; 97 } 98 } 99 100 /* 101 * Handle the non-inline part of the U8_NEXT() and U8_NEXT_FFFD() macros 102 * and their obsolete sibling UTF8_NEXT_CHAR_SAFE(). 103 * 104 * U8_NEXT() supports NUL-terminated strings indicated via length<0. 105 * 106 * The "strict" parameter controls the error behavior: 107 * <0 "Safe" behavior of U8_NEXT(): 108 * -1: All illegal byte sequences yield U_SENTINEL=-1. 109 * -2: Same as -1, except for lenient treatment of surrogate code points as legal. 110 * Some implementations use this for roundtripping of 111 * Unicode 16-bit strings that are not well-formed UTF-16, that is, they 112 * contain unpaired surrogates. 113 * -3: All illegal byte sequences yield U+FFFD. 114 * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE): 115 * All illegal byte sequences yield a positive code point such that this 116 * result code point would be encoded with the same number of bytes as 117 * the illegal sequence. 118 * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE): 119 * Same as the obsolete "safe" behavior, but non-characters are also treated 120 * like illegal sequences. 121 * 122 * Note that a UBool is the same as an int8_t. 123 */ 124 U_CAPI UChar32 U_EXPORT2 125 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict) { 126 int32_t i=*pi; 127 uint8_t count=U8_COUNT_TRAIL_BYTES(c); 128 U_ASSERT(count <= 5); /* U8_COUNT_TRAIL_BYTES returns value 0...5 */ 129 if(i+count<=length || length<0) { 130 uint8_t trail; 131 132 U8_MASK_LEAD_BYTE(c, count); 133 /* support NUL-terminated strings: do not read beyond the first non-trail byte */ 134 switch(count) { 135 /* each branch falls through to the next one */ 136 case 0: 137 /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */ 138 case 5: 139 case 4: 140 /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */ 141 break; 142 case 3: 143 trail=s[i++]-0x80; 144 c=(c<<6)|trail; 145 /* c>=0x110 would result in code point>0x10ffff, outside Unicode */ 146 if(c>=0x110 || trail>0x3f) { break; } 147 case 2: 148 trail=s[i++]-0x80; 149 c=(c<<6)|trail; 150 /* 151 * test for a surrogate d800..dfff unless we are lenient: 152 * before the last (c<<6), a surrogate is c=360..37f 153 */ 154 if(((c&0xffe0)==0x360 && strict!=-2) || trail>0x3f) { break; } 155 case 1: 156 trail=s[i++]-0x80; 157 c=(c<<6)|trail; 158 if(trail>0x3f) { break; } 159 /* correct sequence - all trail bytes have (b7..b6)==(10) */ 160 if(c>=utf8_minLegal[count] && 161 /* strict: forbid non-characters like U+fffe */ 162 (strict<=0 || !U_IS_UNICODE_NONCHAR(c))) { 163 *pi=i; 164 return c; 165 } 166 /* no default branch to optimize switch() - all values are covered */ 167 } 168 } else { 169 /* too few bytes left */ 170 count=length-i; 171 } 172 173 /* error handling */ 174 i=*pi; 175 while(count>0 && U8_IS_TRAIL(s[i])) { 176 ++i; 177 --count; 178 } 179 c=errorValue(i-*pi, strict); 180 *pi=i; 181 return c; 182 } 183 184 U_CAPI int32_t U_EXPORT2 185 utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError) { 186 if((uint32_t)(c)<=0x7ff) { 187 if((i)+1<(length)) { 188 (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); 189 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); 190 return i; 191 } 192 } else if((uint32_t)(c)<=0xffff) { 193 /* Starting with Unicode 3.2, surrogate code points must not be encoded in UTF-8. */ 194 if((i)+2<(length) && !U_IS_SURROGATE(c)) { 195 (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); 196 (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); 197 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); 198 return i; 199 } 200 } else if((uint32_t)(c)<=0x10ffff) { 201 if((i)+3<(length)) { 202 (s)[(i)++]=(uint8_t)(((c)>>18)|0xf0); 203 (s)[(i)++]=(uint8_t)((((c)>>12)&0x3f)|0x80); 204 (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); 205 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); 206 return i; 207 } 208 } 209 /* c>0x10ffff or not enough space, write an error value */ 210 if(pIsError!=NULL) { 211 *pIsError=TRUE; 212 } else { 213 length-=i; 214 if(length>0) { 215 int32_t offset; 216 if(length>3) { 217 length=3; 218 } 219 s+=i; 220 offset=0; 221 c=utf8_errorValue[length-1]; 222 UTF8_APPEND_CHAR_UNSAFE(s, offset, c); 223 i=i+offset; 224 } 225 } 226 return i; 227 } 228 229 U_CAPI UChar32 U_EXPORT2 230 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict) { 231 int32_t i=*pi; 232 uint8_t b, count=1, shift=6; 233 234 if(!U8_IS_TRAIL(c)) { return errorValue(0, strict); } 235 236 /* extract value bits from the last trail byte */ 237 c&=0x3f; 238 239 for(;;) { 240 if(i<=start) { 241 /* no lead byte at all */ 242 return errorValue(0, strict); 243 } 244 245 /* read another previous byte */ 246 b=s[--i]; 247 if((uint8_t)(b-0x80)<0x7e) { /* 0x80<=b<0xfe */ 248 if(b&0x40) { 249 /* lead byte, this will always end the loop */ 250 uint8_t shouldCount=U8_COUNT_TRAIL_BYTES(b); 251 252 if(count==shouldCount) { 253 /* set the new position */ 254 *pi=i; 255 U8_MASK_LEAD_BYTE(b, count); 256 c|=(UChar32)b<<shift; 257 if(count>=4 || c>0x10ffff || c<utf8_minLegal[count] || (U_IS_SURROGATE(c) && strict!=-2) || (strict>0 && U_IS_UNICODE_NONCHAR(c))) { 258 /* illegal sequence or (strict and non-character) */ 259 if(count>=4) { 260 count=3; 261 } 262 c=errorValue(count, strict); 263 } else { 264 /* exit with correct c */ 265 } 266 } else { 267 /* the lead byte does not match the number of trail bytes */ 268 /* only set the position to the lead byte if it would 269 include the trail byte that we started with */ 270 if(count<shouldCount) { 271 *pi=i; 272 c=errorValue(count, strict); 273 } else { 274 c=errorValue(0, strict); 275 } 276 } 277 break; 278 } else if(count<5) { 279 /* trail byte */ 280 c|=(UChar32)(b&0x3f)<<shift; 281 ++count; 282 shift+=6; 283 } else { 284 /* more than 5 trail bytes is illegal */ 285 c=errorValue(0, strict); 286 break; 287 } 288 } else { 289 /* single-byte character precedes trailing bytes */ 290 c=errorValue(0, strict); 291 break; 292 } 293 } 294 return c; 295 } 296 297 U_CAPI int32_t U_EXPORT2 298 utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i) { 299 /* i had been decremented once before the function call */ 300 int32_t I=i, Z; 301 uint8_t b; 302 303 /* read at most the 6 bytes s[Z] to s[i], inclusively */ 304 if(I-5>start) { 305 Z=I-5; 306 } else { 307 Z=start; 308 } 309 310 /* return I if the sequence starting there is long enough to include i */ 311 do { 312 b=s[I]; 313 if((uint8_t)(b-0x80)>=0x7e) { /* not 0x80<=b<0xfe */ 314 break; 315 } else if(b>=0xc0) { 316 if(U8_COUNT_TRAIL_BYTES(b)>=(i-I)) { 317 return I; 318 } else { 319 break; 320 } 321 } 322 } while(Z<=--I); 323 324 /* return i itself to be consistent with the FWD_1 macro */ 325 return i; 326 } 327
