1 /* 2 ****************************************************************************** 3 * 4 * Copyright (C) 1999-2006, 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 #include "base/third_party/icu/icu_utf.h" 21 22 namespace base_icu { 23 24 /** 25 * UTF8_ERROR_VALUE_1 and UTF8_ERROR_VALUE_2 are special error values for UTF-8, 26 * which need 1 or 2 bytes in UTF-8: 27 * \code 28 * U+0015 = NAK = Negative Acknowledge, C0 control character 29 * U+009f = highest C1 control character 30 * \endcode 31 * 32 * These are used by UTF8_..._SAFE macros so that they can return an error value 33 * that needs the same number of code units (bytes) as were seen by 34 * a macro. They should be tested with UTF_IS_ERROR() or UTF_IS_VALID(). 35 * 36 * @deprecated ICU 2.4. Obsolete, see utf_old.h. 37 */ 38 #define CBUTF8_ERROR_VALUE_1 0x15 39 40 /** 41 * See documentation on UTF8_ERROR_VALUE_1 for details. 42 * 43 * @deprecated ICU 2.4. Obsolete, see utf_old.h. 44 */ 45 #define CBUTF8_ERROR_VALUE_2 0x9f 46 47 48 /** 49 * Error value for all UTFs. This code point value will be set by macros with e> 50 * checking if an error is detected. 51 * 52 * @deprecated ICU 2.4. Obsolete, see utf_old.h. 53 */ 54 #define CBUTF_ERROR_VALUE 0xffff 55 56 /* 57 * This table could be replaced on many machines by 58 * a few lines of assembler code using an 59 * "index of first 0-bit from msb" instruction and 60 * one or two more integer instructions. 61 * 62 * For example, on an i386, do something like 63 * - MOV AL, leadByte 64 * - NOT AL (8-bit, leave b15..b8==0..0, reverse only b7..b0) 65 * - MOV AH, 0 66 * - BSR BX, AX (16-bit) 67 * - MOV AX, 6 (result) 68 * - JZ finish (ZF==1 if leadByte==0xff) 69 * - SUB AX, BX (result) 70 * -finish: 71 * (BSR: Bit Scan Reverse, scans for a 1-bit, starting from the MSB) 72 * 73 * In Unicode, all UTF-8 byte sequences with more than 4 bytes are illegal; 74 * lead bytes above 0xf4 are illegal. 75 * We keep them in this table for skipping long ISO 10646-UTF-8 sequences. 76 */ 77 const uint8 78 utf8_countTrailBytes[256]={ 79 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 80 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 81 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 82 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 83 84 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 85 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 86 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 87 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 88 89 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 90 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 91 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 92 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 93 94 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 95 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 96 97 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 98 3, 3, 3, 3, 3, 99 3, 3, 3, /* illegal in Unicode */ 100 4, 4, 4, 4, /* illegal in Unicode */ 101 5, 5, /* illegal in Unicode */ 102 0, 0 /* illegal bytes 0xfe and 0xff */ 103 }; 104 105 static const UChar32 106 utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 }; 107 108 static const UChar32 109 utf8_errorValue[6]={ 110 CBUTF8_ERROR_VALUE_1, CBUTF8_ERROR_VALUE_2, CBUTF_ERROR_VALUE, 0x10ffff, 111 0x3ffffff, 0x7fffffff 112 }; 113 114 /* 115 * Handle the non-inline part of the U8_NEXT() macro and its obsolete sibling 116 * UTF8_NEXT_CHAR_SAFE(). 117 * 118 * The "strict" parameter controls the error behavior: 119 * <0 "Safe" behavior of U8_NEXT(): All illegal byte sequences yield a negative 120 * code point result. 121 * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE): 122 * All illegal byte sequences yield a positive code point such that this 123 * result code point would be encoded with the same number of bytes as 124 * the illegal sequence. 125 * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE): 126 * Same as the obsolete "safe" behavior, but non-characters are also treated 127 * like illegal sequences. 128 * 129 * The special negative (<0) value -2 is used for lenient treatment of surrogate 130 * code points as legal. Some implementations use this for roundtripping of 131 * Unicode 16-bit strings that are not well-formed UTF-16, that is, they 132 * contain unpaired surrogates. 133 * 134 * Note that a UBool is the same as an int8_t. 135 */ 136 UChar32 137 utf8_nextCharSafeBody(const uint8 *s, int32 *pi, int32 length, UChar32 c, UBool strict) { 138 int32 i=*pi; 139 uint8 count=CBU8_COUNT_TRAIL_BYTES(c); 140 if((i)+count<=(length)) { 141 uint8 trail, illegal=0; 142 143 CBU8_MASK_LEAD_BYTE((c), count); 144 /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */ 145 switch(count) { 146 /* each branch falls through to the next one */ 147 case 5: 148 case 4: 149 /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */ 150 illegal=1; 151 break; 152 case 3: 153 trail=s[(i)++]; 154 (c)=((c)<<6)|(trail&0x3f); 155 if(c<0x110) { 156 illegal|=(trail&0xc0)^0x80; 157 } else { 158 /* code point>0x10ffff, outside Unicode */ 159 illegal=1; 160 break; 161 } 162 case 2: 163 trail=s[(i)++]; 164 (c)=((c)<<6)|(trail&0x3f); 165 illegal|=(trail&0xc0)^0x80; 166 case 1: 167 trail=s[(i)++]; 168 (c)=((c)<<6)|(trail&0x3f); 169 illegal|=(trail&0xc0)^0x80; 170 break; 171 case 0: 172 if(strict>=0) { 173 return CBUTF8_ERROR_VALUE_1; 174 } else { 175 return CBU_SENTINEL; 176 } 177 /* no default branch to optimize switch() - all values are covered */ 178 } 179 180 /* 181 * All the error handling should return a value 182 * that needs count bytes so that UTF8_GET_CHAR_SAFE() works right. 183 * 184 * Starting with Unicode 3.0.1, non-shortest forms are illegal. 185 * Starting with Unicode 3.2, surrogate code points must not be 186 * encoded in UTF-8, and there are no irregular sequences any more. 187 * 188 * U8_ macros (new in ICU 2.4) return negative values for error conditions. 189 */ 190 191 /* correct sequence - all trail bytes have (b7..b6)==(10)? */ 192 /* illegal is also set if count>=4 */ 193 if(illegal || (c)<utf8_minLegal[count] || (CBU_IS_SURROGATE(c) && strict!=-2)) { 194 /* error handling */ 195 uint8 errorCount=count; 196 /* don't go beyond this sequence */ 197 i=*pi; 198 while(count>0 && CBU8_IS_TRAIL(s[i])) { 199 ++(i); 200 --count; 201 } 202 if(strict>=0) { 203 c=utf8_errorValue[errorCount-count]; 204 } else { 205 c=CBU_SENTINEL; 206 } 207 } else if((strict)>0 && CBU_IS_UNICODE_NONCHAR(c)) { 208 /* strict: forbid non-characters like U+fffe */ 209 c=utf8_errorValue[count]; 210 } 211 } else /* too few bytes left */ { 212 /* error handling */ 213 int32 i0=i; 214 /* don't just set (i)=(length) in case there is an illegal sequence */ 215 while((i)<(length) && CBU8_IS_TRAIL(s[i])) { 216 ++(i); 217 } 218 if(strict>=0) { 219 c=utf8_errorValue[i-i0]; 220 } else { 221 c=CBU_SENTINEL; 222 } 223 } 224 *pi=i; 225 return c; 226 } 227 228 } // namespace base_icu 229
