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_t utf8_countTrailBytes[256] = 78 { 79 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 0, 0, 81 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 82 83 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 84 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 86 87 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 88 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 89 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 90 91 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 92 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 93 94 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 95 3, 3, /* illegal in Unicode */ 96 4, 4, 4, 4, /* illegal in Unicode */ 97 5, 5, /* illegal in Unicode */ 98 0, 0 /* illegal bytes 0xfe and 0xff */ 99 }; 100 101 static const UChar32 102 utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 }; 103 104 static const UChar32 105 utf8_errorValue[6]={ 106 CBUTF8_ERROR_VALUE_1, CBUTF8_ERROR_VALUE_2, CBUTF_ERROR_VALUE, 0x10ffff, 107 0x3ffffff, 0x7fffffff 108 }; 109 110 /* 111 * Handle the non-inline part of the U8_NEXT() macro and its obsolete sibling 112 * UTF8_NEXT_CHAR_SAFE(). 113 * 114 * The "strict" parameter controls the error behavior: 115 * <0 "Safe" behavior of U8_NEXT(): All illegal byte sequences yield a negative 116 * code point result. 117 * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE): 118 * All illegal byte sequences yield a positive code point such that this 119 * result code point would be encoded with the same number of bytes as 120 * the illegal sequence. 121 * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE): 122 * Same as the obsolete "safe" behavior, but non-characters are also treated 123 * like illegal sequences. 124 * 125 * The special negative (<0) value -2 is used for lenient treatment of surrogate 126 * code points as legal. Some implementations use this for roundtripping of 127 * Unicode 16-bit strings that are not well-formed UTF-16, that is, they 128 * contain unpaired surrogates. 129 * 130 * Note that a UBool is the same as an int8_t. 131 */ 132 UChar32 utf8_nextCharSafeBody(const uint8_t* s, 133 int32_t* pi, 134 int32_t length, 135 UChar32 c, 136 UBool strict) { 137 int32_t i = *pi; 138 uint8_t count = CBU8_COUNT_TRAIL_BYTES(c); 139 if((i)+count<=(length)) { 140 uint8_t trail, illegal = 0; 141 142 CBU8_MASK_LEAD_BYTE((c), count); 143 /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */ 144 switch(count) { 145 /* each branch falls through to the next one */ 146 case 5: 147 case 4: 148 /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */ 149 illegal=1; 150 break; 151 case 3: 152 trail=s[(i)++]; 153 (c)=((c)<<6)|(trail&0x3f); 154 if(c<0x110) { 155 illegal|=(trail&0xc0)^0x80; 156 } else { 157 /* code point>0x10ffff, outside Unicode */ 158 illegal=1; 159 break; 160 } 161 case 2: 162 trail=s[(i)++]; 163 (c)=((c)<<6)|(trail&0x3f); 164 illegal|=(trail&0xc0)^0x80; 165 case 1: 166 trail=s[(i)++]; 167 (c)=((c)<<6)|(trail&0x3f); 168 illegal|=(trail&0xc0)^0x80; 169 break; 170 case 0: 171 if(strict>=0) { 172 return CBUTF8_ERROR_VALUE_1; 173 } else { 174 return CBU_SENTINEL; 175 } 176 /* no default branch to optimize switch() - all values are covered */ 177 } 178 179 /* 180 * All the error handling should return a value 181 * that needs count bytes so that UTF8_GET_CHAR_SAFE() works right. 182 * 183 * Starting with Unicode 3.0.1, non-shortest forms are illegal. 184 * Starting with Unicode 3.2, surrogate code points must not be 185 * encoded in UTF-8, and there are no irregular sequences any more. 186 * 187 * U8_ macros (new in ICU 2.4) return negative values for error conditions. 188 */ 189 190 /* correct sequence - all trail bytes have (b7..b6)==(10)? */ 191 /* illegal is also set if count>=4 */ 192 if(illegal || (c)<utf8_minLegal[count] || (CBU_IS_SURROGATE(c) && strict!=-2)) { 193 /* error handling */ 194 uint8_t errorCount = count; 195 /* don't go beyond this sequence */ 196 i=*pi; 197 while(count>0 && CBU8_IS_TRAIL(s[i])) { 198 ++(i); 199 --count; 200 } 201 if(strict>=0) { 202 c=utf8_errorValue[errorCount-count]; 203 } else { 204 c=CBU_SENTINEL; 205 } 206 } else if((strict)>0 && CBU_IS_UNICODE_NONCHAR(c)) { 207 /* strict: forbid non-characters like U+fffe */ 208 c=utf8_errorValue[count]; 209 } 210 } else /* too few bytes left */ { 211 /* error handling */ 212 int32_t i0 = i; 213 /* don't just set (i)=(length) in case there is an illegal sequence */ 214 while((i)<(length) && CBU8_IS_TRAIL(s[i])) { 215 ++(i); 216 } 217 if(strict>=0) { 218 c=utf8_errorValue[i-i0]; 219 } else { 220 c=CBU_SENTINEL; 221 } 222 } 223 *pi=i; 224 return c; 225 } 226 227 } // namespace base_icu 228
