1 /* $NetBSD: mbrtoc8.c,v 1.8 2024/08/21 18:36:11 rillig Exp $ */ 2 3 /*- 4 * Copyright (c) 2024 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * mbrtoc8(&c8, s, n, ps) 31 * 32 * Decode a Unicode scalar value from up to n bytes out of the 33 * multibyte string s, using multibyte encoding state ps, and 34 * store the next code unit in the UTF-8 representation of that 35 * scalar value at c8. 36 * 37 * If the UTF-8 representation of that scalar value is multiple 38 * bytes long, mbrtoc8 will yield the leading byte in one call that 39 * consumes input, and will yield the trailing bytes in subsequent 40 * calls without consuming any input and returning (size_t)-3 41 * instead. 42 * 43 * Return the number of bytes consumed on success, or: 44 * 45 * - 0 if the code unit is NUL, or 46 * - (size_t)-3 if a trailing byte was returned without consuming 47 * any additional input, or 48 * - (size_t)-2 if the input is incomplete, or 49 * - (size_t)-1 on error with errno set to EILSEQ. 50 * 51 * In the case of incomplete input, the decoding state so far 52 * after processing s[0], s[1], ..., s[n - 1] is saved in ps, so 53 * subsequent calls to mbrtoc8 will pick up n bytes later into 54 * the input stream. 55 * 56 * References: 57 * 58 * The Unicode Standard, Version 15.0 -- Core Specification, The 59 * Unicode Consortium, Sec. 3.8 `Surrogates', p. 118. 60 * https://www.unicode.org/versions/Unicode15.0.0/UnicodeStandard-15.0.pdf#page=144 61 * https://web.archive.org/web/20240718101254/https://www.unicode.org/versions/Unicode15.0.0/UnicodeStandard-15.0.pdf#page=144 62 * 63 * The Unicode Standard, Version 15.0 -- Core Specification, The 64 * Unicode Consortium, Sec. 3.9 `Unicode Encoding Forms': UTF-8, 65 * p. 124. 66 * https://www.unicode.org/versions/Unicode15.0.0/UnicodeStandard-15.0.pdf#page=150 67 * https://web.archive.org/web/20240718101254/https://www.unicode.org/versions/Unicode15.0.0/UnicodeStandard-15.0.pdf#page=150 68 * 69 * F. Yergeau, `UTF-8, a transformation format of ISO 10646', 70 * RFC 3629, Internet Engineering Task Force, November 2003. 71 * https://datatracker.ietf.org/doc/html/rfc3629 72 */ 73 74 #include <sys/cdefs.h> 75 __RCSID("$NetBSD: mbrtoc8.c,v 1.8 2024/08/21 18:36:11 rillig Exp $"); 76 77 #include "namespace.h" 78 79 #include <assert.h> 80 #include <errno.h> 81 #include <locale.h> 82 #include <stdalign.h> 83 #include <stddef.h> 84 #include <uchar.h> 85 86 #include "mbrtoc32.h" 87 #include "setlocale_local.h" 88 89 struct mbrtoc8state { 90 char8_t nleft; 91 char8_t buf[3]; 92 mbstate_t mbs; 93 }; 94 __CTASSERT(offsetof(struct mbrtoc8state, mbs) <= sizeof(mbstate_t)); 95 __CTASSERT(sizeof(struct mbrtoc32state) <= sizeof(mbstate_t) - 96 offsetof(struct mbrtoc8state, mbs)); 97 __CTASSERT(alignof(struct mbrtoc8state) <= alignof(mbstate_t)); 98 99 #ifdef __weak_alias 100 __weak_alias(mbrtoc8_l,_mbrtoc8_l) 101 #endif 102 103 size_t 104 mbrtoc8(char8_t *restrict pc8, const char *restrict s, size_t n, 105 mbstate_t *restrict ps) 106 { 107 108 return mbrtoc8_l(pc8, s, n, ps, _current_locale()); 109 } 110 111 size_t 112 mbrtoc8_l(char8_t *restrict pc8, const char *restrict s, size_t n, 113 mbstate_t *restrict ps, locale_t restrict loc) 114 { 115 static mbstate_t psbuf; 116 struct mbrtoc8state *S; 117 char32_t c32; 118 size_t len; 119 120 /* 121 * `If ps is a null pointer, each function uses its own 122 * internal mbstate_t object instead, which is initialized at 123 * program startup to the initial conversion state; the 124 * functions are not required to avoid data races with other 125 * calls to the same function in this case. The 126 * implementation behaves as if no library function calls 127 * these functions with a null pointer for ps.' 128 */ 129 if (ps == NULL) 130 ps = &psbuf; 131 132 /* 133 * `If s is a null pointer, the mbrtoc8 function is equivalent 134 * to the call: 135 * 136 * mbrtoc8(NULL, "", 1, ps) 137 * 138 * In this case, the values of the parameters pc8 and n are 139 * ignored.' 140 */ 141 if (s == NULL) { 142 pc8 = NULL; 143 s = ""; 144 n = 1; 145 } 146 147 /* 148 * Get the private conversion state. 149 */ 150 S = (struct mbrtoc8state *)(void *)ps; 151 152 /* 153 * If there are pending trailing bytes, yield them and return 154 * (size_t)-3 to indicate that no bytes of input were consumed. 155 */ 156 if (S->nleft) { 157 if (pc8) 158 *pc8 = S->buf[sizeof(S->buf) - S->nleft]; 159 S->buf[sizeof(S->buf) - S->nleft] = 0; /* paranoia */ 160 S->nleft--; 161 return (size_t)-3; 162 } 163 164 /* 165 * Consume the next scalar value. If no full scalar value can 166 * be obtained, stop here. 167 */ 168 len = mbrtoc32_l(&c32, s, n, &S->mbs, loc); 169 switch (len) { 170 case 0: /* NUL */ 171 if (pc8) 172 *pc8 = 0; 173 return 0; 174 case (size_t)-2: /* still incomplete after n bytes */ 175 case (size_t)-1: /* error */ 176 return len; 177 default: /* consumed len bytes of input */ 178 break; 179 } 180 181 /* 182 * We consumed a scalar value from the input. 183 * 184 * Encode it as UTF-8, yield the leading byte, and buffer the 185 * trailing bytes to yield later. 186 * 187 * Table 3-6: UTF-8 Bit Distribution 188 * Table 3-7: Well-Formed UTF-8 Byte Sequences 189 */ 190 switch (c32) { 191 case 0x00 ... 0x7f: 192 if (pc8) 193 *pc8 = c32; 194 _DIAGASSERT(S->nleft == 0); 195 break; 196 case 0x0080 ... 0x07ff: 197 if (pc8) 198 *pc8 = 0xc0 | __SHIFTOUT(c32, __BITS(10,6)); 199 S->buf[2] = 0x80 | __SHIFTOUT(c32, __BITS(5,0)); 200 S->nleft = 1; 201 break; 202 case 0x0800 ... 0xffff: 203 if (pc8) 204 *pc8 = 0xe0 | __SHIFTOUT(c32, __BITS(15,12)); 205 S->buf[1] = 0x80 | __SHIFTOUT(c32, __BITS(11,6)); 206 S->buf[2] = 0x80 | __SHIFTOUT(c32, __BITS(5,0)); 207 S->nleft = 2; 208 break; 209 case 0x10000 ... 0x10ffff: 210 if (pc8) 211 *pc8 = 0xf0 | __SHIFTOUT(c32, __BITS(20,18)); 212 S->buf[0] = 0x80 | __SHIFTOUT(c32, __BITS(17,12)); 213 S->buf[1] = 0x80 | __SHIFTOUT(c32, __BITS(11,6)); 214 S->buf[2] = 0x80 | __SHIFTOUT(c32, __BITS(5,0)); 215 S->nleft = 3; 216 break; 217 default: 218 errno = EILSEQ; 219 return (size_t)-1; 220 } 221 222 /* 223 * Return the number of bytes consumed from the input. 224 */ 225 return len; 226 } 227
Indexes created Sat Sep 20 22:09:52 GMT 2025