1 /* $OpenBSD: utf8.c,v 1.3 2016/05/30 12:57:21 schwarze Exp $ */ 2 /* 3 * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* 19 * Utility functions for multibyte-character handling, 20 * in particular to sanitize untrusted strings for terminal output. 21 */ 22 23 #include "includes.h" 24 25 #include <sys/types.h> 26 #ifdef HAVE_LANGINFO_H 27 # include <langinfo.h> 28 #endif 29 #include <limits.h> 30 #include <locale.h> 31 #include <stdarg.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <string.h> 35 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 36 # include <vis.h> 37 #endif 38 #ifdef HAVE_WCHAR_H 39 # include <wchar.h> 40 #endif 41 42 #include "utf8.h" 43 44 static int dangerous_locale(void); 45 static int grow_dst(char **, size_t *, size_t, char **, size_t); 46 static int vasnmprintf(char **, size_t, int *, const char *, va_list); 47 48 49 /* 50 * For US-ASCII and UTF-8 encodings, we can safely recover from 51 * encoding errors and from non-printable characters. For any 52 * other encodings, err to the side of caution and abort parsing: 53 * For state-dependent encodings, recovery is impossible. 54 * For arbitrary encodings, replacement of non-printable 55 * characters would be non-trivial and too fragile. 56 */ 57 58 static int 59 dangerous_locale(void) { 60 char *loc; 61 62 loc = nl_langinfo(CODESET); 63 return strcmp(loc, "US-ASCII") && strcmp(loc, "UTF-8"); 64 } 65 66 static int 67 grow_dst(char **dst, size_t *sz, size_t maxsz, char **dp, size_t need) 68 { 69 char *tp; 70 size_t tsz; 71 72 if (*dp + need < *dst + *sz) 73 return 0; 74 tsz = *sz + 128; 75 if (tsz > maxsz) 76 tsz = maxsz; 77 if ((tp = realloc(*dst, tsz)) == NULL) 78 return -1; 79 *dp = tp + (*dp - *dst); 80 *dst = tp; 81 *sz = tsz; 82 return 0; 83 } 84 85 /* 86 * The following two functions limit the number of bytes written, 87 * including the terminating '\0', to sz. Unless wp is NULL, 88 * they limit the number of display columns occupied to *wp. 89 * Whichever is reached first terminates the output string. 90 * To stay close to the standard interfaces, they return the number of 91 * non-NUL bytes that would have been written if both were unlimited. 92 * If wp is NULL, newline, carriage return, and tab are allowed; 93 * otherwise, the actual number of columns occupied by what was 94 * written is returned in *wp. 95 */ 96 97 static int 98 vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) 99 { 100 char *src; /* Source string returned from vasprintf. */ 101 char *sp; /* Pointer into src. */ 102 char *dst; /* Destination string to be returned. */ 103 char *dp; /* Pointer into dst. */ 104 char *tp; /* Temporary pointer for dst. */ 105 size_t sz; /* Number of bytes allocated for dst. */ 106 wchar_t wc; /* Wide character at sp. */ 107 int len; /* Number of bytes in the character at sp. */ 108 int ret; /* Number of bytes needed to format src. */ 109 int width; /* Display width of the character wc. */ 110 int total_width, max_width, print; 111 112 src = NULL; 113 if ((ret = vasprintf(&src, fmt, ap)) <= 0) 114 goto fail; 115 116 sz = strlen(src) + 1; 117 if ((dst = malloc(sz)) == NULL) { 118 free(src); 119 goto fail; 120 } 121 122 if (maxsz > INT_MAX) 123 maxsz = INT_MAX; 124 125 sp = src; 126 dp = dst; 127 ret = 0; 128 print = 1; 129 total_width = 0; 130 max_width = wp == NULL ? INT_MAX : *wp; 131 while (*sp != '\0') { 132 if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { 133 (void)mbtowc(NULL, NULL, MB_CUR_MAX); 134 if (dangerous_locale()) { 135 ret = -1; 136 break; 137 } 138 len = 1; 139 width = -1; 140 } else if (wp == NULL && 141 (wc == L'\n' || wc == L'\r' || wc == L'\t')) { 142 /* 143 * Don't use width uninitialized; the actual 144 * value doesn't matter because total_width 145 * is only returned for wp != NULL. 146 */ 147 width = 0; 148 } else if ((width = wcwidth(wc)) == -1 && 149 dangerous_locale()) { 150 ret = -1; 151 break; 152 } 153 154 /* Valid, printable character. */ 155 156 if (width >= 0) { 157 if (print && (dp - dst >= (int)maxsz - len || 158 total_width > max_width - width)) 159 print = 0; 160 if (print) { 161 if (grow_dst(&dst, &sz, maxsz, 162 &dp, len) == -1) { 163 ret = -1; 164 break; 165 } 166 total_width += width; 167 memcpy(dp, sp, len); 168 dp += len; 169 } 170 sp += len; 171 if (ret >= 0) 172 ret += len; 173 continue; 174 } 175 176 /* Escaping required. */ 177 178 while (len > 0) { 179 if (print && (dp - dst >= (int)maxsz - 4 || 180 total_width > max_width - 4)) 181 print = 0; 182 if (print) { 183 if (grow_dst(&dst, &sz, maxsz, 184 &dp, 4) == -1) { 185 ret = -1; 186 break; 187 } 188 tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); 189 width = tp - dp; 190 total_width += width; 191 dp = tp; 192 } else 193 width = 4; 194 len--; 195 sp++; 196 if (ret >= 0) 197 ret += width; 198 } 199 if (len > 0) 200 break; 201 } 202 free(src); 203 *dp = '\0'; 204 *str = dst; 205 if (wp != NULL) 206 *wp = total_width; 207 208 /* 209 * If the string was truncated by the width limit but 210 * would have fit into the size limit, the only sane way 211 * to report the problem is using the return value, such 212 * that the usual idiom "if (ret < 0 || ret >= sz) error" 213 * works as expected. 214 */ 215 216 if (ret < (int)maxsz && !print) 217 ret = -1; 218 return ret; 219 220 fail: 221 if (wp != NULL) 222 *wp = 0; 223 if (ret == 0) { 224 *str = src; 225 return 0; 226 } else { 227 *str = NULL; 228 return -1; 229 } 230 } 231 232 int 233 snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) 234 { 235 va_list ap; 236 char *cp; 237 int ret; 238 239 va_start(ap, fmt); 240 ret = vasnmprintf(&cp, sz, wp, fmt, ap); 241 va_end(ap); 242 if (cp != NULL) { 243 (void)strlcpy(str, cp, sz); 244 free(cp); 245 } else 246 *str = '\0'; 247 return ret; 248 } 249 250 /* 251 * To stay close to the standard interfaces, the following functions 252 * return the number of non-NUL bytes written. 253 */ 254 255 int 256 vfmprintf(FILE *stream, const char *fmt, va_list ap) 257 { 258 char *str; 259 int ret; 260 261 if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) 262 return -1; 263 if (fputs(str, stream) == EOF) 264 ret = -1; 265 free(str); 266 return ret; 267 } 268 269 int 270 fmprintf(FILE *stream, const char *fmt, ...) 271 { 272 va_list ap; 273 int ret; 274 275 va_start(ap, fmt); 276 ret = vfmprintf(stream, fmt, ap); 277 va_end(ap); 278 return ret; 279 } 280 281 int 282 mprintf(const char *fmt, ...) 283 { 284 va_list ap; 285 int ret; 286 287 va_start(ap, fmt); 288 ret = vfmprintf(stdout, fmt, ap); 289 va_end(ap); 290 return ret; 291 } 292 293 /* 294 * Set up libc for multibyte output in the user's chosen locale. 295 * 296 * XXX: we are known to have problems with Turkish (i/I confusion) so we 297 * deliberately fall back to the C locale for now. Longer term we should 298 * always prefer to select C.[encoding] if possible, but there's no 299 * standardisation in locales between systems, so we'll need to survey 300 * what's out there first. 301 */ 302 void 303 msetlocale(void) 304 { 305 const char *vars[] = { "LC_ALL", "LC_CTYPE", "LANG", NULL }; 306 char *cp; 307 int i; 308 309 /* 310 * We can't yet cope with dotless/dotted I in Turkish locales, 311 * so fall back to the C locale for these. 312 */ 313 for (i = 0; vars[i] != NULL; i++) { 314 if ((cp = getenv(vars[i])) == NULL) 315 continue; 316 if (strncasecmp(cp, "TR", 2) != 0) 317 break; 318 /* 319 * If we're in a UTF-8 locale then prefer to use 320 * the C.UTF-8 locale (or equivalent) if it exists. 321 */ 322 if ((strcasestr(cp, "UTF-8") != NULL || 323 strcasestr(cp, "UTF8") != NULL) && 324 (setlocale(LC_CTYPE, "C.UTF-8") != NULL || 325 setlocale(LC_CTYPE, "POSIX.UTF-8") != NULL)) 326 return; 327 setlocale(LC_CTYPE, "C"); 328 return; 329 } 330 /* We can handle this locale */ 331 setlocale(LC_CTYPE, ""); 332 } 333