1 /* $OpenBSD: utf8.c,v 1.7 2017/05/31 09:15:42 deraadt 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") != 0 && strcmp(loc, "UTF-8") != 0 && 64 strcmp(loc, "ANSI_X3.4-1968") != 0 && strcmp(loc, "646") != 0 && 65 strcmp(loc, "") != 0; 66 } 67 68 static int 69 grow_dst(char **dst, size_t *sz, size_t maxsz, char **dp, size_t need) 70 { 71 char *tp; 72 size_t tsz; 73 74 if (*dp + need < *dst + *sz) 75 return 0; 76 tsz = *sz + 128; 77 if (tsz > maxsz) 78 tsz = maxsz; 79 if ((tp = recallocarray(*dst, *sz, tsz, 1)) == NULL) 80 return -1; 81 *dp = tp + (*dp - *dst); 82 *dst = tp; 83 *sz = tsz; 84 return 0; 85 } 86 87 /* 88 * The following two functions limit the number of bytes written, 89 * including the terminating '\0', to sz. Unless wp is NULL, 90 * they limit the number of display columns occupied to *wp. 91 * Whichever is reached first terminates the output string. 92 * To stay close to the standard interfaces, they return the number of 93 * non-NUL bytes that would have been written if both were unlimited. 94 * If wp is NULL, newline, carriage return, and tab are allowed; 95 * otherwise, the actual number of columns occupied by what was 96 * written is returned in *wp. 97 */ 98 99 static int 100 vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) 101 { 102 char *src; /* Source string returned from vasprintf. */ 103 char *sp; /* Pointer into src. */ 104 char *dst; /* Destination string to be returned. */ 105 char *dp; /* Pointer into dst. */ 106 char *tp; /* Temporary pointer for dst. */ 107 size_t sz; /* Number of bytes allocated for dst. */ 108 wchar_t wc; /* Wide character at sp. */ 109 int len; /* Number of bytes in the character at sp. */ 110 int ret; /* Number of bytes needed to format src. */ 111 int width; /* Display width of the character wc. */ 112 int total_width, max_width, print; 113 114 src = NULL; 115 if ((ret = vasprintf(&src, fmt, ap)) <= 0) 116 goto fail; 117 118 sz = strlen(src) + 1; 119 if ((dst = malloc(sz)) == NULL) { 120 free(src); 121 ret = -1; 122 goto fail; 123 } 124 125 if (maxsz > INT_MAX) 126 maxsz = INT_MAX; 127 128 sp = src; 129 dp = dst; 130 ret = 0; 131 print = 1; 132 total_width = 0; 133 max_width = wp == NULL ? INT_MAX : *wp; 134 while (*sp != '\0') { 135 if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { 136 (void)mbtowc(NULL, NULL, MB_CUR_MAX); 137 if (dangerous_locale()) { 138 ret = -1; 139 break; 140 } 141 len = 1; 142 width = -1; 143 } else if (wp == NULL && 144 (wc == L'\n' || wc == L'\r' || wc == L'\t')) { 145 /* 146 * Don't use width uninitialized; the actual 147 * value doesn't matter because total_width 148 * is only returned for wp != NULL. 149 */ 150 width = 0; 151 } else if ((width = wcwidth(wc)) == -1 && 152 dangerous_locale()) { 153 ret = -1; 154 break; 155 } 156 157 /* Valid, printable character. */ 158 159 if (width >= 0) { 160 if (print && (dp - dst >= (int)maxsz - len || 161 total_width > max_width - width)) 162 print = 0; 163 if (print) { 164 if (grow_dst(&dst, &sz, maxsz, 165 &dp, len) == -1) { 166 ret = -1; 167 break; 168 } 169 total_width += width; 170 memcpy(dp, sp, len); 171 dp += len; 172 } 173 sp += len; 174 if (ret >= 0) 175 ret += len; 176 continue; 177 } 178 179 /* Escaping required. */ 180 181 while (len > 0) { 182 if (print && (dp - dst >= (int)maxsz - 4 || 183 total_width > max_width - 4)) 184 print = 0; 185 if (print) { 186 if (grow_dst(&dst, &sz, maxsz, 187 &dp, 4) == -1) { 188 ret = -1; 189 break; 190 } 191 tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); 192 width = tp - dp; 193 total_width += width; 194 dp = tp; 195 } else 196 width = 4; 197 len--; 198 sp++; 199 if (ret >= 0) 200 ret += width; 201 } 202 if (len > 0) 203 break; 204 } 205 free(src); 206 *dp = '\0'; 207 *str = dst; 208 if (wp != NULL) 209 *wp = total_width; 210 211 /* 212 * If the string was truncated by the width limit but 213 * would have fit into the size limit, the only sane way 214 * to report the problem is using the return value, such 215 * that the usual idiom "if (ret < 0 || ret >= sz) error" 216 * works as expected. 217 */ 218 219 if (ret < (int)maxsz && !print) 220 ret = -1; 221 return ret; 222 223 fail: 224 if (wp != NULL) 225 *wp = 0; 226 if (ret == 0) { 227 *str = src; 228 return 0; 229 } else { 230 *str = NULL; 231 return -1; 232 } 233 } 234 235 int 236 snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) 237 { 238 va_list ap; 239 char *cp; 240 int ret; 241 242 va_start(ap, fmt); 243 ret = vasnmprintf(&cp, sz, wp, fmt, ap); 244 va_end(ap); 245 if (cp != NULL) { 246 (void)strlcpy(str, cp, sz); 247 free(cp); 248 } else 249 *str = '\0'; 250 return ret; 251 } 252 253 /* 254 * To stay close to the standard interfaces, the following functions 255 * return the number of non-NUL bytes written. 256 */ 257 258 int 259 vfmprintf(FILE *stream, const char *fmt, va_list ap) 260 { 261 char *str; 262 int ret; 263 264 if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) 265 return -1; 266 if (fputs(str, stream) == EOF) 267 ret = -1; 268 free(str); 269 return ret; 270 } 271 272 int 273 fmprintf(FILE *stream, const char *fmt, ...) 274 { 275 va_list ap; 276 int ret; 277 278 va_start(ap, fmt); 279 ret = vfmprintf(stream, fmt, ap); 280 va_end(ap); 281 return ret; 282 } 283 284 int 285 mprintf(const char *fmt, ...) 286 { 287 va_list ap; 288 int ret; 289 290 va_start(ap, fmt); 291 ret = vfmprintf(stdout, fmt, ap); 292 va_end(ap); 293 return ret; 294 } 295 296 /* 297 * Set up libc for multibyte output in the user's chosen locale. 298 * 299 * XXX: we are known to have problems with Turkish (i/I confusion) so we 300 * deliberately fall back to the C locale for now. Longer term we should 301 * always prefer to select C.[encoding] if possible, but there's no 302 * standardisation in locales between systems, so we'll need to survey 303 * what's out there first. 304 */ 305 void 306 msetlocale(void) 307 { 308 const char *vars[] = { "LC_ALL", "LC_CTYPE", "LANG", NULL }; 309 char *cp; 310 int i; 311 312 /* 313 * We can't yet cope with dotless/dotted I in Turkish locales, 314 * so fall back to the C locale for these. 315 */ 316 for (i = 0; vars[i] != NULL; i++) { 317 if ((cp = getenv(vars[i])) == NULL) 318 continue; 319 if (strncasecmp(cp, "TR", 2) != 0) 320 break; 321 /* 322 * If we're in a UTF-8 locale then prefer to use 323 * the C.UTF-8 locale (or equivalent) if it exists. 324 */ 325 if ((strcasestr(cp, "UTF-8") != NULL || 326 strcasestr(cp, "UTF8") != NULL) && 327 (setlocale(LC_CTYPE, "C.UTF-8") != NULL || 328 setlocale(LC_CTYPE, "POSIX.UTF-8") != NULL)) 329 return; 330 setlocale(LC_CTYPE, "C"); 331 return; 332 } 333 /* We can handle this locale */ 334 setlocale(LC_CTYPE, ""); 335 } 336