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 <stdarg.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <string.h> 34 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 35 # include <vis.h> 36 #endif 37 #ifdef HAVE_WCHAR_H 38 # include <wchar.h> 39 #endif 40 41 #include "utf8.h" 42 43 static int dangerous_locale(void); 44 static int grow_dst(char **, size_t *, size_t, char **, size_t); 45 static int vasnmprintf(char **, size_t, int *, const char *, va_list); 46 47 48 /* 49 * For US-ASCII and UTF-8 encodings, we can safely recover from 50 * encoding errors and from non-printable characters. For any 51 * other encodings, err to the side of caution and abort parsing: 52 * For state-dependent encodings, recovery is impossible. 53 * For arbitrary encodings, replacement of non-printable 54 * characters would be non-trivial and too fragile. 55 */ 56 57 static int 58 dangerous_locale(void) { 59 char *loc; 60 61 loc = nl_langinfo(CODESET); 62 return strcmp(loc, "US-ASCII") && strcmp(loc, "UTF-8"); 63 } 64 65 static int 66 grow_dst(char **dst, size_t *sz, size_t maxsz, char **dp, size_t need) 67 { 68 char *tp; 69 size_t tsz; 70 71 if (*dp + need < *dst + *sz) 72 return 0; 73 tsz = *sz + 128; 74 if (tsz > maxsz) 75 tsz = maxsz; 76 if ((tp = realloc(*dst, tsz)) == NULL) 77 return -1; 78 *dp = tp + (*dp - *dst); 79 *dst = tp; 80 *sz = tsz; 81 return 0; 82 } 83 84 /* 85 * The following two functions limit the number of bytes written, 86 * including the terminating '\0', to sz. Unless wp is NULL, 87 * they limit the number of display columns occupied to *wp. 88 * Whichever is reached first terminates the output string. 89 * To stay close to the standard interfaces, they return the number of 90 * non-NUL bytes that would have been written if both were unlimited. 91 * If wp is NULL, newline, carriage return, and tab are allowed; 92 * otherwise, the actual number of columns occupied by what was 93 * written is returned in *wp. 94 */ 95 96 static int 97 vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) 98 { 99 char *src; /* Source string returned from vasprintf. */ 100 char *sp; /* Pointer into src. */ 101 char *dst; /* Destination string to be returned. */ 102 char *dp; /* Pointer into dst. */ 103 char *tp; /* Temporary pointer for dst. */ 104 size_t sz; /* Number of bytes allocated for dst. */ 105 wchar_t wc; /* Wide character at sp. */ 106 int len; /* Number of bytes in the character at sp. */ 107 int ret; /* Number of bytes needed to format src. */ 108 int width; /* Display width of the character wc. */ 109 int total_width, max_width, print; 110 111 src = NULL; 112 if ((ret = vasprintf(&src, fmt, ap)) <= 0) 113 goto fail; 114 115 sz = strlen(src) + 1; 116 if ((dst = malloc(sz)) == NULL) { 117 free(src); 118 goto fail; 119 } 120 121 if (maxsz > INT_MAX) 122 maxsz = INT_MAX; 123 124 sp = src; 125 dp = dst; 126 ret = 0; 127 print = 1; 128 total_width = 0; 129 max_width = wp == NULL ? INT_MAX : *wp; 130 while (*sp != '\0') { 131 if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { 132 (void)mbtowc(NULL, NULL, MB_CUR_MAX); 133 if (dangerous_locale()) { 134 ret = -1; 135 break; 136 } 137 len = 1; 138 width = -1; 139 } else if (wp == NULL && 140 (wc == L'\n' || wc == L'\r' || wc == L'\t')) { 141 /* 142 * Don't use width uninitialized; the actual 143 * value doesn't matter because total_width 144 * is only returned for wp != NULL. 145 */ 146 width = 0; 147 } else if ((width = wcwidth(wc)) == -1 && 148 dangerous_locale()) { 149 ret = -1; 150 break; 151 } 152 153 /* Valid, printable character. */ 154 155 if (width >= 0) { 156 if (print && (dp - dst >= (int)maxsz - len || 157 total_width > max_width - width)) 158 print = 0; 159 if (print) { 160 if (grow_dst(&dst, &sz, maxsz, 161 &dp, len) == -1) { 162 ret = -1; 163 break; 164 } 165 total_width += width; 166 memcpy(dp, sp, len); 167 dp += len; 168 } 169 sp += len; 170 if (ret >= 0) 171 ret += len; 172 continue; 173 } 174 175 /* Escaping required. */ 176 177 while (len > 0) { 178 if (print && (dp - dst >= (int)maxsz - 4 || 179 total_width > max_width - 4)) 180 print = 0; 181 if (print) { 182 if (grow_dst(&dst, &sz, maxsz, 183 &dp, 4) == -1) { 184 ret = -1; 185 break; 186 } 187 tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); 188 width = tp - dp; 189 total_width += width; 190 dp = tp; 191 } else 192 width = 4; 193 len--; 194 sp++; 195 if (ret >= 0) 196 ret += width; 197 } 198 if (len > 0) 199 break; 200 } 201 free(src); 202 *dp = '\0'; 203 *str = dst; 204 if (wp != NULL) 205 *wp = total_width; 206 207 /* 208 * If the string was truncated by the width limit but 209 * would have fit into the size limit, the only sane way 210 * to report the problem is using the return value, such 211 * that the usual idiom "if (ret < 0 || ret >= sz) error" 212 * works as expected. 213 */ 214 215 if (ret < (int)maxsz && !print) 216 ret = -1; 217 return ret; 218 219 fail: 220 if (wp != NULL) 221 *wp = 0; 222 if (ret == 0) { 223 *str = src; 224 return 0; 225 } else { 226 *str = NULL; 227 return -1; 228 } 229 } 230 231 int 232 snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) 233 { 234 va_list ap; 235 char *cp; 236 int ret; 237 238 va_start(ap, fmt); 239 ret = vasnmprintf(&cp, sz, wp, fmt, ap); 240 va_end(ap); 241 if (cp != NULL) { 242 (void)strlcpy(str, cp, sz); 243 free(cp); 244 } else 245 *str = '\0'; 246 return ret; 247 } 248 249 /* 250 * To stay close to the standard interfaces, the following functions 251 * return the number of non-NUL bytes written. 252 */ 253 254 int 255 vfmprintf(FILE *stream, const char *fmt, va_list ap) 256 { 257 char *str; 258 int ret; 259 260 if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) 261 return -1; 262 if (fputs(str, stream) == EOF) 263 ret = -1; 264 free(str); 265 return ret; 266 } 267 268 int 269 fmprintf(FILE *stream, const char *fmt, ...) 270 { 271 va_list ap; 272 int ret; 273 274 va_start(ap, fmt); 275 ret = vfmprintf(stream, fmt, ap); 276 va_end(ap); 277 return ret; 278 } 279 280 int 281 mprintf(const char *fmt, ...) 282 { 283 va_list ap; 284 int ret; 285 286 va_start(ap, fmt); 287 ret = vfmprintf(stdout, fmt, ap); 288 va_end(ap); 289 return ret; 290 } 291