1 /* $OpenBSD: utf8.c,v 1.5 2017/02/19 00:10:57 djm 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 <sys/types.h> 24 #include <langinfo.h> 25 #include <limits.h> 26 #include <stdarg.h> 27 #include <stdio.h> 28 #include <stdlib.h> 29 #include <string.h> 30 #include <vis.h> 31 #include <wchar.h> 32 33 #include "utf8.h" 34 35 static int dangerous_locale(void); 36 static int grow_dst(char **, size_t *, size_t, char **, size_t); 37 static int vasnmprintf(char **, size_t, int *, const char *, va_list); 38 39 40 /* 41 * For US-ASCII and UTF-8 encodings, we can safely recover from 42 * encoding errors and from non-printable characters. For any 43 * other encodings, err to the side of caution and abort parsing: 44 * For state-dependent encodings, recovery is impossible. 45 * For arbitrary encodings, replacement of non-printable 46 * characters would be non-trivial and too fragile. 47 */ 48 49 static int 50 dangerous_locale(void) { 51 char *loc; 52 53 loc = nl_langinfo(CODESET); 54 return strcmp(loc, "US-ASCII") != 0 && strcmp(loc, "UTF-8") != 0 && 55 strcmp(loc, "ANSI_X3.4-1968") != 0; 56 } 57 58 static int 59 grow_dst(char **dst, size_t *sz, size_t maxsz, char **dp, size_t need) 60 { 61 char *tp; 62 size_t tsz; 63 64 if (*dp + need < *dst + *sz) 65 return 0; 66 tsz = *sz + 128; 67 if (tsz > maxsz) 68 tsz = maxsz; 69 if ((tp = realloc(*dst, tsz)) == NULL) 70 return -1; 71 *dp = tp + (*dp - *dst); 72 *dst = tp; 73 *sz = tsz; 74 return 0; 75 } 76 77 /* 78 * The following two functions limit the number of bytes written, 79 * including the terminating '\0', to sz. Unless wp is NULL, 80 * they limit the number of display columns occupied to *wp. 81 * Whichever is reached first terminates the output string. 82 * To stay close to the standard interfaces, they return the number of 83 * non-NUL bytes that would have been written if both were unlimited. 84 * If wp is NULL, newline, carriage return, and tab are allowed; 85 * otherwise, the actual number of columns occupied by what was 86 * written is returned in *wp. 87 */ 88 89 static int 90 vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) 91 { 92 char *src; /* Source string returned from vasprintf. */ 93 char *sp; /* Pointer into src. */ 94 char *dst; /* Destination string to be returned. */ 95 char *dp; /* Pointer into dst. */ 96 char *tp; /* Temporary pointer for dst. */ 97 size_t sz; /* Number of bytes allocated for dst. */ 98 wchar_t wc; /* Wide character at sp. */ 99 int len; /* Number of bytes in the character at sp. */ 100 int ret; /* Number of bytes needed to format src. */ 101 int width; /* Display width of the character wc. */ 102 int total_width, max_width, print; 103 104 src = NULL; 105 if ((ret = vasprintf(&src, fmt, ap)) <= 0) 106 goto fail; 107 108 sz = strlen(src) + 1; 109 if ((dst = malloc(sz)) == NULL) { 110 free(src); 111 ret = -1; 112 goto fail; 113 } 114 115 if (maxsz > INT_MAX) 116 maxsz = INT_MAX; 117 118 sp = src; 119 dp = dst; 120 ret = 0; 121 print = 1; 122 total_width = 0; 123 max_width = wp == NULL ? INT_MAX : *wp; 124 while (*sp != '\0') { 125 if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { 126 (void)mbtowc(NULL, NULL, MB_CUR_MAX); 127 if (dangerous_locale()) { 128 ret = -1; 129 break; 130 } 131 len = 1; 132 width = -1; 133 } else if (wp == NULL && 134 (wc == L'\n' || wc == L'\r' || wc == L'\t')) { 135 /* 136 * Don't use width uninitialized; the actual 137 * value doesn't matter because total_width 138 * is only returned for wp != NULL. 139 */ 140 width = 0; 141 } else if ((width = wcwidth(wc)) == -1 && 142 dangerous_locale()) { 143 ret = -1; 144 break; 145 } 146 147 /* Valid, printable character. */ 148 149 if (width >= 0) { 150 if (print && (dp - dst >= (int)maxsz - len || 151 total_width > max_width - width)) 152 print = 0; 153 if (print) { 154 if (grow_dst(&dst, &sz, maxsz, 155 &dp, len) == -1) { 156 ret = -1; 157 break; 158 } 159 total_width += width; 160 memcpy(dp, sp, len); 161 dp += len; 162 } 163 sp += len; 164 if (ret >= 0) 165 ret += len; 166 continue; 167 } 168 169 /* Escaping required. */ 170 171 while (len > 0) { 172 if (print && (dp - dst >= (int)maxsz - 4 || 173 total_width > max_width - 4)) 174 print = 0; 175 if (print) { 176 if (grow_dst(&dst, &sz, maxsz, 177 &dp, 4) == -1) { 178 ret = -1; 179 break; 180 } 181 tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); 182 width = tp - dp; 183 total_width += width; 184 dp = tp; 185 } else 186 width = 4; 187 len--; 188 sp++; 189 if (ret >= 0) 190 ret += width; 191 } 192 if (len > 0) 193 break; 194 } 195 free(src); 196 *dp = '\0'; 197 *str = dst; 198 if (wp != NULL) 199 *wp = total_width; 200 201 /* 202 * If the string was truncated by the width limit but 203 * would have fit into the size limit, the only sane way 204 * to report the problem is using the return value, such 205 * that the usual idiom "if (ret < 0 || ret >= sz) error" 206 * works as expected. 207 */ 208 209 if (ret < (int)maxsz && !print) 210 ret = -1; 211 return ret; 212 213 fail: 214 if (wp != NULL) 215 *wp = 0; 216 if (ret == 0) { 217 *str = src; 218 return 0; 219 } else { 220 *str = NULL; 221 return -1; 222 } 223 } 224 225 int 226 snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) 227 { 228 va_list ap; 229 char *cp; 230 int ret; 231 232 va_start(ap, fmt); 233 ret = vasnmprintf(&cp, sz, wp, fmt, ap); 234 va_end(ap); 235 if (cp != NULL) { 236 (void)strlcpy(str, cp, sz); 237 free(cp); 238 } else 239 *str = '\0'; 240 return ret; 241 } 242 243 /* 244 * To stay close to the standard interfaces, the following functions 245 * return the number of non-NUL bytes written. 246 */ 247 248 int 249 vfmprintf(FILE *stream, const char *fmt, va_list ap) 250 { 251 char *str; 252 int ret; 253 254 if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) 255 return -1; 256 if (fputs(str, stream) == EOF) 257 ret = -1; 258 free(str); 259 return ret; 260 } 261 262 int 263 fmprintf(FILE *stream, const char *fmt, ...) 264 { 265 va_list ap; 266 int ret; 267 268 va_start(ap, fmt); 269 ret = vfmprintf(stream, fmt, ap); 270 va_end(ap); 271 return ret; 272 } 273 274 int 275 mprintf(const char *fmt, ...) 276 { 277 va_list ap; 278 int ret; 279 280 va_start(ap, fmt); 281 ret = vfmprintf(stdout, fmt, ap); 282 va_end(ap); 283 return ret; 284 } 285