schwarze@openbsd.org | 0e059cd | 2016-05-25 23:48:45 +0000 | [diff] [blame^] | 1 | /* $OpenBSD: utf8.c,v 1.1 2016/05/25 23:48:45 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 <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 vasnmprintf(char **, size_t, int *, const char *, va_list); |
| 37 | |
| 38 | |
| 39 | /* |
| 40 | * For US-ASCII and UTF-8 encodings, we can safely recover from |
| 41 | * encoding errors and from non-printable characters. For any |
| 42 | * other encodings, err to the side of caution and abort parsing: |
| 43 | * For state-dependent encodings, recovery is impossible. |
| 44 | * For arbitrary encodings, replacement of non-printable |
| 45 | * characters would be non-trivial and too fragile. |
| 46 | */ |
| 47 | |
| 48 | static int |
| 49 | dangerous_locale(void) { |
| 50 | char *loc; |
| 51 | |
| 52 | loc = nl_langinfo(CODESET); |
| 53 | return strcmp(loc, "US-ASCII") && strcmp(loc, "UTF-8"); |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * The following two functions limit the number of bytes written, |
| 58 | * including the terminating '\0', to sz. Unless wp is NULL, |
| 59 | * they limit the number of display columns occupied to *wp. |
| 60 | * Whichever is reached first terminates the output string. |
| 61 | * To stay close to the standard interfaces, they return the number of |
| 62 | * non-NUL bytes that would have been written if both were unlimited. |
| 63 | * If wp is NULL, newline, carriage return, and tab are allowed; |
| 64 | * otherwise, the actual number of columns occupied by what was |
| 65 | * written is returned in *wp. |
| 66 | */ |
| 67 | |
| 68 | static int |
| 69 | vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) |
| 70 | { |
| 71 | char *src; /* Source string returned from vasprintf. */ |
| 72 | char *sp; /* Pointer into src. */ |
| 73 | char *dst; /* Destination string to be returned. */ |
| 74 | char *dp; /* Pointer into dst. */ |
| 75 | char *tp; /* Temporary pointer for dst. */ |
| 76 | size_t sz; /* Number of bytes allocated for dst. */ |
| 77 | size_t tsz; /* Temporary size while extending dst. */ |
| 78 | wchar_t wc; /* Wide character at sp. */ |
| 79 | int len; /* Number of bytes in the character at sp. */ |
| 80 | int ret; /* Number of bytes needed to format src. */ |
| 81 | int width; /* Display width of the character wc. */ |
| 82 | int total_width, max_width, print; |
| 83 | |
| 84 | src = dst = NULL; |
| 85 | if (vasprintf(&src, fmt, ap) <= 0) |
| 86 | goto fail; |
| 87 | |
| 88 | sz = strlen(src); |
| 89 | if ((dst = malloc(sz)) == NULL) |
| 90 | goto fail; |
| 91 | |
| 92 | if (maxsz > INT_MAX) |
| 93 | maxsz = INT_MAX; |
| 94 | |
| 95 | sp = src; |
| 96 | dp = dst; |
| 97 | ret = 0; |
| 98 | print = 1; |
| 99 | total_width = 0; |
| 100 | max_width = wp == NULL ? INT_MAX : *wp; |
| 101 | while (*sp != '\0') { |
| 102 | if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { |
| 103 | (void)mbtowc(NULL, NULL, MB_CUR_MAX); |
| 104 | if (dangerous_locale()) { |
| 105 | ret = -1; |
| 106 | break; |
| 107 | } |
| 108 | len = 1; |
| 109 | width = -1; |
| 110 | } else if (wp == NULL && |
| 111 | (wc == L'\n' || wc == L'\r' || wc == L'\t')) { |
| 112 | /* |
| 113 | * Don't use width uninitialized; the actual |
| 114 | * value doesn't matter because total_width |
| 115 | * is only returned for wp != NULL. |
| 116 | */ |
| 117 | width = 0; |
| 118 | } else if ((width = wcwidth(wc)) == -1 && |
| 119 | dangerous_locale()) { |
| 120 | ret = -1; |
| 121 | break; |
| 122 | } |
| 123 | |
| 124 | /* Valid, printable character. */ |
| 125 | |
| 126 | if (width >= 0) { |
| 127 | if (print && (dp - dst >= (int)maxsz - len || |
| 128 | total_width > max_width - width)) |
| 129 | print = 0; |
| 130 | if (print) { |
| 131 | total_width += width; |
| 132 | memcpy(dp, sp, len); |
| 133 | dp += len; |
| 134 | } |
| 135 | sp += len; |
| 136 | if (ret >= 0) |
| 137 | ret += len; |
| 138 | continue; |
| 139 | } |
| 140 | |
| 141 | /* Escaping required. */ |
| 142 | |
| 143 | while (len > 0) { |
| 144 | if (print && (dp - dst >= (int)maxsz - 4 || |
| 145 | total_width > max_width - 4)) |
| 146 | print = 0; |
| 147 | if (print) { |
| 148 | if (dp + 4 >= dst + sz) { |
| 149 | tsz = sz + 128; |
| 150 | if (tsz > maxsz) |
| 151 | tsz = maxsz; |
| 152 | tp = realloc(dst, tsz); |
| 153 | if (tp == NULL) { |
| 154 | ret = -1; |
| 155 | break; |
| 156 | } |
| 157 | dp = tp + (dp - dst); |
| 158 | dst = tp; |
| 159 | sz = tsz; |
| 160 | } |
| 161 | tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); |
| 162 | width = tp - dp; |
| 163 | total_width += width; |
| 164 | dp = tp; |
| 165 | } else |
| 166 | width = 4; |
| 167 | len--; |
| 168 | sp++; |
| 169 | if (ret >= 0) |
| 170 | ret += width; |
| 171 | } |
| 172 | if (len > 0) |
| 173 | break; |
| 174 | } |
| 175 | free(src); |
| 176 | *dp = '\0'; |
| 177 | *str = dst; |
| 178 | if (wp != NULL) |
| 179 | *wp = total_width; |
| 180 | |
| 181 | /* |
| 182 | * If the string was truncated by the width limit but |
| 183 | * would have fit into the size limit, the only sane way |
| 184 | * to report the problem is using the return value, such |
| 185 | * that the usual idiom "if (ret < 0 || ret >= sz) error" |
| 186 | * works as expected. |
| 187 | */ |
| 188 | |
| 189 | if (ret < (int)maxsz && !print) |
| 190 | ret = -1; |
| 191 | return ret; |
| 192 | |
| 193 | fail: |
| 194 | free(src); |
| 195 | free(dst); |
| 196 | *str = NULL; |
| 197 | if (wp != NULL) |
| 198 | *wp = 0; |
| 199 | return -1; |
| 200 | } |
| 201 | |
| 202 | int |
| 203 | snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) |
| 204 | { |
| 205 | va_list ap; |
| 206 | char *cp; |
| 207 | int ret; |
| 208 | |
| 209 | va_start(ap, fmt); |
| 210 | ret = vasnmprintf(&cp, sz, wp, fmt, ap); |
| 211 | va_end(ap); |
| 212 | (void)strlcpy(str, cp, sz); |
| 213 | free(cp); |
| 214 | return ret; |
| 215 | } |
| 216 | |
| 217 | /* |
| 218 | * To stay close to the standard interfaces, the following functions |
| 219 | * return the number of non-NUL bytes written. |
| 220 | */ |
| 221 | |
| 222 | int |
| 223 | vfmprintf(FILE *stream, const char *fmt, va_list ap) |
| 224 | { |
| 225 | char *str; |
| 226 | int ret; |
| 227 | |
| 228 | if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) |
| 229 | return -1; |
| 230 | if (fputs(str, stream) == EOF) |
| 231 | ret = -1; |
| 232 | free(str); |
| 233 | return ret; |
| 234 | } |
| 235 | |
| 236 | int |
| 237 | fmprintf(FILE *stream, const char *fmt, ...) |
| 238 | { |
| 239 | va_list ap; |
| 240 | int ret; |
| 241 | |
| 242 | va_start(ap, fmt); |
| 243 | ret = vfmprintf(stream, fmt, ap); |
| 244 | va_end(ap); |
| 245 | return ret; |
| 246 | } |
| 247 | |
| 248 | int |
| 249 | mprintf(const char *fmt, ...) |
| 250 | { |
| 251 | va_list ap; |
| 252 | int ret; |
| 253 | |
| 254 | va_start(ap, fmt); |
| 255 | ret = vfmprintf(stdout, fmt, ap); |
| 256 | va_end(ap); |
| 257 | return ret; |
| 258 | } |