Rev 3331 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2753 | jermar | 1 | /* |
| 2 | * Copyright (c) 2008 Jakub Jermar |
||
| 3 | * All rights reserved. |
||
| 4 | * |
||
| 5 | * Redistribution and use in source and binary forms, with or without |
||
| 6 | * modification, are permitted provided that the following conditions |
||
| 7 | * are met: |
||
| 8 | * |
||
| 9 | * - Redistributions of source code must retain the above copyright |
||
| 10 | * notice, this list of conditions and the following disclaimer. |
||
| 11 | * - Redistributions in binary form must reproduce the above copyright |
||
| 12 | * notice, this list of conditions and the following disclaimer in the |
||
| 13 | * documentation and/or other materials provided with the distribution. |
||
| 14 | * - The name of the author may not be used to endorse or promote products |
||
| 15 | * derived from this software without specific prior written permission. |
||
| 16 | * |
||
| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
||
| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
||
| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
||
| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
||
| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
||
| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
||
| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
||
| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
||
| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
||
| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||
| 27 | */ |
||
| 28 | |||
| 29 | /** @addtogroup libc |
||
| 30 | * @{ |
||
| 31 | */ |
||
| 32 | |||
| 33 | /** |
||
| 34 | * @file |
||
| 35 | * @brief |
||
| 36 | */ |
||
| 37 | |||
| 38 | #include <stdlib.h> |
||
| 39 | |||
| 40 | /** Token types used for tokenization of path. */ |
||
| 41 | typedef enum { |
||
| 42 | TK_INVALID, |
||
| 43 | TK_SLASH, |
||
| 44 | TK_DOT, |
||
| 45 | TK_DOTDOT, |
||
| 46 | TK_COMP, |
||
| 47 | TK_NUL |
||
| 48 | } tokval_t; |
||
| 49 | |||
| 50 | typedef struct { |
||
| 51 | tokval_t kind; |
||
| 52 | char *start; |
||
| 53 | char *stop; |
||
| 54 | } token_t; |
||
| 55 | |||
| 56 | /** Fake up the TK_SLASH token. */ |
||
| 57 | static token_t slash_token(char *start) |
||
| 58 | { |
||
| 59 | token_t ret; |
||
| 60 | ret.kind = TK_SLASH; |
||
| 61 | ret.start = start; |
||
| 62 | ret.stop = start; |
||
| 63 | return ret; |
||
| 64 | } |
||
| 65 | |||
| 66 | /** Given a token, return the next token. */ |
||
| 67 | static token_t next_token(token_t *cur) |
||
| 68 | { |
||
| 69 | token_t ret; |
||
| 70 | |||
| 71 | if (cur->stop[1] == '\0') { |
||
| 72 | ret.kind = TK_NUL; |
||
| 73 | ret.start = cur->stop + 1; |
||
| 74 | ret.stop = ret.start; |
||
| 75 | return ret; |
||
| 76 | } |
||
| 77 | if (cur->stop[1] == '/') { |
||
| 78 | ret.kind = TK_SLASH; |
||
| 79 | ret.start = cur->stop + 1; |
||
| 80 | ret.stop = ret.start; |
||
| 81 | return ret; |
||
| 82 | } |
||
| 83 | if (cur->stop[1] == '.' && (!cur->stop[2] || cur->stop[2] == '/')) { |
||
| 84 | ret.kind = TK_DOT; |
||
| 85 | ret.start = cur->stop + 1; |
||
| 86 | ret.stop = ret.start; |
||
| 87 | return ret; |
||
| 88 | } |
||
| 89 | if (cur->stop[1] == '.' && cur->stop[2] == '.' && |
||
| 90 | (!cur->stop[3] || cur->stop[3] == '/')) { |
||
| 91 | ret.kind = TK_DOTDOT; |
||
| 92 | ret.start = cur->stop + 1; |
||
| 93 | ret.stop = cur->stop + 2; |
||
| 94 | return ret; |
||
| 95 | } |
||
| 96 | unsigned i; |
||
| 97 | for (i = 1; cur->stop[i] && cur->stop[i] != '/'; i++) |
||
| 98 | ; |
||
| 99 | ret.kind = TK_COMP; |
||
| 100 | ret.start = &cur->stop[1]; |
||
| 101 | ret.stop = &cur->stop[i - 1]; |
||
| 102 | return ret; |
||
| 103 | } |
||
| 104 | |||
| 105 | /** States used by canonify(). */ |
||
| 106 | typedef enum { |
||
| 107 | S_INI, |
||
| 108 | S_A, |
||
| 109 | S_B, |
||
| 110 | S_C, |
||
| 111 | S_ACCEPT, |
||
| 112 | S_RESTART, |
||
| 113 | S_REJECT |
||
| 114 | } state_t; |
||
| 115 | |||
| 116 | typedef struct { |
||
| 117 | state_t s; |
||
| 118 | void (* f)(token_t *, token_t *, token_t *); |
||
| 119 | } change_state_t; |
||
| 120 | |||
| 121 | /* |
||
| 122 | * Actions that can be performed when transitioning from one |
||
| 123 | * state of canonify() to another. |
||
| 124 | */ |
||
| 125 | static void set_first_slash(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 126 | { |
||
| 127 | *tfsl = *t; |
||
| 3331 | jermar | 128 | *tlcomp = *t; |
| 2753 | jermar | 129 | } |
| 130 | static void save_component(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 131 | { |
||
| 132 | *tlcomp = *t; |
||
| 133 | } |
||
| 134 | static void terminate_slash(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 135 | { |
||
| 136 | if (tfsl->stop[1]) /* avoid writing to a well-formatted path */ |
||
| 137 | tfsl->stop[1] = '\0'; |
||
| 138 | } |
||
| 139 | static void remove_trailing_slash(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 140 | { |
||
| 141 | t->start[-1] = '\0'; |
||
| 142 | } |
||
| 143 | /** Eat the extra '/'.. |
||
| 144 | * |
||
| 145 | * @param t The current TK_SLASH token. |
||
| 146 | */ |
||
| 147 | static void shift_slash(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 148 | { |
||
| 149 | char *p = t->start; |
||
| 150 | char *q = t->stop + 1; |
||
| 151 | while ((*p++ = *q++)) |
||
| 152 | ; |
||
| 153 | } |
||
| 154 | /** Eat the extra '.'. |
||
| 155 | * |
||
| 156 | * @param t The current TK_DOT token. |
||
| 157 | */ |
||
| 158 | static void shift_dot(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 159 | { |
||
| 160 | char *p = t->start; |
||
| 161 | char *q = t->stop + 1; |
||
| 162 | while ((*p++ = *q++)) |
||
| 163 | ; |
||
| 164 | } |
||
| 165 | /** Collapse the TK_COMP TK_SLASH TK_DOTDOT pattern. |
||
| 166 | * |
||
| 167 | * @param t The current TK_DOTDOT token. |
||
| 168 | * @param tlcomp The last TK_COMP token. |
||
| 169 | */ |
||
| 170 | static void shift_dotdot(token_t *t, token_t *tfsl, token_t *tlcomp) |
||
| 171 | { |
||
| 172 | char *p = tlcomp->start; |
||
| 173 | char *q = t->stop + 1; |
||
| 174 | while ((*p++ = *q++)) |
||
| 175 | ; |
||
| 176 | } |
||
| 177 | |||
| 178 | /** Transition function for canonify(). */ |
||
| 179 | static change_state_t trans[4][6] = { |
||
| 180 | [S_INI] = { |
||
| 181 | [TK_SLASH] = { |
||
| 182 | .s = S_A, |
||
| 183 | .f = set_first_slash, |
||
| 184 | }, |
||
| 185 | [TK_DOT] = { |
||
| 186 | .s = S_REJECT, |
||
| 187 | .f = NULL, |
||
| 188 | }, |
||
| 189 | [TK_DOTDOT] = { |
||
| 190 | .s = S_REJECT, |
||
| 191 | .f = NULL, |
||
| 192 | }, |
||
| 193 | [TK_COMP] = { |
||
| 194 | .s = S_REJECT, |
||
| 195 | .f = NULL, |
||
| 196 | }, |
||
| 197 | [TK_NUL] = { |
||
| 198 | .s = S_REJECT, |
||
| 199 | .f = NULL, |
||
| 200 | }, |
||
| 201 | [TK_INVALID] = { |
||
| 202 | .s = S_REJECT, |
||
| 203 | .f = NULL, |
||
| 204 | }, |
||
| 205 | }, |
||
| 206 | [S_A] = { |
||
| 207 | [TK_SLASH] = { |
||
| 208 | .s = S_A, |
||
| 209 | .f = set_first_slash, |
||
| 210 | }, |
||
| 211 | [TK_DOT] = { |
||
| 212 | .s = S_A, |
||
| 213 | .f = NULL, |
||
| 214 | }, |
||
| 215 | [TK_DOTDOT] = { |
||
| 216 | .s = S_A, |
||
| 217 | .f = NULL, |
||
| 218 | }, |
||
| 219 | [TK_COMP] = { |
||
| 220 | .s = S_B, |
||
| 221 | .f = save_component, |
||
| 222 | }, |
||
| 223 | [TK_NUL] = { |
||
| 224 | .s = S_ACCEPT, |
||
| 225 | .f = terminate_slash, |
||
| 226 | }, |
||
| 227 | [TK_INVALID] = { |
||
| 228 | .s = S_REJECT, |
||
| 229 | .f = NULL, |
||
| 230 | }, |
||
| 231 | }, |
||
| 232 | [S_B] = { |
||
| 233 | [TK_SLASH] = { |
||
| 234 | .s = S_C, |
||
| 235 | .f = NULL, |
||
| 236 | }, |
||
| 237 | [TK_DOT] = { |
||
| 238 | .s = S_REJECT, |
||
| 239 | .f = NULL, |
||
| 240 | }, |
||
| 241 | [TK_DOTDOT] = { |
||
| 242 | .s = S_REJECT, |
||
| 243 | .f = NULL, |
||
| 244 | }, |
||
| 245 | [TK_COMP] = { |
||
| 246 | .s = S_REJECT, |
||
| 247 | .f = NULL, |
||
| 248 | }, |
||
| 249 | [TK_NUL] = { |
||
| 250 | .s = S_ACCEPT, |
||
| 251 | .f = NULL, |
||
| 252 | }, |
||
| 253 | [TK_INVALID] = { |
||
| 254 | .s = S_REJECT, |
||
| 255 | .f = NULL, |
||
| 256 | }, |
||
| 257 | }, |
||
| 258 | [S_C] = { |
||
| 259 | [TK_SLASH] = { |
||
| 260 | .s = S_RESTART, |
||
| 261 | .f = shift_slash, |
||
| 262 | }, |
||
| 263 | [TK_DOT] = { |
||
| 264 | .s = S_RESTART, |
||
| 265 | .f = shift_dot, |
||
| 266 | }, |
||
| 267 | [TK_DOTDOT] = { |
||
| 268 | .s = S_RESTART, |
||
| 269 | .f = shift_dotdot, |
||
| 270 | }, |
||
| 271 | [TK_COMP] = { |
||
| 272 | .s = S_B, |
||
| 273 | .f = save_component, |
||
| 274 | }, |
||
| 275 | [TK_NUL] = { |
||
| 276 | .s = S_ACCEPT, |
||
| 277 | .f = remove_trailing_slash, |
||
| 278 | }, |
||
| 279 | [TK_INVALID] = { |
||
| 280 | .s = S_REJECT, |
||
| 281 | .f = NULL, |
||
| 282 | }, |
||
| 283 | } |
||
| 284 | }; |
||
| 285 | |||
| 286 | /** Canonify a file system path. |
||
| 287 | * |
||
| 288 | * A file system path is canonical, if the following holds: |
||
| 289 | * 1) the path is absolute (i.e. a/b/c is not canonical) |
||
| 290 | * 2) there is no trailing slash in the path (i.e. /a/b/c is not canonical) |
||
| 291 | * 3) there is no extra slash in the path (i.e. /a//b/c is not canonical) |
||
| 292 | * 4) there is no '.' component in the path (i.e. /a/./b/c is not canonical) |
||
| 293 | * 5) there is no '..' component in the path (i.e. /a/b/../c is not canonical) |
||
| 294 | * |
||
| 295 | * This function makes a potentially non-canonical file system path canonical. |
||
| 296 | * It works in-place and requires a NULL-terminated input string. |
||
| 297 | * |
||
| 298 | * @param path Path to be canonified. |
||
| 299 | * @param lenp Pointer where the length of the final path will be |
||
| 300 | * stored. Can be NULL. |
||
| 301 | * |
||
| 302 | * @return Canonified path or NULL on failure. |
||
| 303 | */ |
||
| 304 | char *canonify(char *path, size_t *lenp) |
||
| 305 | { |
||
| 306 | state_t state; |
||
| 307 | token_t t; |
||
| 308 | token_t tfsl; /* first slash */ |
||
| 309 | token_t tlcomp; /* last component */ |
||
| 310 | if (*path != '/') |
||
| 311 | return NULL; |
||
| 312 | tfsl = slash_token(path); |
||
| 313 | restart: |
||
| 314 | state = S_INI; |
||
| 315 | t = tfsl; |
||
| 316 | tlcomp = tfsl; |
||
| 317 | while (state != S_ACCEPT && state != S_RESTART && state != S_REJECT) { |
||
| 318 | if (trans[state][t.kind].f) |
||
| 319 | trans[state][t.kind].f(&t, &tfsl, &tlcomp); |
||
| 320 | state = trans[state][t.kind].s; |
||
| 321 | t = next_token(&t); |
||
| 322 | } |
||
| 323 | |||
| 324 | switch (state) { |
||
| 325 | case S_RESTART: |
||
| 326 | goto restart; |
||
| 327 | case S_REJECT: |
||
| 328 | return NULL; |
||
| 329 | case S_ACCEPT: |
||
| 330 | if (lenp) |
||
| 331 | *lenp = (size_t)((tlcomp.stop - tfsl.start) + 1); |
||
| 332 | return tfsl.start; |
||
| 333 | default: |
||
| 334 | abort(); |
||
| 335 | } |
||
| 336 | } |
||
| 337 | |||
| 338 | /** |
||
| 339 | * @} |
||
| 340 | */ |