| 1 | /* Return the canonical absolute name of a given file. |
| 2 | Copyright (C) 1996-2009 Free Software Foundation, Inc. |
| 3 | This file is part of the GNU C Library. |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU Lesser General Public License as published by |
| 7 | the Free Software Foundation; either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU Lesser General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU Lesser General Public License |
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | #ifndef _LIBC |
| 19 | # include <config.h> |
| 20 | #endif |
| 21 | |
| 22 | #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC |
| 23 | |
| 24 | /* Specification. */ |
| 25 | #include <stdlib.h> |
| 26 | |
| 27 | #include <alloca.h> |
| 28 | #include <string.h> |
| 29 | #include <unistd.h> |
| 30 | #include <limits.h> |
| 31 | #if HAVE_SYS_PARAM_H || defined _LIBC |
| 32 | # include <sys/param.h> |
| 33 | #endif |
| 34 | #include <sys/stat.h> |
| 35 | #include <errno.h> |
| 36 | #include <stddef.h> |
| 37 | |
| 38 | #ifdef _LIBC |
| 39 | # include <shlib-compat.h> |
| 40 | #else |
| 41 | # define SHLIB_COMPAT(lib, introduced, obsoleted) 0 |
| 42 | # define versioned_symbol(lib, local, symbol, version) |
| 43 | # define compat_symbol(lib, local, symbol, version) |
| 44 | # define weak_alias(local, symbol) |
| 45 | # define __canonicalize_file_name canonicalize_file_name |
| 46 | # define __realpath realpath |
| 47 | # include "pathmax.h" |
| 48 | # include "malloca.h" |
| 49 | # if HAVE_GETCWD |
| 50 | # ifdef VMS |
| 51 | /* We want the directory in Unix syntax, not in VMS syntax. */ |
| 52 | # define __getcwd(buf, max) getcwd (buf, max, 0) |
| 53 | # else |
| 54 | # define __getcwd getcwd |
| 55 | # endif |
| 56 | # else |
| 57 | # define __getcwd(buf, max) getwd (buf) |
| 58 | # endif |
| 59 | # define __readlink readlink |
| 60 | # define __set_errno(e) errno = (e) |
| 61 | # ifndef MAXSYMLINKS |
| 62 | # ifdef SYMLOOP_MAX |
| 63 | # define MAXSYMLINKS SYMLOOP_MAX |
| 64 | # else |
| 65 | # define MAXSYMLINKS 20 |
| 66 | # endif |
| 67 | # endif |
| 68 | #endif |
| 69 | |
| 70 | #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT |
| 71 | # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0 |
| 72 | #endif |
| 73 | |
| 74 | #if !FUNC_REALPATH_WORKS || defined _LIBC |
| 75 | /* Return the canonical absolute name of file NAME. A canonical name |
| 76 | does not contain any `.', `..' components nor any repeated path |
| 77 | separators ('/') or symlinks. All path components must exist. If |
| 78 | RESOLVED is null, the result is malloc'd; otherwise, if the |
| 79 | canonical name is PATH_MAX chars or more, returns null with `errno' |
| 80 | set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, |
| 81 | returns the name in RESOLVED. If the name cannot be resolved and |
| 82 | RESOLVED is non-NULL, it contains the path of the first component |
| 83 | that cannot be resolved. If the path can be resolved, RESOLVED |
| 84 | holds the same value as the value returned. */ |
| 85 | |
| 86 | char * |
| 87 | __realpath (const char *name, char *resolved) |
| 88 | { |
| 89 | char *rpath, *dest, *extra_buf = NULL; |
| 90 | const char *start, *end, *rpath_limit; |
| 91 | long int path_max; |
| 92 | int num_links = 0; |
| 93 | |
| 94 | if (name == NULL) |
| 95 | { |
| 96 | /* As per Single Unix Specification V2 we must return an error if |
| 97 | either parameter is a null pointer. We extend this to allow |
| 98 | the RESOLVED parameter to be NULL in case the we are expected to |
| 99 | allocate the room for the return value. */ |
| 100 | __set_errno (EINVAL); |
| 101 | return NULL; |
| 102 | } |
| 103 | |
| 104 | if (name[0] == '\0') |
| 105 | { |
| 106 | /* As per Single Unix Specification V2 we must return an error if |
| 107 | the name argument points to an empty string. */ |
| 108 | __set_errno (ENOENT); |
| 109 | return NULL; |
| 110 | } |
| 111 | |
| 112 | #ifdef PATH_MAX |
| 113 | path_max = PATH_MAX; |
| 114 | #else |
| 115 | path_max = pathconf (name, _PC_PATH_MAX); |
| 116 | if (path_max <= 0) |
| 117 | path_max = 1024; |
| 118 | #endif |
| 119 | |
| 120 | if (resolved == NULL) |
| 121 | { |
| 122 | rpath = malloc (path_max); |
| 123 | if (rpath == NULL) |
| 124 | { |
| 125 | /* It's easier to set errno to ENOMEM than to rely on the |
| 126 | 'malloc-posix' gnulib module. */ |
| 127 | errno = ENOMEM; |
| 128 | return NULL; |
| 129 | } |
| 130 | } |
| 131 | else |
| 132 | rpath = resolved; |
| 133 | rpath_limit = rpath + path_max; |
| 134 | |
| 135 | if (name[0] != '/') |
| 136 | { |
| 137 | if (!__getcwd (rpath, path_max)) |
| 138 | { |
| 139 | rpath[0] = '\0'; |
| 140 | goto error; |
| 141 | } |
| 142 | dest = strchr (rpath, '\0'); |
| 143 | } |
| 144 | else |
| 145 | { |
| 146 | rpath[0] = '/'; |
| 147 | dest = rpath + 1; |
| 148 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && name[1] == '/') |
| 149 | *dest++ = '/'; |
| 150 | } |
| 151 | |
| 152 | for (start = end = name; *start; start = end) |
| 153 | { |
| 154 | #ifdef _LIBC |
| 155 | struct stat64 st; |
| 156 | #else |
| 157 | struct stat st; |
| 158 | #endif |
| 159 | int n; |
| 160 | |
| 161 | /* Skip sequence of multiple path-separators. */ |
| 162 | while (*start == '/') |
| 163 | ++start; |
| 164 | |
| 165 | /* Find end of path component. */ |
| 166 | for (end = start; *end && *end != '/'; ++end) |
| 167 | /* Nothing. */; |
| 168 | |
| 169 | if (end - start == 0) |
| 170 | break; |
| 171 | else if (end - start == 1 && start[0] == '.') |
| 172 | /* nothing */; |
| 173 | else if (end - start == 2 && start[0] == '.' && start[1] == '.') |
| 174 | { |
| 175 | /* Back up to previous component, ignore if at root already. */ |
| 176 | if (dest > rpath + 1) |
| 177 | while ((--dest)[-1] != '/'); |
| 178 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 |
| 179 | && *dest == '/') |
| 180 | dest++; |
| 181 | } |
| 182 | else |
| 183 | { |
| 184 | size_t new_size; |
| 185 | |
| 186 | if (dest[-1] != '/') |
| 187 | *dest++ = '/'; |
| 188 | |
| 189 | if (dest + (end - start) >= rpath_limit) |
| 190 | { |
| 191 | ptrdiff_t dest_offset = dest - rpath; |
| 192 | char *new_rpath; |
| 193 | |
| 194 | if (resolved) |
| 195 | { |
| 196 | __set_errno (ENAMETOOLONG); |
| 197 | if (dest > rpath + 1) |
| 198 | dest--; |
| 199 | *dest = '\0'; |
| 200 | goto error; |
| 201 | } |
| 202 | new_size = rpath_limit - rpath; |
| 203 | if (end - start + 1 > path_max) |
| 204 | new_size += end - start + 1; |
| 205 | else |
| 206 | new_size += path_max; |
| 207 | new_rpath = (char *) realloc (rpath, new_size); |
| 208 | if (new_rpath == NULL) |
| 209 | { |
| 210 | /* It's easier to set errno to ENOMEM than to rely on the |
| 211 | 'realloc-posix' gnulib module. */ |
| 212 | errno = ENOMEM; |
| 213 | goto error; |
| 214 | } |
| 215 | rpath = new_rpath; |
| 216 | rpath_limit = rpath + new_size; |
| 217 | |
| 218 | dest = rpath + dest_offset; |
| 219 | } |
| 220 | |
| 221 | #ifdef _LIBC |
| 222 | dest = __mempcpy (dest, start, end - start); |
| 223 | #else |
| 224 | memcpy (dest, start, end - start); |
| 225 | dest += end - start; |
| 226 | #endif |
| 227 | *dest = '\0'; |
| 228 | |
| 229 | #ifdef _LIBC |
| 230 | if (__lxstat64 (_STAT_VER, rpath, &st) < 0) |
| 231 | #else |
| 232 | if (lstat (rpath, &st) < 0) |
| 233 | #endif |
| 234 | goto error; |
| 235 | |
| 236 | if (S_ISLNK (st.st_mode)) |
| 237 | { |
| 238 | char *buf; |
| 239 | size_t len; |
| 240 | |
| 241 | if (++num_links > MAXSYMLINKS) |
| 242 | { |
| 243 | __set_errno (ELOOP); |
| 244 | goto error; |
| 245 | } |
| 246 | |
| 247 | buf = malloca (path_max); |
| 248 | if (!buf) |
| 249 | { |
| 250 | errno = ENOMEM; |
| 251 | goto error; |
| 252 | } |
| 253 | |
| 254 | n = __readlink (rpath, buf, path_max - 1); |
| 255 | if (n < 0) |
| 256 | { |
| 257 | int saved_errno = errno; |
| 258 | freea (buf); |
| 259 | errno = saved_errno; |
| 260 | goto error; |
| 261 | } |
| 262 | buf[n] = '\0'; |
| 263 | |
| 264 | if (!extra_buf) |
| 265 | { |
| 266 | extra_buf = malloca (path_max); |
| 267 | if (!extra_buf) |
| 268 | { |
| 269 | freea (buf); |
| 270 | errno = ENOMEM; |
| 271 | goto error; |
| 272 | } |
| 273 | } |
| 274 | |
| 275 | len = strlen (end); |
| 276 | if ((long int) (n + len) >= path_max) |
| 277 | { |
| 278 | freea (buf); |
| 279 | __set_errno (ENAMETOOLONG); |
| 280 | goto error; |
| 281 | } |
| 282 | |
| 283 | /* Careful here, end may be a pointer into extra_buf... */ |
| 284 | memmove (&extra_buf[n], end, len + 1); |
| 285 | name = end = memcpy (extra_buf, buf, n); |
| 286 | |
| 287 | if (buf[0] == '/') |
| 288 | { |
| 289 | dest = rpath + 1; /* It's an absolute symlink */ |
| 290 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && buf[1] == '/') |
| 291 | *dest++ = '/'; |
| 292 | } |
| 293 | else |
| 294 | { |
| 295 | /* Back up to previous component, ignore if at root |
| 296 | already: */ |
| 297 | if (dest > rpath + 1) |
| 298 | while ((--dest)[-1] != '/'); |
| 299 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 |
| 300 | && *dest == '/') |
| 301 | dest++; |
| 302 | } |
| 303 | } |
| 304 | else if (!S_ISDIR (st.st_mode) && *end != '\0') |
| 305 | { |
| 306 | __set_errno (ENOTDIR); |
| 307 | goto error; |
| 308 | } |
| 309 | } |
| 310 | } |
| 311 | if (dest > rpath + 1 && dest[-1] == '/') |
| 312 | --dest; |
| 313 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && *dest == '/') |
| 314 | dest++; |
| 315 | *dest = '\0'; |
| 316 | |
| 317 | if (extra_buf) |
| 318 | freea (extra_buf); |
| 319 | |
| 320 | return rpath; |
| 321 | |
| 322 | error: |
| 323 | { |
| 324 | int saved_errno = errno; |
| 325 | if (extra_buf) |
| 326 | freea (extra_buf); |
| 327 | if (resolved == NULL) |
| 328 | free (rpath); |
| 329 | errno = saved_errno; |
| 330 | } |
| 331 | return NULL; |
| 332 | } |
| 333 | versioned_symbol (libc, __realpath, realpath, GLIBC_2_3); |
| 334 | #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */ |
| 335 | |
| 336 | |
| 337 | #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3) |
| 338 | char * |
| 339 | attribute_compat_text_section |
| 340 | __old_realpath (const char *name, char *resolved) |
| 341 | { |
| 342 | if (resolved == NULL) |
| 343 | { |
| 344 | __set_errno (EINVAL); |
| 345 | return NULL; |
| 346 | } |
| 347 | |
| 348 | return __realpath (name, resolved); |
| 349 | } |
| 350 | compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0); |
| 351 | #endif |
| 352 | |
| 353 | |
| 354 | char * |
| 355 | __canonicalize_file_name (const char *name) |
| 356 | { |
| 357 | return __realpath (name, NULL); |
| 358 | } |
| 359 | weak_alias (__canonicalize_file_name, canonicalize_file_name) |
| 360 | |
| 361 | #else |
| 362 | |
| 363 | /* This declaration is solely to ensure that after preprocessing |
| 364 | this file is never empty. */ |
| 365 | typedef int dummy; |
| 366 | |
| 367 | #endif |