external/gpl2/xcvs/dist/lib/getcwd.c

   1 /* Copyright (C) 1991,92,93,94,95,96,97,98,99,2004,2005 Free Software
   2    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 General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    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 General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #ifdef  HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #if !_LIBC
  24 # include "getcwd.h"
  25 #endif
  26
  27 #include <errno.h>
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <stdbool.h>
  31 #include <stddef.h>
  32
  33 #include <fcntl.h> /* For AT_FDCWD on Solaris 9.  */
  34
  35 #ifndef __set_errno
  36 # define __set_errno(val) (errno = (val))
  37 #endif
  38
  39 #if HAVE_DIRENT_H || _LIBC
  40 # include <dirent.h>
  41 # ifndef _D_EXACT_NAMLEN
  42 #  define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
  43 # endif
  44 #else
  45 # define dirent direct
  46 # if HAVE_SYS_NDIR_H
  47 #  include <sys/ndir.h>
  48 # endif
  49 # if HAVE_SYS_DIR_H
  50 #  include <sys/dir.h>
  51 # endif
  52 # if HAVE_NDIR_H
  53 #  include <ndir.h>
  54 # endif
  55 #endif
  56 #ifndef _D_EXACT_NAMLEN
  57 # define _D_EXACT_NAMLEN(d) ((d)->d_namlen)
  58 #endif
  59 #ifndef _D_ALLOC_NAMLEN
  60 # define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
  61 #endif
  62
  63 #if HAVE_UNISTD_H || _LIBC
  64 # include <unistd.h>
  65 #endif
  66
  67 #include <stdlib.h>
  68 #include <string.h>
  69
  70 #if _LIBC
  71 # ifndef mempcpy
  72 #  define mempcpy __mempcpy
  73 # endif
  74 #else
  75 # include "mempcpy.h"
  76 #endif
  77
  78 #include <limits.h>
  79
  80 #ifdef ENAMETOOLONG
  81 # define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
  82 #else
  83 # define is_ENAMETOOLONG(x) 0
  84 #endif
  85
  86 #ifndef MAX
  87 # define MAX(a, b) ((a) < (b) ? (b) : (a))
  88 #endif
  89 #ifndef MIN
  90 # define MIN(a, b) ((a) < (b) ? (a) : (b))
  91 #endif
  92
  93 #ifndef PATH_MAX
  94 # ifdef MAXPATHLEN
  95 #  define PATH_MAX MAXPATHLEN
  96 # else
  97 #  define PATH_MAX 1024
  98 # endif
  99 #endif
 100
 101 #if D_INO_IN_DIRENT
 102 # define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
 103 #else
 104 # define MATCHING_INO(dp, ino) true
 105 #endif
 106
 107 #if !_LIBC
 108 # define __getcwd getcwd
 109 # define __lstat lstat
 110 # define __closedir closedir
 111 # define __opendir opendir
 112 # define __readdir readdir
 113 #endif
 114 \f
 115 /* Get the name of the current working directory, and put it in SIZE
 116    bytes of BUF.  Returns NULL if the directory couldn't be determined or
 117    SIZE was too small.  If successful, returns BUF.  In GNU, if BUF is
 118    NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
 119    unless SIZE == 0, in which case it is as big as necessary.  */
 120
 121 char *
 122 __getcwd (char *buf, size_t size)
 123 {
 124   /* Lengths of big file name components and entire file names, and a
 125      deep level of file name nesting.  These numbers are not upper
 126      bounds; they are merely large values suitable for initial
 127      allocations, designed to be large enough for most real-world
 128      uses.  */
 129   enum
 130     {
 131       BIG_FILE_NAME_COMPONENT_LENGTH = 255,
 132       BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
 133       DEEP_NESTING = 100
 134     };
 135
 136 #ifdef AT_FDCWD
 137   int fd = AT_FDCWD;
 138   bool fd_needs_closing = false;
 139 #else
 140   char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
 141   char *dotlist = dots;
 142   size_t dotsize = sizeof dots;
 143   size_t dotlen = 0;
 144 #endif
 145   DIR *dirstream = NULL;
 146   dev_t rootdev, thisdev;
 147   ino_t rootino, thisino;
 148   char *dir;
 149   register char *dirp;
 150   struct stat st;
 151   size_t allocated = size;
 152   size_t used;
 153
 154 #if HAVE_PARTLY_WORKING_GETCWD && !defined AT_FDCWD
 155   /* The system getcwd works, except it sometimes fails when it
 156      shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.  If
 157      AT_FDCWD is not defined, the algorithm below is O(N**2) and this
 158      is much slower than the system getcwd (at least on GNU/Linux).
 159      So trust the system getcwd's results unless they look
 160      suspicious.  */
 161 # undef getcwd
 162   dir = getcwd (buf, size);
 163   if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
 164     return dir;
 165 #endif
 166
 167   if (size == 0)
 168     {
 169       if (buf != NULL)
 170         {
 171           __set_errno (EINVAL);
 172           return NULL;
 173         }
 174
 175       allocated = BIG_FILE_NAME_LENGTH + 1;
 176     }
 177
 178   if (buf == NULL)
 179     {
 180       dir = malloc (allocated);
 181       if (dir == NULL)
 182         return NULL;
 183     }
 184   else
 185     dir = buf;
 186
 187   dirp = dir + allocated;
 188   *--dirp = '\0';
 189
 190   if (__lstat (".", &st) < 0)
 191     goto lose;
 192   thisdev = st.st_dev;
 193   thisino = st.st_ino;
 194
 195   if (__lstat ("/", &st) < 0)
 196     goto lose;
 197   rootdev = st.st_dev;
 198   rootino = st.st_ino;
 199
 200   while (!(thisdev == rootdev && thisino == rootino))
 201     {
 202       struct dirent *d;
 203       dev_t dotdev;
 204       ino_t dotino;
 205       bool mount_point;
 206       int parent_status;
 207
 208       /* Look at the parent directory.  */
 209 #ifdef AT_FDCWD
 210       fd = openat (fd, "..", O_RDONLY);
 211       if (fd < 0)
 212         goto lose;
 213       fd_needs_closing = true;
 214       parent_status = fstat (fd, &st);
 215 #else
 216       dotlist[dotlen++] = '.';
 217       dotlist[dotlen++] = '.';
 218       dotlist[dotlen] = '\0';
 219       parent_status = __lstat (dotlist, &st);
 220 #endif
 221       if (parent_status != 0)
 222         goto lose;
 223
 224       if (dirstream && __closedir (dirstream) != 0)
 225         {
 226           dirstream = NULL;
 227           goto lose;
 228         }
 229
 230       /* Figure out if this directory is a mount point.  */
 231       dotdev = st.st_dev;
 232       dotino = st.st_ino;
 233       mount_point = dotdev != thisdev;
 234
 235       /* Search for the last directory.  */
 236 #ifdef AT_FDCWD
 237       dirstream = fdopendir (fd);
 238       if (dirstream == NULL)
 239         goto lose;
 240       fd_needs_closing = false;
 241 #else
 242       dirstream = __opendir (dotlist);
 243       if (dirstream == NULL)
 244         goto lose;
 245       dotlist[dotlen++] = '/';
 246 #endif
 247       /* Clear errno to distinguish EOF from error if readdir returns
 248          NULL.  */
 249       __set_errno (0);
 250       while ((d = __readdir (dirstream)) != NULL)
 251         {
 252           if (d->d_name[0] == '.' &&
 253               (d->d_name[1] == '\0' ||
 254                (d->d_name[1] == '.' && d->d_name[2] == '\0')))
 255             continue;
 256           if (MATCHING_INO (d, thisino) || mount_point)
 257             {
 258               int entry_status;
 259 #ifdef AT_FDCWD
 260               entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
 261 #else
 262               /* Compute size needed for this file name, or for the file
 263                  name ".." in the same directory, whichever is larger.
 264                  Room for ".." might be needed the next time through
 265                  the outer loop.  */
 266               size_t name_alloc = _D_ALLOC_NAMLEN (d);
 267               size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
 268
 269               if (filesize < dotlen)
 270                 goto memory_exhausted;
 271
 272               if (dotsize < filesize)
 273                 {
 274                   /* My, what a deep directory tree you have, Grandma.  */
 275                   size_t newsize = MAX (filesize, dotsize * 2);
 276                   size_t i;
 277                   if (newsize < dotsize)
 278                     goto memory_exhausted;
 279                   if (dotlist != dots)
 280                     free (dotlist);
 281                   dotlist = malloc (newsize);
 282                   if (dotlist == NULL)
 283                     goto lose;
 284                   dotsize = newsize;
 285
 286                   i = 0;
 287                   do
 288                     {
 289                       dotlist[i++] = '.';
 290                       dotlist[i++] = '.';
 291                       dotlist[i++] = '/';
 292                     }
 293                   while (i < dotlen);
 294                 }
 295
 296               strcpy (dotlist + dotlen, d->d_name);
 297               entry_status = __lstat (dotlist, &st);
 298 #endif
 299               /* We don't fail here if we cannot stat() a directory entry.
 300                  This can happen when (network) file systems fail.  If this
 301                  entry is in fact the one we are looking for we will find
 302                  out soon as we reach the end of the directory without
 303                  having found anything.  */
 304               if (entry_status == 0 && S_ISDIR (st.st_mode)
 305                   && st.st_dev == thisdev && st.st_ino == thisino)
 306                 break;
 307             }
 308         }
 309       if (d == NULL)
 310         {
 311           if (errno == 0)
 312             /* EOF on dirstream, which means that the current directory
 313                has been removed.  */
 314             __set_errno (ENOENT);
 315           goto lose;
 316         }
 317       else
 318         {
 319           size_t dirroom = dirp - dir;
 320           size_t namlen = _D_EXACT_NAMLEN (d);
 321
 322           if (dirroom <= namlen)
 323             {
 324               if (size != 0)
 325                 {
 326                   __set_errno (ERANGE);
 327                   goto lose;
 328                 }
 329               else
 330                 {
 331                   char *tmp;
 332                   size_t oldsize = allocated;
 333
 334                   allocated += MAX (allocated, namlen);
 335                   if (allocated < oldsize
 336                       || ! (tmp = realloc (dir, allocated)))
 337                     goto memory_exhausted;
 338
 339                   /* Move current contents up to the end of the buffer.
 340                      This is guaranteed to be non-overlapping.  */
 341                   dirp = memcpy (tmp + allocated - (oldsize - dirroom),
 342                                  tmp + dirroom,
 343                                  oldsize - dirroom);
 344                   dir = tmp;
 345                 }
 346             }
 347           dirp -= namlen;
 348           memcpy (dirp, d->d_name, namlen);
 349           *--dirp = '/';
 350         }
 351
 352       thisdev = dotdev;
 353       thisino = dotino;
 354     }
 355
 356   if (dirstream && __closedir (dirstream) != 0)
 357     {
 358       dirstream = NULL;
 359       goto lose;
 360     }
 361
 362   if (dirp == &dir[allocated - 1])
 363     *--dirp = '/';
 364
 365 #ifndef AT_FDCWD
 366   if (dotlist != dots)
 367     free (dotlist);
 368 #endif
 369
 370   used = dir + allocated - dirp;
 371   memmove (dir, dirp, used);
 372
 373   if (buf == NULL && size == 0)
 374     /* Ensure that the buffer is only as large as necessary.  */
 375     buf = realloc (dir, used);
 376
 377   if (buf == NULL)
 378     /* Either buf was NULL all along, or `realloc' failed but
 379        we still have the original string.  */
 380     buf = dir;
 381
 382   return buf;
 383
 384  memory_exhausted:
 385   __set_errno (ENOMEM);
 386  lose:
 387   {
 388     int save = errno;
 389     if (dirstream)
 390       __closedir (dirstream);
 391 #ifdef AT_FDCWD
 392     if (fd_needs_closing)
 393       close (fd);
 394 #else
 395     if (dotlist != dots)
 396       free (dotlist);
 397 #endif
 398     if (buf == NULL)
 399       free (dir);
 400     __set_errno (save);
 401   }
 402   return NULL;
 403 }
 404
 405 #ifdef weak_alias
 406 weak_alias (__getcwd, getcwd)
 407 #endif