toolchain/gcc/newlib/libc/unix/getcwd.c

   1 /*
   2  * Copyright (c) 1989, 1991 The Regents of the University of California.
   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  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)getcwd.c    5.11 (Berkeley) 2/24/91";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/stat.h>
  39 #include <errno.h>
  40 #include <dirent.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45 #include <reent.h>
  46 #include <_syslist.h>
  47
  48 #define bcopy(a,b,c)    memmove (b,a,c)
  49
  50 #define ISDOT(dp) \
  51         (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
  52            (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
  53
  54 #ifndef _REENT_ONLY
  55
  56 char *
  57 getcwd (pt, size)
  58      char *pt;
  59      size_t size;
  60 {
  61   register struct dirent *dp;
  62   register DIR *dir;
  63   register dev_t dev;
  64   register ino_t ino;
  65   register int first;
  66   register char *bpt, *bup;
  67   struct stat s;
  68   dev_t root_dev;
  69   ino_t root_ino;
  70   size_t ptsize, upsize;
  71   int save_errno;
  72   char *ept, *eup, *up;
  73
  74   /*
  75    * If no buffer specified by the user, allocate one as necessary.
  76    * If a buffer is specified, the size has to be non-zero.  The path
  77    * is built from the end of the buffer backwards.
  78    */
  79
  80   if (pt)
  81     {
  82       ptsize = 0;
  83       if (!size)
  84         {
  85           errno = EINVAL;
  86           return (char *) NULL;
  87         }
  88       ept = pt + size;
  89     }
  90   else
  91     {
  92       if (!(pt = (char *) malloc (ptsize = 1024 - 4)))
  93         {
  94           return (char *) NULL;
  95         }
  96       ept = pt + ptsize;
  97     }
  98   bpt = ept - 1;
  99   *bpt = '\0';
 100
 101   /*
 102    * Allocate bytes (1024 - malloc space) for the string of "../"'s.
 103    * Should always be enough (it's 340 levels).  If it's not, allocate
 104    * as necessary.  Special * case the first stat, it's ".", not "..".
 105    */
 106
 107   if (!(up = (char *) malloc (upsize = 1024 - 4)))
 108     {
 109       goto err;
 110     }
 111   eup = up + MAXPATHLEN;
 112   bup = up;
 113   up[0] = '.';
 114   up[1] = '\0';
 115
 116   /* Save root values, so know when to stop. */
 117   if (stat ("/", &s))
 118     goto err;
 119   root_dev = s.st_dev;
 120   root_ino = s.st_ino;
 121
 122   errno = 0;                    /* XXX readdir has no error return. */
 123
 124   for (first = 1;; first = 0)
 125     {
 126       /* Stat the current level. */
 127       if (_stat (up, &s))
 128         goto err;
 129
 130       /* Save current node values. */
 131       ino = s.st_ino;
 132       dev = s.st_dev;
 133
 134       /* Check for reaching root. */
 135       if (root_dev == dev && root_ino == ino)
 136         {
 137           *--bpt = '/';
 138           /*
 139            * It's unclear that it's a requirement to copy the
 140            * path to the beginning of the buffer, but it's always
 141            * been that way and stuff would probably break.
 142            */
 143           (void) bcopy (bpt, pt, ept - bpt);
 144           free (up);
 145           return pt;
 146         }
 147
 148       /*
 149        * Build pointer to the parent directory, allocating memory
 150        * as necessary.  Max length is 3 for "../", the largest
 151        * possible component name, plus a trailing NULL.
 152        */
 153
 154       if (bup + 3 + MAXNAMLEN + 1 >= eup)
 155         {
 156           if (!(up = (char *) realloc (up, upsize *= 2)))
 157             {
 158               goto err;
 159             }
 160           bup = up;
 161           eup = up + upsize;
 162         }
 163       *bup++ = '.';
 164       *bup++ = '.';
 165       *bup = '\0';
 166
 167       /* Open and stat parent directory. */
 168       if (!(dir = _opendir (up)) || _fstat (__dirfd (dir), &s))
 169         goto err;
 170
 171       /* Add trailing slash for next directory. */
 172       *bup++ = '/';
 173
 174       /*
 175        * If it's a mount point, have to stat each element because
 176        * the inode number in the directory is for the entry in the
 177        * parent directory, not the inode number of the mounted file.
 178        */
 179
 180       save_errno = 0;
 181       if (s.st_dev == dev)
 182         {
 183           for (;;)
 184             {
 185               if (!(dp = _readdir (dir)))
 186                 goto notfound;
 187               if (dp->d_ino == ino)
 188                 break;
 189             }
 190         }
 191       else
 192         for (;;)
 193           {
 194             if (!(dp = _readdir (dir)))
 195               goto notfound;
 196             if (ISDOT (dp))
 197               continue;
 198             bcopy (dp->d_name, bup, strlen (dp->d_name) + 1);
 199
 200             /* Save the first error for later. */
 201             if (stat (up, &s))
 202               {
 203                 if (!save_errno)
 204                   save_errno = errno;
 205                 errno = 0;
 206                 continue;
 207               }
 208             if (s.st_dev == dev && s.st_ino == ino)
 209               break;
 210           }
 211
 212       /*
 213        * Check for length of the current name, preceding slash,
 214        * leading slash.
 215        */
 216
 217       if (bpt - pt <= strlen (dp->d_name) + (first ? 1 : 2))
 218         {
 219           size_t len, off;
 220
 221           if (!ptsize)
 222             {
 223               errno = ERANGE;
 224               goto err;
 225             }
 226           off = bpt - pt;
 227           len = ept - bpt;
 228           if (!(pt = (char *) realloc (pt, ptsize *= 2)))
 229             {
 230               goto err;
 231             }
 232           bpt = pt + off;
 233           ept = pt + ptsize;
 234           (void) bcopy (bpt, ept - len, len);
 235           bpt = ept - len;
 236         }
 237       if (!first)
 238         *--bpt = '/';
 239       bpt -= strlen (dp->d_name);
 240       bcopy (dp->d_name, bpt, strlen (dp->d_name));
 241       (void) _closedir (dir);
 242
 243       /* Truncate any file name. */
 244       *bup = '\0';
 245     }
 246
 247 notfound:
 248   /*
 249    * If readdir set errno, use it, not any saved error; otherwise,
 250    * didn't find the current directory in its parent directory, set
 251    * errno to ENOENT.
 252    */
 253
 254   if (!errno)
 255     errno = save_errno ? save_errno : ENOENT;
 256   /* FALLTHROUGH */
 257
 258 err:
 259   if (ptsize)
 260     free (pt);
 261   free (up);
 262   return (char *) NULL;
 263 }
 264
 265 #endif /* _REENT_ONLY */