gen/FreeBSD/getcwd.c

   1 /*
   2  * Copyright (c) 1989, 1991, 1993, 1995
   3  *      The Regents of the University of California.  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    8.5 (Berkeley) 2/7/95";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/gen/getcwd.c,v 1.25 2003/10/29 10:45:01 tjr Exp $");
  39
  40 #include "namespace.h"
  41 #include <sys/param.h>
  42 #include <sys/stat.h>
  43
  44 #include <dirent.h>
  45 #include <errno.h>
  46 #include <fcntl.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51 #include "un-namespace.h"
  52
  53 #define ISDOT(dp) \
  54         (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
  55             (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
  56
  57 extern int __getcwd(char *, size_t);
  58
  59 char *
  60 getcwd(pt, size)
  61         char *pt;
  62         size_t size;
  63 {
  64         struct dirent *dp;
  65         DIR *dir = NULL;
  66         dev_t dev;
  67         ino_t ino;
  68         int first;
  69         char *bpt, *bup;
  70         struct stat s;
  71         dev_t root_dev;
  72         ino_t root_ino;
  73         size_t ptsize, upsize;
  74         int save_errno;
  75         char *ept, *eup, *up, c;
  76
  77         /*
  78          * If no buffer specified by the user, allocate one as necessary.
  79          * If a buffer is specified, the size has to be non-zero.  The path
  80          * is built from the end of the buffer backwards.
  81          */
  82         if (pt) {
  83                 ptsize = 0;
  84                 if (!size) {
  85                         errno = EINVAL;
  86                         return (NULL);
  87                 }
  88                 if (size == 1) {
  89                         errno = ERANGE;
  90                         return (NULL);
  91                 }
  92                 ept = pt + size;
  93         } else {
  94                 if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
  95                         return (NULL);
  96                 ept = pt + ptsize;
  97         }
  98         if (__getcwd(pt, ept - pt) == 0) {
  99                 if (*pt != '/') {
 100                         bpt = pt;
 101                         ept = pt + strlen(pt) - 1;
 102                         while (bpt < ept) {
 103                                 c = *bpt;
 104                                 *bpt++ = *ept;
 105                                 *ept-- = c;
 106                         }
 107                 }
 108                 return (pt);
 109         }
 110         bpt = ept - 1;
 111         *bpt = '\0';
 112
 113         /*
 114          * Allocate bytes (1024 - malloc space) for the string of "../"'s.
 115          * Should always be enough (it's 340 levels).  If it's not, allocate
 116          * as necessary.  Special case the first stat, it's ".", not "..".
 117          */
 118         if ((up = malloc(upsize = 1024 - 4)) == NULL)
 119                 goto err;
 120         eup = up + MAXPATHLEN;
 121         bup = up;
 122         up[0] = '.';
 123         up[1] = '\0';
 124
 125         /* Save root values, so know when to stop. */
 126         if (stat("/", &s))
 127                 goto err;
 128         root_dev = s.st_dev;
 129         root_ino = s.st_ino;
 130
 131         errno = 0;                      /* XXX readdir has no error return. */
 132
 133         for (first = 1;; first = 0) {
 134                 /* Stat the current level. */
 135                 if (lstat(up, &s))
 136                         goto err;
 137
 138                 /* Save current node values. */
 139                 ino = s.st_ino;
 140                 dev = s.st_dev;
 141
 142                 /* Check for reaching root. */
 143                 if (root_dev == dev && root_ino == ino) {
 144                         *--bpt = '/';
 145                         /*
 146                          * It's unclear that it's a requirement to copy the
 147                          * path to the beginning of the buffer, but it's always
 148                          * been that way and stuff would probably break.
 149                          */
 150                         bcopy(bpt, pt, ept - bpt);
 151                         free(up);
 152                         return (pt);
 153                 }
 154
 155                 /*
 156                  * Build pointer to the parent directory, allocating memory
 157                  * as necessary.  Max length is 3 for "../", the largest
 158                  * possible component name, plus a trailing NUL.
 159                  */
 160                 if (bup + 3  + MAXNAMLEN + 1 >= eup) {
 161                         if ((up = reallocf(up, upsize *= 2)) == NULL)
 162                                 goto err;
 163                         bup = up;
 164                         eup = up + upsize;
 165                 }
 166                 *bup++ = '.';
 167                 *bup++ = '.';
 168                 *bup = '\0';
 169
 170                 /* Open and stat parent directory. */
 171                 if (!(dir = opendir(up)) || _fstat(dirfd(dir), &s))
 172                         goto err;
 173
 174                 /* Add trailing slash for next directory. */
 175                 *bup++ = '/';
 176                 *bup = '\0';
 177
 178                 /*
 179                  * If it's a mount point, have to stat each element because
 180                  * the inode number in the directory is for the entry in the
 181                  * parent directory, not the inode number of the mounted file.
 182                  */
 183                 save_errno = 0;
 184                 if (s.st_dev == dev) {
 185                         for (;;) {
 186                                 if (!(dp = readdir(dir)))
 187                                         goto notfound;
 188                                 if (dp->d_fileno == ino)
 189                                         break;
 190                         }
 191                 } else
 192                         for (;;) {
 193                                 if (!(dp = readdir(dir)))
 194                                         goto notfound;
 195                                 if (ISDOT(dp))
 196                                         continue;
 197                                 bcopy(dp->d_name, bup, dp->d_namlen + 1);
 198
 199                                 /* Save the first error for later. */
 200                                 if (lstat(up, &s)) {
 201                                         if (!save_errno)
 202                                                 save_errno = errno;
 203                                         errno = 0;
 204                                         continue;
 205                                 }
 206                                 if (s.st_dev == dev && s.st_ino == ino)
 207                                         break;
 208                         }
 209
 210                 /*
 211                  * Check for length of the current name, preceding slash,
 212                  * leading slash.
 213                  */
 214                 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
 215                         size_t len, off;
 216
 217                         if (!ptsize) {
 218                                 errno = ERANGE;
 219                                 goto err;
 220                         }
 221                         off = bpt - pt;
 222                         len = ept - bpt;
 223                         if ((pt = reallocf(pt, ptsize *= 2)) == NULL)
 224                                 goto err;
 225                         bpt = pt + off;
 226                         ept = pt + ptsize;
 227                         bcopy(bpt, ept - len, len);
 228                         bpt = ept - len;
 229                 }
 230                 if (!first)
 231                         *--bpt = '/';
 232                 bpt -= dp->d_namlen;
 233                 bcopy(dp->d_name, bpt, dp->d_namlen);
 234                 (void) closedir(dir);
 235                 dir = NULL;
 236
 237                 /* Truncate any file name. */
 238                 *bup = '\0';
 239         }
 240
 241 notfound:
 242         /*
 243          * If readdir set errno, use it, not any saved error; otherwise,
 244          * didn't find the current directory in its parent directory, set
 245          * errno to ENOENT.
 246          */
 247         if (!errno)
 248                 errno = save_errno ? save_errno : ENOENT;
 249         /* FALLTHROUGH */
 250 err:
 251         save_errno = errno;
 252
 253         if (ptsize)
 254                 free(pt);
 255         if (dir)
 256                 (void) closedir(dir);
 257         free(up);
 258
 259         errno = save_errno;
 260         return (NULL);
 261 }