regress/sys/kern/getcwd/old_getcwd.c

   1 /*      $NetBSD: old_getcwd.c,v 1.2 2002/02/21 07:38:20 itojun Exp $    */
   2
   3 /*
   4  * Copyright (c) 1989, 1991, 1993, 1995
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Jan-Simon Pendry.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * This file copied from NetBSD's src/lib/libc/gen/getcwd.c 1.15, and edited
  37  * to remove namespace stuff and the unused realpath function.
  38  */
  39
  40
  41 #include <sys/cdefs.h>
  42 #if defined(LIBC_SCCS) && !defined(lint)
  43 #if 0
  44 static char sccsid[] = "@(#)getcwd.c    8.5 (Berkeley) 2/7/95";
  45 #else
  46 __RCSID("$NetBSD: old_getcwd.c,v 1.2 2002/02/21 07:38:20 itojun Exp $");
  47 #endif
  48 #endif /* LIBC_SCCS and not lint */
  49
  50 #include <sys/param.h>
  51 #include <sys/stat.h>
  52
  53 #include <dirent.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60
  61 #include "getcwd.h"
  62
  63 #define ISDOT(dp) \
  64         (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
  65             (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
  66
  67
  68 #if defined(__SVR4) || defined(__svr4__)
  69 #define d_fileno d_ino
  70 #endif
  71
  72 char *
  73 old_getcwd(pt, size)
  74         char *pt;
  75         size_t size;
  76 {
  77         struct dirent *dp;
  78         DIR *dir;
  79         dev_t dev;
  80         ino_t ino;
  81         int first;
  82         char *bpt, *bup;
  83         struct stat s;
  84         dev_t root_dev;
  85         ino_t root_ino;
  86         size_t ptsize, upsize;
  87         int save_errno;
  88         char *ept, *eup, *up;
  89         size_t dlen;
  90
  91         /*
  92          * If no buffer specified by the user, allocate one as necessary.
  93          * If a buffer is specified, the size has to be non-zero.  The path
  94          * is built from the end of the buffer backwards.
  95          */
  96         if (pt) {
  97                 ptsize = 0;
  98                 if (!size) {
  99                         errno = EINVAL;
 100                         return (NULL);
 101                 }
 102                 ept = pt + size;
 103         } else {
 104                 if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
 105                         return (NULL);
 106                 ept = pt + ptsize;
 107         }
 108         bpt = ept - 1;
 109         *bpt = '\0';
 110
 111         /*
 112          * Allocate bytes (1024 - malloc space) for the string of "../"'s.
 113          * Should always be enough (it's 340 levels).  If it's not, allocate
 114          * as necessary.  Special case the first stat, it's ".", not "..".
 115          */
 116         if ((up = malloc(upsize = 1024 - 4)) == NULL)
 117                 goto err;
 118         eup = up + MAXPATHLEN;
 119         bup = up;
 120         up[0] = '.';
 121         up[1] = '\0';
 122
 123         /* Save root values, so know when to stop. */
 124         if (stat("/", &s))
 125                 goto err;
 126         root_dev = s.st_dev;
 127         root_ino = s.st_ino;
 128
 129         errno = 0;                      /* XXX readdir has no error return. */
 130
 131         for (first = 1;; first = 0) {
 132                 /* Stat the current level. */
 133                 if (lstat(up, &s))
 134                         goto err;
 135
 136                 /* Save current node values. */
 137                 ino = s.st_ino;
 138                 dev = s.st_dev;
 139
 140                 /* Check for reaching root. */
 141                 if (root_dev == dev && root_ino == ino) {
 142                         *--bpt = '/';
 143                         /*
 144                          * It's unclear that it's a requirement to copy the
 145                          * path to the beginning of the buffer, but it's always
 146                          * been that way and stuff would probably break.
 147                          */
 148                         memmove(pt, bpt,  (size_t)(ept - bpt));
 149                         free(up);
 150                         return (pt);
 151                 }
 152
 153                 /*
 154                  * Build pointer to the parent directory, allocating memory
 155                  * as necessary.  Max length is 3 for "../", the largest
 156                  * possible component name, plus a trailing NULL.
 157                  */
 158                 if (bup + 3  + MAXNAMLEN + 1 >= eup) {
 159                         if ((up = realloc(up, upsize *= 2)) == NULL)
 160                                 goto err;
 161                         bup = up;
 162                         eup = up + upsize;
 163                 }
 164                 *bup++ = '.';
 165                 *bup++ = '.';
 166                 *bup = '\0';
 167
 168                 /* Open and stat parent directory. */
 169                 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
 170                         goto err;
 171
 172                 /* Add trailing slash for next directory. */
 173                 *bup++ = '/';
 174
 175                 /*
 176                  * If it's a mount point, have to stat each element because
 177                  * the inode number in the directory is for the entry in the
 178                  * parent directory, not the inode number of the mounted file.
 179                  */
 180                 save_errno = 0;
 181                 if (s.st_dev == dev) {
 182                         for (;;) {
 183                                 if (!(dp = readdir(dir)))
 184                                         goto notfound;
 185                                 if (dp->d_fileno == ino) {
 186 #if defined(__SVR4) || defined(__svr4__)
 187                                         dlen = strlen(dp->d_name);
 188 #else
 189                                         dlen = dp->d_namlen;
 190 #endif
 191                                         break;
 192                                 }
 193                         }
 194                 } else
 195                         for (;;) {
 196                                 if (!(dp = readdir(dir)))
 197                                         goto notfound;
 198                                 if (ISDOT(dp))
 199                                         continue;
 200 #if defined(__SVR4) || defined(__svr4__)
 201                                 dlen = strlen(dp->d_name);
 202 #else
 203                                 dlen = dp->d_namlen;
 204 #endif
 205                                 memmove(bup, dp->d_name, dlen + 1);
 206
 207                                 /* Save the first error for later. */
 208                                 if (lstat(up, &s)) {
 209                                         if (!save_errno)
 210                                                 save_errno = errno;
 211                                         errno = 0;
 212                                         continue;
 213                                 }
 214                                 if (s.st_dev == dev && s.st_ino == ino)
 215                                         break;
 216                         }
 217
 218                 /*
 219                  * Check for length of the current name, preceding slash,
 220                  * leading slash.
 221                  */
 222                 if (bpt - pt <= dlen + (first ? 1 : 2)) {
 223                         size_t len, off;
 224
 225                         if (!ptsize) {
 226                                 errno = ERANGE;
 227                                 goto err;
 228                         }
 229                         off = bpt - pt;
 230                         len = ept - bpt;
 231                         if ((pt = realloc(pt, ptsize *= 2)) == NULL)
 232                                 goto err;
 233                         bpt = pt + off;
 234                         ept = pt + ptsize;
 235                         memmove(ept - len, bpt, len);
 236                         bpt = ept - len;
 237                 }
 238                 if (!first)
 239                         *--bpt = '/';
 240                 bpt -= dlen;
 241                 memmove(bpt, dp->d_name, dlen);
 242                 (void)closedir(dir);
 243
 244                 /* Truncate any file name. */
 245                 *bup = '\0';
 246         }
 247
 248 notfound:
 249         /*
 250          * If readdir set errno, use it, not any saved error; otherwise,
 251          * didn't find the current directory in its parent directory, set
 252          * errno to ENOENT.
 253          */
 254         if (!errno)
 255                 errno = save_errno ? save_errno : ENOENT;
 256         /* FALLTHROUGH */
 257 err:
 258         if (ptsize)
 259                 free(pt);
 260         free(up);
 261         return (NULL);
 262 }