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 1.24 2003/01/10 02:58:25 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     !defined(__NETBSD_SYSCALLS)
  99         if (__getcwd(pt, ept - pt) == 0) {
 100                 if (*pt != '/') {
 101                         bpt = pt;
 102                         ept = pt + strlen(pt) - 1;
 103                         while (bpt < ept) {
 104                                 c = *bpt;
 105                                 *bpt++ = *ept;
 106                                 *ept-- = c;
 107                         }
 108                 }
 109                 return (pt);
 110         }
 111 #endif
 112         bpt = ept - 1;
 113         *bpt = '\0';
 114
 115         /*
 116          * Allocate bytes (1024 - malloc space) for the string of "../"'s.
 117          * Should always be enough (it's 340 levels).  If it's not, allocate
 118          * as necessary.  Special case the first stat, it's ".", not "..".
 119          */
 120         if ((up = malloc(upsize = 1024 - 4)) == NULL)
 121                 goto err;
 122         eup = up + MAXPATHLEN;
 123         bup = up;
 124         up[0] = '.';
 125         up[1] = '\0';
 126
 127         /* Save root values, so know when to stop. */
 128         if (stat("/", &s))
 129                 goto err;
 130         root_dev = s.st_dev;
 131         root_ino = s.st_ino;
 132
 133         errno = 0;                      /* XXX readdir has no error return. */
 134
 135         for (first = 1;; first = 0) {
 136                 /* Stat the current level. */
 137                 if (lstat(up, &s))
 138                         goto err;
 139
 140                 /* Save current node values. */
 141                 ino = s.st_ino;
 142                 dev = s.st_dev;
 143
 144                 /* Check for reaching root. */
 145                 if (root_dev == dev && root_ino == ino) {
 146                         *--bpt = '/';
 147                         /*
 148                          * It's unclear that it's a requirement to copy the
 149                          * path to the beginning of the buffer, but it's always
 150                          * been that way and stuff would probably break.
 151                          */
 152                         bcopy(bpt, pt, ept - bpt);
 153                         free(up);
 154                         return (pt);
 155                 }
 156
 157                 /*
 158                  * Build pointer to the parent directory, allocating memory
 159                  * as necessary.  Max length is 3 for "../", the largest
 160                  * possible component name, plus a trailing NUL.
 161                  */
 162                 if (bup + 3  + MAXNAMLEN + 1 >= eup) {
 163                         if ((up = reallocf(up, upsize *= 2)) == NULL)
 164                                 goto err;
 165                         bup = up;
 166                         eup = up + upsize;
 167                 }
 168                 *bup++ = '.';
 169                 *bup++ = '.';
 170                 *bup = '\0';
 171
 172                 /* Open and stat parent directory. */
 173                 if (!(dir = opendir(up)) || _fstat(dirfd(dir), &s))
 174                         goto err;
 175
 176                 /* Add trailing slash for next directory. */
 177                 *bup++ = '/';
 178                 *bup = '\0';
 179
 180                 /*
 181                  * If it's a mount point, have to stat each element because
 182                  * the inode number in the directory is for the entry in the
 183                  * parent directory, not the inode number of the mounted file.
 184                  */
 185                 save_errno = 0;
 186                 if (s.st_dev == dev) {
 187                         for (;;) {
 188                                 if (!(dp = readdir(dir)))
 189                                         goto notfound;
 190                                 if (dp->d_fileno == ino)
 191                                         break;
 192                         }
 193                 } else
 194                         for (;;) {
 195                                 if (!(dp = readdir(dir)))
 196                                         goto notfound;
 197                                 if (ISDOT(dp))
 198                                         continue;
 199                                 bcopy(dp->d_name, bup, dp->d_namlen + 1);
 200
 201                                 /* Save the first error for later. */
 202                                 if (lstat(up, &s)) {
 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                 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
 217                         size_t len, off;
 218
 219                         if (!ptsize) {
 220                                 errno = ERANGE;
 221                                 goto err;
 222                         }
 223                         off = bpt - pt;
 224                         len = ept - bpt;
 225                         if ((pt = reallocf(pt, ptsize *= 2)) == NULL)
 226                                 goto err;
 227                         bpt = pt + off;
 228                         ept = pt + ptsize;
 229                         bcopy(bpt, ept - len, len);
 230                         bpt = ept - len;
 231                 }
 232                 if (!first)
 233                         *--bpt = '/';
 234                 bpt -= dp->d_namlen;
 235                 bcopy(dp->d_name, bpt, dp->d_namlen);
 236                 (void) closedir(dir);
 237                 dir = NULL;
 238
 239                 /* Truncate any file name. */
 240                 *bup = '\0';
 241         }
 242
 243 notfound:
 244         /*
 245          * If readdir set errno, use it, not any saved error; otherwise,
 246          * didn't find the current directory in its parent directory, set
 247          * errno to ENOENT.
 248          */
 249         if (!errno)
 250                 errno = save_errno ? save_errno : ENOENT;
 251         /* FALLTHROUGH */
 252 err:
 253         save_errno = errno;
 254
 255         if (ptsize)
 256                 free(pt);
 257         if (dir)
 258                 (void) closedir(dir);
 259         free(up);
 260
 261         errno = save_errno;
 262         return (NULL);
 263 }