clib

getcwd2.c

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00001 /*-
00002  * See the file LICENSE for redistribution information.
00003  *
00004  * Copyright (c) 1996, 1997, 1998, 1999
00005  * Sleepycat Software. All rights reserved.
00006  */
00007 /*
00008  * Copyright (c) 1989, 1991, 1993
00009  * The Regents of the University of California. All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without
00012  * modification, are permitted provided that the following conditions
00013  * are met:
00014  * 1. Redistributions of source code must retain the above copyright
00015  * notice, this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright
00017  * notice, this list of conditions and the following disclaimer in the
00018  * documentation and/or other materials provided with the distribution.
00019  * 3. Neither the name of the University nor the names of its contributors
00020  * may be used to endorse or promote products derived from this software
00021  * without specific prior written permission.
00022  *
00023  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00024  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00025  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00026  * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00027  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00028  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00029  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00030  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00031  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00032  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00033  * SUCH DAMAGE.
00034  */
00035 
00036 #ifdef HAVE_CONFIG_H
00037 #include "config.h"
00038 #endif /* HAVE_CONFIG_H */
00039 
00040 #include <sys/types.h>
00041 #include <sys/stat.h>
00042 
00043 #if HAVE_DIRENT_H
00044 # include <dirent.h>
00045 # define NAMLEN(dirent) strlen((dirent)->d_name)
00046 #else
00047 # define dirent direct
00048 # define NAMLEN(dirent) (dirent)->d_namlen
00049 # if HAVE_SYS_NDIR_H
00050 # include <sys/ndir.h>
00051 # endif
00052 # if HAVE_SYS_DIR_H
00053 # include <sys/dir.h>
00054 # endif
00055 # if HAVE_NDIR_H
00056 # include <ndir.h>
00057 # endif
00058 #endif
00059 
00060 #include <errno.h>
00061 #include <stdio.h>
00062 #include <stdlib.h>
00063 #include <string.h>
00064 #include <unistd.h>
00065 
00066 #ifndef HAVE_GETCWD
00067 
00068 #define ISDOT(dp) \
00069  (dp->d_name[0] == '.' && (dp->d_name[1] == '0円' || \
00070  (dp->d_name[1] == '.' && dp->d_name[2] == '0円')))
00071 
00072 #ifndef dirfd
00073 #define dirfd(dirp) ((dirp)->dd_fd)
00074 #endif
00075 
00076 /*
00077  * getcwd --
00078  * Get the current working directory.
00079  *
00080  * PUBLIC: #ifndef HAVE_GETCWD
00081  * PUBLIC: char *getcwd __P((char *, size_t));
00082  * PUBLIC: #endif
00083  */
00084 char *
00085 getcwd(pt, size)
00086 char *pt;
00087 size_t size;
00088 {
00089 register struct dirent *dp;
00090 register DIR *dir;
00091 register dev_t dev;
00092 register ino_t ino;
00093 register int first;
00094 register char *bpt, *bup;
00095 struct stat s;
00096 dev_t root_dev;
00097 ino_t root_ino;
00098 size_t ptsize, upsize;
00099 int ret, save_errno;
00100 char *ept, *eup, *up;
00101 
00102 /*
00103  * If no buffer specified by the user, allocate one as necessary.
00104  * If a buffer is specified, the size has to be non-zero. The path
00105  * is built from the end of the buffer backwards.
00106  */
00107 if (pt) {
00108 ptsize = 0;
00109 if (!size) {
00110 __os_set_errno(EINVAL);
00111 return (NULL);
00112 }
00113 if (size == 1) {
00114 __os_set_errno(ERANGE);
00115 return (NULL);
00116 }
00117 ept = pt + size;
00118 } else {
00119 if ((ret = __os_malloc(ptsize = 1024 - 4, NULL, &pt)) != 0) {
00120 __os_set_errno(ret);
00121 return (NULL);
00122 }
00123 ept = pt + ptsize;
00124 }
00125 bpt = ept - 1;
00126 *bpt = '0円';
00127 
00128 /*
00129  * Allocate bytes (1024 - malloc space) for the string of "../"'s.
00130  * Should always be enough (it's 340 levels). If it's not, allocate
00131  * as necessary. Special case the first stat, it's ".", not "..".
00132  */
00133 if ((ret = __os_malloc(upsize = 1024 - 4, NULL, &up)) != 0)
00134 goto err;
00135 eup = up + 1024;
00136 bup = up;
00137 up[0] = '.';
00138 up[1] = '0円';
00139 
00140 /* Save root values, so know when to stop. */
00141 if (stat("/", &s))
00142 goto err;
00143 root_dev = s.st_dev;
00144 root_ino = s.st_ino;
00145 
00146 __os_set_errno(0); /* XXX readdir has no error return. */
00147 
00148 for (first = 1;; first = 0) {
00149 /* Stat the current level. */
00150 if (lstat(up, &s))
00151 goto err;
00152 
00153 /* Save current node values. */
00154 ino = s.st_ino;
00155 dev = s.st_dev;
00156 
00157 /* Check for reaching root. */
00158 if (root_dev == dev && root_ino == ino) {
00159 *--bpt = PATH_SEPARATOR[0];
00160 /*
00161  * It's unclear that it's a requirement to copy the
00162  * path to the beginning of the buffer, but it's always
00163  * been that way and stuff would probably break.
00164  */
00165 bcopy(bpt, pt, ept - bpt);
00166 __os_free(up, upsize);
00167 return (pt);
00168 }
00169 
00170 /*
00171  * Build pointer to the parent directory, allocating memory
00172  * as necessary. Max length is 3 for "../", the largest
00173  * possible component name, plus a trailing NULL.
00174  */
00175 if (bup + 3 + MAXNAMLEN + 1 >= eup) {
00176 if (__os_realloc(upsize *= 2, NULL, &up) != 0)
00177 goto err;
00178 bup = up;
00179 eup = up + upsize;
00180 }
00181 *bup++ = '.';
00182 *bup++ = '.';
00183 *bup = '0円';
00184 
00185 /* Open and stat parent directory. */
00186 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
00187 goto err;
00188 
00189 /* Add trailing slash for next directory. */
00190 *bup++ = PATH_SEPARATOR[0];
00191 
00192 /*
00193  * If it's a mount point, have to stat each element because
00194  * the inode number in the directory is for the entry in the
00195  * parent directory, not the inode number of the mounted file.
00196  */
00197 save_errno = 0;
00198 if (s.st_dev == dev) {
00199 for (;;) {
00200 if (!(dp = readdir(dir)))
00201 goto notfound;
00202 if (dp->d_fileno == ino)
00203 break;
00204 }
00205 } else
00206 for (;;) {
00207 if (!(dp = readdir(dir)))
00208 goto notfound;
00209 if (ISDOT(dp))
00210 continue;
00211 bcopy(dp->d_name, bup, dp->d_namlen + 1);
00212 
00213 /* Save the first error for later. */
00214 if (lstat(up, &s)) {
00215 if (save_errno == 0)
00216 save_errno = __os_get_errno();
00217 __os_set_errno(0);
00218 continue;
00219 }
00220 if (s.st_dev == dev && s.st_ino == ino)
00221 break;
00222 }
00223 
00224 /*
00225  * Check for length of the current name, preceding slash,
00226  * leading slash.
00227  */
00228 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
00229 size_t len, off;
00230 
00231 if (!ptsize) {
00232 __os_set_errno(ERANGE);
00233 goto err;
00234 }
00235 off = bpt - pt;
00236 len = ept - bpt;
00237 if (__os_realloc(ptsize *= 2, NULL, &pt) != 0)
00238 goto err;
00239 bpt = pt + off;
00240 ept = pt + ptsize;
00241 bcopy(bpt, ept - len, len);
00242 bpt = ept - len;
00243 }
00244 if (!first)
00245 *--bpt = PATH_SEPARATOR[0];
00246 bpt -= dp->d_namlen;
00247 bcopy(dp->d_name, bpt, dp->d_namlen);
00248 (void)closedir(dir);
00249 
00250 /* Truncate any file name. */
00251 *bup = '0円';
00252 }
00253 
00254 notfound:
00255 /*
00256  * If readdir set errno, use it, not any saved error; otherwise,
00257  * didn't find the current directory in its parent directory, set
00258  * errno to ENOENT.
00259  */
00260 if (__os_get_errno() == 0)
00261 __os_set_errno(save_errno == 0 ? ENOENT : save_errno);
00262 /* FALLTHROUGH */
00263 err:
00264 if (ptsize)
00265 __os_free(pt, ptsize);
00266 __os_free(up, upsize);
00267 return (NULL);
00268 }
00269 #endif /* HAVE_GETCWD */

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