getcwd2.c

Go to the documentation of this file.

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999
 *      Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1989, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

#include <sys/types.h>
#include <sys/stat.h>

#if HAVE_DIRENT_H
# include <dirent.h>
# define NAMLEN(dirent) strlen((dirent)->d_name)
#else
# define dirent direct
# define NAMLEN(dirent) (dirent)->d_namlen
# if HAVE_SYS_NDIR_H
#  include <sys/ndir.h>
# endif
# if HAVE_SYS_DIR_H
#  include <sys/dir.h>
# endif
# if HAVE_NDIR_H
#  include <ndir.h>
# endif
#endif

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifndef HAVE_GETCWD

#define ISDOT(dp) \
        (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
            (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))

#ifndef dirfd
#define   dirfd(dirp)     ((dirp)->dd_fd)
#endif

/*
 * getcwd --
 *      Get the current working directory.
 *
 * PUBLIC: #ifndef HAVE_GETCWD
 * PUBLIC: char *getcwd __P((char *, size_t));
 * PUBLIC: #endif
 */
char *
getcwd(pt, size)
        char *pt;
        size_t size;
{
        register struct dirent *dp;
        register DIR *dir;
        register dev_t dev;
        register ino_t ino;
        register int first;
        register char *bpt, *bup;
        struct stat s;
        dev_t root_dev;
        ino_t root_ino;
        size_t ptsize, upsize;
        int ret, save_errno;
        char *ept, *eup, *up;

        /*
         * If no buffer specified by the user, allocate one as necessary.
         * If a buffer is specified, the size has to be non-zero.  The path
         * is built from the end of the buffer backwards.
         */
        if (pt) {
                ptsize = 0;
                if (!size) {
                        __os_set_errno(EINVAL);
                        return (NULL);
                }
                if (size == 1) {
                        __os_set_errno(ERANGE);
                        return (NULL);
                }
                ept = pt + size;
        } else {
                if ((ret = __os_malloc(ptsize = 1024 - 4, NULL, &pt)) != 0) {
                        __os_set_errno(ret);
                        return (NULL);
                }
                ept = pt + ptsize;
        }
        bpt = ept - 1;
        *bpt = '\0';

        /*
         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
         * Should always be enough (it's 340 levels).  If it's not, allocate
         * as necessary.  Special case the first stat, it's ".", not "..".
         */
        if ((ret = __os_malloc(upsize = 1024 - 4, NULL, &up)) != 0)
                goto err;
        eup = up + 1024;
        bup = up;
        up[0] = '.';
        up[1] = '\0';

        /* Save root values, so know when to stop. */
        if (stat("/", &s))
                goto err;
        root_dev = s.st_dev;
        root_ino = s.st_ino;

        __os_set_errno(0);              /* XXX readdir has no error return. */

        for (first = 1;; first = 0) {
                /* Stat the current level. */
                if (lstat(up, &s))
                        goto err;

                /* Save current node values. */
                ino = s.st_ino;
                dev = s.st_dev;

                /* Check for reaching root. */
                if (root_dev == dev && root_ino == ino) {
                        *--bpt = PATH_SEPARATOR[0];
                        /*
                         * It's unclear that it's a requirement to copy the
                         * path to the beginning of the buffer, but it's always
                         * been that way and stuff would probably break.
                         */
                        bcopy(bpt, pt, ept - bpt);
                        __os_free(up, upsize);
                        return (pt);
                }

                /*
                 * Build pointer to the parent directory, allocating memory
                 * as necessary.  Max length is 3 for "../", the largest
                 * possible component name, plus a trailing NULL.
                 */
                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
                        if (__os_realloc(upsize *= 2, NULL, &up) != 0)
                                goto err;
                        bup = up;
                        eup = up + upsize;
                }
                *bup++ = '.';
                *bup++ = '.';
                *bup = '\0';

                /* Open and stat parent directory. */
                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                        goto err;

                /* Add trailing slash for next directory. */
                *bup++ = PATH_SEPARATOR[0];

                /*
                 * If it's a mount point, have to stat each element because
                 * the inode number in the directory is for the entry in the
                 * parent directory, not the inode number of the mounted file.
                 */
                save_errno = 0;
                if (s.st_dev == dev) {
                        for (;;) {
                                if (!(dp = readdir(dir)))
                                        goto notfound;
                                if (dp->d_fileno == ino)
                                        break;
                        }
                } else
                        for (;;) {
                                if (!(dp = readdir(dir)))
                                        goto notfound;
                                if (ISDOT(dp))
                                        continue;
                                bcopy(dp->d_name, bup, dp->d_namlen + 1);

                                /* Save the first error for later. */
                                if (lstat(up, &s)) {
                                        if (save_errno == 0)
                                                save_errno = __os_get_errno();
                                        __os_set_errno(0);
                                        continue;
                                }
                                if (s.st_dev == dev && s.st_ino == ino)
                                        break;
                        }

                /*
                 * Check for length of the current name, preceding slash,
                 * leading slash.
                 */
                if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
                        size_t len, off;

                        if (!ptsize) {
                                __os_set_errno(ERANGE);
                                goto err;
                        }
                        off = bpt - pt;
                        len = ept - bpt;
                        if (__os_realloc(ptsize *= 2, NULL, &pt) != 0)
                                goto err;
                        bpt = pt + off;
                        ept = pt + ptsize;
                        bcopy(bpt, ept - len, len);
                        bpt = ept - len;
                }
                if (!first)
                        *--bpt = PATH_SEPARATOR[0];
                bpt -= dp->d_namlen;
                bcopy(dp->d_name, bpt, dp->d_namlen);
                (void)closedir(dir);

                /* Truncate any file name. */
                *bup = '\0';
        }

notfound:
        /*
         * If readdir set errno, use it, not any saved error; otherwise,
         * didn't find the current directory in its parent directory, set
         * errno to ENOENT.
         */
        if (__os_get_errno() == 0)
                __os_set_errno(save_errno == 0 ? ENOENT : save_errno);
        /* FALLTHROUGH */
err:
        if (ptsize)
                __os_free(pt, ptsize);
        __os_free(up, upsize);
        return (NULL);
}
#endif /* HAVE_GETCWD */

---