getcwd.c
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上传日期:2022-05-23
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文件大小:7k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1996-2002
- * 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.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: getcwd.c,v 11.13 2002/02/28 21:27:18 ubell Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #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 <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <unistd.h>
- #endif
- #include "db_int.h"
- #define ISDOT(dp)
- (dp->d_name[0] == '.' && (dp->d_name[1] == ' ' ||
- (dp->d_name[1] == '.' && dp->d_name[2] == ' ')))
- #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(NULL, ptsize = 1024 - 4, &pt)) != 0) {
- __os_set_errno(ret);
- return (NULL);
- }
- ept = pt + ptsize;
- }
- bpt = ept - 1;
- *bpt = ' ';
- /*
- * 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(NULL, upsize = 1024 - 4, &up)) != 0)
- goto err;
- eup = up + 1024;
- bup = up;
- up[0] = '.';
- up[1] = ' ';
- /* 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(NULL, up);
- 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(NULL, upsize *= 2, &up) != 0)
- goto err;
- bup = up;
- eup = up + upsize;
- }
- *bup++ = '.';
- *bup++ = '.';
- *bup = ' ';
- /* 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(NULL, ptsize *= 2, &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 = ' ';
- }
- 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_ret_zero() == 0)
- __os_set_errno(save_errno == 0 ? ENOENT : save_errno);
- /* FALLTHROUGH */
- err:
- if (ptsize)
- __os_free(NULL, pt);
- __os_free(NULL, up);
- return (NULL);
- }