268 lines
6.5 KiB
C
268 lines
6.5 KiB
C
#ifndef _NO_GETCWD
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/*
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* Copyright (c) 1989, 1991 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) 2/24/91";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <dirent.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <reent.h>
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#include <_syslist.h>
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#define bcopy(a,b,c) memmove (b,a,c)
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#define ISDOT(dp) \
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(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
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(dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
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#ifndef _REENT_ONLY
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char *
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getcwd (pt, size)
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char *pt;
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size_t size;
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{
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register struct dirent *dp;
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register DIR *dir = NULL;
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register dev_t dev;
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register ino_t ino;
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register int first;
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register char *bpt, *bup;
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struct stat s;
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dev_t root_dev;
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ino_t root_ino;
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size_t ptsize, upsize;
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int save_errno;
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char *ept, *eup, *up;
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/*
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* If no buffer specified by the user, allocate one as necessary.
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* If a buffer is specified, the size has to be non-zero. The path
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* is built from the end of the buffer backwards.
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*/
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if (pt)
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{
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ptsize = 0;
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if (!size)
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{
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errno = EINVAL;
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return (char *) NULL;
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}
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ept = pt + size;
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}
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else
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{
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if (!(pt = (char *) malloc (ptsize = 1024 - 4)))
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{
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return (char *) NULL;
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}
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ept = pt + ptsize;
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}
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bpt = ept - 1;
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*bpt = '\0';
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/*
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* Allocate bytes (1024 - malloc space) for the string of "../"'s.
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* Should always be enough (it's 340 levels). If it's not, allocate
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* as necessary. Special * case the first stat, it's ".", not "..".
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*/
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if (!(up = (char *) malloc (upsize = 1024 - 4)))
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{
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goto err;
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}
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eup = up + MAXPATHLEN;
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bup = up;
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up[0] = '.';
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up[1] = '\0';
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/* Save root values, so know when to stop. */
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if (stat ("/", &s))
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goto err;
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root_dev = s.st_dev;
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root_ino = s.st_ino;
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errno = 0; /* XXX readdir has no error return. */
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for (first = 1;; first = 0)
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{
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/* Stat the current level. */
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if (stat (up, &s))
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goto err;
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/* Save current node values. */
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ino = s.st_ino;
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dev = s.st_dev;
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/* Check for reaching root. */
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if (root_dev == dev && root_ino == ino)
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{
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*--bpt = '/';
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/*
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* It's unclear that it's a requirement to copy the
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* path to the beginning of the buffer, but it's always
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* been that way and stuff would probably break.
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*/
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(void) bcopy (bpt, pt, ept - bpt);
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free (up);
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return pt;
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}
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/*
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* Build pointer to the parent directory, allocating memory
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* as necessary. Max length is 3 for "../", the largest
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* possible component name, plus a trailing NULL.
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*/
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if (bup + 3 + MAXNAMLEN + 1 >= eup)
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{
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if (!(up = (char *) realloc (up, upsize *= 2)))
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{
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goto err;
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}
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bup = up;
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eup = up + upsize;
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}
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*bup++ = '.';
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*bup++ = '.';
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*bup = '\0';
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/* Open and stat parent directory. */
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if (!(dir = opendir (up)) || fstat (__dirfd (dir), &s))
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goto err;
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/* Add trailing slash for next directory. */
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*bup++ = '/';
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/*
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* If it's a mount point, have to stat each element because
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* the inode number in the directory is for the entry in the
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* parent directory, not the inode number of the mounted file.
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*/
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save_errno = 0;
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if (s.st_dev == dev)
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{
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for (;;)
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{
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if (!(dp = readdir (dir)))
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goto notfound;
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if (dp->d_ino == ino)
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break;
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}
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}
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else
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for (;;)
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{
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if (!(dp = readdir (dir)))
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goto notfound;
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if (ISDOT (dp))
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continue;
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bcopy (dp->d_name, bup, strlen (dp->d_name) + 1);
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/* Save the first error for later. */
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if (stat (up, &s))
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{
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if (!save_errno)
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save_errno = errno;
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errno = 0;
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continue;
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}
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if (s.st_dev == dev && s.st_ino == ino)
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break;
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}
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/*
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* Check for length of the current name, preceding slash,
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* leading slash.
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*/
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if (bpt - pt <= strlen (dp->d_name) + (first ? 1 : 2))
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{
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size_t len, off;
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if (!ptsize)
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{
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errno = ERANGE;
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goto err;
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}
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off = bpt - pt;
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len = ept - bpt;
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if (!(pt = (char *) realloc (pt, ptsize *= 2)))
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{
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goto err;
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}
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bpt = pt + off;
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ept = pt + ptsize;
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(void) bcopy (bpt, ept - len, len);
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bpt = ept - len;
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}
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if (!first)
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*--bpt = '/';
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bpt -= strlen (dp->d_name);
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bcopy (dp->d_name, bpt, strlen (dp->d_name));
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(void) closedir (dir);
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dir = NULL;
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/* Truncate any file name. */
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*bup = '\0';
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}
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notfound:
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/*
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* If readdir set errno, use it, not any saved error; otherwise,
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* didn't find the current directory in its parent directory, set
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* errno to ENOENT.
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*/
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if (!errno)
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errno = save_errno ? save_errno : ENOENT;
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/* FALLTHROUGH */
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err:
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if (ptsize)
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free (pt);
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if (dir)
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(void) closedir (dir);
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free (up);
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return (char *) NULL;
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}
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#endif /* _REENT_ONLY */
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#endif /* !_NO_GETCWD */
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