398 lines
9.7 KiB
C
398 lines
9.7 KiB
C
/* $NetBSD: getcwd.c,v 1.10 1998/02/03 18:23:44 perry Exp $ */
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/*
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* Copyright (c) 1989, 1991, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Jan-Simon Pendry.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95";
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#else
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__RCSID("$NetBSD: getcwd.c,v 1.10 1998/02/03 18:23:44 perry Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.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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#ifdef __weak_alias
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__weak_alias(getcwd,_getcwd);
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__weak_alias(realpath,_realpath);
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#endif
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static char *getcwd_physical __P((char *, size_t));
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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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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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char *pwd;
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size_t pwdlen;
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dev_t dev;
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ino_t ino;
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struct stat s;
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/* Check $PWD -- if it's right, it's fast. */
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if ((pwd = getenv("PWD")) != NULL && pwd[0] == '/' && !stat(pwd, &s)) {
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dev = s.st_dev;
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ino = s.st_ino;
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if (!stat(".", &s) && dev == s.st_dev && ino == s.st_ino) {
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pwdlen = strlen(pwd);
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if (size != 0) {
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if (pwdlen + 1 > size) {
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errno = ERANGE;
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return (NULL);
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}
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} else if ((pt = malloc(pwdlen + 1)) == NULL)
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return (NULL);
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memmove(pt, pwd, pwdlen);
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pt[pwdlen] = '\0';
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return (pt);
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}
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}
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return (getcwd_physical(pt, size));
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}
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/*
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* char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
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*
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* Find the real name of path, by removing all ".", ".." and symlink
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* components. Returns (resolved) on success, or (NULL) on failure,
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* in which case the path which caused trouble is left in (resolved).
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*/
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char *
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realpath(path, resolved)
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const char *path;
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char *resolved;
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{
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struct stat sb;
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int fd, n, rootd, serrno;
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char *p, *q, wbuf[MAXPATHLEN];
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/* Save the starting point. */
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if ((fd = open(".", O_RDONLY)) < 0) {
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(void)strcpy(resolved, ".");
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return (NULL);
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}
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/*
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* Find the dirname and basename from the path to be resolved.
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* Change directory to the dirname component.
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* lstat the basename part.
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* if it is a symlink, read in the value and loop.
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* if it is a directory, then change to that directory.
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* get the current directory name and append the basename.
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*/
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(void)strncpy(resolved, path, MAXPATHLEN - 1);
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resolved[MAXPATHLEN - 1] = '\0';
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loop:
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q = strrchr(resolved, '/');
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if (q != NULL) {
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p = q + 1;
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if (q == resolved)
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q = "/";
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else {
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do {
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--q;
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} while (q > resolved && *q == '/');
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q[1] = '\0';
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q = resolved;
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}
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if (chdir(q) < 0)
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goto err1;
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} else
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p = resolved;
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/* Deal with the last component. */
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if (lstat(p, &sb) == 0) {
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if (S_ISLNK(sb.st_mode)) {
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n = readlink(p, resolved, MAXPATHLEN);
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if (n < 0)
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goto err1;
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resolved[n] = '\0';
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goto loop;
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}
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if (S_ISDIR(sb.st_mode)) {
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if (chdir(p) < 0)
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goto err1;
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p = "";
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}
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}
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/*
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* Save the last component name and get the full pathname of
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* the current directory.
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*/
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(void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
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/*
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* Call the inernal internal version of getcwd which
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* does a physical search rather than using the $PWD short-cut
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*/
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if (getcwd_physical(resolved, MAXPATHLEN) == 0)
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goto err1;
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/*
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* Join the two strings together, ensuring that the right thing
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* happens if the last component is empty, or the dirname is root.
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*/
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if (resolved[0] == '/' && resolved[1] == '\0')
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rootd = 1;
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else
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rootd = 0;
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if (*wbuf) {
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if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
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errno = ENAMETOOLONG;
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goto err1;
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}
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if (rootd == 0)
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(void)strcat(resolved, "/"); /* XXX: strcat is safe */
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(void)strcat(resolved, wbuf); /* XXX: strcat is safe */
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}
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/* Go back to where we came from. */
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if (fchdir(fd) < 0) {
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serrno = errno;
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goto err2;
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}
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/* It's okay if the close fails, what's an fd more or less? */
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(void)close(fd);
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return (resolved);
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err1: serrno = errno;
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(void)fchdir(fd);
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err2: (void)close(fd);
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errno = serrno;
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return (NULL);
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}
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static char *
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getcwd_physical(pt, size)
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char *pt;
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size_t size;
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{
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struct dirent *dp;
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DIR *dir;
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dev_t dev;
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ino_t ino;
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int first;
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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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ptsize = 0;
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if (!size) {
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errno = EINVAL;
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return (NULL);
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}
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ept = pt + size;
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} else {
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if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
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return (NULL);
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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 = malloc(upsize = 1024 - 4)) == NULL)
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goto err;
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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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/* Stat the current level. */
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if (lstat(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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*--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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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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if ((up = realloc(up, upsize *= 2)) == NULL)
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goto err;
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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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for (;;) {
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if (!(dp = readdir(dir)))
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goto notfound;
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if (dp->d_fileno == ino)
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break;
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}
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} else
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for (;;) {
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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, dp->d_namlen + 1);
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/* Save the first error for later. */
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if (lstat(up, &s)) {
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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 <= dp->d_namlen + (first ? 1 : 2)) {
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size_t len, off;
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if (!ptsize) {
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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 = realloc(pt, ptsize *= 2)) == NULL)
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goto err;
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bpt = pt + off;
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ept = pt + ptsize;
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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 -= dp->d_namlen;
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bcopy(dp->d_name, bpt, dp->d_namlen);
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(void)closedir(dir);
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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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free(up);
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return (NULL);
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}
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