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/*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: getcwd.c,v 1.12 2005/03/25 15:38:47 otto Exp $";
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define ISDOT(dp) \
(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
(dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
char *
getcwd(char *pt, size_t size)
{
struct dirent *dp;
DIR *dir = NULL;
dev_t dev;
ino_t ino;
int first;
char *bpt, *bup;
struct stat s;
dev_t root_dev;
ino_t root_ino;
size_t ptsize, upsize;
int 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) {
errno = EINVAL;
return (NULL);
}
ept = pt + size;
} else {
if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL)
return (NULL);
ept = pt + ptsize;
}
bpt = ept - 1;
*bpt = '\0';
/*
* Allocate bytes 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 ((up = malloc(upsize = MAXPATHLEN)) == NULL)
goto err;
eup = up + upsize;
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;
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 = '/';
/*
* 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.
*/
memmove(pt, bpt, ept - bpt);
free(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 NUL.
*/
if (bup + 3 + MAXNAMLEN + 1 >= eup) {
char *nup;
if ((nup = realloc(up, upsize *= 2)) == NULL)
goto err;
bup = nup + (bup - up);
up = nup;
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++ = '/';
/*
* 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;
memcpy(bup, dp->d_name, dp->d_namlen + 1);
/* Save the first error for later. */
if (lstat(up, &s)) {
if (!save_errno)
save_errno = errno;
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;
char *npt;
if (!ptsize) {
errno = ERANGE;
goto err;
}
len = ept - bpt;
if ((npt = realloc(pt, ptsize *= 2)) == NULL)
goto err;
bpt = npt + (bpt - pt);
pt = npt;
ept = pt + ptsize;
memmove(ept - len, bpt, len);
bpt = ept - len;
}
if (!first)
*--bpt = '/';
bpt -= dp->d_namlen;
memcpy(bpt, dp->d_name, 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 (!errno)
errno = save_errno ? save_errno : ENOENT;
/* FALLTHROUGH */
err:
if (ptsize)
free(pt);
free(up);
if (dir)
(void)closedir(dir);
return (NULL);
}
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