newlib-cygwin/newlib/libc/unix/getcwd.c

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2000-02-18 03:39:52 +08:00
/*
* Copyright (c) 1989, 1991 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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 sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) 2/24/91";
#endif /* LIBC_SCCS and not lint */
#include <sys/stat.h>
#include <errno.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <reent.h>
#include <_syslist.h>
#define bcopy(a,b,c) memmove (b,a,c)
#define ISDOT(dp) \
(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
(dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
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#ifndef _REENT_ONLY
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 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 (char *) NULL;
}
ept = pt + size;
}
else
{
if (!(pt = (char *) malloc (ptsize = 1024 - 4)))
{
return (char *) 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 (!(up = (char *) malloc (upsize = 1024 - 4)))
{
goto err;
}
eup = up + MAXPATHLEN;
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 (stat (up, &s))
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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.
*/
(void) bcopy (bpt, pt, 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 NULL.
*/
if (bup + 3 + MAXNAMLEN + 1 >= eup)
{
if (!(up = (char *) realloc (up, upsize *= 2)))
{
goto err;
}
bup = up;
eup = up + upsize;
}
*bup++ = '.';
*bup++ = '.';
*bup = '\0';
/* Open and stat parent directory. */
if (!(dir = opendir (up)) || fstat (__dirfd (dir), &s))
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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)))
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goto notfound;
if (dp->d_ino == ino)
break;
}
}
else
for (;;)
{
if (!(dp = readdir (dir)))
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goto notfound;
if (ISDOT (dp))
continue;
bcopy (dp->d_name, bup, strlen (dp->d_name) + 1);
/* Save the first error for later. */
if (stat (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 <= strlen (dp->d_name) + (first ? 1 : 2))
{
size_t len, off;
if (!ptsize)
{
errno = ERANGE;
goto err;
}
off = bpt - pt;
len = ept - bpt;
if (!(pt = (char *) realloc (pt, ptsize *= 2)))
{
goto err;
}
bpt = pt + off;
ept = pt + ptsize;
(void) bcopy (bpt, ept - len, len);
bpt = ept - len;
}
if (!first)
*--bpt = '/';
bpt -= strlen (dp->d_name);
bcopy (dp->d_name, bpt, strlen (dp->d_name));
(void) closedir (dir);
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/* 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);
return (char *) NULL;
}
#endif /* _REENT_ONLY */