chdir.c

来自「lustre 1.6.5 source code」· C语言 代码 · 共 279 行

/*
 *    This Cplant(TM) source code is the property of Sandia National
 *    Laboratories.
 *
 *    This Cplant(TM) source code is copyrighted by Sandia National
 *    Laboratories.
 *
 *    The redistribution of this Cplant(TM) source code is subject to the
 *    terms of the GNU Lesser General Public License
 *    (see cit/LGPL or http://www.gnu.org/licenses/lgpl.html)
 *
 *    Cplant(TM) Copyright 1998-2006 Sandia Corporation. 
 *    Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 *    license for use of this work by or on behalf of the US Government.
 *    Export of this program may require a license from the United States
 *    Government.
 */

/*
 * #############################################################################
 * #
 * #     This Cplant(TM) source code is the property of Sandia National
 * #     Laboratories.
 * #
 * #     This Cplant(TM) source code is copyrighted by Sandia National
 * #     Laboratories.
 * #
 * #     The redistribution of this Cplant(TM) source code is subject to the
 * #     terms of the GNU Lesser General Public License
 * #     (see cit/LGPL or http://www.gnu.org/licenses/lgpl.html)
 * #
 * #     Cplant(TM) Copyright 1998-2003 Sandia Corporation. 
 * #     Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 * #     license for use of this work by or on behalf of the US Government.
 * #     Export of this program may require a license from the United States
 * #     Government.
 * #
 * #############################################################################
 */

/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Questions or comments about this library should be sent to:
 *
 * Lee Ward
 * Sandia National Laboratories, New Mexico
 * P.O. Box 5800
 * Albuquerque, NM 87185-1110
 *
 * [e-mail]
 */

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <assert.h>
#include <sys/queue.h>

#include "sysio.h"
#include "inode.h"
#include "mount.h"
#include "file.h"
#include "sysio-symbols.h"

#ifdef DEFER_INIT_CWD
const char *_sysio_init_cwd = NULL;
#endif

struct pnode *_sysio_cwd = NULL;

/*
 * Change to directory specified by the given pnode.
 */
int
_sysio_p_chdir(struct pnode *pno)
{
	int	err;

	/*
	 * Revalidate the pnode, and ensure it's an accessable directory
	 */
	err = _sysio_p_validate(pno, NULL, NULL);
	if (err)
		return err;
	if (!(pno->p_base->pb_ino &&
	      S_ISDIR(pno->p_base->pb_ino->i_stbuf.st_mode)))
		return -ENOTDIR;
	if ((err = _sysio_permitted(pno, X_OK)) != 0)
		return err;

	/*
	 * Release old if set.
	 */
        if (_sysio_cwd)
                P_RELE(_sysio_cwd);

	/*
	 * Finally, change to the new.
	 */
        _sysio_cwd = pno;

        return 0;
}

int
SYSIO_INTERFACE_NAME(chdir)(const char *path)
{
        int     err;
        struct pnode *pno;
	SYSIO_INTERFACE_DISPLAY_BLOCK;

	SYSIO_INTERFACE_ENTER;
        err = _sysio_namei(_sysio_cwd, path, 0, NULL, &pno);
        if (err)
		SYSIO_INTERFACE_RETURN(-1, err);

	err = _sysio_p_chdir(pno);
	if (err)
		P_RELE(pno);
	SYSIO_INTERFACE_RETURN(err ? -1 : 0, err);
}

#ifdef REDSTORM
#undef __chdir
sysio_sym_weak_alias(SYSIO_INTERFACE_NAME(chdir),
		     PREPEND(__, SYSIO_INTERFACE_NAME(chdir)))
#endif

/*
 * Return path tracked by the path ancestor chain.
 *
 * If the buf pointer is NULL, a buffer large enough to hold the path
 * is allocated from the heap.
 */

static int
_sysio_p_path(struct pnode *pno, char **buf, size_t size)
{
	struct pnode *cur;
	size_t	len;
	size_t	n;
	char	*cp;

	cur = pno;

	if (!size && buf && *buf)
		return -EINVAL;

	/*
	 * Walk up the tree to the root, summing the component name
	 * lengths and counting the vertices.
	 */
	len = 0;
	n = 0;
	do {
		/*
		 * If this is a covering path-node then the name should be
		 * the *covered* nodes name, not this one unless we are at
		 * the root of the name-space.
		 */
		while (pno == pno->p_mount->mnt_root && pno != pno->p_parent )
			pno = pno->p_mount->mnt_covers;

		/*
		 * Add length of this component to running sum and
		 * account for this vertex.
		 */
		assert((len >= pno->p_base->pb_name.len &&
			(size_t )~0 - pno->p_base->pb_name.len > len) ||
		       (size_t )~0 - len > pno->p_base->pb_name.len);
		len += pno->p_base->pb_name.len;
		n++;
		assert(n);
		pno = pno->p_parent;
	} while (pno != pno->p_parent);

	if (!*buf)
		size = len + n + 1;
	if (len >= size || n >= size - len)
		return -ERANGE;
	if (!*buf) {
		/*
		 * Allocate path buffer from the heap.
		 */
		*buf = malloc(size * sizeof(char));
		if (!*buf)
			return -ENOMEM;
	}

	/*
	 * Fill in the path buffer.
	 */
	pno = cur;
	cp = *buf + len + n;
	*cp = '\0';					/* NUL terminate */
	do {
		/*
		 * If this is a covering path-node then the name should be
		 * the *covered* nodes name, not this one unless we are at
		 * the root of the name-space.
		 */
		while (pno == pno->p_mount->mnt_root && pno != pno->p_parent )
			pno = pno->p_mount->mnt_covers;

		/*
		 * Add component and separator.
		 */
		cp -= pno->p_base->pb_name.len;
		(void )memcpy(cp, pno->p_base->pb_name.name,
			      pno->p_base->pb_name.len);

		*--cp = PATH_SEPARATOR;
		pno = pno->p_parent;
	} while (pno != pno->p_parent);

	return 0;
}

char *
SYSIO_INTERFACE_NAME(getcwd)(char *buf, size_t size)
{
	int	err;
	SYSIO_INTERFACE_DISPLAY_BLOCK;

	SYSIO_INTERFACE_ENTER;
#ifdef DEFER_INIT_CWD
	if (!_sysio_cwd) {
		struct pnode *pno;

		/*
		 * Can no longer defer initialization of the current working
		 * directory. Force namei to make it happen now.
		 */
	        if (_sysio_namei(NULL, ".", 0, NULL, &pno) != 0)
			abort();
		P_RELE(pno);
	}
#endif
	err = _sysio_p_path(_sysio_cwd, &buf, buf ? size : 0);
	SYSIO_INTERFACE_RETURN(err ? NULL : buf, err);
}

#ifdef __GLIBC__
#undef __getcwd
sysio_sym_weak_alias(SYSIO_INTERFACE_NAME(getcwd), 
		     PREPEND(__, SYSIO_INTERFACE_NAME(getcwd)))
#endif

#if defined(PATH_MAX) && !(defined(REDSTORM))
char    *
SYSIO_INTERFACE_NAME(getwd)(char *buf)
{

	if (!buf) {
		errno = EFAULT;
		return NULL;
	}

	return SYSIO_INTERFACE_NAME(getcwd)(buf, PATH_MAX);
}
#endif