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nuttx/fs/vfs/fs_stat.c

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/****************************************************************************
* fs/vfs/fs_stat.c
*
* Copyright (C) 2007-2009, 2012, 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 NuttX 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/stat.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include "inode/inode.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: statpseudo
****************************************************************************/
static inline int statpseudo(FAR struct inode *inode, FAR struct stat *buf)
{
/* Most of the stat entries just do not apply */
memset(buf, 0, sizeof(struct stat));
if (INODE_IS_SPECIAL(inode))
{
#if defined(CONFIG_FS_NAMED_SEMAPHORES)
if (INODE_IS_NAMEDSEM(inode))
{
buf->st_mode = S_IFSEM;
}
else
#endif
#if !defined(CONFIG_DISABLE_MQUEUE)
if (INODE_IS_MQUEUE(inode))
{
buf->st_mode = S_IFMQ;
}
else
#endif
#if defined(CONFIG_FS_SHM)
if (INODE_IS_SHM(inode)) */
{
buf->st_mode = S_IFSHM;
}
else
#endif
#ifdef CONFIG_PSEUDOFS_SOFTLINKS
/* Handle softlinks differently. Just call stat() recursively on the
* target of the softlink.
*
* REVISIT: This has the possibility of an infinite loop!
*/
if (INODE_IS_SOFTLINK(inode))
{
int ret;
/* stat() the target of the soft link.
*
* Note: We don't really handle links to links nicely. I suppose
* that we should repetitively deference the symbolic link inodes
* until we discover the true target link?
*/
ret = stat((FAR const char *)inode->u.i_link, buf);
/* If stat() fails, then there is a probleml with target of the
* symbolic link, but not with the symbolic link itself. We should
* still report success, just with less information.
*/
if (ret < 0)
{
memset(buf, 0, sizeof(struct stat));
}
/* And make sure that the caller knows that this really a symbolic link. */
buf->st_mode |= S_IFLNK;
}
else
#endif
{
}
}
else if (inode->u.i_ops != NULL)
{
/* Determine read/write privileges based on the existence of read
* and write methods.
*/
if (inode->u.i_ops->read)
{
buf->st_mode = S_IROTH | S_IRGRP | S_IRUSR;
}
if (inode->u.i_ops->write)
{
buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
}
/* Determine the type of the inode */
if (INODE_IS_MOUNTPT(inode))
{
buf->st_mode |= S_IFDIR;
}
else if (INODE_IS_BLOCK(inode))
{
/* What is if also has child inodes? */
buf->st_mode |= S_IFBLK;
}
else /* if (INODE_IS_DRIVER(inode)) */
{
/* What is it if it also has child inodes? */
buf->st_mode |= S_IFCHR;
}
}
else
{
/* If it has no operations, then it must just be a intermediate
* node in the inode tree. It is something like a directory.
* We'll say that all pseudo-directories are read-able but not
* write-able.
*/
buf->st_mode |= S_IFDIR | S_IROTH | S_IRGRP | S_IRUSR;
}
return OK;
}
/****************************************************************************
* Name: statroot
****************************************************************************/
static inline int statroot(FAR struct stat *buf)
{
/* There is no inode associated with the fake root directory */
memset(buf, 0, sizeof(struct stat));
buf->st_mode = S_IFDIR | S_IROTH | S_IRGRP | S_IRUSR;
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: stat
*
* Returned Value:
* Zero on success; -1 on failure with errno set:
*
* EACCES Search permission is denied for one of the directories in the
* path prefix of path.
* EFAULT Bad address.
* ENOENT A component of the path path does not exist, or the path is an
* empty string.
* ENOMEM Out of memory
* ENOTDIR A component of the path is not a directory.
*
****************************************************************************/
int stat(FAR const char *path, FAR struct stat *buf)
{
FAR struct inode *inode;
const char *relpath = NULL;
int ret = OK;
/* Sanity checks */
if (!path || !buf)
{
ret = EFAULT;
goto errout;
}
if (!path[0])
{
ret = ENOENT;
goto errout;
}
/* Check for the fake root directory (which has no inode) */
if (strcmp(path, "/") == 0)
{
return statroot(buf);
}
/* Get an inode for this file */
inode = inode_find_nofollow(path, &relpath);
if (!inode)
{
/* This name does not refer to a psudeo-inode and there is no
* mountpoint that includes in this path.
*/
ret = ENOENT;
goto errout;
}
/* The way we handle the stat depends on the type of inode that we
* are dealing with.
*/
#ifndef CONFIG_DISABLE_MOUNTPOINT
if (INODE_IS_MOUNTPT(inode))
{
/* The node is a file system mointpoint. Verify that the mountpoint
* supports the stat() method
*/
if (inode->u.i_mops && inode->u.i_mops->stat)
{
/* Perform the stat() operation */
ret = inode->u.i_mops->stat(inode, relpath, buf);
}
}
else
#endif
{
/* The node is part of the root pseudo file system */
ret = statpseudo(inode, buf);
}
/* Check if the stat operation was successful */
if (ret < 0)
{
ret = -ret;
goto errout_with_inode;
}
/* Successfully stat'ed the file */
inode_release(inode);
return OK;
/* Failure conditions always set the errno appropriately */
errout_with_inode:
inode_release(inode);
errout:
set_errno(ret);
return ERROR;
}
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