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incubator-nuttx/fs/vfs/fs_stat.c

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/****************************************************************************
* fs/vfs/fs_stat.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <string.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include "inode/inode.h"
#include <nuttx/mtd/mtd.h>
#include <nuttx/fs/ioctl.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define RESET_BUF(b) memset((b), 0, sizeof(struct stat));
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int stat_recursive(FAR const char *path,
FAR struct stat *buf, int resolve);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: stat_recursive
*
* Input Parameters:
* path - The inode of interest
* buf - The caller-provided location in which to return information
* about the inode.
* resolve - Whether to resolve the symbolic link:
* 0: Don't resolve the symbolic line
* 1: Resolve the symbolic link
* >=2: The recursive count in the resolving process
*
* Returned Value:
* Zero on success; < 0 on failure:
*
* 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.
*
****************************************************************************/
static int stat_recursive(FAR const char *path,
FAR struct stat *buf, int resolve)
{
struct inode_search_s desc;
FAR struct inode *inode;
int ret;
/* Get an inode for this path */
SETUP_SEARCH(&desc, path, true);
ret = inode_find(&desc);
if (ret < 0)
{
/* This name does not refer to an inode in the pseudo file system and
* there is no mountpoint that includes in this path.
*/
goto errout_with_search;
}
/* Get the search results */
inode = desc.node;
DEBUGASSERT(inode != NULL);
/* 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, desc.relpath, buf);
}
else
{
ret = -ENOSYS;
}
}
else
#endif
{
/* The node is part of the root pseudo file system. This path may
* recurse if soft links are supported in the pseudo file system.
*/
ret = inode_stat(inode, buf, resolve);
}
inode_release(inode);
errout_with_search:
RELEASE_SEARCH(&desc);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nx_stat
*
* Description:
* nx_stat() is similar to the standard 'stat' interface except that is
* not a cancellation point and it does not modify the errno variable.
*
* nx_stat() is an internal NuttX interface and should not be called from
* applications.
*
* Returned Value:
* Zero is returned on success; a negated value is returned on any failure.
*
****************************************************************************/
int nx_stat(FAR const char *path, FAR struct stat *buf, int resolve)
{
/* Sanity checks */
if (path == NULL || buf == NULL)
{
return -EFAULT;
}
if (*path == '\0')
{
return -ENOENT;
}
/* The perform the stat() operation on the path. This is potentially
* recursive if soft link support is enabled.
*/
return stat_recursive(path, buf, resolve);
}
/****************************************************************************
* 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)
{
int ret;
ret = nx_stat(path, buf, 1);
if (ret < 0)
{
set_errno(-ret);
ret = ERROR;
}
return ret;
}
int lstat(FAR const char *path, FAR struct stat *buf)
{
int ret;
ret = nx_stat(path, buf, 0);
if (ret < 0)
{
set_errno(-ret);
ret = ERROR;
}
return ret;
}
/****************************************************************************
* Name: inode_stat
*
* Description:
* The inode_stat() function will obtain information about an 'inode' in
* the pseudo file system and write it to the area pointed to by 'buf'.
*
* The 'buf' argument is a pointer to a stat structure, as defined in
* <sys/stat.h>, into which information is placed concerning the file.
*
* Input Parameters:
* inode - The inode of interest
* buf - The caller-provided location in which to return information
* about the inode.
* resolve - Whether to resolve the symbolic link:
* 0: Don't resolve the symbolic line
* 1: Resolve the symbolic link
* >=2: The recursive count in the resolving process
*
* Returned Value:
* Zero (OK) returned on success. Otherwise, a negated errno value is
* returned to indicate the nature of the failure.
*
****************************************************************************/
int inode_stat(FAR struct inode *inode, FAR struct stat *buf, int resolve)
{
DEBUGASSERT(inode != NULL && buf != NULL);
/* Most of the stat entries just do not apply */
RESET_BUF(buf);
/* Handle "special" nodes */
#if defined(CONFIG_FS_NAMED_SEMAPHORES)
/* Check for a named semaphore */
if (INODE_IS_NAMEDSEM(inode))
{
buf->st_mode = S_IFSEM;
}
else
#endif
#if !defined(CONFIG_DISABLE_MQUEUE) || !defined(CONFIG_DISABLE_MQUEUE_SYSV)
/* Check for a message queue */
if (INODE_IS_MQUEUE(inode))
{
buf->st_mode = S_IFMQ;
}
else
#endif
#if defined(CONFIG_FS_SHM)
/* Check for shared memory */
if (INODE_IS_SHM(inode))
{
buf->st_mode = S_IFSHM;
}
else
#endif
#if defined(CONFIG_MTD)
/* Check for an MTD driver */
if (INODE_IS_MTD(inode))
{
struct mtd_geometry_s mtdgeo;
buf->st_mode = S_IFMTD;
buf->st_mode |= S_IROTH | S_IRGRP | S_IRUSR;
buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
if (inode->u.i_mtd != NULL &&
MTD_IOCTL(inode->u.i_mtd, MTDIOC_GEOMETRY,
(unsigned long)((uintptr_t)&mtdgeo)) >= 0)
{
buf->st_size = mtdgeo.neraseblocks * mtdgeo.erasesize;
}
}
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))
{
if (resolve)
{
int ret;
/* Increment the link counter. This is necessary to avoid
* infinite recursion if loops are encountered in the
* traversal. If we encounter more SYMLOOP_MAX symbolic links
* at any time during the traversal, error out.
*
* NOTE: That inode_search() will automatically skip over
* consecutive, intermediate symbolic links. Those numbers
* will not be included in the total.
*/
if (resolve > SYMLOOP_MAX)
{
return -ELOOP;
}
/* stat() the target of the soft link. */
ret = stat_recursive(inode->u.i_link, buf, ++resolve);
/* If stat() fails, then there is a problem with the target of
* the symbolic link, but not with the symbolic link itself.
* We should still report success, just with less information.
*/
if (ret < 0)
{
RESET_BUF(buf);
}
return ret;
}
else
{
/* Make sure the caller knows that this is a symbolic link. */
buf->st_mode = S_IRWXO | S_IRWXG | S_IRWXU | S_IFLNK;
}
}
else
#endif
/* Handle "normal inodes */
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 */
/* Check for a mountpoint and a pseudo dir */
if (INODE_IS_MOUNTPT(inode) || INODE_IS_PSEUDODIR(inode))
{
buf->st_mode |= S_IFDIR;
}
/* Check for a block driver */
else if (INODE_IS_BLOCK(inode))
{
/* What is if also has child inodes? */
buf->st_mode |= S_IFBLK;
#ifndef CONFIG_DISABLE_MOUNTPOINT
if ((inode->u.i_bops != NULL) &&
(inode->u.i_bops->geometry != NULL))
{
struct geometry geo;
if (inode->u.i_bops->geometry(inode, &geo) >= 0 &&
geo.geo_available)
{
buf->st_size = geo.geo_nsectors * geo.geo_sectorsize;
}
}
#endif
}
/* Otherwise, the node must refer to a character driver */
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;
}
#ifdef CONFIG_PSEUDOFS_ATTRIBUTES
buf->st_mode |= inode->i_mode;
buf->st_uid = inode->i_owner;
buf->st_gid = inode->i_group;
buf->st_atim = inode->i_atime;
buf->st_mtim = inode->i_mtime;
buf->st_ctim = inode->i_ctime;
#endif
buf->st_ino = inode->i_ino;
return OK;
}
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