nuttx/fs/vfs/fs_fstat.c
Gregory Nutt 1c002e1049 fs/vfs/fs_fstat: Correct fstat() for proxied block and MTD drivers.
Block and MTD drivers may be opened and managed as though they were character drivers.  But this is really sleight of hand; there is a hidden character driver proxy that mediates the interface to the block and MTD drivers in this case.

fstat(), however, did not account for this.  It would report the characteristics of the proxy character driver, not of the underlying block or MTD driver.

This change corrects that.  fstat now checks if the character driver is such a proxy and, if so, reports the characteristics of the underlying block or MTD driver, not the proxy character driver.
2020-05-28 17:34:09 +01:00

286 lines
8.1 KiB
C

/****************************************************************************
* fs/vfs/fs_fstat.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 <unistd.h>
#include <sched.h>
#include <errno.h>
#include <nuttx/fs/fs.h>
#include <nuttx/mtd/mtd.h>
#include "inode/inode.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: proxy_fstat
*
* Description:
* Check for special cases where the character driver is really just a
* proxy for the real, underlying MTD or block driver.
*
* NOTE: This must be done here rather than in the the common
* inode_stat() function because the filep reference must be available
* in order to call the character driver ioctl method.
*
* Input Parameters:
* filep - File structure instance
* inode - The inode associated with the file descriptor
* buf - The caller provide location in which to return information
* about the open file.
*
* Returned Value:
* Upon successful completion, 0 is returned. Otherwise, a negated errno
* value is returned.
*
****************************************************************************/
static int proxy_fstat(FAR struct file *filep, FAR struct inode *inode,
FAR struct stat *buf)
{
#ifdef CONFIG_MTD
struct mtd_geometry_s mtdgeo;
#endif
#ifndef CONFIG_DISABLE_MOUNTPOINT
struct geometry blkgeo;
#endif
int ret = -ENOENT;
/* Check if this is a valid character driver */
if (INODE_IS_DRIVER(inode) &&
inode->u.i_ops != NULL &&
inode->u.i_ops->ioctl != NULL)
{
#ifdef CONFIG_MTD
/* Check if this is a proxy for an MTD driver. In this case, both the
* MTDIOC_GEOMETRY ioctl and the BIOC_GEOMTRY will be supported by
* character driver.
*/
if (inode->u.i_ops->ioctl(filep, MTDIOC_GEOMETRY,
(unsigned long)((uintptr_t)&mtdgeo)) >= 0)
{
memset(buf, 0, sizeof(struct stat));
buf->st_mode = S_IFMTD;
buf->st_mode |= S_IROTH | S_IRGRP | S_IRUSR;
buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
buf->st_size = mtdgeo.neraseblocks * mtdgeo.erasesize;
ret = OK;
}
#ifndef CONFIG_DISABLE_MOUNTPOINT
else
#endif
#endif
#ifndef CONFIG_DISABLE_MOUNTPOINT
/* Check if this is a proxy for a block driver. In this case, only
* the BIOC_GEOMETRY ioctl will be supported.
*/
if (inode->u.i_ops->ioctl(filep, BIOC_GEOMETRY,
(unsigned long)((uintptr_t)&blkgeo)) >= 0)
{
memset(buf, 0, sizeof(struct stat));
buf->st_mode = S_IFBLK;
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;
}
if (blkgeo.geo_available)
{
buf->st_size = blkgeo.geo_nsectors * blkgeo.geo_sectorsize;
}
ret = OK;
}
#endif
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_fstat
*
* Description:
* file_fstat() is an internal OS interface. It is functionally similar
* to the standard fstat() interface except:
*
* - It does not modify the errno variable,
* - It is not a cancellation point,
* - It does not handle socket descriptors, and
* - It accepts a file structure instance instead of file descriptor.
*
* Input Parameters:
* filep - File structure instance
* buf - The caller provide location in which to return information
* about the open file.
*
* Returned Value:
* Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
* returned and errno set to indicate the error.
*
****************************************************************************/
int file_fstat(FAR struct file *filep, FAR struct stat *buf)
{
FAR struct inode *inode;
int ret;
DEBUGASSERT(filep != NULL);
/* Get the inode from the file structure */
inode = filep->f_inode;
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 inode is a file system mountpoint. Verify that the mountpoint
* supports the fstat() method
*/
ret = -ENOSYS;
if (inode->u.i_mops && inode->u.i_mops->fstat)
{
/* Perform the fstat() operation */
ret = inode->u.i_mops->fstat(filep, buf);
}
}
else
#endif
{
/* Check if the inode is a proxy for a block or MTD driver */
ret = proxy_fstat(filep, inode, buf);
if (ret < 0)
{
/* The inode is part of the root pseudo file system. */
ret = inode_stat(inode, buf);
}
}
return ret;
}
/****************************************************************************
* Name: fstat
*
* Description:
* The fstat() function will obtain information about an open file
* associated with the file descriptor 'fd', and will 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:
* fd - The file descriptor associated with the open file of interest
* buf - The caller provide location in which to return information about
* the open file.
*
* Returned Value:
* Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
* returned and errno set to indicate the error.
*
****************************************************************************/
int fstat(int fd, FAR struct stat *buf)
{
FAR struct file *filep;
int ret;
/* Did we get a valid file descriptor? */
if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
{
#ifdef CONFIG_NET
/* Let the networking logic handle the fstat() */
ret = net_fstat(fd, buf);
if (ret < 0)
{
goto errout;
}
return OK;
#else
/* No networking... it is just a bad descriptor */
ret = -EBADF;
goto errout;
#endif
}
/* The descriptor is in a valid range for a file descriptor... do the
* fstat. First, get the file structure. Note that on failure,
* fs_getfilep() will set the errno variable.
*/
ret = fs_getfilep(fd, &filep);
if (ret < 0)
{
goto errout;
}
/* Perform the fstat operation */
ret = file_fstat(filep, buf);
/* Check if the fstat operation was successful */
if (ret >= 0)
{
/* Successfully fstat'ed the file */
return OK;
}
errout:
set_errno(-ret);
return ERROR;
}