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incubator-nuttx/fs/fs_mount.c

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/****************************************************************************
* fs/fs_mount.c
*
* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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/types.h>
#include <sys/mount.h>
#include <string.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/fs.h>
#include "fs_internal.h"
/* At least one filesystem must be defined, or this file will not compile.
* It may be desire-able to make filesystems dynamically registered at
* some time in the future, but at present, this file needs to know about
* every configured filesystem.
*/
#ifdef CONFIG_FS_READABLE
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
struct fsmap_t
{
const char *fs_filesystemtype;
const struct mountpt_operations *fs_mops;
};
/****************************************************************************
* Private Variables
****************************************************************************/
#ifdef CONFIG_FS_FAT
extern const struct mountpt_operations fat_operations;
#endif
#ifdef CONFIG_FS_ROMFS
extern const struct mountpt_operations romfs_operations;
#endif
static const struct fsmap_t g_fsmap[] =
{
#ifdef CONFIG_FS_FAT
{ "vfat", &fat_operations },
#endif
#ifdef CONFIG_FS_ROMFS
{ "romfs", &romfs_operations },
#endif
{ NULL, NULL },
};
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: mount_findfs
*
* Description:
* find the specified filesystem
*
****************************************************************************/
static FAR const struct mountpt_operations *mount_findfs(const char *filesystemtype )
{
const struct fsmap_t *fsmap;
for (fsmap = g_fsmap; fsmap->fs_filesystemtype; fsmap++)
{
if (strcmp(filesystemtype, fsmap->fs_filesystemtype) == 0)
{
return fsmap->fs_mops;
}
}
return NULL;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mount
*
* Description:
* mount() attaches the filesystem specified by the 'source' block device
* name into the root file system at the path specified by 'target.'
*
* Return:
* Zero is returned on success; -1 is returned on an error and errno is
* set appropriately:
*
* EACCES A component of a path was not searchable or mounting a read-only
* filesystem was attempted without giving the MS_RDONLY flag.
* EBUSY 'source' is already mounted.
* EFAULT One of the pointer arguments points outside the user address
* space.
* EINVAL 'source' had an invalid superblock.
* ENODEV 'filesystemtype' not configured
* ENOENT A pathname was empty or had a nonexistent component.
* ENOMEM Could not allocate a memory to copy filenames or data into.
* ENOTBLK 'source' is not a block device
*
****************************************************************************/
int mount(const char *source, const char *target,
const char *filesystemtype, unsigned long mountflags,
const void *data)
{
FAR struct inode *blkdrvr_inode;
FAR struct inode *mountpt_inode;
FAR const struct mountpt_operations *mops;
void *fshandle;
int errcode;
int status;
/* Verify required pointer arguments */
if (!source || !target || !filesystemtype)
{
errcode = EFAULT;
goto errout;
}
/* Find the specified filesystem */
mops = mount_findfs(filesystemtype);
if (!mops)
{
fdbg("Failed to find filsystem %s\n", filesystemtype);
errcode = ENODEV;
goto errout;
}
/* Find the inode of the block driver indentified by 'source' */
status = find_blockdriver(source, mountflags, &blkdrvr_inode);
if (status < 0)
{
fdbg("Failed to find block driver %s\n", source);
errcode = -status;
goto errout;
}
/* Insert a dummy node -- we need to hold the inode semaphore
* to do this because we will have a momentarily bad structure.
*/
inode_semtake();
mountpt_inode = inode_reserve(target);
if (!mountpt_inode)
{
/* inode_reserve can fail for a couple of reasons, but the most likely
* one is that the inode already exists.
*/
fdbg("Failed to reserve inode\n");
errcode = EBUSY;
goto errout_with_semaphore;
}
/* Bind the block driver to an instance of the file system. The file
* system returns a reference to some opaque, fs-dependent structure
* that encapsulates this binding.
*/
if (!mops->bind)
{
/* The filesystem does not support the bind operation ??? */
fdbg("Filesystem does not support bind\n");
errcode = EINVAL;
goto errout_with_mountpt;
}
/* Increment reference count for the reference we pass to the file system */
blkdrvr_inode->i_crefs++;
/* On failure, the bind method returns -errorcode */
status = mops->bind(blkdrvr_inode, data, &fshandle);
if (status != 0)
{
/* The inode is unhappy with the blkdrvr for some reason. Back out
* the count for the reference we failed to pass and exit with an
* error.
*/
fdbg("Bind method failed: %d\n", status);
blkdrvr_inode->i_crefs--;
errcode = -status;
goto errout_with_mountpt;
}
/* We have it, now populate it with driver specific information. */
INODE_SET_MOUNTPT(mountpt_inode);
mountpt_inode->u.i_mops = mops;
#ifdef CONFIG_FILE_MODE
mountpt_inode->i_mode = mode;
#endif
mountpt_inode->i_private = fshandle;
inode_semgive();
/* We can release our reference to the blkdrver_inode, if the filesystem
* wants to retain the blockdriver inode (which it should), then it must
* have called inode_addref(). There is one reference on mountpt_inode
* that will persist until umount() is called.
*/
inode_release(blkdrvr_inode);
return OK;
/* A lot of goto's! But they make the error handling much simpler */
errout_with_mountpt:
mountpt_inode->i_crefs = 0;
inode_remove(target);
inode_semgive();
inode_release(blkdrvr_inode);
inode_release(mountpt_inode);
goto errout;
errout_with_semaphore:
inode_semgive();
inode_release(blkdrvr_inode);
errout:
errno = errcode;
return ERROR;
}
#endif /* Need at least one filesystem */
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