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nuttx/fs/unionfs/fs_unionfs.c

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/****************************************************************************
* fs/unionfs/fs_unionfs.c
*
* Copyright (C) 2015 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/types.h>
#include <sys/statfs.h>
#include <sys/stat.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <semaphore.h>
#include <assert.h>
#include <errno.h>
#include <fixedmath.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/fs/unionfs.h>
#include <nuttx/fs/dirent.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/binfmt/builtin.h>
#include "inode/inode.h"
#if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_UNIONFS)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#undef MIN
#undef MAX
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#define MAX(a,b) (((a) > (b)) ? (a) : (b))
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure describes one contained file system mountpoint */
struct unionfs_mountpt_s
{
FAR struct inode *um_node; /* Filesystem inode */
FAR char *um_prefix; /* Path prefix to filesystem */
};
/* This structure describes the union file system */
struct unionfs_inode_s
{
struct unionfs_mountpt_s ui_fs[2]; /* Contained file systems */
sem_t ui_exclsem; /* Enforces mutually exclusive access */
int16_t ui_nopen; /* Number of open references */
bool ui_unhooked; /* Driver is unlinked or unbound */
};
/* This structure descries one opened file */
struct unionfs_file_s
{
uint8_t uf_ndx; /* Filesystem index */
FAR struct file uf_file; /* Filesystem open file description */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Helper functions */
static int unionfs_semtake(FAR struct unionfs_inode_s *ui, bool noint);
#define unionfs_semgive(ui) (void)sem_post(&(ui)->ui_exclsem)
static FAR const char *unionfs_trypath(FAR const char *relpath,
FAR const char *prefix);
static int unionfs_tryopen(FAR struct file *filep,
FAR const char *relpath, FAR const char *prefix, int oflags,
mode_t mode);
static int unionfs_tryopendir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix,
FAR struct fs_dirent_s *dir);
static int unionfs_trymkdir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix,
mode_t mode);
static int unionfs_tryrmdir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix);
static int unionfs_tryrename(FAR struct inode *mountpt,
FAR const char *oldrelpath, FAR const char *newrelpath,
FAR const char *prefix);
static int unionfs_trystat(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix,
FAR struct stat *buf);
static int unionfs_trystatdir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix);
static int unionfs_trystatfile(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix);
static void unionfs_unhooked(FAR struct unionfs_inode_s *ui);
static void unionfs_destroy(FAR struct unionfs_inode_s *ui);
/* Operations on opened files (with struct file) */
static int unionfs_open(FAR struct file *filep, const char *relpath,
int oflags, mode_t mode);
static int unionfs_close(FAR struct file *filep);
static ssize_t unionfs_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t unionfs_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence);
static int unionfs_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
static int unionfs_sync(FAR struct file *filep);
static int unionfs_dup(FAR const struct file *oldp,
FAR struct file *newp);
/* Operations on directories */
static int unionfs_opendir(struct inode *mountpt, const char *relpath,
FAR struct fs_dirent_s *dir);
static int unionfs_closedir(FAR struct inode *mountpt,
FAR struct fs_dirent_s *dir);
static int unionfs_readdir(FAR struct inode *mountpt,
FAR struct fs_dirent_s *dir);
static int unionfs_rewinddir(FAR struct inode *mountpt,
FAR struct fs_dirent_s *dir);
static int unionfs_unbind(FAR void *handle, FAR struct inode **blkdriver,
unsigned int flags);
static int unionfs_statfs(FAR struct inode *mountpt,
FAR struct statfs *buf);
/* Operations on paths */
static int unionfs_unlink(FAR struct inode *mountpt,
FAR const char *relpath);
static int unionfs_mkdir(FAR struct inode *mountpt,
FAR const char *relpath, mode_t mode);
static int unionfs_rmdir(FAR struct inode *mountpt,
FAR const char *relpath);
static int unionfs_rename(FAR struct inode *mountpt,
FAR const char *oldrelpath, FAR const char *newrelpath);
static int unionfs_stat(FAR struct inode *mountpt,
FAR const char *relpath, FAR struct stat *buf);
/* Initialization */
static int unionfs_getmount(FAR const char *path,
FAR struct inode **inode);
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/* See fs_mount.c -- this structure is explicitly extern'ed there.
* We use the old-fashioned kind of initializers so that this will compile
* with any compiler.
*/
static const struct mountpt_operations g_unionfs_mops =
{
unionfs_open, /* open */
unionfs_close, /* close */
unionfs_read, /* read */
unionfs_write, /* write */
unionfs_seek, /* seek */
unionfs_ioctl, /* ioctl */
unionfs_sync, /* sync */
unionfs_dup, /* dup */
unionfs_opendir, /* opendir */
unionfs_closedir, /* closedir */
unionfs_readdir, /* readdir */
unionfs_rewinddir, /* rewinddir */
NULL, /* bind */
unionfs_unbind, /* unbind */
unionfs_statfs, /* statfs */
unionfs_unlink, /* unlink */
unionfs_mkdir, /* mkdir */
unionfs_rmdir, /* rmdir */
unionfs_rename, /* rename */
unionfs_stat /* stat */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: unionfs_semtake
****************************************************************************/
static int unionfs_semtake(FAR struct unionfs_inode_s *ui, bool noint)
{
int ret;
do
{
ret = sem_wait(&ui->ui_exclsem);
if (ret < 0)
{
int errcode = errno;
DEBUGASSERT(errcode == EINTR);
if (!noint)
{
return -errcode;
}
}
}
while (ret < 0);
return OK;
}
/****************************************************************************
* Name: unionfs_trypath
****************************************************************************/
static FAR const char *unionfs_trypath(FAR const char *relpath,
FAR const char *prefix)
{
FAR const char *trypath;
int pfxlen;
/* Is there a prefix on the the path to this file system? */
if (prefix && (pfxlen = strlen(prefix)) > 0)
{
/* Does the prefix match? */
if (strncmp(prefix, relpath, pfxlen) != 0)
{
/* No, then this relative cannot be within this file system */
return NULL;
}
/* Skip over the prefix */
trypath = relpath + pfxlen;
/* Make sure that what is left is a valid, relative path */
for (; *trypath == '/'; trypath++);
}
else
{
/* No.. use the full, relative path */
trypath = relpath;
}
return trypath;
}
/****************************************************************************
* Name: unionfs_tryopen
****************************************************************************/
static int unionfs_tryopen(FAR struct file *filep, FAR const char *relpath,
FAR const char *prefix, int oflags, mode_t mode)
{
FAR const struct mountpt_operations *ops;
FAR const char *trypath;
/* Is this path valid on this file system? */
trypath = unionfs_trypath(relpath, prefix);
if (trypath == NULL)
{
/* No.. return -ENOENT */
return -ENOENT;
}
/* Yes.. try to open this directory */
DEBUGASSERT(filep->f_inode != NULL && filep->f_inode->u.i_mops != NULL);
ops = filep->f_inode->u.i_mops;
if (!ops->open)
{
return -ENOSYS;
}
return ops->open(filep, trypath, oflags, mode);
}
/****************************************************************************
* Name: unionfs_tryopendir
****************************************************************************/
static int unionfs_tryopendir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix,
FAR struct fs_dirent_s *dir)
{
FAR const struct mountpt_operations *ops;
FAR const char *trypath;
/* Is this path valid on this file system? */
trypath = unionfs_trypath(relpath, prefix);
if (trypath == NULL)
{
/* No.. return -ENOENT */
return -ENOENT;
}
/* Yes.. Try to open this directory */
ops = inode->u.i_mops;
DEBUGASSERT(ops && ops->opendir);
if (!ops->opendir)
{
return -ENOSYS;
}
return ops->opendir(inode, trypath, dir);
}
/****************************************************************************
* Name: unionfs_trymkdir
****************************************************************************/
static int unionfs_trymkdir(FAR struct inode *inode, FAR const char *relpath,
FAR const char *prefix, mode_t mode)
{
FAR const struct mountpt_operations *ops;
FAR const char *trypath;
/* Is this path valid on this file system? */
trypath = unionfs_trypath(relpath, prefix);
if (trypath == NULL)
{
/* No.. return -ENOENT */
return -ENOENT;
}
/* Yes.. Try to create the directory */
ops = inode->u.i_mops;
if (!ops->mkdir)
{
return -ENOSYS;
}
return ops->mkdir(inode, trypath, mode);
}
/****************************************************************************
* Name: unionfs_trystat
****************************************************************************/
static int unionfs_tryrename(FAR struct inode *mountpt,
FAR const char *oldrelpath,
FAR const char *newrelpath,
FAR const char *prefix)
{
FAR const struct mountpt_operations *ops;
FAR const char *tryoldpath;
FAR const char *trynewpath;
/* Is source path valid on this file system? */
tryoldpath = unionfs_trypath(oldrelpath, prefix);
if (tryoldpath == NULL)
{
/* No.. return -ENOENT. This should not fail because the existence
* of the file has already been verified.
*/
return -ENOENT;
}
/* Is source path valid on this file system?
* REVISIT: There is no logic currently to rename the file by copying i
* to a different file system. So we just fail if the destination name
* is not within the same file system. I might, however, be on the other
* file system and that rename should be supported as a file copy and
* delete.
*/
trynewpath = unionfs_trypath(newrelpath, prefix);
if (trynewpath == NULL)
{
/* No.. return -ENOSYS. We should be able to do this, but we can't
* yet.
*/
return -ENOSYS;
}
/* Yes.. Try to rename the file */
ops = mountpt->u.i_mops;
if (!ops->rename)
{
return -ENOSYS;
}
return ops->rename(mountpt, tryoldpath, trynewpath);
}
/****************************************************************************
* Name: unionfs_trystat
****************************************************************************/
static int unionfs_trystat(FAR struct inode *inode, FAR const char *relpath,
FAR const char *prefix, FAR struct stat *buf)
{
FAR const struct mountpt_operations *ops;
FAR const char *trypath;
/* Is this path valid on this file system? */
trypath = unionfs_trypath(relpath, prefix);
if (trypath == NULL)
{
/* No.. return -ENOENT */
return -ENOENT;
}
/* Yes.. Try to create the directory */
ops = inode->u.i_mops;
if (!ops->stat)
{
return -ENOSYS;
}
return ops->stat(inode, trypath, buf);
}
/****************************************************************************
* Name: unionfs_trystatdir
****************************************************************************/
static int unionfs_trystatdir(FAR struct inode *inode,
FAR const char *relpath,
FAR const char *prefix)
{
FAR struct stat buf;
int ret;
/* Check if relative path refers to a directory. */
ret = unionfs_trystat(inode, relpath, prefix, &buf);
if (ret >= 0 && !S_ISDIR(buf.st_mode))
{
return -ENOTDIR;
}
return ret;
}
/****************************************************************************
* Name: unionfs_trystatdir
****************************************************************************/
static int unionfs_trystatfile(FAR struct inode *inode,
FAR const char *relpath,
FAR const char *prefix)
{
FAR struct stat buf;
int ret;
/* Check if relative path refers to a regular file. We specifically
* exclude directories but neither do we expect any kind of special file
* to reside on the mounted filesystem.
*/
ret = unionfs_trystat(inode, relpath, prefix, &buf);
if (ret >= 0 && !S_ISREG(buf.st_mode))
{
return -EISDIR;
}
return ret;
}
/****************************************************************************
* Name: unionfs_tryrmdir
****************************************************************************/
static int unionfs_tryrmdir(FAR struct inode *inode, FAR const char *relpath,
FAR const char *prefix)
{
FAR const struct mountpt_operations *ops;
FAR const char *trypath;
/* Is this path valid on this file system? */
trypath = unionfs_trypath(relpath, prefix);
if (trypath == NULL)
{
/* No.. return -ENOENT */
return -ENOENT;
}
/* Yes.. Try to create the directory */
ops = inode->u.i_mops;
if (!ops->rmdir)
{
return -ENOSYS;
}
return ops->rmdir(inode, trypath);
}
/****************************************************************************
* Name: unionfs_unhooked
****************************************************************************/
static void unionfs_unhooked(FAR struct unionfs_inode_s *ui)
{
fvdbg("Entry\n");
DEBUGASSERT(ui);
/* Mark the file system as unhooked (unlinked or unmounted) */
ui->ui_unhooked = true;
/* If there are no open references, then we can destroy the file system
* now.
*/
if (ui->ui_nopen <= 0)
{
unionfs_destroy(ui);
}
}
/****************************************************************************
* Name: unionfs_destroy
****************************************************************************/
static void unionfs_destroy(FAR struct unionfs_inode_s *ui)
{
DEBUGASSERT(ui != NULL && ui->ui_fs[0].um_node != NULL &&
ui->ui_fs[1].um_node != NULL && ui->ui_nopen == 0);
/* Release our references on the contained inodes */
inode_release(ui->ui_fs[0].um_node);
inode_release(ui->ui_fs[1].um_node);
/* Free any allocated prefix strings */
if (ui->ui_fs[1].um_prefix)
{
kmm_free(ui->ui_fs[0].um_prefix);
}
if (ui->ui_fs[1].um_prefix)
{
kmm_free(ui->ui_fs[1].um_prefix);
}
/* And finally free the allocated unionfs state structure as well */
sem_destroy(&ui->ui_exclsem);
kmm_free(ui);
}
/****************************************************************************
* Name: unionfs_open
****************************************************************************/
static int unionfs_open(FAR struct file *filep, FAR const char *relpath,
int oflags, mode_t mode)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
int ret;
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
fvdbg("Opening: ui_nopen=%d\n", ui->ui_nopen);
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* Alloate a container to hold the open file system information */
uf = (FAR struct unionfs_file_s *)kmm_malloc(sizeof(struct unionfs_file_s));
if (uf == NULL)
{
ret = -ENOMEM;
goto errout_with_semaphore;
}
/* Try to open the file on file system 1 */
um = &ui->ui_fs[0];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
uf->uf_file.f_oflags = filep->f_oflags;
uf->uf_file.f_pos = 0;
uf->uf_file.f_inode = um->um_node;
uf->uf_file.f_priv = NULL;
ret = unionfs_tryopen(&uf->uf_file, relpath, um->um_prefix, oflags, mode);
if (ret >= 0)
{
/* Successfully opened on file system 1 */
uf->uf_ndx = 0;
}
else
{
/* Try to open the file on file system 1 */
um = &ui->ui_fs[1];
uf->uf_file.f_oflags = filep->f_oflags;
uf->uf_file.f_pos = 0;
uf->uf_file.f_inode = um->um_node;
uf->uf_file.f_priv = NULL;
ret = unionfs_tryopen(&uf->uf_file, relpath, um->um_prefix, oflags, mode);
if (ret < 0)
{
goto errout_with_semaphore;
}
/* Successfully opened on file system 1 */
uf->uf_ndx = 1;
}
filep->f_priv = (FAR void *)uf;
ret = OK;
errout_with_semaphore:
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_close
****************************************************************************/
static int unionfs_close(FAR struct file *filep)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = OK;
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
(void)unionfs_semtake(ui, false);
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
fvdbg("Closing: ui_nopen=%d\n", ui->ui_nopen);
/* Perform the lower level close operation */
if (ops->close)
{
ret = ops->close(&uf->uf_file);
}
/* Decrement the count of open reference. If that count would go to zero
* and if the file system has been unmounted or if the mountpoint has been
* unlinked, then destroy the file system now.
*/
if (--ui->ui_nopen <= 0)
{
unionfs_destroy(ui);
}
/* Free the open file container */
kmm_free(uf);
filep->f_priv = NULL;
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_read
****************************************************************************/
static ssize_t unionfs_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = -EPERM;
fvdbg("buflen: %lu\n", (unsigned long)buflen);
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level write operation */
if (ops->read)
{
ret = ops->read(&uf->uf_file, buffer, buflen);
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_write
****************************************************************************/
static ssize_t unionfs_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = -EPERM;
fvdbg("buflen: %lu\n", (unsigned long)buflen);
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level write operation */
if (ops->write)
{
ret = ops->write(&uf->uf_file, buffer, buflen);
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_seek
****************************************************************************/
static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret;
fvdbg("offset: %lu whence: %d\n", (unsigned long)off_t, whence);
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Invoke the file seek method if available */
if (ops->seek)
{
offset = ops->seek(&uf->uf_file, offset, whence);
}
else
{
/* No... Just set the common file position value */
switch (whence)
{
case SEEK_CUR:
offset += filep->f_pos;
case SEEK_SET:
if (offset >= 0)
{
filep->f_pos = offset; /* Might be beyond the end-of-file */
}
else
{
offset = (off_t)-EINVAL;
}
break;
case SEEK_END:
offset = (off_t)-ENOSYS;
break;
default:
offset = (off_t)-EINVAL;
break;
}
}
unionfs_semgive(ui);
return offset;
}
/****************************************************************************
* Name: unionfs_ioctl
****************************************************************************/
static int unionfs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = -ENOTTY;
fvdbg("cmd: %d arg: %lu\n", cmd, arg);
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level ioctl operation */
if (ops->ioctl)
{
ret = ops->ioctl(&uf->uf_file, cmd, arg);
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_sync
****************************************************************************/
static int unionfs_sync(FAR struct file *filep)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_file_s *uf;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = -EINVAL;
fvdbg("Entry\n");
/* Recover the open file data from the struct file instance */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
uf = (FAR struct unionfs_file_s *)filep->f_priv;
DEBUGASSERT(uf->uf_ndx == 0 || uf->uf_ndx == 1);
um = &ui->ui_fs[uf->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level sync operation */
if (ops->sync)
{
ret = ops->sync(&uf->uf_file);
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_dup
****************************************************************************/
static int unionfs_dup(FAR const struct file *oldp, FAR struct file *newp)
{
FAR struct unionfs_file_s *oldpriv;
FAR struct unionfs_file_s *newpriv;
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
int ret = -ENOMEM;
fvdbg("Entry\n");
/* Recover the open file data from the struct file instance */
DEBUGASSERT(oldp != NULL && oldp->f_inode != NULL);
ui = (FAR struct unionfs_inode_s *)oldp->f_inode->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(ui != NULL && oldp->f_priv != NULL);
oldpriv = (FAR struct unionfs_file_s *)oldp->f_priv;
DEBUGASSERT(oldpriv->uf_ndx == 0 || oldpriv->uf_ndx == 1);
um = &ui->ui_fs[oldpriv->uf_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
DEBUGASSERT(newp != NULL && newp->f_priv == NULL);
/* Allocate a new container for the union FS open file */
newpriv = (FAR struct unionfs_file_s *)kmm_malloc(sizeof(struct unionfs_file_s));
if (newpriv != NULL)
{
/* Clone the old file structure into the newly allocated one */
memcpy(newpriv, oldpriv, sizeof(struct unionfs_file_s));
newpriv->uf_file.f_priv = NULL;
/* Then perform the lower lowel dup operation */
ret = OK;
if (ops->dup)
{
ret = ops->dup(&oldpriv->uf_file, &newpriv->uf_file);
if (ret < 0)
{
kmm_free(newpriv);
newpriv = NULL;
}
}
/* Save the new container in the new file structure */
newp->f_priv = newpriv;
}
return ret;
}
/****************************************************************************
* Name: unionfs_opendir
****************************************************************************/
static int unionfs_opendir(FAR struct inode *mountpt, FAR const char *relpath,
FAR struct fs_dirent_s *dir)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR struct fs_unionfsdir_s *fu;
FAR const struct mountpt_operations *ops;
FAR struct fs_dirent_s *lowerdir;
int ret;
fvdbg("relpath: \"%s\"\n", relpath ? relpath : "NULL");
/* Recover the filesystem data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
goto errout_with_lowerdir;
}
DEBUGASSERT(dir);
fu = &dir->u.unionfs;
/* Allocate another dirent structure for the lower file system */
lowerdir = (FAR struct fs_dirent_s *)kmm_zalloc(sizeof(struct fs_dirent_s));
if (lowerdir == NULL)
{
return -ENOMEM;
}
/* Check file system 2 first. */
fu->fu_ndx = 0;
fu->fu_lower[0] = NULL;
fu->fu_lower[1] = NULL;
um = &ui->ui_fs[1];
lowerdir->fd_root = um->um_node;
ret = unionfs_tryopendir(um->um_node, relpath, um->um_prefix, lowerdir);
if (ret >= 0)
{
/* Save the filsystem2 access info */
fu->fu_ndx = 1;
fu->fu_lower[1] = lowerdir;
/* Allocate yet another dirent structure for the lower file system 1 */
lowerdir = (FAR struct fs_dirent_s *)kmm_zalloc(sizeof(struct fs_dirent_s));
if (lowerdir == NULL)
{
ret = -ENOMEM;
goto errout_with_fs2open;
}
}
/* Check file system 1 last, possibly overwriting fu_ndx */
um = &ui->ui_fs[1];
lowerdir->fd_root = um->um_node;
ret = unionfs_tryopendir(um->um_node, relpath, um->um_prefix, lowerdir);
if (ret >= 0)
{
/* Save the filsystem1 access info */
fu->fu_ndx = 0;
fu->fu_lower[0] = lowerdir;
}
else if (fu->fu_lower[1] == NULL)
{
/* Neither file system was opened! */
goto errout_with_lowerdir;
}
/* Increment the number of open references and return success */
ui->ui_nopen++;
DEBUGASSERT(ui->ui_nopen > 0);
unionfs_semgive(ui);
return OK;
errout_with_fs2open:
ops = ui->ui_fs[1].um_node->u.i_mops;
DEBUGASSERT(ops != NULL);
if (ops->closedir)
{
ret = ops->closedir(um->um_node, fu->fu_lower[fu->fu_ndx]);
}
errout_with_lowerdir:
kmm_free(lowerdir);
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_closedir
****************************************************************************/
static int unionfs_closedir(FAR struct inode *mountpt,
FAR struct fs_dirent_s *dir)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
FAR struct fs_unionfsdir_s *fu;
int ret = OK;
int i;
fvdbg("Entry\n");
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
(void)unionfs_semtake(ui, true);
DEBUGASSERT(dir);
fu = &dir->u.unionfs;
/* Close both contained file systems */
for (i = 0; i < 2; i++)
{
/* Was this file system opened? */
if (fu->fu_lower[i] != NULL);
{
um = &ui->ui_fs[i];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level closedir operation */
if (ops->closedir)
{
ret = ops->closedir(um->um_node, fu->fu_lower[i]);
}
/* Free the lower dirent structure */
kmm_free(fu->fu_lower[i]);
}
}
fu->fu_ndx = 0;
fu->fu_lower[0] = NULL;
fu->fu_lower[1] = NULL;
/* Decrement the count of open reference. If that count would go to zero
* and if the file system has been unmounted or if the mountpoint has been
* unlinked, then destroy the file system now.
*/
if (--ui->ui_nopen <= 0 && ui->ui_unhooked)
{
unionfs_destroy(ui);
}
else
{
unionfs_semgive(ui);
}
return ret;
}
/****************************************************************************
* Name: unionfs_readdir
****************************************************************************/
static int unionfs_readdir(struct inode *mountpt, struct fs_dirent_s *dir)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
FAR struct fs_unionfsdir_s *fu;
int ret = -ENOSYS;
fvdbg("Entry\n");
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
DEBUGASSERT(dir);
fu = &dir->u.unionfs;
DEBUGASSERT(fu->fu_ndx == 0 || fu->fu_ndx == 1);
um = &ui->ui_fs[fu->fu_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the lower level readdir operation */
if (ops->readdir)
{
ret = ops->readdir(um->um_node, fu->fu_lower[fu->fu_ndx]);
/* Did the read operation fail because we reached the end of the
* directory? In that case, the error would be -ENOENT. If we hit
* the end-of-directory on file system, we need to seamlessly move
* to the second file system (if there is one).
*/
if (ret == -ENOENT && fu->fu_ndx == 0 && fu->fu_lower[1] != NULL)
{
/* Switch to the second file system */
fu->fu_ndx = 1;
um = &ui->ui_fs[1];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Make sure that the second file system directory enumeration
* is rewound to the beginning of the directory.
*/
if (ops->rewinddir != NULL)
{
ret = ops->rewinddir(um->um_node, fu->fu_lower[1]);
}
/* Then try the read operation again */
ret = ops->readdir(um->um_node, fu->fu_lower[1]);
}
/* Copy the return information into the diret structure that the
* application will see.
*/
dir->fd_position = fu->fu_lower[fu->fu_ndx]->fd_position;
memcpy(&dir->fd_dir, &fu->fu_lower[fu->fu_ndx]->fd_dir, sizeof(struct dirent));
}
return ret;
}
/****************************************************************************
* Name: unionfs_rewindir
****************************************************************************/
static int unionfs_rewinddir(struct inode *mountpt, struct fs_dirent_s *dir)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
FAR struct fs_unionfsdir_s *fu;
int ret;
fvdbg("Entry\n");
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(dir);
fu = &dir->u.unionfs;
/* Were we currently enumerating on file system 1? If not, is an
* enumeration possible on file system 1?
*/
DEBUGASSERT(fu->fu_ndx == 0 || fu->fu_ndx == 1);
if (/* fu->fu_ndx != 0 && */ fu->fu_lower[0] != 0)
{
/* Yes.. switch to file system 1 */
fu->fu_ndx = 0;
}
um = &ui->ui_fs[fu->fu_ndx];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Perform the file system rewind operation */
if (ops->rewinddir != NULL)
{
ret = ops->rewinddir(um->um_node, fu->fu_lower[fu->fu_ndx]);
dir->fd_position = fu->fu_lower[fu->fu_ndx]->fd_position;
}
else
{
ret = -EINVAL;
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_unbind
****************************************************************************/
static int unionfs_unbind(FAR void *handle, FAR struct inode **blkdriver,
unsigned int flags)
{
unionfs_unhooked((FAR struct unionfs_inode_s *)handle);
return OK;
}
/****************************************************************************
* Name: unionfs_statfs
****************************************************************************/
static int unionfs_statfs(FAR struct inode *mountpt, FAR struct statfs *buf)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR const struct mountpt_operations *ops;
FAR struct statfs *adj;
struct statfs buf1;
struct statfs buf2;
uint64_t tmp;
uint32_t ratiob16;
int ret;
fvdbg("Entry\n");
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* Get statfs info from file system 1 */
um = &ui->ui_fs[0];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
if (ops->statfs)
{
ret = ops->statfs(um->um_node, &buf1);
if (ret < 0)
{
goto errout_with_semaphore;
}
}
/* Get statfs info from file system 2 */
um = &ui->ui_fs[1];
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
if (ops->statfs)
{
ret = ops->statfs(um->um_node, &buf2);
if (ret < 0)
{
goto errout_with_semaphore;
}
}
/* Now try to reconcile the statfs info */
memset(buf, 0, sizeof(struct statfs));
buf->f_type = UNIONFS_MAGIC;
buf->f_namelen = MIN(buf1.f_namelen, buf2.f_namelen);
buf->f_files = buf1.f_files + buf2.f_files;
buf->f_ffree = buf1.f_ffree + buf2.f_ffree;
/* Things expressed in units of blocks are the only tricky ones. We will
* depend on a uint64_t * temporary to avoid arithmetic overflow.
*/
if (buf1.f_bsize != buf2.f_bsize)
{
if (buf1.f_bsize < buf2.f_bsize)
{
buf->f_bsize = buf1.f_bsize;
tmp = (((uint64_t)buf2.f_blocks * (uint64_t)buf2.f_bsize) << 16);
ratiob16 = (uint32_t)(tmp / buf1.f_bsize);
adj = &buf2;
}
else
{
buf->f_bsize = buf2.f_bsize;
tmp = (((uint64_t)buf1.f_blocks * (uint64_t)buf1.f_bsize) << 16);
ratiob16 = (uint32_t)(tmp / buf2.f_bsize);
adj = &buf2;
}
tmp = (uint16_t)adj->f_blocks * ratiob16;
adj->f_blocks = (off_t)(tmp >> 16);
tmp = (uint16_t)adj->f_bfree * ratiob16;
adj->f_bfree = (off_t)(tmp >> 16);
tmp = (uint16_t)adj->f_bavail * ratiob16;
adj->f_bavail = (off_t)(tmp >> 16);
}
/* Then we can just sum the adjusted sizes */
buf->f_blocks = buf1.f_blocks + buf2.f_blocks;
buf->f_bfree = buf1.f_bfree + buf2.f_bfree;
buf->f_bavail = buf1.f_bavail + buf2.f_bavail;
ret = OK;
errout_with_semaphore:
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_unlink
****************************************************************************/
static int unionfs_unlink(FAR struct inode *mountpt,
FAR const char *relpath)
{
FAR struct unionfs_inode_s *ui;
int ret;
fdbg("relpath: %s\n", relpath);
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL && relpath != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* Unhook/unlink the union file system */
unionfs_unhooked((FAR struct unionfs_inode_s *)mountpt->i_private);
unionfs_semgive(ui);
return OK;
}
/****************************************************************************
* Name: unionfs_mkdir
****************************************************************************/
static int unionfs_mkdir(FAR struct inode *mountpt, FAR const char *relpath,
mode_t mode)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
struct stat buf;
int ret1;
int ret2;
int ret;
fdbg("relpath: %s\n", relpath);
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL && relpath != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* Is there anything with this name on either file system? */
um = &ui->ui_fs[0];
ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, &buf);
if (ret >= 0)
{
ret = -EEXIST;
goto errout_with_semaphore;
}
um = &ui->ui_fs[1];
ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, &buf);
if (ret >= 0)
{
ret = -EEXIST;
goto errout_with_semaphore;
}
/* Try to create the directory on both file systems. */
um = &ui->ui_fs[0];
ret1 = unionfs_trymkdir(um->um_node, relpath, um->um_prefix, mode);
um = &ui->ui_fs[1];
ret2 = unionfs_trymkdir(um->um_node, relpath, um->um_prefix, mode);
/* We will say we were successful if we were able to create the
* directory on either file system. Perhaps one file system is
* read-only and the other is write-able?
*/
if (ret1 >= 0 || ret2 >= 0)
{
ret = OK;
}
else
{
/* Otherwise, pick one */
ret = ret1;
}
errout_with_semaphore:
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_rmdir
****************************************************************************/
static int unionfs_rmdir(FAR struct inode *mountpt, FAR const char *relpath)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
int tmp;
int ret = -ENOENT;
fdbg("relpath: %s\n", relpath);
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL && relpath != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* We really don't know any better so we will try to remove the directory
* from both file systems.
*/
/* Is there a directory with this name on file system 1 */
um = &ui->ui_fs[0];
tmp = unionfs_trystatdir(um->um_node, relpath, um->um_prefix);
if (tmp >= 0)
{
/* Yes.. remove it. Since we know that the directory exists, any
* failure to remove it is a showstopper.
*/
ret = unionfs_tryrmdir(um->um_node, relpath, um->um_prefix);
if (ret < 0)
{
unionfs_semgive(ui);
return ret;
}
}
/* Either the directory does not exist on file system 1, or we
* successfully removed it. Try again on file system 2.
*/
um = &ui->ui_fs[1];
tmp = unionfs_trystatdir(um->um_node, relpath, um->um_prefix);
if (tmp >= 0)
{
/* Yes.. remove it. Since we know that the directory exists, any
* failure to remove it is a showstopper.
*/
ret = unionfs_tryrmdir(um->um_node, relpath, um->um_prefix);
/* REVISIT: Should we try to restore the directory on file system 1
* if we failure to removed the directory on file system 2?
*/
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_rename
****************************************************************************/
static int unionfs_rename(FAR struct inode *mountpt,
FAR const char *oldrelpath,
FAR const char *newrelpath)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
int tmp;
int ret = -ENOENT;
fdbg("oldrelpath: %s newrelpath\n", oldrelpath, newrelpath);
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
DEBUGASSERT(oldrelpath != NULL && oldrelpath != NULL);
/* Is there a file with this name on file system 1 */
um = &ui->ui_fs[0];
tmp = unionfs_trystatfile(um->um_node, oldrelpath, um->um_prefix);
if (tmp >= 0)
{
/* Yes.. rename it. Since we know that the directory exists, any
* failure to remove it is a showstopper.
*/
ret = unionfs_tryrename(um->um_node, oldrelpath, newrelpath,
um->um_prefix);
if (ret >= 0)
{
/* Return immediately on success. In the event that the file
* exists in both file systems, this will produce the odd behavior
* that one file on file system 1 was renamed but another obscured
* file of the same relative path will become visible.
*/
unionfs_semgive(ui);
return OK;
}
}
/* Either the file does not exist on file system 1, or we failed to rename
* it (perhaps because the file system was read-only). Try again on file
* system 2.
*/
um = &ui->ui_fs[1];
tmp = unionfs_trystatfile(um->um_node, oldrelpath, um->um_prefix);
if (tmp >= 0)
{
/* Yes.. remove it. Since we know that the directory exists, any
* failure to remove it is a showstopper.
*/
ret = unionfs_tryrename(um->um_node, oldrelpath, newrelpath,
um->um_prefix);
}
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_stat
****************************************************************************/
static int unionfs_stat(FAR struct inode *mountpt, FAR const char *relpath,
FAR struct stat *buf)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
int ret;
fdbg("relpath: %s\n", relpath);
/* Recover the union file system data from the struct inode instance */
DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL && relpath != NULL);
ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
/* Get exclusive access to the file system data structures */
ret = unionfs_semtake(ui, false);
if (ret < 0)
{
return ret;
}
/* stat this path on file system 1 */
um = &ui->ui_fs[0];
ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, buf);
if (ret >= 0)
{
/* Return on the first success. The first instance of the file will
* shadow the second anyway.
*/
unionfs_semgive(ui);
return OK;
}
/* stat failed on the file system 1. Try again on file system 2. */
um = &ui->ui_fs[1];
ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, buf);
unionfs_semgive(ui);
return ret;
}
/****************************************************************************
* Name: unionfs_getmount
****************************************************************************/
static int unionfs_getmount(FAR const char *path, FAR struct inode **inode)
{
FAR struct inode *minode;
/* Find the mountpt */
minode = inode_find(path, NULL);
if (!minode)
{
/* Mountpoint inode not found */
return -ENOENT;
}
/* Verify that the inode is a mountpoint */
if (!INODE_IS_MOUNTPT(minode))
{
/* Inode was found, but is it is a mounpoint */
inode_release(minode);
return -EINVAL;
}
/* Success! */
*inode = minode;
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: unionfs_mount
*
* Description:
* Create and mount a union file system
*
* Input Parameters:
* fspath1 - The full path to the first file system mountpoint
* prefix1 - An optiona prefix that may be applied to make the first
* file system appear a some path below the unionfs mountpoint,
* fspath2 - The full path to the second file system mountpoint
* prefix2 - An optiona prefix that may be applied to make the first
* file system appear a some path below the unionfs mountpoint,
* mountpt - The full path to the mountpoint for the union file system
*
* Returned value:
* Zero (OK) is returned if the union file system was correctly created and
* mounted. On any failure, a negated error value will be returned to
* indicate the nature of the failure.
*
****************************************************************************/
int unionfs_mount(FAR const char *fspath1, FAR const char *prefix1,
FAR const char *fspath2, FAR const char *prefix2,
FAR const char *mountpt)
{
FAR struct unionfs_inode_s *ui;
FAR struct inode *mpinode;
int ret;
DEBUGASSERT(fspath1 != NULL && fspath2 != NULL && mountpt != NULL);
/* Allocate a structure a structure that will describe the union file
* system.
*/
ui = (FAR struct unionfs_inode_s *)kmm_zalloc(sizeof(struct unionfs_inode_s));
if (!ui)
{
fdbg("ERROR: Failed to allocated union FS state structure\n");
return -ENOMEM;
}
sem_init(&ui->ui_exclsem, 0, 1);
/* Get the inodes associated with fspath1 and fspath2 */
ret = unionfs_getmount(fspath1, &ui->ui_fs[0].um_node);
if (ret < 0)
{
fdbg("ERROR: unionfs_getmount(fspath1) failed: %d\n", ret);
goto errout_with_uinode;
}
ret = unionfs_getmount(fspath2, &ui->ui_fs[1].um_node);
if (ret < 0)
{
fdbg("ERROR: unionfs_getmount(fspath2) failed: %d\n", ret);
goto errout_with_fs1;
}
/* Duplicate the prefix strings */
if (prefix1 && strlen(prefix1) > 0)
{
ui->ui_fs[0].um_prefix = strdup(prefix1);
if (ui->ui_fs[0].um_prefix == NULL)
{
fdbg("ERROR: strdup(prefix1) failed\n");
ret = -ENOMEM;
goto errout_with_fs2;
}
}
if (prefix2 && strlen(prefix2) > 0)
{
ui->ui_fs[1].um_prefix = strdup(prefix2);
if (ui->ui_fs[1].um_prefix == NULL)
{
fdbg("ERROR: strdup(prefix2) failed\n");
ret = -ENOMEM;
goto errout_with_prefix1;
}
}
/* Finally, mount the union FS. We should adapt the standard mount to do
* this using optional parameters. This custom mount should do the job
* for now, however.
*/
/* Insert a dummy node -- we need to hold the inode semaphore
* to do this because we will have a momentarily bad structure.
*/
inode_semtake();
ret = inode_reserve(mountpt, &mpinode);
if (ret < 0)
{
/* inode_reserve can fail for a couple of reasons, but the most likely
* one is that the inode already exists. inode_reserve may return:
*
* -EINVAL - 'path' is invalid for this operation
* -EEXIST - An inode already exists at 'path'
* -ENOMEM - Failed to allocate in-memory resources for the operation
*/
fdbg("ERROR: Failed to reserve inode\n");
goto errout_with_semaphore;
}
/* Populate the inode with driver specific information. */
INODE_SET_MOUNTPT(mpinode);
mpinode->u.i_mops = &g_unionfs_mops;
#ifdef CONFIG_FILE_MODE
mpinode->i_mode = 0755;
#endif
mpinode->i_private = ui;
/* Unlink the contained mountpoint inodes from the pseudo file system.
* The inodes will be marked as deleted so that they will be removed when
* the reference count decrements to zero in inode_release(). Because we
* hold a reference count on the inodes, they will not be deleted until
* this logic calls inode_release() in the unionfs_destroy() function.
*/
(void)inode_remove(fspath1);
(void)inode_remove(fspath2);
inode_semgive();
return OK;
errout_with_semaphore:
inode_semgive();
//errout_with_prefix2:
if (ui->ui_fs[1].um_prefix != NULL)
{
kmm_free(ui->ui_fs[1].um_prefix);
}
errout_with_prefix1:
if (ui->ui_fs[0].um_prefix != NULL)
{
kmm_free(ui->ui_fs[0].um_prefix);
}
errout_with_fs2:
inode_release(ui->ui_fs[1].um_node);
errout_with_fs1:
inode_release(ui->ui_fs[0].um_node);
errout_with_uinode:
sem_destroy(&ui->ui_exclsem);
kmm_free(ui);
return ret;
}
#endif /* !CONFIG_DISABLE_MOUNTPOINT && CONFIG_FS_UNIONFS */
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