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Fix an error in opendir() when a mountpoint is in the root directory.

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3432 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2011-03-28 17:43:34 +00:00
parent a082aebc77
commit 2ffccdc2c5
2 changed files with 143 additions and 71 deletions
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4
ChangeLog
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@ -1623,4 +1623,8 @@
of the nuttx source tree
* apps/namedapp/binfs.c: Create a tiny filesystem that can be used
to show the internal named apps under /bin.
* fs/fs_opendir.c: Correct an error that occurs when a file system is
mounted in the root directory. This was discovered while mounting
the named app's /bin directory.

210
fs/fs_opendir.c
View file

@ -55,6 +55,108 @@
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: open_mountpoint
*
* Description:
* Handle the case where the inode to be opened is within a mountpoint.
*
* Inputs:
* inode -- the inode of the mountpoint to open
* relpath -- the relative path within the mountpoint to open
* dir -- the dirent structure to be initialized
*
* Return:
* On success, OK is returned; Otherwise, a positive errno is returned.
*
****************************************************************************/
#ifndef CONFIG_DISABLE_MOUNTPOINT
static inline int open_mountpoint(FAR struct inode *inode,
FAR const char *relpath,
FAR struct fs_dirent_s *dir)
{
int ret;
/* The inode itself as the 'root' of mounted volume. The actually
* directory is at relpath into the* mounted filesystem.
*
*
* Verify that the mountpoint inode supports the opendir() method
*/
if (!inode->u.i_mops || !inode->u.i_mops->opendir)
{
return ENOSYS;
}
/* Take reference to the mountpoint inode (fd_root). Note that we do
* not use inode_addref() because we already hold the tree semaphore.
*/
inode->i_crefs++;
/* Perform the opendir() operation */
ret = inode->u.i_mops->opendir(inode, relpath, dir);
if (ret < 0)
{
/* We now need to back off our reference to the inode. We can't
* call inode_release() to do that unless we release the tree
* semaphore. The following should be safe because: (1) after the
* reference count was incremented above it should be >=1 so it should
* not decrement below zero, and (2) we hold the tree semaphore so no
* other thread should be able to change the reference count.
*/
inode->i_crefs--;
DEBUGASSERT(inode->i_crefs >= 0);
/* Negate the error value so that it can be used to set errno */
return -ret;
}
return OK;
}
#endif
/****************************************************************************
* Name: open_pseudodir
*
* Description:
* Handle the case where the inode to be opened is within the top-level
* pseudo-file system.
*
* Inputs:
* inode -- the inode of the mountpoint to open
* dir -- the dirent structure to be initialized
*
* Return:
* On success, OK is returned; Otherwise, a positive errno is returned.
*
****************************************************************************/
#ifndef CONFIG_DISABLE_MOUNTPOINT
static void open_pseudodir(FAR struct inode *inode, FAR struct fs_dirent_s *dir)
{
/* We have a valid psuedo-filesystem node. Take two references on the
* inode -- one for the parent (fd_root) and one for the child (fd_next).
* Note that we do not call inode_addref because we are holding the tree
* semaphore and that would result in deadlock.
*/
inode->i_crefs += 2;
dir->u.psuedo.fd_next = inode; /* This is the next node to use for readdir() */
/* Flag the inode as belonging to the psuedo-filesystem */
#ifndef CONFIG_DISABLE_MOUNTPOINT
DIRENT_SETPSUEDONODE(dir->fd_flags);
#endif
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
@ -63,18 +165,16 @@
* Name: opendir
*
* Description:
* The opendir() function opens a directory stream
* corresponding to the directory name, and returns a
* pointer to the directory stream. The stream is
* positioned at the first entry in the directory.
* The opendir() function opens a directory stream corresponding to the
* directory name, and returns a pointer to the directory stream. The
* stream is positioned at the first entry in the directory.
*
* Inputs:
* path -- the directory to open
*
* Return:
* The opendir() function returns a pointer to the
* directory stream. On error, NULL is returned, and
* errno is set appropriately.
* The opendir() function returns a pointer to the directory stream. On
* error, NULL is returned, and errno is set appropriately.
*
* EACCES - Permission denied.
* EMFILE - Too many file descriptors in use by process.
@ -92,7 +192,7 @@ FAR DIR *opendir(FAR const char *path)
FAR struct inode *inode = NULL;
FAR struct fs_dirent_s *dir;
FAR const char *relpath;
bool isroot = false;
bool bisroot = false;
int ret;
/* If we are given 'nothing' then we will interpret this as
@ -102,8 +202,9 @@ FAR DIR *opendir(FAR const char *path)
inode_semtake();
if (!path || *path == 0 || strcmp(path, "/") == 0)
{
inode = root_inode;
isroot = true;
inode = root_inode;
bisroot = true;
relpath = NULL;
}
else
{
@ -151,85 +252,52 @@ FAR DIR *opendir(FAR const char *path)
dir->fd_root = inode; /* Save the inode where we start */
dir->fd_position = 0; /* This is the position in the read stream */
/* Is this a node in the psuedo filesystem? Or a mountpoint? */
/* First, handle the special case of the root inode. This must be
* special-cased here because the root inode might ALSO be a mountpoint.
*/
if (bisroot)
{
/* Whatever payload the root inode carries, the root inode is always
* a directory inode in the pseudo-file system
*/
open_pseudodir(inode, dir);
}
/* Is this a node in the psuedo filesystem? Or a mountpoint? If the node
* is the root (bisroot == TRUE), then this is a special case.
*/
#ifndef CONFIG_DISABLE_MOUNTPOINT
if (INODE_IS_MOUNTPT(inode))
else if (INODE_IS_MOUNTPT(inode))
{
/* Yes, then return the inode itself as the 'root' of
* the directory. The actually directory is at relpath into the
* mounted filesystem.
*/
/* Yes, the node is a file system mointpoint. */
/* The node is a file system mointpoint. Verify that the mountpoint
* supports the opendir() method
*/
if (!inode->u.i_mops || !inode->u.i_mops->opendir)
ret = open_mountpoint(inode, relpath, dir);
if (ret != OK)
{
ret = ENOSYS;
goto errout_with_direntry;
}
/* Take reference to the mountpoint inode (fd_root). Note that we do
* not use inode_addref() because we already hold the tree semaphore.
*/
inode->i_crefs++;
/* Perform the opendir() operation */
ret = inode->u.i_mops->opendir(inode, relpath, dir);
if (ret < 0)
{
/* We now need to back off our reference to the inode. We can't
* call inode_release() to do that unless we release the tree
* semaphore. The following should be safe because: (1) after the
* reference count was incremented above it should be >=1 so it should
* not decrement below zero, and (2) we hold the tree semaphore so no
* other thread should be able to change the reference count.
*/
inode->i_crefs--;
DEBUGASSERT(inode->i_crefs >= 0);
/* Negate the error value so that it can be used to set errno */
ret = -ret;
goto errout_with_direntry;
}
}
else
#endif
else
{
/* The node is part of the root psuedo file system. Does the inode have a child?
* If so that the child would be the 'root' of a list of nodes under
* the directory.
*/
if (!isroot)
inode = inode->i_child;
if (!inode)
{
inode = inode->i_child;
if (!inode)
{
ret = ENOTDIR;
goto errout_with_direntry;
}
ret = ENOTDIR;
goto errout_with_direntry;
}
/* It looks we have a valid psuedo-filesystem node. Take two references
* on the inode -- one for the parent (fd_root) and one for the child (fd_next).
* Note that we do not call inode_addref because we are holding
* the tree semaphore and that would result in deadlock.
*/
/* It looks we have a valid psuedo-filesystem directory node. */
inode->i_crefs += 2;
dir->u.psuedo.fd_next = inode; /* This is the next node to use for readdir() */
/* Flag the inode as belonging to the psuedo-filesystem */
#ifndef CONFIG_DISABLE_MOUNTPOINT
DIRENT_SETPSUEDONODE(dir->fd_flags);
#endif
open_pseudodir(inode, dir);
}
inode_semgive();
@ -242,7 +310,7 @@ errout_with_direntry:
errout_with_semaphore:
inode_semgive();
*get_errno_ptr() = ret;
errno = ret;
return NULL;
}