313 lines
9.4 KiB
C
313 lines
9.4 KiB
C
/****************************************************************************
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* fs/fs_opendir.c
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*
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* Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdbool.h>
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#include <dirent.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/fs/dirent.h>
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#include "fs_internal.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: open_mountpoint
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*
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* Description:
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* Handle the case where the inode to be opened is within a mountpoint.
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*
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* Inputs:
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* inode -- the inode of the mountpoint to open
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* relpath -- the relative path within the mountpoint to open
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* dir -- the dirent structure to be initialized
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*
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* Return:
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* On success, OK is returned; Otherwise, a positive errno is returned.
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*
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****************************************************************************/
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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static inline int open_mountpoint(FAR struct inode *inode,
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FAR const char *relpath,
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FAR struct fs_dirent_s *dir)
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{
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int ret;
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/* The inode itself as the 'root' of mounted volume. The actually
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* directory is at relpath into the* mounted filesystem.
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*
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* Verify that the mountpoint inode supports the opendir() method
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*/
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if (!inode->u.i_mops || !inode->u.i_mops->opendir)
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{
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return ENOSYS;
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}
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/* Take reference to the mountpoint inode (fd_root). Note that we do
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* not use inode_addref() because we already hold the tree semaphore.
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*/
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inode->i_crefs++;
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/* Perform the opendir() operation */
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ret = inode->u.i_mops->opendir(inode, relpath, dir);
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if (ret < 0)
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{
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/* We now need to back off our reference to the inode. We can't
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* call inode_release() to do that unless we release the tree
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* semaphore. The following should be safe because: (1) after the
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* reference count was incremented above it should be >=1 so it should
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* not decrement below zero, and (2) we hold the tree semaphore so no
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* other thread should be able to change the reference count.
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*/
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inode->i_crefs--;
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DEBUGASSERT(inode->i_crefs >= 0);
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/* Negate the error value so that it can be used to set errno */
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return -ret;
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Name: open_pseudodir
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*
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* Description:
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* Handle the case where the inode to be opened is within the top-level
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* pseudo-file system.
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*
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* Inputs:
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* inode -- the inode of the mountpoint to open
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* dir -- the dirent structure to be initialized
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*
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* Return:
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* On success, OK is returned; Otherwise, a positive errno is returned.
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*
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****************************************************************************/
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static void open_pseudodir(FAR struct inode *inode, FAR struct fs_dirent_s *dir)
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{
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/* We have a valid pseudo-filesystem node. Take two references on the
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* inode -- one for the parent (fd_root) and one for the child (fd_next).
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* Note that we do not call inode_addref because we are holding the tree
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* semaphore and that would result in deadlock.
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*/
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inode->i_crefs += 2;
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dir->u.pseudo.fd_next = inode; /* This is the next node to use for readdir() */
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/* Flag the inode as belonging to the pseudo-filesystem */
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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DIRENT_SETPSEUDONODE(dir->fd_flags);
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#endif
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: opendir
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*
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* Description:
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* The opendir() function opens a directory stream corresponding to the
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* directory name, and returns a pointer to the directory stream. The
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* stream is positioned at the first entry in the directory.
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*
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* Inputs:
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* path -- the directory to open
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*
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* Return:
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* The opendir() function returns a pointer to the directory stream. On
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* error, NULL is returned, and errno is set appropriately.
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*
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* EACCES - Permission denied.
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* EMFILE - Too many file descriptors in use by process.
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* ENFILE - Too many files are currently open in the
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* system.
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* ENOENT - Directory does not exist, or name is an empty
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* string.
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* ENOMEM - Insufficient memory to complete the operation.
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* ENOTDIR - 'path' is not a directory.
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*
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****************************************************************************/
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FAR DIR *opendir(FAR const char *path)
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{
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FAR struct inode *inode = NULL;
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FAR struct fs_dirent_s *dir;
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FAR const char *relpath;
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bool bisroot = false;
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int ret;
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/* If we are given 'nothing' then we will interpret this as
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* request for the root inode.
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*/
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inode_semtake();
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if (!path || *path == 0 || strcmp(path, "/") == 0)
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{
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inode = root_inode;
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bisroot = true;
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relpath = NULL;
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}
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else
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{
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/* We don't know what to do with relative pathes */
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if (*path != '/')
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{
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ret = -ENOTDIR;
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goto errout_with_semaphore;
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}
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/* Find the node matching the path. */
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inode = inode_search(&path, (FAR struct inode**)NULL, (FAR struct inode**)NULL, &relpath);
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}
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/* Did we get an inode? */
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if (!inode)
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{
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/* 'path' is not a does not exist.*/
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ret = ENOTDIR;
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goto errout_with_semaphore;
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}
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/* Allocate a type DIR -- which is little more than an inode
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* container.
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*/
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dir = (FAR struct fs_dirent_s *)kzalloc(sizeof(struct fs_dirent_s));
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if (!dir)
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{
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/* Insufficient memory to complete the operation.*/
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ret = ENOMEM;
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goto errout_with_semaphore;
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}
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/* Populate the DIR structure and return it to the caller. The way that
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* we do this depends on whenever this is a "normal" pseudo-file-system
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* inode or a file system mountpoint.
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*/
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dir->fd_root = inode; /* Save the inode where we start */
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dir->fd_position = 0; /* This is the position in the read stream */
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/* First, handle the special case of the root inode. This must be
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* special-cased here because the root inode might ALSO be a mountpoint.
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*/
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if (bisroot)
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{
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/* Whatever payload the root inode carries, the root inode is always
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* a directory inode in the pseudo-file system
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*/
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open_pseudodir(inode, dir);
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}
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/* Is this a node in the pseudo filesystem? Or a mountpoint? If the node
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* is the root (bisroot == TRUE), then this is a special case.
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*/
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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else if (INODE_IS_MOUNTPT(inode))
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{
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/* Yes, the node is a file system mointpoint. */
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ret = open_mountpoint(inode, relpath, dir);
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if (ret != OK)
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{
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goto errout_with_direntry;
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}
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}
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#endif
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else
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{
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/* The node is part of the root pseudo file system. Does the inode have a child?
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* If so that the child would be the 'root' of a list of nodes under
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* the directory.
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*/
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inode = inode->i_child;
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if (!inode)
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{
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ret = ENOTDIR;
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goto errout_with_direntry;
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}
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/* It looks we have a valid pseudo-filesystem directory node. */
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open_pseudodir(inode, dir);
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}
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inode_semgive();
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return ((DIR*)dir);
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/* Nasty goto's make error handling simpler */
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errout_with_direntry:
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kfree(dir);
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errout_with_semaphore:
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inode_semgive();
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set_errno(ret);
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return NULL;
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}
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