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- /****************************************************************************
- * fs/dirent/fs_opendir.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 <stdbool.h>
- #include <string.h>
- #include <dirent.h>
- #include <assert.h>
- #include <errno.h>
- #include <nuttx/kmalloc.h>
- #include <nuttx/fs/fs.h>
- #include <nuttx/fs/dirent.h>
- #include "inode/inode.h"
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: open_mountpoint
- *
- * Description:
- * Handle the case where the inode to be opened is within a mountpoint.
- *
- * Input Parameters:
- * inode -- the inode of the mountpoint to open
- * relpath -- the relative path within the mountpoint to open
- * dir -- the dirent structure to be initialized
- *
- * Returned Value:
- * 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. 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.
- *
- * Input Parameters:
- * inode -- the inode of the mountpoint to open
- * dir -- the dirent structure to be initialized
- *
- * Returned Value:
- * None
- *
- ****************************************************************************/
- static void open_pseudodir(FAR struct inode *inode,
- FAR struct fs_dirent_s *dir)
- {
- /* We have a valid pseudo-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->fd_root = inode; /* Save the inode where we start */
- dir->u.pseudo.fd_next = inode; /* This is the next node to use for readdir() */
- /* Flag the inode as belonging to the pseudo-filesystem */
- #ifndef CONFIG_DISABLE_MOUNTPOINT
- DIRENT_SETPSEUDONODE(dir->fd_flags);
- #endif
- }
- /****************************************************************************
- * Name: open_emptydir
- *
- * Description:
- * Handle the case where the inode to be opened is an empty, directory node
- * within the top-level pseudo-file system. That is, it has no operations
- * and, therefore, it must be a directory node. But is has no children
- * to be enumerated either.
- *
- * Input Parameters:
- * dir -- the dirent structure to be initialized
- *
- * Returned Value:
- * None
- *
- ****************************************************************************/
- static inline void open_emptydir(FAR struct fs_dirent_s *dir)
- {
- /* We have a valid, but empty pseudo-filesystem node. fd_next is NULL
- * meaning that we are already at the end of the list of its children.
- * fd_root is NULL so that if the directory is rewound, it will still be
- * at the end of the list.
- */
- #if 0 /* Already nullified by kumm_zalloc */
- dir->fd_root = NULL; /* Save the inode where we start */
- dir->u.pseudo.fd_next = NULL; /* We are at the end of the list */
- #endif
- /* Flag the inode as belonging to the pseudo-filesystem */
- #ifndef CONFIG_DISABLE_MOUNTPOINT
- DIRENT_SETPSEUDONODE(dir->fd_flags);
- #endif
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * 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.
- *
- * Input Parameters:
- * path -- the directory to open
- *
- * Returned Value:
- * 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.
- * ENFILE - Too many files are currently open in the
- * system.
- * ENOENT - Directory does not exist, or name is an empty
- * string.
- * ENOMEM - Insufficient memory to complete the operation.
- * ENOTDIR - 'path' is not a directory.
- *
- ****************************************************************************/
- FAR DIR *opendir(FAR const char *path)
- {
- FAR struct inode *inode = NULL;
- FAR struct fs_dirent_s *dir;
- struct inode_search_s desc;
- #ifndef CONFIG_DISABLE_MOUNTPOINT
- FAR const char *relpath = NULL;
- #endif
- int ret;
- /* If we are given 'nothing' then we will interpret this as
- * request for the root inode.
- */
- SETUP_SEARCH(&desc, path, false);
- ret = inode_semtake();
- if (ret < 0)
- {
- ret = -ret;
- goto errout;
- }
- /* Find the node matching the path. */
- ret = inode_search(&desc);
- if (ret >= 0)
- {
- inode = desc.node;
- DEBUGASSERT(inode != NULL);
- #ifndef CONFIG_DISABLE_MOUNTPOINT
- relpath = desc.relpath;
- #endif
- }
- /* Did we get an inode? */
- if (inode == NULL)
- {
- /* Inode for 'path' does not exist. */
- ret = ENOTDIR;
- goto errout_with_semaphore;
- }
- /* Allocate a type DIR -- which is little more than an inode
- * container.
- */
- dir = (FAR struct fs_dirent_s *)kumm_zalloc(sizeof(struct fs_dirent_s));
- if (!dir)
- {
- /* Insufficient memory to complete the operation. */
- ret = ENOMEM;
- goto errout_with_semaphore;
- }
- /* Populate the DIR structure and return it to the caller. The way that
- * we do this depends on whenever this is a "normal" pseudo-file-system
- * inode or a file system mountpoint.
- */
- dir->fd_position = 0; /* This is the position in the read stream */
- /* Is this a node in the pseudo filesystem? Or a mountpoint? */
- #ifndef CONFIG_DISABLE_MOUNTPOINT
- if (INODE_IS_MOUNTPT(inode))
- {
- /* Yes, the node is a file system mountpoint */
- dir->fd_root = inode; /* Save the inode where we start */
- /* Open the directory at the relative path */
- ret = open_mountpoint(inode, relpath, dir);
- if (ret != OK)
- {
- goto errout_with_direntry;
- }
- }
- else
- #endif
- {
- /* The node is part of the root pseudo 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.
- */
- FAR struct inode *child = inode->i_child;
- if (child != NULL)
- {
- /* It looks we have a valid pseudo-filesystem directory node. */
- open_pseudodir(child, dir);
- }
- else if (!inode->u.i_ops)
- {
- /* This is a dangling node with no children and no operations. Set
- * up to enumerate an empty directory.
- */
- open_emptydir(dir);
- }
- else
- {
- ret = ENOTDIR;
- goto errout_with_direntry;
- }
- }
- RELEASE_SEARCH(&desc);
- inode_semgive();
- return ((FAR DIR *)dir);
- /* Nasty goto's make error handling simpler */
- errout_with_direntry:
- kumm_free(dir);
- errout_with_semaphore:
- RELEASE_SEARCH(&desc);
- inode_semgive();
- errout:
- set_errno(ret);
- return NULL;
- }
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