332 lines
9.4 KiB
C
332 lines
9.4 KiB
C
/****************************************************************************
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* fs/fs_inode.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 <spudmonkey@racsa.co.cr>
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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 <assert.h>
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#include <semaphore.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 "fs_internal.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Variables
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****************************************************************************/
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static sem_t tree_sem;
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/****************************************************************************
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* Public Variables
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****************************************************************************/
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FAR struct inode *root_inode = NULL;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: _inode_compare
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****************************************************************************/
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static int _inode_compare(const char *fname,
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FAR struct inode *node)
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{
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char *nname = node->i_name;
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if (!nname)
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{
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return 1;
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}
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if (!fname)
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{
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return -1;
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}
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for (;;)
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{
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/* At end of node name? */
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if (!*nname)
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{
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/* Yes.. also end of find name? */
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if (!*fname || *fname == '/')
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{
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/* Yes.. return match */
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return 0;
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}
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else
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{
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/* No... return find name > node name */
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return 1;
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}
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}
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/* At end of find name?*/
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else if (!*fname || *fname == '/')
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{
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/* Yes... return find name < node name */
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return -1;
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}
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/* check for non-matching characters */
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else if (*fname > *nname)
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{
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return 1;
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}
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else if (*fname < *nname)
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{
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return -1;
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}
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/* Not at the end of either string and all of the
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* characters still match. keep looking.
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*/
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else
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{
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fname++;
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nname++;
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}
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}
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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: fs_initialize
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*
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* Description:
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* This is called from the OS initialization logic to configure
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* the file system.
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*
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****************************************************************************/
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void fs_initialize(void)
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{
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/* Initialize the semaphore to one (to support one-at-
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* a-time access to the inode tree).
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*/
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(void)sem_init(&tree_sem, 0, 1);
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/* Initialize files array (if it is used) */
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#ifdef CONFIG_HAVE_WEAKFUNCTIONS
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if (files_initialize != NULL)
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#endif
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{
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files_initialize();
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}
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}
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/****************************************************************************
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* Name: inode_semtake
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****************************************************************************/
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void inode_semtake(void)
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{
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/* Take the semaphore (perhaps waiting) */
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while (sem_wait(&tree_sem) != 0)
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{
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/* The only case that an error should occr here is if
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* the wait was awakened by a signal.
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*/
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ASSERT(errno == EINTR);
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}
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}
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/****************************************************************************
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* Name: inode_semgive
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****************************************************************************/
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void inode_semgive(void)
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{
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sem_post(&tree_sem);
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}
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/****************************************************************************
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* Name: inode_search
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*
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* Description:
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* Find the inode associated with 'path' returning the
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* inode references and references to its companion nodes.
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*
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* Assumptions:
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* The caller holds the tree_sem
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*
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****************************************************************************/
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FAR struct inode *inode_search(const char **path,
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FAR struct inode **peer,
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FAR struct inode **parent,
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const char **relpath)
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{
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const char *name = *path + 1; /* Skip over leading '/' */
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FAR struct inode *node = root_inode;
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FAR struct inode *left = NULL;
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FAR struct inode *above = NULL;
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while (node)
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{
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int result = _inode_compare(name, node);
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/* Case 1: The name is less than the name of the node.
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* Since the names are ordered, these means that there
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* is no peer node with this name and that there can be
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* no match in the fileystem.
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*/
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if (result < 0)
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{
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node = NULL;
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break;
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}
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/* Case 2: the name is greater than the name of the node.
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* In this case, the name may still be in the list to the
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* "right"
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*/
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else if (result > 0)
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{
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left = node;
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node = node->i_peer;
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}
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/* The names match */
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else
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{
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/* Now there are three more possibilities:
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* (1) This is the node that we are looking for or,
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* (2) The node we are looking for is "below" this one.
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* (3) This node is a mountpoint and will absorb all request
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* below this one
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*/
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name = inode_nextname(name);
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if (!*name || INODE_IS_MOUNTPT(node))
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{
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/* Either (1) we are at the end of the path, so this must be the
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* node we are looking for or else (2) this node is a mountpoint
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* and will handle the remaining part of the pathname
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*/
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if (relpath)
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{
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*relpath = name;
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}
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break;
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}
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else
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{
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/* More to go, keep looking at the next level "down" */
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above = node;
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left = NULL;
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node = node->i_child;
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}
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}
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}
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/* node is null. This can happen in one of four cases:
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* With node = NULL
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* (1) We went left past the final peer: The new node
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* name is larger than any existing node name at
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* that level.
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* (2) We broke out in the middle of the list of peers
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* because the name was not found in the ordered
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* list.
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* (3) We went down past the final parent: The new node
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* name is "deeper" than anything that we currently
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* have in the tree.
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* with node != NULL
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* (4) When the node matching the full path is found
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*/
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if (peer) *peer = left;
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if (parent) *parent = above;
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*path = name;
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return node;
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}
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/****************************************************************************
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* Name: inode_free
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****************************************************************************/
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void inode_free(FAR struct inode *node)
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{
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if (node)
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{
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inode_free(node->i_peer);
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inode_free(node->i_child);
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kfree(node);
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}
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}
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/****************************************************************************
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* Name: inode_nextname
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*
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* Description:
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* Given a path with node names separated by '/', return
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* the next node name.
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*
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****************************************************************************/
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const char *inode_nextname(const char *name)
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{
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while (*name && *name != '/') name++;
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if (*name) name++;
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return name;
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}
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