118 lines
3.8 KiB
C
118 lines
3.8 KiB
C
/************************************************************
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* fs_seekdir.c
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*
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* Copyright (C) 2007 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 Gregory Nutt 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 <sys/types.h>
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#include <dirent.h>
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#include <errno.h>
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#include <nuttx/fs.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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* Public Functions
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************************************************************/
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/************************************************************
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* Name: seekdir
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*
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* Description:
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* The seekdir() function sets the location in the
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* directory stream from which the next readdir() call will
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* start. seekdir() should be used with an offset returned
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* by telldir().
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*
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* Inputs:
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* dirp -- An instance of type DIR created by a previous
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* call to opendir();
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* offset -- offset to seek to
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*
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* Return:
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* None
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*
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************************************************************/
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#if CONFIG_NFILE_DESCRIPTORS > 0
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void seekdir(FAR DIR *dirp, off_t offset)
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{
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struct internal_dir_s *idir = (struct internal_dir_s *)dirp;
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struct inode *curr;
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struct inode *prev;
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off_t i;
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if (idir)
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{
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/* Traverse the peer list starting at the 'root' of the
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* the list until we find the node at 'offset". If devices
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* are being registered and unregistered, then this can
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* be a very unpredictable operation.
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*/
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inode_semtake();
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for (i = 0, curr = idir->root;
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curr && i != offset;
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i++, curr = curr->i_peer);
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/* Now get the inode to vist next time that readdir() is called */
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prev = idir->next;
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idir->next = curr; /* The next node to visit */
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if (curr)
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{
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/* Increment the reference count on this next node */
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curr->i_crefs++;
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}
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inode_semgive();
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if (prev)
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{
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inode_release(prev);
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}
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}
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}
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#endif /* CONFIG_NFILE_DESCRIPTORS */
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