148 lines
4.5 KiB
C
148 lines
4.5 KiB
C
/****************************************************************************
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* fs/inode/fs_filedetach.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <errno.h>
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#include <nuttx/sched.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/semaphore.h>
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#include "inode/inode.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: _files_semtake
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****************************************************************************/
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static inline int _files_semtake(FAR struct filelist *list)
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{
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return nxsem_wait_uninterruptible(&list->fl_sem);
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}
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/****************************************************************************
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* Name: _files_semgive
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****************************************************************************/
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#define _files_semgive(list) nxsem_post(&list->fl_sem)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: file_detach
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*
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* Description:
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* This function is used in device drivers to create a task-independent
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* handle to an entity in the file system. file_detach() duplicates the
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* 'struct file' that underlies the file descriptor, then closes the file
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* descriptor.
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*
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* This function will fail if fd is not a valid file descriptor. In
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* particular, it will fail if fd is a socket descriptor.
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*
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* Input Parameters:
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* fd - The file descriptor to be detached. This descriptor will be
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* closed and invalid if the file was successfully detached.
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* filep - A pointer to a user provided memory location in which to
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* received the duplicated, detached file structure.
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*
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* Returned Value:
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* Zero (OK) is returned on success; A negated errno value is returned on
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* any failure to indicate the nature of the failure.
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*
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****************************************************************************/
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int file_detach(int fd, FAR struct file *filep)
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{
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FAR struct filelist *list;
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FAR struct file *parent;
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int ret;
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DEBUGASSERT(filep != NULL);
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/* Verify the file descriptor range */
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if (fd < 0 || fd >= CONFIG_NFILE_DESCRIPTORS)
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{
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/* Not a file descriptor (might be a socket descriptor) */
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return -EBADF;
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}
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/* Get the thread-specific file list. It should never be NULL in this
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* context.
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*/
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list = nxsched_get_files();
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DEBUGASSERT(list != NULL);
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/* If the file was properly opened, there should be an inode assigned */
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ret = _files_semtake(list);
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if (ret < 0)
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{
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/* Probably canceled */
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return ret;
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}
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parent = &list->fl_files[fd];
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if (parent->f_inode == NULL)
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{
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/* File is not open */
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_files_semgive(list);
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return -EBADF;
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}
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/* Duplicate the 'struct file' content into the user-provided file
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* structure.
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*/
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filep->f_oflags = parent->f_oflags;
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filep->f_pos = parent->f_pos;
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filep->f_inode = parent->f_inode;
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filep->f_priv = parent->f_priv;
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/* Release the file descriptor *without* calling the driver close method
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* and without decrementing the inode reference count. That will be done
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* in file_close().
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*/
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parent->f_oflags = 0;
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parent->f_pos = 0;
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parent->f_inode = NULL;
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parent->f_priv = NULL;
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_files_semgive(list);
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return OK;
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}
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