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px4-firmware/nuttx/fs/fs_files.c

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/****************************************************************************
* fs/fs_files.c
*
* Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <string.h>
#include <semaphore.h>
#include <assert.h>
#include <sched.h>
#include <errno.h>
#include <nuttx/fs/fs.h>
#include <nuttx/kmalloc.h>
#include "fs_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: _files_semtake
****************************************************************************/
static void _files_semtake(FAR struct filelist *list)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(&list->fl_sem) != 0)
{
/* The only case that an error should occr here is if
* the wait was awakened by a signal.
*/
ASSERT(get_errno() == EINTR);
}
}
/****************************************************************************
* Name: _files_semgive
****************************************************************************/
#define _files_semgive(list) sem_post(&list->fl_sem)
/****************************************************************************
* Name: _files_close
*
* Description:
* Close an inode (if open)
*
* Assumuptions:
* Caller holds the list semaphore because the file descriptor will be freed.
*
****************************************************************************/
static int _files_close(FAR struct file *filep)
{
struct inode *inode = filep->f_inode;
int ret = OK;
/* Check if the struct file is open (i.e., assigned an inode) */
if (inode)
{
/* Close the file, driver, or mountpoint. */
if (inode->u.i_ops && inode->u.i_ops->close)
{
/* Perform the close operation */
ret = inode->u.i_ops->close(filep);
}
/* And release the inode */
inode_release(inode);
/* Release the file descriptor */
filep->f_oflags = 0;
filep->f_pos = 0;
filep->f_inode = NULL;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: files_initialize
*
* Description:
* This is called from the FS initialization logic to configure the files.
*
****************************************************************************/
void files_initialize(void)
{
}
/****************************************************************************
* Name: files_alloclist
*
* Description: Allocate a list of files for a new task
*
****************************************************************************/
FAR struct filelist *files_alloclist(void)
{
FAR struct filelist *list;
list = (FAR struct filelist*)kzalloc(sizeof(struct filelist));
if (list)
{
/* Start with a reference count of one */
list->fl_crefs = 1;
/* Initialize the list access mutex */
(void)sem_init(&list->fl_sem, 0, 1);
}
return list;
}
/****************************************************************************
* Name: files_addreflist
*
* Description:
* Increase the reference count on a file list
*
****************************************************************************/
int files_addreflist(FAR struct filelist *list)
{
if (list)
{
/* Increment the reference count on the list.
* NOTE: that we disable interrupts to do this
* (vs. taking the list semaphore). We do this
* because file cleanup operations often must be
* done from the IDLE task which cannot wait
* on semaphores.
*/
register irqstate_t flags = irqsave();
list->fl_crefs++;
irqrestore(flags);
}
return OK;
}
/****************************************************************************
* Name: files_releaselist
*
* Description:
* Release a reference to the file list
*
****************************************************************************/
int files_releaselist(FAR struct filelist *list)
{
int crefs;
if (list)
{
/* Decrement the reference count on the list.
* NOTE: that we disable interrupts to do this
* (vs. taking the list semaphore). We do this
* because file cleanup operations often must be
* done from the IDLE task which cannot wait
* on semaphores.
*/
register irqstate_t flags = irqsave();
crefs = --(list->fl_crefs);
irqrestore(flags);
/* If the count decrements to zero, then there is no reference
* to the structure and it should be deallocated. Since there
* are references, it would be an error if any task still held
* a reference to the list's semaphore.
*/
if (crefs <= 0)
{
int i;
/* Close each file descriptor .. Normally, you would need
* take the list semaphore, but it is safe to ignore the
* semaphore in this context because there are no references
*/
for (i = 0; i < CONFIG_NFILE_DESCRIPTORS; i++)
{
(void)_files_close(&list->fl_files[i]);
}
/* Destroy the semaphore and release the filelist */
(void)sem_destroy(&list->fl_sem);
sched_free(list);
}
}
return OK;
}
/****************************************************************************
* Name: files_dup
*
* Description:
* Assign an inode to a specific files structure. This is the heart of
* dup2.
*
****************************************************************************/
int files_dup(FAR struct file *filep1, FAR struct file *filep2)
{
FAR struct filelist *list;
FAR struct inode *inode;
int err;
int ret;
if (!filep1 || !filep1->f_inode || !filep2)
{
err = EBADF;
goto errout;
}
#ifndef CONFIG_DISABLE_MOUNTPOINT
if (INODE_IS_MOUNTPT(filep1->f_inode))
{
err = ENOSYS; /* Not yet supported */
goto errout;
}
#endif
list = sched_getfiles();
if (!list)
{
err = EMFILE;
goto errout;
}
_files_semtake(list);
/* If there is already an inode contained in the new file structure,
* close the file and release the inode.
*/
ret = _files_close(filep2);
if (ret < 0)
{
/* An error occurred while closing the driver */
goto errout_with_ret;
}
/* Increment the reference count on the contained inode */
inode = filep1->f_inode;
inode_addref(inode);
/* Then clone the file structure */
filep2->f_oflags = filep1->f_oflags;
filep2->f_pos = filep1->f_pos;
filep2->f_inode = inode;
/* Call the open method on the file, driver, mountpoint so that it
* can maintain the correct open counts.
*/
if (inode->u.i_ops && inode->u.i_ops->open)
{
#ifndef CONFIG_DISABLE_MOUNTPOINT
#if 0 /* Not implemented */
if (INODE_IS_MOUNTPT(inode))
{
/* Open a file on the mountpoint */
ret = inode->u.i_mops->open(filep2, ?, filep2->f_oflags, ?);
}
else
#endif
#endif
{
/* Open the pseudo file or device driver */
ret = inode->u.i_ops->open(filep2);
}
/* Handle open failures */
if (ret < 0)
{
goto errout_with_inode;
}
}
_files_semgive(list);
return OK;
/* Handler various error conditions */
errout_with_inode:
inode_release(filep2->f_inode);
filep2->f_oflags = 0;
filep2->f_pos = 0;
filep2->f_inode = NULL;
errout_with_ret:
err = -ret;
_files_semgive(list);
errout:
set_errno(err);
return ERROR;
}
/****************************************************************************
* Name: files_allocate
*
* Description:
* Allocate a struct files instance and associate it with an inode instance.
* Returns the file descriptor == index into the files array.
*
****************************************************************************/
int files_allocate(FAR struct inode *inode, int oflags, off_t pos, int minfd)
{
FAR struct filelist *list;
int i;
list = sched_getfiles();
if (list)
{
_files_semtake(list);
for (i = minfd; i < CONFIG_NFILE_DESCRIPTORS; i++)
{
if (!list->fl_files[i].f_inode)
{
list->fl_files[i].f_oflags = oflags;
list->fl_files[i].f_pos = pos;
list->fl_files[i].f_inode = inode;
_files_semgive(list);
return i;
}
}
_files_semgive(list);
}
return ERROR;
}
/****************************************************************************
* Name: files_close
*
* Description:
* Close an inode (if open)
*
* Assumuptions:
* Caller holds the list semaphore because the file descriptor will be freed.
*
****************************************************************************/
int files_close(int filedes)
{
FAR struct filelist *list;
int ret;
/* Get the thread-specific file list */
list = sched_getfiles();
if (!list)
{
return -EMFILE;
}
/* If the file was properly opened, there should be an inode assigned */
if (filedes < 0 || filedes >= CONFIG_NFILE_DESCRIPTORS || !list->fl_files[filedes].f_inode)
{
return -EBADF;
}
/* Perform the protected close operation */
_files_semtake(list);
ret = _files_close(&list->fl_files[filedes]);
_files_semgive(list);
return ret;
}
/****************************************************************************
* Name: files_release
*
* Assumuptions:
* Similar to files_close(). Called only from open() logic on error
* conditions.
*
****************************************************************************/
void files_release(int filedes)
{
FAR struct filelist *list;
list = sched_getfiles();
if (list)
{
if (filedes >=0 && filedes < CONFIG_NFILE_DESCRIPTORS)
{
_files_semtake(list);
list->fl_files[filedes].f_oflags = 0;
list->fl_files[filedes].f_pos = 0;
list->fl_files[filedes].f_inode = NULL;
_files_semgive(list);
}
}
}
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