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px4-firmware/nuttx/fs/fs_fdopen.c

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/****************************************************************************
* fs/fs_fdopen.c
*
* Copyright (C) 2007-2012 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 <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <fcntl.h>
#include <errno.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/net/net.h>
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: fs_checkfd
*
* Description:
* Check if the file descriptor is valid for the provided TCB and if it
* supports the requested access.
*
****************************************************************************/
#if CONFIG_NFILE_DESCRIPTORS > 0
static inline int fs_checkfd(FAR _TCB *tcb, int fd, int oflags)
{
FAR struct filelist *flist;
FAR struct inode *inode;
/* Get the file list from the TCB */
flist = tcb->filelist;
/* Get the inode associated with the file descriptor. This should
* normally be the case if fd >= 0. But not in the case where the
* called attempts to explictly stdin with fdopen(0) but stdin has
* been closed.
*/
inode = flist->fl_files[fd].f_inode;
if (!inode)
{
/* No inode -- descriptor does not correspond to an open file */
return -ENOENT;
}
/* Make sure that the inode supports the requested access. In
* the case of fdopen, we are not actually creating the file -- in
* particular w and w+ do not truncate the file and any files have
* already been created.
*/
if (inode_checkflags(inode, oflags) != OK)
{
/* Cannot support the requested access */
return -EACCES;
}
/* Looks good to me */
return OK;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fs_fdopen
*
* Description:
* This function does the core operations for fopen and fdopen.
*
****************************************************************************/
FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR _TCB *tcb)
{
FAR struct streamlist *slist;
FAR FILE *stream;
int err = OK;
int ret;
int i;
/* Check input parameters */
if (fd < 0)
{
err = EBADF;
goto errout;
}
/* A NULL TCB pointer means to use this threads TCB. This is a little
* hack the let's this function be called from user-space (via a syscall)
* without having access to the TCB.
*/
if (!tcb)
{
tcb = sched_self();
}
/* Verify that this is a valid file/socket descriptor and that the
* requested access can be support.
*
* Is this fd in the range of valid file descriptors? Socket descriptors
* lie in a different range.
*/
#if CONFIG_NFILE_DESCRIPTORS > 0
if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
#endif
{
/* No.. If networking is enabled then this might be a socket
* descriptor.
*/
#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
ret = net_checksd(fd, oflags);
#else
/* No networking... it is just a bad descriptor */
err = EBADF;
goto errout;
#endif
}
/* The descriptor is in a valid range to file descriptor... perform some more checks */
#if CONFIG_NFILE_DESCRIPTORS > 0
else
{
ret = fs_checkfd(tcb, fd, oflags);
}
#endif
/* Do we have a good descriptor of some sort? */
if (ret < 0)
{
/* No... return the reported error */
err = -ret;
goto errout;
}
/* Get the stream list from the TCB */
slist = tcb->streams;
/* Find an unallocated FILE structure in the stream list */
ret = sem_wait(&slist->sl_sem);
if (ret != OK)
{
goto errout_with_errno;
}
for (i = 0 ; i < CONFIG_NFILE_STREAMS; i++)
{
stream = &slist->sl_streams[i];
if (stream->fs_filedes < 0)
{
/* Zero the structure */
#if CONFIG_STDIO_BUFFER_SIZE > 0
memset(stream, 0, sizeof(FILE));
#elif CONFIG_NUNGET_CHARS > 0
stream->fs_nungotten = 0;
#endif
#if CONFIG_STDIO_BUFFER_SIZE > 0
/* Initialize the semaphore the manages access to the buffer */
(void)sem_init(&stream->fs_sem, 0, 1);
/* Allocate the IO buffer */
stream->fs_bufstart = kmalloc(CONFIG_STDIO_BUFFER_SIZE);
if (!stream)
{
err = ENOMEM;
goto errout_with_sem;
}
/* Set up pointers */
stream->fs_bufend = &stream->fs_bufstart[CONFIG_STDIO_BUFFER_SIZE];
stream->fs_bufpos = stream->fs_bufstart;
stream->fs_bufpos = stream->fs_bufstart;
stream->fs_bufread = stream->fs_bufstart;
#endif
/* Save the file description and open flags. Setting the
* file descriptor locks this stream.
*/
stream->fs_filedes = fd;
stream->fs_oflags = (uint16_t)oflags;
sem_post(&slist->sl_sem);
return stream;
}
}
/* No free stream available.. report ENFILE */
err = ENFILE;
#if CONFIG_STDIO_BUFFER_SIZE > 0
errout_with_sem:
#endif
sem_post(&slist->sl_sem);
errout:
set_errno(err);
errout_with_errno:
return NULL;
}
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