/****************************************************************************
* fs_read.c
*
* Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 <unistd.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>
#include "fs_internal.h"
/****************************************************************************
* Global Functions
****************************************************************************/
ssize_t read(int fd, FAR void *buf, size_t nbytes)
{
FAR struct filelist *list;
int ret = -EBADF;
/* Get the thread-specific file list */
list = sched_getfiles();
if (!list)
{
errno = EMFILE;
return ERROR;
}
/* Were we given a valid file descriptor? */
if ((unsigned int)fd < CONFIG_NFILE_DESCRIPTORS)
{
FAR struct file *this_file = &list->fl_files[fd];
/* Was this file opened for read access? */
if ((this_file->f_oflags & O_RDOK) != 0)
{
struct inode *inode = this_file->f_inode;
/* Is a driver or mountpoint registered? If so, does it support
* the read method?
*/
if (inode && inode->u.i_ops && inode->u.i_ops->read)
{
/* Yes, then let it perform the read. NOTE that for the case
* of the mountpoint, we depend on the read methods bing
* identical in signature and position in the operations vtable.
*/
ret = (int)inode->u.i_ops->read(this_file, (char*)buf, (size_t)nbytes);
}
}
}
/* If an error occurred, set errno and return -1 (ERROR) */
if (ret < 0)
{
errno = -ret;
return ERROR;
}
/* Otherwise, return the number of bytes read */
return ret;
}
