/****************************************************************************
* fs/vfs/fs_read.c
*
* Copyright (C) 2007-2009, 2012-2014 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 <sys/socket.h>
#include <unistd.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>
#include "inode/inode.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_read
*
* Description:
* This is the internal implementation of read().
*
* Parameters:
* file File structure instance
* buf User-provided to save the data
* nbytes The maximum size of the user-provided buffer
*
* Return:
* The positive non-zero number of bytes read on success, 0 on if an
* end-of-file condition, or -1 on failure with errno set appropriately.
*
****************************************************************************/
ssize_t file_read(FAR struct file *filep, FAR void *buf, size_t nbytes)
{
FAR struct inode *inode;
int ret = -EBADF;
DEBUGASSERT(filep);
inode = filep->f_inode;
/* Was this file opened for read access? */
if ((filep->f_oflags & O_RDOK) == 0)
{
/* No.. File is not read-able */
ret = -EACCES;
}
/* Is a driver or mountpoint registered? If so, does it support the read
* method?
*/
else 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 being identical in
* signature and position in the operations vtable.
*/
ret = (int)inode->u.i_ops->read(filep, (char*)buf, (size_t)nbytes);
}
/* If an error occurred, set errno and return -1 (ERROR) */
if (ret < 0)
{
set_errno(-ret);
return ERROR;
}
/* Otherwise, return the number of bytes read */
return ret;
}
/****************************************************************************
* Name: read
*
* Description:
* The standard, POSIX read interface.
*
* Parameters:
* file File structure instance
* buf User-provided to save the data
* nbytes The maximum size of the user-provided buffer
*
* Return:
* The positive non-zero number of bytes read on success, 0 on if an
* end-of-file condition, or -1 on failure with errno set appropriately.
*
****************************************************************************/
ssize_t read(int fd, FAR void *buf, size_t nbytes)
{
/* Did we get a valid file descriptor? */
#if CONFIG_NFILE_DESCRIPTORS > 0
if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
#endif
{
/* No.. If networking is enabled, read() is the same as recv() with
* the flags parameter set to zero.
*/
#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
return recv(fd, buf, nbytes, 0);
#else
/* No networking... it is a bad descriptor in any event */
set_errno(EBADF);
return ERROR;
#endif
}
#if CONFIG_NFILE_DESCRIPTORS > 0
else
{
FAR struct file *filep;
/* The descriptor is in a valid range to file descriptor... do the
* read. First, get the file structure.
*/
filep = fs_getfilep(fd);
if (!filep)
{
/* The errno value has already been set */
return ERROR;
}
/* Then let file_read do all of the work */
return file_read(filep, buf, nbytes);
}
#endif
}
