100 lines
3.5 KiB
C
100 lines
3.5 KiB
C
/****************************************************************************
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* fs_read.c
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*
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* Copyright (C) 2007 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name Gregory Nutt nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Compilation Switches
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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 <sys/types.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sched.h>
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#include <errno.h>
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#include "fs_internal.h"
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/****************************************************************************
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* Global Functions
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****************************************************************************/
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int read(int fd, void *buf, unsigned int nbytes)
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{
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FAR struct filelist *list;
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int ret = EBADF;
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/* Get the thread-specific file list */
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list = sched_getfiles();
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if (!list)
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{
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*get_errno_ptr() = EMFILE;
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return ERROR;
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}
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/* Were we given a valid file descriptor? */
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if ((unsigned int)fd < CONFIG_NFILE_DESCRIPTORS)
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{
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FAR struct file *this_file = &list->fl_files[fd];
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/* Was this file opened for read access? */
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if ((this_file->f_oflags & O_RDOK) != 0)
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{
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struct inode *inode = this_file->f_inode;
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/* Is a driver or mountpoint registered? If so, does it support
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* the read method?
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*/
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if (inode && inode->u.i_ops && inode->u.i_ops->read)
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{
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/* Yes, then let it perform the read. NOTE that for the case
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* of the mountpoint, we depend on the read methods bing
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* identical in signature and position in the operations vtable.
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*/
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ret = (int)inode->u.i_ops->read(this_file, (char*)buf, (size_t)nbytes);
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}
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}
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}
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return ret;
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}
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