forked from Archive/PX4-Autopilot
291 lines
9.4 KiB
C
291 lines
9.4 KiB
C
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/****************************************************************************
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* lib/stdio/lib_libfread.c
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*
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* Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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 NuttX 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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* Included Files
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****************************************************************************/
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#include <nuttx/config.h> /* for CONFIG_STDIO_BUFFER_SIZE */
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#include <sys/types.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "lib_internal.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Global Constant Data
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****************************************************************************/
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/****************************************************************************
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* Global Variables
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****************************************************************************/
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/****************************************************************************
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* Private Constant Data
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****************************************************************************/
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/****************************************************************************
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* Private Variables
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: lib_fread
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****************************************************************************/
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ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
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{
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unsigned char *dest = (unsigned char*)ptr;
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ssize_t bytes_read;
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int ret;
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/* Make sure that reading from this stream is allowed */
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if (!stream || (stream->fs_oflags & O_RDOK) == 0)
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{
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set_errno(EBADF);
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bytes_read = -1;
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}
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else
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{
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/* The stream must be stable until we complete the read */
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lib_take_semaphore(stream);
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#if CONFIG_NUNGET_CHARS > 0
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/* First, re-read any previously ungotten characters */
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while ((stream->fs_nungotten > 0) && (count > 0))
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{
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/* Decrement the count of ungotten bytes to get an index */
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stream->fs_nungotten--;
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/* Return the last ungotten byte */
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*dest++ = stream->fs_ungotten[stream->fs_nungotten];
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/* That's one less byte that we have to read */
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count--;
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}
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#endif
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#if CONFIG_STDIO_BUFFER_SIZE > 0
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/* If the buffer is currently being used for write access, then
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* flush all of the buffered write data. We do not support concurrent
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* buffered read/write access.
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*/
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ret = lib_wrflush(stream);
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if (ret < 0)
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{
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lib_give_semaphore(stream);
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return ret;
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}
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/* Now get any other needed chars from the buffer or the file. */
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while (count > 0)
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{
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/* Is there readable data in the buffer? */
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while ((count > 0) && (stream->fs_bufpos < stream->fs_bufread))
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{
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/* Yes, copy a byte into the user buffer */
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*dest++ = *stream->fs_bufpos++;
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count--;
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}
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/* The buffer is empty OR we have already supplied the number of
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* bytes requested in the read. Check if we need to read
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* more from the file.
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*/
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if (count > 0)
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{
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size_t buffer_available;
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/* We need to read more data into the buffer from the file */
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/* Mark the buffer empty */
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stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart;
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/* How much space is available in the buffer? */
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buffer_available = stream->fs_bufend - stream->fs_bufread;
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/* Will the number of bytes that we need to read fit into
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* the buffer space that is available? If the read size is
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* larger than the buffer, then read some of the data
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* directly into the user's buffer.
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*/
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if (count > buffer_available)
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{
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bytes_read = read(stream->fs_filedes, dest, count);
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if (bytes_read < 0)
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{
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/* An error occurred on the read. The error code is
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* in the 'errno' variable.
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*/
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goto errout_with_errno;
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}
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else if (bytes_read == 0)
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{
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/* We are at the end of the file */
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goto shortread;
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}
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else
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{
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/* Some bytes were read. Adjust the dest pointer */
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dest += bytes_read;
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/* Were all of the requested bytes read? */
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if (bytes_read < count)
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{
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/* No. We must be at the end of file. */
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goto shortread;
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}
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else
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{
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/* Yes. We are done. */
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count = 0;
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}
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}
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}
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else
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{
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/* The number of bytes required to satisfy the read
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* is less than or equal to the size of the buffer
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* space that we have left. Read as much as we can
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* into the buffer.
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*/
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bytes_read = read(stream->fs_filedes, stream->fs_bufread, buffer_available);
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if (bytes_read < 0)
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{
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/* An error occurred on the read. The error code is
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* in the 'errno' variable.
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*/
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goto errout_with_errno;
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}
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else if (bytes_read == 0)
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{
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/* We are at the end of the file */
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goto shortread;
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}
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else
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{
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/* Some bytes were read */
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stream->fs_bufread += bytes_read;
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}
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}
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}
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}
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#else
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/* Now get any other needed chars from the file. */
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while (count > 0)
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{
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bytes_read = read(stream->fs_filedes, dest, count);
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if (bytes_read < 0)
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{
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/* An error occurred on the read. The error code is
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* in the 'errno' variable.
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*/
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goto errout_with_errno;
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}
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else if (bytes_read == 0)
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{
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break;
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}
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else
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{
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dest += bytes_read;
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count -= bytes_read;
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}
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}
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#endif
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/* Here after a successful (but perhaps short) read */
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#if CONFIG_STDIO_BUFFER_SIZE > 0
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shortread:
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#endif
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bytes_read = dest - (unsigned char*)ptr;
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}
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lib_give_semaphore(stream);
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return bytes_read;
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/* Error exits */
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errout_with_errno:
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lib_give_semaphore(stream);
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return -get_errno();
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}
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