312 lines
10 KiB
C
312 lines
10 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_libfread.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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>
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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 <assert.h>
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#include <errno.h>
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#include <nuttx/fs/fs.h>
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#include "libc.h"
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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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FAR unsigned char *dest = (FAR unsigned char *)ptr;
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ssize_t bytes_read;
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size_t remaining = count;
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#ifndef CONFIG_STDIO_DISABLE_BUFFERING
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int ret;
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#endif
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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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_NX_SETERRNO(EBADF);
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return ERROR;
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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 && remaining > 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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remaining--;
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}
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#endif
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#ifndef CONFIG_STDIO_DISABLE_BUFFERING
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/* Is there an I/O buffer? */
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if (stream->fs_bufstart != NULL)
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{
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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
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* concurrent 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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if (count - remaining > 0)
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{
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goto shortread;
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}
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else
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{
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_NX_SETERRNO(ret);
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goto errout_with_errno;
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}
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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 (remaining > 0)
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{
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/* Is there readable data in the buffer? */
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while (remaining > 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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remaining--;
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}
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/* The buffer is empty OR we have already supplied the number
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* of 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 (remaining > 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
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* file
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*/
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/* Mark the buffer empty */
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stream->fs_bufpos = stream->fs_bufread =
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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 (remaining > buffer_available)
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{
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bytes_read = _NX_READ(stream->fs_fd, dest, remaining);
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if (bytes_read < 0)
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{
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if (count - remaining > 0)
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{
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goto shortread;
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}
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else
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{
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/* An error occurred on the read. */
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_NX_SETERRNO(bytes_read);
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goto errout_with_errno;
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}
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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. But we may
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* already have buffered data. In that case,
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* we will report the EOF indication later.
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*/
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goto shortread;
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}
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else
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{
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/* Some (perhaps all) bytes were read. Adjust the
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* dest pointer and remaining bytes to be read.
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*/
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DEBUGASSERT(bytes_read <= remaining);
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dest += bytes_read;
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remaining -= bytes_read;
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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 = _NX_READ(stream->fs_fd,
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stream->fs_bufread,
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buffer_available);
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if (bytes_read < 0)
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{
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if (count - remaining > 0)
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{
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goto shortread;
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}
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else
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{
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/* An error occurred on the read. The error
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* code is in the 'errno' variable.
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*/
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_NX_SETERRNO(bytes_read);
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goto errout_with_errno;
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}
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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. But we may
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* already have buffered data. In that case,
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* we will report the EOF indication later.
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*/
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goto shortread;
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}
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else
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{
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/* Some (perhaps all) 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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}
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else
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#endif
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{
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/* Now get any other needed chars from the file. */
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while (remaining > 0)
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{
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bytes_read = _NX_READ(stream->fs_fd, dest, remaining);
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if (bytes_read < 0)
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{
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if (count - remaining > 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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/* 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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_NX_SETERRNO(bytes_read);
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goto errout_with_errno;
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}
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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. But we may already
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* have buffered data. In that case, we will report
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* the EOF indication later.
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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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DEBUGASSERT(bytes_read <= remaining);
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dest += bytes_read;
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remaining -= bytes_read;
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}
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}
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}
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#ifndef CONFIG_STDIO_DISABLE_BUFFERING
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/* Here after a successful (but perhaps short) read. A short read can
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* only occur is read() returns 0 (end-of-file).
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*/
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shortread:
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#endif
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/* Set or clear the EOF indicator. If we get here because of a
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* short read and the total number of bytes read is zero, then
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* we must be at the end-of-file.
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*/
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if (remaining == 0)
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{
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stream->fs_flags &= ~__FS_FLAG_EOF;
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}
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else
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{
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stream->fs_flags |= __FS_FLAG_EOF;
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}
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lib_give_semaphore(stream);
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return count - remaining;
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}
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/* Error exits */
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errout_with_errno:
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stream->fs_flags |= __FS_FLAG_ERROR;
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lib_give_semaphore(stream);
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return ERROR;
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}
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