nuttx/libs/libc/stdio/lib_libfwrite.c
anjiahao e0c3bf64a0 libc:Optimize the behavior of fwrite
Signed-off-by: anjiahao <anjiahao@xiaomi.com>
2022-06-07 22:28:00 +08:00

182 lines
4.5 KiB
C

/****************************************************************************
* libs/libc/stdio/lib_libfwrite.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <nuttx/fs/fs.h>
#include "libc.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: lib_fwrite
****************************************************************************/
ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream)
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
{
FAR const unsigned char *start = ptr;
FAR const unsigned char *src = ptr;
ssize_t ret = ERROR;
size_t gulp_size;
/* Make sure that writing to this stream is allowed */
if (stream == NULL)
{
set_errno(EBADF);
return ret;
}
/* Check if write access is permitted */
if ((stream->fs_oflags & O_WROK) == 0)
{
set_errno(EBADF);
goto errout;
}
/* If there is no I/O buffer, then output data immediately */
if (stream->fs_bufstart == NULL)
{
ret = _NX_WRITE(stream->fs_fd, ptr, count);
if (ret < 0)
{
_NX_SETERRNO(ret);
ret = ERROR;
}
goto errout;
}
/* Get exclusive access to the stream */
lib_take_semaphore(stream);
/* If the buffer is currently being used for read access, then
* discard all of the read-ahead data. We do not support concurrent
* buffered read/write access.
*/
if (lib_rdflush(stream) < 0)
{
goto errout_with_semaphore;
}
/* Determine the number of bytes left in the buffer */
gulp_size = stream->fs_bufend - stream->fs_bufpos;
if (gulp_size != CONFIG_STDIO_BUFFER_SIZE || count < gulp_size)
{
if (gulp_size > count)
{
/* Yes, clip the gulp to the size of the user data */
gulp_size = count;
}
/* Adjust the number of bytes remaining to be transferred
* on the next pass through the loop (might be zero).
*/
count -= gulp_size;
/* Transfer the data into the buffer */
memcpy(stream->fs_bufpos, src, gulp_size);
stream->fs_bufpos += gulp_size;
src += gulp_size;
/* Is the buffer full? */
if (stream->fs_bufpos >= stream->fs_bufend)
{
/* Flush the buffered data to the IO stream */
int bytes_buffered = lib_fflush(stream, false);
if (bytes_buffered < 0)
{
goto errout_with_semaphore;
}
}
}
if (count >= CONFIG_STDIO_BUFFER_SIZE)
{
ret = _NX_WRITE(stream->fs_fd, src, count);
if (ret < 0)
{
_NX_SETERRNO(ret);
ret = ERROR;
goto errout_with_semaphore;
}
src += ret;
}
else if (count > 0)
{
memcpy(stream->fs_bufpos, src, count);
stream->fs_bufpos += count;
src += count;
}
/* Return the number of bytes written */
ret = (uintptr_t)src - (uintptr_t)start;
errout_with_semaphore:
lib_give_semaphore(stream);
errout:
if (ret < 0)
{
stream->fs_flags |= __FS_FLAG_ERROR;
}
return ret;
}
#else
{
ssize_t ret = _NX_WRITE(stream->fs_fd, ptr, count);
if (ret < 0)
{
stream->fs_flags |= __FS_FLAG_ERROR;
_NX_SETERRNO(ret);
}
return ret;
}
#endif /* CONFIG_STDIO_DISABLE_BUFFERING */