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diff --git a/nuttx/libc/stdio/lib_libfwrite.c b/nuttx/libc/stdio/lib_libfwrite.c
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+/****************************************************************************
+ * libc/stdio/lib_libfwrite.c
+ *
+ * Copyright (C) 2007-2009, 2011 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> /* for CONFIG_STDIO_BUFFER_SIZE */
+
+#include <sys/types.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "lib_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_fwrite
+ ****************************************************************************/
+
+ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream)
+#if CONFIG_STDIO_BUFFER_SIZE > 0
+{
+ FAR const unsigned char *start = ptr;
+ FAR const unsigned char *src = ptr;
+ ssize_t ret = ERROR;
+ unsigned char *dest;
+
+ /* Make sure that writing to this stream is allowed */
+
+ if (!stream || (stream->fs_oflags & O_WROK) == 0)
+ {
+ set_errno(EBADF);
+ 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;
+ }
+
+ /* Loop until all of the bytes have been buffered */
+
+ while (count > 0)
+ {
+ /* Determine the number of bytes left in the buffer */
+
+ size_t gulp_size = stream->fs_bufend - stream->fs_bufpos;
+
+ /* Will the user data fit into the amount of buffer space
+ * that we have left?
+ */
+
+ 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 */
+
+ for (dest = stream->fs_bufpos; gulp_size > 0; gulp_size--)
+ {
+ *dest++ = *src++;
+ }
+ stream->fs_bufpos = dest;
+
+ /* Is the buffer full? */
+
+ if (dest >= 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;
+ }
+ }
+ }
+
+ /* Return the number of bytes written */
+
+ ret = src - start;
+
+errout_with_semaphore:
+ lib_give_semaphore(stream);
+
+errout:
+ return ret;
+}
+#else
+{
+ return write(stream->fs_filedes, ptr, count);
+}
+#endif /* CONFIG_STDIO_BUFFER_SIZE */
+