int fseek(FAR FILE *stream, long int offset, int whence)
{
#if CONFIG_STDIO_BUFFER_SIZE > 0
/* Flush any valid read/write data in the buffer (also verifies stream) */
if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0)
{
return ERROR;
}
#else
/* Verify that we were provided with a stream */
if (!stream)
{
set_errno(EBADF);
return ERROR;
}
#endif
/* On success or failure, discard any characters saved by ungetc() */
#if CONFIG_NUNGET_CHARS > 0
stream->fs_nungotten = 0;
#endif
/* Perform the fseek on the underlying file descriptor */
return lseek(stream->fs_fd, offset, whence) == (off_t)-1 ? ERROR : OK;
}
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 == NULL)
{
set_errno(EBADF);
return ret;
}
if ((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:
if (ret < 0)
{
stream->fs_flags |= __FS_FLAG_ERROR;
}
return ret;
}