libssh2_channel_window_write_ex - Check the status of the write window
unsigned long libssh2_channel_window_write_ex(LIBSSH2_CHANNEL *channel,
unsigned long *window_size_initial)
Check the status of the write window Returns the number of bytes which
may be safely writen on the channel without blocking.
’window_size_initial’ (if passed) will be populated with the size of
the initial window as defined by the channel_open request
Number of bytes which may be safely writen on the channel without