I´m porting the clib version of fasm to my Os ,and i have one problem:
If the output file already exists and is bigger than the new version, the new file should be truncated, but i don´t know if the file must be truncated when the file is closed or if the filesize must be set to 0 after
the open call.
Also the output file is opened in mode 'w ' wich from a old 'C' manual
i have this means open a txt file for write , why not use mode 'wb ' instead.

The "create" call should truncate the file on opening it. The "open" is used only for reading files.