It looks like your problem is different from 'no way to set output_tiff=1 via C-API':
- LibRaw internals are different from dcraw's while we keep some compatibility via dcraw_emu sample
- in particular, there is no document_mode (-d/-D options in dcraw), because unaltered raw data is already accessible via https://www.libraw.org/docs/API-datastruct.html#libraw_rawdata_t
So, it looks like you need to implement direct access to this data from your app (I'm not sure you need intermediate TIFF storage because data is already here).
It looks like your problem is different from 'no way to set output_tiff=1 via C-API':
- LibRaw internals are different from dcraw's while we keep some compatibility via dcraw_emu sample
- in particular, there is no document_mode (-d/-D options in dcraw), because unaltered raw data is already accessible via https://www.libraw.org/docs/API-datastruct.html#libraw_rawdata_t
So, it looks like you need to implement direct access to this data from your app (I'm not sure you need intermediate TIFF storage because data is already here).