Function ktxTexture1_CreateFromStdioStream 

pub unsafe extern "C" fn ktxTexture1_CreateFromStdioStream(
    stdioStream: *mut FILE,
    createFlags: ktxTextureCreateFlags,
    newTex: *mut *mut ktxTexture1,
) -> ktx_error_code_e

These four create a ktxTexture1 provided the data is in KTX format.