This utility was my impetus for getting this whole site reorganised into something vaguely navigable. I finally have some content almost worth posting :).
It's basically a tool that anyone with a Swiftlink cartridge, a null-modem cable, and a host equipped with a serial port, a C compiler and posix compliant termios libs should be able to use for uploading disk images. I wrote it to back up all my old disks, so getting transfers working in the opposite direction is a pretty low priority at the moment, as is cleaning up the code, given that it basically works. (Transfers a disk side in about five or six minutes).
It needs documenting, and should be made remotely userfriendly, and I need to fix a bug where sometimes it hangs between tracks if the host gets too busy at a bad time (eg if you're running a c64 emu in the foreground ;-)
Anyway, FWIW, the source to version zero is linked below. Untar the file, 'make' (you need Andre Fachat's xa to assemble the c64 & drive servers), type in 'otherend.bas' on your c64 (and save it to a scratch disk with a nice short filename; you'll need to reload it everytime the code falls over!!), run the c64 code, insert the disk you want an image of, then type 'snaffle diskname.d64' on the host. It only does tracks 1-35, no sector headers, and can't deal with copy-protected disks.
There are no precompiled binaries available at this time. Oh, nearly forgot; you need to edit main.c and change the parameter to srOpenPort to the path to the serial port you want it to use. This code has only been tested under Mac OS X versions 10.1.2 and 10.1.3, on a G4/AGP with a keyspan USB to Serial converter.