On Sun, 06 Feb 2005 17:03:20 +0100, Michael Natterer <mitch@xxxxxxxx> wrote: > An alternative to implementing our own vfs would be to entirely > hide file handling from file plug-ins, for example by passing them > already opened GIOChannels which they would use to read/write. > It woud be easily possible to make the IO channels use some vfs > layer and the plug-ins wouldn't even notice. > > While this would make "straightforward" file plug-ins (which just > open, read sequentially, close) much easier to implement, it is > problematic for plug-ins which want to seek around in the files > a lot (like jpeg.c). GIOChannel has a seeking API, but we cannot > guarantee that for all vfs backends we may want to use. This seems like a sensible abstraction. There are two ways to handle the seeking problem: 1) Just make sure that all plug-ins that need to seek handle the can't seek error message correctly. This solution sucks. 2) Implement some mechanism whereby the plug-in signals ahead of time that it needs to be able to seek around. On non-seekable streams, the backend transparently uses temporary files (which of course can be seeked.) Rockwalrus
