On Mon, 4 Aug 2025 at 11:42, Florian Weimer via fuse-devel <fuse-devel@xxxxxxxxxxxxxxxxxxxxx> wrote: > > The FUSE protocol uses struct fuse_write_out to convey the return value > of copy_file_range, which is restricted to uint32_t. But the > copy_file_range interface supports a 64-bit copy operation. Given that > copy_file_range is expected to clone huge files, large copies are not > unexpected, so this appears to be a real limitation. That's a nasty oversight. Fixing with a new FUSE_COPY_FILE_RANGE_64 op, fallback to the legacy FUSE_COPY_FILE_RANGE. > There is another wrinkle: we'd need to check if the process runs in > 32-bit compat mode, and reject size_t arguments larger than INT_MAX in > this case (with EOVERFLOW presumably). But perhaps this should be > handled on the kernel side? Currently, this doesn't seem to happen, and > we can get copy_file_range results in the in-band error range. > Applications have no way to disambiguate this. That's not fuse specific, right? Thanks, Miklos
