gvfs-fuse doesn't work (completely) with the sftp interface

[bj0]

When using the SFTP frontend via gvfs FUSE, there is a bug that causes some file operations to fail. Since this also happens with other SFTP implementations, and with very simple commands (see below), the bug is likely to be in gvfs FUSE -- although that doesn't necessarily mean that we can't work around it.

Some applications appear to work, like vi and gedit, but some do not, like OpenOffice.

You can see that this bug is present by creating a simple text file: file1, then:

> cat file1 > file2
> cat file2 >> file1
cat: write error: Operation not supported

file1 is zero-length after the second cat.

This bug is present when I use gvfs to connect to an openssh-server also.

[davidsarah]

The bug probably is not in our SFTP frontend, but any workaround would have to be implemented there (if possible).

[davidsarah]

We need to document this in source:docs/frontends/FTP-and-SFTP.txt . Accepting for 1.7 as a documentation bug.

[zooko]

This ticket should be cross-linked to a ticket on ​the Gnome Bugzilla. I also like to use ​http://launchpad.net to track issues that effect more than one project. You can create a ticket in launchpad which tracks both this ticket (Tahoe-LAFS #1049) and that ticket (Gnome #whatever-it-comes-out-to-be) and any other projects that are affected by this issue.

[davidsarah]

wiki:SftpFrontend#Gnomevirtualfilesystemgvfs documents that gvfs-FUSE is not supported, and why:

gvfs-FUSE, on the other hand, is not recommended for use with Tahoe. This is because it has to map POSIX filesystem requests onto GIO requests, and this mapping loses information -- some combinations of 'open' flags cannot be expressed in the GIO API, for example. Therefore it is impossible for gvfs-FUSE to provide a fully correct FUSE filesystem (or even one that is "good enough" for many applications).

Basically I think that gvfs-FUSE is misguided and cannot work. (sshfs doesn't have the problem described here, because it is mapping from the FUSE interface directly to SFTP, without GIO or any other intermediate layer.)

[zooko]

If you can explain more precisely what flags gvfs-fuse can't translate, which cause this to not-work, then I'll open a ticket on the Gnome and/or OpenOffice trackers for it.