Sharing files via /tmp

[oSoMoN]

I am creating a new topic to continue a discussion that was started in another thread.

Excerpts:

Call for testing: MuseScore v2.1.0

Firefox puts the score in /tmp if you say you want to open the file in MuseScore immediately.

Call for testing: MuseScore v2.1.0

As for the general situation of sharing files via /tmp-- this is not supported at this time for the reasons I mentioned before because /tmp is something different to the snap and to the system’s firefox. It is technically possible to make using the per-snap /tmp optional, but I’m not sure this fits into the project’s plans. At a minimum, it would be confusing that some apps could see the system /tmp and others could not. An architect would have to weigh in on this.

I’m seeing the same problem when opening e-mail attachments from thunderbird with the libreoffice snap. Thunderbird saves a temporary copy of the attachment to the system-wide /tmp, and libreoffice fails to see it:

/tmp/mozilla_osomon0/test.odt doesn't exist

Should firefox and thunderbird be “fixed” to write files to some other place under $HOME instead of /tmp ?

Or as suggested by @jdstrand, would it be somehow possible to have the libreoffice snap (and others interested in that use case) see the system-wide /tmp ?

[niemeyer]

We probably don’t want that sort of off-the-hook communication between snaps as it becomes pretty much impossible to mediate. Who else will be opening that file besides libreoffice and mozilla?

The proper way to do that is to ask the application registered to open files of that type to have a look at that file, and only after the user has approved that interaction.

There’s some relevant discussion about this at the bottom of the xdg-open improvements topic.

Meanwhile, sharing via somewhere in $HOME may be the best way to go indeed.

[oSoMoN]

The proper way to do that is to ask the application registered to open files of that type to have a look at that file, and only after the user has approved that interaction.

That makes sense, but assuming the caller placed the file in the system-wide /tmp (or in its own confined /tmp), the receiving application still won’t be able to see it. Would the xdg-open wrapper grow some mechanism to make the file visible to the receiver?

[Ads20000]

I don’t really follow what Niemeyer is saying here, but this is an issue that needs fixing somehow, I just tried to open a Word document from a Facebook group using the LibreOffice snap (I’ve removed the Deb and just have that installed) and because I said ‘Open’ rather than ‘Save’, it error-ed out (attached below) and didn’t open the file. If we made the LibreOffice snap default one day and someone who isn’t technical ran into this bug, they would be very confused and annoyed indeed.

What steps are we going to take to resolve this issue? Do we somehow allow access to /tmp for opening files or do we have to apply a custom patchset to all applications that try saving to /tmp or what?

As you can see, it’s even worse if someone ticks the ‘Do this automatically for files like this from now on’ button because then they really can’t see how to fix issue unless they work out what the problem is and Google the right stuff online to find the way to change the setting back. Very unlikely that a non-technical person would be able to do this.

_{Would’ve smudged those screenshots but I don’t have fast enough Internet to get GIMP really xD. The difference in file names is because I tried to open this multiple times but got the same error}

[niemeyer]

We need to think about it some more. In general our policy is to not require applications to be changed for them to be used as a snap, so we’ll try to preserve that in this case as well. At the same time, this is a pretty unfortunate behavior from Firefox for several reasons, some of which may be better understood in this super long thread coming through many years: https://bugzilla.mozilla.org/show_bug.cgi?id=69938

Quick workarounds:

• Save the file in $HOME/Downloads or similar, instead of trying to open it directly from /tmp
• Change the location in the TMP environment variable with which Firefox runs

[Ads20000]

It’s a great policy!

Oh, Firefox uses an environment variable for that? Would be easiest if we snapped Firefox and got a scriptlet to do that, that wouldn’t involve changing Firefox itself at all (though it wouldn’t fix the bug for nearly all Firefox users)!