Questions about getting the host path

[g-willems]

Hi,

Since #1372 we can read a xattr to get the host path of a file opened via the document portal.
After testing, there are a few things I would like to clarify:

• the xattr value always has a final \x00 char, seems to be some kind of null-separated list. What's the reason behind having a list? When can I expect multiple elements, and how to evaluate the result in that case?
• When I open a folder with the portal then a file from within that folder, the returned file host path is the one of the parent folder. Is it a bug or a feature?

[swick]

The user.document-portal.host-path xattr is a NULL-terminated string with the same value as returned in GetHostPaths. The fact that it is NULL-terminated could be documented better. If you see a discrepancy between GetHostPaths and the xattr, please file a bug report.

[g-willems]

It was intended to be give the same results as calling GetHostPaths on the portal, so the same code to resolve the result of the portal would be needed to resolve the xattr. Is that a problem?

Not a problem at all, it's of course expected that both GetHostPaths and the xattr are in sync, which is the case for the folder /run/user/1000/doc/12345/b in my example above.

But for the file /run/user/1000/doc/12345/b/c/d.txt, there is no GetHostPaths possible because the file was not opened via the portal, but directly as descendant of the folder. So if we really want to keep GetHostPaths and the xattr in sync, the xattr should probably not be available either for that file.

Another possibility would be to consider that as there is no GetHostPaths for /run/user/1000/doc/12345/b/c/d.txt then there is no need to keep the xattr in sync with something that is not available, so we can set the xattr to whatever value we want, preferably /a/b/c/d.txt\x00 instead of /a/b\x00.

I'm personally reluctant to add new APIs, I can just cache all the folders host paths in my app to resolve the files host paths without using the xattr.
But as said the current behavior for the file doesn't make sense to me, so I would personally propose to either not provide a xattr for the file, or change it to return its real host path instead of the parent folder one.

[swick]

Another possibility would be to consider that as there is no GetHostPaths for /run/user/1000/doc/12345/b/c/d.txt then there is no need to keep the xattr in sync with something that is not available, so we can set the xattr to whatever value we want, preferably /a/b/c/d.txt\x00 instead of /a/b\x00.

Good point. I would be willing to review a PR adding this functionality.

[swick]

FWIW, there is now a PR which adds python based document portal tests (#1594) which could use a test for the xattr.

[swick]

Did the changes in #1597

[g-willems]

Thank you!
I'll give it a try.

[g-willems]

Tested #1597 , works fine, thank you very much!