[cygwin] Borg 1.1.0 - ValueError: Location: parse failed

[theChaosCoder]

Seems like a cache and/or file:// path problem:

Steps:
borg init file:////synology/Backups/test/ -e none

borg info file:////synology/Backups/test/

Local Exception
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/borg/archiver.py", line 4024, in main
    exit_code = archiver.run(args)
  File "/usr/lib/python3.6/site-packages/borg/archiver.py", line 3952, in run
    return set_ec(func(args))
  File "/usr/lib/python3.6/site-packages/borg/archiver.py", line 141, in wrapper
    assert_secure(repository, kwargs['manifest'])
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 199, in assert_secure
    sm.assert_secure(manifest, manifest.key)
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 164, in assert_secure
    with cache_config:
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 231, in __enter__
    self.open()
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 255, in open
    self.load()
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 283, in load
    self.previous_location = recanonicalize_relative_location(previous_location, self.repository)
  File "/usr/lib/python3.6/site-packages/borg/cache.py", line 205, in recanonicalize_relative_location
    rl = Location(repo_location)
  File "/usr/lib/python3.6/site-packages/borg/helpers.py", line 1035, in __init__
    raise ValueError('Location: parse failed: %s' % self.orig)
ValueError: Location: parse failed: //synology/Backups/test

Platform: CYGWIN_NT-10.0 Chaos-PC 2.9.0(0.318/5/3) 2017-09-12 10:18 x86_64
Borg: 1.1.0  Python: CPython 3.6.1
PID: 12284  CWD: /home/anato
sys.argv: ['/usr/bin/borg', 'info', 'file:////synology/test/']
SSH_ORIGINAL_COMMAND: None

Then I remove the borg cache folder in home and the borg info command runs fine, but only once! The second time the same error is shown.

I happens only with file://...
/cygdrive/e/test is OK.

I also noticed that borg complains about a //synology as a archive-path , but NOT on --exclude-from or as a source folder wich I want to backup.

See also #2186

[ThomasWaldmann]

Just mount the stuff instead of using unc path //server/share?

[theChaosCoder]

That is what I'm doing right now.

But I think it is an error. Also the path validation is not consistent between archive path, source path and exclude-from path.

//Edit:
I mean does it make sense that this works?
borg create /cygdrive/z/test::test1 //synology/y/backmeup

And this not?
borg create //synology/x/test::test2 //synology/y/backmeup

And this only without cache
borg create file:////synology/x/test::test3 //synology/y/backmeup

Also you wrote in #2186 that to get such a path (//xyz) accepted is:
file:////servername/share/path

[ThomasWaldmann]

Hmm, did this work in 1.0.x, but stopped working in 1.1.0?

[theChaosCoder]

I think it stopped working with borg 1.0.10. I used 1.0.9 until now :)

[ThomasWaldmann]

https://tools.ietf.org/html/rfc8089 looks like it took until 2017 to even write this mess down as a RFC.

The problem described by OP can be reproduced by adding 'file:////server/share/path::archive' to test_canonical_path.

I must admit that I don't feel very motivated to fix this or try to implement what's described in the RFC.
Most times when the regex was touched, something else broke...

So, whoever is, feel invited to fix this, cover it with test cases and make a PR.

[seeker]

As a workaround you can either:

1. Create a network drive with net use B: \\\\server\\path-to-repo /persistent:no and then delete it when done net use B: /delete (works in a shell script run with cygwin)
   Make sure to not have any trailing slashes on the path, or you will get The network path was not found.
2. Create a symlink via cygwin ln -s '//server/path-to-repo' name-of-link and use that as the repo path

[ThomasWaldmann]

Just as a minor update to my comment "Most times when the regex was touched, something else broke...":

The regex got a bit simpler in master branch (in borg 2.0):

• repo::archive location (borg 1.x) was split into separate arguments for the repo and for the archive
• scp syntax was dropped, which also helps a bit against bad matches

So, whoever is, feel invited to fix this, cover it with test cases and make a PR.

Possibly add a relevant bounty for this 5 year old bug.

[ThomasWaldmann]

Checked this against current master (borg 2):

• The crash from the original report is gone. file:////server/share/path parses fine now and a full repo-create / create / repo-info / list round trip works, including the cache / security dir handling that blew up in 1.1. The regex simplification in borg 2 fixed that on its own.
• What is still not accepted is the bare //server/share/path form. Making it parse would be a small change: drop the // alternative from local_path_re, allow // in abs_path_re on Windows, and stop using Path.as_uri() for UNC paths (pathlib puts the server into the URL authority part - file://server/share/path - which borgstore's posixfs backend rejects, it only supports an empty host part).

But the parsing is the easy half, and it is not the half I am worried about.

The risky part is UNC semantics, and we can't verify those: fcntl/flock behaviour over SMB (that is what borgstore's posixfs locking relies on), atomic rename, fsync, and mtime granularity for the staleness / clock-skew checks. If any of that silently misbehaves on a network share, the failure mode is a repository that is corrupted or stuck locked - not a friendly parse error. CI can't cover a real UNC share either, so any tests we could add would only exercise the parser and would give a false sense of coverage for exactly the part that matters.

Also, on Linux and macOS a leading // is just /, so the feature would only ever mean something on Windows/cygwin - a very small target for that risk. Meanwhile there are workarounds that keep borg on a path whose semantics it can rely on (map a drive letter with net use, or a cygwin symlink, both mentioned above), and borg 2 has real network backends (sftp, s3, b2, rclone) for the "repository is not on local storage" case.

So: closing as not planned. If someone wants to pick it up anyway, the parser part is a few lines, but the burden of proof is on the locking / rename / fsync behaviour over SMB, not on the regex.