This is an improvement of PR #4493 and related to (and maybe fixing) #4961
and #4475. Maybe fixing, because there is no clear reproducer for that
problem.
The previous PR added a mechanism to resurrect missing parent directories,
if there is a valid child file to be pulled. The same mechanism does not
exist for dirs and symlinks, even though a missing parent can happen for
those items as well. Therefore this PR extends the resurrection to all types
of pulled items.
In addition I moved the IsDeleted branch while iterating over
processDirectly to the existing IsDeleted branch in the WithNeed iteration.
This saves one pointless assignment and IsDeleted query. Also
We have the invalid bit to indicate that a file isn't good. That's enough for remote devices. For ourselves, it would be good to know sometimes why the file isn't good - because it's an unsupported type, because it matches an ignore pattern, or because we detected the data is bad and we need to rescan it.
Or, and this is the main future reason for the PR, because it's a change detected on a receive only device. We will want something like the invalid flag for those changes, but marking them as invalid today means the scanner will rehash them. Hence something more fine grained is required.
This introduces a LocalFlags fields to the FileInfo where we can stash things that we care about locally. For example,
FlagLocalUnsupported = 1 << 0 // The kind is unsupported, e.g. symlinks on Windows
FlagLocalIgnored = 1 << 1 // Matches local ignore patterns
FlagLocalMustRescan = 1 << 2 // Doesn't match content on disk, must be rechecked fully
The LocalFlags fields isn't sent over the wire; instead the Invalid attribute is calculated based on the flags at index sending time. It's on the FileInfo anyway because that's what we serialize to database etc.
The actual Invalid flag should after this just be considered when building the global state and figuring out availability for remote devices. It is not used for local file index entries.
To optimize WithNeed, which is called for the local device whenever an index
update is received. No tracking for remote devices to conserve db space, as
WithNeed is only queried for completion.
Unignored files are marked as conflicting while scanning, which is then resolved
in the subsequent pull. Automatically reconciles needed items on send-only
folders, if they do not actually differ except for internal metadata.
Prior to this, the following is possible:
- Create a symlink "foo -> /somewhere", it gets synced
- Delete "foo", it gets versioned
- Create "foo/bar", it gets synced
- Delete "foo/bar", it gets versioned in "/somewhere/bar"
With this change, versioners should never version symlinks.
After this change,
- Symlinks on Windows are always unsupported. Sorry.
- Symlinks are always enabled on other platforms. They are just a small
file like anything else. There is no need to special case them. If you
don't want to sync some symlinks, ignore them.
- The protocol doesn't differentiate between different "types" of
symlinks. If that distinction ever does become relevant the individual
devices can figure it out by looking at the destination when they
create the link.
It's backwards compatible in that all the old symlink types are still
understood to be symlinks, and the new SYMLINK type is equivalent to the
old SYMLINK_UNKNOWN which was always a valid way to do it.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3962
LGTM: AudriusButkevicius
Simon Frei
Jakob Borg
Audrius Butkevicius