### Purpose
This PR contains the set of changes needed to make Syncthing work on iOS
for [my iOS app for
Syncthing](https://github.com/pixelspark/sushitrain).
Most changes originate from [the Mobius Sync
fork](http://github.com/MobiusSync/syncthing/tree/ios). I have removed
the changes from their fork that are not strictly needed for my app
(i.e. their changes to the GUI and command line utilities, for instance)
and squashed it all in a single commit.
In summary, the changes are:
* Resolve non-absolute paths to the 'Documents' folder (basically the
only one an app can/should write user data to by default on iOS)
* Tweaking of build flags/conditions for iOS (i.e. determine which
basicfs_watch, ignoreresult variant to build for iOS)
* Disable upgrade mechanism on iOS
* Make `RequestGlobal` and `PullerProgress` public symbols
* Expose syncthing.app's Model instance (app.M)
* Add no-op stub for SetLowPriority on iOS
I would very much appreciate these changes to be (eventually) merged to
mainline syncthing, as this would allow my iOS app to track the mainline
source code directly and removes the need (for me at least) for
maintaining a separate fork. Perhaps the Mobius folks can also benefit
from this (although as noted this branch does not contain their changes
to e.g. the GUI).
### Testing
This branch has been tested with the iOS app and appears to work fine.
The full set of MobiusSync changes has been used before with success.
### Screenshots
n/a
### Documentation
There should be no visible changes for users due to this set of changes.
---------
Co-authored-by: Simon Pickup <simon@pickupinfinity.com>
This improves the ignore handling so that directories can be fully
ignored (skipped in the watcher) in more cases. Specifically, where the
previous rule was that any complex `!`-pattern would disable skipping
directories, the new rule is that only matches on patterns *after* such
a `!`-pattern disable skipping. That is, the following now does the
intuitive thing:
```
/foo
/bar
!whatever
*
```
- `/foo/**` and `/bar/**` are completely skipped, since there is no
chance anything underneath them could ever be not-ignored
- `!whatever` toggles the "can't skip directories any more" flag
- Anything that matches `*` can't skip directories, because it's
possible we can have `whatever` match something deeper.
To enable this, some refactoring was necessary:
- The "can skip dirs" flag is now a property of the match result, not of
the pattern set as a whole.
- That meant returning a boolean is not good enough, we need to actually
return the entire `Result` (or, like, two booleans but that seemed
uglier and more annoying to use)
- `ShouldIgnore(string) boolean` went away with
`Match(string).IsIgnored()` being the obvious replacement (API
simplification!)
- The watcher then needed to import the `ignore` package (for the
`Result` type), but `fs` imports the watcher and `ignore` imports `fs`.
That's a cycle, so I broke out `Result` into a package of its own so
that it can be safely imported everywhere in things like `type Matcher
interface { Match(string) result.Result }`. There's a fair amount of
stuttering in `result.Result` and maybe we should go with something like
`ignoreresult.R` or so, leaving this open for discussion.
Tests refactored to suit, I think this change is in fact quite well
covered by the existing ones...
Also some noise because a few of the changed files were quite old and
got the `gofumpt` treatment by my editor. Sorry not sorry.
---------
Co-authored-by: Simon Frei <freisim93@gmail.com>
