Detect database file changes using hash

[droidmonkey]

Type of change

• ✅ Refactor (significant modification to existing code)
• ✅ New feature (non-breaking change which adds functionality)

Description and Context

Cleanup Database Save Functions

• Make a clear distinction between saving to the existing file path and saving to a new file path
• Use proper save function calls in CLI

Move FileWatcher into database class

• Fix Could not open the database file while attempting to autoreload #3506
• Fix Detect changes to database file prior to save and prompt to merge #2389
• Fix External Changes on Samba Share not recognized on Linux #2536
• Fix "closing without saving" prompt when database was not modified and was on external storage unmounted without closing keepass #2230

Every database that has been opened now watch's it's own file. This allows the database class to manage file changes and detect fail conditions during saving. Additionally, all stakeholders of the database can listen for the database file changed notification and respond accordingly.

Performed significant cleanup of the autoreload code within DatabaseWidget. Fixed several issues with handling changes due to merging, not merging, and other scenarios while reloading.

Prevent database saves to the same file if there are changes on disk that have not been merged with the open database.

Improve database and CLI tests

Testing strategy

Tested manually and improved test cases.

Checklist:

• ✅ I have read the CONTRIBUTING document. [REQUIRED]
• ✅ My code follows the code style of this project. [REQUIRED]
• ✅ All new and existing tests passed. [REQUIRED]
• ✅ I have compiled and verified my code with -DWITH_ASAN=ON. [REQUIRED]
• ✅ My change requires a change to the documentation, and I have updated it accordingly.
• ✅ I have added tests to cover my changes.

[louib]

some comments, mainly reviewed the CLI changes

[droidmonkey]

Changes made and fixed tests

[droidmonkey]

@phoerious this is ready for your review

[droidmonkey]

Changes made, I recommend a merge commit for this one since a lot of fundamental code was changed.

[phoerious]

If all three commits compile separately, you can simply to a rebase merge. Otherwise squash them.

[droidmonkey]

I will verify but pretty sure they do.

[FlorentDotMe]

That's a great improvement ! Thank you for your work. As the new release isn't published yet, I don't really want to open a new issue. Just to point out an unexpected behavior with this feature.

Expected Behavior

User A and User B are simultaneously using the same keepass file.

User A is editing the new entry E1. At the same time, User B is editing a new entry E2. User A is the first to validate his entry E1 while User B is still editing E2. Database is updated. Then User B validates his entry E2. Database is updated. Both users see E1 and E2 in the database.

Current Behavior

User A is editing the new entry E1. At the same time, User B is adding a new entry E2. User A is the first to validate his entry E1 while User B is still editing E2. Database is updated. Then User B validates his entry E2. Database is NOT updated. Finally, only E1 was added to the database and E2 is lost.

Debug Info

KeePassXC - Version 2.5.0-snapshot
Build Type: Snapshot
Revision: 4cc06f9

Qt 5.11.3
Debugging mode is disabled.

Operating system: Debian GNU/Linux 10 (buster)
CPU architecture: x86_64
Kernel: linux 4.19.0-5-amd64

Enabled extensions:

• Auto-Type

Cryptographic libraries:
libgcrypt 1.8.4

[droidmonkey]

This scenario would occur without this change. Please open a new issue for this and a more refined sequence of events please.