Formatting with a symlinked folder may randomly corrupt files

[sean-mcmanus]

Our latest Insiders release has a new multi-root implementation (which fixes this bug): https://github.com/microsoft/vscode-cpptools/releases/tag/0.27.0-insiders. Please let us know if you find any multi-root-related bugs or regressions so we can prioritize fixing those for 0.27.0.

I am affected by the bug. My working directory is a symlink, and once in a while when I reformat the code my file becomes corrupted. I am using /0.27.0-insiders2

Originally posted by @olzhas in #1073 (comment)

[sean-mcmanus]

@olzhas Can you provide more info? What OS are you on? Does it repro with a single root workspace folder or does it require multiple root folders? Do you know of a way to make the "once in a while" more consistent?

The root cause might be related to other known symlink issues, such as #4573 or #3123 .

[mmoskal]

When I have the same file open through two different symlinks (cpp tools go to definition finds it differently than when I open it from the file explorer on the side), and I try to format one of the files, it gets corrupted. Closing one of the copies fixes the problem

I'm on macOS 10.14.6, VSCode 1.44.2.

[KnBrckr]

I've noticed I'm seeing this issue. On Windows 10, VSCode 1.44.2, cpptools 0.27.1, using WSL and a symlinked directory. I haven't sorted out how to recreate the problem reliably. I see it on some tabs, not others. On the tab I was seeing this reliably, closed the file and reopened in a new tab, no longer seeing the corruption. The file was only open in a single tab.

[rfjakob]

A few more reports of data corruption that have been auto-closed: #2941 #3796 #3809 #1073

I just lost about an hour's work because of this. How is this not a P1 issue? Shouldn't formatting be disabled per default until this is sorted out?

[sean-mcmanus]

@rfjakob The bug hasn't gotten many upvotes and only seems to happen when symlinked folders are used. I'm not sure if we have a repro yet too.

[rfjakob]

Counting through the duplicates, there's independent reports from

• @pbnjay @SE2Dev @aytekinar @WillEwing @bojunehsu @winterscar @samdenty @mmichon @darkfader @nebbles @maciejmatczak @Victsz @alanbirtles @olzhas @jkhoogland
  • ( from clang-format corrupting files? #1073 )
• @ghost
  • ( from Formatting code on save pastes garbage from clipboard. #2941 )
• @Shachlan
  • ( from Format on save creates gibberish #3796 )
• @TheGreatRambler
  • ( from Weird text appears when format on save is used #3809 )

I guess compared to the total user base of VS Code, that's few, but the impact is quite high (data loss).

If this were my project, I would disable code formatting per default until a reproducer is found.

[rfjakob]

Ok, I found a reproducer:

(1) Prepare source code repo & symlink

mkdir /tmp/issue5061
cd /tmp/issue5061
git clone --branch v1.6.2 https://github.com/rfjakob/earlyoom.git
ln -s earlyoom earlyoom-symlink

(2) In VS Code: File -> New Window. Add Folder: /tmp/issue5061/earlyoom-symlink

(3) In the sidebar, open meminfo.c and main.c

(4) In main.c go to line 405 and Go To Definition of parse_meminfo()

(5) You now have meminfo.c open two times. Once via /tmp/issue5061/earlyoom-symlink/meminfo.c and 2nd time via /tmp/issue5061/earlyoom/meminfo.c . That's the first bug.

(6) Write "foo" to the bottom of the 2nd meminfo.c, save.

(7) Jump back to 1st meminfo.c, scroll to bottom. Don't change anything. Save. Garbage gets appended. That's the 2nd bug.

(8) Click save again for more garbage (each save appends more)

[rfjakob]

Screenshots for steps 1-8 below: