fix(linux/kwin): retry init with fully dropped elevated privileges in case KWin is missing CAP_SYS_NICE on linux

[Kishi85]

Description

Archlinux/CachyOS packaged kwin-6.6.5-3 is not assigning CAP_SYS_NICE to KWin therefore breaking kwingrab which was allowed to retain the capability to improve streaming performance as part of #5075. Although this is likely a bug on the packaging end it should be properly handled in Sunshine.

This PR adds handling for KWin missing CAP_SYS_NICE by checking if init succeeded in binding the screencast extension. Should that not be the case it's logging a warning, dropping ALL elevated capabilities and doing a full reinit of the screencast instance on the display object before continuing with starting the stream.

Screenshot

Issues Fixed or Closed

Roadmap Issues

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

Codecov Report

❌ Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@1a6fb5f). Learn more about missing BASE report.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/platform/linux/kwingrab.cpp	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5212   +/-   ##
=========================================
  Coverage          ?   17.82%           
=========================================
  Files             ?      111           
  Lines             ?    24173           
  Branches          ?    10695           
=========================================
  Hits              ?     4310           
  Misses            ?    15489           
  Partials          ?     4374           

Flag	Coverage Δ
Archlinux	11.22% <0.00%> (?)
FreeBSD-amd64	13.35% <ø> (?)
Homebrew-ubuntu-22.04	13.57% <0.00%> (?)
Linux-AppImage	12.15% <0.00%> (?)
Windows-AMD64	14.85% <ø> (?)
Windows-ARM64	13.19% <ø> (?)
macOS-arm64	18.86% <ø> (?)
macOS-x86_64	18.34% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/platform/linux/kwingrab.cpp	0.00% <0.00%> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud