Fix dedicated runtime error

[winterheart]

Pull Request Type

• [ ] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [ ] Build and Dependency changes
• [x] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [x] Network changes
  • [ ] Other changes

Description

netgame_info is limited by PAGENAME_LEN (35) and this cause SIG_ABORT if user pass very long filename to -dedicated config option, as discovered in #571. Additional check for filename existence. Minor enhancements to related code.

Related Issues

Fixes #571

Screenshots (if applicable)

Checklist

• [x] I have tested my changes locally and verified that they work as intended.
• [x] I have documented any new or modified functionality.
• [x] I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• [x] I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

Additional Comments

[jengelh]

There's a more comprehensive resolution in #579 for part of the issues. SIGABRT is not guaranteed, in my case it just wrote past the buffer silently, because, AIUI, not even ASAN adds guard zones inside structs so they stay layout-compatible to non-ASAN-enabled code.

[winterheart]

Superseded by #579