Surface.init Bug Fix: Memory Corruption (Heap)

[Pyre909]

What do you want to change?

I want to fix a bug found while working on adding a Windows front end to Ghostty. The main bug causes a double free memory corruption in the environment variable map in Surface.init, which is freed twice when creating a terminal fails partly.

In Surface.zig there is a smaller bug found, which has a small fix. This fix cleans up the font grid, two derived configs, and two threads.

Files affected:
src/Surface.zig
src/termio/Exec.zig files

Fix:
Exec.init takes ownership even when it fails, and Surface's cleanup stops before it's handed off. Small change with a unit test.

Evidence:
Was able to reproduce this by forcing an allocation failure, which caused a segfault before and a clean error after. Confirmed on all macOS, Linux, and Windows.

Why do you want to make this change?

This was found while working on a fork to add Windows support. This bug affects core code which would run on every platform.

There is a PR mitchellh/libxev#251 for the async bug mentioned in #12050.

Additionally I would like to send fixes when permitted/accepted.

Open Disclosure:
Claude Code helped find the bug, wrote the fix and unit test. Claude Code ran the reproductions and code review. All of which helped in my review and understanding of the code that will be implemented.

I’m using Claude Code to accelerate my learning of Ghostty, Zig, and other projects I have an interest in and if possible contribute to fixes or adding features as it permits.

I acknowledge that:

• I have read the Contributing Guide and understand the contribution process.
• I have read and agree to follow the AI Usage Policy.
• I wrote this vouch request myself, in my own voice, without AI generating it.

[jcollie]

!vouch