🐞 Issue: DOS Stub Should Exit Cleanly with Valid Header

[realJoshByrnes]

🐞 Issue: DOS Stub Should Exit Cleanly with Valid Header

Summary

The current DOS stub used in our PE builds is a minimal 64-byte file containing only the MZ header and null padding. While this satisfies the PE loader, it does not behave like a valid DOS executable when run in a DOS environment.

Problem

• The stub lacks any executable DOS code.
• Running the binary in DOS or DOSBox results in undefined behavior or silent failure.
• The header may be technically valid, but there's no instruction to exit DOS cleanly.

Expected Behavior

The DOS stub should:

• Contain a valid MZ header with a correct PE header offset at 0x3C.
• Include a minimal instruction (e.g. int 0x20 or retf) to exit DOS cleanly.
• Remain within the 64-byte constraint required by the PE loader.

Suggested Fix

Update the stub to include:

• A properly structured MZ header.
• A single DOS exit instruction at offset 0x40.
• Padding to ensure the total size is exactly 64 bytes.

Even if we can't fit a message like "This program cannot be run in DOS mode.", we should still ensure the stub behaves correctly when executed in a DOS-compatible environment.

Benefits

• Improves compatibility with DOS and DOSBox.
• Aligns with conventional PE stub behavior.
• Adds polish and correctness to low-level binary layout.