fix: set umask 022 in AWF wrapper to prevent chroot hosts EACCES on rootless runners

[Copilot]

On rootless GitHub-hosted runners, AWF's writeConfigs fatally crashes with EACCES when writing the chroot /etc/hosts file, blocking all Smoke CI agent runs (100% failure rate, 31+ affected runs).

Root cause: mkdtempSync applies the process umask to its default mode 0700. A restrictive ambient umask (e.g. 0111, masking the execute bit) produces mode=600 on the staging directory — a directory without execute cannot be entered even by its owner. The fallback path compounds the issue by writing to a freshly-created /tmp/awf-chroot-<random> dir (wrong path, same permissions problem) instead of the already-created hostsRootDir.

Changes

• actions/setup/sh/install_awf_binary.sh — adds umask 022 to the generated AWF wrapper script before execing Node.js. Since exec preserves the calling process's umask, Node.js inherits it, ensuring mkdtempSync produces mode=700:

  #!/bin/bash
  # Ensure directories created by AWF (e.g. chroot hosts staging dir) have the
  # execute bit set. A restrictive ambient umask (e.g. masking bit 0100) turns
  # mkdtemp's default 0700 into 0600, making the directory non-traversable and
  # causing EACCES on rootless GitHub-hosted runners.
  umask 022
  exec "/path/to/node" "/path/to/awf-bundle.js" "$@"

  With the primary write now succeeding, the broken fallback is never reached.

• actions/setup/sh/install_awf_binary_test.sh — two regression tests:

  • Test 7: asserts install_awf_binary.sh contains umask 022 in the wrapper template
  • Test 8: asserts mkdtempSync under umask 022 produces mode=0700 (functional guard against the rootless EACCES scenario)

[github-actions]

Hey @app/copilot-swe-agent 👋 — thanks for the fix on the umask issue in the AWF wrapper script! A few things to address before this is ready:

• Remove WIP status — the [WIP] prefix in the title suggests this is not ready for review yet. Please update the title and confirm the changes are complete.
• Expand the PR description — the checklist-style body is minimal. Consider adding a brief explanation of the root cause, what the fix does, and any edge cases considered.

If you would like a hand finalizing this:

Update PR #46188: remove the [WIP] prefix from the title and expand the PR description to explain the root cause of the umask 022 issue in the AWF wrapper script, what the fix does, and any edge cases considered.

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[pelikhan]

@lpcox