feat: Add ARGS_FILE to pass QEMU arguments exactly

[anvilsong]

Defect

src/entry.sh (lines 59, 63, 66 on master 1e99833) launches QEMU with:

exec "${cmd[@]}" ${ARGS:+ $ARGS} >"$pipe" 2>&1

Because $ARGS is unquoted it is word-split on whitespace, and quotes inside it are not removed, so a QEMU argument containing a space cannot be passed (e.g. -device foo,bar="a b"). Minimal repro (same expansion, printing argv):

cmd=(printf 'argv: [%s]\n')
ARGS='-device foo,bar="a b" -name "my vm"'
"${cmd[@]}" ${ARGS:+ $ARGS}

Output:

argv: [-device]
argv: [foo,bar="a]
argv: [b"]
argv: [-name]
argv: ["my]
argv: [vm"]

Fix

Add an optional ARGS_FILE variable: a file with one QEMU argument per line, appended verbatim to the cmd array (empty lines skipped). ARGS/ARGUMENTS behave as before, so nothing existing changes. Documented in docs/environment.md.

Testing

• shellcheck (0.11.0, with the flags from .github/workflows/check.yml) is clean on src/entry.sh.
• Ran the new block standalone with a file containing -device, foo,bar="a b", an empty line, -name, my vm: argv is -device, foo,bar="a b", -name, my vm.
• Not tested: full Docker build / real QEMU boot.

🤖 Generated with Claude Code

[kroese]

Yes, this is a known issue. But luckily it never caused much problems for users since it is pretty rare to have QEMU parameters to have spaces for most usecases.

In any case it needs to be fixed in qemus/qemu (the base image) and not in dockur/windows. And also Im not so keen on just adding a second ARGUMENTS variable to just to workaround it. If it is fixed properly in the base image (by generating the argument list based on an array instead of a string), then the normal ARGUMENTS could just support spaces. The reason why I did not implement it yet, is because it requires changes in a lot of places and since the problem affects so little users I was not sure if it was worth the effort.