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https://github.com/JakeHillion/drgn.git
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vmtest.vm: support running with root directory different from the host
This will be useful for testing different architectures (e.g., by creating a rootfs with debootstrap) or different userspace environments. For example, we can test busybox with something like: mkdir busyboxroot busyboxroot/bin busyboxroot/tmp cp "$(which busybox)" busyboxroot/bin busyboxroot/bin/busybox --install busyboxroot/bin python3 -Bm vmtest.vm -k '*' -r busyboxroot Signed-off-by: Omar Sandoval <osandov@osandov.com>
This commit is contained in:
Omar Sandoval
parent
9e5fb3ef08
commit
6cc41dbcf8
2
setup.py
2
setup.py
@ -273,7 +273,7 @@ fi
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"""
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try:
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returncode = vmtest.vm.run_in_vm(
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command, Path(kernel_dir), Path(self.vmtest_dir)
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command, Path("/"), Path(kernel_dir), Path(self.vmtest_dir)
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)
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except vmtest.vm.LostVMError as e:
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self.announce(f"error on Linux {kernel_release}: {e}", log.ERROR)
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96
vmtest/vm.py
96
vmtest/vm.py
@ -12,8 +12,6 @@ import tempfile
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from util import nproc, out_of_date
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_9PFS_MSIZE = 1024 * 1024
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# Script run as init in the virtual machine.
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_INIT_TEMPLATE = r"""#!/bin/sh
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@ -37,39 +35,45 @@ HOSTNAME=vmtest
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VPORT_NAME=com.osandov.vmtest.0
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RELEASE=$(uname -r)
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# Set up overlayfs on the temporary directory containing this script.
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mnt=$(dirname "$0")
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mount -t tmpfs tmpfs "$mnt"
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mkdir "$mnt/upper" "$mnt/work" "$mnt/merged"
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# Set up overlayfs.
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if [ ! -w /tmp ]; then
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mount -t tmpfs tmpfs /tmp
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fi
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mkdir /tmp/upper /tmp/work /tmp/merged
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mkdir /tmp/upper/dev /tmp/upper/etc /tmp/upper/mnt
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mkdir -m 555 /tmp/upper/proc /tmp/upper/sys
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mkdir -m 1777 /tmp/upper/tmp
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if [ -e /tmp/host ]; then
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mkdir /tmp/host_upper /tmp/host_work /tmp/upper/host
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fi
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mkdir "$mnt/upper/dev" "$mnt/upper/etc" "$mnt/upper/mnt"
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mkdir -m 555 "$mnt/upper/proc" "$mnt/upper/sys"
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mkdir -m 1777 "$mnt/upper/tmp"
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mount -t overlay -o lowerdir=/,upperdir="$mnt/upper",workdir="$mnt/work" overlay "$mnt/merged"
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mount -t overlay -o lowerdir=/,upperdir=/tmp/upper,workdir=/tmp/work overlay /tmp/merged
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if [ -e /tmp/host ]; then
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mount -t overlay -o lowerdir=/tmp/host,upperdir=/tmp/host_upper,workdir=/tmp/host_work overlay /tmp/merged/host
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fi
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# Mount core filesystems.
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mount -t devtmpfs -o nosuid,noexec dev "$mnt/merged/dev"
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mkdir "$mnt/merged/dev/shm"
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mount -t tmpfs -o nosuid,nodev tmpfs "$mnt/merged/dev/shm"
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mount -t proc -o nosuid,nodev,noexec proc "$mnt/merged/proc"
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mount -t sysfs -o nosuid,nodev,noexec sys "$mnt/merged/sys"
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mount -t devtmpfs -o nosuid,noexec dev /tmp/merged/dev
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mkdir /tmp/merged/dev/shm
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mount -t tmpfs -o nosuid,nodev tmpfs /tmp/merged/dev/shm
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mount -t proc -o nosuid,nodev,noexec proc /tmp/merged/proc
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mount -t sysfs -o nosuid,nodev,noexec sys /tmp/merged/sys
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# cgroup2 was added in Linux v4.5.
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mount -t cgroup2 -o nosuid,nodev,noexec cgroup2 "$mnt/merged/sys/fs/cgroup" || true
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mount -t cgroup2 -o nosuid,nodev,noexec cgroup2 /tmp/merged/sys/fs/cgroup || true
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# Ideally we'd just be able to create an opaque directory for /tmp on the upper
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# layer. However, before Linux kernel commit 51f7e52dc943 ("ovl: share inode
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# for hard link") (in v4.8), overlayfs doesn't handle hard links correctly,
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# which breaks some tests.
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mount -t tmpfs -o nosuid,nodev tmpfs "$mnt/merged/tmp"
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mount -t tmpfs -o nosuid,nodev tmpfs /tmp/merged/tmp
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# Pivot into the new root.
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pivot_root "$mnt/merged" "$mnt/merged/mnt"
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pivot_root /tmp/merged /tmp/merged/mnt
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cd /
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umount -l /mnt
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# Load kernel modules.
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mkdir -p "/lib/modules/$RELEASE"
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mount -t 9p -o trans=virtio,cache=loose,ro,msize={_9PFS_MSIZE} modules "/lib/modules/$RELEASE"
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mount --bind {kernel_dir} "/lib/modules/$RELEASE"
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for module in configs rng_core virtio_rng; do
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modprobe "$module"
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done
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@ -172,7 +176,7 @@ class LostVMError(Exception):
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pass
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def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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def run_in_vm(command: str, root_dir: Path, kernel_dir: Path, build_dir: Path) -> int:
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match = re.search(
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r"QEMU emulator version ([0-9]+(?:\.[0-9]+)*)",
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subprocess.check_output(
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@ -183,8 +187,6 @@ def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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raise Exception("could not determine QEMU version")
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qemu_version = tuple(int(x) for x in match.group(1).split("."))
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# multidevs was added in QEMU 4.2.0.
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multidevs = ",multidevs=remap" if qemu_version >= (4, 2) else ""
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# QEMU's 9pfs O_NOATIME handling was fixed in 5.1.0. The fix was backported
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# to 5.0.1.
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env = os.environ.copy()
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@ -201,6 +203,12 @@ def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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)
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kvm_args = []
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virtfs_options = "security_model=none,readonly=on"
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# multidevs was added in QEMU 4.2.0.
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if qemu_version >= (4, 2):
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virtfs_options += ",multidevs=remap"
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_9pfs_mount_options = f"trans=virtio,cache=loose,msize={1024 * 1024}"
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with tempfile.TemporaryDirectory(prefix="drgn-vmtest-") as temp_dir, socket.socket(
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socket.AF_UNIX
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) as server_sock:
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@ -209,17 +217,31 @@ def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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server_sock.bind(str(socket_path))
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server_sock.listen()
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init = (temp_path / "init").resolve()
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with open(init, "w") as init_file:
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init_path = temp_path / "init"
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if root_dir == Path("/"):
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host_virtfs_args = []
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init = str(init_path.resolve())
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host_dir_prefix = ""
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else:
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host_virtfs_args = [
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"-virtfs",
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f"local,path=/,mount_tag=host,{virtfs_options}",
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]
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init = f'/bin/sh -- -c "/bin/mount -t tmpfs tmpfs /tmp && /bin/mkdir /tmp/host && /bin/mount -t 9p -o {_9pfs_mount_options},ro host /tmp/host && . /tmp/host{init_path.resolve()}"'
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host_dir_prefix = "/host"
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with init_path.open("w") as init_file:
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init_file.write(
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_INIT_TEMPLATE.format(
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_9PFS_MSIZE=_9PFS_MSIZE,
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cwd=shlex.quote(os.getcwd()),
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cwd=shlex.quote(host_dir_prefix + os.getcwd()),
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kernel_dir=shlex.quote(host_dir_prefix + str(kernel_dir.resolve())),
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command=shlex.quote(command),
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kdump_needs_nosmp="" if kvm_args else "export KDUMP_NEEDS_NOSMP=1",
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)
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)
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os.chmod(init, 0o755)
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init_path.chmod(0o755)
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with subprocess.Popen(
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[
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# fmt: off
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@ -234,10 +256,8 @@ def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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"-no-reboot",
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"-virtfs",
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f"local,id=root,path=/,mount_tag=/dev/root,security_model=none,readonly=on{multidevs}",
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"-virtfs",
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f"local,path={kernel_dir},mount_tag=modules,security_model=none,readonly=on",
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f"local,id=root,path={root_dir},mount_tag=/dev/root,{virtfs_options}",
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*host_virtfs_args,
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"-device", "virtio-rng-pci",
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@ -248,7 +268,7 @@ def run_in_vm(command: str, kernel_dir: Path, build_dir: Path) -> int:
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"-kernel", str(kernel_dir / "vmlinuz"),
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"-append",
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f"rootfstype=9p rootflags=trans=virtio,cache=loose,msize={_9PFS_MSIZE} ro console=0,115200 panic=-1 crashkernel=256M init={init}",
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f"rootfstype=9p rootflags={_9pfs_mount_options} ro console=0,115200 panic=-1 crashkernel=256M init={init}",
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# fmt: on
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],
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env=env,
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@ -312,6 +332,14 @@ if __name__ == "__main__":
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default=argparse.SUPPRESS,
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help="kernel to use (default: latest available kernel)",
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)
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parser.add_argument(
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"-r",
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"--root-directory",
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metavar="DIR",
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default=Path("/"),
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type=Path,
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help="directory to use as root directory in VM",
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)
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parser.add_argument(
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"command",
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type=str,
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@ -330,7 +358,7 @@ if __name__ == "__main__":
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try:
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command = " ".join(args.command) if args.command else "sh -i"
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sys.exit(run_in_vm(command, kernel_dir, args.directory))
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sys.exit(run_in_vm(command, args.root_directory, kernel_dir, args.directory))
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except LostVMError as e:
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print("error:", e, file=sys.stderr)
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sys.exit(args.lost_status)
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