Michael Crosby
107 lines
3.5 KiB
Bash
Executable File
107 lines
3.5 KiB
Bash
Executable File
#!/bin/bash
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# Copyright © 2026 Apple Inc. and the Containerization project authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# Builds the guest init filesystem (initfs.ext4) — and optionally a rootfs
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# tar.gz for OCI image creation — from the compiled vminitd/vmexec binaries.
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#
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# Runs INSIDE the Linux dev container (invoked by the root Makefile's `init`
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# target via linux_run on macOS, or directly on Linux). A real loop mount is
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# preferred; when loop devices aren't available (an unprivileged CI container,
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# or a dev VM without loop support) it falls back to `mke2fs -d`, which
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# populates the filesystem without mounting. Both paths yield an equivalent
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# ext4, so the build works whether or not the container is privileged.
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#
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# The rootfs layout below MUST stay in sync with cctl's InitImage rootfs
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# (Sources/cctl/RootfsCommand.swift): directories bin/ sbin/ dev/ sys/
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# proc/self/ run/ tmp/ mnt/ var/, sbin/vminitd + sbin/vmexec at mode 0755, and
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# a proc/self/exe -> sbin/vminitd symlink ("hack for swift init's booting").
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set -euo pipefail
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usage() {
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echo "usage: $0 --vminitd PATH --vmexec PATH --ext4 OUT.ext4 [--tar OUT.tar.gz] [--size 512M]" >&2
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exit 2
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}
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VMINITD=
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VMEXEC=
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EXT4=
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TAR=
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SIZE=512M
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while [ $# -gt 0 ]; do
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case "$1" in
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--vminitd) VMINITD=$2; shift 2 ;;
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--vmexec) VMEXEC=$2; shift 2 ;;
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--ext4) EXT4=$2; shift 2 ;;
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--tar) TAR=$2; shift 2 ;;
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--size) SIZE=$2; shift 2 ;;
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*) usage ;;
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esac
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done
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[ -n "$VMINITD" ] && [ -n "$VMEXEC" ] && [ -n "$EXT4" ] || usage
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[ -f "$VMINITD" ] || { echo "ERROR: vminitd not found: $VMINITD" >&2; exit 1; }
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[ -f "$VMEXEC" ] || { echo "ERROR: vmexec not found: $VMEXEC" >&2; exit 1; }
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umask 022
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STAGING=$(mktemp -d)
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MNT=
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cleanup() {
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if [ -n "$MNT" ]; then
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mountpoint -q "$MNT" 2>/dev/null && umount "$MNT" 2>/dev/null || true
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rmdir "$MNT" 2>/dev/null || true
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fi
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rm -rf "$STAGING"
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}
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trap cleanup EXIT
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# Directory structure — keep in sync with RootfsCommand.directories.
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for d in bin sbin dev sys proc/self run tmp mnt var; do
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mkdir -p "$STAGING/$d"
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done
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install -m 0755 "$VMINITD" "$STAGING/sbin/vminitd"
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install -m 0755 "$VMEXEC" "$STAGING/sbin/vmexec"
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ln -sf sbin/vminitd "$STAGING/proc/self/exe"
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mkdir -p "$(dirname "$EXT4")"
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rm -f "$EXT4"
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truncate -s "$SIZE" "$EXT4"
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# Prefer a real loop mount; fall back to `mke2fs -d` when it isn't available.
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if mkfs.ext4 -F -q "$EXT4" \
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&& MNT=$(mktemp -d) \
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&& mount -o loop "$EXT4" "$MNT" 2>/dev/null; then
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echo "==> populating $EXT4 via loop mount"
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cp -a "$STAGING"/. "$MNT"/
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sync
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umount "$MNT"
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rmdir "$MNT"
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MNT=
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else
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echo "==> loop mount unavailable; populating $EXT4 via mke2fs -d"
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if [ -n "$MNT" ]; then rmdir "$MNT" 2>/dev/null || true; MNT=; fi
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rm -f "$EXT4"
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truncate -s "$SIZE" "$EXT4"
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mkfs.ext4 -F -q -d "$STAGING" "$EXT4"
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fi
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echo "==> wrote initfs $EXT4"
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if [ -n "$TAR" ]; then
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mkdir -p "$(dirname "$TAR")"
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rm -f "$TAR"
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tar -czf "$TAR" -C "$STAGING" .
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echo "==> wrote rootfs tar $TAR"
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fi
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