112 lines
2.4 KiB
Bash
112 lines
2.4 KiB
Bash
#!/bin/bash
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# PicoShim Builder
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# 2024
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if [ $EUID -ne 0 ]; then
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echo "You MUST run this program with sudo or as root."
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exit 1
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fi
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if [ "$1" == "" ]; then
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echo "No shim passed, please pass a shim to the args."
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echo "$@"
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exit 1
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fi
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SCRIPT_DIR=$(dirname "$0")
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VERSION=1
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ARCHITECTURE="$(uname -m)"
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case "$ARCHITECTURE" in
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*x86_64* | *x86-64*) ARCHITECTURE=x86_64 ;;
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*aarch64* | *armv8*) ARCHITECTURE=aarch64 ;;
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*i[3-6]86*) ARCHITECTURE=i386 ;;
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*) fail "Unsupported architecture $ARCHITECTURE" ;;
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esac
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source ${SCRIPT_DIR}/lib/extract_initramfs.sh
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source ${SCRIPT_DIR}/lib/detect_arch.sh
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source ${SCRIPT_DIR}/lib/rootfs_utils.sh
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echo "PicoShim builder"
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echo "requires: binwalk, fdisk, cgpt, mkfs.ext2, numfmt"
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SHIM="$1"
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initramfs="/tmp/initramfs_path"
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rootfs_mnt="/tmp/picoshim_rootmnt"
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loopdev=$(losetup -f)
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CGPT="${SCRIPT_DIR}/lib/bin/$ARCHITECTURE/cgpt"
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SFDISK="${SCRIPT_DIR}/lib/bin/$ARCHITECTURE/sfdisk"
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# gets the initramfs size, e.g: 6.5M, and rounds it to the nearest whole number, e.g: 7M
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# we're giving it 5 extra MBs to allow the busybox binaries to be installed
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initramfs_size=$(($(du -sb "$initramfs" | awk '{print $1}' | numfmt --to=iec | awk '{print int($1) + ($1 > int($1))}') + 2))
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kernsize=$(fdisk -l ${loopdev}p2 | head -n 1 | awk '{printf $3}')
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# size of stateful partition in MiB
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state_size="1"
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rm -rf $initramfs # cleanup previous instances of picoshim, if they existed.
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mkdir -p $initramfs
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rm -rf $rootfs_mnt # cleanup previous instances of picoshim, if they existed.
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mkdir -p $rootfs_mnt
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if [ -f "$SHIM" ]; then
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shrink_partitions "$SHIM"
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losetup -P "$loopdev" "$SHIM"
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else
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exit 1
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fi
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arch=$(detect_arch $loopdev)
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extract_initramfs_full "$loopdev" "$initramfs" "/tmp/shim_kernel/kernel.img" "$arch"
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dd if="${loopdev}p2" of=/tmp/kernel-new.bin bs=1M oflag=direct status=none
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fdisk "$loopdev" <<EOF > /dev/null 2>&1
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d
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3
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p
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d
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2
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p
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n
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3
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+${initramfs_size}M
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n
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2
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+${kernsize}M
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p
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w
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EOF
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dd if=/tmp/kernel-new.bin of="${loopdev}p2" bs=1M oflag=direct status=none
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echo "creating new filesystem on rootfs"
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echo "y" | mkfs.ext2 "$loopdev"p3 -L ROOT-A > /dev/null 2>&1
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echo "mounting & moving files from initramfs to rootfs"
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mount "$loopdev"p3 "$rootfs_mnt"
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mv "$initramfs"/* "$rootfs_mnt"/
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create_stateful "$loopdev"
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echo "adding kernel priorities"
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"$CGPT" add "$loopdev" -i 2 -t kernel -P 1
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"$CGPT" add "$loopdev" -i 3 -t rootfs
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echo "cleaning up"
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losetup -D
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truncate_image "$SHIM"
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rm -rf $initramfs
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rm -rf $rootfs_mnt
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umount "$loopdev"p3
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