replace dd with mv_data to reduce memory usage

Containerfile

@@ -1,3 +1,8 @@
+FROM debian:bookworm AS mv_data
+RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends build-essential ca-certificates git
+RUN git clone --depth=1 https://github.com/nkraetzschmar/mv_data
+RUN make -C mv_data install
+
 FROM debian:bookworm AS aws-kms-pkcs11
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends build-essential awscli ca-certificates cmake git libcurl4-openssl-dev libengine-pkcs11-openssl libjson-c-dev libssl-dev libp11-kit-dev libp11-dev zlib1g-dev
 RUN git clone --depth=1 --recurse-submodules -b 1.11.25 https://github.com/aws/aws-sdk-cpp
@@ -9,6 +14,7 @@ RUN cp "/usr/lib/$(uname -m)-linux-gnu/pkcs11/aws_kms_pkcs11.so" /aws_kms_pkcs11
 FROM debian:bookworm
 COPY pkg.list /pkg.list
 RUN apt update && DEBIAN_FRONTEND=noninteractive apt install -y --no-install-recommends $(cat /pkg.list) && rm /pkg.list
+COPY --from=mv_data /usr/bin/mv_data /usr/bin/mv_data
 COPY --from=aws-kms-pkcs11 /aws_kms_pkcs11.so /aws_kms_pkcs11.so
 RUN mv /aws_kms_pkcs11.so "/usr/lib/$(uname -m)-linux-gnu/pkcs11/aws_kms_pkcs11.so"
 COPY builder /builder

builder/image.d/makedisk

@@ -59,6 +59,9 @@ while IFS=$'\t' read -r part_uuid type size syslinux file label; do
 	gpt_entry=$(grep -iF "uuid=$part_uuid" <<< "$gpt_dump")
 	start_sector=$(grep -oP '(?<=start=) *[0-9]+' <<< "$gpt_entry" | tr -d '[:blank:]')
 	num_sectors=$(grep -oP '(?<=size=) *[0-9]+' <<< "$gpt_entry" | tr -d '[:blank:]')
-	dd if="$file" of="$img" bs="$sector_size" seek="$start_sector" count="$num_sectors" conv=notrunc
+
+	offset=$(( sector_size * start_sector ))
+	len=$(( sector_size * num_sectors ))
+	mv_data --input "$file" --output "$img" --output-offset "$offset" --length "$len"
 	rm "$file"
 done <<< "$second_pass"

setup_namespace

@@ -4,7 +4,7 @@ set -eufo pipefail
 
 if [ "${1-}" = --second-stage ]; then
 	shift
-	mount -t tmpfs -o size=8G tmpfs /tmp
+	mount -t tmpfs -o size=4G tmpfs /tmp
 	"$@"
 else
 	unshare --map-root-user --map-users auto --map-groups auto --mount "$0" --second-stage "$@"