Download and patch Pop!_OS ISO images to enable persistent storage

pop-os-persistent.sh

#!/bin/bash
# Download and patch Pop!_OS ISO images to enable persistent storage

set -e

IMAGES=(

	"Pop!_OS 20.04 LTS"
	"https://iso.pop-os.org/20.04/amd64/intel/10/pop-os_20.04_amd64_intel_10.iso"
	"username=pop-os noprompt  ---"
	"username=pop-os persistent   "
	"ead5d784d04aecc8eec846e507c526a0d2983335c8fe3d1fb1498edb6654287d"

	"Pop!_OS 20.04 LTS (NVIDIA)"
	"https://iso.pop-os.org/20.04/amd64/nvidia/10/pop-os_20.04_amd64_nvidia_10.iso"
	"username=pop-os noprompt  modules_load=nvidia ---"
	"username=pop-os modules_load=nvidia persistent   "
	"0b43adcc75b1dff3707273575157a77485be6813b0bddd2212ee4ce1d57e933c"

	"Pop!_OS 22.04 LTS"
	"https://iso.pop-os.org/22.04/amd64/intel/24/pop-os_22.04_amd64_intel_24.iso"
	"username=pop-os noprompt  ---"
	"username=pop-os persistent   "
	"b42773b1502c91906ceb296284a4832bd164bd8af5d096594915cd5cd8f4ac9c"

	"Pop!_OS 22.04 LTS (NVIDIA)"
	"https://iso.pop-os.org/22.04/amd64/nvidia/24/pop-os_22.04_amd64_nvidia_24.iso"
	"username=pop-os noprompt  modules_load=nvidia nvidia-drm.modeset=0 ---"
	"username=pop-os modules_load=nvidia nvidia-drm.modeset=0 persistent   "
	"067894f912f576be874dae9d1fbc0279d98017dc7a416f01eb48fdeb9570e650"

)

echo "Available ISO images:"
IMAGES_COUNT=$(( ${#IMAGES[@]} / 5 ))
for IMAGE_ID in $(seq $IMAGES_COUNT); do
	echo "$IMAGE_ID. ${IMAGES[($IMAGE_ID - 1) * 5]}"
done

read -r -p "Select an image to download: " IMAGE_ID
[[ $IMAGE_ID -eq 0 || $IMAGE_ID -gt $IMAGES_COUNT ]] && exit 1

IMAGE_ID=$(( (IMAGE_ID - 1) * 5 ))
IMAGE_NAME="${IMAGES[$IMAGE_ID]}"
IMAGE_URL="${IMAGES[$IMAGE_ID + 1]}"
IMAGE_PATCH_SRC="${IMAGES[$IMAGE_ID + 2]}"
IMAGE_PATCH_DST="${IMAGES[$IMAGE_ID + 3]}"
IMAGE_SHA256="${IMAGES[$IMAGE_ID + 4]}"
IMAGE_FILE="${IMAGE_URL##*/}"

echo
echo "Downloading $IMAGE_NAME..."
wget --continue --no-verbose --show-progress "$IMAGE_URL"

echo
echo "Patching $IMAGE_NAME..."

gcc -x c -o pop-os-patcher - << EOF
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

int main(int argc, char *argv[]) {

	if (argc != 4) {
		printf("usage: %s <iso> <src> <dst>\n", argv[0]);
		return 1;
	}

	int fd;
	if ((fd = open(argv[1], O_RDWR)) == -1) {
		perror("ERROR: Open ISO");
		return 1;
	}

	size_t len = strlen(argv[2]);
	if (len != strlen(argv[3])) {
		fprintf(stderr, "ERROR: length(src) != length(dst)\n");
		return 1;
	}

	char *data;
	off_t size = lseek(fd, 0, SEEK_END);
	if ((data = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) {
		perror("ERROR: Memory map ISO");
		return 1;
	}

	for (size_t off = 0; off < size - len; off++)
		if (memcmp(&data[off], argv[2], len) == 0) {
			printf("Patching at offset: %#zx\n", off);
			memcpy(&data[off], argv[3], len);
		}

	msync(data, size, MS_SYNC);
	munmap(data, size);
	close(fd);

	return 0;
}
EOF

./pop-os-patcher "$IMAGE_FILE" "$IMAGE_PATCH_SRC" "$IMAGE_PATCH_DST"
rm ./pop-os-patcher

echo
echo "Verifying $IMAGE_NAME..."
echo "$IMAGE_SHA256 $IMAGE_FILE" | sha256sum --check