testsAndMisc/linux_configuration/utils/lib/sd_card_ops.sh

#!/bin/bash
# Argument parsing and the partition/format operations.
#
# Sourced by format_sd_card.sh; split out to keep it under the 250-line cap.
# Sourced rather than run, so it inherits the caller's strict mode and
# the helper functions and variables defined above the source line.

parse_args() {
  DEVICE=""

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --dry-run)
        DRY_RUN=true
        shift
        ;;
      --fs)
        if [[ $# -lt 2 ]]; then
          echo "Missing value for --fs" >&2
          exit 1
        fi
        FILESYSTEM="$2"
        shift 2
        ;;
      --dumbphone)
        # Force settings that are friendlier to older phones:
        # * MBR (dos) partition table
        # * Single ~30GiB FAT32 partition
        # * Leave remaining space unused
        DUMBPHONE_MODE=true
        FILESYSTEM="vfat"
        shift
        ;;
      -h | --help)
        usage
        exit 0
        ;;
      /dev/*)
        DEVICE="$1"
        shift
        ;;
      *)
        echo "Unknown argument: $1" >&2
        usage
        exit 1
        ;;
    esac
  done

  export DEVICE FILESYSTEM DRY_RUN DUMBPHONE_MODE
}

detect_sd_card() {
  # List removable disks (RM=1, TYPE=disk)
  # Columns: NAME, RM, SIZE, MODEL, TRAN, TYPE
  local output
  output=$(lsblk -o NAME,RM,SIZE,MODEL,TRAN,TYPE -nr | awk '$2==1 && $6=="disk"') || true

  if [[ -z $output ]]; then
    echo "No removable disks detected. Please provide device explicitly (e.g., /dev/sda)." >&2
    exit 1
  fi

  mapfile -t candidates < <(echo "$output")

  if [[ ${#candidates[@]} -eq 1 ]]; then
    local name size model tran
    read -r name _ size model tran _ <<< "${candidates[0]}"
    DEVICE="/dev/${name}"
    log "Detected removable disk: $DEVICE (${size} ${model} ${tran})"
  else
    echo "Multiple removable disks detected:" >&2
    local i=1
    for line in "${candidates[@]}"; do
      local name size model tran
      read -r name _ size model tran _ <<< "$line"
      printf '  %d) /dev/%s  %s  %s %s\n' "$i" "$name" "$size" "$model" "$tran"
      ((i++))
    done

    while true; do
      read -r -p "Select device to format (1-${#candidates[@]}): " choice
      if [[ $choice =~ ^[0-9]+$ ]] && ((choice >= 1 && choice <= ${#candidates[@]})); then
        local sel="${candidates[choice - 1]}"
        local name size model tran
        read -r name _ size model tran _ <<< "$sel"
        DEVICE="/dev/${name}"
        log "Selected device: $DEVICE (${size} ${model} ${tran})"
        break
      else
        echo "Invalid choice." >&2
      fi
    done
  fi
}

validate_device() {
  if [[ -z ${DEVICE:-} ]]; then
    detect_sd_card
  fi

  if [[ ! -b $DEVICE ]]; then
    echo "Device $DEVICE does not exist or is not a block device." >&2
    exit 1
  fi

  # Extra safety: refuse clearly system disks by checking if rootfs lives there
  local root_dev
  root_dev=$(findmnt -no SOURCE / || true)
  if [[ $root_dev == "$DEVICE"* ]]; then
    echo "Refusing to operate on $DEVICE because it appears to contain the root filesystem ($root_dev)." >&2
    exit 1
  fi
}

unmount_partitions() {
  local dev base part
  dev="$DEVICE"
  base="${dev##*/}"

  mapfile -t parts < <(lsblk -nr -o NAME,MOUNTPOINT "/dev/${base}" | awk 'NF==2 {print $1" "$2}') || true

  for entry in "${parts[@]:-}"; do
    read -r part mp <<< "$entry"
    if [[ -n $mp ]]; then
      run "umount \"$mp\""
    fi
  done
}

wipe_and_partition() {
  local dev="$DEVICE"

  if ! confirm "About to WIPE ALL DATA on $dev and create a new ${FILESYSTEM} filesystem. Continue?"; then
    echo "Aborted by user." >&2
    exit 1
  fi

  # Zap existing partition table
  run "wipefs -a \"$dev\""

  # Create a new partition table + partition layout
  # Using sfdisk for non-interactive, reproducible layout
  local sfdisk_input

  if [[ $DUMBPHONE_MODE == true ]]; then
    # Old phones often:
    #   * only support MBR (dos)
    #   * only support SD/SDHC (<=32GiB)
    # We create an MBR table and a single ~30GiB FAT32 partition, leaving the rest unused.
    # 30GiB ≈ 30 * 2^30 / 512 ≈ 62914560 sectors; start at 2048 for alignment.
    sfdisk_input=$'label: dos\n2048,62914560,c,*\n'
    if [[ $DRY_RUN == true ]]; then
      log "DRY RUN: echo -e '$sfdisk_input' | sfdisk $dev"
    else
      log "RUN: create MBR (dos) with ~30GiB FAT32 partition on $dev"
      echo -e "$sfdisk_input" | sfdisk "$dev"
    fi
  else
    # Default: GPT with one partition spanning the whole device
    sfdisk_input=$'label: gpt\n,;\n'
    if [[ $DRY_RUN == true ]]; then
      log "DRY RUN: echo -e '$sfdisk_input' | sfdisk $dev"
    else
      log "RUN: create GPT with one partition on $dev"
      echo -e "$sfdisk_input" | sfdisk "$dev"
    fi
  fi

  # Let the kernel re-read the partition table
  sleep 2
}

format_filesystem() {
  local dev base part
  dev="$DEVICE"
  base="${dev##*/}"
  part="/dev/${base}1"

  if [[ ! -b $part ]]; then
    echo "Expected partition $part not found after partitioning." >&2
    exit 1
  fi

  case "$FILESYSTEM" in
    exfat)
      run mkfs.exfat -n SDCARD "$part"
      ;;
    vfat | fat32)
      run mkfs.vfat -F32 -n SDCARD "$part"
      ;;
    ext4)
      run mkfs.ext4 -F -L SDCARD "$part"
      ;;
    *)
      echo "Unsupported filesystem type: $FILESYSTEM" >&2
      exit 1
      ;;
  esac

  log "Formatting completed on $part with filesystem $FILESYSTEM."
}