From d32d305d3ba6fd30139108ca18e4b5d728111a5e Mon Sep 17 00:00:00 2001
From: Krzysztof kuhy Rudnicki <krzysztofrudnicki0@gmail.com>
Date: Fri, 14 Nov 2025 14:49:51 +0100
Subject: [PATCH] feat: script for formatting sd card

---
 scripts/utils/format_sd_card.sh | 323 ++++++++++++++++++++++++++++++++
 1 file changed, 323 insertions(+)
 create mode 100755 scripts/utils/format_sd_card.sh

diff --git a/scripts/utils/format_sd_card.sh b/scripts/utils/format_sd_card.sh
new file mode 100755
index 0000000..d745792
--- /dev/null
+++ b/scripts/utils/format_sd_card.sh
@@ -0,0 +1,323 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# format_sd_card.sh
+#
+# Safely detect and format an SD card.
+#
+# Defaults:
+#   * Detect removable disks via lsblk (TYPE=disk, RM=1)
+#   * Interactive selection if multiple candidates found
+#   * Unmount all partitions before formatting
+#   * Create a single partition and format it as exfat by default
+#
+# Usage:
+#   sudo ./format_sd_card.sh              # interactive detection + confirmation
+#   sudo ./format_sd_card.sh /dev/sdX     # format specific device
+#   sudo ./format_sd_card.sh --dry-run    # show what would happen, no changes
+#   sudo ./format_sd_card.sh --help
+
+DRY_RUN=false
+FILESYSTEM="exfat"   # you can change to ext4, vfat, etc.
+DUMBPHONE_MODE=false # when true: MBR + ~30GiB FAT32 primary partition
+
+log() {
+  printf '[%s] %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*"
+}
+
+usage() {
+  cat << EOF
+Usage: sudo $(basename "$0") [OPTIONS] [DEVICE]
+
+Safely detect and format an SD card.
+
+Options:
+  --dry-run       Show actions without executing them
+  --fs TYPE       Filesystem type (default: ${FILESYSTEM})
+  --dumbphone     Use MBR and create a ~30GiB FAT32 partition for old phones
+  -h, --help      Show this help
+
+If DEVICE is not provided, removable disks are detected automatically and you
+will be asked to pick one if multiple are found.
+
+WARNING: This will ERASE ALL DATA on the selected device.
+EOF
+}
+
+ensure_fs_tools() {
+  case "$FILESYSTEM" in
+    vfat | fat32)
+      # Ensure mkfs.vfat is available
+      if ! command -v mkfs.vfat > /dev/null 2>&1; then
+        echo "mkfs.vfat not found. Attempting to install dosfstools..." >&2
+
+        # Detect package manager
+        if command -v pacman > /dev/null 2>&1; then
+          run "pacman -Sy --needed --noconfirm dosfstools"
+        elif command -v apt-get > /dev/null 2>&1; then
+          run "apt-get update"
+          run "apt-get install -y dosfstools"
+        else
+          echo "Unsupported package manager. Please install 'dosfstools' (provides mkfs.vfat) manually." >&2
+          exit 1
+        fi
+
+        # Re-check
+        if ! command -v mkfs.vfat > /dev/null 2>&1; then
+          echo "mkfs.vfat is still not available after attempted installation." >&2
+          exit 1
+        fi
+      fi
+      ;;
+    exfat)
+      # exfat tools
+      if ! command -v mkfs.exfat > /dev/null 2>&1; then
+        echo "mkfs.exfat not found. Please install exfatprogs (Arch) or exfat-fuse/exfatprogs (Debian/Ubuntu)." >&2
+        # Do not auto-install here to avoid too much magic across distros
+        exit 1
+      fi
+      ;;
+    ext4)
+      if ! command -v mkfs.ext4 > /dev/null 2>&1; then
+        echo "mkfs.ext4 not found. Please install e2fsprogs." >&2
+        exit 1
+      fi
+      ;;
+  esac
+}
+
+require_root() {
+  if [[ ${EUID:-$(id -u)} -ne 0 ]]; then
+    echo "This script must be run as root (use sudo)." >&2
+    exit 1
+  fi
+}
+
+run() {
+  if [[ $DRY_RUN == true ]]; then
+    log "DRY RUN: $*"
+  else
+    log "RUN: $*"
+    "$@"
+  fi
+}
+
+confirm() {
+  local prompt="$1"
+  read -r -p "$prompt [y/N]: " ans
+  case "$ans" in
+    y | Y | yes | YES) return 0 ;;
+    *) return 1 ;;
+  esac
+}
+
+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 $FILESYSTEM."
+}
+
+main() {
+  parse_args "$@"
+  require_root
+  ensure_fs_tools
+  validate_device
+  unmount_partitions
+  wipe_and_partition
+  format_filesystem
+
+  log "All done. You can now remove and reinsert the SD card or mount the new filesystem manually."
+}
+
+main "$@"