mount-external-disks

#!/bin/bash
#
# Mount external disks
# Automatically discovers USB-connected partitions and handles LUKS encryption
#

set -euo pipefail

MOUNT_BASE="/run/media/dan"
MIN_PARTITION_SIZE=$((1000 * 1024 * 1024))

# Discover USB-connected partitions
discover_usb_partitions() {
    local usb_disks partitions disk part size

    # Find USB disks
    usb_disks=$(lsblk -rno NAME,TYPE,TRAN | awk '$2=="disk" && $3=="usb" {print $1}')

    for disk in $usb_disks; do
        # Find partitions of this disk
        partitions=$(lsblk -rno NAME,TYPE "/dev/$disk" | awk '$2=="part" {print $1}')

        for part in $partitions; do
            # Skip small partitions (EFI, recovery, etc.)
            size=$(lsblk -brno SIZE "/dev/$part" | head -1)
            if [[ "$size" -lt "$MIN_PARTITION_SIZE" ]]; then
                continue
            fi
            echo "/dev/$part"
        done
    done
}

# Check if device is a LUKS container
is_luks() {
    local device="$1"
    sudo cryptsetup isLuks "$device" 2>/dev/null
}

# Get LUKS UUID for a device
get_luks_uuid() {
    local device="$1"
    sudo blkid -o value -s UUID "$device" 2>/dev/null || true
}

# Get filesystem label, fall back to UUID prefix
get_mount_label() {
    local device="$1"
    local label uuid

    label=$(sudo blkid -o value -s LABEL "$device" 2>/dev/null) || true
    if [[ -n "$label" ]]; then
        echo "$label"
        return
    fi

    uuid=$(sudo blkid -o value -s UUID "$device" 2>/dev/null) || true
    if [[ -n "$uuid" ]]; then
        echo "${uuid:0:8}"
        return
    fi

    # Last resort: use device name
    basename "$device"
}

# Check if LUKS container is already open
is_luks_open() {
    local name="$1"
    [[ -e "/dev/mapper/$name" ]]
}

# Check if filesystem is already mounted
is_mounted() {
    local mountpoint="$1"
    mountpoint -q "$mountpoint" 2>/dev/null
}

# Check if any LUKS partitions need opening
any_luks_needs_opening() {
    local partitions partition uuid mapper_name

    partitions=$(discover_usb_partitions)

    for partition in $partitions; do
        if is_luks "$partition"; then
            uuid=$(get_luks_uuid "$partition")
            mapper_name="luks-$uuid"
            if ! is_luks_open "$mapper_name"; then
                return 0
            fi
        fi
    done
    return 1
}

# Mount a partition
mount_disk() {
    local partition="$1"
    local password="${2:-}"
    local uuid mapper_name device label mountpoint

    echo "=== $partition ==="

    if is_luks "$partition"; then
        uuid=$(get_luks_uuid "$partition")
        mapper_name="luks-$uuid"
        device="/dev/mapper/$mapper_name"

        echo "  LUKS encrypted (UUID: $uuid)"

        # Open LUKS container if not already open
        if is_luks_open "$mapper_name"; then
            echo "  LUKS container already open"
        else
            echo "  Opening LUKS container..."
            if [[ -n "$password" ]]; then
                if ! echo "$password" | sudo cryptsetup open "$partition" "$mapper_name"; then
                    echo "  Failed to open LUKS container"
                    return 1
                fi
            else
                if ! sudo cryptsetup open "$partition" "$mapper_name"; then
                    echo "  Failed to open LUKS container"
                    return 1
                fi
            fi
            echo "  LUKS container opened"
        fi

        # Get label from the inner filesystem
        label=$(get_mount_label "$device")
    else
        device="$partition"
        label=$(get_mount_label "$device")
        echo "  Plain filesystem"
    fi

    mountpoint="$MOUNT_BASE/$label"

    # Create mount point if needed
    if [[ ! -d "$mountpoint" ]]; then
        sudo mkdir -p "$mountpoint"
    fi

    # Mount if not already mounted
    if is_mounted "$mountpoint"; then
        echo "  Already mounted at $mountpoint"
    else
        echo "  Mounting to $mountpoint..."
        if ! sudo mount "$device" "$mountpoint"; then
            echo "  Failed to mount"
            return 1
        fi
        echo "  Mounted successfully"
    fi

    return 0
}

main() {
    local partitions partition
    local success=0
    local failed=0
    local password=""

    partitions=$(discover_usb_partitions)

    if [[ -z "$partitions" ]]; then
        echo "No USB partitions found"
        exit 0
    fi

    # Prompt for password once if any LUKS partitions need opening
    if any_luks_needs_opening; then
        read -s -p "Enter LUKS password: " password
        echo
    fi

    for partition in $partitions; do
        if mount_disk "$partition" "$password"; then
            ((++success))
        else
            ((++failed))
        fi
        echo
    done

    echo "Summary: $success mounted, $failed failed"
}

main "$@"