Linux_post_install/bin/pos-share-smb-client

#!/usr/bin/env bash
set -euo pipefail
# POS: share smb-client — Mount SMB/CIFS shares (ephemeral or persistent systemd mount units)

source "$(dirname "$0")/../lib/common.sh" 2>/dev/null || source "$(dirname "$0")/common.sh"
source "$(dirname "$0")/../lib/notify.sh" 2>/dev/null || source "$(dirname "$0")/notify.sh"

SMB_CREDS_DIR="${SMB_CREDS_DIR:-/etc/samba/credentials}"
UNIT_DIR="${UNIT_DIR:-/etc/systemd/system}"
command -v mount.cifs &>/dev/null || err "mount.cifs not found (install cifs-utils)"
command -v systemd-escape &>/dev/null || err "systemd-escape not found"

usage() {
    cat <<EOF
Usage: pos share smb-client <command> [args]

Mount and manage SMB/CIFS shares from remote servers (cifs-utils).

Commands:
  mount <//server/share> <local-dir> [user]   One-shot mount (creates local-dir if needed)
  unmount <local-dir>                          Unmount the share
  list                                         Show active + persistent SMB mounts
  persist <//server/share> <local-dir> [user]  Persistent mount via systemd .mount + .automount
                                               units (mounts on first access — never blocks boot)
  unpersist <local-dir>                        Stop, disable and remove the mount/automount units

With no user, guest access is attempted. With a user, you are prompted for
the Samba password — one-shot mounts use a throwaway chmod-600 credentials
file; persistent mounts keep one at /etc/samba/credentials/.

Examples:
  pos share smb-client mount //100.100.100.1/media /mnt/smb/media
  pos share smb-client persist //100.100.100.1/media /mnt/smb/media bob
  pos share smb-client list
  pos share smb-client unmount /mnt/smb/media
EOF
    exit 0
}

cmd="${1:-}"
case "$cmd" in
    -h|--help) usage ;;
    mount|unmount|list|persist|unpersist) ;;
    "") err "Missing command (mount|unmount|list|persist|unpersist)" ;;
    *) err "Unknown command '$cmd' (see --help)" ;;
esac

validate_share() {
    case "$1" in
        //*) ;;
        *) err "Invalid share '$1' — expected <//server/share> (e.g. //10.0.0.5/media)" ;;
    esac
}

validate_dir() {
    case "$1" in
        /*) ;;
        *) err "Mount point must be an absolute path: $1" ;;
    esac
}

# Prompt for the Samba password (no echo, via /dev/tty) and write a fresh
# chmod-600 credentials file; prints its path, caller removes it.
make_creds() {
    local user="$1" pw tmp
    read -rsp "Samba password for $user: " pw </dev/tty || true
    echo >&2
    [ -n "$pw" ] || err "empty password"
    tmp="$(mktemp)"
    chmod 600 "$tmp"
    printf 'username=%s\npassword=%s\n' "$user" "$pw" > "$tmp"
    printf '%s' "$tmp"
}

mount_opts() {
    local user="$1"
    printf 'uid=%s,gid=%s' "$(id -u)" "$(id -g)"
}

case "$cmd" in
    mount)
        what="${2:-}"
        where="${3:-}"
        user="${4:-}"
        [ -n "$what" ] && [ -n "$where" ] || err "Usage: pos share smb-client mount <//server/share> <local-dir> [user]"
        validate_share "$what"
        validate_dir "$where"

        sudo mkdir -p "$where"
        if [ -n "$user" ]; then
            creds="$(make_creds "$user")"
            trap 'rm -f "$creds"' EXIT
            sudo mount -t cifs "$what" "$where" -o "credentials=$creds,$(mount_opts "$user")"
        else
            warn "No user — attempting guest mount (works only if the server allows guest access)"
            sudo mount -t cifs "$what" "$where" -o "guest,$(mount_opts "")"
        fi
        log "Mounted $what at $where"
        ;;

    unmount)
        where="${2:-}"
        [ -n "$where" ] || err "Usage: pos share smb-client unmount <local-dir>"
        validate_dir "$where"

        sudo umount "$where"
        log "Unmounted $where"
        ;;

    list)
        found=0
        active_mounts="$(findmnt -t cifs 2>/dev/null || true)"
        if [ -n "$active_mounts" ]; then
            printf 'Active mounts:\n'
            printf '%s\n' "$active_mounts"
            found=1
        fi
        persistent=()
        for unit in "${UNIT_DIR}"/*.mount; do
            [ -e "$unit" ] || continue
            grep -q '^Type=cifs$' "$unit" || continue
            what="$(sed -n 's/^What=//p' "$unit")"
            where="$(sed -n 's/^Where=//p' "$unit")"
            [ -n "$what" ] && [ -n "$where" ] || continue
            persistent+=("$where|$what")
        done
        if [ "${#persistent[@]}" -gt 0 ]; then
            found=1
            printf 'Persistent (automount):\n'
            for entry in "${persistent[@]}"; do
                printf '  %-44s %s\n' "${entry%%|*}" "${entry#*|}"
            done
        fi
        [ "$found" -eq 1 ] || echo "No SMB mounts"
        ;;

    persist)
        what="${2:-}"
        where="${3:-}"
        user="${4:-}"
        [ -n "$what" ] && [ -n "$where" ] || err "Usage: pos share smb-client persist <//server/share> <local-dir> [user]"
        validate_share "$what"
        validate_dir "$where"

        unit="$(systemd-escape --path --suffix=mount "$where")"
        auto_unit="${unit%.mount}.automount"
        unit_file="${UNIT_DIR}/${unit}"
        auto_file="${UNIT_DIR}/${auto_unit}"
        opts="$(mount_opts "$user"),_netdev,noexec"
        if [ -n "$user" ]; then
            creds_file="$SMB_CREDS_DIR/$(basename "$where")"
            sudo mkdir -p "$SMB_CREDS_DIR"
            tmp="$(make_creds "$user")"
            sudo install -m 600 "$tmp" "$creds_file"
            rm -f "$tmp"
            opts="credentials=$creds_file,$opts"
        else
            warn "No user — persisting a guest mount (works only if the server allows guest access)"
            opts="guest,$opts"
        fi

        sudo mkdir -p "$where"
        cat <<UNIT | sudo tee "$unit_file" >/dev/null
[Unit]
Description=SMB mount of ${what} at ${where}
After=network-online.target
Wants=network-online.target

[Mount]
What=${what}
Where=${where}
Type=cifs
Options=${opts}
UNIT
        cat <<UNIT | sudo tee "$auto_file" >/dev/null
[Unit]
Description=Automount of SMB share ${what} at ${where}

[Automount]
Where=${where}

[Install]
WantedBy=multi-user.target
UNIT
        sudo systemctl daemon-reload
        sudo systemctl enable --now "$auto_unit"
        log "Persistent SMB mount (automount): ${what} → ${where} (${auto_unit})"
        notify_send "SMB mount persisted: ${what} → ${where}"
        ;;

    unpersist)
        where="${2:-}"
        [ -n "$where" ] || err "Usage: pos share smb-client unpersist <local-dir>"
        validate_dir "$where"

        unit="$(systemd-escape --path --suffix=mount "$where")"
        auto_unit="${unit%.mount}.automount"
        unit_file="${UNIT_DIR}/${unit}"
        auto_file="${UNIT_DIR}/${auto_unit}"

        if [ ! -f "$unit_file" ] && [ ! -f "$auto_file" ]; then
            warn "No systemd mount unit for $where (${unit})"
            exit 0
        fi

        sudo systemctl disable "$auto_unit" 2>/dev/null || true
        sudo systemctl stop "$auto_unit" 2>/dev/null || true
        sudo systemctl disable "$unit" 2>/dev/null || true
        sudo systemctl stop "$unit" 2>/dev/null || true
        sudo rm -f "$unit_file" "$auto_file"
        sudo rm -f "$SMB_CREDS_DIR/$(basename "$where")"
        sudo rmdir "$SMB_CREDS_DIR" 2>/dev/null || true
        sudo systemctl daemon-reload
        log "Removed persistent SMB mount: $where"
        notify_send "SMB persistent mount removed: $where"
        ;;
esac