#
# Settings and functions for shell scripts.
#

CONFIG_PARTITION=mmcblk0p2
CONFIG_MOUNTPOINT=/mnt/cfg
CONFIG_DIR=/var/lib/puzzlefw/cfg

# Lock the configuration files.
lock_config() {

    # Make config directory in RAM filesystem.
    mkdir -p $CONFIG_DIR

    # Create or open lock file.
    # The file remains open until the calling script ends.
    exec 3>>${CONFIG_DIR}/lockfile

    # Get exclusive lock on the file.
    if ! flock -n 3 ; then
        echo "ERROR: Configuration locked" >&2
        return 1
    fi
}

# Read configuration files from the SD card.
# This is only used during boot.
read_config() {

    # Mount config filesystem read-only.
    mkdir -p $CONFIG_MOUNTPOINT
    mount -t ext4 -r -o noatime,data=journal /dev/${CONFIG_PARTITION} $CONFIG_MOUNTPOINT || return 1

    # Copy config files to RAM filesystem.
    cp -a ${CONFIG_MOUNTPOINT}/*.conf $CONFIG_DIR

    umount $CONFIG_MOUNTPOINT
}

# Write changed configuration files to the SD card.
# Parameters: names of config files to synchronize
sync_config() {

    # Mount config filesystem.
    mkdir -p $CONFIG_MOUNTPOINT
    mount -t ext4 -o noatime,data=journal /dev/${CONFIG_PARTITION} $CONFIG_MOUNTPOINT || return 1

    for fname in "$@" ; do

        # Copy new version of file to SD card.
        cp ${CONFIG_DIR}/${fname}.new $CONFIG_MOUNTPOINT

	# Atomically replace the old file on the SD card.
	mv ${CONFIG_MOUNTPOINT}/${fname}.new ${CONFIG_MOUNTPOINT}/${fname}

	# Replace the old file in the RAM filesystem.
	mv ${CONFIG_DIR}/${fname}.new ${CONFIG_DIR}/${fname}
    done

    umount $CONFIG_MOUNTPOINT
    sync
}