plugin

#!/bin/sh
#
# Run a plugin within the sandbox environment.
# The plugin can be given as a relative name (containing no slash), if the plugin within the
# sandbox should be used.
# If the plugin is given as a filepath (containing a slash), it is symlinked into the sandbox and
# removed after being executed.
#
# The plugin can be executed with its original name (via "run") or in a symlink configuration
# (via "run_as").
#
# Capabilities can be enabled via environment variables:
#   export MUNIN_CAP_MULTIGRAPH=1
#   export MUNIN_CAP_DIRTYCONFIG=1
#

set -eu


STARTPATH=$(pwd)
FINDBIN=$(cd -- "$(dirname "$0")" && pwd)
. "${FINDBIN}/common.sh"

if [ ! -d "$SANDBOX" ]; then
    echo >&2 "Directory '$SANDBOX' does not exist - maybe you need to run '$FINDBIN/install' before"
    exit 1
fi


# Run a plugin from within or outside the sandbox.
# Optionally a symlink configuration may be used.
# Parameters:
#     wanted_plugin_name: the flat basename to be used for executing the plugin
#     wanted_plugin_path: the path of the plugin (external plugins) or its name (in the sandbox)
#     [optional]: all other parameters are handed over to the plugin (e.g. "config" or "suggest")
# The 'wanted_plugin_name' is temporarily created as a symlink within the sandbox
# (below etc/plugins/). Afterwards the previous state is restored.
run_plugin() {
    local wanted_plugin_name="$1"
    local wanted_plugin_path="$2"
    shift 2
    local plugin_name
    local symlink_filename
    local abs_wanted_plugin_path
    if echo "$wanted_plugin_path" | grep -q /; then
        # An external plugin (outside of the sandbox) was specified with its path.
        abs_wanted_plugin_path=$(cd "$STARTPATH"; realpath "$wanted_plugin_path")
    elif [ "$wanted_plugin_name" != "$wanted_plugin_path" ]; then
        # An internal plugin (within the sandbox) should be run as a different name
        # (symlink configuration).
        abs_wanted_plugin_path="$SANDBOX/share/plugins/$wanted_plugin_path"
    else
        abs_wanted_plugin_path=
    fi
    # A symlink is required for external plugins and for a symlink-configured plugin.
    if [ -n "$abs_wanted_plugin_path" ]; then
        symlink_filename="$CONFDIR/plugins/$wanted_plugin_name"
        # move a potential previous file away
        mv "$symlink_filename" "$symlink_filename~" 2>/dev/null || true
        trap "mv '$symlink_filename~' '$symlink_filename' 2>/dev/null || true" EXIT
        ln -s "$abs_wanted_plugin_path" "$symlink_filename"
        "$BASEDIR/dev_scripts/run" munin-run "$wanted_plugin_name" "$@"
        # restore the previous file or at least remove the fresh symlink
        mv "$symlink_filename~" "$symlink_filename" 2>/dev/null || rm -f "$symlink_filename"
        trap "" EXIT
    else
        "$BASEDIR/dev_scripts/run" munin-run "$wanted_plugin_name" "$@"
    fi
}


if [ $# -ge 1 ]; then
    ACTION=$1
    shift
else
    ACTION="help"
fi

case "$ACTION" in
    run)
        if [ $# -lt 1 ]; then
            echo >&2 "Missing parameter: NAME_OR_PATH"
            exit 1
        fi
        run_plugin "$(basename "$1")" "$@"
        ;;
    run_as)
        if [ $# -lt 2 ]; then
            echo >&2 "Missing parameter: RUN_AS_NAME SOURCE_NAME_OR_PATH"
            exit 1
        fi
	if echo "$1" | grep -q /; then
            echo >&2 "Invalid parameter: RUN_AS_NAME must be a relative name (e.g. 'if_eth0')"
            exit 1
        fi
        run_plugin "$@"
        ;;
    help)
        echo "Syntax:  $(basename "$0")  { run | run_as | help }"
	echo
	echo "    run     NAME_OR_PATH  [ARGS]"
	echo "    run_as  RUN_AS_NAME  SOURCE_NAME_OR_PATH  [ARGS]"
        echo
        ;;
    *)
        "$0" help >&2
        exit 1
        ;;
esac