github.com/kubiko/snapd@v0.0.0-20201013125620-d4f3094d9ddf/cmd/snap/cmd_connections.go

// -*- Mode: Go; indent-tabs-mode: t -*-

/*
 * Copyright (C) 2018 Canonical Ltd
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package main

import (
	"fmt"
	"sort"
	"strings"

	"github.com/jessevdk/go-flags"

	"github.com/snapcore/snapd/client"
	"github.com/snapcore/snapd/i18n"
)

type cmdConnections struct {
	clientMixin
	All         bool `long:"all"`
	Positionals struct {
		Snap installedSnapName
	} `positional-args:"true"`
}

var shortConnectionsHelp = i18n.G("List interface connections")
var longConnectionsHelp = i18n.G(`
The connections command lists connections between plugs and slots
in the system.

Unless <snap> is provided, the listing is for connected plugs and
slots for all snaps in the system. In this mode, pass --all to also
list unconnected plugs and slots.

$ snap connections <snap>

Lists connected and unconnected plugs and slots for the specified
snap.
`)

func init() {
	addCommand("connections", shortConnectionsHelp, longConnectionsHelp, func() flags.Commander {
		return &cmdConnections{}
	}, map[string]string{
		"all": i18n.G("Show connected and unconnected plugs and slots"),
	}, []argDesc{{
		// TRANSLATORS: This needs to be wrapped in <>s.
		name: "<snap>",
		// TRANSLATORS: This should not start with a lowercase letter.
		desc: i18n.G("Constrain listing to a specific snap"),
	}})
}

func isSystemSnap(snap string) bool {
	return snap == "core" || snap == "snapd" || snap == "system"
}

func endpoint(snap, name string) string {
	if isSystemSnap(snap) {
		return ":" + name
	}
	return snap + ":" + name
}

type connection struct {
	slot                 string
	plug                 string
	interfaceName        string
	interfaceDeterminant string
	manual               bool
	gadget               bool
}

func (cn connection) String() string {
	opts := []string{}
	if cn.manual {
		opts = append(opts, "manual")
	}
	if cn.gadget {
		opts = append(opts, "gadget")
	}
	if len(opts) == 0 {
		return "-"
	}
	return strings.Join(opts, ",")
}

type byConnectionData []connection

func (b byConnectionData) Len() int      { return len(b) }
func (b byConnectionData) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b byConnectionData) Less(i, j int) bool {
	iCon, jCon := b[i], b[j]
	if iCon.interfaceName != jCon.interfaceName {
		return iCon.interfaceName < jCon.interfaceName
	}
	if iCon.plug != jCon.plug {
		return iCon.plug < jCon.plug
	}
	return iCon.slot < jCon.slot
}

func interfaceDeterminant(conn *client.Connection) string {
	var value string

	switch conn.Interface {
	case "content":
		value, _ = conn.PlugAttrs["content"].(string)
		if value == "" {
			value, _ = conn.SlotAttrs["content"].(string)
		}
	}
	if value == "" {
		return ""
	}
	return fmt.Sprintf("[%v]", value)
}

func (x *cmdConnections) Execute(args []string) error {
	if len(args) > 0 {
		return ErrExtraArgs
	}

	opts := client.ConnectionOptions{
		All: x.All,
	}
	wanted := string(x.Positionals.Snap)
	if wanted != "" {
		if x.All {
			// passing a snap name already implies --all, error out
			// when it was passed explicitly
			return fmt.Errorf(i18n.G("cannot use --all with snap name"))
		}
		// when asking for a single snap, include its disconnected plugs
		// and slots
		opts.Snap = wanted
		opts.All = true
		// print all slots
		x.All = true
	}

	connections, err := x.client.Connections(&opts)
	if err != nil {
		return err
	}
	if len(connections.Plugs) == 0 && len(connections.Slots) == 0 {
		return nil
	}

	annotatedConns := make([]connection, 0, len(connections.Established)+len(connections.Undesired))
	for _, conn := range connections.Established {
		annotatedConns = append(annotatedConns, connection{
			plug:                 endpoint(conn.Plug.Snap, conn.Plug.Name),
			slot:                 endpoint(conn.Slot.Snap, conn.Slot.Name),
			manual:               conn.Manual,
			gadget:               conn.Gadget,
			interfaceName:        conn.Interface,
			interfaceDeterminant: interfaceDeterminant(&conn),
		})
	}

	w := tabWriter()
	fmt.Fprintln(w, i18n.G("Interface\tPlug\tSlot\tNotes"))

	for _, plug := range connections.Plugs {
		if len(plug.Connections) == 0 && x.All {
			annotatedConns = append(annotatedConns, connection{
				plug:          endpoint(plug.Snap, plug.Name),
				slot:          "-",
				interfaceName: plug.Interface,
			})
		}
	}
	for _, slot := range connections.Slots {
		if !isSystemSnap(wanted) && isSystemSnap(slot.Snap) {
			// displaying unconnected system snap slots is boring,
			// unless explicitly asked to show them
			continue
		}
		if len(slot.Connections) == 0 && x.All {
			annotatedConns = append(annotatedConns, connection{
				plug:          "-",
				slot:          endpoint(slot.Snap, slot.Name),
				interfaceName: slot.Interface,
			})
		}
	}

	sort.Sort(byConnectionData(annotatedConns))

	for _, note := range annotatedConns {
		fmt.Fprintf(w, "%s%s\t%s\t%s\t%s\n", note.interfaceName, note.interfaceDeterminant, note.plug, note.slot, note)
	}

	if len(annotatedConns) > 0 {
		w.Flush()
	}
	return nil
}