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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2020 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 wrappers
import (
"bytes"
"os"
"path/filepath"
"regexp"
"text/template"
"github.com/snapcore/snapd/dirs"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/snap"
)
func generateDBusActivationFile(app *snap.AppInfo, busName string) ([]byte, error) {
// The D-Bus service activation file format is defined as part
// of the protocol specification:
//
// https://dbus.freedesktop.org/doc/dbus-specification.html#message-bus-starting-services
serviceTemplate := `[D-BUS Service]
Name={{.BusName}}
Comment=Bus name for snap application {{.App.Snap.InstanceName}}.{{.App.Name}}
SystemdService={{.App.ServiceName}}
Exec={{.App.LauncherCommand}}
AssumedAppArmorLabel={{.App.SecurityTag}}
{{- if eq .App.DaemonScope "system"}}
User=root
{{- end}}
X-Snap={{.App.Snap.InstanceName}}
`
t := template.Must(template.New("dbus-service").Parse(serviceTemplate))
serviceData := struct {
App *snap.AppInfo
BusName string
}{
App: app,
BusName: busName,
}
var templateOut bytes.Buffer
if err := t.Execute(&templateOut, serviceData); err != nil {
return nil, err
}
return templateOut.Bytes(), nil
}
var snapNameLine = regexp.MustCompile(`(?m)^X-Snap=(.*)$`)
// snapNameFromServiceFile returns the snap name for the D-Bus service activation file.
func snapNameFromServiceFile(filename string) (owner string, err error) {
content, err := os.ReadFile(filename)
if err != nil {
return "", err
}
m := snapNameLine.FindSubmatch(content)
if m != nil {
owner = string(m[1])
}
return owner, nil
}
// snapServiceActivationFiles returns the list of service activation files for a snap.
func snapServiceActivationFiles(dir, snapName string) (services []string, err error) {
glob := filepath.Join(dir, "*.service")
matches, err := filepath.Glob(glob)
if err != nil {
return nil, err
}
for _, match := range matches {
serviceSnap, err := snapNameFromServiceFile(match)
if err != nil {
return nil, err
}
if serviceSnap == snapName {
services = append(services, filepath.Base(match))
}
}
return services, nil
}
func AddSnapDBusActivationFiles(s *snap.Info) error {
if err := os.MkdirAll(dirs.SnapDBusSessionServicesDir, 0755); err != nil {
return err
}
if err := os.MkdirAll(dirs.SnapDBusSystemServicesDir, 0755); err != nil {
return err
}
// Make sure we include any service files that claim to have
// been written by the snap.
sessionServices, err := snapServiceActivationFiles(dirs.SnapDBusSessionServicesDir, s.InstanceName())
if err != nil {
return err
}
systemServices, err := snapServiceActivationFiles(dirs.SnapDBusSystemServicesDir, s.InstanceName())
if err != nil {
return err
}
sessionContent := make(map[string]osutil.FileState)
systemContent := make(map[string]osutil.FileState)
for _, app := range s.Apps {
if !app.IsService() {
continue
}
for _, slot := range app.ActivatesOn {
var busName string
if err := slot.Attr("name", &busName); err != nil {
return err
}
content, err := generateDBusActivationFile(app, busName)
if err != nil {
return err
}
filename := busName + ".service"
fileState := &osutil.MemoryFileState{
Content: content,
Mode: 0644,
}
switch app.DaemonScope {
case snap.SystemDaemon:
systemContent[filename] = fileState
systemServices = append(systemServices, filename)
case snap.UserDaemon:
sessionContent[filename] = fileState
sessionServices = append(sessionServices, filename)
}
}
}
if _, _, err = osutil.EnsureDirStateGlobs(dirs.SnapDBusSessionServicesDir, sessionServices, sessionContent); err != nil {
return err
}
if _, _, err = osutil.EnsureDirStateGlobs(dirs.SnapDBusSystemServicesDir, systemServices, systemContent); err != nil {
// On error, remove files installed by first invocation
osutil.EnsureDirStateGlobs(dirs.SnapDBusSessionServicesDir, sessionServices, nil)
return err
}
return nil
}
func RemoveSnapDBusActivationFiles(s *snap.Info) error {
// Select files to delete via X-Snap line to ensure everything
// is cleaned up if "snap try" is used and snap.yaml is
// modified.
for _, servicesDir := range []string{
dirs.SnapDBusSessionServicesDir,
dirs.SnapDBusSystemServicesDir,
} {
toRemove, err := snapServiceActivationFiles(servicesDir, s.InstanceName())
if err != nil {
return err
}
if _, _, err = osutil.EnsureDirStateGlobs(servicesDir, toRemove, nil); err != nil {
return err
}
}
return nil
}
|
