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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2016 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 builtin
import (
"fmt"
"path/filepath"
"regexp"
"strings"
"github.com/snapcore/snapd/interfaces"
"github.com/snapcore/snapd/interfaces/apparmor"
"github.com/snapcore/snapd/interfaces/udev"
"github.com/snapcore/snapd/snap"
)
const i2cSummary = `allows access to specific I2C controller`
const i2cBaseDeclarationSlots = `
i2c:
allow-installation:
slot-snap-type:
- gadget
- core
deny-auto-connection: true
`
const i2cConnectedPlugAppArmorPath = `
# Description: Can access I2C controller
%s rw,
`
const i2cConnectedPlugAppArmorSysfsName = `
# Description: Can access I2C sysfs name
/sys/bus/i2c/devices/%s/** rw,
`
// The type for i2c interface
type i2cInterface struct{}
// Getter for the name of the i2c interface
func (iface *i2cInterface) Name() string {
return "i2c"
}
func (iface *i2cInterface) StaticInfo() interfaces.StaticInfo {
return interfaces.StaticInfo{
Summary: i2cSummary,
BaseDeclarationSlots: i2cBaseDeclarationSlots,
}
}
func (iface *i2cInterface) String() string {
return iface.Name()
}
// Pattern to match allowed i2c device nodes. It is gonna be used to check the
// validity of the path attributes in case the udev is not used for
// identification
var i2cControlDeviceNodePattern = regexp.MustCompile("^/dev/i2c-[0-9]+$")
// Pattern to match allowed i2c sysfs names.
var i2cValidSysfsName = regexp.MustCompile("^[a-zA-Z0-9_-]+$")
// Check validity of the defined slot
func (iface *i2cInterface) BeforePrepareSlot(slot *snap.SlotInfo) error {
sysfsName, ok := slot.Attrs["sysfs-name"].(string)
if ok {
if !i2cValidSysfsName.MatchString(sysfsName) {
return fmt.Errorf("%s sysfs-name attribute must be a valid sysfs-name", iface.Name())
}
if _, ok := slot.Attrs["path"].(string); ok {
return fmt.Errorf("%s slot can only use path or sysfs-name", iface.Name())
}
return nil
}
// Validate the path
path, ok := slot.Attrs["path"].(string)
if !ok || path == "" {
return fmt.Errorf("%s slot must have a path or sysfs-name attribute", iface.Name())
}
// XXX: this interface feeds the cleaned path into the regex and is
// left unchanged here for historical reasons. New interfaces (eg,
// like raw-volume) should instead use verifySlotPathAttribute() which
// performs additional verification.
path = filepath.Clean(path)
if !i2cControlDeviceNodePattern.MatchString(path) {
return fmt.Errorf("%s path attribute must be a valid device node", iface.Name())
}
return nil
}
func (iface *i2cInterface) AppArmorConnectedPlug(spec *apparmor.Specification, plug *interfaces.ConnectedPlug, slot *interfaces.ConnectedSlot) error {
// check if sysfsName is set and if so stop after that
var sysfsName string
if err := slot.Attr("sysfs-name", &sysfsName); err == nil {
spec.AddSnippet(fmt.Sprintf(i2cConnectedPlugAppArmorSysfsName, sysfsName))
return nil
}
// do path if sysfsName is not set (they can't be set both)
var path string
if err := slot.Attr("path", &path); err != nil {
return nil
}
cleanedPath := filepath.Clean(path)
spec.AddSnippet(fmt.Sprintf(i2cConnectedPlugAppArmorPath, cleanedPath))
// Use parametric snippets to avoid no-expr-simplify side-effects.
spec.AddParametricSnippet([]string{
"/sys/devices/platform/{*,**.i2c}/i2c-" /* ###PARAM### */, "/** rw, # Add any condensed parametric rules",
}, strings.TrimPrefix(path, "/dev/i2c-"))
return nil
}
func (iface *i2cInterface) UDevConnectedPlug(spec *udev.Specification, plug *interfaces.ConnectedPlug, slot *interfaces.ConnectedSlot) error {
var path string
if err := slot.Attr("path", &path); err != nil {
return nil
}
spec.TagDevice(fmt.Sprintf(`KERNEL=="%s"`, strings.TrimPrefix(path, "/dev/")))
return nil
}
func (iface *i2cInterface) AutoConnect(*snap.PlugInfo, *snap.SlotInfo) bool {
// Allow what is allowed in the declarations
return true
}
func init() {
registerIface(&i2cInterface{})
}
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