cmd/snap-gpio-helper: add gpio-chardev export/unexport commands

cmd/snap-gpio-helper/cmd_export.go

@@ -20,7 +20,14 @@
 package main
 
 import (
-	"errors"
+	"context"
+	"fmt"
+	"os"
+	"os/signal"
+	"strings"
+
+	"github.com/snapcore/snapd/sandbox/gpio"
+	"github.com/snapcore/snapd/strutil"
 )
 
 type cmdExportChardev struct {
@@ -32,6 +39,17 @@ type cmdExportChardev struct {
 	} `positional-args:"yes" required:"true"`
 }
 
+var gpioExportGadgetChardevChip = gpio.ExportGadgetChardevChip
+
 func (c *cmdExportChardev) Execute(args []string) error {
-	return errors.New("not implemented")
+	chipLabels := strings.Split(c.Args.ChipLabels, ",")
+	lines, err := strutil.ParseRange(c.Args.Lines)
+	if err != nil {
+		return fmt.Errorf("invalid lines argument: %w", err)
+	}
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer stop()
+
+	return gpioExportGadgetChardevChip(ctx, chipLabels, lines, c.Args.Gadget, c.Args.Slot)
 }

cmd/snap-gpio-helper/cmd_export_test.go

@@ -0,0 +1,75 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2025 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_test
+
+import (
+	"context"
+
+	. "gopkg.in/check.v1"
+
+	main "github.com/snapcore/snapd/cmd/snap-gpio-helper"
+	"github.com/snapcore/snapd/strutil"
+)
+
+func (s *snapGpioHelperSuite) TestExportGpioChardevBadLine(c *C) {
+	called := 0
+	restore := main.MockGpioExportGadgetChardevChip(func(ctx context.Context, chipLabels []string, lines strutil.Range, gadgetName, slotName string) error {
+		called++
+		return nil
+	})
+	defer restore()
+
+	for lines, expectedErr := range map[string]string{
+		"0-2,1": `invalid lines argument: overlapping range span found "1"`,
+		"1-0":   `invalid lines argument: invalid range span "1-0": ends before it starts`,
+		"0-":    `invalid lines argument: .*: invalid syntax`,
+		"a":     `invalid lines argument: .*: invalid syntax`,
+	} {
+		err := main.Run([]string{
+			"export-chardev", "label-0", lines, "gadget-name", "slot-name",
+		})
+		c.Check(err, ErrorMatches, expectedErr)
+	}
+
+	c.Assert(called, Equals, 0)
+}
+
+func (s *snapGpioHelperSuite) TestExportGpioChardev(c *C) {
+	called := 0
+	restore := main.MockGpioExportGadgetChardevChip(func(ctx context.Context, chipLabels []string, lines strutil.Range, gadgetName, slotName string) error {
+		called++
+		c.Check(chipLabels, DeepEquals, []string{"label-0", "label-1"})
+		c.Check(lines, DeepEquals, strutil.Range{
+			{Start: 0, End: 6},
+			{Start: 7, End: 7},
+			{Start: 8, End: 100},
+		})
+		c.Check(gadgetName, Equals, "gadget-name")
+		c.Check(slotName, Equals, "slot-name")
+		return nil
+	})
+	defer restore()
+
+	err := main.Run([]string{
+		"export-chardev", "label-0,label-1", "7,0-6,8-100", "gadget-name", "slot-name",
+	})
+	c.Check(err, IsNil)
+	c.Assert(called, Equals, 1)
+}

cmd/snap-gpio-helper/cmd_unexport.go

@@ -19,7 +19,7 @@
 
 package main
 
-import "errors"
+import "github.com/snapcore/snapd/sandbox/gpio"
 
 type cmdUnexportChardev struct {
 	Args struct {
@@ -30,6 +30,8 @@ type cmdUnexportChardev struct {
 	} `positional-args:"yes" required:"true"`
 }
 
+var gpioUnexportGadgetChardevChip = gpio.UnexportGadgetChardevChip
+
 func (c *cmdUnexportChardev) Execute(args []string) error {
-	return errors.New("not implemented")
+	return gpioUnexportGadgetChardevChip(c.Args.Gadget, c.Args.Slot)
 }

cmd/snap-gpio-helper/cmd_unexport_test.go

@@ -0,0 +1,43 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2025 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_test
+
+import (
+	. "gopkg.in/check.v1"
+
+	main "github.com/snapcore/snapd/cmd/snap-gpio-helper"
+)
+
+func (s *snapGpioHelperSuite) TestUnexportGpioChardev(c *C) {
+	called := 0
+	restore := main.MockGpioUnxportGadgetChardevChip(func(gadgetName, slotName string) error {
+		called++
+		c.Check(gadgetName, Equals, "gadget-name")
+		c.Check(slotName, Equals, "slot-name")
+		return nil
+	})
+	defer restore()
+
+	err := main.Run([]string{
+		"unexport-chardev", "label-0,label-1", "7,0-6,8-100", "gadget-name", "slot-name",
+	})
+	c.Check(err, IsNil)
+	c.Assert(called, Equals, 1)
+}

cmd/snap-gpio-helper/export_test.go

@@ -0,0 +1,38 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2025 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 (
+	"context"
+
+	"github.com/snapcore/snapd/strutil"
+	"github.com/snapcore/snapd/testutil"
+)
+
+var (
+	Run = run
+)
+
+func MockGpioExportGadgetChardevChip(f func(ctx context.Context, chipLabels []string, lines strutil.Range, gadgetName string, slotName string) error) (restore func()) {
+	return testutil.Mock(&gpioExportGadgetChardevChip, f)
+}
+
+func MockGpioUnxportGadgetChardevChip(f func(gadgetName string, slotName string) error) (restore func()) {
+	return testutil.Mock(&gpioUnexportGadgetChardevChip, f)
+}

cmd/snap-gpio-helper/main.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/jessevdk/go-flags"
 
+	"github.com/snapcore/snapd/features"
 	"github.com/snapcore/snapd/snapdtool"
 )
 
@@ -33,11 +34,16 @@ type options struct {
 	CmdUnexportChardev cmdUnexportChardev `command:"unexport-chardev"`
 }
 
-func run(osArgs1 []string) error {
+func run(args []string) error {
+	if !features.GPIOChardevInterface.IsEnabled() {
+		_, flag := features.GPIOChardevInterface.ConfigOption()
+		return fmt.Errorf("gpio-chardev interface requires the %q flag to be set", flag)
+	}
+
 	var opts options
 	p := flags.NewParser(&opts, flags.HelpFlag|flags.PassDoubleDash)
 
-	if _, err := p.ParseArgs(osArgs1); err != nil {
+	if _, err := p.ParseArgs(args); err != nil {
 		return err
 	}
 	return nil

cmd/snap-gpio-helper/main_test.go

@@ -0,0 +1,64 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2025 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_test
+
+import (
+	"os"
+	"testing"
+
+	. "gopkg.in/check.v1"
+
+	main "github.com/snapcore/snapd/cmd/snap-gpio-helper"
+	"github.com/snapcore/snapd/dirs"
+	"github.com/snapcore/snapd/features"
+	"github.com/snapcore/snapd/testutil"
+)
+
+// Hook up check.v1 into the "go test" runner
+func Test(t *testing.T) { TestingT(t) }
+
+type snapGpioHelperSuite struct {
+	testutil.BaseTest
+}
+
+var _ = Suite(&snapGpioHelperSuite{})
+
+func (s *snapGpioHelperSuite) SetUpTest(c *C) {
+	dirs.SetRootDir(c.MkDir())
+	s.AddCleanup(func() { dirs.SetRootDir("") })
+
+	// Mock experimental.gpio-chardev-interface
+	c.Assert(os.MkdirAll(dirs.FeaturesDir, 0755), IsNil)
+	c.Assert(os.WriteFile(features.GPIOChardevInterface.ControlFile(), []byte(nil), 0644), IsNil)
+}
+
+func (s *snapGpioHelperSuite) TestGpioChardevExperimentlFlagUnset(c *C) {
+	c.Assert(os.RemoveAll(features.GPIOChardevInterface.ControlFile()), IsNil)
+
+	err := main.Run([]string{
+		"export-chardev", "label-0", "0,2", "gadget-name", "slot-name",
+	})
+	c.Check(err, ErrorMatches, `gpio-chardev interface requires the "experimental.gpio-chardev-interface" flag to be set`)
+
+	err = main.Run([]string{
+		"unexport-chardev", "label-0", "0,2", "gadget-name", "slot-name",
+	})
+	c.Check(err, ErrorMatches, `gpio-chardev interface requires the "experimental.gpio-chardev-interface" flag to be set`)
+}

dirs/dirs.go

@@ -127,6 +127,8 @@ var (
 	SnapDeviceSaveDir string
 	SnapDataSaveDir   string
 
+	SnapGpioChardevDir string
+
 	CloudMetaDataFile     string
 	CloudInstanceDataFile string
 
@@ -148,6 +150,8 @@ var (
 
 	SysfsDir string
 
+	DevDir string
+
 	FeaturesDir string
 
 	// WritableMountPath is a path where writable root data is
@@ -642,6 +646,9 @@ func SetRootDir(rootdir string) {
 	SnapKModModulesDir = filepath.Join(rootdir, "/etc/modules-load.d/")
 	SnapKModModprobeDir = filepath.Join(rootdir, "/etc/modprobe.d/")
 
+	DevDir = filepath.Join(rootdir, "/dev")
+	SnapGpioChardevDir = filepath.Join(DevDir, "/snap/gpio-chardev")
+
 	LocaleDir = filepath.Join(rootdir, "/usr/share/locale")
 	ClassicDir = filepath.Join(rootdir, "/writable/classic")
 

interfaces/builtin/gpio_chardev.go

@@ -31,6 +31,7 @@ import (
 	"github.com/snapcore/snapd/interfaces/apparmor"
 	"github.com/snapcore/snapd/interfaces/systemd"
 	"github.com/snapcore/snapd/interfaces/udev"
+	"github.com/snapcore/snapd/sandbox/gpio"
 	"github.com/snapcore/snapd/snap"
 	"github.com/snapcore/snapd/strutil"
 )
@@ -165,8 +166,8 @@ func (iface *gpioChardevInterface) SystemdConnectedPlug(spec *systemd.Specificat
 	plugName := plug.Name()
 	plugSnapName := plug.Snap().InstanceName()
 
-	target := filepath.Join("/dev/snap/gpio-chardev", slotSnapName, slotName)
-	symlink := filepath.Join("/dev/snap/gpio-chardev", plugSnapName, plugName)
+	target := gpio.SnapChardevPath(slotSnapName, slotName)
+	symlink := gpio.SnapChardevPath(plugSnapName, plugName)
 
 	// Create symlink pointing to exported virtual slot device.
 	serviceSuffix := fmt.Sprintf("gpio-chardev-%s", plugName)

interfaces/builtin/gpio_chardev_test.go

@@ -228,8 +228,8 @@ func (s *GpioChardevInterfaceSuite) TestSystemdConnectedPlug(c *C) {
 	err := spec.AddConnectedPlug(s.iface, s.plug, s.slot)
 	c.Assert(err, IsNil)
 
-	target := "/dev/snap/gpio-chardev/my-device/gpio-chardev-good-slot"
-	symlink := "/dev/snap/gpio-chardev/consumer/gpio-chardev-good-plug"
+	target := fmt.Sprintf("%s/my-device/gpio-chardev-good-slot", dirs.SnapGpioChardevDir)
+	symlink := fmt.Sprintf("%s/consumer/gpio-chardev-good-plug", dirs.SnapGpioChardevDir)
 
 	expectedExecStart := fmt.Sprintf("/bin/sh -c 'mkdir -p %q && ln -s %q %q'", filepath.Dir(symlink), target, symlink)
 	expectedExecStop := fmt.Sprintf("/bin/rm -f %q", symlink)

osutil/inotify/inotify_others.go

@@ -28,6 +28,8 @@ var errNotSupported = fmt.Errorf("watch not supported on %s", runtime.GOOS)
 const (
 	InDelete     uint32 = 0
 	InDeleteSelf uint32 = 0
+	InCreate     uint32 = 0
+	InCloseWrite uint32 = 0
 )
 
 // NewWatcher creates and returns a new inotify instance using inotify_init(2)

osutil/stat.go

@@ -1,7 +1,7 @@
 // -*- Mode: Go; indent-tabs-mode: t -*-
 
 /*
- * Copyright (C) 2014-2015 Canonical Ltd
+ * Copyright (C) 2014-2025 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

osutil/stat_test.go

@@ -1,7 +1,7 @@
 // -*- Mode: Go; indent-tabs-mode: t -*-
 
 /*
- * Copyright (C) 2014-2015 Canonical Ltd
+ * Copyright (C) 2014-2025 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