gadget,kernel: add new "kernel" and "gadget/edition" packages

This commit moves the kernel.yaml parsing into the kernel package and extracts the gadget:editionNumber" helper into it's own gadget/editon packages so that it can be shared between the kernel and the gadget packages. Because meta/kernel.yaml is optional it is not an error if it is missing. Extra tests are also added. 

5 files changed, 162 insertions, 45 deletions

diff --git a/gadget/edition/number.go b/gadget/edition/number.go
new file mode 100644
index 0000000000..448b72cf3a
--- /dev/null
+++ b/gadget/edition/number.go
@@ -0,0 +1,42 @@
+// -*- 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 edition
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+)
+
+type Number uint32
+
+func (e *Number) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var es string
+	if err := unmarshal(&es); err != nil {
+	return errors.New(`cannot unmarshal "edition"`)
+	}
+
+	u, err := strconv.ParseUint(es, 10, 32)
+	if err != nil {
+	return fmt.Errorf(`"edition" must be a positive number, not %q`, es)
+	}
+	*e = Number(u)
+	return nil
+}
diff --git a/gadget/edition/number_test.go b/gadget/edition/number_test.go
new file mode 100644
index 0000000000..30cfc184cb
--- /dev/null
+++ b/gadget/edition/number_test.go
@@ -0,0 +1,69 @@
+// -*- 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 edition_test
+
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/yaml.v2"
+
+	"github.com/snapcore/snapd/gadget/edition"
+)
+
+type editionSuite struct{}
+
+var _ = Suite(&editionSuite{})
+
+func TestCommand(t *testing.T) { TestingT(t) }
+
+var mockEditionYaml = []byte(`
+foo:
+ edition: 1
+`)
+
+func (s *editionSuite) TestUnmarshalIntegration(c *C) {
+	type editionStruct struct {
+	Edition edition.Number `yaml:"edition"`
+	}
+
+	for _, tc := range []struct {
+	input string
+	expectedNumber edition.Number
+	expectedErr string
+	}{
+	{"edition: 1", edition.Number(1), ""},
+	{"edition: 0", edition.Number(0), ""},
+	{"edition: 9999999", edition.Number(9999999), ""},
+	{"edition: -1", edition.Number(0), `"edition" must be a positive number, not "-1"`},
+	{"edition: random-string", edition.Number(0), `"edition" must be a positive number, not "random-string"`},
+	{"edition: NaN", edition.Number(0), `"edition" must be a positive number, not "NaN"`},
+	{"edition: 3.14", edition.Number(0), `"edition" must be a positive number, not "3.14"`},
+	} {
+	var en editionStruct
+	err := yaml.Unmarshal([]byte(tc.input), &en)
+	if tc.expectedErr != "" {
+	c.Assert(err, ErrorMatches, tc.expectedErr, Commentf(tc.input))
+	} else {
+	c.Assert(err, IsNil, Commentf(tc.input))
+	c.Check(en.Edition, Equals, tc.expectedNumber, Commentf(tc.input))
+	}
+	}
+}
diff --git a/gadget/gadget.go b/gadget/gadget.go
index 54415a0fff..f860f2cfa3 100644
--- a/gadget/gadget.go
+++ b/gadget/gadget.go
@@ -28,12 +28,12 @@ import (
	"path/filepath"
	"regexp"
	"sort"
-	"strconv"
	"strings"
 
	"gopkg.in/yaml.v2"
 
	"github.com/snapcore/snapd/asserts"
+	"github.com/snapcore/snapd/gadget/edition"
	"github.com/snapcore/snapd/metautil"
	"github.com/snapcore/snapd/snap"
	"github.com/snapcore/snapd/snap/naming"
@@ -206,8 +206,8 @@ func (vc VolumeContent) String() string {
 }
 
 type VolumeUpdate struct {
-	Edition editionNumber `yaml:"edition"`
-	Preserve []string `yaml:"preserve"`
+	Edition edition.Number `yaml:"edition"`
+	Preserve []string `yaml:"preserve"`
 }
 
 // GadgetConnect describes an interface connection requested by the gadget
@@ -787,22 +787,6 @@ func validateStructureUpdate(up *VolumeUpdate, vs *VolumeStructure) error {
	return nil
 }
 
-type editionNumber uint32
-
-func (e *editionNumber) UnmarshalYAML(unmarshal func(interface{}) error) error {
-	var es string
-	if err := unmarshal(&es); err != nil {
-	return errors.New(`cannot unmarshal "edition"`)
-	}
-
-	u, err := strconv.ParseUint(es, 10, 32)
-	if err != nil {
-	return fmt.Errorf(`"edition" must be a positive number, not %q`, es)
-	}
-	*e = editionNumber(u)
-	return nil
-}
-
 // Size describes the size of a structure item or an offset within the
 // structure.
 type Size uint64
diff --git a/gadget/kernel.go b/kernel/kernel.go
index e22744371f..0a9a9f95f5 100644
--- a/gadget/kernel.go
+++ b/kernel/kernel.go
@@ -17,30 +17,31 @@
 *
 */
 
-package gadget
+package kernel
 
 import (
	"fmt"
	"io/ioutil"
+	"os"
	"path/filepath"
 
	"gopkg.in/yaml.v2"
-)
 
-// XXX: should this be in a "gadget/kernel" or "kernel" package?
+	"github.com/snapcore/snapd/gadget/edition"
+)
 
-type KernelAsset struct {
-	Edition editionNumber `yaml:"edition,omitempty"`
-	Content []string `yaml:"content,omitempty"`
+type Asset struct {
+	Edition edition.Number `yaml:"edition,omitempty"`
+	Content []string `yaml:"content,omitempty"`
 }
 
-type KernelInfo struct {
-	Assets map[string]*KernelAsset `yaml:"assets,omitempty"`
+type Info struct {
+	Assets map[string]*Asset `yaml:"assets,omitempty"`
 }
 
-// KernelInfoFromKernelYaml reads the provided kernel metadata.
-func KernelInfoFromKernelYaml(kernelYaml []byte) (*KernelInfo, error) {
-	var ki KernelInfo
+// InfoFromKernelYaml reads the provided kernel metadata.
+func InfoFromKernelYaml(kernelYaml []byte) (*Info, error) {
+	var ki Info
 
	if err := yaml.Unmarshal(kernelYaml, &ki); err != nil {
	return nil, fmt.Errorf("cannot parse kernel metadata: %v", err)
@@ -51,11 +52,16 @@ func KernelInfoFromKernelYaml(kernelYaml []byte) (*KernelInfo, error) {
 
 // ReadInfo reads the kernel specific metadata from meta/kernel.yaml
 // in the snap root directory.
-func ReadKernelInfo(kernelSnapRootDir string) (*KernelInfo, error) {
+func ReadInfo(kernelSnapRootDir string) (*Info, error) {
	p := filepath.Join(kernelSnapRootDir, "meta", "kernel.yaml")
	content, err := ioutil.ReadFile(p)
+	// meta/kernel.yaml is optional so we should not error here if
+	// it is missing
+	if os.IsNotExist(err) {
+	return &Info{}, nil
+	}
	if err != nil {
	return nil, fmt.Errorf("cannot read kernel info: %v", err)
	}
-	return KernelInfoFromKernelYaml(content)
+	return InfoFromKernelYaml(content)
 }
diff --git a/gadget/kernel_test.go b/kernel/kernel_test.go
index f606f0aa61..aef51ee600 100644
--- a/gadget/kernel_test.go
+++ b/kernel/kernel_test.go
@@ -17,22 +17,25 @@
 *
 */
 
-package gadget_test
+package kernel_test
 
 import (
	"io/ioutil"
	"os"
	"path/filepath"
+	"testing"
 
	. "gopkg.in/check.v1"
 
-	"github.com/snapcore/snapd/gadget"
+	"github.com/snapcore/snapd/kernel"
 )
 
 type kernelYamlTestSuite struct{}
 
 var _ = Suite(&kernelYamlTestSuite{})
 
+func TestCommand(t *testing.T) { TestingT(t) }
+
 var mockKernelYaml = []byte(`
 assets:
 dtbs:
@@ -43,17 +46,17 @@ assets:
 `)
 
 func (s *kernelYamlTestSuite) TestInfoFromKernelYamlSad(c *C) {
-	ki, err := gadget.KernelInfoFromKernelYaml([]byte("foo"))
+	ki, err := kernel.InfoFromKernelYaml([]byte("foo"))
	c.Check(err, ErrorMatches, "(?m)cannot parse kernel metadata: .*")
	c.Check(ki, IsNil)
 }
 
 func (s *kernelYamlTestSuite) TestInfoFromKernelYamlHappy(c *C) {
-	ki, err := gadget.KernelInfoFromKernelYaml(mockKernelYaml)
+	ki, err := kernel.InfoFromKernelYaml(mockKernelYaml)
	c.Check(err, IsNil)
-	c.Check(ki, DeepEquals, &gadget.KernelInfo{
-	Assets: map[string]*gadget.KernelAsset{
-	"dtbs": &gadget.KernelAsset{
+	c.Check(ki, DeepEquals, &kernel.Info{
+	Assets: map[string]*kernel.Asset{
+	"dtbs": &kernel.Asset{
	Edition: 1,
	Content: []string{
	"dtbs/bcm2711-rpi-4-b.dtb",
@@ -64,9 +67,22 @@ func (s *kernelYamlTestSuite) TestInfoFromKernelYamlHappy(c *C) {
	})
 }
 
+func (s *kernelYamlTestSuite) TestReadKernelYamlOptional(c *C) {
+	ki, err := kernel.ReadInfo("this-path-does-not-exist")
+	c.Check(err, IsNil)
+	c.Check(ki, DeepEquals, &kernel.Info{})
+}
+
 func (s *kernelYamlTestSuite) TestReadKernelYamlSad(c *C) {
-	ki, err := gadget.ReadKernelInfo("this-path-does-not-exist")
-	c.Check(err, ErrorMatches, `cannot read kernel info: open this-path-does-not-exist/meta/kernel.yaml: no such file or directory`)
+	mockKernelSnapRoot := c.MkDir()
+	kernelYamlPath := filepath.Join(mockKernelSnapRoot, "meta/kernel.yaml")
+	err := os.MkdirAll(filepath.Dir(kernelYamlPath), 0755)
+	c.Assert(err, IsNil)
+	err = ioutil.WriteFile(kernelYamlPath, []byte(`invalid-kernel-yaml`), 0644)
+	c.Assert(err, IsNil)
+
+	ki, err := kernel.ReadInfo(mockKernelSnapRoot)
+	c.Check(err, ErrorMatches, `(?m)cannot parse kernel metadata: yaml: unmarshal errors:.*`)
	c.Check(ki, IsNil)
 }
 
@@ -78,11 +94,11 @@ func (s *kernelYamlTestSuite) TestReadKernelYamlHappy(c *C) {
	err = ioutil.WriteFile(kernelYamlPath, mockKernelYaml, 0644)
	c.Assert(err, IsNil)
 
-	ki, err := gadget.ReadKernelInfo(mockKernelSnapRoot)
+	ki, err := kernel.ReadInfo(mockKernelSnapRoot)
	c.Assert(err, IsNil)
-	c.Check(ki, DeepEquals, &gadget.KernelInfo{
-	Assets: map[string]*gadget.KernelAsset{
-	"dtbs": &gadget.KernelAsset{
+	c.Check(ki, DeepEquals, &kernel.Info{
+	Assets: map[string]*kernel.Asset{
+	"dtbs": &kernel.Asset{
	Edition: 1,
	Content: []string{
	"dtbs/bcm2711-rpi-4-b.dtb",