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. 

2 files changed, 177 insertions, 0 deletions

diff --git a/kernel/kernel.go b/kernel/kernel.go
new file mode 100644
index 0000000000..0a9a9f95f5
--- /dev/null
+++ b/kernel/kernel.go
@@ -0,0 +1,67 @@
+// -*- 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 kernel
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"gopkg.in/yaml.v2"
+
+	"github.com/snapcore/snapd/gadget/edition"
+)
+
+type Asset struct {
+	Edition edition.Number `yaml:"edition,omitempty"`
+	Content []string `yaml:"content,omitempty"`
+}
+
+type Info struct {
+	Assets map[string]*Asset `yaml:"assets,omitempty"`
+}
+
+// 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)
+	}
+
+	return &ki, nil
+}
+
+// ReadInfo reads the kernel specific metadata from meta/kernel.yaml
+// in the snap root directory.
+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 InfoFromKernelYaml(content)
+}
diff --git a/kernel/kernel_test.go b/kernel/kernel_test.go
new file mode 100644
index 0000000000..aef51ee600
--- /dev/null
+++ b/kernel/kernel_test.go
@@ -0,0 +1,110 @@
+// -*- 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 kernel_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	. "gopkg.in/check.v1"
+
+	"github.com/snapcore/snapd/kernel"
+)
+
+type kernelYamlTestSuite struct{}
+
+var _ = Suite(&kernelYamlTestSuite{})
+
+func TestCommand(t *testing.T) { TestingT(t) }
+
+var mockKernelYaml = []byte(`
+assets:
+ dtbs:
+ edition: 1
+ content:
+ - dtbs/bcm2711-rpi-4-b.dtb
+ - dtbs/bcm2836-rpi-2-b.dtb
+`)
+
+func (s *kernelYamlTestSuite) TestInfoFromKernelYamlSad(c *C) {
+	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 := kernel.InfoFromKernelYaml(mockKernelYaml)
+	c.Check(err, IsNil)
+	c.Check(ki, DeepEquals, &kernel.Info{
+	Assets: map[string]*kernel.Asset{
+	"dtbs": &kernel.Asset{
+	Edition: 1,
+	Content: []string{
+	"dtbs/bcm2711-rpi-4-b.dtb",
+	"dtbs/bcm2836-rpi-2-b.dtb",
+	},
+	},
+	},
+	})
+}
+
+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) {
+	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)
+}
+
+func (s *kernelYamlTestSuite) TestReadKernelYamlHappy(c *C) {
+	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, mockKernelYaml, 0644)
+	c.Assert(err, IsNil)
+
+	ki, err := kernel.ReadInfo(mockKernelSnapRoot)
+	c.Assert(err, IsNil)
+	c.Check(ki, DeepEquals, &kernel.Info{
+	Assets: map[string]*kernel.Asset{
+	"dtbs": &kernel.Asset{
+	Edition: 1,
+	Content: []string{
+	"dtbs/bcm2711-rpi-4-b.dtb",
+	"dtbs/bcm2836-rpi-2-b.dtb",
+	},
+	},
+	},
+	})
+}