pkg: add 'sbom' package for working with SBOM documents

Add a new `sbom` package for working with SBOM documents. It provides a
very simple wrapper struct, which currently supports only SPDX standard.
The SBOM document is for now stored in a raw JSON form, to not have to
convert the raw data from and to the specific in-memory representation
on the worker.

The idea is to provide a bit of an abstraction from the specific SBOM
implementation, so that in the future, it would be possible to create
`sbom.Document` from SBOM documents of various standards and also
serialize it back to various SBOM standards.

Signed-off-by: Tomáš Hozza <[email protected]>

pkg/sbom/document.go

@@ -0,0 +1,70 @@
+package sbom
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type StandardType uint64
+
+const (
+	StandardTypeNone StandardType = iota
+	StandardTypeSpdx
+)
+
+func (t StandardType) String() string {
+	switch t {
+	case StandardTypeNone:
+		return "none"
+	case StandardTypeSpdx:
+		return "spdx"
+	default:
+		panic("invalid standard type")
+	}
+}
+
+func (t StandardType) MarshalJSON() ([]byte, error) {
+	var s string
+
+	if t == StandardTypeNone {
+		s = ""
+	} else {
+		s = t.String()
+	}
+
+	return json.Marshal(s)
+}
+
+func (t *StandardType) UnmarshalJSON(data []byte) error {
+	switch string(data) {
+	case `""`:
+		*t = StandardTypeNone
+	case `"spdx"`:
+		*t = StandardTypeSpdx
+	default:
+		return fmt.Errorf("invalid SBOM standard type: %s", data)
+	}
+	return nil
+}
+
+type Document struct {
+	// type of the document standard
+	DocType StandardType
+
+	// document in a specific standard JSON raw format
+	Document json.RawMessage
+}
+
+func NewDocument(docType StandardType, doc json.RawMessage) (*Document, error) {
+	switch docType {
+	case StandardTypeSpdx:
+		docType = StandardTypeSpdx
+	default:
+		return nil, fmt.Errorf("unsupported SBOM document type: %s", docType)
+	}
+
+	return &Document{
+		DocType:  docType,
+		Document: doc,
+	}, nil
+}

pkg/sbom/document_test.go

@@ -0,0 +1,86 @@
+package sbom
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStandardTypeJSONUnmarhsall(t *testing.T) {
+	type testStruct struct {
+		Type     StandardType `json:"type"`
+		TypeOmit StandardType `json:"type_omit,omitempty"`
+	}
+
+	tests := []struct {
+		name string
+		data []byte
+		want testStruct
+	}{
+		{
+			name: "StandardTypeNone",
+			data: []byte(`{"type":""}`),
+			want: testStruct{
+				Type:     StandardTypeNone,
+				TypeOmit: StandardTypeNone,
+			},
+		},
+		{
+			name: "StandardTypeSpdx",
+			data: []byte(`{"type":"spdx","type_omit":"spdx"}`),
+			want: testStruct{
+				Type:     StandardTypeSpdx,
+				TypeOmit: StandardTypeSpdx,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var ts testStruct
+			err := json.Unmarshal(tt.data, &ts)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, ts)
+		})
+	}
+}
+
+func TestStandardTypeJSONMarhsall(t *testing.T) {
+	type TestStruct struct {
+		Type     StandardType `json:"type"`
+		TypeOmit StandardType `json:"type_omit,omitempty"`
+	}
+
+	tests := []struct {
+		name string
+		want []byte
+		data TestStruct
+	}{
+		{
+			name: "StandardTypeNone",
+			want: []byte(`{"type":""}`),
+			data: TestStruct{
+				Type:     StandardTypeNone,
+				TypeOmit: StandardTypeNone,
+			},
+		},
+		{
+			name: "StandardTypeSpdx",
+			want: []byte(`{"type":"spdx","type_omit":"spdx"}`),
+			data: TestStruct{
+				Type:     StandardTypeSpdx,
+				TypeOmit: StandardTypeSpdx,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got []byte
+			got, err := json.Marshal(tt.data)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}