Merge pull request #4 from kairos-io/create-info-file-if-not-exists

Create the partition file if it doesn't exist

pkg/partition_info/partition_info.go

@@ -3,6 +3,7 @@ package partition_info
 import (
 	"fmt"
 	"io/ioutil"
+	"os"
 	"strings"
 
 	"github.com/jaypipes/ghw/pkg/block"
@@ -22,16 +23,27 @@ type PartitionInfo struct {
 	mapping map[string]string
 }
 
-func NewPartitionInfoFromFile(file string) (*PartitionInfo, error) {
+// NewPartitionInfoFromFile reads the given partition info file (if one exists)
+// and returns a pointer to a PartitionInfo object.
+// If a file doesn't exist, the function will create one and return an "empty"
+// PartitionInfo object.
+// The boolean return value indicates whether a file existed or not (true means,
+// a file existed already).
+func NewPartitionInfoFromFile(file string) (*PartitionInfo, bool, error) {
+	existed, err := createInfoFileIfNotExists(file)
+	if err != nil {
+		return nil, existed, err
+	}
+
 	mapping, err := ParsePartitionInfoFile(file)
 	if err != nil {
-		return nil, err
+		return nil, existed, err
 	}
 
 	return &PartitionInfo{
 		file:    file,
 		mapping: mapping,
-	}, nil
+	}, existed, nil
 }
 
 func (pi PartitionInfo) LookupUUIDForLabel(l string) string {
@@ -98,3 +110,16 @@ func ParsePartitionInfoFile(file string) (map[string]string, error) {
 
 	return result, nil
 }
+
+// createInfoFileIfNotExists returns true if file already exists or creates the
+// the file if it doesn't exist and returns false.
+func createInfoFileIfNotExists(fileName string) (bool, error) {
+	_, err := os.Stat(fileName)
+	if errors.Is(err, os.ErrNotExist) {
+		if _, err := os.Create(fileName); err != nil {
+			return false, err
+		}
+		return false, nil
+	}
+	return true, nil
+}

pkg/partition_info/partition_info_test.go

@@ -1,8 +1,11 @@
 package partition_info_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
+	"path"
+	"time"
 
 	"github.com/jaypipes/ghw/pkg/block"
 	. "github.com/onsi/ginkgo/v2"
@@ -18,11 +21,31 @@ var _ = Describe("Partition Info file parsing", func() {
 		BeforeEach(func() {
 			file = "../../tests/assets/partition_info.yaml"
 		})
+		When("the files exists already", func() {
+			It("returns 'true' and a PartitionInfo object", func() {
+				result, existed, err := pi.NewPartitionInfoFromFile(file)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(result).ToNot(BeNil())
+				Expect(existed).To(BeTrue())
+			})
+		})
 
-		It("returns a PartitionInfo", func() {
-			result, err := pi.NewPartitionInfoFromFile(file)
-			Expect(err).ToNot(HaveOccurred())
-			Expect(result).ToNot(BeNil())
+		When("a file doesn't exist", func() {
+			var fileName string
+			BeforeEach(func() {
+				fileName = path.Join(
+					os.TempDir(),
+					fmt.Sprintf("partition-info-%d.yaml", time.Now().UnixNano()))
+			})
+
+			It("creates the file and returns 'false' and an (empty) mapping", func() {
+				result, existed, err := pi.NewPartitionInfoFromFile(fileName)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(result).ToNot(BeNil())
+				Expect(existed).To(BeFalse())
+				_, err = os.Stat(fileName)
+				Expect(err).ToNot(HaveOccurred())
+			})
 		})
 	})
 
@@ -86,7 +109,7 @@ var _ = Describe("Partition Info file parsing", func() {
 			_, err = file.Write([]byte("TO_KEEP: old_uuid_1"))
 			Expect(err).ToNot(HaveOccurred())
 
-			partitionInfo, err = pi.NewPartitionInfoFromFile(file.Name())
+			partitionInfo, _, err = pi.NewPartitionInfoFromFile(file.Name())
 			Expect(err).ToNot(HaveOccurred())
 		})
 
@@ -117,7 +140,7 @@ TO_KEEP: old_uuid_1
 
 		BeforeEach(func() {
 			file = "../../tests/assets/partition_info.yaml"
-			partitionInfo, err = pi.NewPartitionInfoFromFile(file)
+			partitionInfo, _, err = pi.NewPartitionInfoFromFile(file)
 			Expect(err).ToNot(HaveOccurred())
 		})
 
@@ -139,7 +162,7 @@ TO_KEEP: old_uuid_1
 
 		BeforeEach(func() {
 			file = "../../tests/assets/partition_info.yaml"
-			partitionInfo, err = pi.NewPartitionInfoFromFile(file)
+			partitionInfo, _, err = pi.NewPartitionInfoFromFile(file)
 			Expect(err).ToNot(HaveOccurred())
 		})