Use time.Time not string for LastModified

Signed-off-by: Anders F Björklund <anders.f.bjorklund@gmail.com>

pkg/downloader/downloader.go

@@ -13,12 +13,14 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/cheggaaa/pb/v3"
 	"github.com/containerd/continuity/fs"
 	"github.com/lima-vm/lima/pkg/httpclientutil"
 	"github.com/lima-vm/lima/pkg/localpathutil"
 	"github.com/lima-vm/lima/pkg/progressbar"
+	"github.com/lima-vm/lima/pkg/timeutil"
 	"github.com/opencontainers/go-digest"
 	"github.com/sirupsen/logrus"
 )
@@ -44,7 +46,7 @@ const (
 type Result struct {
 	Status          Status
 	CachePath       string // "/Users/foo/Library/Caches/lima/download/by-url-sha256/<SHA256_OF_URL>/data"
-	LastModified    string
+	LastModified    time.Time
 	ContentType     string
 	ValidatedDigest bool
 }
@@ -131,6 +133,17 @@ func readFile(path string) string {
 	return string(b)
 }
 
+func readTime(path string) time.Time {
+	if _, err := os.Stat(path); err != nil {
+		return time.Time{}
+	}
+	t, err := timeutil.ReadTime(path)
+	if err != nil {
+		return time.Time{}
+	}
+	return t
+}
+
 // Download downloads the remote resource into the local path.
 //
 // Download caches the remote resource if WithCache or WithCacheDir option is specified.
@@ -225,7 +238,7 @@ func Download(ctx context.Context, local, remote string, opts ...Opt) (*Result,
 		res := &Result{
 			Status:          StatusUsedCache,
 			CachePath:       shadData,
-			LastModified:    readFile(shadTime),
+			LastModified:    readTime(shadTime),
 			ContentType:     readFile(shadType),
 			ValidatedDigest: o.expectedDigest != "",
 		}
@@ -256,7 +269,7 @@ func Download(ctx context.Context, local, remote string, opts ...Opt) (*Result,
 	res := &Result{
 		Status:          StatusDownloaded,
 		CachePath:       shadData,
-		LastModified:    readFile(shadTime),
+		LastModified:    readTime(shadTime),
 		ContentType:     readFile(shadType),
 		ValidatedDigest: o.expectedDigest != "",
 	}
@@ -306,7 +319,7 @@ func Cached(remote string, opts ...Opt) (*Result, error) {
 	res := &Result{
 		Status:          StatusUsedCache,
 		CachePath:       shadData,
-		LastModified:    readFile(shadTime),
+		LastModified:    readTime(shadTime),
 		ContentType:     readFile(shadType),
 		ValidatedDigest: o.expectedDigest != "",
 	}

pkg/timeutil/timeutil.go

@@ -0,0 +1,22 @@
+package timeutil
+
+import (
+	"os"
+	"time"
+)
+
+// same format as HTTP headers
+const timeFormat = time.RFC1123
+
+func ReadTime(name string) (time.Time, error) {
+	data, err := os.ReadFile(name)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Parse(timeFormat, string(data))
+}
+
+func WriteTime(name string, tm time.Time, perm os.FileMode) error {
+	data := tm.Format(timeFormat)
+	return os.WriteFile(name, []byte(data), perm)
+}

pkg/timeutil/timeutil_test.go

@@ -0,0 +1,33 @@
+package timeutil
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"gotest.tools/v3/assert"
+)
+
+var testTime time.Time
+var testData = testTime.Format(timeFormat)
+
+func TestReadTime(t *testing.T) {
+	tmpFile := filepath.Join(t.TempDir(), "time")
+	err := os.WriteFile(tmpFile, []byte(testData), 0o644)
+	assert.NilError(t, err)
+
+	tm, err := ReadTime(tmpFile)
+	assert.NilError(t, err)
+	assert.Equal(t, tm, testTime)
+}
+
+func TestWriteTime(t *testing.T) {
+	tmpFile := filepath.Join(t.TempDir(), "time")
+	err := WriteTime(tmpFile, testTime, 0o644)
+	assert.NilError(t, err)
+
+	b, err := os.ReadFile(tmpFile)
+	assert.NilError(t, err)
+	assert.Equal(t, string(b), testData)
+}