sync/waitgroup: initial sync.WaitGroup wrapper with context support (#319)

Reviewed-on: #319
Co-authored-by: Vasiliy Tolstov <v.tolstov@unistack.org>
Co-committed-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/structfs/metadata_ec2.go

@@ -12,7 +12,7 @@ type EC2Metadata struct {
 			InstanceType       string   `json:"instance-type"`
 			LocalHostname      string   `json:"local-hostname"`
 			LocalIPv4          string   `json:"local-ipv4"`
-			kernelID           int      `json:"kernel-id"`
+			KernelID           int      `json:"kernel-id"`
 			Placement          string   `json:"placement"`
 			AvailabilityZone   string   `json:"availability-zone"`
 			ProductCodes       string   `json:"product-codes"`

util/structfs/structfs.go

@@ -67,9 +67,9 @@ func (fi *fileInfo) Name() string {
 
 func (fi *fileInfo) Mode() os.FileMode {
 	if strings.HasSuffix(fi.name, "/") {
-		return os.FileMode(0755) | os.ModeDir
+		return os.FileMode(0o755) | os.ModeDir
 	}
-	return os.FileMode(0644)
+	return os.FileMode(0o644)
 }
 
 func (fi *fileInfo) IsDir() bool {
@@ -112,15 +112,14 @@ func (f *file) Readdir(count int) ([]os.FileInfo, error) {
 func (f *file) Seek(offset int64, whence int) (int64, error) {
 	//	log.Printf("seek %d %d %s\n", offset, whence, f.name)
 	switch whence {
-	case os.SEEK_SET:
+	case io.SeekStart:
 		f.offset = offset
-	case os.SEEK_CUR:
+	case io.SeekCurrent:
 		f.offset += offset
-	case os.SEEK_END:
+	case io.SeekEnd:
 		f.offset = int64(len(f.data)) + offset
 	}
 	return f.offset, nil
-
 }
 
 func (f *file) Stat() (os.FileInfo, error) {

util/structfs/structfs_test.go

@@ -2,7 +2,7 @@ package structfs
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"reflect"
 	"testing"
@@ -82,7 +82,7 @@ func get(path string) ([]byte, error) {
 		return nil, err
 	}
 	defer res.Body.Close()
-	return ioutil.ReadAll(res.Body)
+	return io.ReadAll(res.Body)
 }
 
 func TestAll(t *testing.T) {