copier.unwrapError(): update for Go 1.16

Since we started calling into the standard library's io/fs package
directly, we effectively made Go 1.16 our minimum Go version, so we
don't need to keep the workaround for compiling with Go 1.12.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

copier/copier.go

@@ -4,6 +4,7 @@ import (
 	"archive/tar"
 	"bytes"
 	"encoding/json"
+	stderrors "errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -1907,3 +1908,15 @@ func copierHandlerRemove(req request) *response {
 	}
 	return &response{Error: "", Remove: removeResponse{}}
 }
+
+func unwrapError(err error) error {
+	e := errors.Cause(err)
+	for e != nil {
+		err = e
+		e = stderrors.Unwrap(err)
+		if e == err {
+			break
+		}
+	}
+	return err
+}

copier/unwrap_112.go

@@ -1,11 +0,0 @@
-// +build !go113
-
-package copier
-
-import (
-	"github.com/pkg/errors"
-)
-
-func unwrapError(err error) error {
-	return errors.Cause(err)
-}

copier/unwrap_113.go

@@ -1,18 +0,0 @@
-// +build go113
-
-package copier
-
-import (
-	stderror "errors"
-
-	"github.com/pkg/errors"
-)
-
-func unwrapError(err error) error {
-	e := errors.Cause(err)
-	for e != nil {
-		err = e
-		e = errors.Unwrap(err)
-	}
-	return err
-}

copier/xattrs.go

@@ -16,7 +16,9 @@ const (
 )
 
 var (
-	relevantAttributes = []string{"security.capability", "security.ima", "user.*"} // the attributes that we preserve - we discard others
+	relevantAttributes    = []string{"security.capability", "security.ima", "user.*"} // the attributes that we preserve - we discard others
+	initialXattrListSize  = 64 * 1024
+	initialXattrValueSize = 64 * 1024
 )
 
 // isRelevantXattr checks if "attribute" matches one of the attribute patterns
@@ -35,7 +37,7 @@ func isRelevantXattr(attribute string) bool {
 // Lgetxattrs returns a map of the relevant extended attributes set on the given file.
 func Lgetxattrs(path string) (map[string]string, error) {
 	maxSize := 64 * 1024 * 1024
-	listSize := 64 * 1024
+	listSize := initialXattrListSize
 	var list []byte
 	for listSize < maxSize {
 		list = make([]byte, listSize)
@@ -61,7 +63,7 @@ func Lgetxattrs(path string) (map[string]string, error) {
 	m := make(map[string]string)
 	for _, attribute := range strings.Split(string(list), string('\000')) {
 		if isRelevantXattr(attribute) {
-			attributeSize := 64 * 1024
+			attributeSize := initialXattrValueSize
 			var attributeValue []byte
 			for attributeSize < maxSize {
 				attributeValue = make([]byte, attributeSize)

copier/xattrs_test.go

@@ -10,6 +10,12 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func init() {
+	// exercise the ERANGE-handling logic
+	initialXattrListSize = 1
+	initialXattrValueSize = 1
+}
+
 func TestXattrs(t *testing.T) {
 	if !xattrsSupported {
 		t.Skipf("xattrs are not supported on this platform, skipping")