compare: correctly use .Prefix() during comparisons

During the rework of how xattr fields are handled, the comparison code
was not correctly updated. As a result, changes to xattrs would not be
detected in any form. This was detected in the umoci integration suite.
In addition, fix the dh.UsedKeywords logic so auto-detection works
correctly with prefix-based xattrs.

Fixes: ed464af ("*: xattr can Update()")
Signed-off-by: Aleksa Sarai <[email protected]>

Author: cyphar

compare.go

@@ -197,7 +197,7 @@ func compareEntry(oldEntry, newEntry Entry) ([]KeyDelta, error) {
 	for _, kv := range oldKeys {
 		key := kv.Keyword()
 		// only add this diff if the new keys has this keyword
-		if key != "tar_time" && key != "time" && key != "xattr" && len(HasKeyword(newKeys, key)) == 0 {
+		if key != "tar_time" && key != "time" && key.Prefix() != "xattr" && len(HasKeyword(newKeys, key)) == 0 {
 			continue
 		}
 
@@ -216,7 +216,7 @@ func compareEntry(oldEntry, newEntry Entry) ([]KeyDelta, error) {
 	for _, kv := range newKeys {
 		key := kv.Keyword()
 		// only add this diff if the old keys has this keyword
-		if key != "tar_time" && key != "time" && key != "xattr" && len(HasKeyword(oldKeys, key)) == 0 {
+		if key != "tar_time" && key != "time" && key.Prefix() != "xattr" && len(HasKeyword(oldKeys, key)) == 0 {
 			continue
 		}
 
@@ -414,7 +414,7 @@ func Compare(oldDh, newDh *DirectoryHierarchy, keys []Keyword) ([]InodeDelta, er
 			if keys != nil {
 				var filterChanged []KeyDelta
 				for _, keyDiff := range changed {
-					if InKeywordSlice(keyDiff.name, keys) {
+					if InKeywordSlice(keyDiff.name.Prefix(), keys) {
 						filterChanged = append(filterChanged, keyDiff)
 					}
 				}

hierarchy.go

@@ -36,7 +36,7 @@ func (dh DirectoryHierarchy) UsedKeywords() []Keyword {
 			if e.Type != SpecialType || e.Name == "/set" {
 				kvs := e.Keywords
 				for _, kv := range kvs {
-					kw := KeyVal(kv).Keyword()
+					kw := KeyVal(kv).Keyword().Prefix()
 					if !InKeywordSlice(kw, usedkeywords) {
 						usedkeywords = append(usedkeywords, KeywordSynonym(string(kw)))
 					}

hierarchy_test.go

@@ -20,6 +20,19 @@ var checklist = []struct {
   .COMMIT_EDITMSG.un~ size=1006 mode=0644 time=1479325423.450468662 sha1digest=dead0face
   .TAG_EDITMSG.un~ size=1069 mode=0600 time=1471362316.801317529 sha256digest=dead0face
 `, set: []Keyword{"size", "mode", "time", "sha256digest"}},
+	{blob: `
+#          user: cyphar
+#       machine: ryuk
+#          tree: xattr
+#          date: Fri Sep 29 21:00:41 2017
+#      keywords: size,type,uid,gid,mode,link,nlink,time,xattr
+
+# .
+/set type=file nlink=1 mode=0664 uid=1000 gid=100 xattr.user.kira=SSdsbCB0YWtlIGEgcG90YXRvIGNoaXAuLi4gYW5kIGVhdCBpdCE=
+. size=8 type=dir mode=0755 time=1506666472.255992830
+    file size=0 mode=0644 time=1506666472.255992830 xattr.user.something=dGVzdA==
+..
+`, set: []Keyword{"size", "type", "uid", "gid", "mode", "nlink", "time", "xattr"}},
 }
 
 func TestUsedKeywords(t *testing.T) {