Reuse existing user id if it exists

We dont want to fully skip the user update if it exists as it may be for
a specific reason like updating groups and such, but if the entry does
not have a specific user id set by the user object and the user already
exists in the passwd file, we should reuse the userid as to not break
existing files that may have permissions linked to that user

This should fix:
 - users in config files appearing more than once, so their uid wont
   change
 - ssh keys added to users than are updated after the key creation
 - anything else adding a user to the passwd file and bumping the next
   uid free, as our calculation picks the latest free uid

Signed-off-by: Itxaka <[email protected]>

pkg/plugins/user.go

@@ -93,7 +93,6 @@ func createUser(fs vfs.FS, u schema.User, console Console) error {
 			gid = usedGids[len(usedGids)-1]
 			gid++
 		}
-
 	}
 
 	updateGroup := entities.Group{
@@ -112,20 +111,34 @@ func createUser(fs vfs.FS, u schema.User, console Console) error {
 			return errors.Wrap(err, "invalid uid defined")
 		}
 	} else {
-		// find an available uid if there are others already
 		all, _ := passwd.ParseFile(etcpasswd)
 		if len(all) != 0 {
-			usedUids := []int{}
-			for _, entry := range all {
-				uid, _ := strconv.Atoi(entry.Uid)
-				usedUids = append(usedUids, uid)
+			// Check if user is already in there to reuse the same UID as to not break existing permissions
+			existing := false
+			for name, values := range all {
+				if name == u.Name {
+					uid, err = strconv.Atoi(values.Uid)
+					if err != nil {
+						return errors.Wrap(err, "could not parse existing user id")
+					}
+					existing = true
+					break
+				}
 			}
-			sort.Ints(usedUids)
-			if len(usedUids) == 0 {
-				return errors.New("no new UID found")
+			// If it's not there, get a new UID
+			if !existing {
+				usedUids := []int{}
+				for _, entry := range all {
+					uid, _ := strconv.Atoi(entry.Uid)
+					usedUids = append(usedUids, uid)
+				}
+				sort.Ints(usedUids)
+				if len(usedUids) == 0 {
+					return errors.New("no new UID found")
+				}
+				uid = usedUids[len(usedUids)-1]
+				uid++
 			}
-			uid = usedUids[len(usedUids)-1]
-			uid++
 		}
 	}