service: Avoid underflow in logs padding calculation

This command inserts a variable amount of padding in the log line: padding := strings.Repeat(" ", f.padding-getMaxLength(task.Slot)) If the service is scaled up, or the slot numbers are noncontiguous, the subtraction can underflow, causing a crash. Signed-off-by: Aaron Lehmann <[email protected]>
clnperez · May 16, 2017 · ab6bc5d · ab6bc5d
1 parent a222527
commit ab6bc5d
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/cli/command/service/logs.go b/cli/command/service/logs.go
@@ -204,8 +204,12 @@ func (f *taskFormatter) format(ctx context.Context, logCtx logContext) (string,
 		}
 	}
 
-	padding := strings.Repeat(" ", f.padding-getMaxLength(task.Slot))
-	formatted := fmt.Sprintf("%s@%s%s", taskName, nodeName, padding)
+	paddingCount := f.padding - getMaxLength(task.Slot)
+	padding := ""
+	if paddingCount > 0 {
+		padding = strings.Repeat(" ", paddingCount)
+	}
+	formatted := taskName + "@" + nodeName + padding
 	f.cache[logCtx] = formatted
 	return formatted, nil
 }