fix invalid read when trimming empty string

tony2001 · tony2001 · commit bb60122c2fe4 · 2012-11-11T22:37:04.000+04:00
diff --git a/ext/filter/filter_private.h b/ext/filter/filter_private.h
@@ -107,8 +107,10 @@
 	if (len < 1) { \
 		RETURN_VALIDATION_FAILED \
 	} \
-	while (p[len-1] == ' ' || p[len-1] == '\t' || p[len-1] == '\r' || p[len-1] == '\v' || p[len-1] == '\n') { \
-		len--; \
+	if (len > 0) { \
+		while (p[len-1] == ' ' || p[len-1] == '\t' || p[len-1] == '\r' || p[len-1] == '\v' || p[len-1] == '\n') { \
+			len--; \
+		} \
 	} \
 }
 
