src/java.base/share/native/libzip/zip_util.c

*** 1204,1214 ****
          if (!addSlash) {
              break;
          }
  
          /* Slash is already there? */
!         if (name[ulen-1] == '/') {
              break;
          }
  
          /* Add slash and try once more */
          name[ulen++] = '/';
--- 1204,1214 ----
          if (!addSlash) {
              break;
          }
  
          /* Slash is already there? */
!         if (ulen > 0 && name[ulen - 1] == '/') {
              break;
          }
  
          /* Add slash and try once more */
          name[ulen++] = '/';