使用C（Carbon，标准C / C ++）将文件标记为OSX上的可执行文件

I'm looking for a way to programatically set the 'executable' bit on a file on OS X. I don't want to invoke 'chmod a+x' but I want the same effect as the chmod call. Any suggestions? A carbon API or any other C/C++ function would work...I'm looking for a way to programatically set th