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659

answers:

1
+4  Q: 

how to set close-on-exec by default

I'm implementing a library to run commands. The library is C, on Linux.

It currently does a popen() call to run a command and get output. The problem is that the command inherits all currently open file handlers.

If I did a fork/exec I could close the handlers in child explicitly. But that means re-implementing popen().

Can I set close-on-exec on all handlers without looping through them one by one?

Can I set close-on-exec as default for the process?

Thanks!

+2  A: 
ephemient  2009-10-29 15:35:46
being a library, I don't control how my users open files, so using flags in open() is not an option
n-alexander  2009-10-30 15:18:16
Too bad, you're out of luck -- UNIX (and Linux) will not let you change the underlying semantics of `open` et al. You'll just have to live with it, like everybody else.
ephemient  2009-10-30 19:44:06
See http://lkml.org/lkml/2004/3/29/191 for an example of a cloexec-by-default-switch proposal being shot down. This has been proposed many times and been declined just as many times.
ephemient  2009-10-30 19:48:03
just backward compatibility again. Too badI've seen lots of cases when inherited files got stuck because a loose child didn't exit, and since it's loose there isn't much you can do about it. Not even kill easily. Is manual fork/exec with close really the only way to build something reliable?
n-alexander  2009-11-02 11:14:43

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