From mboxrd@z Thu Jan  1 00:00:00 1970
From: arisawa <arisawa@ar.aichi-u.ac.jp>
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Message-Id: <8FB7CBFD-7334-4F9F-8C71-571DEF9FAD31@ar.aichi-u.ac.jp>
Date: Wed, 17 Feb 2016 00:52:37 +0900
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: [9fans] file descriptor leak
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Hello,

I have observed warning messages from dns server:
dns 30792: warning process exceeded 100 file descriptors
dns 30888: warning process exceeded 200 file descriptors
=E2=80=A6

probably the file descriptor leak comes from dnresolve.c

udpquery(Query *qp, char *mntpt, int depth, int patient, int inns)
{
	=E2=80=A6
			msg =3D system(open("/dev/null", ORDWR), =
"outside");
	=E2=80=A6
}

char *
system(int fd, char *cmd)
{
	int pid, p, i;
	static Waitmsg msg;

	if((pid =3D fork()) =3D=3D -1)
		sysfatal("fork failed: %r");
	else if(pid =3D=3D 0){
		dup(fd, 0);
		close(fd);
		for (i =3D 3; i < 200; i++)
			close(i);		/* don't leak fds */
		execl("/bin/rc", "rc", "-c", cmd, nil);
		sysfatal("exec rc: %r");
	}
	for(p =3D waitpid(); p >=3D 0; p =3D waitpid())
		if(p =3D=3D pid)
			return msg.msg;
	return "lost child";
}

fd is lost if pid > 0

my server is running on 9front. however both 9atom and bell-labs use =
same routine.

Kenji Arisawa