Re: PATCH: 3.0.6/3.1.6: Re: All sorts of file-descriptor strangeness

["Bart Schaefer" <schaefer@candle.brasslantern.com>]

On Oct 10,  6:53pm, Zefram wrote:
} Subject: Re: PATCH: Re: PATCH: no more fd mixups
}
} Bart Schaefer wrote:
} >Here's a tweak to Zefram's patch to [...] test
} >that the descriptor is in the fdtable[] array,
} 
} At the moment, coprocess fds do not get passed on to children, but they
} are explicitly marked as public in fdtable[], and hence after your patch
} they are dupable by number.

Yes, that's true.  While we're on the topic:

zagzig[21] coproc tr a-z A-Z
[1] 2510
zagzig[22] exec 5<&p
zagzig[23] ls -l /proc/self/fd
total 0
lrwx------   1 schaefer schaefer       64 Oct 10 13:48 0 -> [0301]:11232
lrwx------   1 schaefer schaefer       64 Oct 10 13:48 1 -> [0301]:11232
lrwx------   1 schaefer schaefer       64 Oct 10 13:48 2 -> [0301]:11232
lr-x------   1 schaefer schaefer       64 Oct 10 13:48 3 -> [0001]:164691976
lr-x------   1 schaefer schaefer       64 Oct 10 13:48 5 -> [0000]:12364629

Should descriptor 5 have been passed on to "ls" in this manner?  (Note
that /proc/self/fd are the fds of "ls" at that point, not of the shell.)

} I *think* all that needs to change is to remove the line
} 
} 	fdtable[coprocin] = fdtable[coprocout] = 0;

I'm concerned about that because there are other places where the fds with
nonzero entries in fdtable[] are either closed, or deliberately kept open,
in circumstances that may not apply to the coproc.  In particular, I think
it would break this:

    coproc foo
    bar <(baz <&p)
 
Probably it's better to just extend the test we've already tweaked twice
now, so that it explicitly tests the coproc fds as well.

Index: exec.c
===================================================================
@@ -1671,7 +1671,10 @@
 	    case MERGEOUT:
 		if (fn->fd2 < 10)
 		    closemn(mfds, fn->fd2);
-		if (fn->fd2 > 9 && fdtable[fn->fd2]) {
+		if (fn->fd2 > 9 &&
+		    (fdtable[fn->fd2] ||
+		     fn->fd2 == coprocin ||
+		     fn->fd2 == coprocout)) {
 		    fil = -1;
 		    errno = EBADF;
 		} else {

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com