Re: [Libguestfs] [PATCH nbdkit] sh: Remove assert and replace with smarter file descriptor duplication. (was: Re: [nbdkit PATCH v2 14/17] sh: Use pipe2 with CLOEXEC when possible)

On Tue, Aug 27, 2019 at 08:31:26AM -0500, Eric Blake wrote: I had a play around with implementing that, but I'm not sure that it would be the right thing to do. We still have the problem of how to deal with nbdkit being run with fd=0, 1 or 2 being closed, which will still cause this assertion to be thrown elsewhere: $ perl -e 'close STDIN; close STDOUT; system ("nbdkit -fv sh /tmp/min.sh")' nbdkit: debug: TLS disabled: could not load TLS certificates nbdkit: debug: registering plugin /usr/lib64/nbdkit/plugins/nbdkit-sh-plugin.so nbdkit: debug: registered plugin /usr/lib64/nbdkit/plugins/nbdkit-sh-plugin.so (name sh) nbdkit: debug: sh: load nbdkit: debug: sh: load: tmpdir: /tmp/nbdkitshWLQqWC nbdkit: debug: sh: config key=script, value=/tmp/min.sh nbdkit: debug: /tmp/min.sh: invoking load ... nbdkit: call.c:155: call3: Assertion `in_fd[0] > STDERR_FILENO && in_fd[1] > STDERR_FILENO && out_fd[0] > STDERR_FILENO && out_fd[1] > STDERR_FILENO && err_fd[0] > STDERR_FILENO && err_fd[1] > STDERR_FILENO' failed. While it's obviously a bug in the caller to run nbdkit like this, I think we should consider making nbdkit a bit more robust to it as an appeal of nbdkit is that it can be used in embedded-style situations. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top