libvirt users - May 2012 - lxc: Add /dev/tty to lxcContainerPopulateDevices() ?

Hi,

src/lxc/lxc_container.c:lxcContainerPopulateDevices() has this table
of devices that are automatically created when an lxc container is
started.

    const struct {
        int maj;
        int min;
        mode_t mode;
        const char *path;
    } devs[] = {
        { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_NULL, 0666, "/dev/null" },
        { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_ZERO, 0666, "/dev/zero" },
        { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_FULL, 0666, "/dev/full" },
        { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_RANDOM, 0666, "/dev/random"
},
        { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_URANDOM, 0666,
"/dev/urandom" },
    };

Can we add '/dev/tty' to this list ?

We were trying to run 'smbpasswd -a user' inside a container without
/dev/tty and the fopen("/dev/tty", "w+") in smbpasswd made
/dev/tty
a regular file, breaking man(1), less(1), and ofcourse smbpasswd :-)

Sure we can add /dev/tty to container's rc.local or something, but
wouldn't it be in the same category as say, /dev/null or /dev/zero ?

Sukadev

On Wed, May 16, 2012 at 03:44:19PM -0700, Sukadev Bhattiprolu
wrote:
> Hi,
> 
> src/lxc/lxc_container.c:lxcContainerPopulateDevices() has this table
> of devices that are automatically created when an lxc container is
> started.
> 
>     const struct {
>         int maj;
>         int min;
>         mode_t mode;
>         const char *path;
>     } devs[] = {
>         { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_NULL, 0666, "/dev/null"
},
>         { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_ZERO, 0666, "/dev/zero"
},
>         { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_FULL, 0666, "/dev/full"
},
>         { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_RANDOM, 0666,
"/dev/random" },
>         { LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_URANDOM, 0666,
"/dev/urandom" },
>     };
> 
> Can we add '/dev/tty' to this list ?
> 
> We were trying to run 'smbpasswd -a user' inside a container
without
> /dev/tty and the fopen("/dev/tty", "w+") in smbpasswd
made /dev/tty
> a regular file, breaking man(1), less(1), and ofcourse smbpasswd :-)
> 
> Sure we can add /dev/tty to container's rc.local or something, but
> wouldn't it be in the same category as say, /dev/null or /dev/zero ?
No, we can't just pass in the host's /dev/tty device to the
container. We need to virtualize it, but this is not really
very easy todo if we need to take account of multiple consoles.
Probably as a temporar hack, we can just symlink it to /dev/tty1
and try to figure out a proper fix later

Daniel
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