[lxc-devel] [PATCH] don't set up console for lxc-execute

[Dwight Engen]

On Thu, 13 Jun 2013 10:09:59 -0500
Serge Hallyn <serge.hallyn at ubuntu.com> wrote:

> Currently due to some safety checks for !rootfs.path, lxc-execute
> works ok if you do not set lxc.rootfs at all in your lxc.conf. But if
> you set lxc.rootfs = '/', then it sets up console, and when you do an
> lxc-execute, the console appears hung.
> 
> However the lxc.rootfs NULL check was just incidental to not
> dereference a NULL pointer.  In fact we should not be setting up a
> console if the container isn't running a full-fledged distro with a
> getty/login running on the container's /dev/console.
> 
> Have lxc_execute() mark in lxc_conf that this is a lxc-execute and not
> an lxc-start, and don't set up the console.
> 
> The issue is documented at https://sourceforge.net/p/lxc/bugs/67/ .
> 
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>

Acked-by: Dwight Engen <dwight.engen at oracle.com>

> ---
>  src/lxc/conf.c    |  4 ++--
>  src/lxc/conf.h    |  1 +
>  src/lxc/console.c | 10 ++++++++++
>  src/lxc/execute.c |  1 +
>  4 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index a4ed218..d3dc9a5 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -2836,7 +2836,7 @@ int lxc_setup(const char *name, struct lxc_conf
> *lxc_conf) }
>  	}
>  
> -	if (setup_console(&lxc_conf->rootfs, &lxc_conf->console,
> lxc_conf->ttydir)) {
> +	if (!lxc_conf->is_execute &&
> setup_console(&lxc_conf->rootfs, &lxc_conf->console,
> lxc_conf->ttydir)) { ERROR("failed to setup the console for '%s'",
> name); return -1; }
> @@ -2846,7 +2846,7 @@ int lxc_setup(const char *name, struct lxc_conf
> *lxc_conf) ERROR("failed to setup kmsg for '%s'", name);
>  	}
>  
> -	if (setup_tty(&lxc_conf->rootfs, &lxc_conf->tty_info,
> lxc_conf->ttydir)) {
> +	if (!lxc_conf->is_execute && setup_tty(&lxc_conf->rootfs,
> &lxc_conf->tty_info, lxc_conf->ttydir)) { ERROR("failed to setup the
> ttys for '%s'", name); return -1;
>  	}
> diff --git a/src/lxc/conf.h b/src/lxc/conf.h
> index 2fd3ab1..9b1677e 100644
> --- a/src/lxc/conf.h
> +++ b/src/lxc/conf.h
> @@ -251,6 +251,7 @@ struct saved_nic {
>  };
>  
>  struct lxc_conf {
> +	int is_execute;
>  	char *fstab;
>  	int tty;
>  	int pts;
> diff --git a/src/lxc/console.c b/src/lxc/console.c
> index f801e0b..125890f 100644
> --- a/src/lxc/console.c
> +++ b/src/lxc/console.c
> @@ -276,6 +276,11 @@ int lxc_console_mainloop_add(struct
> lxc_epoll_descr *descr, struct lxc_conf *conf = handler->conf;
>  	struct lxc_console *console = &conf->console;
>  
> +	if (conf->is_execute) {
> +		INFO("no console for lxc-execute.");
> +		return 0;
> +	}
> +
>  	if (!conf->rootfs.path) {
>  		INFO("no rootfs, no console.");
>  		return 0;
> @@ -564,6 +569,11 @@ int lxc_console_create(struct lxc_conf *conf)
>  {
>  	struct lxc_console *console = &conf->console;
>  
> +	if (conf->is_execute) {
> +		INFO("no console for lxc-execute.");
> +		return 0;
> +	}
> +
>  	if (!conf->rootfs.path)
>  		return 0;
>  
> diff --git a/src/lxc/execute.c b/src/lxc/execute.c
> index 9bf33ca..3cf3540 100644
> --- a/src/lxc/execute.c
> +++ b/src/lxc/execute.c
> @@ -158,5 +158,6 @@ int lxc_execute(const char *name, char *const
> argv[], int quiet, if (lxc_check_inherited(conf, -1))
>  		return -1;
>  
> +	conf->is_execute = 1;
>  	return __lxc_start(name, conf, &execute_start_ops, &args,
> lxcpath); }