[lxc-devel] [PATCH 1/1] systemd: specify container_ttys in environment

[Stéphane Graber]

On Tue, Jan 27, 2015 at 08:48:25PM +0000, Serge Hallyn wrote:
> The lxc.tty configuration item specifies a number of ttys to create.
> Historically, for each of those, we create a /dev/pts/N entry and
> symlink it to /dev/ttyN for older inits to use.  For systemd, we should
> instead specify each tty name in a $container_ttys environment variable
> passed to init.
> 
> See http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface/ and
> https://github.com/lxc/lxc/issues/419.
> 
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
> ---
>  src/lxc/conf.c  | 43 ++++++++++++++++++++++++++++++++++++++++---
>  src/lxc/conf.h  |  1 +
>  src/lxc/start.c |  8 +++++---
>  3 files changed, 46 insertions(+), 6 deletions(-)
> 
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index c7db06f..da4a928 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -943,9 +943,34 @@ static int setup_dev_symlinks(const struct lxc_rootfs *rootfs)
>  	return 0;
>  }
>  
> -static int setup_tty(const struct lxc_rootfs *rootfs,
> -		     const struct lxc_tty_info *tty_info, char *ttydir)
> +/*
> + * Build a space-separate list of ptys to pass to systemd.
> + */
> +static bool append_ptyname(char **pp, char *name)
>  {
> +	char *p;
> +
> +	if (!*pp) {
> +		*pp = malloc(strlen(name) + strlen("container_ttys=") + 1);
> +		if (!*pp)
> +			return false;
> +		sprintf(*pp, "container_ttys=%s", name);
> +		return true;
> +	}
> +	p = realloc(*pp, strlen(*pp) + strlen(name) + 2);
> +	if (!p)
> +		return false;
> +	*pp = p;
> +	strcat(p, " ");
> +	strcat(p, name);
> +	return true;
> +}
> +
> +static int setup_tty(struct lxc_conf *conf)
> +{
> +	const struct lxc_rootfs *rootfs = &conf->rootfs;
> +	const struct lxc_tty_info *tty_info = &conf->tty_info;
> +	char *ttydir = conf->ttydir;
>  	char path[MAXPATHLEN], lxcpath[MAXPATHLEN];
>  	int i, ret;
>  
> @@ -999,6 +1024,8 @@ static int setup_tty(const struct lxc_rootfs *rootfs,
>  				SYSERROR("failed to create symlink for tty %d", i+1);
>  				return -1;
>  			}
> +			/* Now save the relative path in @path for append_ptyname */
> +			sprintf(path, "%s/tty%d", ttydir, i + 1);
>  		} else {
>  			/* If we populated /dev, then we need to create /dev/ttyN */
>  			if (access(path, F_OK)) {
> @@ -1015,6 +1042,12 @@ static int setup_tty(const struct lxc_rootfs *rootfs,
>  						pty_info->name, path);
>  				continue;
>  			}
> +			/* Now save the relative path in @path for append_ptyname */
> +			sprintf(path, "tty%d", i + 1);
> +		}
> +		if (!append_ptyname(&conf->pty_names, path)) {
> +			ERROR("Error setting up container_ttys string");
> +			return -1;
>  		}
>  	}
>  
> @@ -3794,11 +3827,14 @@ int lxc_setup(struct lxc_handler *handler)
>  			ERROR("failed to setup kmsg for '%s'", name);
>  	}
>  
> -	if (!lxc_conf->is_execute && setup_tty(&lxc_conf->rootfs, &lxc_conf->tty_info, lxc_conf->ttydir)) {
> +	if (!lxc_conf->is_execute && setup_tty(lxc_conf)) {
>  		ERROR("failed to setup the ttys for '%s'", name);
>  		return -1;
>  	}
>  
> +	if (lxc_conf->pty_names && setenv("container_ttys", lxc_conf->pty_names, 1))
> +		SYSERROR("failed to set environment variable for container ptys");
> +
>  	if (!lxc_conf->is_execute && setup_dev_symlinks(&lxc_conf->rootfs)) {
>  		ERROR("failed to setup /dev symlinks for '%s'", name);
>  		return -1;
> @@ -4172,6 +4208,7 @@ void lxc_conf_free(struct lxc_conf *conf)
>  	free(conf->rcfile);
>  	free(conf->init_cmd);
>  	free(conf->unexpanded_config);
> +	free(conf->pty_names);
>  	lxc_clear_config_network(conf);
>  	free(conf->lsm_aa_profile);
>  	free(conf->lsm_se_context);
> diff --git a/src/lxc/conf.h b/src/lxc/conf.h
> index 09065a1..8ec3e8e 100644
> --- a/src/lxc/conf.h
> +++ b/src/lxc/conf.h
> @@ -304,6 +304,7 @@ struct lxc_conf {
>  	struct lxc_list caps;
>  	struct lxc_list keepcaps;
>  	struct lxc_tty_info tty_info;
> +	char *pty_names; // comma-separated list of lxc.tty pty names
>  	struct lxc_console console;
>  	struct lxc_rootfs rootfs;
>  	char *ttydir;
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index 161e4c0..b2c9424 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -745,9 +745,11 @@ static int do_start(void *data)
>  		}
>  	}
>  
> -	if (putenv("container=lxc")) {
> -		SYSERROR("failed to set environment variable 'container=lxc'");
> -		goto out_warn_father;

Why is that being removed?

> +	if (handler->conf->pty_names) {
> +		if (putenv(handler->conf->pty_names)) {
> +			SYSERROR("failed to set environment variable for container ptys");
> +			goto out_warn_father;
> +		}
>  	}
>  
>  	close(handler->sigfd);
> -- 
> 2.1.0
> 
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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