[lxc-devel] [PATCH 2/3] execute: bind init.lxc.static into container

[Stéphane Graber]

On Mon, May 12, 2014 at 06:04:00PM +0000, Serge Hallyn wrote:
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>

So one concern here is that SBINDIR may be pretty much anything and may
look pretty awkward in the container, can we have the bind-mount be done
with say /lxc.init.static instead and only be done in the last resort
case where an existing init couldn't be found?

> ---
>  src/lxc/conf.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index 7427a94..0580f46 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -3811,6 +3811,61 @@ static void remount_all_slave(void)
>  		free(line);
>  }
>  
> +void lxc_execute_bind_init(struct lxc_conf *conf)
> +{
> +	int ret;
> +	char path[PATH_MAX], destpath[PATH_MAX];
> +
> +	ret = snprintf(path, PATH_MAX, SBINDIR "/init.lxc.static");
> +	if (ret < 0 || ret >= PATH_MAX) {
> +		WARN("Path name too long searching for lxc.init.static");
> +		return;
> +	}
> +
> +	if (!file_exists(path)) {
> +		INFO("%s does not exist on host", path);
> +		return;
> +	}
> +
> +	ret = snprintf(destpath, PATH_MAX, "%s%s", conf->rootfs.mount, path);
> +	if (ret < 0 || ret >= PATH_MAX) {
> +		WARN("Path name too long for container's lxc.init.static");
> +		return;
> +	}
> +
> +	if (!file_exists(destpath)) {
> +		FILE *pathfile;
> +		char *pathdirname = strdup(path);
> +
> +		if (!pathdirname) {
> +			SYSERROR("Out of memory binding lxc.init.static into container");
> +			return;
> +		}
> +		pathdirname = dirname(pathdirname);
> +		ret = mkdir_p(pathdirname, 0755);
> +		free(pathdirname);
> +		if (ret < 0) {
> +			/*
> +			 * this can fail just due to read-only bind mounts.  Trust
> +			 * that the user knows what they want, log and proceed
> +			 */
> +			WARN("Failed to create %s in container", SBINDIR);
> +			return;
> +		}
> +		pathfile = fopen(destpath, "wb");
> +		if (!pathfile) {
> +			SYSERROR("Failed to create mount target '%s'", destpath);
> +			return;
> +		}
> +		fclose(pathfile);
> +	}
> +
> +	ret = mount(path, destpath, "none", MS_BIND, NULL);
> +	if (ret < 0)
> +		SYSERROR("Failed to bind lxc.init.static into container");
> +	INFO("lxc.init.static bound into container at %s", path);
> +}
> +
>  int lxc_setup(struct lxc_handler *handler)
>  {
>  	const char *name = handler->name;
> @@ -3878,6 +3933,9 @@ int lxc_setup(struct lxc_handler *handler)
>  		return -1;
>  	}
>  
> +	if (lxc_conf->is_execute)
> +		lxc_execute_bind_init(lxc_conf);
> +
>  	/* now mount only cgroup, if wanted;
>  	 * before, /sys could not have been mounted
>  	 * (is either mounted automatically or via fstab entries)
> -- 
> 1.9.1
> 
> _______________________________________________
> 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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