[CRIU] [PATCH 3/2] libcriu: Ability to fetch arguments from notifications

[Andrew Vagin]

On Thu, Jun 26, 2014 at 02:06:44PM +0400, Pavel Emelyanov wrote:
> After a bit more thinking I found a way to fetch arguments
> from notifications -- pass opaque value into callback and
> provide a set of calls for exploring one.
> 
> With this we can
> 
> a) provide more data if service supplies additional fields
>    in the future
> b) not check the action name to decide whether or not the
>    requested argument is available
> 
> Signed-off-by: Pavel Emelyanov <xemul at parallels.com>
> ---
>  lib/criu.c | 11 ++++++++---
>  lib/criu.h | 15 ++++++++++++++-
>  2 files changed, 22 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/criu.c b/lib/criu.c
> index a827671..7653ff1 100644
> --- a/lib/criu.c
> +++ b/lib/criu.c
> @@ -19,7 +19,7 @@ const char *criu_lib_version = CRIU_VERSION;
>  
>  static char *service_address = CR_DEFAULT_SERVICE_ADDRESS;
>  static CriuOpts *opts;
> -static int (*notify)(char *action);
> +static int (*notify)(char *action, criu_notify_arg_t na);
>  static int saved_errno;
>  
>  void criu_set_service_address(char *path)
> @@ -47,13 +47,18 @@ int criu_init_opts(void)
>  	return 0;
>  }
>  
> -void criu_set_notify(int (*cb)(char *action))
> +void criu_set_notify(int (*cb)(char *action, criu_notify_arg_t na))

Could we change names on criu_set_callback? IMHO it sounds better.

>  {
>  	notify = cb;
>  	opts->has_notify_scripts = true;
>  	opts->notify_scripts = true;
>  }
>  
> +int criu_notify_pid(criu_notify_arg_t na)

criu_callback_pid

> +{
> +	return na->has_pid ? na->pid : 0;
> +}
> +
>  void criu_set_pid(int pid)
>  {
>  	opts->has_pid	= true;
> @@ -275,7 +280,7 @@ again:
>  
>  	if ((*resp)->type == CRIU_REQ_TYPE__NOTIFY) {
>  		if (notify)
> -			ret = notify((*resp)->notify->script);
> +			ret = notify((*resp)->notify->script, (*resp)->notify);
>  
>  		ret = send_notify_ack(fd, ret);
>  		if (!ret)
> diff --git a/lib/criu.h b/lib/criu.h
> index c994fd6..7950206 100644
> --- a/lib/criu.h
> +++ b/lib/criu.h
> @@ -42,7 +42,20 @@ void criu_set_log_level(int log_level);
>  void criu_set_log_file(char *log_file);
>  void criu_set_cpu_cap(unsigned int cap);
>  int criu_set_exec_cmd(int argc, char *argv[]);
> -void criu_set_notify(int (*cb)(char *action));
> +
> +/*
> + * The criu_notify_arg_t na argument is an opaque
> + * value that callbacks (cb-s) should pass into
> + * criu_notify_xxx() calls to fetch arbitrary values
> + * from notification. If the value is not available
> + * some non-existing one is reported.
> + */
> +
> +typedef struct _CriuNotify *criu_notify_arg_t;
> +void criu_set_notify(int (*cb)(char *action, criu_notify_arg_t na));
> +
> +/* Get pid of root task. 0 if not available */
> +int criu_notify_pid(criu_notify_arg_t na);
>  
>  /* Here is a table of return values and errno's of functions
>   * from the list down below.
> -- 
> 1.8.4.2
> 
> 
> _______________________________________________
> CRIU mailing list
> CRIU at openvz.org
> https://lists.openvz.org/mailman/listinfo/criu