On Fri, 2020-08-21 at 18:59 +0800, Zhiqiang Liu wrote:
> sd_notify_status() is very similar with daemon_status(), except
> DAEMON_IDLE and DAEMON_RUNNING state. As suggested by Martin,
> we can create the sd notification string in a dynamic buffer,
> and treat DAEMON_IDLE and DAEMON_RUNNING cases first. Then,
> we can use daemon_status_msg[state] for other cases.
> 
> Signed-off-by: Zhiqiang Liu <[email protected]>
> Signed-off-by: lixiaokeng <[email protected]>
> ---
>  multipathd/main.c | 36 ++++++++++++++++--------------------
>  1 file changed, 16 insertions(+), 20 deletions(-)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 62cf4ff4..4ba015bb 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -85,6 +85,7 @@
> 
>  #define FILE_NAME_SIZE 256
>  #define CMDSIZE 160
> +#define MSG_SIZE 64
> 
>  #define LOG_MSG(lvl, verb, pp)                                       
> \
>  do {                                                         \
> @@ -177,28 +178,12 @@ daemon_status(void)
>   * I love you too, systemd ...
>   */
>  #ifdef USE_SYSTEMD
> -static const char *
> -sd_notify_status(enum daemon_status state)
> -{
> -     switch (state) {
> -     case DAEMON_INIT:
> -             return "STATUS=init";
> -     case DAEMON_START:
> -             return "STATUS=startup";
> -     case DAEMON_CONFIGURE:
> -             return "STATUS=configure";
> -     case DAEMON_IDLE:
> -     case DAEMON_RUNNING:
> -             return "STATUS=up";
> -     case DAEMON_SHUTDOWN:
> -             return "STATUS=shutdown";
> -     }
> -     return NULL;
> -}
> -
>  static void do_sd_notify(enum daemon_status old_state,
>                        enum daemon_status new_state)
>  {
> +     char notify_msg[MSG_SIZE];
> +     const char prefix[] = "STATUS=";
> +     const char *msg = NULL;
>       /*
>        * Checkerloop switches back and forth between idle and running
> state.
>        * No need to tell systemd each time.
> @@ -207,7 +192,18 @@ static void do_sd_notify(enum daemon_status
> old_state,
>       if ((new_state == DAEMON_IDLE || new_state == DAEMON_RUNNING)
> &&
>           (old_state == DAEMON_IDLE || old_state == DAEMON_RUNNING))
>               return;
> -     sd_notify(0, sd_notify_status(new_state));
> +
> +     if (new_state == DAEMON_IDLE || new_state == DAEMON_RUNNING)
> +             msg = "up";
> +     else
> +             msg = daemon_status_msg[new_state];
> +
> +     if (snprintf(notify_msg, MSG_SIZE, "%s%s", prefix, msg) >=
> MSG_SIZE) {
> +             condlog(2, "len of msg is should be shorter than %d",
> MSG_SIZE);

You can *prove* that this condition can never occur (actually, you'll
never need more than 17 bytes - it's ok to have some head room). The
compiler may force you to check the return value, but it's safe to
write simply

if (!safe_sprintf(notify_msg, "%s%s", prefix, msg))
       sd_notify(0, notify_msg);

No error message is necessary here.

Martin

> +             return;
> +     }
> +
> +     sd_notify(0, notify_msg);
>  }
>  #endif
> 


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