Re: runit - access to run script's exit status for finish?

[Gerrit Pape <pape@smarden.org>]

On Mon, Sep 12, 2005 at 10:11:58AM -0500, Charles Duffy wrote:
> Gerrit Pape wrote:
> >This sounds like a very good idea.  I didn't re-check, but it should be
> >possible to extend the supervise/status file by two bytes, being the
> >last return code from ./run and ./finish, initially 0, without breaking
> >backward compatibility.
> 
> From what I've seen from the code so far, I agree that there shouldn't 
> be backwards-compatibility issues.
> 
> However, on actually attempting to implement the interface we discussed, 
> I've found it to be somewhat inadequate: It permits the user to retrieve 
> the last exit status, but does *not* have any way to track there has 
> been any exit at all within this run, nor whether the program terminated 
> via a signal without calling exit() [and thus without setting an exit 
> status].
> 
> I'm considering extending by sizeof(int)*2 and storing wait()'s output 
> verbatim; that way, WIFEXITED/WIFSIGNALED/WTERMSIG/WEXITSTATUS are all 
> available, and it's possible to determine if the last exit was via a 
> signal (and if so, what).
> 
> This leaves open the question of how to expose this information to the 
> user. I'm considering the following:
> 
>  -r: last exit type and value for ./run
>  -f: last exit type and value for ./finish
> 
> could return instead of <rc>, <type>:<rc>, as in "signal:11", "exit:0", 
> "exit:1" or "none:0" (if there has, as of yet, been no exit).
> 
> Thoughts?

It's a good idea to include this additional information into
supervise/status.  What I'm not sure about is the output "<type>:<rc>".
How about simply having the exit code (0-255) printed if ./run
terminated cleanly, the signal number prefixed with '-' if it
terminated due to an uncatched signal, and nothing if ./run didn't
terminate at all yet?:

 # sv status -r .
 0
 # 
./run terminated with return code 0.

 # sv status -r .
 -13
 # 
./run terminated due to uncatched SIGPIPE.

 # sv status -r .
 # 
./run didn't terminate yet, since the supervisor started.

Regards, Gerrit.