Re: runsv failing when starting up logger - missing pipe - failure of logpipe init?

[Charlie Brady <charlieb-supervision@budge.apana.org.au>]

On Mon, 16 Aug 2010, Charlie Brady wrote:

> Here's the code in runsv where the child is dying:
> 
> ...
>   if (p == 0) {
>     /* child */
>     if (haslog) {
>       if (s->islog) {
>         if (fd_copy(0, logpipe[0]) == -1)
>           fatal("unable to setup filedescriptor for ./log/run");
> ...
> 
> and here is where logpipe[0] should have been initialised:
> 
> ...
>       if (pipe(logpipe) == -1)
>         fatal("unable to create log pipe");
> ...
> 
> Has anyone else seen this error condition or can posit a situation where 
> it might be seen?

The next question to ponder is where the bug lies. The runsv process here 
has no fd 5 and fd 6 - IOW, logpipe[0] is 5, but isn't a valid fd. Are 
there circumstances where a pipe can just cease to be? Should runsv have 
detected this issue (where pipe() did not return -1, but the fds returned 
were not valid)?

Is this a linux kernel bug?