[libvirt] [PATCH v3] util: Block SIGPIPE until execve in child process

[Eric Blake]

On 10/15/19 9:25 PM, Wang Yechao wrote:
> Libvirtd has set SIGPIPE to ignored, and virFork resets all signal
> handlers to the defaults. But child process may write logs to
> stderr/stdout, that may generate SIGPIPE if journald has stopped.
> 
> So block SIGPIPE in virFork, and unblock it before execve.

How does that help?  If writing to stderr hits EOF, it will queue up a 
SIGPIPE to be delivered as soon as you unblock SIGPIPE.

The correct fix is to not unblock SIGPIPE until after any point at which 
you would be performing I/O that must not fail due to SIGPIPE, rather 
than messing with signal masks to just delay when SIGPIPE is delivered.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org