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Re: [PATCH v6 00/16] daemon-win32

From
Martin Storsjö <martin@martin.st>
Date
Nov 4, 2010, 08:52 UTC
Message-ID
<alpine.DEB.2.00.1011041026160.31519@cone.home.martin.st>
In-Reply-To
<AANLkTim4_5dgPGcw5B3U-3UH63REL4QWsWPV=mDSJJ6D@mail.gmail.com>
On Wed, 3 Nov 2010, Erik Faye-Lund wrote:
Show 64 quoted lines
> On Wed, Nov 3, 2010 at 11:18 PM, Erik Faye-Lund <kusmabite@gmail.com> wrote:
> > On Wed, Nov 3, 2010 at 10:11 PM, Pat Thoyts
> > <patthoyts@users.sourceforge.net> wrote:
> >> Erik Faye-Lund <kusmabite@gmail.com> writes:
> >>
> >>>Here's hopefully the last iteration of this series. The previous version
> >>>only got a single complain about a typo in the subject of patch 14/15, so
> >>>it seems like most controversies have been settled.
> >>
> >> I pulled this win32-daemon branch into my msysgit build tree and built
> >> it. I get the following warnings:
> >>
> >>    CC daemon.o
> >> daemon.c: In function 'service_loop':
> >> daemon.c:674: warning: dereferencing pointer 'ss.124' does break strict-aliasing rules
> >> daemon.c:676: warning: dereferencing pointer 'ss.124' does break strict-aliasing rules
> >> daemon.c:681: warning: dereferencing pointer 'ss.124' does break strict-aliasing rules
> >> daemon.c:919: note: initialized from here
> >> daemon.c:679: warning: dereferencing pointer 'sin_addr' does break strict-aliasing rules
> >> daemon.c:675: note: initialized from here
> >> daemon.c:691: warning: dereferencing pointer 'sin6_addr' does break strict-aliasing rules
> >> daemon.c:682: note: initialized from here
> >>
> >
> > Yeah, I'm aware of these. I thought those warnings were already
> > present in the Linux build, but checking again I see that that's not
> > the case. Need to investigate.
> >
> 
> OK, it's the patch "daemon: use run-command api for async serving"
> that introduce the warning. But looking closer at the patch it doesn't
> seem the patch actually introduce the strict-aliasing violation, it's
> there already. The patch only seems to change the code enough for GCC
> to start realize there's a problem. Unless I'm misunderstanding
> something vital, that is.
> 
> Anyway, here's a patch that makes it go away, I guess I'll squash it
> into the next round.
> 
> diff --git a/daemon.c b/daemon.c
> index 6eee570..d636446 100644
> --- a/daemon.c
> +++ b/daemon.c
> @@ -1159,14 +1159,13 @@ int main(int argc, char **argv)
>  	}
> 
>  	if (inetd_mode || serve_mode) {
> -		struct sockaddr_storage ss;
> -		struct sockaddr *peer = (struct sockaddr *)&ss;
> -		socklen_t slen = sizeof(ss);
> +		struct sockaddr sa;
> +		socklen_t slen = sizeof(sa);
> 
> -		if (getpeername(0, peer, &slen))
> -			peer = NULL;
> -
> -		return execute(peer);
> +		if (getpeername(0, &sa, &slen))
> +			return execute(NULL);
> +		else
> +			return execute(&sa);
>  	}
> 
>  	if (detach) {

As you noticed later yourself, this is not right. You can get any kind of sockaddr back from getpeername. I'm not sure if any spec mandates that a "normal" sockaddr_in should fit into the base sockaddr, or if that just happens by coincidence or sheer luck.

// Martin
Previous: Erik Faye-Lund
Message 31 of 31 in “daemon-win32”
  1. 00/16 daemon-win32Erik Faye-Lund, Nov 3, 2010
  2. 01/16 mingw: add network-wrappers for daemonErik Faye-Lund, Nov 3, 2010
  3. 02/16 mingw: implement syslogErik Faye-Lund, Nov 3, 2010
  4. 03/16 compat: add inet_pton and inet_ntop prototypesErik Faye-Lund, Nov 3, 2010
  5. 04/16 inet_ntop: fix a couple of old-style declsErik Faye-Lund, Nov 3, 2010
  6. 05/16 mingw: use real pidErik Faye-Lund, Nov 3, 2010
  7. 06/16 mingw: support waitpid with pid > 0 and WNOHANGErik Faye-Lund, Nov 3, 2010
  8. 07/16 mingw: add kill emulationErik Faye-Lund, Nov 3, 2010
  9. 08/16 daemon: use run-command api for async servingErik Faye-Lund, Nov 3, 2010
  10. 09/16 daemon: use full buffered mode for stderrErik Faye-Lund, Nov 3, 2010
  11. 10/16 Improve the mingw getaddrinfo stub to handle more use casesErik Faye-Lund, Nov 3, 2010
  12. 11/16 daemon: get remote host address from root-processErik Faye-Lund, Nov 3, 2010
  13. 12/16 mingw: import poll-emulation from gnulibErik Faye-Lund, Nov 3, 2010
  14. 13/16 mingw: use poll-emulation from gnulibErik Faye-Lund, Nov 3, 2010
  15. 14/16 daemon: use socklen_tErik Faye-Lund, Nov 3, 2010
  16. 15/16 daemon: make --inetd and --detach incompatibleErik Faye-Lund, Nov 3, 2010
  17. 16/16 daemon: opt-out on features that require posixErik Faye-Lund, Nov 3, 2010
  18. Pat ThoytsNov 3, 2010
  19. Erik Faye-LundNov 3, 2010
  20. Erik Faye-LundNov 3, 2010
  21. Pat ThoytsNov 4, 2010
  22. Erik Faye-LundNov 4, 2010
  23. Pat ThoytsNov 4, 2010
  24. Erik Faye-LundNov 3, 2010
  25. Erik Faye-LundNov 4, 2010
  26. Erik Faye-LundNov 4, 2010
  27. Martin StorsjöNov 4, 2010
  28. Erik Faye-LundNov 4, 2010
  29. Martin StorsjöNov 4, 2010
  30. Erik Faye-LundNov 4, 2010
  31. Martin StorsjöNov 4, 2010

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