[tarantool-patches] Re: [PATCH] Replace sendmsg with sendto shortcut

[Alexander Turenko]

This patch looks good to me.

Minor comments are below. It does not require you to send the patch
again. You can just answer here to comments and provide a branch with a
new version of the patch. It is usual when a patch is not changed much.

Kostya, are you have objections here?

WBR, Alexander Turenko.

> Replace sendmsg with sendto shortcut

Maybe it worth to add 'systemd:' prefix to the commit header (and start
a header with a small letter so).

On Tue, Aug 20, 2019 at 03:16:35PM +0300, Maxim Melentiev wrote:
> ping Konstantin Osipov, Alexander Turenko
> 
> Sorry, forgot to CC in initial email and then pinged in wrong thread.
> 
> On 20/08/2019 15:01, Max Melentiev (Redacted sender m.melentiev for DMARC)
> wrote:
> > There is a problem with calculating .msg_namelen field
> > of msghdr struct. Instead of
> > 
> >      .msg_name   = &sa,
> >      .msg_namelen = sizeof(sa.sun_family) + strlen(sd_unix_path),
> > 
> > it must set as
> > 
> >      .msg_namelen = sizeof(sa) // larger value than current invalid one
> > 
> > It works on linux but when I tried to enable this feature for macOS
> > it didn't (maybe because of different order of fields in the struct).
> > 
> > Instead of fixing calculation, I've replaced original sendmsg call
> > with sendto, because it's a convenient shortcut which
> > simplifies code and can prevent such mistakes.

I suggest to add 'Part of #xxxx' or 'Needed for #xxxx'.

> > ---
> > 
> > Preview: https://github.com/printercu/tarantool/commit/bc30b1093be1d03507bf84ca218b03bec5e0244a
> > 
> >   src/systemd.c | 13 ++-----------
> >   1 file changed, 2 insertions(+), 11 deletions(-)
> > 
> > diff --git a/src/systemd.c b/src/systemd.c
> > index b6c48afe2..9c0a26dd2 100644
> > --- a/src/systemd.c
> > +++ b/src/systemd.c
> > @@ -100,23 +100,14 @@ int systemd_notify(const char *message) {
> >   	struct sockaddr_un sa = {
> >   		.sun_family = AF_UNIX,
> >   	};
> > -	struct iovec vec = {
> > -		.iov_base = (char  *)message,
> > -		.iov_len  = (size_t )strlen(message)
> > -	};
> > -	struct msghdr msg = {
> > -		.msg_iov    = &vec,
> > -		.msg_iovlen = 1,
> > -		.msg_name   = &sa,
> > -	};
> > 
> > -	msg.msg_namelen = sizeof(sa.sun_family) + strlen(sd_unix_path);
> >   	strncpy(sa.sun_path, sd_unix_path, sizeof(sa.sun_path));
> >   	if (sa.sun_path[0] == '@')
> >   		sa.sun_path[0] = '\0';
> > 
> >   	say_debug("systemd: sending message '%s'", message);
> > -	ssize_t sent = sendmsg(systemd_fd, &msg, MSG_NOSIGNAL);
> > +	ssize_t sent = sendto(systemd_fd, message, (size_t)strlen(message),
> > +		MSG_NOSIGNAL, (struct sockaddr*)&sa, sizeof(sa));

Nit: As I see we usually split an asterics in a pointer type from a
pointed type with a space and also split a type in parentheses from a
value when casting. So:

(size_t)strlen(message) -> (size_t) strlen(message)
(struct sockaddr*)&sa -> (struct sockaddr *) &s

> >   	if (sent == -1) {
> >   		say_syserror("systemd: failed to send message");
> >   		return -1;
> > --
> > 2.21.0
> > 
> > 
> > .
> >