Re: [Xen-devel] [PATCH] Fix bug #709 by daemonizing blktapctrl and closing stdin, stdout and stderr

[Harry Butterworth <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

On Mon, 2006-07-31 at 20:31 +0300, Muli Ben-Yehuda wrote:
> On Mon, Jul 31, 2006 at 04:15:42PM +0100, Harry Butterworth wrote:
> 
> > +static void daemonize(void)
> > +{
> > +   pid_t pid;
> > +
> > +   /* Separate from our parent via fork, so init inherits us. */
> > +   if ((pid = fork()) < 0)
> > +           DPRINTF("Failed to fork daemon\n");
> 
> It will be useful to know why fork() failed (i.e., print errno
> directly or use sterror_r() and friends).
> 
> > +   if (pid != 0)
> > +           exit(0);
> 
> If fork() failed, this will cause us to exit(0) which doesn't seem
> particularly appropriate.
> 
> > +   /* Session leader so ^C doesn't whack us. */
> > +   setsid();
> 
> In theory setsid() can fail.
> 
> > +   /* Let session leader exit so child cannot regain CTTY */
> > +   if ((pid = fork()) < 0)
> > +           DPRINTF("Failed to fork daemon\n");
> > +   if (pid != 0)
> > +           exit(0);
> 
> Same comment as above.
> > +
> > +#ifndef TESTING    /* Relative paths for socket names */
> > +   /* Move off any mount points we might be in. */
> > +   if (chdir("/") == -1)
> > +           DPRINTF("Failed to chdir\n");
> > +#endif
> > +   /* Discard our parent's old-fashioned umask prejudices. */
> > +   umask(0);

OK so when I copied the code from xenstored_core.c I failed to notice
that barf_perror exits with an error code and DPRINTF which I replaced
it with doesn't.

That was pretty lame.

I'll fix these.

> > +
> > +        close(STDIN_FILENO);
> 
> Mixed tabs and spaces, ugh.

My mistake.

>  Also, fileno(stdin) is nicer.

Why? I don't think so.

> 
> Cheers,
> Muli



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel