Re: duplicate delivery with Solaris

[mea@nic.funet.fi]

> Synopsis: Two (concurrent) router processes work on same message with Solaris
> Zmailer: 2.99.48p6 but probably other versions as well.
> OS:	Solaris 2.5 but probably Solaris versions as noted below.

  ChangeLog file has:

Fri Feb 14 20:29:25 1997  Matti Aarnio  <mea@mea.tmt.tele.fi>

	* lib/esyslib.c: erename(), eqrename()
	    Rewrote  eqrename()  cleanly in model of Andy Poling's
	    ideas -- he observed surprising amounts of duplicate
	    delivery while using  rename(2) instead of link(2)/unlink(2)
	    systemcalls for acquiring a lock on the messages.

  And yes, that was about Solaris..

  Now how could we write code so that it survives this Solaris feature ?
  Perhaps:  (And this code is written in email only, not tested on
		compiler, nor in any system...)

int
erename(from, to)
	char *from, *to;
{

#ifdef	HAVE_RENAME

	while (rename(from, to) < 0) {
	  if (errno == EBUSY || errno = EINTR)
		continue; /* Sigh, solaris BUSY.. */
	  fprintf(stderr, "%s: rename(%s,%s): %s\n", progname,
		  from, to, strerror(errno));
	  return -1;
	}

#else	/* !HAVE_RENAME */
	
redo_unlink:
	while (unlink(to) < 0) {
	  if (errno == ENOENT) break; /* Ok! */
	  if (errno == EBUSY || errno == EINTR)
		continue; /* Sigh, solaris... */
	  fprintf(stderr, "%s: rename(%s,%s): %s\n", progname,
		  from, to, strerror(errno));
	  return -1;
	}
	while (link(from, to) < 0) {
	  if (errno == EEXIST)
		goto redo_unlink;
	  if (errno == EBUSY || errno == EINTR)
		continue; /* Sigh, Solaris */
	  fprintf(stderr, "%s: rename(%s,%s): %s\n", progname,
		  from, to, strerror(errno));
	  return -1;
	}

	while (unlink(from) < 0) {
	  if (errno == ENOENT) break;
	  if (errno == EBUSY) continue; /* Sigh, Solaris */
	  fprintf(stderr, "%s: rename(%s,%s): %s\n", progname,
		  from, to, strerror(errno));
	  while (unlink(to) < 0) {
	    if (errno == ENOENT) break;
	  }
	  return -1;
	}
#endif	/* !HAVE_RENAME */

	return 0;
}


	(and likewise for  eqrename() )

....
> Peter Ip/Michael Simms/Alex Nishri
> Network Services
> University of Toronto

/Matti Aarnio <mea@nic.funet.fi>