[PATCH] xap_helper: reset getopt(3) properly in workers

[Eric Wong <e@80x24.org>]

I only noticed this while doing a full -cindex --associate with
--associate-date-range=30.years.ago and --associate-max=-1 (no
limit for Xapian) between local mirrors of lore and
git.kernel.org my glibc-based system.

Apparently, glibc requires `optind = 0' to reset getopt(3) in
our workers.  Oddly, glibc appeared to work fine prior to this
change for the defaults (--associate-date-range=1.year.ago..
and --associate-max=50000).

BSDs and musl have an `optreset' variable which appear to do
the same thing, but I don't have space on BSD VMs to test full
associations.

While we're at it, we'll also keep `opterr' enabled to improve
error reporting.
---
 lib/PublicInbox/xap_helper.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index fafb392d..8602170f 100644
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -58,6 +58,12 @@
 #	define SET_MAX_EXPANSION set_max_wildcard_expansion
 #endif
 
+#if defined(__GLIBC__)
+#	define MY_DO_OPTRESET() do { optind = 0; } while (0)
+#else /* FreeBSD, musl, dfly, NetBSD, OpenBSD */
+#	define MY_DO_OPTRESET() do { optind = optreset = 1; } while (0)
+#endif
+
 #if defined(__FreeBSD__) || defined(__GLIBC__)
 #	define STDERR_ASSIGNABLE (1)
 #else
@@ -807,9 +813,9 @@ static void dispatch(struct req *req)
 	fwrite(&req->argv[0], offsetof(struct srch, paths), 1, kfp);
 
 	// global getopt variables:
-	optind = 1;
-	opterr = optopt = 0;
+	optopt = 0;
 	optarg = NULL;
+	MY_DO_OPTRESET();
 
 	// keep sync with @PublicInbox::XapHelper::SPEC
 	while ((c = getopt(req->argc, req->argv, "acd:k:m:o:rtA:O:T:")) != -1) {