[pkg-gnupg-maint] Bug#841143: False assumptions about nPth (was: Bug#841143: Suspected race in gpg1 to gpg2 conversion or agent startup)

[NIIBE Yutaka]

Ian Jackson <ijackson at chiark.greenend.org.uk> wrote:
> I think that at least my patch
>   [PATCH 4/4] gpg agent lockup fix: Interrupt main loop when active_connections_value==0
> is very likely a fix to an actual race.
[...]
> I would like this bug fixed in stretch.

I think that this issue is a bug in the patches of
debian/patches/gpg-agent-idling/.

I confirmed the possibility where the main thread might block at
npth_pselect forever.  There are connections, shutdown_pending is set by
signal, npth_pselect is called, then connections are finished.  The main
thread keeps staying at npth_pselect.

For me, it is a bit difficult to apply the fourth patch only.  So, I
seek the update of the patch:

    0003-agent-Avoid-tight-timer-tick-when-possible.patch

How about changing the need_tick function, instead?  My intention is to
make the behavior of gpg-agent as similar as upstream version.

I mean, changing the first hunk of the patch of gnupg/agent/gpg-agent.c,
like this (adding the check against shutdown_pending).

--- gnupg.orig/agent/gpg-agent.c
+++ gnupg/agent/gpg-agent.c
@@ -2267,6 +2267,29 @@ create_directories (void)
 }
 
 
+static int
+need_tick (void)
+{
+#ifdef HAVE_W32_SYSTEM
+  /* We do not know how to interrupt the select loop on Windows, so we
+     always need a short tick there. */
+  return 1;
+#else
+  /* if we were invoked like "gpg-agent cmd arg1 arg2" then we need to
+     watch our parent. */
+  if (parent_pid != (pid_t)(-1))
+    return 1;
+  /* if scdaemon is running, we need to check that it's alive */
+  if (agent_scd_check_running ())
+    return 1;
+  /* if a shutdown was requested, we wait all connections closing.  */
+  if (shutdown_pending)
+    return 1;
+  /* otherwise, nothing fine-grained to do. */
+  return 0;
+#endif /*HAVE_W32_SYSTEM*/
+}
+
 
 /* This is the worker for the ticker.  It is called every few seconds
    and may only do fast operations. */
--