From 6a6967e827e11d332598a9395adb9c578184f914 Mon Sep 17 00:00:00 2001
From: Zachary Ware <zachary.ware@gmail.com>
Date: Sat, 1 Oct 2016 00:47:27 -0500
Subject: [PATCH] Issue #21085: add configure check for siginfo_t.si_band

Patch by Masayuki Yamamoto, reviewed and rebased by Erik Bray.

This is a first step on the long road toward resupporting Cygwin, which does
not provide siginfo_t.si_band.
---
 Misc/ACKS              |  1 +
 Misc/NEWS              |  3 +++
 Modules/signalmodule.c |  4 ++++
 configure              | 12 ++++++++++++
 configure.ac           |  2 ++
 pyconfig.h.in          |  3 +++
 6 files changed, 25 insertions(+)

diff --git a/Misc/ACKS b/Misc/ACKS
index a5465a2af99..467f3aae0e4 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1671,6 +1671,7 @@ Florent Xicluna
 Arnon Yaari
 Alakshendra Yadav
 Hirokazu Yamamoto
+Masayuki Yamamoto
 Ka-Ping Yee
 Chi Hsuan Yen
 Jason Yeo
diff --git a/Misc/NEWS b/Misc/NEWS
index 8a0dac9fb5d..9d48ff8a0d6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -173,6 +173,9 @@ Windows
 Build
 -----
 
+- Issue #21085: Add configure check for siginfo_t.si_band, which Cygwin does
+  not provide.  Patch by Masayuki Yamamoto with review and rebase by Erik Bray.
+
 - Issue #28258: Fixed build with Estonian locale (python-config and distclean
   targets in Makefile).  Patch by Arfrever Frehtes Taifersar Arahesis.
 
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index e27075b2001..bc36d41648e 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -957,7 +957,11 @@ fill_siginfo(siginfo_t *si)
     PyStructSequence_SET_ITEM(result, 4, _PyLong_FromUid(si->si_uid));
     PyStructSequence_SET_ITEM(result, 5,
                                 PyLong_FromLong((long)(si->si_status)));
+#ifdef HAVE_SIGINFO_T_SI_BAND
     PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(si->si_band));
+#else
+    PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(0L));
+#endif
     if (PyErr_Occurred()) {
         Py_DECREF(result);
         return NULL;
diff --git a/configure b/configure
index 860135b2987..cff86835419 100755
--- a/configure
+++ b/configure
@@ -13087,6 +13087,18 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+fi
+
+# Issue #21085: In Cygwin, siginfo_t does not have si_band field.
+ac_fn_c_check_member "$LINENO" "siginfo_t" "si_band" "ac_cv_member_siginfo_t_si_band" "#include <signal.h>
+"
+if test "x$ac_cv_member_siginfo_t_si_band" = xyes; then :
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_SIGINFO_T_SI_BAND 1
+_ACEOF
+
+
 fi
 
 
diff --git a/configure.ac b/configure.ac
index d3956325b8b..8465afc963a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3907,6 +3907,8 @@ AC_CHECK_MEMBERS([struct passwd.pw_gecos, struct passwd.pw_passwd], [], [], [[
   #include <sys/types.h>
   #include <pwd.h>
 ]])
++# Issue #21085: In Cygwin, siginfo_t does not have si_band field.
++AC_CHECK_MEMBERS([siginfo_t.si_band], [], [], [[#include <signal.h>]])
 
 AC_MSG_CHECKING(for time.h that defines altzone)
 AC_CACHE_VAL(ac_cv_header_time_altzone,[
diff --git a/pyconfig.h.in b/pyconfig.h.in
index e7a836c5d42..bfccabe2f7a 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -856,6 +856,9 @@
 /* Define to 1 if you have the `sigaltstack' function. */
 #undef HAVE_SIGALTSTACK
 
+/* Define to 1 if `si_band' is a member of `siginfo_t'. */
+#undef HAVE_SIGINFO_T_SI_BAND
+
 /* Define to 1 if you have the `siginterrupt' function. */
 #undef HAVE_SIGINTERRUPT