introduce HAVE_TM_GMTOFF_IN_TM

Not all architectures have the tm.tm_gmtoff member.  This fixes cygwin
builds.

1 files changed, 24 insertions, 0 deletions

diff --git a/openbsc/configure.ac b/openbsc/configure.ac
index 56e4b60ad..16eb732b6 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -83,6 +83,30 @@ if test "$enable_coverage" = "yes"; then
    AC_SUBST([COVERAGE_LDFLAGS])
 fi
 
+AC_DEFUN([CHECK_TM_INCLUDES_TM_GMTOFF], [
+  AC_CACHE_CHECK(
+    [whether struct tm has tm_gmtoff member],
+    osmo_cv_tm_includes_tm_gmtoff,
+    [AC_LINK_IFELSE([
+      AC_LANG_PROGRAM([
+        #include <time.h>
+      ], [
+        time_t t = time(NULL);
+        struct tm* lt = localtime(&t);
+        int off = lt->tm_gmtoff;
+      ])
+    ],
+    osmo_cv_tm_includes_tm_gmtoff=yes,
+    osmo_cv_tm_includes_tm_gmtoff=no
+    )]
+  )
+  if test "x$osmo_cv_tm_includes_tm_gmtoff" = xyes; then
+    AC_DEFINE(HAVE_TM_GMTOFF_IN_TM, 1,
+              [Define if struct tm has tm_gmtoff member.])
+  fi
+])
+
+CHECK_TM_INCLUDES_TM_GMTOFF
 
 dnl Generate the output
 AM_CONFIG_HEADER(bscconfig.h)