split 'libosmocore' from openbsc codebase

This library is intended to collect all generic/common funcitionality
of all Osmocom.org projects, including OpenBSC but also OsmocomBB

The library currently includes the following modules:

bitvec, comp128, gsm_utils, msgb, select, signal, statistics, talloc, timer,
tlv_parse, linuxlist

msgb allocation error debugging had to be temporarily disabled as it depends on
'debug.c' functionality which at the moment remains in OpenBSC
diff --git a/libosmocore/src/signal.c b/libosmocore/src/signal.c
new file mode 100644
index 0000000..c7ca86c
--- /dev/null
+++ b/libosmocore/src/signal.c
@@ -0,0 +1,84 @@
+/* Generic signalling/notification infrastructure */
+/* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <osmocore/signal.h>
+#include <osmocore/talloc.h>
+#include <osmocore/linuxlist.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+void *tall_sigh_ctx;
+static LLIST_HEAD(signal_handler_list);
+
+struct signal_handler {
+	struct llist_head entry;
+	unsigned int subsys;
+	signal_cbfn *cbfn;
+	void *data;
+};
+
+
+int register_signal_handler(unsigned int subsys, signal_cbfn *cbfn, void *data)
+{
+	struct signal_handler *sig_data;
+
+	sig_data = talloc(tall_sigh_ctx, struct signal_handler);
+	if (!sig_data)
+		return -ENOMEM;
+
+	memset(sig_data, 0, sizeof(*sig_data));
+
+	sig_data->subsys = subsys;
+	sig_data->data = data;
+	sig_data->cbfn = cbfn;
+
+	/* FIXME: check if we already have a handler for this subsys/cbfn/data */
+
+	llist_add_tail(&sig_data->entry, &signal_handler_list);
+
+	return 0;
+}
+
+void unregister_signal_handler(unsigned int subsys, signal_cbfn *cbfn, void *data)
+{
+	struct signal_handler *handler;
+
+	llist_for_each_entry(handler, &signal_handler_list, entry) {
+		if (handler->cbfn == cbfn && handler->data == data 
+		    && subsys == handler->subsys) {
+			llist_del(&handler->entry);
+			talloc_free(handler);
+			break;
+		}
+	}
+}
+
+
+void dispatch_signal(unsigned int subsys, unsigned int signal, void *signal_data)
+{
+	struct signal_handler *handler;
+
+	llist_for_each_entry(handler, &signal_handler_list, entry) {
+		if (handler->subsys != subsys)
+			continue;
+		(*handler->cbfn)(subsys, signal, handler->data, signal_data);
+	}
+}