util: Add setcap_net_raw API

Some binaries such as osmo-bts-ocpty require specific capabilities, and
we need to provide them in case osmo-gsm-tester is not run as root.

Process class from process module is imported inside the method after
module initialization in order to avoid circular dependency of relative
imports, which is only available since python 3.5.

Change-Id: If3eb24461c02173dc80837a4cc83f9f2420c7816

src/osmo_gsm_tester/util.py

@@ -49,6 +49,19 @@ def ip_to_iface(ip):
         pass
     return None
 
+def setcap_net_raw(binary, run_dir):
+    '''
+    This functionality requires specific setup on the host running
+    osmo-gsm-tester. See osmo-gsm-tester manual for more information.
+    '''
+    from .process import Process
+    SETCAP_NET_BIN = 'osmo-gsm-tester_setcap_net_raw.sh'
+    proc = Process(SETCAP_NET_BIN, run_dir, ['sudo', 'osmo-gsm-tester_setcap_net_raw.sh', binary])
+    proc.launch()
+    proc.wait()
+    if proc.result != 0:
+        raise RuntimeError('%s finished with err code %d' % (SETCAP_NET_BIN, proc.result))
+
 class listdict(dict):
     'a dict of lists { "a": [1, 2, 3],  "b": [1, 2] }'