Use tmpdir to create bts pcu-socket

In commit 329b6f4 pcu-socket path was moved to run inside the test run
dir to avoid issues between different tests creating a socket in the
same place.

However, it seems unix sockets paths are limited to 108 bytes (with Null
char included). In some cases, the run dir for a test can be quite long,
as it contains suite name, test name, etc. and the path can be longer
that the limit defined above.

In order to fix this issue, create a tmp dir using mkdtemp to ensure the
path to be used for the pcu-socket doesn't collide between different
instances of osmo-bts-trx.

Clean up of tmp dir and pcu socket is done inside the cleanup() method
called by suite.py.

method pcu_socket_path() is added to help with new implementation, and
it will be used as well as a public API later soon to be used by OsmoPcu
classes.

Related: OS#2507

Change-Id: I0c53a0a3ccc5eb2823265fe14c0f7b8f4adb1038

src/osmo_gsm_tester/bts_osmotrx.py

@@ -19,6 +19,7 @@
 
 import os
 import pprint
+import tempfile
 from . import log, config, util, template, process, event_loop
 
 class OsmoBtsTrx(log.Origin):
@@ -28,6 +29,7 @@ class OsmoBtsTrx(log.Origin):
     inst = None
     env = None
     trx = None
+    pcu_sk_tmp_dir = None
 
     BIN_BTS_TRX = 'osmo-bts-trx'
     BIN_PCU = 'osmo-pcu'
@@ -39,6 +41,20 @@ class OsmoBtsTrx(log.Origin):
         self.suite_run = suite_run
         self.conf = conf
         self.env = {}
+        self.pcu_sk_tmp_dir = tempfile.mkdtemp(None, 'ogtpcusk', None)
+        if len(self.pcu_socket_path().encode()) > 107:
+            raise log.Error('Path for pcu socket is longer than max allowed len for unix socket path (107):', self.pcu_socket_path())
+
+    def cleanup(self):
+        if self.pcu_sk_tmp_dir:
+            try:
+                os.remove(self.pcu_socket_path())
+            except OSError:
+                pass
+            os.rmdir(self.pcu_sk_tmp_dir)
+
+    def pcu_socket_path(self):
+        return os.path.join(self.pcu_sk_tmp_dir, 'pcu_bts')
 
     def remote_addr(self):
         return self.conf.get('addr')
@@ -105,7 +121,7 @@ class OsmoBtsTrx(log.Origin):
                             'oml_remote_ip': self.bsc.addr(),
                             'trx_local_ip': self.remote_addr(),
                             'trx_remote_ip': self.trx_remote_ip(),
-                            'pcu_socket_path': os.path.join(str(self.run_dir), 'pcu_bts')
+                            'pcu_socket_path': self.pcu_socket_path(),
                         }
         })
         config.overlay(values, { 'osmo_bts_trx': self.conf })

src/osmo_gsm_tester/bts_sysmo.py

@@ -80,6 +80,12 @@ class SysmoBts(log.Origin):
              '-i', self.bsc.addr()),
             remote_cwd=remote_run_dir)
 
+    def cleanup(self):
+        pass
+
+    def pcu_socket_path(self):
+        return os.path.join(SysmoBts.REMOTE_DIR, 'pcu_bts')
+
     def _process_remote(self, name, popen_args, remote_cwd=None):
         run_dir = self.run_dir.new_dir(name)
         return process.RemoteProcess(name, run_dir, self.remote_user, self.remote_addr(), remote_cwd,
@@ -122,7 +128,7 @@ class SysmoBts(log.Origin):
         config.overlay(values, {
                         'osmo_bts_sysmo': {
                             'oml_remote_ip': self.bsc.addr(),
-                            'pcu_socket_path': os.path.join(SysmoBts.REMOTE_DIR, 'pcu_bts')
+                            'pcu_socket_path': self.pcu_socket_path(),
                         }
         })
         config.overlay(values, { 'osmo_bts_sysmo': self.conf })

src/osmo_gsm_tester/suite.py

@@ -351,7 +351,9 @@ class SuiteRun(log.Origin):
         return osmo_stp.OsmoStp(self, ip_address)
 
     def bts(self, specifics=None):
-        return bts_obj(self, self.reserved_resources.get(resource.R_BTS, specifics=specifics))
+        bts = bts_obj(self, self.reserved_resources.get(resource.R_BTS, specifics=specifics))
+        self.register_for_cleanup(bts)
+        return bts
 
     def modem(self, specifics=None):
         conf = self.reserved_resources.get(resource.R_MODEM, specifics=specifics)