tests: support attaching to existing vpp

Introduce a new option DEBUG=attach to run a test against existing
already running vpp. A new target 'make test-start-gdb' will spawn VPP
in gdb for this purpose. Customization options explained in test-help.

Type: improvement
Change-Id: Ia160a85b33da3b2df292d44bb95729af9dd9da96
Signed-off-by: Klement Sekera <ksekera@cisco.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/test/debug.py b/test/debug.py
index d1c89c66f3c..e79f082615d 100644
--- a/test/debug.py
+++ b/test/debug.py
@@ -4,6 +4,9 @@ import os
 import pexpect
 import sys
 
+from sanity_run_vpp import SanityTestCase
+from shutil import rmtree
+
 gdb_path = '/usr/bin/gdb'
 
 
@@ -22,3 +25,40 @@ def spawn_gdb(binary_path, core_path):
     else:
         sys.stderr.write("Debugger '%s' does not exist or is not "
                          "an executable..\n" % gdb_path)
+
+
+def start_vpp_in_gdb():
+    # here we use SanityTestCase as a dummy to inherit functionality,
+    # but any test case class could be used ...
+    SanityTestCase.set_debug_flags("attach")
+    SanityTestCase.tempdir = SanityTestCase.get_tempdir()
+    if os.path.exists(SanityTestCase.tempdir):
+        if os.getenv("VPP_IN_GDB_NO_RMDIR", "0") in ["1", "y", "yes"]:
+            raise FileExistsError(
+                "Temporary directory exists and removal denied.")
+        print("Removing existing temp dir '%s'." % SanityTestCase.tempdir)
+        rmtree(SanityTestCase.tempdir)
+    print("Creating temp dir '%s'." % SanityTestCase.tempdir)
+    os.mkdir(SanityTestCase.tempdir)
+    SanityTestCase.setUpConstants()
+    vpp_cmdline = SanityTestCase.vpp_cmdline
+    if os.getenv("VPP_IN_GDB_CMDLINE", "y").lower() in ["1", "y", "yes"]:
+        print("Hacking cmdline to make VPP interactive.")
+        vpp_cmdline.insert(vpp_cmdline.index("nodaemon"), "interactive")
+    print("VPP cmdline is %s" % " ".join(vpp_cmdline))
+    print("Running GDB.")
+
+    if os.path.isfile(gdb_path) and os.access(gdb_path, os.X_OK):
+        gdb_cmdline = "%s --args %s " % (gdb_path, " ".join(vpp_cmdline))
+        print("GDB cmdline is %s" % gdb_cmdline)
+        gdb = pexpect.spawn(gdb_cmdline)
+        gdb.interact()
+        try:
+            gdb.terminate(True)
+        except:
+            pass
+        if gdb.isalive():
+            raise Exception("GDB refused to die...")
+    else:
+        sys.stderr.write("Debugger '%s' does not exist or is not "
+                         "an executable..\n" % gdb_path)