[CRIU] [PATCHv0 08/12] zdtm: implement capturing of test hooks stdout and stderr

[Eugene Batalov]

Using this feature hooks can return arbitrary data
to zdtm.py. This will be used in gc tests to tell
zdtm.py what garbage should be found by criu gc --show.

Also added function run_hook for cases when test hook always
should exist. This is needed for gc tests too.

Also this 2 features are generic and can be used in other cases.

Signed-off-by: Eugene Batalov <eabatalov89 at gmail.com>
---
 test/zdtm.py | 42 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/test/zdtm.py b/test/zdtm.py
index 230902c..2edb9bc 100755
--- a/test/zdtm.py
+++ b/test/zdtm.py
@@ -830,14 +830,40 @@ class criu_cli:
 			print "CRIU binary not built"
 			sys.exit(1)
 
-
-def try_run_hook(test, args):
-	hname = test.getname() + '.hook'
-	if os.access(hname, os.X_OK):
-		print "Running %s(%s)" % (hname, ', '.join(args))
-		hook = subprocess.Popen([hname] + args)
-		if hook.wait() != 0:
-			raise test_fail_exc("hook " + " ".join(args))
+def hook_name(test):
+	return test.getname() + '.hook'
+
+def run_hook(test, args, cap_output = False):
+	stdout_str = None
+	stderr_str = None
+
+	subproc_args = { "args" : [hook_name(test)] + args }
+	if cap_output:
+		subproc_args["stdout"] = subprocess.PIPE
+		subproc_args["stderr"] = subprocess.PIPE
+	print "Running %s" % str(subproc_args)
+	try:
+		hook = subprocess.Popen(**subproc_args)
+		if cap_output:
+			stdout_str, stderr_str = hook.communicate()
+		else:
+			hook.wait()
+		if hook.returncode != 0:
+			print "Hook %s return code %d" % (
+				hook_name(test), hook.returncode)
+			if cap_output:
+				print stdout_str
+				print stderr_str
+			raise Exception()
+	except:
+		raise test_fail_exc("hook " + " ".join(args))
+
+	return (stdout_str, stderr_str)
+
+def try_run_hook(test, args, cap_output = False):
+	if os.access(hook_name(test), os.X_OK):
+		return run_hook(test, args, cap_output)
+	return (None, None)
 
 #
 # Step by step execution
-- 
1.9.1