linux: use json in get_systemd_status if systemd version > 239

Signed-off-by: Adam Trhon <adam.trhon@tbs-biometrics.com>

Author: adam-trhon

labgridhelper/linux.py

@@ -1,4 +1,5 @@
 from labgrid.protocol import CommandProtocol
+import json
 import re
 
 def get_systemd_version(command):
@@ -21,39 +22,81 @@ def get_systemd_version(command):
     return int(parsed.group("version"))
 
 def get_systemd_status(command):
+    """Returns parsed output of systemd Manager's ListUnits DBus command
+
+    Args:
+        command (CommandProtocol): An instance of a Driver implementing the CommandProtocol
+
+    Returns:
+        dict: dictionary of service names to their properties
+    """
     assert isinstance(command, CommandProtocol), "command must be a CommandProtocol"
-    # TODO: Use busctl --json if systemd>239
     array_notation = "a(ssssssouso)"
-    out = command.run_check(
-        "busctl call --no-pager org.freedesktop.systemd1 \
-        /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager ListUnits"
-    )
 
-    out = out[0]
-    if array_notation not in out:
-        raise ValueError("Systemd ListUnits output changed")
-    out = out[len(array_notation):]
-    array_length = int(out[:out.index('"')].strip(" "))
-    out = out[out.index('"')+1:-1]
-    out = out.split('\" \"')
-    data = iter(out)
-    services = {}
-    for _ in range(array_length):
-        name = next(data)
-        services[name] = {}
-        services[name]["description"] = next(data)
-        services[name]["load"] = next(data)
-        services[name]["active"] = next(data)
-        services[name]["sub"] = next(data)
-        services[name]["follow"] = next(data)
-        path_and_id = next(data)
-        pos = path_and_id.index('"')
-        services[name]["path"] = path_and_id[:pos]
-        services[name]["id"] = int(path_and_id[pos+1:-1].strip(" "))
-        services[name]["type"] = path_and_id[path_and_id.rfind('"'):]
-        services[name]["objpath"] = next(data)
-
-    return services
+    def get_systemd_status_json(command):
+        out = command.run_check(
+            "busctl call --json=short --no-pager org.freedesktop.systemd1 \
+            /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager ListUnits"
+        )
+        out = out[0]
+        out = json.loads(out)
+        if out["type"] != array_notation:
+            raise ValueError("Systemd ListUnits output changed")
+
+        services = {}
+        for record in out["data"][0]:
+            data = iter(record)
+            name = next(data)
+            services[name] = {}
+            services[name]["description"] = next(data)
+            services[name]["load"] = next(data)
+            services[name]["active"] = next(data)
+            services[name]["sub"] = next(data)
+            services[name]["follow"] = next(data)
+            services[name]["path"] = next(data)
+            services[name]["id"] = int(next(data))
+            services[name]["type"] = next(data)
+            services[name]["objpath"] = next(data)
+
+        return services
+
+    def get_systemd_status_raw(command):
+        out = command.run_check(
+            "busctl call --no-pager org.freedesktop.systemd1 \
+            /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager ListUnits"
+        )
+
+        out = out[0]
+        if array_notation not in out:
+            raise ValueError("Systemd ListUnits output changed")
+        out = out[len(array_notation):]
+        array_length = int(out[:out.index('"')].strip(" "))
+        out = out[out.index('"')+1:-1]
+        out = out.split('\" \"')
+        data = iter(out)
+        services = {}
+        for _ in range(array_length):
+            name = next(data)
+            services[name] = {}
+            services[name]["description"] = next(data)
+            services[name]["load"] = next(data)
+            services[name]["active"] = next(data)
+            services[name]["sub"] = next(data)
+            services[name]["follow"] = next(data)
+            path_and_id = next(data)
+            pos = path_and_id.index('"')
+            services[name]["path"] = path_and_id[:pos]
+            services[name]["id"] = int(path_and_id[pos+1:-1].strip(" "))
+            services[name]["type"] = path_and_id[path_and_id.rfind('"'):]
+            services[name]["objpath"] = next(data)
+
+        return services
+
+    if get_systemd_version(command) > 239:
+        return get_systemd_status_json(command)
+    else:
+        return get_systemd_status_raw(command)
+
 
 def get_commands(command, directories=None):
     """Returns the commands of a running linux system