Add working_dir param to "execute" directive

docs/installers.rst

@@ -193,7 +193,7 @@ Example:
 Making a file executable
 ------------------------
 
-Marking the file as executable is done with the ``chmodx`` command. It is often
+Marking the file as executable is done with the ``chmodx`` directive. It is often
 needed for games that ship in a zip file, which does not retain file
 permissions.
 
@@ -204,7 +204,8 @@ Executing a file
 
 Execute files with the ``execute`` directive. Use the ``file`` parameter to
 reference a ``file id`` or a path, ``args`` to add command arguments,
-``terminal`` (set to "true") to execute in a new terminal window.
+``terminal`` (set to "true") to execute in a new terminal window, ``working_dir``
+to set the directory to execute the command in (defaults to the install path).
 The command is executed within the Lutris Runtime (resolving most shared
 library dependencies). The file is made executable if necessary, no need to run
 chmodx before.

lutris/installer/commands.py

@@ -53,6 +53,7 @@ class CommandsMixin(object):
         """Run an executable file."""
         args = []
         terminal = None
+        working_dir = None
         if isinstance(data, dict):
             self._check_required_params('file', data, 'execute')
             file_ref = data['file']
@@ -60,6 +61,7 @@ class CommandsMixin(object):
             for arg in shlex.split(args_string):
                 args.append(self._substitute(arg))
             terminal = data.get('terminal')
+            working_dir = data.get('working_dir')
         else:
             file_ref = data
 
@@ -77,6 +79,9 @@ class CommandsMixin(object):
         if terminal:
             terminal = system.get_default_terminal()
 
+        if not working_dir or not os.path.exists(working_dir):
+            working_dir = self.target_path
+
         command = [exec_path] + args
         logger.debug("Executing %s" % command)
         thread = LutrisThread(command, env=runtime.get_env(), term=terminal,