ZyklonB: run plugins in a special work directory

Also small refactoring.

zyklonb.c

@@ -1021,16 +1021,12 @@ is_valid_plugin_name (const char *name)
 	return true;
 }
 
-static bool
+static struct plugin *
-plugin_load (struct bot_context *ctx, const char *name, struct error **e)
+plugin_launch (struct bot_context *ctx, const char *name, struct error **e)
 {
 	const char *plugin_dir = str_map_find (&ctx->config, "plugin_dir");
 	if (!plugin_dir)
 		FAIL ("plugin directory not set");
-	if (!is_valid_plugin_name (name))
-		FAIL ("invalid plugin name");
-	if (str_map_find (&ctx->plugins_by_name, name))
-		FAIL ("the plugin has already been loaded");
 
 	int stdin_pipe[2];
 	if (pipe (stdin_pipe) == -1)
@@ -1043,6 +1039,14 @@ plugin_load (struct bot_context *ctx, const char *name, struct error **e)
 		goto fail_1;
 	}
 
+	struct str work_dir;
+	str_init (&work_dir);
+	get_xdg_home_dir (&work_dir, "XDG_DATA_HOME", ".local/share");
+	str_append_printf (&work_dir, "/%s", PROGRAM_NAME);
+
+	if (!mkdir_with_parents (work_dir.str, e))
+		goto fail_2;
+
 	set_cloexec (stdin_pipe[1]);
 	set_cloexec (stdout_pipe[0]);
 
@@ -1056,36 +1060,40 @@ plugin_load (struct bot_context *ctx, const char *name, struct error **e)
 	if (pid == 0)
 	{
 		// Redirect the child's stdin and stdout to the pipes
-		hard_assert (dup2 (stdin_pipe[0],  STDIN_FILENO)  != -1);
+		if (dup2 (stdin_pipe[0], STDIN_FILENO) == -1
-		hard_assert (dup2 (stdout_pipe[1], STDOUT_FILENO) != -1);
+		 || dup2 (stdout_pipe[1], STDOUT_FILENO) == -1)
+		{
+			print_error ("%s: %s: %s", "failed to load the plugin",
+				"dup2", strerror (errno));
+			_exit (EXIT_FAILURE);
+		}
+		if (chdir (work_dir.str))
+		{
+			print_error ("%s: %s: %s", "failed to load the plugin",
+				"chdir", strerror (errno));
+			_exit (EXIT_FAILURE);
+		}
 
 		xclose (stdin_pipe[0]);
 		xclose (stdout_pipe[1]);
 
-		struct str pathname;
-		str_init (&pathname);
-		str_append (&pathname, plugin_dir);
-		str_append_c (&pathname, '/');
-		str_append (&pathname, name);
-
 		// Restore some of the signal handling
 		signal (SIGPIPE, SIG_DFL);
 
-		char *const argv[] = { pathname.str, NULL };
+		char *argv[] = { xstrdup_printf ("%s/%s", plugin_dir, name), NULL };
 		execve (argv[0], argv, environ);
 
 		// We will collect the failure later via SIGCHLD
-		print_error ("%s: %s: %s",
+		print_error ("%s: %s: %s", "failed to load the plugin",
-			"failed to load the plugin", "exec", strerror (errno));
+			"exec", strerror (errno));
 		_exit (EXIT_FAILURE);
 	}
 
+	str_free (&work_dir);
+
 	xclose (stdin_pipe[0]);
 	xclose (stdout_pipe[1]);
 
-	set_blocking (stdout_pipe[0], false);
-	set_blocking (stdin_pipe[1], false);
-
 	struct plugin *plugin = xmalloc (sizeof *plugin);
 	plugin_init (plugin);
 	plugin->ctx = ctx;
@@ -1093,6 +1101,32 @@ plugin_load (struct bot_context *ctx, const char *name, struct error **e)
 	plugin->name = xstrdup (name);
 	plugin->read_fd = stdout_pipe[0];
 	plugin->write_fd = stdin_pipe[1];
+	return plugin;
+
+fail_2:
+	str_free (&work_dir);
+	xclose (stdout_pipe[0]);
+	xclose (stdout_pipe[1]);
+fail_1:
+	xclose (stdin_pipe[0]);
+	xclose (stdin_pipe[1]);
+	return NULL;
+}
+
+static bool
+plugin_load (struct bot_context *ctx, const char *name, struct error **e)
+{
+	if (!is_valid_plugin_name (name))
+		FAIL ("invalid plugin name");
+	if (str_map_find (&ctx->plugins_by_name, name))
+		FAIL ("the plugin has already been loaded");
+
+	struct plugin *plugin;
+	if (!(plugin = plugin_launch (ctx, name, e)))
+		return false;
+
+	set_blocking (plugin->read_fd, false);
+	set_blocking (plugin->write_fd, false);
 
 	poller_fd_init (&plugin->read_event, &ctx->poller, plugin->read_fd);
 	plugin->read_event.dispatcher = (poller_fd_fn) on_plugin_readable;
@@ -1107,14 +1141,6 @@ plugin_load (struct bot_context *ctx, const char *name, struct error **e)
 
 	poller_fd_set (&plugin->read_event, POLLIN);
 	return true;
-
-fail_2:
-	xclose (stdout_pipe[0]);
-	xclose (stdout_pipe[1]);
-fail_1:
-	xclose (stdin_pipe[0]);
-	xclose (stdin_pipe[1]);
-	return false;
 }
 
 static bool