s4:process_modals Add another process modal - 'onefork'

This will fork off exactly one child to handle some task, ensuring
that if it dies or changes global state, that this does not change
everything.

Andrew Bartlett

3 files changed, 183 insertions, 0 deletions

diff --git a/source4/smbd/process_model.c b/source4/smbd/process_model.c
index e3ea4dbf39..d3f234eb41 100644
--- a/source4/smbd/process_model.c
+++ b/source4/smbd/process_model.c
@@ -86,6 +86,7 @@ _PUBLIC_ NTSTATUS process_model_init(struct loadparm_context *lp_ctx)
 	extern NTSTATUS process_model_thread_init(void);
 	extern NTSTATUS process_model_standard_init(void);
 	extern NTSTATUS process_model_prefork_init(void);
+	extern NTSTATUS process_model_onefork_init(void);
 	extern NTSTATUS process_model_single_init(void);
 	init_module_fn static_init[] = { STATIC_process_model_MODULES };
 	init_module_fn *shared_init = load_samba_modules(NULL, lp_ctx, "process_model");
diff --git a/source4/smbd/process_onefork.c b/source4/smbd/process_onefork.c
new file mode 100644
index 0000000000..45e461327c
--- /dev/null
+++ b/source4/smbd/process_onefork.c
@@ -0,0 +1,175 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   process model: onefork (1 child process)
+
+   Copyright (C) Andrew Tridgell 1992-2005
+   Copyright (C) James J Myers 2003 <myersjj@samba.org>
+   Copyright (C) Stefan (metze) Metzmacher 2004
+   Copyright (C) Andrew Bartlett 2008 <abartlet@samba.org>
+   Copyright (C) David Disseldorp 2008 <ddiss@sgi.com>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "lib/events/events.h"
+#include "lib/socket/socket.h"
+#include "smbd/process_model.h"
+#include "param/secrets.h"
+#include "system/filesys.h"
+#include "cluster/cluster.h"
+#include "param/param.h"
+#include "lib/ldb_wrap.h"
+
+#ifdef HAVE_SETPROCTITLE
+#ifdef HAVE_SETPROCTITLE_H
+#include <setproctitle.h>
+#endif
+#else
+#define setproctitle none_setproctitle
+static int none_setproctitle(const char *fmt, ...) PRINTF_ATTRIBUTE(1, 2);
+static int none_setproctitle(const char *fmt, ...)
+{
+	return 0;
+}
+#endif
+
+/*
+  called when the process model is selected
+*/
+static void onefork_model_init(struct tevent_context *ev)
+{
+	signal(SIGCHLD, SIG_IGN);
+}
+
+static void onefork_reload_after_fork(void)
+{
+	ldb_wrap_fork_hook();
+
+	/* Ensure that the forked children do not expose identical random streams */
+	set_need_random_reseed();
+}
+
+/*
+  called when a listening socket becomes readable.
+*/
+static void onefork_accept_connection(struct tevent_context *ev,
+				      struct loadparm_context *lp_ctx,
+				      struct socket_context *listen_socket,
+				       void (*new_conn)(struct tevent_context *,
+							struct loadparm_context *, struct socket_context *,
+							struct server_id , void *),
+				       void *private_data)
+{
+	NTSTATUS status;
+	struct socket_context *connected_socket;
+	pid_t pid = getpid();
+
+	/* accept an incoming connection. */
+	status = socket_accept(listen_socket, &connected_socket);
+	if (!NT_STATUS_IS_OK(status)) {
+		return;
+	}
+
+	talloc_steal(private_data, connected_socket);
+
+	new_conn(ev, lp_ctx, connected_socket, cluster_id(pid, socket_get_fd(connected_socket)), private_data);
+}
+
+/*
+  called to create a new server task
+*/
+static void onefork_new_task(struct tevent_context *ev,
+			     struct loadparm_context *lp_ctx,
+			     const char *service_name,
+			     void (*new_task_fn)(struct tevent_context *, struct loadparm_context *lp_ctx, struct server_id , void *),
+			     void *private_data)
+{
+	pid_t pid;
+	int i, num_children;
+
+	struct tevent_context *ev2, *ev_parent;
+
+	pid = fork();
+
+	if (pid != 0) {
+		/* parent or error code ... go back to the event loop */
+		return;
+	}
+
+	pid = getpid();
+
+	/* This is now the child code. We need a completely new event_context to work with */
+	ev2 = s4_event_context_init(NULL);
+
+	/* setup this as the default context */
+	s4_event_context_set_default(ev2);
+
+	/* the service has given us a private pointer that
+	   encapsulates the context it needs for this new connection -
+	   everything else will be freed */
+	talloc_steal(ev2, private_data);
+
+	/* this will free all the listening sockets and all state that
+	   is not associated with this new connection */
+	talloc_free(ev);
+
+	setproctitle("task %s server_id[%d]", service_name, pid);
+
+	onefork_reload_after_fork();
+
+	/* setup this new connection: process will bind to it's sockets etc */
+	new_task_fn(ev2, lp_ctx, cluster_id(pid, 0), private_data);
+
+	event_loop_wait(ev2);
+
+	talloc_free(ev2);
+	exit(0);
+
+}
+
+
+/* called when a task goes down */
+static void onefork_terminate(struct tevent_context *ev, struct loadparm_context *lp_ctx, const char *reason)
+{
+	DEBUG(2,("onefork_terminate: reason[%s]\n",reason));
+}
+
+/* called to set a title of a task or connection */
+static void onefork_set_title(struct tevent_context *ev, const char *title)
+{
+	if (title) {
+		setproctitle("%s", title);
+	} else {
+		setproctitle(NULL);
+	}
+}
+
+static const struct model_ops onefork_ops = {
+	.name			= "onefork",
+	.model_init		= onefork_model_init,
+	.accept_connection	= onefork_accept_connection,
+	.new_task               = onefork_new_task,
+	.terminate              = onefork_terminate,
+	.set_title              = onefork_set_title,
+};
+
+/*
+  initialise the onefork process model, registering ourselves with the process model subsystem
+ */
+NTSTATUS process_model_onefork_init(void)
+{
+	return register_process_model(&onefork_ops);
+}
diff --git a/source4/smbd/wscript_build b/source4/smbd/wscript_build
index 22a1d6b478..131741153c 100644
--- a/source4/smbd/wscript_build
+++ b/source4/smbd/wscript_build
@@ -59,6 +59,13 @@ bld.SAMBA_MODULE('process_model_prefork',
 	deps='LIBEVENTS SETPROCTITLE'
 	)
 
+bld.SAMBA_MODULE('process_model_onefork',
+	source='process_onefork.c',
+	subsystem='process_model',
+	init_function='process_model_onefork_init',
+	deps='LIBEVENTS SETPROCTITLE'
+	)
+
 
 bld.SAMBA_SUBSYSTEM('process_model',
 	source='process_model.c',