s3: Add infrastructure for background jobs

2 files changed, 272 insertions, 0 deletions

diff --git a/source3/lib/background.c b/source3/lib/background.c
new file mode 100644
index 0000000000..aa2a77d59a
--- /dev/null
+++ b/source3/lib/background.c
@@ -0,0 +1,233 @@
+/*
+   Unix SMB/CIFS implementation.
+   Regular background jobs as forked helpers
+   Copyright (C) Volker Lendecke 2012
+
+   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/util/tevent_ntstatus.h"
+#include "lib/async_req/async_sock.h"
+#include "include/messages.h"
+#include "background.h"
+
+struct background_job_state {
+	struct tevent_context *ev;
+	struct messaging_context *msg;
+	uint32_t *trigger_msgs;
+	size_t num_trigger_msgs;
+	bool parent_longlived;
+	int (*fn)(void *private_data);
+	void *private_data;
+
+	struct tevent_req *wakeup_req;
+	int pipe_fd;
+};
+
+static int background_job_state_destructor(struct background_job_state *s);
+static void background_job_waited(struct tevent_req *subreq);
+static void background_job_done(struct tevent_req *subreq);
+static void background_job_trigger(
+	struct messaging_context *msg, void *private_data, uint32_t msg_type,
+	struct server_id server_id, DATA_BLOB *data);
+
+struct tevent_req *background_job_send(TALLOC_CTX *mem_ctx,
+				       struct tevent_context *ev,
+				       struct messaging_context *msg,
+				       uint32_t *trigger_msgs,
+				       size_t num_trigger_msgs,
+				       time_t initial_wait_sec,
+				       int (*fn)(void *private_data),
+				       void *private_data)
+{
+	struct tevent_req *req, *subreq;
+	struct background_job_state *state;
+	size_t i;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct background_job_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	state->ev = ev;
+	state->msg = msg;
+
+	if (num_trigger_msgs != 0) {
+		state->trigger_msgs = (uint32_t *)talloc_memdup(
+			state, trigger_msgs,
+			sizeof(uint32_t) * num_trigger_msgs);
+		if (tevent_req_nomem(state->trigger_msgs, req)) {
+			return tevent_req_post(req, ev);
+		}
+		state->num_trigger_msgs = num_trigger_msgs;
+	}
+
+	state->fn = fn;
+	state->private_data = private_data;
+
+	state->pipe_fd = -1;
+	talloc_set_destructor(state, background_job_state_destructor);
+
+	for (i=0; i<num_trigger_msgs; i++) {
+		NTSTATUS status;
+		status = messaging_register(msg, state, trigger_msgs[i],
+					    background_job_trigger);
+		if (tevent_req_nterror(req, status)) {
+			return tevent_req_post(req, ev);
+		}
+	}
+
+	subreq = tevent_wakeup_send(
+		state, state->ev, timeval_current_ofs(initial_wait_sec, 0));
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, background_job_waited, req);
+	state->wakeup_req = subreq;
+	return req;
+}
+
+static int background_job_state_destructor(struct background_job_state *state)
+{
+	size_t i;
+	if (state->pipe_fd != -1) {
+		close(state->pipe_fd);
+		state->pipe_fd = -1;
+	}
+	for (i=0; i<state->num_trigger_msgs; i++) {
+		messaging_deregister(state->msg, state->trigger_msgs[i],
+				     state);
+	}
+	return 0;
+}
+
+static void background_job_trigger(
+	struct messaging_context *msg, void *private_data, uint32_t msg_type,
+	struct server_id server_id, DATA_BLOB *data)
+{
+	struct background_job_state *state = talloc_get_type_abort(
+		private_data, struct background_job_state);
+
+	if (state->wakeup_req != NULL) {
+		tevent_req_set_endtime(state->wakeup_req, state->ev,
+				       timeval_zero());
+	}
+}
+
+static void background_job_waited(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct background_job_state *state = tevent_req_data(
+		req, struct background_job_state);
+	int fds[2];
+	int res;
+	bool ret;
+
+	ret = tevent_wakeup_recv(subreq);
+	TALLOC_FREE(subreq);
+	state->wakeup_req = NULL;
+	if (!ret) {
+		tevent_req_nterror(req, NT_STATUS_INTERNAL_ERROR);
+		return;
+	}
+
+	res = pipe(fds);
+	if (res == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(errno));
+		return;
+	}
+
+	res = fork();
+	if (res == -1) {
+		int err = errno;
+		close(fds[0]);
+		close(fds[1]);
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+
+	if (res == 0) {
+		/* child */
+
+		NTSTATUS status;
+		ssize_t written;
+
+		close(fds[0]);
+
+		status = reinit_after_fork(state->msg, state->ev, true);
+		if (NT_STATUS_IS_OK(status)) {
+			res = state->fn(state->private_data);
+		} else {
+			res = -1;
+		}
+		written = write(fds[1], &res, sizeof(res));
+		if (written == -1) {
+			_exit(1);
+		}
+		_exit(0);
+	}
+
+	/* parent */
+
+	close(fds[1]);
+	state->pipe_fd = fds[0];
+
+	subreq = read_packet_send(state, state->ev, state->pipe_fd,
+				  sizeof(int), NULL, NULL);
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, background_job_done, req);
+}
+
+static void background_job_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct background_job_state *state = tevent_req_data(
+		req, struct background_job_state);
+	ssize_t ret;
+	uint8_t *buf;
+	int err;
+	int wait_secs;
+
+	ret = read_packet_recv(subreq, talloc_tos(), &buf, &err);
+	TALLOC_FREE(subreq);
+	if (ret == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+	close(state->pipe_fd);
+	state->pipe_fd = -1;
+	memcpy(&wait_secs, buf, sizeof(wait_secs));
+	if (wait_secs == -1) {
+		tevent_req_done(req);
+		return;
+	}
+	subreq = tevent_wakeup_send(
+		state, state->ev, timeval_current_ofs(wait_secs, 0));
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, background_job_waited, req);
+	state->wakeup_req = subreq;
+}
+
+NTSTATUS background_job_recv(struct tevent_req *req)
+{
+	return tevent_req_simple_recv_ntstatus(req);
+}
diff --git a/source3/lib/background.h b/source3/lib/background.h
new file mode 100644
index 0000000000..ccfd62bfce
--- /dev/null
+++ b/source3/lib/background.h
@@ -0,0 +1,39 @@
+/*
+   Unix SMB/CIFS implementation.
+   Regular background jobs as forked helpers
+   Copyright (C) Volker Lendecke 2012
+
+   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/>.
+*/
+
+#ifndef _LIB_BACKGROUND_H_
+#define _LIB_BACKGROUND_H_
+
+/*
+ * From a parent process regularly fork a process and execute fn(). fn()
+ * returns the number of seconds to wait before it is run next time. Returning
+ * -1 means stop the job.
+ */
+
+struct tevent_req *background_job_send(TALLOC_CTX *mem_ctx,
+				       struct tevent_context *ev,
+				       struct messaging_context *msg,
+				       uint32_t *trigger_msgs,
+				       size_t num_trigger_msgs,
+				       time_t initial_wait_sec,
+				       int (*fn)(void *private_data),
+				       void *private_data);
+NTSTATUS background_job_recv(struct tevent_req *req);
+
+#endif