Add osmo_io with initial poll backend

* make backend configurable for later
* segmentation callback for chunked streams
* logging target for osmo_io
* support partial writes

Change-Id: I50d73cf550d6ce8154bf827bf47408131cf5b0a0
Related: SYS#5094, OS#5751
diff --git a/src/core/osmo_io_poll.c b/src/core/osmo_io_poll.c
new file mode 100644
index 0000000..95aa84a
--- /dev/null
+++ b/src/core/osmo_io_poll.c
@@ -0,0 +1,185 @@
+/*! \file osmo_io_poll.c
+ * New osmocom async I/O API.
+ *
+ * (C) 2022 by Harald Welte <laforge@osmocom.org>
+ * (C) 2022-2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * Author: Daniel Willmann <dwillmann@sysmocom.de>
+ *
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  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 2 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.
+ */
+
+#include "../config.h"
+#if defined(__linux__)
+
+#include <errno.h>
+#include <stdio.h>
+#include <talloc.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/socket.h>
+
+#include <osmocom/core/osmo_io.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+
+#include "osmo_io_internal.h"
+
+static void iofd_poll_ofd_cb_recvmsg_sendmsg(struct osmo_fd *ofd, unsigned int what)
+{
+	struct osmo_io_fd *iofd = ofd->data;
+	struct msgb *msg;
+	int rc, flags = 0;
+
+	if (what & OSMO_FD_READ) {
+		struct iofd_msghdr hdr;
+		msg = iofd_msgb_pending_or_alloc(iofd);
+		if (!msg) {
+			LOGP(DLIO, LOGL_ERROR, "iofd(%s): Could not get msgb for reading\n", iofd->name);
+			OSMO_ASSERT(0);
+		}
+
+		hdr.msg = msg;
+		hdr.iov[0].iov_base = msgb_data(msg);
+		hdr.iov[0].iov_len = msgb_tailroom(msg);
+		hdr.hdr.msg_iov = &hdr.iov[0];
+		hdr.hdr.msg_iovlen = 1;
+		hdr.hdr.msg_name = &hdr.osa.u.sa;
+		hdr.hdr.msg_namelen = osmo_sockaddr_size(&hdr.osa);
+
+		rc = recvmsg(ofd->fd, &hdr.hdr, flags);
+		if (rc > 0)
+			msgb_put(msg, rc);
+
+		switch (iofd->mode) {
+		case OSMO_IO_FD_MODE_READ_WRITE:
+			iofd_handle_segmented_read(iofd, msg, rc);
+			break;
+		case OSMO_IO_FD_MODE_RECVFROM_SENDTO:
+			iofd->io_ops.recvfrom_cb(iofd, rc, msg, &hdr.osa);
+			break;
+		case OSMO_IO_FD_MODE_SCTP_RECVMSG_SENDMSG:
+			/* TODO Implement */
+			OSMO_ASSERT(false);
+			break;
+		}
+	}
+
+	if (iofd->closed)
+		return;
+
+	if (what & OSMO_FD_WRITE) {
+		struct iofd_msghdr *msghdr = iofd_txqueue_dequeue(iofd);
+		if (msghdr) {
+			msg = msghdr->msg;
+
+			rc = sendmsg(ofd->fd, &msghdr->hdr, msghdr->flags);
+			if (rc > 0 && rc < msgb_length(msg)) {
+				msgb_pull(msg, rc);
+				iofd_txqueue_enqueue_front(iofd, msghdr);
+				return;
+			}
+
+			switch (iofd->mode) {
+			case OSMO_IO_FD_MODE_READ_WRITE:
+				iofd->io_ops.write_cb(iofd, rc, msg);
+				break;
+			case OSMO_IO_FD_MODE_RECVFROM_SENDTO:
+				iofd->io_ops.sendto_cb(iofd, rc, msg, &msghdr->osa);
+				break;
+			case OSMO_IO_FD_MODE_SCTP_RECVMSG_SENDMSG:
+				OSMO_ASSERT(false);
+				break;
+			}
+
+			talloc_free(msghdr);
+			msgb_free(msg);
+		}
+	}
+}
+
+static int iofd_poll_ofd_cb_dispatch(struct osmo_fd *ofd, unsigned int what)
+{
+	struct osmo_io_fd *iofd = ofd->data;
+
+	iofd->in_callback = true;
+	iofd_poll_ofd_cb_recvmsg_sendmsg(ofd, what);
+	iofd->in_callback = false;
+
+	if (iofd->to_free) {
+		talloc_free(iofd);
+		return 0;
+	}
+
+	return 0;
+}
+
+int iofd_poll_register(struct osmo_io_fd *iofd)
+{
+	struct osmo_fd *ofd = &iofd->u.poll.ofd;
+	osmo_fd_setup(ofd, iofd->fd, 0, &iofd_poll_ofd_cb_dispatch, iofd, 0);
+	return osmo_fd_register(ofd);
+}
+
+int iofd_poll_unregister(struct osmo_io_fd *iofd)
+{
+	struct osmo_fd *ofd = &iofd->u.poll.ofd;
+	osmo_fd_unregister(ofd);
+
+	return 0;
+}
+
+int iofd_poll_close(struct osmo_io_fd *iofd)
+{
+	osmo_fd_close(&iofd->u.poll.ofd);
+
+	return 0;
+}
+
+void iofd_poll_read_enable(struct osmo_io_fd *iofd)
+{
+	osmo_fd_read_enable(&iofd->u.poll.ofd);
+}
+
+void iofd_poll_read_disable(struct osmo_io_fd *iofd)
+{
+	osmo_fd_read_disable(&iofd->u.poll.ofd);
+}
+
+void iofd_poll_write_enable(struct osmo_io_fd *iofd)
+{
+	osmo_fd_write_enable(&iofd->u.poll.ofd);
+}
+
+void iofd_poll_write_disable(struct osmo_io_fd *iofd)
+{
+	osmo_fd_write_disable(&iofd->u.poll.ofd);
+}
+
+const struct iofd_backend_ops iofd_poll_ops = {
+	.register_fd = iofd_poll_register,
+	.unregister_fd = iofd_poll_unregister,
+	.close = iofd_poll_close,
+	.write_enable = iofd_poll_write_enable,
+	.write_disable = iofd_poll_write_disable,
+	.read_enable = iofd_poll_read_enable,
+	.read_disable = iofd_poll_read_disable,
+};
+
+#endif /* defined(__linux__) */