Index: uspace/lib/clipboard/src/clipboard.c
===================================================================
--- uspace/lib/clipboard/src/clipboard.c	(revision dc5c303e2b29ccbf0ee833267061709da23d9de6)
+++ uspace/lib/clipboard/src/clipboard.c	(revision dc5c303e2b29ccbf0ee833267061709da23d9de6)
@@ -0,0 +1,210 @@
+/*
+ * Copyright (c) 2023 Jiri Svoboda
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libclipboard
+ * @{
+ */
+/** @file
+ * @brief System clipboard API.
+ *
+ * The clipboard data is managed by the clipboard service and it is shared by
+ * the entire system.
+ *
+ */
+
+#include <async.h>
+#include <clipboard.h>
+#include <errno.h>
+#include <fibril_synch.h>
+#include <ipc/clipboard.h>
+#include <ipc/services.h>
+#include <loc.h>
+#include <stdlib.h>
+#include <str.h>
+
+static FIBRIL_MUTEX_INITIALIZE(clip_mutex);
+static async_sess_t *clip_sess = NULL;
+
+/** Start an async exchange on the clipboard session.
+ *
+ * @return New exchange.
+ *
+ */
+static async_exch_t *clip_exchange_begin(void)
+{
+	service_id_t sid;
+	errno_t rc;
+
+	fibril_mutex_lock(&clip_mutex);
+
+	while (clip_sess == NULL) {
+		rc = loc_service_get_id(SERVICE_NAME_CLIPBOARD, &sid,
+		    IPC_FLAG_BLOCKING);
+		if (rc != EOK)
+			continue;
+
+		clip_sess = loc_service_connect(sid, INTERFACE_CLIPBOARD,
+		    IPC_FLAG_BLOCKING);
+	}
+
+	fibril_mutex_unlock(&clip_mutex);
+
+	return async_exchange_begin(clip_sess);
+}
+
+/** Finish an async exchange on the clipboard session.
+ *
+ * @param exch Exchange to be finished.
+ *
+ */
+static void clip_exchange_end(async_exch_t *exch)
+{
+	async_exchange_end(exch);
+}
+
+/** Copy string to clipboard.
+ *
+ * Sets the clipboard contents to @a str. Passing an empty string or NULL
+ * makes the clipboard empty.
+ *
+ * @param str String to put to clipboard or NULL.
+ *
+ * @return Zero on success or an error code.
+ *
+ */
+errno_t clipboard_put_str(const char *str)
+{
+	size_t size = str_size(str);
+
+	if (size == 0) {
+		async_exch_t *exch = clip_exchange_begin();
+		errno_t rc = async_req_1_0(exch, CLIPBOARD_PUT_DATA,
+		    CLIPBOARD_TAG_NONE);
+		clip_exchange_end(exch);
+
+		return (errno_t) rc;
+	} else {
+		async_exch_t *exch = clip_exchange_begin();
+		aid_t req = async_send_1(exch, CLIPBOARD_PUT_DATA, CLIPBOARD_TAG_DATA,
+		    NULL);
+		errno_t rc = async_data_write_start(exch, (void *) str, size);
+		clip_exchange_end(exch);
+
+		if (rc != EOK) {
+			errno_t rc_orig;
+			async_wait_for(req, &rc_orig);
+			if (rc_orig == EOK)
+				return (errno_t) rc;
+			else
+				return (errno_t) rc_orig;
+		}
+
+		async_wait_for(req, &rc);
+
+		return (errno_t) rc;
+	}
+}
+
+/** Get a copy of clipboard contents.
+ *
+ * Returns a new string that can be deallocated with free().
+ *
+ * @param str Here pointer to the newly allocated string is stored.
+ *
+ * @return Zero on success or an error code.
+ *
+ */
+errno_t clipboard_get_str(char **str)
+{
+	/* Loop until clipboard read succesful */
+	while (true) {
+		async_exch_t *exch = clip_exchange_begin();
+
+		sysarg_t size;
+		sysarg_t tag;
+		errno_t rc = async_req_0_2(exch, CLIPBOARD_CONTENT, &size, &tag);
+
+		clip_exchange_end(exch);
+
+		if (rc != EOK)
+			return (errno_t) rc;
+
+		char *sbuf;
+
+		switch (tag) {
+		case CLIPBOARD_TAG_NONE:
+			sbuf = malloc(1);
+			if (sbuf == NULL)
+				return ENOMEM;
+
+			sbuf[0] = 0;
+			*str = sbuf;
+			return EOK;
+		case CLIPBOARD_TAG_DATA:
+			sbuf = malloc(size + 1);
+			if (sbuf == NULL)
+				return ENOMEM;
+
+			exch = clip_exchange_begin();
+			aid_t req = async_send_1(exch, CLIPBOARD_GET_DATA, tag, NULL);
+			rc = async_data_read_start(exch, (void *) sbuf, size);
+			clip_exchange_end(exch);
+
+			if ((errno_t) rc == EOVERFLOW) {
+				/*
+				 * The data in the clipboard has changed since
+				 * the last call of CLIPBOARD_CONTENT
+				 */
+				break;
+			}
+
+			if (rc != EOK) {
+				errno_t rc_orig;
+				async_wait_for(req, &rc_orig);
+				if (rc_orig == EOK)
+					return (errno_t) rc;
+				else
+					return (errno_t) rc_orig;
+			}
+
+			async_wait_for(req, &rc);
+
+			if (rc == EOK) {
+				sbuf[size] = 0;
+				*str = sbuf;
+			}
+
+			return rc;
+		default:
+			return EINVAL;
+		}
+	}
+}
+
+/** @}
+ */
