Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/libfreerdp/locale/keyboard_x11.c

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+/**
+ * FreeRDP: A Remote Desktop Protocol Implementation
+ * X11 Keyboard Mapping
+ *
+ * Copyright 2009-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
+ * Copyright 2023 Bernhard Miklautz <bernhard.miklautz@thincast.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string.h>
+
+#include <X11/X.h>
+#include <X11/Xatom.h>
+#include <X11/Xlib.h>
+
+#include "liblocale.h"
+#include "keyboard_x11.h"
+#include "xkb_layout_ids.h"
+
+static BOOL parse_xkb_rule_names(char* xkb_rule, unsigned long num_bytes, char** layout,
+                                 char** variant)
+{
+	/* Sample output for "Canadian Multilingual Standard"
+	 *
+	 * _XKB_RULES_NAMES_BACKUP(STRING) = "xorg", "pc105", "ca", "multi", "magic"
+	 *
+	 *  Format: "rules", "model", "layout", "variant", "options"
+	 *
+	 * Where "xorg" is the set of rules
+	 * "pc105" the keyboard model
+	 * "ca" the keyboard layout(s) (can also be something like 'us,uk')
+	 * "multi" the keyboard layout variant(s)  (in the examples, “,winkeys” - which means first
+	 *         layout uses some “default” variant and second uses “winkeys” variant)
+	 * "magic" - configuration option (in the examples,
+	 * “eurosign:e,lv3:ralt_switch,grp:rctrl_toggle”
+	 *         - three options)
+	 */
+	for (size_t i = 0, index = 0; i < num_bytes; i++, index++)
+	{
+		char* ptr = xkb_rule + i;
+		i += strnlen(ptr, num_bytes - i);
+
+		switch (index)
+		{
+			case 0: // rules
+				break;
+			case 1: // model
+				break;
+			case 2: // layout
+			{
+				/* If multiple languages are present we just take the first one */
+				char* delimiter = strchr(ptr, ',');
+				if (delimiter)
+					*delimiter = '\0';
+				*layout = ptr;
+				break;
+			}
+			case 3: // variant
+			{
+				/* If multiple variants are present we just take the first one */
+				char* delimiter = strchr(ptr, ',');
+				if (delimiter)
+					*delimiter = '\0';
+				*variant = ptr;
+			}
+			break;
+			case 4: // option
+				break;
+			default:
+				break;
+		}
+	}
+	return TRUE;
+}
+
+static DWORD kbd_layout_id_from_x_property(Display* display, Window root, char* property_name)
+{
+	char* layout = nullptr;
+	char* variant = nullptr;
+	char* rule = nullptr;
+	Atom type = None;
+	int item_size = 0;
+	unsigned long items = 0;
+	unsigned long unread_items = 0;
+	DWORD layout_id = 0;
+
+	Atom property = XInternAtom(display, property_name, False);
+	if (property == None)
+		return 0;
+
+	if (XGetWindowProperty(display, root, property, 0, 1024, False, XA_STRING, &type, &item_size,
+	                       &items, &unread_items, (unsigned char**)&rule) != Success)
+		return 0;
+
+	if (type != XA_STRING || item_size != 8 || unread_items != 0)
+	{
+		XFree(rule);
+		return 0;
+	}
+
+	parse_xkb_rule_names(rule, items, &layout, &variant);
+
+	DEBUG_KBD("%s layout: %s, variant: %s", property_name, layout, variant);
+	layout_id = find_keyboard_layout_in_xorg_rules(layout, variant);
+
+	XFree(rule);
+
+	return layout_id;
+}
+
+int freerdp_detect_keyboard_layout_from_xkb(DWORD* keyboardLayoutId)
+{
+	Display* display = XOpenDisplay(nullptr);
+
+	if (!display)
+		return 0;
+
+	Window root = DefaultRootWindow(display);
+	if (!root)
+		return 0;
+
+	/* We start by looking for _XKB_RULES_NAMES_BACKUP which appears to be used by libxklavier */
+	DWORD id = kbd_layout_id_from_x_property(display, root, "_XKB_RULES_NAMES_BACKUP");
+
+	if (0 == id)
+		id = kbd_layout_id_from_x_property(display, root, "_XKB_RULES_NAMES");
+
+	if (0 != id)
+		*keyboardLayoutId = id;
+
+	XCloseDisplay(display);
+	return (int)id;
+}