From a02f47f140e496368f5561292a3d1e4cdd720167 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miroslav=20=C5=A0ediv=C3=BD?= <sedivy.miro@gmail.com>
Date: Sat, 14 Jan 2023 21:15:52 +0100
Subject: [PATCH] update xorg bindings.

---
 docs/changelog.md                   |   1 +
 server/internal/desktop/xorg/xorg.c | 121 ++++++++++++++++++++++++----
 server/internal/desktop/xorg/xorg.h |   5 ++
 3 files changed, 111 insertions(+), 16 deletions(-)

diff --git a/docs/changelog.md b/docs/changelog.md
index e8a632d..b995b20 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -5,6 +5,7 @@
 ### Bugs
 - Fixed TCP mux occasional freeze by adding write buffer to it.
 - Fixed stereo problem in chromium-based browsers, where it was only as mono by adding `stereo=1` to opus SDP to clients answer.
+- Fixed keysym mapping for unknown keycodes, which was causing some key combinations to not work on some keyboards.
 
 ## [n.eko v2.7](https://github.com/m1k1o/neko/releases/tag/v2.7)
 
diff --git a/server/internal/desktop/xorg/xorg.c b/server/internal/desktop/xorg/xorg.c
index bc545c4..358d854 100644
--- a/server/internal/desktop/xorg/xorg.c
+++ b/server/internal/desktop/xorg/xorg.c
@@ -71,6 +71,7 @@ void XButton(unsigned int button, int down) {
 
 static xkeyentry_t *xKeysHead = NULL;
 
+// add keycode->keysym mapping to list
 void XKeyEntryAdd(KeySym keysym, KeyCode keycode) {
   xkeyentry_t *entry = (xkeyentry_t *) malloc(sizeof(xkeyentry_t));
   if (entry == NULL)
@@ -82,6 +83,7 @@ void XKeyEntryAdd(KeySym keysym, KeyCode keycode) {
   xKeysHead = entry;
 }
 
+// get keycode for keysym from list
 KeyCode XKeyEntryGet(KeySym keysym) {
   xkeyentry_t *prev = NULL;
   xkeyentry_t *curr = xKeysHead;
@@ -147,6 +149,100 @@ KeyCode XkbKeysymToKeycode(Display* dpy, KeySym keysym) {
   return keycode;
 }
 
+static xkeycode_t *xFreeKeycodesHead = NULL;
+int xNumcodes = 0;
+
+void XFreeKeycodesInit(Display* dpy) {
+  if (xFreeKeycodesHead != NULL)
+    return;
+
+  KeyCode keycode;
+  KeySym *keysyms;
+  int min, max, numcodes;
+
+  // get full keyboard mapping
+  XDisplayKeycodes(dpy, &min, &max);
+  keysyms = XGetKeyboardMapping(dpy, min, max-min, &numcodes);
+  xNumcodes = numcodes;
+
+  // loop through all keycodes
+  xkeycode_t *last = NULL;
+  for (int i = min; i <= max; ++i) {
+    // check if keycode is empty
+    int isEmpty = 1;
+    for (int j = 0; j < numcodes; ++j) {
+      int symindex = ((i - min) * numcodes) + j;
+      if (keysyms[symindex] != 0) {
+        isEmpty = 0;
+        break;
+      }
+    }
+    if (!isEmpty) continue;
+
+    xkeycode_t *entry = (xkeycode_t *) malloc(sizeof(xkeycode_t));
+    if (entry == NULL) return;
+
+    entry->keycode = i;
+    if (last == NULL) {
+      xFreeKeycodesHead = entry;
+    } else {
+      last->next = entry;
+    } 
+    last = entry;
+  }
+
+  // no free keycodes, pick last two keycodes anyway
+  if (last == NULL) {
+    xkeycode_t *entry1 = (xkeycode_t *) malloc(sizeof(xkeycode_t));
+    if (entry1 == NULL) return;
+    entry1->keycode = max-1;
+
+    xkeycode_t *entry2 = (xkeycode_t *) malloc(sizeof(xkeycode_t));
+    if (entry2 == NULL) return;
+    entry2->keycode = max-2;
+
+    xFreeKeycodesHead = entry1;
+    entry1->next = entry2;
+    last = entry2;
+  }
+
+  // make as circular list
+  last->next = xFreeKeycodesHead;
+
+  XFree(keysyms);
+}
+
+// get free keycode from list
+KeyCode XFreeKeycodeGet() {
+  if (xFreeKeycodesHead == NULL)
+    return 0;
+
+  // move head to next entry
+  xkeycode_t *entry = xFreeKeycodesHead;
+  xFreeKeycodesHead = entry->next;
+
+  return entry->keycode;
+}
+
+// map keysym to new keycode
+KeyCode XKeysymMapNew(Display* dpy, KeySym keysym) {
+  // initialize free keycodes list
+  if (xFreeKeycodesHead == NULL) {
+    XFreeKeycodesInit(dpy);
+  }
+
+  KeyCode keycode = XFreeKeycodeGet();
+
+  // no free keycodes, cannot map keysym
+  if (keycode != 0) {
+    KeySym keysym_list[xNumcodes];
+    for(int i=0;i<xNumcodes;i++) keysym_list[i] = keysym;
+    XChangeKeyboardMapping(dpy, keycode, xNumcodes, keysym_list, 1);
+  }
+
+  return keycode;
+}
+
 void XKey(KeySym keysym, int down) {
   if (keysym == 0)
     return;
@@ -157,20 +253,13 @@ void XKey(KeySym keysym, int down) {
   if (!down)
     keycode = XKeyEntryGet(keysym);
 
+  // Try to get keysyms from existing keycodes
   if (keycode == 0)
     keycode = XkbKeysymToKeycode(display, keysym);
 
   // Map non-existing keysyms to new keycodes
-  if (keycode == 0) {
-    int min, max, numcodes;
-    XDisplayKeycodes(display, &min, &max);
-    XGetKeyboardMapping(display, min, max-min, &numcodes);
-
-    keycode = (max-min+1)*numcodes;
-    KeySym keysym_list[numcodes];
-    for(int i=0;i<numcodes;i++) keysym_list[i] = keysym;
-    XChangeKeyboardMapping(display, keycode, numcodes, keysym_list, 1);
-  }
+  if (keycode == 0)
+    keycode = XKeysymMapNew(display, keysym);
 
   if (down)
     XKeyEntryAdd(keysym, keycode);
@@ -250,14 +339,14 @@ char *XGetScreenshot(int *w, int *h) {
   *h = height;
   char *pixels = (char *)malloc(width * height * 3);
 
-	for (int row = 0; row < height; row++) {
-		for (int col = 0; col < width; col++) {
-			int pos = ((row * width) + col) * 3;
+  for (int row = 0; row < height; row++) {
+    for (int col = 0; col < width; col++) {
+      int pos = ((row * width) + col) * 3;
       unsigned long pixel = XGetPixel(ximage, col, row);
 
-			pixels[pos]   = (pixel & ximage->red_mask)   >> 16;
-			pixels[pos+1] = (pixel & ximage->green_mask) >> 8;
-			pixels[pos+2] =  pixel & ximage->blue_mask;
+      pixels[pos]   = (pixel & ximage->red_mask)   >> 16;
+      pixels[pos+1] = (pixel & ximage->green_mask) >> 8;
+      pixels[pos+2] =  pixel & ximage->blue_mask;
     }
   }
 
diff --git a/server/internal/desktop/xorg/xorg.h b/server/internal/desktop/xorg/xorg.h
index f5ebd39..59a2b2c 100644
--- a/server/internal/desktop/xorg/xorg.h
+++ b/server/internal/desktop/xorg/xorg.h
@@ -26,6 +26,11 @@ typedef struct xkeyentry_t {
   struct xkeyentry_t *next;
 } xkeyentry_t;
 
+typedef struct xkeycode_t {
+  KeyCode keycode;
+  struct xkeycode_t *next;
+} xkeycode_t;
+
 static void XKeyEntryAdd(KeySym keysym, KeyCode keycode);
 static KeyCode XKeyEntryGet(KeySym keysym);
 static KeyCode XkbKeysymToKeycode(Display *dpy, KeySym keysym);