From c6eaca88cdd711109e7489cca0419466e2ee85f7 Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <info@metux.net>
Date: Tue, 25 Mar 2025 19:25:32 +0100
Subject: [PATCH] dix: reserve fixed extension opcodes for known extensions

Assign fixed opcodes for known (in-tree) extensions and add
defines for them. Other places (eg. security extensions) that
need to know those opcodes now can directly use those defines
not having to look them up at runtime.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 dix/extension.c      | 47 ++++++++++++++++++++++++++++++++++++++++++++
 dix/extension_priv.h | 40 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/dix/extension.c b/dix/extension.c
index d6d9cd39f..52bf19e64 100644
--- a/dix/extension.c
+++ b/dix/extension.c
@@ -69,8 +69,55 @@ int lastEvent = EXTENSION_EVENT_BASE;
 static int lastError = FirstExtensionError;
 static unsigned int NumExtensions = RESERVED_EXTENSIONS;
 
+static struct { const char *name; int id; } reservedExt[] = {
+    { "BIG-REQUESTS",               EXTENSION_MAJOR_BIG_REQUESTS },
+    { "Apple-WM",                   EXTENSION_MAJOR_APPLE_WM },
+    { "Apple-DRI",                  EXTENSION_MAJOR_APPLE_DRI },
+    { "Composite",                  EXTENSION_MAJOR_COMPOSITE },
+    { "DAMAGE",                     EXTENSION_MAJOR_DAMAGE },
+    { "DOUBLE-BUFFER",              EXTENSION_MAJOR_DOUBLE_BUFFER },
+    { "DPMS",                       EXTENSION_MAJOR_DPMS },
+    { "DRI2",                       EXTENSION_MAJOR_DRI2 },
+    { "DRI3",                       EXTENSION_MAJOR_DRI3 },
+    { "Generic Event Extension",    EXTENSION_MAJOR_GENERIC_EVENT },
+    { "GLX",                        EXTENSION_MAJOR_GLX },
+    { "MIT-SCREEN-SAVER",           EXTENSION_MAJOR_MIT_SCREEN_SAVER },
+    { "NAMESPACE",                  EXTENSION_MAJOR_NAMESPACE },
+    { "Present",                    EXTENSION_MAJOR_PRESENT },
+    { "RANDR",                      EXTENSION_MAJOR_RANDR },
+    { "RECORD",                     EXTENSION_MAJOR_RECORD },
+    { "RENDER",                     EXTENSION_MAJOR_RENDER },
+    { "SECURITY",                   EXTENSION_MAJOR_SECURITY },
+    { "SELinux",                    EXTENSION_MAJOR_SELINUX },
+    { "SHAPE",                      EXTENSION_MAJOR_SHAPE },
+    { "MIT-SHM",                    EXTENSION_MAJOR_SHM },
+    { "SYNC",                       EXTENSION_MAJOR_SYNC },
+    { "Windows-DRI",                EXTENSION_MAJOR_WINDOWS_DRI },
+    { "XFIXES",                     EXTENSION_MAJOR_XFIXES },
+    { "XFree86-Bigfont",            EXTENSION_MAJOR_XF86_BIGFONT },
+    { "XFree86-DGA",                EXTENSION_MAJOR_XF86_DGA },
+    { "XFree86-DRI",                EXTENSION_MAJOR_XF86_DRI },
+    { "XFree86-VidModeExtension",   EXTENSION_MAJOR_XF86_VIDMODE },
+    { "XC-MISC",                    EXTENSION_MAJOR_XC_MISC },
+    { "XInputExtension",            EXTENSION_MAJOR_XINPUT },
+    { "XINERAMA",                   EXTENSION_MAJOR_XINERAMA },
+    { "XKEYBOARD",                  EXTENSION_MAJOR_XKEYBOARD },
+    { "X-Resource",                 EXTENSION_MAJOR_XRESOURCE },
+    { "XTEST",                      EXTENSION_MAJOR_XTEST },
+    { "XVideo",                     EXTENSION_MAJOR_XVIDEO },
+    { "XVideo-MotionCompensation",  EXTENSION_MAJOR_XVMC },
+    { "XWAYLAND",                   EXTENSION_MAJOR_XWAYLAND },
+};
+
 static int checkReserved(const char* name)
 {
+    for (int i=0; i<ARRAY_SIZE(reservedExt); i++) {
+        if (strcmp(name, reservedExt[i].name) == 0) {
+            if (reservedExt[i].id < (RESERVED_EXTENSIONS + EXTENSION_BASE))
+                return reservedExt[i].id;
+            FatalError("BUG: RESERVED_EXTENSIONS too small for %d\n", reservedExt[i].id);
+        }
+    }
     return -1;
 }
 
diff --git a/dix/extension_priv.h b/dix/extension_priv.h
index b0c768485..71764ba0c 100644
--- a/dix/extension_priv.h
+++ b/dix/extension_priv.h
@@ -7,6 +7,44 @@
 
 #include "misc.h"
 
-#define RESERVED_EXTENSIONS                 2
+#define EXTENSION_MAJOR_APPLE_WM            (EXTENSION_BASE + 0)
+#define EXTENSION_MAJOR_APPLE_DRI           (EXTENSION_BASE + 1)
+#define EXTENSION_MAJOR_BIG_REQUESTS        (EXTENSION_BASE + 2)
+#define EXTENSION_MAJOR_COMPOSITE           (EXTENSION_BASE + 3)
+#define EXTENSION_MAJOR_DAMAGE              (EXTENSION_BASE + 4)
+#define EXTENSION_MAJOR_DOUBLE_BUFFER       (EXTENSION_BASE + 5)
+#define EXTENSION_MAJOR_DPMS                (EXTENSION_BASE + 6)
+#define EXTENSION_MAJOR_DRI2                (EXTENSION_BASE + 7)
+#define EXTENSION_MAJOR_DRI3                (EXTENSION_BASE + 8)
+#define EXTENSION_MAJOR_GENERIC_EVENT       (EXTENSION_BASE + 9)
+#define EXTENSION_MAJOR_GLX                 (EXTENSION_BASE + 10)
+#define EXTENSION_MAJOR_MIT_SCREEN_SAVER    (EXTENSION_BASE + 11)
+#define EXTENSION_MAJOR_NAMESPACE           (EXTENSION_BASE + 12)
+#define EXTENSION_MAJOR_PRESENT             (EXTENSION_BASE + 13)
+#define EXTENSION_MAJOR_RANDR               (EXTENSION_BASE + 14)
+#define EXTENSION_MAJOR_RECORD              (EXTENSION_BASE + 15)
+#define EXTENSION_MAJOR_RENDER              (EXTENSION_BASE + 16)
+#define EXTENSION_MAJOR_SECURITY            (EXTENSION_BASE + 17)
+#define EXTENSION_MAJOR_SELINUX             (EXTENSION_BASE + 18)
+#define EXTENSION_MAJOR_SHAPE               (EXTENSION_BASE + 19)
+#define EXTENSION_MAJOR_SHM                 (EXTENSION_BASE + 20)
+#define EXTENSION_MAJOR_SYNC                (EXTENSION_BASE + 21)
+#define EXTENSION_MAJOR_WINDOWS_DRI         (EXTENSION_BASE + 22)
+#define EXTENSION_MAJOR_XFIXES              (EXTENSION_BASE + 23)
+#define EXTENSION_MAJOR_XF86_BIGFONT        (EXTENSION_BASE + 24)
+#define EXTENSION_MAJOR_XF86_DGA            (EXTENSION_BASE + 25)
+#define EXTENSION_MAJOR_XF86_DRI            (EXTENSION_BASE + 26)
+#define EXTENSION_MAJOR_XF86_VIDMODE        (EXTENSION_BASE + 27)
+#define EXTENSION_MAJOR_XC_MISC             (EXTENSION_BASE + 28)
+#define EXTENSION_MAJOR_XINPUT              (EXTENSION_BASE + 29)
+#define EXTENSION_MAJOR_XINERAMA            (EXTENSION_BASE + 30)
+#define EXTENSION_MAJOR_XKEYBOARD           (EXTENSION_BASE + 31)
+#define EXTENSION_MAJOR_XRESOURCE           (EXTENSION_BASE + 32)
+#define EXTENSION_MAJOR_XTEST               (EXTENSION_BASE + 33)
+#define EXTENSION_MAJOR_XVIDEO              (EXTENSION_BASE + 34)
+#define EXTENSION_MAJOR_XVMC                (EXTENSION_BASE + 35)
+#define EXTENSION_MAJOR_XWAYLAND            (EXTENSION_BASE + 36)
+
+#define RESERVED_EXTENSIONS                 38
 
 #endif /* _XSERVER_EXTENSION_PRIV_H */