From 6a61bf6d0ce7c6da80ebd2f3fcd8e8ba2cb3c4e9 Mon Sep 17 00:00:00 2001
From: sleeptightAnsiC <91839286+sleeptightAnsiC@users.noreply.github.com>
Date: Tue, 18 Feb 2025 12:37:53 +0100
Subject: [PATCH] [rcore_desktop_glfw.c] fix: make sure that GLFW uses
 RL_*alloc macros

Raylib allows for providing custom allocators via macros.
GLFW supports this too, but via function pointers.

Make sure that GLFW uses those Raylib macros, by wrapping them in
function calls and setting them up inside of InitPlatform().
This is possible because of glfwInitAllocator() and GLFWallocator.

Fixes: https://github.com/raysan5/raylib/issues/4776
Relates-to: https://github.com/raysan5/raylib/issues/4751
---
 src/platforms/rcore_desktop_glfw.c | 40 ++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/src/platforms/rcore_desktop_glfw.c b/src/platforms/rcore_desktop_glfw.c
index 279f8c193..90b725ddb 100644
--- a/src/platforms/rcore_desktop_glfw.c
+++ b/src/platforms/rcore_desktop_glfw.c
@@ -86,6 +86,8 @@
     #include "GLFW/glfw3native.h"       // Required for: glfwGetCocoaWindow()
 #endif
 
+#include <stddef.h>  // Required for: size_t
+
 //----------------------------------------------------------------------------------
 // Types and Structures Definition
 //----------------------------------------------------------------------------------
@@ -127,6 +129,11 @@ static void MouseScrollCallback(GLFWwindow *window, double xoffset, double yoffs
 static void CursorEnterCallback(GLFWwindow *window, int enter);                            // GLFW3 Cursor Enter Callback, cursor enters client area
 static void JoystickCallback(int jid, int event);                                           // GLFW3 Joystick Connected/Disconnected Callback
 
+// Wrappers used by glfwInitAllocator
+static void* AllocateWrapper(size_t size, void* user);                                     // GLFW3 GLFWallocatefun, wrapps around RL_MALLOC macro
+static void* ReallocateWrapper(void* block, size_t size, void* user);                      // GLFW3 GLFWreallocatefun, wrapps around RL_MALLOC macro
+static void DeallocateWrapper(void* block, void* user);                                    // GLFW3 GLFWdeallocatefun, wraps around RL_FREE macro
+
 //----------------------------------------------------------------------------------
 // Module Functions Declaration
 //----------------------------------------------------------------------------------
@@ -1287,21 +1294,38 @@ static void SetDimensionsFromMonitor(GLFWmonitor *monitor)
   if (CORE.Window.screen.height == 0) CORE.Window.screen.height = CORE.Window.display.height;
 }
 
+// Function wrappers around RL_*alloc macros, used by glfwInitAllocator() inside of InitPlatform()
+// We need to provide these because GLFWallocator expects function pointers with specific signatures.
+// Similar wrappers exist in utils.c but we cannot reuse them here due to declaration mismatch.
+// https://www.glfw.org/docs/latest/intro_guide.html#init_allocator
+static void* AllocateWrapper(size_t size, void* user)
+{
+    (void)user;
+    return RL_MALLOC(size);
+}
+static void* ReallocateWrapper(void* block, size_t size, void* user)
+{
+    (void)user;
+    return RL_REALLOC(block, size);
+}
+static void DeallocateWrapper(void* block, void* user)
+{
+    (void)user;
+    RL_FREE(block);
+}
+
 // Initialize platform: graphics, inputs and more
 int InitPlatform(void)
 {
     glfwSetErrorCallback(ErrorCallback);
-/*
-    // TODO: Setup GLFW custom allocators to match raylib ones
+
     const GLFWallocator allocator = {
-        .allocate = MemAlloc,
-        .deallocate = MemFree,
-        .reallocate = MemRealloc,
-        .user = NULL
+        .allocate = AllocateWrapper,
+        .deallocate = DeallocateWrapper,
+        .reallocate = ReallocateWrapper,
+        .user = NULL, // RL_*ALLOC macros are not capable of handling user-provided data
     };
-
     glfwInitAllocator(&allocator);
-*/
 
 #if defined(__APPLE__)
     glfwInitHint(GLFW_COCOA_CHDIR_RESOURCES, GLFW_FALSE);