From 2d3ce6eaae71020826d0bcd1f16e78401bfe4c7d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Mon, 4 Oct 2021 20:32:32 +0200
Subject: [PATCH] Make native access functions verify context API

The native access functions for context handles did not verify that the
context had been created with the same API the function was for.

This makes these functions emit GLFW_NO_WINDOW_CONTEXT on API mismatch.

(cherry picked from commit cca9008db29f697dd3dc6d23dc149c1b3d29aa00)
---
 README.md            |  1 +
 src/egl_context.c    |  4 ++--
 src/glx_context.c    |  4 ++--
 src/nsgl_context.m   |  2 +-
 src/osmesa_context.c | 14 +++++++++++++-
 src/wgl_context.c    |  2 +-
 6 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 8e6091dc..9f496c10 100644
--- a/README.md
+++ b/README.md
@@ -121,6 +121,7 @@ information on what to include when reporting a bug.
  - Bugfix: Buffers were swapped at creation on single-buffered windows (#1873)
  - Bugfix: Gamepad mapping updates could spam `GLFW_INVALID_VALUE` due to
    incompatible controllers sharing hardware ID (#1763)
+ - Bugfix: Native access functions for context handles did not check that the API matched
  - [Win32] Bugfix: `USE_MSVC_RUNTIME_LIBRARY_DLL` had no effect on CMake 3.15 or
    later (#1783,#1796)
  - [Win32] Bugfix: Compilation with LLVM for Windows failed (#1807,#1824,#1874)
diff --git a/src/egl_context.c b/src/egl_context.c
index 8feb211d..0d63192e 100644
--- a/src/egl_context.c
+++ b/src/egl_context.c
@@ -765,7 +765,7 @@ GLFWAPI EGLContext glfwGetEGLContext(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(EGL_NO_CONTEXT);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_EGL_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return EGL_NO_CONTEXT;
@@ -779,7 +779,7 @@ GLFWAPI EGLSurface glfwGetEGLSurface(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(EGL_NO_SURFACE);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_EGL_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return EGL_NO_SURFACE;
diff --git a/src/glx_context.c b/src/glx_context.c
index ec1adc75..db563baa 100644
--- a/src/glx_context.c
+++ b/src/glx_context.c
@@ -674,7 +674,7 @@ GLFWAPI GLXContext glfwGetGLXContext(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_NATIVE_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return NULL;
@@ -688,7 +688,7 @@ GLFWAPI GLXWindow glfwGetGLXWindow(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_NATIVE_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return None;
diff --git a/src/nsgl_context.m b/src/nsgl_context.m
index 10286849..a27b9ecc 100644
--- a/src/nsgl_context.m
+++ b/src/nsgl_context.m
@@ -365,7 +365,7 @@ GLFWAPI id glfwGetNSGLContext(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(nil);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_NATIVE_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return nil;
diff --git a/src/osmesa_context.c b/src/osmesa_context.c
index c2fa49d4..975e536b 100644
--- a/src/osmesa_context.c
+++ b/src/osmesa_context.c
@@ -302,6 +302,12 @@ GLFWAPI int glfwGetOSMesaColorBuffer(GLFWwindow* handle, int* width,
 
     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);
 
+    if (window->context.client != GLFW_OSMESA_CONTEXT_API)
+    {
+        _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
+        return GLFW_FALSE;
+    }
+
     if (!OSMesaGetColorBuffer(window->context.osmesa.handle,
                               &mesaWidth, &mesaHeight,
                               &mesaFormat, &mesaBuffer))
@@ -335,6 +341,12 @@ GLFWAPI int glfwGetOSMesaDepthBuffer(GLFWwindow* handle,
 
     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);
 
+    if (window->context.client != GLFW_OSMESA_CONTEXT_API)
+    {
+        _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
+        return GLFW_FALSE;
+    }
+
     if (!OSMesaGetDepthBuffer(window->context.osmesa.handle,
                               &mesaWidth, &mesaHeight,
                               &mesaBytes, &mesaBuffer))
@@ -361,7 +373,7 @@ GLFWAPI OSMesaContext glfwGetOSMesaContext(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_OSMESA_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return NULL;
diff --git a/src/wgl_context.c b/src/wgl_context.c
index a76795d8..451fef63 100644
--- a/src/wgl_context.c
+++ b/src/wgl_context.c
@@ -787,7 +787,7 @@ GLFWAPI HGLRC glfwGetWGLContext(GLFWwindow* handle)
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
-    if (window->context.client == GLFW_NO_API)
+    if (window->context.client != GLFW_NATIVE_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return NULL;