[Mesa-dev] [PATCH 2/2] egl/glvnd: correctly report errors when vendor cannot be found

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

If the user provides an invalid display or device the ToVendor lookup
will fail.

In this case, the local [Mesa vendor] error code will be set. Thus on
sequential eglGetError(), the error will be EGL_SUCCESS.

To be more specific, GLVND remembers the last vendor and calls back
into it's eglGetError, although there's no guarantee to ever have had
one.

Piglit: tests/egl/spec/egl_ext_device_query
Fixes: ce562f9e3fa ("EGL: Implement the libglvnd interface for EGL (v3)")
Cc: Kyle Brenneman <kbrenneman at nvidia.com>
Cc: Eric Engestrom <eric at engestrom.ch>
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
 src/egl/main/egldispatchstubs.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/egl/main/egldispatchstubs.c b/src/egl/main/egldispatchstubs.c
index bfc3195c779..e39fd6197a6 100644
--- a/src/egl/main/egldispatchstubs.c
+++ b/src/egl/main/egldispatchstubs.c
@@ -54,9 +54,17 @@ static __eglMustCastToProperFunctionPointerType FetchVendorFunc(__EGLvendorInfo
 {
     __eglMustCastToProperFunctionPointerType func = NULL;
 
-    if (vendor != NULL) {
-        func = exports->fetchDispatchEntry(vendor, __EGL_DISPATCH_FUNC_INDICES[index]);
+    if (vendor == NULL) {
+        // XXX: How can we end here with EGL_SUCCESS?
+        if (errorCode != EGL_SUCCESS) {
+            // Since we have no vendor, the follow-up eglGetError() call will
+            // end up using the GLVND error code. Set it here.
+            exports->setEGLError(errorCode);
+        }
+        return NULL;
     }
+
+    func = exports->fetchDispatchEntry(vendor, __EGL_DISPATCH_FUNC_INDICES[index]);
     if (func == NULL) {
         if (errorCode != EGL_SUCCESS) {
             _eglError(errorCode, __EGL_DISPATCH_FUNC_NAMES[index]);
-- 
2.19.1