Files
MobileGL/MobileGL/MG_IntegrationTest/Harness/HeadlessGL.cpp
T

642 lines
28 KiB
C++

// MobileGL - MobileGL/MG_IntegrationTest/Harness/HeadlessGL.cpp
// Copyright (c) 2025-2026 MobileGL-Dev
// Licensed under the GNU Lesser General Public License v3.0:
// https://www.gnu.org/licenses/gpl-3.0.txt
// https://www.gnu.org/licenses/lgpl-3.0.txt
// SPDX-License-Identifier: LGPL-3.0-only
// End of Source File Header
#include "HeadlessGL.h"
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ostream>
#include <sstream>
// MobileGL's own headers, in the order MobileGL/Includes.h uses them: GL/gl.h
// first, then glcorearb.h for the 3.x+ entry points. This binary links
// MobileGL_s, so every gl*/egl* below binds to MobileGL's implementation, not
// to a system loader.
#ifdef GLAPI
#undef GLAPI
#endif
#include <EGL/egl.h>
#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>
#include <GL/glcorearb.h>
#undef GL_GLEXT_PROTOTYPES
// The pre-flight below runs the whole EGL bring-up in a forked child, which is
// the only construction that is actually predictive here: MobileGL ABORTS
// (MOBILEGL_ASSERT -> SIGTRAP) rather than returning an error on an unusable
// platform, so nothing the parent can call in-process is allowed to be wrong.
#if !defined(_WIN32) && !defined(__APPLE__) && __has_include(<sys/wait.h>)
#define MGITEST_HAVE_FORK_PREFLIGHT 1
#include <csignal>
#include <ctime>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#else
#define MGITEST_HAVE_FORK_PREFLIGHT 0
#endif
namespace MGITest {
namespace {
// Small enough that a readback is cheap, big enough that "top third" and
// "bottom third" are unambiguous. Non-square on purpose: a transposing
// bug cannot hide behind a square.
constexpr int kSurfaceWidth = 128;
constexpr int kSurfaceHeight = 96;
std::string EnvOr(const char* name, const char* fallback) {
const char* value = std::getenv(name);
return (value != nullptr && value[0] != '\0') ? std::string(value) : std::string(fallback);
}
// A skip reason is only useful if it says which call failed AND why, so
// every bring-up step reports the EGL error it left behind.
std::string WithEglError(const char* what) {
std::ostringstream out;
out << what << " (eglGetError=0x" << std::hex << eglGetError() << ")";
return out.str();
}
// The EGL objects one bring-up produces.
struct EglBringUp {
void* display = nullptr;
void* surface = nullptr;
void* context = nullptr;
std::string renderer;
};
// The harness is headless BY CONSTRUCTION, on every machine: it must never
// reach a window system, not even where one happens to be running. This is
// not a CI accommodation - it is what keeps a developer's run and a CI run
// the same run. The lane was wired up green on a workstation and immediately
// died on the runner precisely because the workstation had a DISPLAY (WSLg)
// and took Mesa's x11 platform, while the runner has none; that divergence
// is the bug, and pinning the platform here is the fix for it.
//
// Mesa selects its EGL platform from EGL_PLATFORM at loader time, so this
// has to run before the first EGL call in the process (see EnsureHeadless
// callers). surfaceless is the platform with no window-system dependency at
// all; the surface this file then creates is still a pbuffer, which every
// platform supports and which the amendment to this rule requires as the
// fallback shape. DISPLAY/WAYLAND_DISPLAY are cleared as well so that a
// driver that consults them directly cannot reintroduce the dependency
// behind EGL's back. Desktop-only file: MG_IntegrationTest never builds
// for Android, so no device path is affected.
void EnsureHeadlessPlatform() {
#if defined(__linux__) && !defined(__ANDROID__)
static bool done = false;
if (done) {
return;
}
done = true;
// An explicit EGL_PLATFORM from the operator still wins: pinning a
// platform is exactly how someone reproduces a platform-specific bug.
if (std::getenv("EGL_PLATFORM") == nullptr) {
setenv("EGL_PLATFORM", "surfaceless", 1);
}
unsetenv("DISPLAY");
unsetenv("WAYLAND_DISPLAY");
#endif
}
// THE bring-up, in one function so the pre-flight child and the parent run
// literally the same sequence - a pre-flight that tests something narrower
// than what the parent will do is exactly the kind of "predictive" check
// that is not.
//
// Returns 0 on success, or the 1-based index of the step that failed, and
// fills outReason either way.
int RunEglBringUp(EglBringUp& out, std::string& outReason) {
// Belt and braces: the pre-flight child and the parent both enter here,
// and neither may be the first to touch EGL without this having run.
EnsureHeadlessPlatform();
EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
if (display == EGL_NO_DISPLAY) {
outReason = WithEglError("eglGetDisplay(EGL_DEFAULT_DISPLAY) returned EGL_NO_DISPLAY");
return 1;
}
EGLint major = 0, minor = 0;
if (eglInitialize(display, &major, &minor) != EGL_TRUE) {
outReason = WithEglError("eglInitialize failed: no usable display/driver on this machine");
return 2;
}
if (eglBindAPI(EGL_OPENGL_API) != EGL_TRUE) {
outReason = WithEglError("eglBindAPI(EGL_OPENGL_API) failed");
return 3;
}
const EGLint configAttribs[] = {EGL_SURFACE_TYPE,
EGL_PBUFFER_BIT,
EGL_RED_SIZE,
8,
EGL_GREEN_SIZE,
8,
EGL_BLUE_SIZE,
8,
EGL_ALPHA_SIZE,
8,
EGL_DEPTH_SIZE,
24,
EGL_RENDERABLE_TYPE,
EGL_OPENGL_BIT,
EGL_NONE};
EGLConfig config = nullptr;
EGLint configCount = 0;
if (eglChooseConfig(display, configAttribs, &config, 1, &configCount) != EGL_TRUE || configCount < 1) {
outReason = WithEglError("eglChooseConfig found no pbuffer-capable RGBA8/D24 config");
return 4;
}
const EGLint contextAttribs[] = {EGL_CONTEXT_MAJOR_VERSION, 3, EGL_CONTEXT_MINOR_VERSION, 3, EGL_NONE};
EGLContext context = eglCreateContext(display, config, EGL_NO_CONTEXT, contextAttribs);
if (context == EGL_NO_CONTEXT) {
context = eglCreateContext(display, config, EGL_NO_CONTEXT, nullptr);
}
if (context == EGL_NO_CONTEXT) {
outReason = WithEglError("eglCreateContext failed: no desktop-GL context available");
return 5;
}
const EGLint pbufferAttribs[] = {EGL_WIDTH, kSurfaceWidth, EGL_HEIGHT, kSurfaceHeight, EGL_NONE};
EGLSurface surface = eglCreatePbufferSurface(display, config, pbufferAttribs);
if (surface == EGL_NO_SURFACE) {
outReason = WithEglError("eglCreatePbufferSurface failed");
return 6;
}
// The step that brings the whole backend up (DirectVulkan creates its
// instance, device and surface in here) and therefore the step that
// aborts instead of returning an error on an unusable platform.
if (eglMakeCurrent(display, surface, surface, context) != EGL_TRUE) {
outReason = WithEglError("eglMakeCurrent failed");
return 7;
}
const GLubyte* renderer = glGetString(GL_RENDERER);
if (renderer == nullptr) {
outReason = "glGetString(GL_RENDERER) returned null after eglMakeCurrent";
return 8;
}
out.display = display;
out.surface = surface;
out.context = context;
out.renderer = reinterpret_cast<const char*>(renderer);
outReason.clear();
return 0;
}
// Platform pre-flight, and the reason this module can claim to skip
// cleanly rather than merely hope to.
//
// MobileGL does not return errors when the platform is unusable - it
// ABORTS. MOBILEGL_ASSERT raises SIGTRAP, and the DirectVulkan bring-up
// asserts its way through instance, physical-device and surface creation
// inside eglMakeCurrent. So there is no in-process question the harness
// can ask that is guaranteed to be survivable, and the old form (dlopen
// the Vulkan loader, count physical devices, look for
// VK_EXT_headless_surface) was a guess at the abort conditions rather
// than a test of them: it named three of the ways bring-up can die and
// was silent about every other one, including every DirectGLES one.
//
// What is actually predictive is to run the bring-up itself somewhere a
// SIGTRAP is a datum instead of a crash. fork() gives exactly that: the
// child performs the identical sequence and _exit(0)s on success, and
// ANY non-zero exit or ANY signal in the parent's waitpid() means "this
// platform is unusable" - whatever the reason, including reasons nobody
// has thought of. Only then does the parent do the real bring-up.
//
// Returns an empty string when the platform survived a full bring-up.
std::string PreflightBringUp() {
#if !MGITEST_HAVE_FORK_PREFLIGHT
// No fork(): let the in-process bring-up speak for itself, which is
// what this module did before. Windows/macOS are not CI targets for
// the headless scenarios.
return {};
#else
int channel[2] = {-1, -1};
if (pipe(channel) != 0) {
return {}; // cannot pre-flight; fall through to the in-process attempt
}
// The child inherits our stdio buffers; flush so nothing is printed twice.
std::fflush(nullptr);
const pid_t child = fork();
if (child < 0) {
close(channel[0]);
close(channel[1]);
return {};
}
if (child == 0) {
close(channel[0]);
// No core suppression here, deliberately: when the child dies on a
// signal, the core IS the diagnosis (an rlimit that used to sit here
// made a CI-only crash undebuggable). Machines that do not want
// cores control that with the usual ulimit/core_pattern knobs.
std::fprintf(stderr, "[itest] pre-flight child: attempting a full EGL bring-up\n");
EglBringUp local;
std::string reason;
const int step = RunEglBringUp(local, reason);
if (!reason.empty()) {
const std::size_t bytes = std::min<std::size_t>(reason.size(), 480);
const ssize_t written = write(channel[1], reason.data(), bytes);
(void)written;
}
close(channel[1]);
// _exit, never exit(): every atexit handler and static destructor
// in this address space belongs to the parent's copy of the world,
// and the child is holding a live context it must not tear down.
_exit(step);
}
close(channel[1]);
// Reap first, read after: the message is bounded well below the pipe
// buffer so the child can never block writing it, and polling the exit
// status is what lets a wedged child be killed instead of hanging the
// parent on a read that will never return.
constexpr int kPreflightTimeoutMs = 30000;
int status = 0;
int waitedMs = 0;
for (;;) {
const pid_t reaped = waitpid(child, &status, WNOHANG);
if (reaped == child) break;
if (reaped < 0) {
close(channel[0]);
return "waitpid on the EGL bring-up pre-flight child failed";
}
if (waitedMs >= kPreflightTimeoutMs) {
kill(child, SIGKILL);
(void)waitpid(child, &status, 0);
close(channel[0]);
std::ostringstream out;
out << "the EGL bring-up wedged: a forked pre-flight child made no progress in "
<< kPreflightTimeoutMs / 1000 << "s and was killed";
return out.str();
}
timespec nap{0, 10 * 1000 * 1000};
nanosleep(&nap, nullptr);
waitedMs += 10;
}
std::string childSays;
char buffer[512];
for (;;) {
const ssize_t got = read(channel[0], buffer, sizeof(buffer));
if (got <= 0) break;
childSays.append(buffer, static_cast<std::size_t>(got));
}
close(channel[0]);
if (WIFSIGNALED(status)) {
const int signalNumber = WTERMSIG(status);
const char* signalName = strsignal(signalNumber);
std::ostringstream out;
out << "the EGL bring-up ABORTS on this platform: a forked pre-flight child died on signal "
<< signalNumber << " (" << (signalName != nullptr ? signalName : "?") << ")";
if (!childSays.empty()) out << " after: " << childSays;
out << ". MobileGL asserts rather than returning an error here, so the scenarios would "
"have taken the whole test binary down with them";
return out.str();
}
if (!WIFEXITED(status)) {
return "the EGL bring-up pre-flight child neither exited nor was signalled";
}
const int exitStatus = WEXITSTATUS(status);
if (exitStatus != 0) {
std::ostringstream out;
out << (childSays.empty() ? "the EGL bring-up failed" : childSays)
<< " (forked pre-flight child exit status " << exitStatus << ")";
return out.str();
}
return {};
#endif
}
} // namespace
namespace {
bool EnvFlag(const char* name) {
const char* value = std::getenv(name);
return value != nullptr && value[0] != '\0' && std::strcmp(value, "0") != 0;
}
} // namespace
bool RequireGpu() {
return EnvFlag("MOBILEGL_ITEST_REQUIRE_GPU");
}
bool RequireHardwareGpu() {
return EnvFlag("MOBILEGL_ITEST_REQUIRE_HARDWARE_GPU");
}
std::ostream& operator<<(std::ostream& os, const Rgba8& c) {
os << "rgba(" << int(c.r) << "," << int(c.g) << "," << int(c.b) << "," << int(c.a) << ")";
return os;
}
Rgba8 Image::At(int x, int y) const {
if (x < 0 || y < 0 || x >= m_width || y >= m_height) {
return Rgba8{};
}
const std::size_t index = (static_cast<std::size_t>(y) * m_width + x) * 4;
return Rgba8{m_pixels[index], m_pixels[index + 1], m_pixels[index + 2], m_pixels[index + 3]};
}
const char* Image::ColorName(int x, int y) const {
const Rgba8 c = At(x, y);
const bool r = c.r > 160, g = c.g > 160, b = c.b > 160;
const bool nr = c.r < 96, ng = c.g < 96, nb = c.b < 96;
if (nr && ng && nb) return "black";
if (r && g && b) return "white";
if (r && ng && nb) return "red";
if (nr && g && nb) return "green";
if (nr && ng && b) return "blue";
if (r && g && nb) return "yellow";
return "other";
}
std::size_t Image::ByteDiffCount(const Image& other) const {
if (m_width != other.m_width || m_height != other.m_height) {
return std::max(m_pixels.size(), other.m_pixels.size());
}
std::size_t differing = 0;
for (std::size_t i = 0; i < m_pixels.size(); ++i) {
if (m_pixels[i] != other.m_pixels[i]) ++differing;
}
return differing;
}
std::string Image::QuadrantSignature() const {
if (m_width < 2 || m_height < 2) return "<empty>";
// Quadrant CENTRES, so a one-pixel rounding difference at a quadrant edge
// never decides the answer. Order is fixed and load-bearing: bottom-left,
// bottom-right, top-left, top-right.
const int leftX = m_width / 4;
const int rightX = m_width * 3 / 4;
const int bottomY = m_height / 4;
const int topY = m_height * 3 / 4;
std::ostringstream out;
out << ColorName(leftX, bottomY) << "," << ColorName(rightX, bottomY) << "," << ColorName(leftX, topY) << ","
<< ColorName(rightX, topY);
return out.str();
}
RegionScan ScanRegion(const Image& image, int x0, int x1, int y0, int y1, const char* expectedColor) {
RegionScan scan;
x0 = std::max(x0, 0);
y0 = std::max(y0, 0);
x1 = std::min(x1, image.Width() - 1);
y1 = std::min(y1, image.Height() - 1);
for (int y = y0; y <= y1; ++y) {
for (int x = x0; x <= x1; ++x) {
++scan.total;
const char* name = image.ColorName(x, y);
if (std::strcmp(name, expectedColor) == 0) continue;
++scan.offenders;
if (scan.firstX < 0) {
scan.firstX = x;
scan.firstY = y;
scan.firstColor = image.At(x, y);
scan.firstColorName = name;
}
}
}
return scan;
}
::testing::AssertionResult RegionIsMostly(const Image& image, int x0, int x1, int y0, int y1,
const char* expectedColor, double tolerance,
const std::string& when) {
const RegionScan scan = ScanRegion(image, x0, x1, y0, y1, expectedColor);
if (scan.total == 0) {
return ::testing::AssertionFailure()
<< when << ": region x[" << x0 << "," << x1 << "] y[" << y0 << "," << y1
<< "] is empty against a " << image.Width() << "x" << image.Height() << " readback";
}
const double offendingFraction = static_cast<double>(scan.offenders) / scan.total;
if (offendingFraction <= tolerance) {
return ::testing::AssertionSuccess();
}
return ::testing::AssertionFailure()
<< when << ": region x[" << x0 << "," << x1 << "] y[" << y0 << "," << y1 << "] should be all "
<< expectedColor << ", but " << scan.offenders << " of " << scan.total << " pixels ("
<< static_cast<int>(offendingFraction * 100.0 + 0.5) << "%) are not; first offender at (" << scan.firstX
<< "," << scan.firstY << ") is " << scan.firstColorName << " " << scan.firstColor;
}
HeadlessGL& HeadlessGL::Get() {
static HeadlessGL instance;
return instance;
}
HeadlessGL::HeadlessGL() {
// Before anything else in this process can reach EGL, and in particular
// before the pre-flight forks - the child must measure the same platform
// the parent will use.
EnsureHeadlessPlatform();
m_backendName = EnvOr("MOBILEGL_BACKEND_TYPE", "<unset>");
m_usable = BringUp();
}
bool HeadlessGL::BringUp() {
// Ask a disposable copy of this process first. Only if it survived does
// the real one try - see PreflightBringUp for why nothing weaker is
// predictive against a stack that aborts instead of returning errors.
const std::string preflightProblem = PreflightBringUp();
if (!preflightProblem.empty()) {
m_skipReason = preflightProblem;
return false;
}
// Same shape as DriverBench's boot_egl(), minus the dlopen: the provider
// is this binary. A pbuffer needs no window system, but MobileGL's own
// loader still has to reach a real driver underneath - and the child
// above just proved it can.
EglBringUp brought;
std::string reason;
if (RunEglBringUp(brought, reason) != 0) {
// The pre-flight passed and the parent's identical attempt did not.
// That is a real result, not a machine without a GPU, so say so: it
// means something is different between the two attempts (a leaked
// exclusive device, an environment the child did not have).
m_skipReason = reason + " - although an identical bring-up in a forked pre-flight child succeeded";
return false;
}
m_display = brought.display;
m_surface = brought.surface;
m_context = brought.context;
m_width = kSurfaceWidth;
m_height = kSurfaceHeight;
m_renderer = std::move(brought.renderer);
return true;
}
void HeadlessGL::EndFrame() {
if (!m_usable) return;
eglSwapBuffers(static_cast<EGLDisplay>(m_display), static_cast<EGLSurface>(m_surface));
++m_frameIndex;
}
void HeadlessGL::ShutDown() {
if (!m_usable) return;
EGLDisplay display = static_cast<EGLDisplay>(m_display);
eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
if (m_context != nullptr) eglDestroyContext(display, static_cast<EGLContext>(m_context));
if (m_surface != nullptr) eglDestroySurface(display, static_cast<EGLSurface>(m_surface));
eglTerminate(display);
m_context = nullptr;
m_surface = nullptr;
m_display = nullptr;
m_usable = false;
m_skipReason = "the headless context has already been torn down";
}
// ---- scenario vocabulary ------------------------------------------------
namespace {
unsigned int CompileStage(GLenum stage, const char* source, std::string* outError) {
const GLuint shader = glCreateShader(stage);
glShaderSource(shader, 1, &source, nullptr);
glCompileShader(shader);
GLint compiled = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
if (compiled == GL_FALSE) {
char log[2048] = {};
GLsizei length = 0;
glGetShaderInfoLog(shader, sizeof(log) - 1, &length, log);
if (outError != nullptr) {
*outError = std::string(stage == GL_VERTEX_SHADER ? "vertex" : "fragment") +
" shader failed to compile: " + log;
}
glDeleteShader(shader);
return 0;
}
return shader;
}
} // namespace
unsigned int CompileProgram(const char* vertexSource, const char* fragmentSource, std::string* outError) {
const GLuint vs = CompileStage(GL_VERTEX_SHADER, vertexSource, outError);
if (vs == 0) return 0;
const GLuint fs = CompileStage(GL_FRAGMENT_SHADER, fragmentSource, outError);
if (fs == 0) {
glDeleteShader(vs);
return 0;
}
const GLuint program = glCreateProgram();
glAttachShader(program, vs);
glAttachShader(program, fs);
// Pinned rather than queried so the scenarios can set up a VAO without a
// round trip, and so a driver that reorders attributes cannot change what
// the test means.
glBindAttribLocation(program, 0, "aPos");
glBindAttribLocation(program, 1, "aColor");
glLinkProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
GLint linked = 0;
glGetProgramiv(program, GL_LINK_STATUS, &linked);
if (linked == GL_FALSE) {
char log[2048] = {};
GLsizei length = 0;
glGetProgramInfoLog(program, sizeof(log) - 1, &length, log);
if (outError != nullptr) *outError = std::string("program failed to link: ") + log;
glDeleteProgram(program);
return 0;
}
return program;
}
ColorFbo MakeColorFbo(int width, int height) {
ColorFbo target;
target.width = width;
target.height = height;
glGenTextures(1, &target.texture);
glBindTexture(GL_TEXTURE_2D, target.texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glBindTexture(GL_TEXTURE_2D, 0);
glGenFramebuffers(1, &target.fbo);
glBindFramebuffer(GL_FRAMEBUFFER, target.fbo);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, target.texture, 0);
const GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
if (status != GL_FRAMEBUFFER_COMPLETE) {
DestroyColorFbo(target);
}
return target;
}
void DestroyColorFbo(ColorFbo& target) {
if (target.fbo != 0) glDeleteFramebuffers(1, &target.fbo);
if (target.texture != 0) glDeleteTextures(1, &target.texture);
target.fbo = 0;
target.texture = 0;
}
void BindDefaultFramebuffer() {
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0, 0, HeadlessGL::Get().Width(), HeadlessGL::Get().Height());
}
void BindFbo(const ColorFbo& target) {
glBindFramebuffer(GL_FRAMEBUFFER, target.fbo);
glViewport(0, 0, target.width, target.height);
}
void ClearTo(float r, float g, float b, float a) {
glClearColor(r, g, b, a);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
Image ReadPixels(int width, int height) {
return ReadPixelsRect(0, 0, width, height);
}
Image ReadPixelsRect(int x, int y, int width, int height) {
Image image(width, height);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, image.Data());
return image;
}
unsigned int FirstGLError() {
const GLenum first = glGetError();
if (first == GL_NO_ERROR) return GL_NO_ERROR;
// Drain, bounded: a broken stack must not turn an error check into a hang.
for (int i = 0; i < 64 && glGetError() != GL_NO_ERROR; ++i) {}
return first;
}
const char* GLErrorName(unsigned int error) {
switch (error) {
case GL_NO_ERROR:
return "GL_NO_ERROR";
case GL_INVALID_ENUM:
return "GL_INVALID_ENUM";
case GL_INVALID_VALUE:
return "GL_INVALID_VALUE";
case GL_INVALID_OPERATION:
return "GL_INVALID_OPERATION";
case GL_OUT_OF_MEMORY:
return "GL_OUT_OF_MEMORY";
case GL_INVALID_FRAMEBUFFER_OPERATION:
return "GL_INVALID_FRAMEBUFFER_OPERATION";
default:
return "GL_<unknown>";
}
}
} // namespace MGITest