Bug 1828192 [Linux] Implement common glx/vaapi test routines in GfxInfoUtils.h r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D175805

widget/gtk/GfxInfoUtils.h

@@ -0,0 +1,85 @@
+/* vim: se cin sw=2 ts=2 et : */
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WIDGET_GTK_GFXINFO_UTILS_h__
+#define WIDGET_GTK_GFXINFO_UTILS_h__
+
+// An alternative to mozilla::Unused for use in (a) C code and (b) code where
+// linking with unused.o is difficult.
+#define MOZ_UNUSED(expr) \
+  do {                   \
+    if (expr) {          \
+      (void)0;           \
+    }                    \
+  } while (0)
+
+#define LOG_PIPE 2
+
+static bool enable_logging = false;
+static void log(const char* format, ...) {
+  if (!enable_logging) {
+    return;
+  }
+  va_list args;
+  va_start(args, format);
+  vfprintf(stderr, format, args);
+  va_end(args);
+}
+
+// C++ standard collides with C standard in that it doesn't allow casting void*
+// to function pointer types. So the work-around is to convert first to size_t.
+// http://www.trilithium.com/johan/2004/12/problem-with-dlsym/
+template <typename func_ptr_type>
+static func_ptr_type cast(void* ptr) {
+  return reinterpret_cast<func_ptr_type>(reinterpret_cast<size_t>(ptr));
+}
+
+#define BUFFER_SIZE_STEP 4000
+
+static char* test_buf = nullptr;
+static int test_bufsize = 0;
+static int test_length = 0;
+
+static void record_value(const char* format, ...) {
+  if (!test_buf || test_length + BUFFER_SIZE_STEP / 2 > test_bufsize) {
+    test_bufsize += BUFFER_SIZE_STEP;
+    test_buf = (char*)realloc(test_buf, test_bufsize);
+  }
+  int remaining = test_bufsize - test_length;
+
+  // Append the new values to the buffer, not to exceed the remaining space.
+  va_list args;
+  va_start(args, format);
+  int max_added = vsnprintf(test_buf + test_length, remaining, format, args);
+  va_end(args);
+
+  if (max_added >= remaining) {
+    test_length += remaining;
+  } else {
+    test_length += max_added;
+  }
+}
+
+static void record_error(const char* str) { record_value("ERROR\n%s\n", str); }
+
+static void record_warning(const char* str) {
+  record_value("WARNING\n%s\n", str);
+}
+
+static void record_flush(int out_pipe) {
+  if (!test_buf) {
+    return;
+  }
+  MOZ_UNUSED(write(out_pipe, test_buf, test_length));
+  if (enable_logging) {
+    MOZ_UNUSED(write(LOG_PIPE, test_buf, test_length));
+  }
+  free(test_buf);
+  test_buf = nullptr;
+}
+
+#endif /* WIDGET_GTK_GFXINFO_h__ */

widget/gtk/moz.build

@@ -33,6 +33,7 @@ EXPORTS += [
 ]
 
 EXPORTS.mozilla += [
+    "GfxInfoUtils.h",
     "GRefPtr.h",
     "GUniquePtr.h",
     "WidgetUtilsGtk.h",