1 files changed, 148 insertions, 0 deletions
diff --git a/gfx/src/X11Util.h b/gfx/src/X11Util.h
new file mode 100644
index 000000000..e04913342
--- /dev/null
+++ b/gfx/src/X11Util.h
@@ -0,0 +1,148 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* 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 mozilla_X11Util_h
+#define mozilla_X11Util_h
+
+// Utilities common to all X clients, regardless of UI toolkit.
+
+#if defined(MOZ_WIDGET_GTK)
+#  include <gdk/gdk.h>
+#  include <gdk/gdkx.h>
+#  include "X11UndefineNone.h"
+#else
+#  error Unknown toolkit
+#endif
+
+#include <string.h>                     // for memset
+#include "mozilla/Scoped.h"             // for SCOPED_TEMPLATE
+
+namespace mozilla {
+
+/**
+ * Return the default X Display created and used by the UI toolkit.
+ */
+inline Display*
+DefaultXDisplay()
+{
+#if defined(MOZ_WIDGET_GTK)
+  return GDK_DISPLAY_XDISPLAY(gdk_display_get_default());
+#endif
+}
+
+/**
+ * Sets *aVisual to point to aDisplay's Visual struct corresponding to
+ * aVisualID, and *aDepth to its depth.  When aVisualID is None, these are set
+ * to nullptr and 0 respectively.  Both out-parameter pointers are assumed
+ * non-nullptr.
+ */
+void
+FindVisualAndDepth(Display* aDisplay, VisualID aVisualID,
+                   Visual** aVisual, int* aDepth);
+
+
+/**
+ * Ensure that all X requests have been processed.
+ *
+ * This is similar to XSync, but doesn't need a round trip if the previous
+ * request was synchronous or if events have been received since the last
+ * request.  Subsequent FinishX calls will be noops if there have been no
+ * intermediate requests.
+ */
+
+void
+FinishX(Display* aDisplay);
+
+/**
+ * Invoke XFree() on a pointer to memory allocated by Xlib (if the
+ * pointer is nonnull) when this class goes out of scope.
+ */
+template <typename T>
+struct ScopedXFreePtrTraits
+{
+  typedef T *type;
+  static T *empty() { return nullptr; }
+  static void release(T *ptr) { if (ptr != nullptr) XFree(ptr); }
+};
+SCOPED_TEMPLATE(ScopedXFree, ScopedXFreePtrTraits)
+
+/**
+ * On construction, set a graceful X error handler that doesn't crash the application and records X errors.
+ * On destruction, restore the X error handler to what it was before construction.
+ * 
+ * The SyncAndGetError() method allows to know whether a X error occurred, optionally allows to get the full XErrorEvent,
+ * and resets the recorded X error state so that a single X error will be reported only once.
+ *
+ * Nesting is correctly handled: multiple nested ScopedXErrorHandler's don't interfere with each other's state. However,
+ * if SyncAndGetError is not called on the nested ScopedXErrorHandler, then any X errors caused by X calls made while the nested
+ * ScopedXErrorHandler was in place may then be caught by the other ScopedXErrorHandler. This is just a result of X being
+ * asynchronous and us not doing any implicit syncing: the only method in this class what causes syncing is SyncAndGetError().
+ *
+ * This class is not thread-safe at all. It is assumed that only one thread is using any ScopedXErrorHandler's. Given that it's
+ * not used on Mac, it should be easy to make it thread-safe by using thread-local storage with __thread.
+ */
+class ScopedXErrorHandler
+{
+public:
+    // trivial wrapper around XErrorEvent, just adding ctor initializing by zero.
+    struct ErrorEvent
+    {
+        XErrorEvent mError;
+
+        ErrorEvent()
+        {
+            memset(this, 0, sizeof(ErrorEvent));
+        }
+    };
+
+private:
+
+    // this ScopedXErrorHandler's ErrorEvent object
+    ErrorEvent mXError;
+
+    // static pointer for use by the error handler
+    static ErrorEvent* sXErrorPtr;
+
+    // what to restore sXErrorPtr to on destruction
+    ErrorEvent* mOldXErrorPtr;
+
+    // what to restore the error handler to on destruction
+    int (*mOldErrorHandler)(Display *, XErrorEvent *);
+
+public:
+
+    static int
+    ErrorHandler(Display *, XErrorEvent *ev);
+
+    /**
+     * @param aAllowOffMainThread whether to warn if used off main thread
+     */
+    explicit ScopedXErrorHandler(bool aAllowOffMainThread = false);
+
+    ~ScopedXErrorHandler();
+
+    /** \returns true if a X error occurred since the last time this method was called on this ScopedXErrorHandler object,
+     *           or since the creation of this ScopedXErrorHandler object if this method was never called on it.
+     *
+     * \param ev this optional parameter, if set, will be filled with the XErrorEvent object. If multiple errors occurred,
+     *           the first one will be returned.
+     */
+    bool SyncAndGetError(Display *dpy, XErrorEvent *ev = nullptr);
+};
+
+class OffMainThreadScopedXErrorHandler : public ScopedXErrorHandler
+{
+public:
+  OffMainThreadScopedXErrorHandler()
+    : ScopedXErrorHandler(true)
+  {
+  }
+};
+
+} // namespace mozilla
+
+#endif  // mozilla_X11Util_h