1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 * vim: sw=2 ts=8 et :
3 */
4 /* This Source Code Form is subject to the terms of the Mozilla Public
5 * License, v. 2.0. If a copy of the MPL was not distributed with this
6 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7
8 #ifndef mozilla_X11Util_h
9 #define mozilla_X11Util_h
10
11 // Utilities common to all X clients, regardless of UI toolkit.
12
13 #if defined(MOZ_WIDGET_GTK)
14 # include <gdk/gdk.h>
15 # include <gdk/gdkx.h>
16 # include "X11UndefineNone.h"
17 #else
18 # error Unknown toolkit
19 #endif
20
21 #include <string.h> // for memset
22 #include "mozilla/Scoped.h" // for SCOPED_TEMPLATE
23
24 namespace mozilla {
25
26 /**
27 * Return the default X Display created and used by the UI toolkit.
28 */
29 inline Display*
DefaultXDisplay()30 DefaultXDisplay()
31 {
32 #if defined(MOZ_WIDGET_GTK)
33 return GDK_DISPLAY_XDISPLAY(gdk_display_get_default());
34 #endif
35 }
36
37 /**
38 * Sets *aVisual to point to aDisplay's Visual struct corresponding to
39 * aVisualID, and *aDepth to its depth. When aVisualID is None, these are set
40 * to nullptr and 0 respectively. Both out-parameter pointers are assumed
41 * non-nullptr.
42 */
43 void
44 FindVisualAndDepth(Display* aDisplay, VisualID aVisualID,
45 Visual** aVisual, int* aDepth);
46
47
48 /**
49 * Ensure that all X requests have been processed.
50 *
51 * This is similar to XSync, but doesn't need a round trip if the previous
52 * request was synchronous or if events have been received since the last
53 * request. Subsequent FinishX calls will be noops if there have been no
54 * intermediate requests.
55 */
56
57 void
58 FinishX(Display* aDisplay);
59
60 /**
61 * Invoke XFree() on a pointer to memory allocated by Xlib (if the
62 * pointer is nonnull) when this class goes out of scope.
63 */
64 template <typename T>
65 struct ScopedXFreePtrTraits
66 {
67 typedef T *type;
emptyScopedXFreePtrTraits68 static T *empty() { return nullptr; }
releaseScopedXFreePtrTraits69 static void release(T *ptr) { if (ptr != nullptr) XFree(ptr); }
70 };
SCOPED_TEMPLATE(ScopedXFree,ScopedXFreePtrTraits)71 SCOPED_TEMPLATE(ScopedXFree, ScopedXFreePtrTraits)
72
73 /**
74 * On construction, set a graceful X error handler that doesn't crash the application and records X errors.
75 * On destruction, restore the X error handler to what it was before construction.
76 *
77 * The SyncAndGetError() method allows to know whether a X error occurred, optionally allows to get the full XErrorEvent,
78 * and resets the recorded X error state so that a single X error will be reported only once.
79 *
80 * Nesting is correctly handled: multiple nested ScopedXErrorHandler's don't interfere with each other's state. However,
81 * if SyncAndGetError is not called on the nested ScopedXErrorHandler, then any X errors caused by X calls made while the nested
82 * ScopedXErrorHandler was in place may then be caught by the other ScopedXErrorHandler. This is just a result of X being
83 * asynchronous and us not doing any implicit syncing: the only method in this class what causes syncing is SyncAndGetError().
84 *
85 * This class is not thread-safe at all. It is assumed that only one thread is using any ScopedXErrorHandler's. Given that it's
86 * not used on Mac, it should be easy to make it thread-safe by using thread-local storage with __thread.
87 */
88 class ScopedXErrorHandler
89 {
90 public:
91 // trivial wrapper around XErrorEvent, just adding ctor initializing by zero.
92 struct ErrorEvent
93 {
94 XErrorEvent mError;
95
96 ErrorEvent()
97 {
98 memset(this, 0, sizeof(ErrorEvent));
99 }
100 };
101
102 private:
103
104 // this ScopedXErrorHandler's ErrorEvent object
105 ErrorEvent mXError;
106
107 // static pointer for use by the error handler
108 static ErrorEvent* sXErrorPtr;
109
110 // what to restore sXErrorPtr to on destruction
111 ErrorEvent* mOldXErrorPtr;
112
113 // what to restore the error handler to on destruction
114 int (*mOldErrorHandler)(Display *, XErrorEvent *);
115
116 public:
117
118 static int
119 ErrorHandler(Display *, XErrorEvent *ev);
120
121 /**
122 * @param aAllowOffMainThread whether to warn if used off main thread
123 */
124 explicit ScopedXErrorHandler(bool aAllowOffMainThread = false);
125
126 ~ScopedXErrorHandler();
127
128 /** \returns true if a X error occurred since the last time this method was called on this ScopedXErrorHandler object,
129 * or since the creation of this ScopedXErrorHandler object if this method was never called on it.
130 *
131 * \param ev this optional parameter, if set, will be filled with the XErrorEvent object. If multiple errors occurred,
132 * the first one will be returned.
133 */
134 bool SyncAndGetError(Display *dpy, XErrorEvent *ev = nullptr);
135 };
136
137 class OffMainThreadScopedXErrorHandler : public ScopedXErrorHandler
138 {
139 public:
OffMainThreadScopedXErrorHandler()140 OffMainThreadScopedXErrorHandler()
141 : ScopedXErrorHandler(true)
142 {
143 }
144 };
145
146 } // namespace mozilla
147
148 #endif // mozilla_X11Util_h
149