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comparison: dom/plugins/ipc/interpose/plugin_child_interpose.mm

dom/plugins/ipc/interpose/plugin_child_interpose.mm

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TOR_BUG_3246
changeset 7
129ffea94266
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-1:000000000000 0:ad59148c1032
1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5
6 // Use "dyld interposing" to hook methods imported from other libraries in the
7 // plugin child process. The basic technique is described at
8 // http://books.google.com/books?id=K8vUkpOXhN4C&pg=PA73&lpg=PA73&dq=__interpose&source=bl&ots=OJnnXZYpZC&sig=o7I3lXvoduUi13SrPfOON7o3do4&hl=en&ei=AoehS9brCYGQNrvsmeUM&sa=X&oi=book_result&ct=result&resnum=6&ved=0CBsQ6AEwBQ#v=onepage&q=__interpose&f=false.
9 // The idea of doing it for the plugin child process comes from Chromium code,
10 // particularly from plugin_carbon_interpose_mac.cc
11 // (http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/chrome/browser/plugin_carbon_interpose_mac.cc&q=nscursor&exact_package=chromium&d=1&l=168)
12 // and from PluginProcessHost::Init() in plugin_process_host.cc
13 // (http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/content/browser/plugin_process_host.cc&q=nscursor&exact_package=chromium&d=1&l=222).
14
15 // These hooks are needed to make certain OS calls work from the child process
16 // (a background process) that would normally only work when called in the
17 // parent process (the foreground process). They allow us to serialize
18 // information from the child process to the parent process, so that the same
19 // (or equivalent) calls can be made from the parent process.
20
21 // This file lives in a seperate module (libplugin_child_interpose.dylib),
22 // which will get loaded by the OS before any other modules when the plugin
23 // child process is launched (from GeckoChildProcessHost::
24 // PerformAsyncLaunchInternal()). For this reason it shouldn't link in other
25 // browser modules when loaded. Instead it should use dlsym() to load
26 // pointers to the methods it wants to call in other modules.
27
28 #if !defined(__LP64__)
29
30 #include <dlfcn.h>
31 #import <Carbon/Carbon.h>
32
33 // The header file QuickdrawAPI.h is missing on OS X 10.7 and up (though the
34 // QuickDraw APIs defined in it are still present) -- so we need to supply the
35 // relevant parts of its contents here. It's likely that Apple will eventually
36 // remove the APIs themselves (probably in OS X 10.8), so we need to make them
37 // weak imports, and test for their presence before using them.
38 #if !defined(__QUICKDRAWAPI__)
39
40 struct Cursor;
41 extern "C" void SetCursor(const Cursor * crsr) __attribute__((weak_import));
42
43 #endif /* __QUICKDRAWAPI__ */
44
45 BOOL (*OnSetThemeCursorPtr) (ThemeCursor) = NULL;
46 BOOL (*OnSetCursorPtr) (const Cursor*) = NULL;
47 BOOL (*OnHideCursorPtr) () = NULL;
48 BOOL (*OnShowCursorPtr) () = NULL;
49
50 static BOOL loadXULPtrs()
51 {
52 if (!OnSetThemeCursorPtr) {
53 // mac_plugin_interposing_child_OnSetThemeCursor(ThemeCursor cursor) is in
54 // PluginInterposeOSX.mm
55 OnSetThemeCursorPtr = (BOOL(*)(ThemeCursor))
56 dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnSetThemeCursor");
57 }
58 if (!OnSetCursorPtr) {
59 // mac_plugin_interposing_child_OnSetCursor(const Cursor* cursor) is in
60 // PluginInterposeOSX.mm
61 OnSetCursorPtr = (BOOL(*)(const Cursor*))
62 dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnSetCursor");
63 }
64 if (!OnHideCursorPtr) {
65 // mac_plugin_interposing_child_OnHideCursor() is in PluginInterposeOSX.mm
66 OnHideCursorPtr = (BOOL(*)())
67 dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnHideCursor");
68 }
69 if (!OnShowCursorPtr) {
70 // mac_plugin_interposing_child_OnShowCursor() is in PluginInterposeOSX.mm
71 OnShowCursorPtr = (BOOL(*)())
72 dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnShowCursor");
73 }
74 return (OnSetCursorPtr && OnSetThemeCursorPtr && OnHideCursorPtr && OnShowCursorPtr);
75 }
76
77 static OSStatus MacPluginChildSetThemeCursor(ThemeCursor cursor)
78 {
79 if (loadXULPtrs()) {
80 OnSetThemeCursorPtr(cursor);
81 }
82 return ::SetThemeCursor(cursor);
83 }
84
85 static void MacPluginChildSetCursor(const Cursor* cursor)
86 {
87 if (::SetCursor) {
88 if (loadXULPtrs()) {
89 OnSetCursorPtr(cursor);
90 }
91 ::SetCursor(cursor);
92 }
93 }
94
95 static CGError MacPluginChildCGDisplayHideCursor(CGDirectDisplayID display)
96 {
97 if (loadXULPtrs()) {
98 OnHideCursorPtr();
99 }
100 return ::CGDisplayHideCursor(display);
101 }
102
103 static CGError MacPluginChildCGDisplayShowCursor(CGDirectDisplayID display)
104 {
105 if (loadXULPtrs()) {
106 OnShowCursorPtr();
107 }
108 return ::CGDisplayShowCursor(display);
109 }
110
111 #pragma mark -
112
113 struct interpose_substitution {
114 const void* replacement;
115 const void* original;
116 };
117
118 #define INTERPOSE_FUNCTION(function) \
119 { reinterpret_cast<const void*>(MacPluginChild##function), \
120 reinterpret_cast<const void*>(function) }
121
122 __attribute__((used)) static const interpose_substitution substitutions[]
123 __attribute__((section("__DATA, __interpose"))) = {
124 INTERPOSE_FUNCTION(SetThemeCursor),
125 INTERPOSE_FUNCTION(CGDisplayHideCursor),
126 INTERPOSE_FUNCTION(CGDisplayShowCursor),
127 // SetCursor() and other QuickDraw APIs will probably be removed in OS X
128 // 10.8. But this will make 'SetCursor' NULL, which will just stop the OS
129 // from interposing it (tested using an INTERPOSE_FUNCTION_BROKEN macro
130 // that just sets the second address of each tuple to NULL).
131 INTERPOSE_FUNCTION(SetCursor),
132 };
133
134 #endif // !__LP64__

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