michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: // Use "dyld interposing" to hook methods imported from other libraries in the
michael@0: // plugin child process.  The basic technique is described at
michael@0: // 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.
michael@0: // The idea of doing it for the plugin child process comes from Chromium code,
michael@0: // particularly from plugin_carbon_interpose_mac.cc
michael@0: // (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)
michael@0: // and from PluginProcessHost::Init() in plugin_process_host.cc
michael@0: // (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).
michael@0: 
michael@0: // These hooks are needed to make certain OS calls work from the child process
michael@0: // (a background process) that would normally only work when called in the
michael@0: // parent process (the foreground process).  They allow us to serialize
michael@0: // information from the child process to the parent process, so that the same
michael@0: // (or equivalent) calls can be made from the parent process.
michael@0: 
michael@0: // This file lives in a seperate module (libplugin_child_interpose.dylib),
michael@0: // which will get loaded by the OS before any other modules when the plugin
michael@0: // child process is launched (from GeckoChildProcessHost::
michael@0: // PerformAsyncLaunchInternal()).  For this reason it shouldn't link in other
michael@0: // browser modules when loaded.  Instead it should use dlsym() to load
michael@0: // pointers to the methods it wants to call in other modules.
michael@0: 
michael@0: #if !defined(__LP64__)
michael@0: 
michael@0: #include <dlfcn.h>
michael@0: #import <Carbon/Carbon.h>
michael@0: 
michael@0: // The header file QuickdrawAPI.h is missing on OS X 10.7 and up (though the
michael@0: // QuickDraw APIs defined in it are still present) -- so we need to supply the
michael@0: // relevant parts of its contents here.  It's likely that Apple will eventually
michael@0: // remove the APIs themselves (probably in OS X 10.8), so we need to make them
michael@0: // weak imports, and test for their presence before using them.
michael@0: #if !defined(__QUICKDRAWAPI__)
michael@0: 
michael@0: struct Cursor;
michael@0: extern "C" void SetCursor(const Cursor * crsr) __attribute__((weak_import));
michael@0: 
michael@0: #endif /* __QUICKDRAWAPI__ */
michael@0: 
michael@0: BOOL (*OnSetThemeCursorPtr) (ThemeCursor) = NULL;
michael@0: BOOL (*OnSetCursorPtr) (const Cursor*) = NULL;
michael@0: BOOL (*OnHideCursorPtr) () = NULL;
michael@0: BOOL (*OnShowCursorPtr) () = NULL;
michael@0: 
michael@0: static BOOL loadXULPtrs()
michael@0: {
michael@0:   if (!OnSetThemeCursorPtr) {
michael@0:     // mac_plugin_interposing_child_OnSetThemeCursor(ThemeCursor cursor) is in
michael@0:     // PluginInterposeOSX.mm
michael@0:     OnSetThemeCursorPtr = (BOOL(*)(ThemeCursor))
michael@0:       dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnSetThemeCursor");
michael@0:   }
michael@0:   if (!OnSetCursorPtr) {
michael@0:     // mac_plugin_interposing_child_OnSetCursor(const Cursor* cursor) is in
michael@0:     // PluginInterposeOSX.mm
michael@0:     OnSetCursorPtr = (BOOL(*)(const Cursor*))
michael@0:       dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnSetCursor");
michael@0:   }
michael@0:   if (!OnHideCursorPtr) {
michael@0:     // mac_plugin_interposing_child_OnHideCursor() is in PluginInterposeOSX.mm
michael@0:     OnHideCursorPtr = (BOOL(*)())
michael@0:       dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnHideCursor");
michael@0:   }
michael@0:   if (!OnShowCursorPtr) {
michael@0:     // mac_plugin_interposing_child_OnShowCursor() is in PluginInterposeOSX.mm
michael@0:     OnShowCursorPtr = (BOOL(*)())
michael@0:       dlsym(RTLD_DEFAULT, "mac_plugin_interposing_child_OnShowCursor");
michael@0:   }
michael@0:   return (OnSetCursorPtr && OnSetThemeCursorPtr && OnHideCursorPtr && OnShowCursorPtr);
michael@0: }
michael@0: 
michael@0: static OSStatus MacPluginChildSetThemeCursor(ThemeCursor cursor)
michael@0: {
michael@0:   if (loadXULPtrs()) {
michael@0:     OnSetThemeCursorPtr(cursor);
michael@0:   }
michael@0:   return ::SetThemeCursor(cursor);
michael@0: }
michael@0: 
michael@0: static void MacPluginChildSetCursor(const Cursor* cursor)
michael@0: {
michael@0:   if (::SetCursor) {
michael@0:     if (loadXULPtrs()) {
michael@0:       OnSetCursorPtr(cursor);
michael@0:     }
michael@0:     ::SetCursor(cursor);
michael@0:   }
michael@0: }
michael@0: 
michael@0: static CGError MacPluginChildCGDisplayHideCursor(CGDirectDisplayID display)
michael@0: {
michael@0:   if (loadXULPtrs()) {
michael@0:     OnHideCursorPtr();
michael@0:   }
michael@0:   return ::CGDisplayHideCursor(display);
michael@0: }
michael@0: 
michael@0: static CGError MacPluginChildCGDisplayShowCursor(CGDirectDisplayID display)
michael@0: {
michael@0:   if (loadXULPtrs()) {
michael@0:     OnShowCursorPtr();
michael@0:   }
michael@0:   return ::CGDisplayShowCursor(display);
michael@0: }
michael@0: 
michael@0: #pragma mark -
michael@0: 
michael@0: struct interpose_substitution {
michael@0:   const void* replacement;
michael@0:   const void* original;
michael@0: };
michael@0: 
michael@0: #define INTERPOSE_FUNCTION(function) \
michael@0:     { reinterpret_cast<const void*>(MacPluginChild##function), \
michael@0:       reinterpret_cast<const void*>(function) }
michael@0: 
michael@0: __attribute__((used)) static const interpose_substitution substitutions[]
michael@0:     __attribute__((section("__DATA, __interpose"))) = {
michael@0:   INTERPOSE_FUNCTION(SetThemeCursor),
michael@0:   INTERPOSE_FUNCTION(CGDisplayHideCursor),
michael@0:   INTERPOSE_FUNCTION(CGDisplayShowCursor),
michael@0:   // SetCursor() and other QuickDraw APIs will probably be removed in OS X
michael@0:   // 10.8.  But this will make 'SetCursor' NULL, which will just stop the OS
michael@0:   // from interposing it (tested using an INTERPOSE_FUNCTION_BROKEN macro
michael@0:   // that just sets the second address of each tuple to NULL).
michael@0:   INTERPOSE_FUNCTION(SetCursor),
michael@0: };
michael@0: 
michael@0: #endif  // !__LP64__