1 // as_function.cpp: ActionScript Functions, for Gnash.
2 //
3 // Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
4 // Free Software Foundation, Inc
5 //
6 // This program is free software; you can redistribute it and/or modify
7 // it under the terms of the GNU General Public License as published by
8 // the Free Software Foundation; either version 3 of the License, or
9 // (at your option) any later version.
10 //
11 // This program is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 //
16 // You should have received a copy of the GNU General Public License
17 // along with this program; if not, write to the Free Software
18 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 //
20
21 #include "as_function.h"
22
23 #include <string>
24
25 #include "log.h"
26 #include "as_value.h"
27 #include "fn_call.h"
28 #include "GnashException.h"
29 #include "Global_as.h"
30 #include "namedStrings.h"
31
32 namespace gnash {
33
as_function(Global_as & gl)34 as_function::as_function(Global_as& gl)
35 :
36 as_object(gl)
37 {
38 }
39
40 std::string
stringValue() const41 as_function::stringValue() const
42 {
43 return "[type Function]";
44 }
45
46 as_object*
constructInstance(as_function & ctor,const as_environment & env,fn_call::Args & args)47 constructInstance(as_function& ctor, const as_environment& env,
48 fn_call::Args& args)
49 {
50 Global_as& gl = getGlobal(ctor);
51
52 // Create an empty object, with a ref to the constructor's prototype.
53 // The function's prototype property always becomes the new object's
54 // __proto__ member, regardless of whether it is an object and regardless
55 // of its visibility.
56 as_object* newobj = new as_object(gl);
57 Property* proto = ctor.getOwnProperty(NSV::PROP_PROTOTYPE);
58 if (proto) newobj->set_prototype(proto->getValue(ctor));
59
60 return ctor.construct(*newobj, env, args);
61 }
62
63 as_object*
construct(as_object & newobj,const as_environment & env,fn_call::Args & args)64 as_function::construct(as_object& newobj, const as_environment& env,
65 fn_call::Args& args)
66 {
67 const int swfversion = getSWFVersion(env);
68
69 // Add a __constructor__ member to the new object visible from version 6.
70 const int flags = PropFlags::dontEnum |
71 PropFlags::onlySWF6Up;
72
73 newobj.init_member(NSV::PROP_uuCONSTRUCTORuu, this, flags);
74
75 if (swfversion < 7) {
76 newobj.init_member(NSV::PROP_CONSTRUCTOR, this, PropFlags::dontEnum);
77 }
78
79 // Don't set a super so that it will be constructed only if required
80 // by the function.
81 fn_call fn(&newobj, env, args, nullptr, true);
82 as_value ret;
83
84 try {
85 ret = call(fn);
86 }
87 catch (const GnashException& ex) {
88 // Catching a std::exception here can mask all sorts of bad
89 // behaviour, as (for instance) a poorly constructed string may
90 // smash the stack, throw an exception, but not abort.
91 // This is very effective at confusing debugging tools.
92 // We only throw GnashExceptions. A std::bad_alloc may also be
93 // reasonable, but anything else shouldn't be caught here.
94 log_error(_("Native function called as constructor threw exception: %s")
95 , ex.what());
96
97 // If a constructor throws an exception, throw it back to the
98 // caller. This is the only way to signal that a constructor
99 // did not return anything.
100 throw;
101 }
102
103 // Some built-in constructors do things properly and operate on the
104 // 'this' pointer. Others return a new object. This is to handle those
105 // cases.
106 if (isBuiltin() && ret.is_object()) {
107 as_object* fakeobj = toObject(ret, getVM(env));
108
109 fakeobj->init_member(NSV::PROP_uuCONSTRUCTORuu, as_value(this),
110 flags);
111
112 // Also for SWF5+ only?
113 if (swfversion < 7) {
114 fakeobj->init_member(NSV::PROP_CONSTRUCTOR, as_value(this),
115 PropFlags::dontEnum);
116 }
117 return fakeobj;
118 }
119
120 return &newobj;
121 }
122
123 } // namespace gnash
124