1/*
2 * Copyright 2010-2011 PathScale, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice,
8 *    this list of conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 *    this list of conditions and the following disclaimer in the documentation
12 *    and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
15 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
16 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
21 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
23 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
24 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "typeinfo.h"
28#include <stdio.h>
29
30using namespace ABI_NAMESPACE;
31
32/**
33 * Vtable header.
34 */
35struct vtable_header
36{
37	/** Offset of the leaf object. */
38	ptrdiff_t leaf_offset;
39	/** Type of the object. */
40	const __class_type_info *type;
41};
42
43/**
44 * Simple macro that does pointer arithmetic in bytes but returns a value of
45 * the same type as the original.
46 */
47#define ADD_TO_PTR(x, off) (__typeof__(x))(((char*)x) + off)
48
49bool std::type_info::__do_catch(std::type_info const *ex_type,
50                                void **exception_object,
51                                unsigned int outer) const
52{
53	const type_info *type = this;
54
55	if (type == ex_type)
56	{
57		return true;
58	}
59	if (const __class_type_info *cti = dynamic_cast<const __class_type_info *>(type))
60	{
61		return ex_type->__do_upcast(cti, exception_object);
62	}
63	return false;
64}
65
66bool __pbase_type_info::__do_catch(std::type_info const *ex_type,
67                                   void **exception_object,
68                                   unsigned int outer) const
69{
70	if (ex_type == this)
71	{
72		return true;
73	}
74	if (!ex_type->__is_pointer_p())
75	{
76		// Can't catch a non-pointer type in a pointer catch
77		return false;
78	}
79
80	if (!(outer & 1))
81	{
82		// If the low bit is cleared on this means that we've gone
83		// through a pointer that is not const qualified.
84		return false;
85	}
86	// Clear the low bit on outer if we're not const qualified.
87	if (!(__flags & __const_mask))
88	{
89		outer &= ~1;
90	}
91
92	const __pbase_type_info *ptr_type =
93	        static_cast<const __pbase_type_info*>(ex_type);
94
95	if (ptr_type->__flags & ~__flags)
96	{
97		// Handler pointer is less qualified
98		return false;
99	}
100
101	// Special case for void* handler.
102	if(*__pointee == typeid(void))
103	{
104		return true;
105	}
106
107	return __pointee->__do_catch(ptr_type->__pointee, exception_object, outer);
108}
109
110void *__class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
111{
112	if (this == other)
113	{
114		return obj;
115	}
116	return 0;
117}
118
119void *__si_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
120{
121	if (this == other)
122	{
123		return obj;
124	}
125	return __base_type->cast_to(obj, other);
126}
127bool __si_class_type_info::__do_upcast(const __class_type_info *target,
128                                     void **thrown_object) const
129{
130	if (this == target)
131	{
132		return true;
133	}
134	return __base_type->__do_upcast(target, thrown_object);
135}
136
137void *__vmi_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
138{
139	if (__do_upcast(other, &obj))
140	{
141		return obj;
142	}
143	return 0;
144}
145
146bool __vmi_class_type_info::__do_upcast(const __class_type_info *target,
147		                      void **thrown_object) const
148{
149	if (this == target)
150	{
151		return true;
152	}
153	for (unsigned int i=0 ; i<__base_count ; i++)
154	{
155		const __base_class_type_info *info = &__base_info[i];
156		ptrdiff_t offset = info->offset();
157		// If this is a virtual superclass, the offset is stored in the
158		// object's vtable at the offset requested; 2.9.5.6.c:
159		//
160		// 'For a non-virtual base, this is the offset in the object of the
161		// base subobject. For a virtual base, this is the offset in the
162		// virtual table of the virtual base offset for the virtual base
163		// referenced (negative).'
164
165		void *obj = *thrown_object;
166		if (info->isVirtual())
167		{
168			// Object's vtable
169			ptrdiff_t *off = *(ptrdiff_t**)obj;
170			// Offset location in vtable
171			off = ADD_TO_PTR(off, offset);
172			offset = *off;
173		}
174		void *cast = ADD_TO_PTR(obj, offset);
175
176		if (info->__base_type == target ||
177		    (info->__base_type->__do_upcast(target, &cast)))
178		{
179			*thrown_object = cast;
180			return true;
181		}
182	}
183	return 0;
184}
185
186
187/**
188 * ABI function used to implement the dynamic_cast<> operator.  Some cases of
189 * this operator are implemented entirely in the compiler (e.g. to void*).
190 * This function implements the dynamic casts of the form dynamic_cast<T>(v).
191 * This will be translated to a call to this function with the value v as the
192 * first argument.  The type id of the static type of v is the second argument
193 * and the type id of the destination type (T) is the third argument.
194 *
195 * The third argument is a hint about the compiler's guess at the correct
196 * pointer offset.  If this value is negative, then -1 indicates no hint, -2
197 * that src is not a public base of dst, and -3 that src is a multiple public
198 * base type but never a virtual base type
199 */
200extern "C" void* __dynamic_cast(const void *sub,
201                                const __class_type_info *src,
202                                const __class_type_info *dst,
203                                ptrdiff_t src2dst_offset)
204{
205	char *vtable_location = *(char**)sub;
206	const vtable_header *header =
207		(const vtable_header*)(vtable_location - sizeof(vtable_header));
208	void *leaf = ADD_TO_PTR((void*)sub, header->leaf_offset);
209	return header->type->cast_to(leaf, dst);
210}
211