1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
// Copyright (c) 2009, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef GOOGLE_BREAKPAD_COMMON_MEMORY_H_
#define GOOGLE_BREAKPAD_COMMON_MEMORY_H_
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <memory>
#include <vector>
#ifdef __APPLE__
#define sys_mmap mmap
#define sys_mmap2 mmap
#define sys_munmap munmap
#define MAP_ANONYMOUS MAP_ANON
#else
#include "third_party/lss/linux_syscall_support.h"
#endif
namespace google_breakpad {
// This is very simple allocator which fetches pages from the kernel directly.
// Thus, it can be used even when the heap may be corrupted.
//
// There is no free operation. The pages are only freed when the object is
// destroyed.
class PageAllocator {
public:
PageAllocator()
: page_size_(getpagesize()),
last_(NULL),
current_page_(NULL),
page_offset_(0) {
}
~PageAllocator() {
FreeAll();
}
void *Alloc(size_t bytes) {
if (!bytes)
return NULL;
if (current_page_ && page_size_ - page_offset_ >= bytes) {
uint8_t *const ret = current_page_ + page_offset_;
page_offset_ += bytes;
if (page_offset_ == page_size_) {
page_offset_ = 0;
current_page_ = NULL;
}
return ret;
}
const size_t pages =
(bytes + sizeof(PageHeader) + page_size_ - 1) / page_size_;
uint8_t *const ret = GetNPages(pages);
if (!ret)
return NULL;
page_offset_ =
(page_size_ - (page_size_ * pages - (bytes + sizeof(PageHeader)))) %
page_size_;
current_page_ = page_offset_ ? ret + page_size_ * (pages - 1) : NULL;
return ret + sizeof(PageHeader);
}
// Checks whether the page allocator owns the passed-in pointer.
// This method exists for testing pursposes only.
bool OwnsPointer(const void* p) {
for (PageHeader* header = last_; header; header = header->next) {
const char* current = reinterpret_cast<char*>(header);
if ((p >= current) && (p < current + header->num_pages * page_size_))
return true;
}
return false;
}
private:
uint8_t *GetNPages(size_t num_pages) {
#if defined(__x86_64__) || defined(__aarch64__)
void *a = sys_mmap(NULL, page_size_ * num_pages, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
#else
void *a = sys_mmap2(NULL, page_size_ * num_pages, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
#endif
if (a == MAP_FAILED)
return NULL;
struct PageHeader *header = reinterpret_cast<PageHeader*>(a);
header->next = last_;
header->num_pages = num_pages;
last_ = header;
return reinterpret_cast<uint8_t*>(a);
}
void FreeAll() {
PageHeader *next;
for (PageHeader *cur = last_; cur; cur = next) {
next = cur->next;
sys_munmap(cur, cur->num_pages * page_size_);
}
}
struct PageHeader {
PageHeader *next; // pointer to the start of the next set of pages.
size_t num_pages; // the number of pages in this set.
};
const size_t page_size_;
PageHeader *last_;
uint8_t *current_page_;
size_t page_offset_;
};
// Wrapper to use with STL containers
template <typename T>
struct PageStdAllocator : public std::allocator<T> {
typedef typename std::allocator<T>::pointer pointer;
typedef typename std::allocator<T>::size_type size_type;
explicit PageStdAllocator(PageAllocator& allocator): allocator_(allocator) {}
template <class Other> PageStdAllocator(const PageStdAllocator<Other>& other)
: allocator_(other.allocator_) {}
inline pointer allocate(size_type n, const void* = 0) {
return static_cast<pointer>(allocator_.Alloc(sizeof(T) * n));
}
inline void deallocate(pointer, size_type) {
// The PageAllocator doesn't free.
}
template <typename U> struct rebind {
typedef PageStdAllocator<U> other;
};
private:
// Silly workaround for the gcc from Android's ndk (gcc 4.6), which will
// otherwise complain that `other.allocator_` is private in the constructor
// code.
template<typename Other> friend struct PageStdAllocator;
PageAllocator& allocator_;
};
// A wasteful vector is a std::vector, except that it allocates memory from a
// PageAllocator. It's wasteful because, when resizing, it always allocates a
// whole new array since the PageAllocator doesn't support realloc.
template<class T>
class wasteful_vector : public std::vector<T, PageStdAllocator<T> > {
public:
wasteful_vector(PageAllocator* allocator, unsigned size_hint = 16)
: std::vector<T, PageStdAllocator<T> >(PageStdAllocator<T>(*allocator)) {
std::vector<T, PageStdAllocator<T> >::reserve(size_hint);
}
};
} // namespace google_breakpad
inline void* operator new(size_t nbytes,
google_breakpad::PageAllocator& allocator) {
return allocator.Alloc(nbytes);
}
#endif // GOOGLE_BREAKPAD_COMMON_MEMORY_H_
|
