blob: 5f5f746fbe071ada5fb85da27012550f4dcd9f0f (
plain)
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
|
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_
#define MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_
#include <stddef.h>
#include "mojo/public/cpp/bindings/lib/buffer.h"
#include "mojo/public/cpp/system/macros.h"
namespace mojo {
namespace internal {
// FixedBuffer provides a simple way to allocate objects within a fixed chunk
// of memory. Objects are allocated by calling the |Allocate| method, which
// extends the buffer accordingly. Objects allocated in this way are not freed
// explicitly. Instead, they remain valid so long as the FixedBuffer remains
// valid. The Leak method may be used to steal the underlying memory from the
// FixedBuffer.
//
// Typical usage:
//
// {
// FixedBuffer buf(8 + 8);
//
// int* a = static_cast<int*>(buf->Allocate(sizeof(int)));
// *a = 2;
//
// double* b = static_cast<double*>(buf->Allocate(sizeof(double)));
// *b = 3.14f;
//
// void* data = buf.Leak();
// Process(data);
//
// free(data);
// }
class FixedBuffer : public Buffer {
public:
FixedBuffer();
// |size| should be aligned using internal::Align.
void Initialize(void* memory, size_t size);
size_t size() const { return size_; }
// Grows the buffer by |num_bytes| and returns a pointer to the start of the
// addition. The resulting address is 8-byte aligned, and the content of the
// memory is zero-filled.
void* Allocate(size_t num_bytes) override;
PickleBuffer* AsPickleBuffer() override;
protected:
char* ptr_;
size_t cursor_;
size_t size_;
MOJO_DISALLOW_COPY_AND_ASSIGN(FixedBuffer);
};
class FixedBufferForTesting : public FixedBuffer {
public:
explicit FixedBufferForTesting(size_t size);
~FixedBufferForTesting() override;
// Returns the internal memory owned by the Buffer to the caller. The Buffer
// relinquishes its pointer, effectively resetting the state of the Buffer
// and leaving the caller responsible for freeing the returned memory address
// when no longer needed.
void* Leak();
private:
MOJO_DISALLOW_COPY_AND_ASSIGN(FixedBufferForTesting);
};
} // namespace internal
} // namespace mojo
#endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_
|
