-
Notifications
You must be signed in to change notification settings - Fork 2k
Expand file tree
/
Copy pathCodeBlockHash.cpp
More file actions
104 lines (88 loc) · 4.1 KB
/
CodeBlockHash.cpp
File metadata and controls
104 lines (88 loc) · 4.1 KB
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
/*
* Copyright (C) 2012-2020 Apple 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:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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.
*/
#include "config.h"
#include "CodeBlockHash.h"
#include "SourceCode.h"
#include <wtf/SHA1.h>
#include <wtf/SixCharacterHash.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
CodeBlockHash::CodeBlockHash(std::span<const char, stringLength> string)
: m_hash(sixCharacterHashStringToInteger(string))
{
}
CodeBlockHash::CodeBlockHash(StringView codeBlockSourceCode, StringView entireSourceCode, CodeSpecializationKind kind)
{
SHA1 sha1;
// The maxSourceCodeLengthToHash is a heuristic to avoid crashing fuzzers
// due to resource exhaustion. This is OK to do because:
// 1. CodeBlockHash is not a critical hash.
// 2. In practice, reasonable source code are not 500 MB or more long.
// 3. And if they are that long, then we are still diversifying the hash on
// their length. But if they do collide, it's OK.
// The only invariant here is that we should always produce the same hash
// for the same source string. The algorithm below achieves that.
constexpr unsigned maxSourceCodeLengthToHash = 500 * MB;
if (static_cast<unsigned>(codeBlockSourceCode.length()) < maxSourceCodeLengthToHash)
sha1.addUTF8Bytes(codeBlockSourceCode);
else {
// Just hash with the length and samples of the source string instead.
unsigned index = 0;
unsigned oldIndex = 0;
unsigned length = entireSourceCode.length();
unsigned step = (length >> 10) + 1;
sha1.addBytes(std::span { std::bit_cast<uint8_t*>(&length), sizeof(length) });
do {
char16_t character = entireSourceCode[index];
sha1.addBytes(std::span { std::bit_cast<uint8_t*>(&character), sizeof(character) });
oldIndex = index;
index += step;
} while (index > oldIndex && index < length);
}
SHA1::Digest digest;
sha1.computeHash(digest);
m_hash = digest[0] | (digest[1] << 8) | (digest[2] << 16) | (digest[3] << 24);
if (m_hash == 0 || m_hash == 1)
m_hash += 0x2d5a93d0; // Ensures a non-zero hash, and gets us #Azero0 for CodeForCall and #Azero1 for CodeForConstruct.
static_assert(!static_cast<unsigned>(CodeSpecializationKind::CodeForCall));
static_assert(static_cast<unsigned>(CodeSpecializationKind::CodeForConstruct));
m_hash ^= static_cast<unsigned>(kind);
ASSERT(m_hash);
}
CodeBlockHash::CodeBlockHash(const SourceCode& sourceCode, CodeSpecializationKind kind)
: CodeBlockHash(sourceCode.view(), sourceCode.provider()->source(), kind)
{
}
void CodeBlockHash::dump(PrintStream& out) const
{
auto buffer = integerToSixCharacterHashString(m_hash);
#if ASSERT_ENABLED
CodeBlockHash recompute(buffer);
ASSERT(recompute == *this);
#endif // ASSERT_ENABLED
out.print(std::span<const char> { buffer });
}
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END