1#!/usr/bin/env python
2
3# Copyright 2019 the V8 project authors. All rights reserved.
4# Use of this source code is governed by a BSD-style license that can be found
5# in the LICENSE file.
6
7import io
8import math
9import struct
10import sys
11
12CUSTOM_SECTION_ID = 0
13FUNCTION_SECTION_ID = 3
14
15def peek_uint8(fin):
16  bs = fin.peek(1)[:1]
17  if len(bs) != 1:
18    return None, bs
19  return ord(bs[0]), bs
20
21def read_uint8(fin):
22  value, bs = peek_uint8(fin)
23  fin.read(len(bs))
24  return value, bs
25
26def peek_uint32(fin):
27  bs = fin.peek(4)[:4]
28  if len(bs) != 4:
29    return None, bs
30  return ord(bs[0]) | ord(bs[1]) << 8 | ord(bs[2]) << 16 | ord(bs[3]) << 24, bs
31
32def read_uint32(fin):
33  value, bs = peek_uint32(fin)
34  fin.read(len(bs))
35  return value, bs
36
37def peek_varuintN(fin):
38  value = 0
39  shift = 0
40  n = 1
41  while True:
42    bs = fin.peek(n)[:n]
43    if len(bs) < n:
44      return None, bs
45    b = ord(bs[-1])
46    value |= (b & 0x7F) << shift;
47    if (b & 0x80) == 0x00:
48      return value, bs
49    shift += 7;
50    n += 1
51
52def read_varuintN(fin):
53  value, bs = peek_varuintN(fin)
54  fin.read(len(bs))
55  return value, bs
56
57def to_varuintN(value):
58  bs = ""
59  while True:
60    b = value & 0x7F
61    value >>= 7
62    if (value != 0x00):
63      b |= 0x80
64    bs += chr(b)
65    if value == 0x00:
66      return bs
67
68def write_varuintN(value, fout):
69  bs = to_varuintN(value)
70  fout.write(bs)
71  return bs
72
73def peek_magic_number(fin, expected_magic_number=0x6d736100):
74  magic_number, bs = peek_uint32(fin)
75  assert magic_number == expected_magic_number, "unexpected magic number"
76  return magic_number, bs
77
78def read_magic_number(fin, expected_magic_number=0x6d736100):
79  magic_number, bs = peek_magic_number(fin, expected_magic_number)
80  fin.read(len(bs))
81  return magic_number, bs
82
83def peek_version(fin, expected_version=1):
84  version, bs = peek_uint32(fin)
85  assert version == expected_version, "unexpected version"
86  return version, bs
87
88def read_version(fin, expected_version=1):
89  version, bs = peek_version(fin, expected_version)
90  fin.read(len(bs))
91  return version, bs
92
93def write_custom_section(fout, section_name_bs, payload_bs):
94  section_name_length_bs = to_varuintN(len(section_name_bs))
95  payload_length_bs = to_varuintN(len(section_name_bs) \
96      + len(section_name_length_bs) + len(payload_bs))
97  section_id_bs = to_varuintN(CUSTOM_SECTION_ID)
98  fout.write(section_id_bs)
99  fout.write(payload_length_bs)
100  fout.write(section_name_length_bs)
101  fout.write(section_name_bs)
102  fout.write(payload_bs)
103
104def write_compilation_hints_section(fout, hints_bs):
105  num_compilation_hints_bs = to_varuintN(len(hints_bs))
106  section_name_bs = b"compilationHints"
107  payload_bs = num_compilation_hints_bs + hints_bs
108  write_custom_section(fout, section_name_bs, payload_bs)
109