1 // Copyright 2017 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "components/zucchini/rel32_utils.h"
6
7 #include <algorithm>
8
9 #include "base/check_op.h"
10 #include "components/zucchini/io_utils.h"
11
12 namespace zucchini {
13
14 /******** Rel32ReaderX86 ********/
15
Rel32ReaderX86(ConstBufferView image,offset_t lo,offset_t hi,const std::deque<offset_t> * locations,const AddressTranslator & translator)16 Rel32ReaderX86::Rel32ReaderX86(ConstBufferView image,
17 offset_t lo,
18 offset_t hi,
19 const std::deque<offset_t>* locations,
20 const AddressTranslator& translator)
21 : image_(image),
22 target_rva_to_offset_(translator),
23 location_offset_to_rva_(translator),
24 hi_(hi),
25 last_(locations->end()) {
26 DCHECK_LE(lo, image.size());
27 DCHECK_LE(hi, image.size());
28 current_ = std::lower_bound(locations->begin(), locations->end(), lo);
29 }
30
31 Rel32ReaderX86::~Rel32ReaderX86() = default;
32
GetNext()33 std::optional<Reference> Rel32ReaderX86::GetNext() {
34 while (current_ < last_ && *current_ < hi_) {
35 offset_t loc_offset = *(current_++);
36 DCHECK_LE(loc_offset + 4, image_.size()); // Sanity check.
37 rva_t loc_rva = location_offset_to_rva_.Convert(loc_offset);
38 rva_t target_rva = loc_rva + 4 + image_.read<int32_t>(loc_offset);
39 offset_t target_offset = target_rva_to_offset_.Convert(target_rva);
40 // |locations| is valid by assumption (see class description).
41 DCHECK_NE(kInvalidOffset, target_offset);
42 return Reference{loc_offset, target_offset};
43 }
44 return std::nullopt;
45 }
46
47 /******** Rel32ReceptorX86 ********/
48
Rel32WriterX86(MutableBufferView image,const AddressTranslator & translator)49 Rel32WriterX86::Rel32WriterX86(MutableBufferView image,
50 const AddressTranslator& translator)
51 : image_(image),
52 target_offset_to_rva_(translator),
53 location_offset_to_rva_(translator) {}
54
55 Rel32WriterX86::~Rel32WriterX86() = default;
56
PutNext(Reference ref)57 void Rel32WriterX86::PutNext(Reference ref) {
58 rva_t target_rva = target_offset_to_rva_.Convert(ref.target);
59 rva_t loc_rva = location_offset_to_rva_.Convert(ref.location);
60
61 // Subtraction underflow is okay
62 uint32_t code =
63 static_cast<uint32_t>(target_rva) - (static_cast<uint32_t>(loc_rva) + 4);
64 image_.write<uint32_t>(ref.location, code);
65 }
66
67 } // namespace zucchini
68