1 //===- BinaryStreamRef.cpp - ----------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/Support/BinaryStreamRef.h"
10 #include "llvm/Support/BinaryByteStream.h"
11 
12 using namespace llvm;
13 using namespace llvm::support;
14 
15 namespace {
16 
17 class ArrayRefImpl : public BinaryStream {
18 public:
19   ArrayRefImpl(ArrayRef<uint8_t> Data, endianness Endian) : BBS(Data, Endian) {}
20 
21   llvm::support::endianness getEndian() const override {
22     return BBS.getEndian();
23   }
24   Error readBytes(uint64_t Offset, uint64_t Size,
25                   ArrayRef<uint8_t> &Buffer) override {
26     return BBS.readBytes(Offset, Size, Buffer);
27   }
28   Error readLongestContiguousChunk(uint64_t Offset,
29                                    ArrayRef<uint8_t> &Buffer) override {
30     return BBS.readLongestContiguousChunk(Offset, Buffer);
31   }
32   uint64_t getLength() override { return BBS.getLength(); }
33 
34 private:
35   BinaryByteStream BBS;
36 };
37 
38 class MutableArrayRefImpl : public WritableBinaryStream {
39 public:
40   MutableArrayRefImpl(MutableArrayRef<uint8_t> Data, endianness Endian)
41       : BBS(Data, Endian) {}
42 
43   // Inherited via WritableBinaryStream
44   llvm::support::endianness getEndian() const override {
45     return BBS.getEndian();
46   }
47   Error readBytes(uint64_t Offset, uint64_t Size,
48                   ArrayRef<uint8_t> &Buffer) override {
49     return BBS.readBytes(Offset, Size, Buffer);
50   }
51   Error readLongestContiguousChunk(uint64_t Offset,
52                                    ArrayRef<uint8_t> &Buffer) override {
53     return BBS.readLongestContiguousChunk(Offset, Buffer);
54   }
55   uint64_t getLength() override { return BBS.getLength(); }
56 
57   Error writeBytes(uint64_t Offset, ArrayRef<uint8_t> Data) override {
58     return BBS.writeBytes(Offset, Data);
59   }
60   Error commit() override { return BBS.commit(); }
61 
62 private:
63   MutableBinaryByteStream BBS;
64 };
65 } // namespace
66 
67 BinaryStreamRef::BinaryStreamRef(BinaryStream &Stream)
68     : BinaryStreamRefBase(Stream) {}
69 BinaryStreamRef::BinaryStreamRef(BinaryStream &Stream, uint64_t Offset,
70                                  std::optional<uint64_t> Length)
71     : BinaryStreamRefBase(Stream, Offset, Length) {}
72 BinaryStreamRef::BinaryStreamRef(ArrayRef<uint8_t> Data, endianness Endian)
73     : BinaryStreamRefBase(std::make_shared<ArrayRefImpl>(Data, Endian), 0,
74                           Data.size()) {}
75 BinaryStreamRef::BinaryStreamRef(StringRef Data, endianness Endian)
76     : BinaryStreamRef(ArrayRef(Data.bytes_begin(), Data.bytes_end()), Endian) {}
77 
78 Error BinaryStreamRef::readBytes(uint64_t Offset, uint64_t Size,
79                                  ArrayRef<uint8_t> &Buffer) const {
80   if (auto EC = checkOffsetForRead(Offset, Size))
81     return EC;
82   return BorrowedImpl->readBytes(ViewOffset + Offset, Size, Buffer);
83 }
84 
85 Error BinaryStreamRef::readLongestContiguousChunk(
86     uint64_t Offset, ArrayRef<uint8_t> &Buffer) const {
87   if (auto EC = checkOffsetForRead(Offset, 1))
88     return EC;
89 
90   if (auto EC =
91           BorrowedImpl->readLongestContiguousChunk(ViewOffset + Offset, Buffer))
92     return EC;
93   // This StreamRef might refer to a smaller window over a larger stream.  In
94   // that case we will have read out more bytes than we should return, because
95   // we should not read past the end of the current view.
96   uint64_t MaxLength = getLength() - Offset;
97   if (Buffer.size() > MaxLength)
98     Buffer = Buffer.slice(0, MaxLength);
99   return Error::success();
100 }
101 
102 WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream)
103     : BinaryStreamRefBase(Stream) {}
104 
105 WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream,
106                                                  uint64_t Offset,
107                                                  std::optional<uint64_t> Length)
108     : BinaryStreamRefBase(Stream, Offset, Length) {}
109 
110 WritableBinaryStreamRef::WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
111                                                  endianness Endian)
112     : BinaryStreamRefBase(std::make_shared<MutableArrayRefImpl>(Data, Endian),
113                           0, Data.size()) {}
114 
115 Error WritableBinaryStreamRef::writeBytes(uint64_t Offset,
116                                           ArrayRef<uint8_t> Data) const {
117   if (auto EC = checkOffsetForWrite(Offset, Data.size()))
118     return EC;
119 
120   return BorrowedImpl->writeBytes(ViewOffset + Offset, Data);
121 }
122 
123 WritableBinaryStreamRef::operator BinaryStreamRef() const {
124   return BinaryStreamRef(*BorrowedImpl, ViewOffset, Length);
125 }
126 
127 /// For buffered streams, commits changes to the backing store.
128 Error WritableBinaryStreamRef::commit() { return BorrowedImpl->commit(); }
129