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                                  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(makeArrayRef(Data.bytes_begin(), Data.bytes_end()),
77                       Endian) {}
78 
79 Error BinaryStreamRef::readBytes(uint64_t Offset, uint64_t Size,
80                                  ArrayRef<uint8_t> &Buffer) const {
81   if (auto EC = checkOffsetForRead(Offset, Size))
82     return EC;
83   return BorrowedImpl->readBytes(ViewOffset + Offset, Size, Buffer);
84 }
85 
86 Error BinaryStreamRef::readLongestContiguousChunk(
87     uint64_t Offset, ArrayRef<uint8_t> &Buffer) const {
88   if (auto EC = checkOffsetForRead(Offset, 1))
89     return EC;
90 
91   if (auto EC =
92           BorrowedImpl->readLongestContiguousChunk(ViewOffset + Offset, Buffer))
93     return EC;
94   // This StreamRef might refer to a smaller window over a larger stream.  In
95   // that case we will have read out more bytes than we should return, because
96   // we should not read past the end of the current view.
97   uint64_t MaxLength = getLength() - Offset;
98   if (Buffer.size() > MaxLength)
99     Buffer = Buffer.slice(0, MaxLength);
100   return Error::success();
101 }
102 
103 WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream)
104     : BinaryStreamRefBase(Stream) {}
105 
106 WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream,
107                                                  uint64_t Offset,
108                                                  Optional<uint64_t> Length)
109     : BinaryStreamRefBase(Stream, Offset, Length) {}
110 
111 WritableBinaryStreamRef::WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
112                                                  endianness Endian)
113     : BinaryStreamRefBase(std::make_shared<MutableArrayRefImpl>(Data, Endian),
114                           0, Data.size()) {}
115 
116 Error WritableBinaryStreamRef::writeBytes(uint64_t Offset,
117                                           ArrayRef<uint8_t> Data) const {
118   if (auto EC = checkOffsetForWrite(Offset, Data.size()))
119     return EC;
120 
121   return BorrowedImpl->writeBytes(ViewOffset + Offset, Data);
122 }
123 
124 WritableBinaryStreamRef::operator BinaryStreamRef() const {
125   return BinaryStreamRef(*BorrowedImpl, ViewOffset, Length);
126 }
127 
128 /// For buffered streams, commits changes to the backing store.
129 Error WritableBinaryStreamRef::commit() { return BorrowedImpl->commit(); }
130