lib/Support/BinaryStreamWriter.cpp

   1 //===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
   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/BinaryStreamWriter.h"
  10
  11 #include "llvm/Support/BinaryStreamError.h"
  12 #include "llvm/Support/BinaryStreamReader.h"
  13 #include "llvm/Support/BinaryStreamRef.h"
  14 #include "llvm/Support/LEB128.h"
  15
  16 using namespace llvm;
  17
  18 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)
  19     : Stream(Ref) {}
  20
  21 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
  22     : Stream(Stream) {}
  23
  24 BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
  25                                        llvm::support::endianness Endian)
  26     : Stream(Data, Endian) {}
  27
  28 Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
  29   if (auto EC = Stream.writeBytes(Offset, Buffer))
  30     return EC;
  31   Offset += Buffer.size();
  32   return Error::success();
  33 }
  34
  35 Error BinaryStreamWriter::writeULEB128(uint64_t Value) {
  36   uint8_t EncodedBytes[10] = {0};
  37   unsigned Size = encodeULEB128(Value, &EncodedBytes[0]);
  38   return writeBytes({EncodedBytes, Size});
  39 }
  40
  41 Error BinaryStreamWriter::writeSLEB128(int64_t Value) {
  42   uint8_t EncodedBytes[10] = {0};
  43   unsigned Size = encodeSLEB128(Value, &EncodedBytes[0]);
  44   return writeBytes({EncodedBytes, Size});
  45 }
  46
  47 Error BinaryStreamWriter::writeCString(StringRef Str) {
  48   if (auto EC = writeFixedString(Str))
  49     return EC;
  50   if (auto EC = writeObject('\0'))
  51     return EC;
  52
  53   return Error::success();
  54 }
  55
  56 Error BinaryStreamWriter::writeFixedString(StringRef Str) {
  57
  58   return writeBytes(arrayRefFromStringRef(Str));
  59 }
  60
  61 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
  62   return writeStreamRef(Ref, Ref.getLength());
  63 }
  64
  65 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
  66   BinaryStreamReader SrcReader(Ref.slice(0, Length));
  67   // This is a bit tricky.  If we just call readBytes, we are requiring that it
  68   // return us the entire stream as a contiguous buffer.  There is no guarantee
  69   // this can be satisfied by returning a reference straight from the buffer, as
  70   // an implementation may not store all data in a single contiguous buffer.  So
  71   // we iterate over each contiguous chunk, writing each one in succession.
  72   while (SrcReader.bytesRemaining() > 0) {
  73     ArrayRef<uint8_t> Chunk;
  74     if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
  75       return EC;
  76     if (auto EC = writeBytes(Chunk))
  77       return EC;
  78   }
  79   return Error::success();
  80 }
  81
  82 std::pair<BinaryStreamWriter, BinaryStreamWriter>
  83 BinaryStreamWriter::split(uint32_t Off) const {
  84   assert(getLength() >= Off);
  85
  86   WritableBinaryStreamRef First = Stream.drop_front(Offset);
  87
  88   WritableBinaryStreamRef Second = First.drop_front(Off);
  89   First = First.keep_front(Off);
  90   BinaryStreamWriter W1{First};
  91   BinaryStreamWriter W2{Second};
  92   return std::make_pair(W1, W2);
  93 }
  94
  95 Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
  96   uint32_t NewOffset = alignTo(Offset, Align);
  97   if (NewOffset > getLength())
  98     return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
  99   while (Offset < NewOffset)
 100     if (auto EC = writeInteger('\0'))
 101       return EC;
 102   return Error::success();
 103 }