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