lib/Support/BinaryStreamWriter.cpp

   1 //===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/Support/BinaryStreamWriter.h"
  11
  12 #include "llvm/Support/BinaryStreamError.h"
  13 #include "llvm/Support/BinaryStreamReader.h"
  14 #include "llvm/Support/BinaryStreamRef.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::writeCString(StringRef Str) {
  36   if (auto EC = writeFixedString(Str))
  37     return EC;
  38   if (auto EC = writeObject('\0'))
  39     return EC;
  40
  41   return Error::success();
  42 }
  43
  44 Error BinaryStreamWriter::writeFixedString(StringRef Str) {
  45
  46   return writeBytes(arrayRefFromStringRef(Str));
  47 }
  48
  49 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
  50   return writeStreamRef(Ref, Ref.getLength());
  51 }
  52
  53 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
  54   BinaryStreamReader SrcReader(Ref.slice(0, Length));
  55   // This is a bit tricky.  If we just call readBytes, we are requiring that it
  56   // return us the entire stream as a contiguous buffer.  There is no guarantee
  57   // this can be satisfied by returning a reference straight from the buffer, as
  58   // an implementation may not store all data in a single contiguous buffer.  So
  59   // we iterate over each contiguous chunk, writing each one in succession.
  60   while (SrcReader.bytesRemaining() > 0) {
  61     ArrayRef<uint8_t> Chunk;
  62     if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
  63       return EC;
  64     if (auto EC = writeBytes(Chunk))
  65       return EC;
  66   }
  67   return Error::success();
  68 }
  69
  70 std::pair<BinaryStreamWriter, BinaryStreamWriter>
  71 BinaryStreamWriter::split(uint32_t Off) const {
  72   assert(getLength() >= Off);
  73
  74   WritableBinaryStreamRef First = Stream.drop_front(Offset);
  75
  76   WritableBinaryStreamRef Second = First.drop_front(Off);
  77   First = First.keep_front(Off);
  78   BinaryStreamWriter W1{First};
  79   BinaryStreamWriter W2{Second};
  80   return std::make_pair(W1, W2);
  81 }
  82
  83 Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
  84   uint32_t NewOffset = alignTo(Offset, Align);
  85   if (NewOffset > getLength())
  86     return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
  87   while (Offset < NewOffset)
  88     if (auto EC = writeInteger('\0'))
  89       return EC;
  90   return Error::success();
  91 }