6dedbcd5e9
While I think this is a performance improvement over the original, this actually fixes a correctness issue: For an appendable underlying stream, padToAlignment would fail if the additional padding would have caused the stream to grow since it was doing its own check on bounds. By deferring to the regular writeArray method this takes the same path as everything else, which does the correct bounds check in WritableBinaryStreamRef::checkOffsetForWrite (i.e. skips the extension check if BSF_Append is set). I had started to fix the existing bounds check in BinaryStreamWriter but deferred to this because it layered better and is more efficient/consistent. It didn't look like this method was tested at all, so I added a unit test. Differential Revision: https://reviews.llvm.org/D124746
105 lines
3.4 KiB
C++
105 lines
3.4 KiB
C++
//===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/BinaryStreamWriter.h"
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#include "llvm/Support/BinaryStreamError.h"
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#include "llvm/Support/BinaryStreamReader.h"
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#include "llvm/Support/BinaryStreamRef.h"
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#include "llvm/Support/LEB128.h"
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using namespace llvm;
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BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)
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: Stream(Ref) {}
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BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
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: Stream(Stream) {}
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BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
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llvm::support::endianness Endian)
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: Stream(Data, Endian) {}
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Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
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if (auto EC = Stream.writeBytes(Offset, Buffer))
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return EC;
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Offset += Buffer.size();
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return Error::success();
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}
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Error BinaryStreamWriter::writeULEB128(uint64_t Value) {
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uint8_t EncodedBytes[10] = {0};
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unsigned Size = encodeULEB128(Value, &EncodedBytes[0]);
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return writeBytes({EncodedBytes, Size});
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}
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Error BinaryStreamWriter::writeSLEB128(int64_t Value) {
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uint8_t EncodedBytes[10] = {0};
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unsigned Size = encodeSLEB128(Value, &EncodedBytes[0]);
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return writeBytes({EncodedBytes, Size});
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}
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Error BinaryStreamWriter::writeCString(StringRef Str) {
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if (auto EC = writeFixedString(Str))
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return EC;
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if (auto EC = writeObject('\0'))
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return EC;
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return Error::success();
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}
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Error BinaryStreamWriter::writeFixedString(StringRef Str) {
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return writeBytes(arrayRefFromStringRef(Str));
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}
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Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
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return writeStreamRef(Ref, Ref.getLength());
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}
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Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint64_t Length) {
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BinaryStreamReader SrcReader(Ref.slice(0, Length));
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// This is a bit tricky. If we just call readBytes, we are requiring that it
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// return us the entire stream as a contiguous buffer. There is no guarantee
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// this can be satisfied by returning a reference straight from the buffer, as
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// an implementation may not store all data in a single contiguous buffer. So
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// we iterate over each contiguous chunk, writing each one in succession.
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while (SrcReader.bytesRemaining() > 0) {
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ArrayRef<uint8_t> Chunk;
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if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
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return EC;
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if (auto EC = writeBytes(Chunk))
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return EC;
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}
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return Error::success();
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}
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std::pair<BinaryStreamWriter, BinaryStreamWriter>
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BinaryStreamWriter::split(uint64_t Off) const {
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assert(getLength() >= Off);
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WritableBinaryStreamRef First = Stream.drop_front(Offset);
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WritableBinaryStreamRef Second = First.drop_front(Off);
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First = First.keep_front(Off);
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BinaryStreamWriter W1{First};
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BinaryStreamWriter W2{Second};
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return std::make_pair(W1, W2);
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}
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Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
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uint64_t NewOffset = alignTo(Offset, Align);
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const uint64_t ZerosSize = 64;
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static constexpr char Zeros[ZerosSize] = {};
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while (Offset < NewOffset)
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if (auto E = writeArray(
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ArrayRef<char>(Zeros, std::min(ZerosSize, NewOffset - Offset))))
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return E;
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return Error::success();
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}
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