108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
//===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/BinaryStreamReader.h"
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#include "llvm/Support/BinaryStreamError.h"
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#include "llvm/Support/BinaryStreamRef.h"
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using namespace llvm;
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BinaryStreamReader::BinaryStreamReader(BinaryStreamRef S)
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: Stream(S), Offset(0) {}
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Error BinaryStreamReader::readLongestContiguousChunk(
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ArrayRef<uint8_t> &Buffer) {
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if (auto EC = Stream.readLongestContiguousChunk(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 BinaryStreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) {
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if (auto EC = Stream.readBytes(Offset, Size, Buffer))
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return EC;
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Offset += Size;
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return Error::success();
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}
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Error BinaryStreamReader::readCString(StringRef &Dest) {
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// TODO: This could be made more efficient by using readLongestContiguousChunk
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// and searching for null terminators in the resulting buffer.
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uint32_t Length = 0;
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// First compute the length of the string by reading 1 byte at a time.
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uint32_t OriginalOffset = getOffset();
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const char *C;
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while (true) {
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if (auto EC = readObject(C))
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return EC;
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if (*C == '\0')
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break;
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++Length;
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}
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// Now go back and request a reference for that many bytes.
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uint32_t NewOffset = getOffset();
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setOffset(OriginalOffset);
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if (auto EC = readFixedString(Dest, Length))
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return EC;
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// Now set the offset back to where it was after we calculated the length.
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setOffset(NewOffset);
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return Error::success();
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}
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Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
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ArrayRef<uint8_t> Bytes;
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if (auto EC = readBytes(Bytes, Length))
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return EC;
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Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
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return Error::success();
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}
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Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) {
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return readStreamRef(Ref, bytesRemaining());
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}
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Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) {
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if (bytesRemaining() < Length)
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return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
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Ref = Stream.slice(Offset, Length);
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Offset += Length;
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return Error::success();
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}
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Error BinaryStreamReader::skip(uint32_t Amount) {
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if (Amount > bytesRemaining())
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return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
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Offset += Amount;
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return Error::success();
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}
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uint8_t BinaryStreamReader::peek() const {
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ArrayRef<uint8_t> Buffer;
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auto EC = Stream.readBytes(Offset, 1, Buffer);
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assert(!EC && "Cannot peek an empty buffer!");
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llvm::consumeError(std::move(EC));
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return Buffer[0];
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}
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std::pair<BinaryStreamReader, BinaryStreamReader>
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BinaryStreamReader::split(uint32_t Off) const {
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assert(getLength() >= Off);
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BinaryStreamRef First = Stream.drop_front(Offset);
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BinaryStreamRef Second = First.drop_front(Off);
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First = First.keep_front(Off);
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BinaryStreamReader W1{First};
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BinaryStreamReader W2{Second};
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return std::make_pair(W1, W2);
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} |