1 files changed, 179 insertions, 0 deletions
diff --git a/llvm/lib/Support/BinaryStreamReader.cpp b/llvm/lib/Support/BinaryStreamReader.cpp
new file mode 100644
index 0000000000000..b17786593bded
--- /dev/null
+++ b/llvm/lib/Support/BinaryStreamReader.cpp
@@ -0,0 +1,179 @@
+//===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryStreamReader.h"
+
+#include "llvm/Support/BinaryStreamError.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/LEB128.h"
+
+using namespace llvm;
+using endianness = llvm::support::endianness;
+
+BinaryStreamReader::BinaryStreamReader(BinaryStreamRef Ref) : Stream(Ref) {}
+
+BinaryStreamReader::BinaryStreamReader(BinaryStream &Stream) : Stream(Stream) {}
+
+BinaryStreamReader::BinaryStreamReader(ArrayRef<uint8_t> Data,
+                                       endianness Endian)
+    : Stream(Data, Endian) {}
+
+BinaryStreamReader::BinaryStreamReader(StringRef Data, endianness Endian)
+    : Stream(Data, Endian) {}
+
+Error BinaryStreamReader::readLongestContiguousChunk(
+    ArrayRef<uint8_t> &Buffer) {
+  if (auto EC = Stream.readLongestContiguousChunk(Offset, Buffer))
+    return EC;
+  Offset += Buffer.size();
+  return Error::success();
+}
+
+Error BinaryStreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) {
+  if (auto EC = Stream.readBytes(Offset, Size, Buffer))
+    return EC;
+  Offset += Size;
+  return Error::success();
+}
+
+Error BinaryStreamReader::readULEB128(uint64_t &Dest) {
+  SmallVector<uint8_t, 10> EncodedBytes;
+  ArrayRef<uint8_t> NextByte;
+
+  // Copy the encoded ULEB into the buffer.
+  do {
+    if (auto Err = readBytes(NextByte, 1))
+      return Err;
+    EncodedBytes.push_back(NextByte[0]);
+  } while (NextByte[0] & 0x80);
+
+  Dest = decodeULEB128(EncodedBytes.begin(), nullptr, EncodedBytes.end());
+  return Error::success();
+}
+
+Error BinaryStreamReader::readSLEB128(int64_t &Dest) {
+  SmallVector<uint8_t, 10> EncodedBytes;
+  ArrayRef<uint8_t> NextByte;
+
+  // Copy the encoded ULEB into the buffer.
+  do {
+    if (auto Err = readBytes(NextByte, 1))
+      return Err;
+    EncodedBytes.push_back(NextByte[0]);
+  } while (NextByte[0] & 0x80);
+
+  Dest = decodeSLEB128(EncodedBytes.begin(), nullptr, EncodedBytes.end());
+  return Error::success();
+}
+
+Error BinaryStreamReader::readCString(StringRef &Dest) {
+  uint32_t OriginalOffset = getOffset();
+  uint32_t FoundOffset = 0;
+  while (true) {
+    uint32_t ThisOffset = getOffset();
+    ArrayRef<uint8_t> Buffer;
+    if (auto EC = readLongestContiguousChunk(Buffer))
+      return EC;
+    StringRef S(reinterpret_cast<const char *>(Buffer.begin()), Buffer.size());
+    size_t Pos = S.find_first_of('\0');
+    if (LLVM_LIKELY(Pos != StringRef::npos)) {
+      FoundOffset = Pos + ThisOffset;
+      break;
+    }
+  }
+  assert(FoundOffset >= OriginalOffset);
+
+  setOffset(OriginalOffset);
+  size_t Length = FoundOffset - OriginalOffset;
+
+  if (auto EC = readFixedString(Dest, Length))
+    return EC;
+
+  // Now set the offset back to after the null terminator.
+  setOffset(FoundOffset + 1);
+  return Error::success();
+}
+
+Error BinaryStreamReader::readWideString(ArrayRef<UTF16> &Dest) {
+  uint32_t Length = 0;
+  uint32_t OriginalOffset = getOffset();
+  const UTF16 *C;
+  while (true) {
+    if (auto EC = readObject(C))
+      return EC;
+    if (*C == 0x0000)
+      break;
+    ++Length;
+  }
+  uint32_t NewOffset = getOffset();
+  setOffset(OriginalOffset);
+
+  if (auto EC = readArray(Dest, Length))
+    return EC;
+  setOffset(NewOffset);
+  return Error::success();
+}
+
+Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
+  ArrayRef<uint8_t> Bytes;
+  if (auto EC = readBytes(Bytes, Length))
+    return EC;
+  Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
+  return Error::success();
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) {
+  return readStreamRef(Ref, bytesRemaining());
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) {
+  if (bytesRemaining() < Length)
+    return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
+  Ref = Stream.slice(Offset, Length);
+  Offset += Length;
+  return Error::success();
+}
+
+Error BinaryStreamReader::readSubstream(BinarySubstreamRef &Stream,
+                                        uint32_t Size) {
+  Stream.Offset = getOffset();
+  return readStreamRef(Stream.StreamData, Size);
+}
+
+Error BinaryStreamReader::skip(uint32_t Amount) {
+  if (Amount > bytesRemaining())
+    return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
+  Offset += Amount;
+  return Error::success();
+}
+
+Error BinaryStreamReader::padToAlignment(uint32_t Align) {
+  uint32_t NewOffset = alignTo(Offset, Align);
+  return skip(NewOffset - Offset);
+}
+
+uint8_t BinaryStreamReader::peek() const {
+  ArrayRef<uint8_t> Buffer;
+  auto EC = Stream.readBytes(Offset, 1, Buffer);
+  assert(!EC && "Cannot peek an empty buffer!");
+  llvm::consumeError(std::move(EC));
+  return Buffer[0];
+}
+
+std::pair<BinaryStreamReader, BinaryStreamReader>
+BinaryStreamReader::split(uint32_t Off) const {
+  assert(getLength() >= Off);
+
+  BinaryStreamRef First = Stream.drop_front(Offset);
+
+  BinaryStreamRef Second = First.drop_front(Off);
+  First = First.keep_front(Off);
+  BinaryStreamReader W1{First};
+  BinaryStreamReader W2{Second};
+  return std::make_pair(W1, W2);
+}