unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp - llvm - Git at Google

 //===- llvm/unittest/DebugInfo/MSF/MappedBlockStreamTest.cpp --------------===//
 //
 // 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/DebugInfo/MSF/MappedBlockStream.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Testing/Support/Error.h"

 #include "gmock/gmock.h"
 #include "gtest/gtest.h"


 using namespace llvm;
 using namespace llvm::msf;
 using namespace llvm::support;

 namespace {

 static const uint32_t BlocksAry[] = {0, 1, 2, 5, 4, 3, 6, 7, 8, 9};
 static uint8_t DataAry[] = {'A', 'B', 'C', 'F', 'E', 'D', 'G', 'H', 'I', 'J'};

 class DiscontiguousStream : public WritableBinaryStream {
 public:
   DiscontiguousStream(ArrayRef<uint32_t> Blocks, MutableArrayRef<uint8_t> Data)
       : Blocks(Blocks.begin(), Blocks.end()), Data(Data.begin(), Data.end()) {}

   uint32_t block_size() const { return 1; }
   uint32_t block_count() const { return Blocks.size(); }

   endianness getEndian() const override { return little; }

   Error readBytes(uint32_t Offset, uint32_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
     if (auto EC = checkOffsetForRead(Offset, Size))
       return EC;
     Buffer = Data.slice(Offset, Size);
     return Error::success();
   }

   Error readLongestContiguousChunk(uint32_t Offset,
                                    ArrayRef<uint8_t> &Buffer) override {
     if (auto EC = checkOffsetForRead(Offset, 1))
       return EC;
     Buffer = Data.drop_front(Offset);
     return Error::success();
   }

   uint32_t getLength() override { return Data.size(); }

   Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> SrcData) override {
     if (auto EC = checkOffsetForWrite(Offset, SrcData.size()))
       return EC;
     ::memcpy(&Data[Offset], SrcData.data(), SrcData.size());
     return Error::success();
   }
   Error commit() override { return Error::success(); }

   MSFStreamLayout layout() const {
     return MSFStreamLayout{static_cast<uint32_t>(Data.size()), Blocks};
   }

   BumpPtrAllocator Allocator;

 private:
   std::vector<support::ulittle32_t> Blocks;
   MutableArrayRef<uint8_t> Data;
 };

 TEST(MappedBlockStreamTest, NumBlocks) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   EXPECT_EQ(F.block_size(), S->getBlockSize());
   EXPECT_EQ(F.layout().Blocks.size(), S->getNumBlocks());
 }

 // Tests that a read which is entirely contained within a single block works
 // and does not allocate.
 TEST(MappedBlockStreamTest, ReadBeyondEndOfStreamRef) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);

   BinaryStreamReader R(*S);
   BinaryStreamRef SR;
   EXPECT_THAT_ERROR(R.readStreamRef(SR, 0U), Succeeded());
   ArrayRef<uint8_t> Buffer;
   EXPECT_THAT_ERROR(SR.readBytes(0U, 1U, Buffer), Failed());
   EXPECT_THAT_ERROR(R.readStreamRef(SR, 1U), Succeeded());
   EXPECT_THAT_ERROR(SR.readBytes(1U, 1U, Buffer), Failed());
 }

 // Tests that a read which outputs into a full destination buffer works and
 // does not fail due to the length of the output buffer.
 TEST(MappedBlockStreamTest, ReadOntoNonEmptyBuffer) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);

   BinaryStreamReader R(*S);
   StringRef Str = "ZYXWVUTSRQPONMLKJIHGFEDCBA";
   EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Succeeded());
   EXPECT_EQ(Str, StringRef("A"));
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Tests that a read which crosses a block boundary, but where the subsequent
 // blocks are still contiguous in memory to the previous block works and does
 // not allocate memory.
 TEST(MappedBlockStreamTest, ZeroCopyReadContiguousBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;
   EXPECT_THAT_ERROR(R.readFixedString(Str, 2), Succeeded());
   EXPECT_EQ(Str, StringRef("AB"));
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());

   R.setOffset(6);
   EXPECT_THAT_ERROR(R.readFixedString(Str, 4), Succeeded());
   EXPECT_EQ(Str, StringRef("GHIJ"));
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Tests that a read which crosses a block boundary and cannot be referenced
 // contiguously works and allocates only the precise amount of bytes
 // requested.
 TEST(MappedBlockStreamTest, CopyReadNonContiguousBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;
   EXPECT_THAT_ERROR(R.readFixedString(Str, 10), Succeeded());
   EXPECT_EQ(Str, StringRef("ABCDEFGHIJ"));
   EXPECT_EQ(10U, F.Allocator.getBytesAllocated());
 }

 // Test that an out of bounds read which doesn't cross a block boundary
 // fails and allocates no memory.
 TEST(MappedBlockStreamTest, InvalidReadSizeNoBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;

   R.setOffset(10);
   EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Failed());
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Test that an out of bounds read which crosses a contiguous block boundary
 // fails and allocates no memory.
 TEST(MappedBlockStreamTest, InvalidReadSizeContiguousBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;

   R.setOffset(6);
   EXPECT_THAT_ERROR(R.readFixedString(Str, 5), Failed());
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Test that an out of bounds read which crosses a discontiguous block
 // boundary fails and allocates no memory.
 TEST(MappedBlockStreamTest, InvalidReadSizeNonContiguousBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;

   EXPECT_THAT_ERROR(R.readFixedString(Str, 11), Failed());
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Tests that a read which is entirely contained within a single block but
 // beyond the end of a StreamRef fails.
 TEST(MappedBlockStreamTest, ZeroCopyReadNoBreak) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str;
   EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Succeeded());
   EXPECT_EQ(Str, StringRef("A"));
   EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
 }

 // Tests that a read which is not aligned on the same boundary as a previous
 // cached request, but which is known to overlap that request, shares the
 // previous allocation.
 TEST(MappedBlockStreamTest, UnalignedOverlappingRead) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str1;
   StringRef Str2;
   EXPECT_THAT_ERROR(R.readFixedString(Str1, 7), Succeeded());
   EXPECT_EQ(Str1, StringRef("ABCDEFG"));
   EXPECT_EQ(7U, F.Allocator.getBytesAllocated());

   R.setOffset(2);
   EXPECT_THAT_ERROR(R.readFixedString(Str2, 3), Succeeded());
   EXPECT_EQ(Str2, StringRef("CDE"));
   EXPECT_EQ(Str1.data() + 2, Str2.data());
   EXPECT_EQ(7U, F.Allocator.getBytesAllocated());
 }

 // Tests that a read which is not aligned on the same boundary as a previous
 // cached request, but which only partially overlaps a previous cached request,
 // still works correctly and allocates again from the shared pool.
 TEST(MappedBlockStreamTest, UnalignedOverlappingReadFail) {
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
                                            F.Allocator);
   BinaryStreamReader R(*S);
   StringRef Str1;
   StringRef Str2;
   EXPECT_THAT_ERROR(R.readFixedString(Str1, 6), Succeeded());
   EXPECT_EQ(Str1, StringRef("ABCDEF"));
   EXPECT_EQ(6U, F.Allocator.getBytesAllocated());

   R.setOffset(4);
   EXPECT_THAT_ERROR(R.readFixedString(Str2, 4), Succeeded());
   EXPECT_EQ(Str2, StringRef("EFGH"));
   EXPECT_EQ(10U, F.Allocator.getBytesAllocated());
 }

 TEST(MappedBlockStreamTest, WriteBeyondEndOfStream) {
   static uint8_t Data[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'};
   static uint8_t LargeBuffer[] = {'0', '1', '2', '3', '4', '5',
                                   '6', '7', '8', '9', 'A'};
   static uint8_t SmallBuffer[] = {'0', '1', '2'};
   static_assert(sizeof(LargeBuffer) > sizeof(Data),
                 "LargeBuffer is not big enough");

   DiscontiguousStream F(BlocksAry, Data);
   auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
                                                    F, F.Allocator);
   EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>(LargeBuffer)), Failed());
   EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>(SmallBuffer)),
                     Succeeded());
   EXPECT_THAT_ERROR(S->writeBytes(7, ArrayRef<uint8_t>(SmallBuffer)),
                     Succeeded());
   EXPECT_THAT_ERROR(S->writeBytes(8, ArrayRef<uint8_t>(SmallBuffer)), Failed());
 }

 TEST(MappedBlockStreamTest, TestWriteBytesNoBreakBoundary) {
   static uint8_t Data[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'};
   DiscontiguousStream F(BlocksAry, Data);
   auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
                                                    F, F.Allocator);
   ArrayRef<uint8_t> Buffer;

   EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));
   EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));

   EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>('J')), Succeeded());
   EXPECT_THAT_ERROR(S->writeBytes(9, ArrayRef<uint8_t>('A')), Succeeded());

   EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));
   EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));

   EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>('A')), Succeeded());
   EXPECT_THAT_ERROR(S->writeBytes(9, ArrayRef<uint8_t>('J')), Succeeded());

   EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));
   EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));
 }

 TEST(MappedBlockStreamTest, TestWriteBytesBreakBoundary) {
   static uint8_t Data[] = {'0', '0', '0', '0', '0', '0', '0', '0', '0', '0'};
   static uint8_t TestData[] = {'T', 'E', 'S', 'T', 'I', 'N', 'G', '.'};
   static uint8_t Expected[] = {'T', 'E', 'S', 'N', 'I',
                                'T', 'G', '.', '0', '0'};

   DiscontiguousStream F(BlocksAry, Data);
   auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
                                                    F, F.Allocator);
   ArrayRef<uint8_t> Buffer;

   EXPECT_THAT_ERROR(S->writeBytes(0, TestData), Succeeded());
   // First just compare the memory, then compare the result of reading the
   // string out.
   EXPECT_EQ(ArrayRef<uint8_t>(Data), ArrayRef<uint8_t>(Expected));

   EXPECT_THAT_ERROR(S->readBytes(0, 8, Buffer), Succeeded());
   EXPECT_EQ(Buffer, ArrayRef<uint8_t>(TestData));
 }

 TEST(MappedBlockStreamTest, TestWriteThenRead) {
   std::vector<uint8_t> DataBytes(10);
   MutableArrayRef<uint8_t> Data(DataBytes);
   const uint32_t Blocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

   DiscontiguousStream F(Blocks, Data);
   auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
                                                    F, F.Allocator);

   enum class MyEnum : uint32_t { Val1 = 2908234, Val2 = 120891234 };
   using support::ulittle32_t;

   uint16_t u16[] = {31468, 0};
   uint32_t u32[] = {890723408, 0};
   MyEnum Enum[] = {MyEnum::Val1, MyEnum::Val2};
   StringRef ZStr[] = {"Zero Str", ""};
   StringRef FStr[] = {"Fixed Str", ""};
   uint8_t byteArray0[] = {'1', '2'};
   uint8_t byteArray1[] = {'0', '0'};
   ArrayRef<uint8_t> byteArrayRef0(byteArray0);
   ArrayRef<uint8_t> byteArrayRef1(byteArray1);
   ArrayRef<uint8_t> byteArray[] = {byteArrayRef0, byteArrayRef1};
   uint32_t intArr0[] = {890723408, 29082234};
   uint32_t intArr1[] = {890723408, 29082234};
   ArrayRef<uint32_t> intArray[] = {intArr0, intArr1};

   BinaryStreamReader Reader(*S);
   BinaryStreamWriter Writer(*S);
   EXPECT_THAT_ERROR(Writer.writeInteger(u16[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readInteger(u16[1]), Succeeded());
   EXPECT_EQ(u16[0], u16[1]);
   EXPECT_EQ(std::vector<uint8_t>({0, 0x7A, 0xEC, 0, 0, 0, 0, 0, 0, 0}),
             DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeInteger(u32[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readInteger(u32[1]), Succeeded());
   EXPECT_EQ(u32[0], u32[1]);
   EXPECT_EQ(std::vector<uint8_t>({0x17, 0x5C, 0x50, 0, 0, 0, 0x35, 0, 0, 0}),
             DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeEnum(Enum[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readEnum(Enum[1]), Succeeded());
   EXPECT_EQ(Enum[0], Enum[1]);
   EXPECT_EQ(std::vector<uint8_t>({0x2C, 0x60, 0x4A, 0, 0, 0, 0, 0, 0, 0}),
             DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeCString(ZStr[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readCString(ZStr[1]), Succeeded());
   EXPECT_EQ(ZStr[0], ZStr[1]);
   EXPECT_EQ(
       std::vector<uint8_t>({'r', 'e', 'Z', ' ', 'S', 't', 'o', 'r', 0, 0}),
       DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeFixedString(FStr[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readFixedString(FStr[1], FStr[0].size()),
                     Succeeded());
   EXPECT_EQ(FStr[0], FStr[1]);
   EXPECT_EQ(
       std::vector<uint8_t>({'x', 'i', 'F', 'd', ' ', 'S', 'e', 't', 0, 'r'}),
       DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeArray(byteArray[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readArray(byteArray[1], byteArray[0].size()),
                     Succeeded());
   EXPECT_EQ(byteArray[0], byteArray[1]);
   EXPECT_EQ(std::vector<uint8_t>({0, 0x32, 0x31, 0, 0, 0, 0, 0, 0, 0}),
             DataBytes);

   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
   EXPECT_THAT_ERROR(Writer.writeArray(intArray[0]), Succeeded());
   EXPECT_THAT_ERROR(Reader.readArray(intArray[1], intArray[0].size()),
                     Succeeded());
   EXPECT_EQ(intArray[0], intArray[1]);
 }

 TEST(MappedBlockStreamTest, TestWriteContiguousStreamRef) {
   std::vector<uint8_t> DestDataBytes(10);
   MutableArrayRef<uint8_t> DestData(DestDataBytes);
   const uint32_t DestBlocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

   std::vector<uint8_t> SrcDataBytes(10);
   MutableArrayRef<uint8_t> SrcData(SrcDataBytes);

   DiscontiguousStream F(DestBlocks, DestData);
   auto DestStream = WritableMappedBlockStream::createStream(
       F.block_size(), F.layout(), F, F.Allocator);

   // First write "Test Str" into the source stream.
   MutableBinaryByteStream SourceStream(SrcData, little);
   BinaryStreamWriter SourceWriter(SourceStream);
   EXPECT_THAT_ERROR(SourceWriter.writeCString("Test Str"), Succeeded());
   EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
                               {'T', 'e', 's', 't', ' ', 'S', 't', 'r', 0, 0}));

   // Then write the source stream into the dest stream.
   BinaryStreamWriter DestWriter(*DestStream);
   EXPECT_THAT_ERROR(DestWriter.writeStreamRef(SourceStream), Succeeded());
   EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
                                {'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));

   // Then read the string back out of the dest stream.
   StringRef Result;
   BinaryStreamReader DestReader(*DestStream);
   EXPECT_THAT_ERROR(DestReader.readCString(Result), Succeeded());
   EXPECT_EQ(Result, "Test Str");
 }

 TEST(MappedBlockStreamTest, TestWriteDiscontiguousStreamRef) {
   std::vector<uint8_t> DestDataBytes(10);
   MutableArrayRef<uint8_t> DestData(DestDataBytes);
   const uint32_t DestBlocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

   std::vector<uint8_t> SrcDataBytes(10);
   MutableArrayRef<uint8_t> SrcData(SrcDataBytes);
   const uint32_t SrcBlocks[] = {1, 0, 6, 3, 4, 5, 2, 7, 8, 9};

   DiscontiguousStream DestF(DestBlocks, DestData);
   DiscontiguousStream SrcF(SrcBlocks, SrcData);

   auto Dest = WritableMappedBlockStream::createStream(
       DestF.block_size(), DestF.layout(), DestF, DestF.Allocator);
   auto Src = WritableMappedBlockStream::createStream(
       SrcF.block_size(), SrcF.layout(), SrcF, SrcF.Allocator);

   // First write "Test Str" into the source stream.
   BinaryStreamWriter SourceWriter(*Src);
   EXPECT_THAT_ERROR(SourceWriter.writeCString("Test Str"), Succeeded());
   EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
                               {'e', 'T', 't', 't', ' ', 'S', 's', 'r', 0, 0}));

   // Then write the source stream into the dest stream.
   BinaryStreamWriter DestWriter(*Dest);
   EXPECT_THAT_ERROR(DestWriter.writeStreamRef(*Src), Succeeded());
   EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
                                {'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));

   // Then read the string back out of the dest stream.
   StringRef Result;
   BinaryStreamReader DestReader(*Dest);
   EXPECT_THAT_ERROR(DestReader.readCString(Result), Succeeded());
   EXPECT_EQ(Result, "Test Str");
 }

 TEST(MappedBlockStreamTest, DataLivesAfterStreamDestruction) {
   std::vector<uint8_t> DataBytes(10);
   MutableArrayRef<uint8_t> Data(DataBytes);
   const uint32_t Blocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

   StringRef Str[] = {"Zero Str", ""};

   DiscontiguousStream F(Blocks, Data);
   {
     auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
                                                      F, F.Allocator);

     BinaryStreamReader Reader(*S);
     BinaryStreamWriter Writer(*S);
     ::memset(DataBytes.data(), 0, 10);
     EXPECT_THAT_ERROR(Writer.writeCString(Str[0]), Succeeded());
     EXPECT_THAT_ERROR(Reader.readCString(Str[1]), Succeeded());
     EXPECT_EQ(Str[0], Str[1]);
   }

   EXPECT_EQ(Str[0], Str[1]);
 }
 } // namespace

 MATCHER_P3(BlockIsFilledWith, Layout, BlockIndex, Byte, "succeeded") {
   uint64_t Offset = msf::blockToOffset(BlockIndex, Layout.SB->BlockSize);
   ArrayRef<uint8_t> BufferRef = makeArrayRef(arg);
   BufferRef = BufferRef.slice(Offset, Layout.SB->BlockSize);
   return llvm::all_of(BufferRef, [this](uint8_t B) { return B == Byte; });
 }

 namespace {
 TEST(MappedBlockStreamTest, CreateFpmStream) {
   BumpPtrAllocator Allocator;
   SuperBlock SB;
   MSFLayout L;
   L.SB = &SB;

   SB.FreeBlockMapBlock = 1;
   SB.BlockSize = 4096;

   constexpr uint32_t NumFileBlocks = 4096 * 4;

   std::vector<uint8_t> MsfBuffer(NumFileBlocks * SB.BlockSize);
   MutableBinaryByteStream MsfStream(MsfBuffer, llvm::support::little);

   SB.NumBlocks = NumFileBlocks;
   auto FpmStream =
       WritableMappedBlockStream::createFpmStream(L, MsfStream, Allocator);
   // 4096 * 4 / 8 = 2048 bytes of FPM data is needed to describe 4096 * 4
   // blocks.  This translates to 1 FPM block.
   EXPECT_EQ(2048u, FpmStream->getLength());
   EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks.size());
   EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks[0]);
   // All blocks from FPM1 should be 1 initialized, and all blocks from FPM2
   // should be 0 initialized (since we requested the main FPM, not the alt FPM)
   for (int I = 0; I < 4; ++I) {
     EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 1 + I * SB.BlockSize, 0xFF));
     EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 2 + I * SB.BlockSize, 0));
   }

   ::memset(MsfBuffer.data(), 0, MsfBuffer.size());
   FpmStream =
       WritableMappedBlockStream::createFpmStream(L, MsfStream, Allocator, true);
   // 4096 * 4 / 8 = 2048 bytes of FPM data is needed to describe 4096 * 4
   // blocks.  This translates to 1 FPM block.
   EXPECT_EQ(2048u, FpmStream->getLength());
   EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks.size());
   EXPECT_EQ(2u, FpmStream->getStreamLayout().Blocks[0]);
   // All blocks from FPM2 should be 1 initialized, and all blocks from FPM1
   // should be 0 initialized (since we requested the alt FPM, not the main FPM)
   for (int I = 0; I < 4; ++I) {
     EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 1 + I * SB.BlockSize, 0));
     EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 2 + I * SB.BlockSize, 0xFF));
   }
 }

 } // end anonymous namespace
	//===- llvm/unittest/DebugInfo/MSF/MappedBlockStreamTest.cpp --------------===//
	//
	// 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/DebugInfo/MSF/MappedBlockStream.h"
	#include "llvm/Support/BinaryByteStream.h"
	#include "llvm/Support/BinaryStreamReader.h"
	#include "llvm/Support/BinaryStreamRef.h"
	#include "llvm/Support/BinaryStreamWriter.h"
	#include "llvm/Testing/Support/Error.h"

	#include "gmock/gmock.h"
	#include "gtest/gtest.h"


	using namespace llvm;
	using namespace llvm::msf;
	using namespace llvm::support;

	namespace {

	static const uint32_t BlocksAry[] = {0, 1, 2, 5, 4, 3, 6, 7, 8, 9};
	static uint8_t DataAry[] = {'A', 'B', 'C', 'F', 'E', 'D', 'G', 'H', 'I', 'J'};

	class DiscontiguousStream : public WritableBinaryStream {
	public:
	DiscontiguousStream(ArrayRef<uint32_t> Blocks, MutableArrayRef<uint8_t> Data)
	: Blocks(Blocks.begin(), Blocks.end()), Data(Data.begin(), Data.end()) {}

	uint32_t block_size() const { return 1; }
	uint32_t block_count() const { return Blocks.size(); }

	endianness getEndian() const override { return little; }

	Error readBytes(uint32_t Offset, uint32_t Size,
	ArrayRef<uint8_t> &Buffer) override {
	if (auto EC = checkOffsetForRead(Offset, Size))
	return EC;
	Buffer = Data.slice(Offset, Size);
	return Error::success();
	}

	Error readLongestContiguousChunk(uint32_t Offset,
	ArrayRef<uint8_t> &Buffer) override {
	if (auto EC = checkOffsetForRead(Offset, 1))
	return EC;
	Buffer = Data.drop_front(Offset);
	return Error::success();
	}

	uint32_t getLength() override { return Data.size(); }

	Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> SrcData) override {
	if (auto EC = checkOffsetForWrite(Offset, SrcData.size()))
	return EC;
	::memcpy(&Data[Offset], SrcData.data(), SrcData.size());
	return Error::success();
	}
	Error commit() override { return Error::success(); }

	MSFStreamLayout layout() const {
	return MSFStreamLayout{static_cast<uint32_t>(Data.size()), Blocks};
	}

	BumpPtrAllocator Allocator;

	private:
	std::vector<support::ulittle32_t> Blocks;
	MutableArrayRef<uint8_t> Data;
	};

	TEST(MappedBlockStreamTest, NumBlocks) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	EXPECT_EQ(F.block_size(), S->getBlockSize());
	EXPECT_EQ(F.layout().Blocks.size(), S->getNumBlocks());
	}

	// Tests that a read which is entirely contained within a single block works
	// and does not allocate.
	TEST(MappedBlockStreamTest, ReadBeyondEndOfStreamRef) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);

	BinaryStreamReader R(*S);
	BinaryStreamRef SR;
	EXPECT_THAT_ERROR(R.readStreamRef(SR, 0U), Succeeded());
	ArrayRef<uint8_t> Buffer;
	EXPECT_THAT_ERROR(SR.readBytes(0U, 1U, Buffer), Failed());
	EXPECT_THAT_ERROR(R.readStreamRef(SR, 1U), Succeeded());
	EXPECT_THAT_ERROR(SR.readBytes(1U, 1U, Buffer), Failed());
	}

	// Tests that a read which outputs into a full destination buffer works and
	// does not fail due to the length of the output buffer.
	TEST(MappedBlockStreamTest, ReadOntoNonEmptyBuffer) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);

	BinaryStreamReader R(*S);
	StringRef Str = "ZYXWVUTSRQPONMLKJIHGFEDCBA";
	EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Succeeded());
	EXPECT_EQ(Str, StringRef("A"));
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Tests that a read which crosses a block boundary, but where the subsequent
	// blocks are still contiguous in memory to the previous block works and does
	// not allocate memory.
	TEST(MappedBlockStreamTest, ZeroCopyReadContiguousBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;
	EXPECT_THAT_ERROR(R.readFixedString(Str, 2), Succeeded());
	EXPECT_EQ(Str, StringRef("AB"));
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());

	R.setOffset(6);
	EXPECT_THAT_ERROR(R.readFixedString(Str, 4), Succeeded());
	EXPECT_EQ(Str, StringRef("GHIJ"));
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Tests that a read which crosses a block boundary and cannot be referenced
	// contiguously works and allocates only the precise amount of bytes
	// requested.
	TEST(MappedBlockStreamTest, CopyReadNonContiguousBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;
	EXPECT_THAT_ERROR(R.readFixedString(Str, 10), Succeeded());
	EXPECT_EQ(Str, StringRef("ABCDEFGHIJ"));
	EXPECT_EQ(10U, F.Allocator.getBytesAllocated());
	}

	// Test that an out of bounds read which doesn't cross a block boundary
	// fails and allocates no memory.
	TEST(MappedBlockStreamTest, InvalidReadSizeNoBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;

	R.setOffset(10);
	EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Failed());
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Test that an out of bounds read which crosses a contiguous block boundary
	// fails and allocates no memory.
	TEST(MappedBlockStreamTest, InvalidReadSizeContiguousBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;

	R.setOffset(6);
	EXPECT_THAT_ERROR(R.readFixedString(Str, 5), Failed());
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Test that an out of bounds read which crosses a discontiguous block
	// boundary fails and allocates no memory.
	TEST(MappedBlockStreamTest, InvalidReadSizeNonContiguousBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;

	EXPECT_THAT_ERROR(R.readFixedString(Str, 11), Failed());
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Tests that a read which is entirely contained within a single block but
	// beyond the end of a StreamRef fails.
	TEST(MappedBlockStreamTest, ZeroCopyReadNoBreak) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str;
	EXPECT_THAT_ERROR(R.readFixedString(Str, 1), Succeeded());
	EXPECT_EQ(Str, StringRef("A"));
	EXPECT_EQ(0U, F.Allocator.getBytesAllocated());
	}

	// Tests that a read which is not aligned on the same boundary as a previous
	// cached request, but which is known to overlap that request, shares the
	// previous allocation.
	TEST(MappedBlockStreamTest, UnalignedOverlappingRead) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str1;
	StringRef Str2;
	EXPECT_THAT_ERROR(R.readFixedString(Str1, 7), Succeeded());
	EXPECT_EQ(Str1, StringRef("ABCDEFG"));
	EXPECT_EQ(7U, F.Allocator.getBytesAllocated());

	R.setOffset(2);
	EXPECT_THAT_ERROR(R.readFixedString(Str2, 3), Succeeded());
	EXPECT_EQ(Str2, StringRef("CDE"));
	EXPECT_EQ(Str1.data() + 2, Str2.data());
	EXPECT_EQ(7U, F.Allocator.getBytesAllocated());
	}

	// Tests that a read which is not aligned on the same boundary as a previous
	// cached request, but which only partially overlaps a previous cached request,
	// still works correctly and allocates again from the shared pool.
	TEST(MappedBlockStreamTest, UnalignedOverlappingReadFail) {
	DiscontiguousStream F(BlocksAry, DataAry);
	auto S = MappedBlockStream::createStream(F.block_size(), F.layout(), F,
	F.Allocator);
	BinaryStreamReader R(*S);
	StringRef Str1;
	StringRef Str2;
	EXPECT_THAT_ERROR(R.readFixedString(Str1, 6), Succeeded());
	EXPECT_EQ(Str1, StringRef("ABCDEF"));
	EXPECT_EQ(6U, F.Allocator.getBytesAllocated());

	R.setOffset(4);
	EXPECT_THAT_ERROR(R.readFixedString(Str2, 4), Succeeded());
	EXPECT_EQ(Str2, StringRef("EFGH"));
	EXPECT_EQ(10U, F.Allocator.getBytesAllocated());
	}

	TEST(MappedBlockStreamTest, WriteBeyondEndOfStream) {
	static uint8_t Data[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'};
	static uint8_t LargeBuffer[] = {'0', '1', '2', '3', '4', '5',
	'6', '7', '8', '9', 'A'};
	static uint8_t SmallBuffer[] = {'0', '1', '2'};
	static_assert(sizeof(LargeBuffer) > sizeof(Data),
	"LargeBuffer is not big enough");

	DiscontiguousStream F(BlocksAry, Data);
	auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
	F, F.Allocator);
	EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>(LargeBuffer)), Failed());
	EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>(SmallBuffer)),
	Succeeded());
	EXPECT_THAT_ERROR(S->writeBytes(7, ArrayRef<uint8_t>(SmallBuffer)),
	Succeeded());
	EXPECT_THAT_ERROR(S->writeBytes(8, ArrayRef<uint8_t>(SmallBuffer)), Failed());
	}

	TEST(MappedBlockStreamTest, TestWriteBytesNoBreakBoundary) {
	static uint8_t Data[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'};
	DiscontiguousStream F(BlocksAry, Data);
	auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
	F, F.Allocator);
	ArrayRef<uint8_t> Buffer;

	EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));
	EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));

	EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>('J')), Succeeded());
	EXPECT_THAT_ERROR(S->writeBytes(9, ArrayRef<uint8_t>('A')), Succeeded());

	EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));
	EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));

	EXPECT_THAT_ERROR(S->writeBytes(0, ArrayRef<uint8_t>('A')), Succeeded());
	EXPECT_THAT_ERROR(S->writeBytes(9, ArrayRef<uint8_t>('J')), Succeeded());

	EXPECT_THAT_ERROR(S->readBytes(0, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('A'));
	EXPECT_THAT_ERROR(S->readBytes(9, 1, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>('J'));
	}

	TEST(MappedBlockStreamTest, TestWriteBytesBreakBoundary) {
	static uint8_t Data[] = {'0', '0', '0', '0', '0', '0', '0', '0', '0', '0'};
	static uint8_t TestData[] = {'T', 'E', 'S', 'T', 'I', 'N', 'G', '.'};
	static uint8_t Expected[] = {'T', 'E', 'S', 'N', 'I',
	'T', 'G', '.', '0', '0'};

	DiscontiguousStream F(BlocksAry, Data);
	auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
	F, F.Allocator);
	ArrayRef<uint8_t> Buffer;

	EXPECT_THAT_ERROR(S->writeBytes(0, TestData), Succeeded());
	// First just compare the memory, then compare the result of reading the
	// string out.
	EXPECT_EQ(ArrayRef<uint8_t>(Data), ArrayRef<uint8_t>(Expected));

	EXPECT_THAT_ERROR(S->readBytes(0, 8, Buffer), Succeeded());
	EXPECT_EQ(Buffer, ArrayRef<uint8_t>(TestData));
	}

	TEST(MappedBlockStreamTest, TestWriteThenRead) {
	std::vector<uint8_t> DataBytes(10);
	MutableArrayRef<uint8_t> Data(DataBytes);
	const uint32_t Blocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

	DiscontiguousStream F(Blocks, Data);
	auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
	F, F.Allocator);

	enum class MyEnum : uint32_t { Val1 = 2908234, Val2 = 120891234 };
	using support::ulittle32_t;

	uint16_t u16[] = {31468, 0};
	uint32_t u32[] = {890723408, 0};
	MyEnum Enum[] = {MyEnum::Val1, MyEnum::Val2};
	StringRef ZStr[] = {"Zero Str", ""};
	StringRef FStr[] = {"Fixed Str", ""};
	uint8_t byteArray0[] = {'1', '2'};
	uint8_t byteArray1[] = {'0', '0'};
	ArrayRef<uint8_t> byteArrayRef0(byteArray0);
	ArrayRef<uint8_t> byteArrayRef1(byteArray1);
	ArrayRef<uint8_t> byteArray[] = {byteArrayRef0, byteArrayRef1};
	uint32_t intArr0[] = {890723408, 29082234};
	uint32_t intArr1[] = {890723408, 29082234};
	ArrayRef<uint32_t> intArray[] = {intArr0, intArr1};

	BinaryStreamReader Reader(*S);
	BinaryStreamWriter Writer(*S);
	EXPECT_THAT_ERROR(Writer.writeInteger(u16[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readInteger(u16[1]), Succeeded());
	EXPECT_EQ(u16[0], u16[1]);
	EXPECT_EQ(std::vector<uint8_t>({0, 0x7A, 0xEC, 0, 0, 0, 0, 0, 0, 0}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeInteger(u32[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readInteger(u32[1]), Succeeded());
	EXPECT_EQ(u32[0], u32[1]);
	EXPECT_EQ(std::vector<uint8_t>({0x17, 0x5C, 0x50, 0, 0, 0, 0x35, 0, 0, 0}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeEnum(Enum[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readEnum(Enum[1]), Succeeded());
	EXPECT_EQ(Enum[0], Enum[1]);
	EXPECT_EQ(std::vector<uint8_t>({0x2C, 0x60, 0x4A, 0, 0, 0, 0, 0, 0, 0}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeCString(ZStr[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readCString(ZStr[1]), Succeeded());
	EXPECT_EQ(ZStr[0], ZStr[1]);
	EXPECT_EQ(
	std::vector<uint8_t>({'r', 'e', 'Z', ' ', 'S', 't', 'o', 'r', 0, 0}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeFixedString(FStr[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readFixedString(FStr[1], FStr[0].size()),
	Succeeded());
	EXPECT_EQ(FStr[0], FStr[1]);
	EXPECT_EQ(
	std::vector<uint8_t>({'x', 'i', 'F', 'd', ' ', 'S', 'e', 't', 0, 'r'}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeArray(byteArray[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readArray(byteArray[1], byteArray[0].size()),
	Succeeded());
	EXPECT_EQ(byteArray[0], byteArray[1]);
	EXPECT_EQ(std::vector<uint8_t>({0, 0x32, 0x31, 0, 0, 0, 0, 0, 0, 0}),
	DataBytes);

	Reader.setOffset(0);
	Writer.setOffset(0);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeArray(intArray[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readArray(intArray[1], intArray[0].size()),
	Succeeded());
	EXPECT_EQ(intArray[0], intArray[1]);
	}

	TEST(MappedBlockStreamTest, TestWriteContiguousStreamRef) {
	std::vector<uint8_t> DestDataBytes(10);
	MutableArrayRef<uint8_t> DestData(DestDataBytes);
	const uint32_t DestBlocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

	std::vector<uint8_t> SrcDataBytes(10);
	MutableArrayRef<uint8_t> SrcData(SrcDataBytes);

	DiscontiguousStream F(DestBlocks, DestData);
	auto DestStream = WritableMappedBlockStream::createStream(
	F.block_size(), F.layout(), F, F.Allocator);

	// First write "Test Str" into the source stream.
	MutableBinaryByteStream SourceStream(SrcData, little);
	BinaryStreamWriter SourceWriter(SourceStream);
	EXPECT_THAT_ERROR(SourceWriter.writeCString("Test Str"), Succeeded());
	EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
	{'T', 'e', 's', 't', ' ', 'S', 't', 'r', 0, 0}));

	// Then write the source stream into the dest stream.
	BinaryStreamWriter DestWriter(*DestStream);
	EXPECT_THAT_ERROR(DestWriter.writeStreamRef(SourceStream), Succeeded());
	EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
	{'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));

	// Then read the string back out of the dest stream.
	StringRef Result;
	BinaryStreamReader DestReader(*DestStream);
	EXPECT_THAT_ERROR(DestReader.readCString(Result), Succeeded());
	EXPECT_EQ(Result, "Test Str");
	}

	TEST(MappedBlockStreamTest, TestWriteDiscontiguousStreamRef) {
	std::vector<uint8_t> DestDataBytes(10);
	MutableArrayRef<uint8_t> DestData(DestDataBytes);
	const uint32_t DestBlocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

	std::vector<uint8_t> SrcDataBytes(10);
	MutableArrayRef<uint8_t> SrcData(SrcDataBytes);
	const uint32_t SrcBlocks[] = {1, 0, 6, 3, 4, 5, 2, 7, 8, 9};

	DiscontiguousStream DestF(DestBlocks, DestData);
	DiscontiguousStream SrcF(SrcBlocks, SrcData);

	auto Dest = WritableMappedBlockStream::createStream(
	DestF.block_size(), DestF.layout(), DestF, DestF.Allocator);
	auto Src = WritableMappedBlockStream::createStream(
	SrcF.block_size(), SrcF.layout(), SrcF, SrcF.Allocator);

	// First write "Test Str" into the source stream.
	BinaryStreamWriter SourceWriter(*Src);
	EXPECT_THAT_ERROR(SourceWriter.writeCString("Test Str"), Succeeded());
	EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
	{'e', 'T', 't', 't', ' ', 'S', 's', 'r', 0, 0}));

	// Then write the source stream into the dest stream.
	BinaryStreamWriter DestWriter(*Dest);
	EXPECT_THAT_ERROR(DestWriter.writeStreamRef(*Src), Succeeded());
	EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
	{'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));

	// Then read the string back out of the dest stream.
	StringRef Result;
	BinaryStreamReader DestReader(*Dest);
	EXPECT_THAT_ERROR(DestReader.readCString(Result), Succeeded());
	EXPECT_EQ(Result, "Test Str");
	}

	TEST(MappedBlockStreamTest, DataLivesAfterStreamDestruction) {
	std::vector<uint8_t> DataBytes(10);
	MutableArrayRef<uint8_t> Data(DataBytes);
	const uint32_t Blocks[] = {2, 1, 0, 6, 3, 4, 5, 7, 9, 8};

	StringRef Str[] = {"Zero Str", ""};

	DiscontiguousStream F(Blocks, Data);
	{
	auto S = WritableMappedBlockStream::createStream(F.block_size(), F.layout(),
	F, F.Allocator);

	BinaryStreamReader Reader(*S);
	BinaryStreamWriter Writer(*S);
	::memset(DataBytes.data(), 0, 10);
	EXPECT_THAT_ERROR(Writer.writeCString(Str[0]), Succeeded());
	EXPECT_THAT_ERROR(Reader.readCString(Str[1]), Succeeded());
	EXPECT_EQ(Str[0], Str[1]);
	}

	EXPECT_EQ(Str[0], Str[1]);
	}
	} // namespace

	MATCHER_P3(BlockIsFilledWith, Layout, BlockIndex, Byte, "succeeded") {
	uint64_t Offset = msf::blockToOffset(BlockIndex, Layout.SB->BlockSize);
	ArrayRef<uint8_t> BufferRef = makeArrayRef(arg);
	BufferRef = BufferRef.slice(Offset, Layout.SB->BlockSize);
	return llvm::all_of(BufferRef, [this](uint8_t B) { return B == Byte; });
	}

	namespace {
	TEST(MappedBlockStreamTest, CreateFpmStream) {
	BumpPtrAllocator Allocator;
	SuperBlock SB;
	MSFLayout L;
	L.SB = &SB;

	SB.FreeBlockMapBlock = 1;
	SB.BlockSize = 4096;

	constexpr uint32_t NumFileBlocks = 4096 * 4;

	std::vector<uint8_t> MsfBuffer(NumFileBlocks * SB.BlockSize);
	MutableBinaryByteStream MsfStream(MsfBuffer, llvm::support::little);

	SB.NumBlocks = NumFileBlocks;
	auto FpmStream =
	WritableMappedBlockStream::createFpmStream(L, MsfStream, Allocator);
	// 4096 * 4 / 8 = 2048 bytes of FPM data is needed to describe 4096 * 4
	// blocks. This translates to 1 FPM block.
	EXPECT_EQ(2048u, FpmStream->getLength());
	EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks.size());
	EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks[0]);
	// All blocks from FPM1 should be 1 initialized, and all blocks from FPM2
	// should be 0 initialized (since we requested the main FPM, not the alt FPM)
	for (int I = 0; I < 4; ++I) {
	EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 1 + I * SB.BlockSize, 0xFF));
	EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 2 + I * SB.BlockSize, 0));
	}

	::memset(MsfBuffer.data(), 0, MsfBuffer.size());
	FpmStream =
	WritableMappedBlockStream::createFpmStream(L, MsfStream, Allocator, true);
	// 4096 * 4 / 8 = 2048 bytes of FPM data is needed to describe 4096 * 4
	// blocks. This translates to 1 FPM block.
	EXPECT_EQ(2048u, FpmStream->getLength());
	EXPECT_EQ(1u, FpmStream->getStreamLayout().Blocks.size());
	EXPECT_EQ(2u, FpmStream->getStreamLayout().Blocks[0]);
	// All blocks from FPM2 should be 1 initialized, and all blocks from FPM1
	// should be 0 initialized (since we requested the alt FPM, not the main FPM)
	for (int I = 0; I < 4; ++I) {
	EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 1 + I * SB.BlockSize, 0));
	EXPECT_THAT(MsfBuffer, BlockIsFilledWith(L, 2 + I * SB.BlockSize, 0xFF));
	}
	}

	} // end anonymous namespace