//===- SerializedDiagnosticReader.cpp - Reads diagnostics -----------------===//

//

// 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 "clang/Frontend/SerializedDiagnosticReader.h"

#include "clang/Basic/FileManager.h"

#include "clang/Basic/FileSystemOptions.h"

#include "clang/Frontend/SerializedDiagnostics.h"

#include "llvm/ADT/Optional.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/Bitstream/BitCodes.h"

#include "llvm/Bitstream/BitstreamReader.h"

#include "llvm/Support/Compiler.h"

#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/ErrorOr.h"

#include "llvm/Support/ManagedStatic.h"

#include <cstdint>

#include <system_error>

using namespace clang;

using namespace serialized_diags;

std::error_code SerializedDiagnosticReader::readDiagnostics(StringRef File) {

  // Open the diagnostics file.

  FileSystemOptions FO;

  FileManager FileMgr(FO);

  auto Buffer = FileMgr.getBufferForFile(File);

  if (!Buffer)

    return SDError::CouldNotLoad;

  llvm::BitstreamCursor Stream(**Buffer);

  Optional<llvm::BitstreamBlockInfo> BlockInfo;

  if (Stream.AtEndOfStream())

    return SDError::InvalidSignature;

  // Sniff for the signature.

  
for (unsigned char C : {'D', 'I', 'A', 'G'})15
 {

    if (Expected<llvm::SimpleBitstreamCursor::word_t> Res = Stream.Read(8)) {

      if (Res.get() == C)

        continue;

    } else {

      // FIXME this drops the error on the floor.

      consumeError(Res.takeError());

    }

    return SDError::InvalidSignature;

  }

  // Read the top level blocks.

  
while (15
!Stream.AtEndOfStream()) {

    if (Expected<unsigned> Res = Stream.ReadCode()) {

      if (Res.get() != llvm::bitc::ENTER_SUBBLOCK)

        return SDError::InvalidDiagnostics;

    } else {

      // FIXME this drops the error on the floor.

      consumeError(Res.takeError());

      return SDError::InvalidDiagnostics;

    }

    std::error_code EC;

    Expected<unsigned> MaybeSubBlockID = Stream.ReadSubBlockID();

    if (!MaybeSubBlockID) {

      // FIXME this drops the error on the floor.

      consumeError(MaybeSubBlockID.takeError());

      return SDError::InvalidDiagnostics;

    }

    switch (MaybeSubBlockID.get()) {

    case llvm::bitc::BLOCKINFO_BLOCK_ID: {

      Expected<Optional<llvm::BitstreamBlockInfo>> MaybeBlockInfo =

          Stream.ReadBlockInfoBlock();

      if (!MaybeBlockInfo) {

        // FIXME this drops the error on the floor.

        consumeError(MaybeBlockInfo.takeError());

        return SDError::InvalidDiagnostics;

      }

      BlockInfo = std::move(MaybeBlockInfo.get());

    }

      if (!BlockInfo)

        return SDError::MalformedBlockInfoBlock;

      Stream.setBlockInfo(&*BlockInfo);

      continue;

    case BLOCK_META:

      if ((EC = readMetaBlock(Stream)))

        return EC;

      continue;

    case BLOCK_DIAG:

      if ((EC = readDiagnosticBlock(Stream)))

        return EC;

      continue;

    default:

      if (llvm::Error Err = Stream.SkipBlock()) {

        // FIXME this drops the error on the floor.

        consumeError(std::move(Err));

        return SDError::MalformedTopLevelBlock;

      }

      continue;

    }

  }

  return {};

}

enum class SerializedDiagnosticReader::Cursor {

  Record = 1,

  BlockEnd,

  BlockBegin

};

llvm::ErrorOr<SerializedDiagnosticReader::Cursor>

SerializedDiagnosticReader::skipUntilRecordOrBlock(

    llvm::BitstreamCursor &Stream, unsigned &BlockOrRecordID) {

  BlockOrRecordID = 0;

  while (!Stream.AtEndOfStream()) {

    unsigned Code;

    if (Expected<unsigned> Res = Stream.ReadCode())

      Code = Res.get();

    else

      return llvm::errorToErrorCode(Res.takeError());

    if (Code >= static_cast<unsigned>(llvm::bitc::FIRST_APPLICATION_ABBREV)) {

      // We found a record.

      BlockOrRecordID = Code;

      return Cursor::Record;

    }

    switch (static_cast<llvm::bitc::FixedAbbrevIDs>(Code)) {

    case llvm::bitc::ENTER_SUBBLOCK:

      if (Expected<unsigned> Res = Stream.ReadSubBlockID())

        BlockOrRecordID = Res.get();

      else

        return llvm::errorToErrorCode(Res.takeError());

      return Cursor::BlockBegin;

    case llvm::bitc::END_BLOCK:

      if (Stream.ReadBlockEnd())

        return SDError::InvalidDiagnostics;

      return Cursor::BlockEnd;

    case llvm::bitc::DEFINE_ABBREV:

      if (llvm::Error Err = Stream.ReadAbbrevRecord())

        return llvm::errorToErrorCode(std::move(Err));

      continue;

    case llvm::bitc::UNABBREV_RECORD:

      return SDError::UnsupportedConstruct;

    case llvm::bitc::FIRST_APPLICATION_ABBREV:

      llvm_unreachable("Unexpected abbrev id.");

    }

  }

  return SDError::InvalidDiagnostics;

}

std::error_code

SerializedDiagnosticReader::readMetaBlock(llvm::BitstreamCursor &Stream) {

  if (llvm::Error Err =

          Stream.EnterSubBlock(clang::serialized_diags::BLOCK_META)) {

    // FIXME this drops the error on the floor.

    consumeError(std::move(Err));

    return SDError::MalformedMetadataBlock;

  }

  bool VersionChecked = false;

  while (true) {

    unsigned BlockOrCode = 0;

    llvm::ErrorOr<Cursor> Res = skipUntilRecordOrBlock(Stream, BlockOrCode);

    if (!Res)

      Res.getError();

    switch (Res.get()) {

    case Cursor::Record:

      break;

    case Cursor::BlockBegin:

      if (llvm::Error Err = Stream.SkipBlock()) {

        // FIXME this drops the error on the floor.

        consumeError(std::move(Err));

        return SDError::MalformedMetadataBlock;

      }

      LLVM_FALLTHROUGH;

    case Cursor::BlockEnd:

      if (!VersionChecked)

        return SDError::MissingVersion;

      return {};

    }

    SmallVector<uint64_t, 1> Record;

    Expected<unsigned> MaybeRecordID = Stream.readRecord(BlockOrCode, Record);

    if (!MaybeRecordID)

      return errorToErrorCode(MaybeRecordID.takeError());

    unsigned RecordID = MaybeRecordID.get();

    if (RecordID == RECORD_VERSION) {

      if (Record.size() < 1)

        return SDError::MissingVersion;

      if (Record[0] > VersionNumber)

        return SDError::VersionMismatch;

      VersionChecked = true;

    }

  }

}

std::error_code

SerializedDiagnosticReader::readDiagnosticBlock(llvm::BitstreamCursor &Stream) {

  if (llvm::Error Err =

          Stream.EnterSubBlock(clang::serialized_diags::BLOCK_DIAG)) {

    // FIXME this drops the error on the floor.

    consumeError(std::move(Err));

    return SDError::MalformedDiagnosticBlock;

  }

  std::error_code EC;

  if ((EC = visitStartOfDiagnostic()))

    return EC;

  SmallVector<uint64_t, 16> Record;

  while (true) {

    unsigned BlockOrCode = 0;

    llvm::ErrorOr<Cursor> Res = skipUntilRecordOrBlock(Stream, BlockOrCode);

    if (!Res)

      Res.getError();

    switch (Res.get()) {

    case Cursor::BlockBegin:

      // The only blocks we care about are subdiagnostics.

      if (BlockOrCode == serialized_diags::BLOCK_DIAG) {

        if ((EC = readDiagnosticBlock(Stream)))

          return EC;

      } else if (llvm::Error Err = Stream.SkipBlock()) {

        // FIXME this drops the error on the floor.

        consumeError(std::move(Err));

        return SDError::MalformedSubBlock;

      }

      continue;

    case Cursor::BlockEnd:

      if ((EC = visitEndOfDiagnostic()))

        return EC;

      return {};

    case Cursor::Record:

      break;

    }

    // Read the record.

    Record.clear();

    StringRef Blob;

    Expected<unsigned> MaybeRecID =

        Stream.readRecord(BlockOrCode, Record, &Blob);

    if (!MaybeRecID)

      return errorToErrorCode(MaybeRecID.takeError());

    unsigned RecID = MaybeRecID.get();

    if (RecID < serialized_diags::RECORD_FIRST ||

        RecID > serialized_diags::RECORD_LAST)

      continue;

    switch ((RecordIDs)RecID) {

    case RECORD_CATEGORY:

      // A category has ID and name size.

      if (Record.size() != 2)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitCategoryRecord(Record[0], Blob)))

        return EC;

      continue;

    case RECORD_DIAG:

      // A diagnostic has severity, location (4), category, flag, and message

      // size.

      if (Record.size() != 8)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitDiagnosticRecord(

               Record[0], Location(Record[1], Record[2], Record[3], Record[4]),

               Record[5], Record[6], Blob)))

        return EC;

      continue;

    case RECORD_DIAG_FLAG:

      // A diagnostic flag has ID and name size.

      if (Record.size() != 2)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitDiagFlagRecord(Record[0], Blob)))

        return EC;

      continue;

    case RECORD_FILENAME:

      // A filename has ID, size, timestamp, and name size. The size and

      // timestamp are legacy fields that are always zero these days.

      if (Record.size() != 4)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitFilenameRecord(Record[0], Record[1], Record[2], Blob)))

        return EC;

      continue;

    case RECORD_FIXIT:

      // A fixit has two locations (4 each) and message size.

      if (Record.size() != 9)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitFixitRecord(

               Location(Record[0], Record[1], Record[2], Record[3]),

               Location(Record[4], Record[5], Record[6], Record[7]), Blob)))

        return EC;

      continue;

    case RECORD_SOURCE_RANGE:

      // A source range is two locations (4 each).

      if (Record.size() != 8)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitSourceRangeRecord(

               Location(Record[0], Record[1], Record[2], Record[3]),

               Location(Record[4], Record[5], Record[6], Record[7]))))

        return EC;

      continue;

    case RECORD_VERSION:

      // A version is just a number.

      if (Record.size() != 1)

        return SDError::MalformedDiagnosticRecord;

      if ((EC = visitVersionRecord(Record[0])))

        return EC;

      continue;

    }

  }

}

namespace {

class SDErrorCategoryType final : public std::error_category {

  const char *name() const noexcept override {

    return "clang.serialized_diags";

  }

  std::string message(int IE) const override {

    auto E = static_cast<SDError>(IE);

    switch (E) {

    case SDError::CouldNotLoad:

      return "Failed to open diagnostics file";

    case SDError::InvalidSignature:

      return "Invalid diagnostics signature";

    case SDError::InvalidDiagnostics:

      return "Parse error reading diagnostics";

    case SDError::MalformedTopLevelBlock:

      return "Malformed block at top-level of diagnostics";

    case SDError::MalformedSubBlock:

      return "Malformed sub-block in a diagnostic";

    case SDError::MalformedBlockInfoBlock:

      return "Malformed BlockInfo block";

    case SDError::MalformedMetadataBlock:

      return "Malformed Metadata block";

    case SDError::MalformedDiagnosticBlock:

      return "Malformed Diagnostic block";

    case SDError::MalformedDiagnosticRecord:

      return "Malformed Diagnostic record";

    case SDError::MissingVersion:

      return "No version provided in diagnostics";

    case SDError::VersionMismatch:

      return "Unsupported diagnostics version";

    case SDError::UnsupportedConstruct:

      return "Bitcode constructs that are not supported in diagnostics appear";

    case SDError::HandlerFailed:

      return "Generic error occurred while handling a record";

    }

    llvm_unreachable("Unknown error type!");

  }

};

} // namespace

static llvm::ManagedStatic<SDErrorCategoryType> ErrorCategory;

const std::error_category &clang::serialized_diags::SDErrorCategory() {

  return *ErrorCategory;

}