llvm-project/lldb/source/Plugins/ObjectFile/JSON/ObjectFileJSON.cpp

//===-- ObjectFileJSON.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 "Plugins/ObjectFile/JSON/ObjectFileJSON.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Section.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "llvm/ADT/DenseSet.h"
#include <optional>

using namespace llvm;
using namespace lldb;
using namespace lldb_private;

LLDB_PLUGIN_DEFINE(ObjectFileJSON)

char ObjectFileJSON::ID;

void ObjectFileJSON::Initialize() {
  PluginManager::RegisterPlugin(GetPluginNameStatic(),
                                GetPluginDescriptionStatic(), CreateInstance,
                                CreateMemoryInstance, GetModuleSpecifications);
}

void ObjectFileJSON::Terminate() {
  PluginManager::UnregisterPlugin(CreateInstance);
}

ObjectFile *
ObjectFileJSON::CreateInstance(const ModuleSP &module_sp, DataBufferSP data_sp,
                               offset_t data_offset, const FileSpec *file,
                               offset_t file_offset, offset_t length) {
  if (!data_sp) {
    data_sp = MapFileData(*file, length, file_offset);
    if (!data_sp)
      return nullptr;
    data_offset = 0;
  }

  if (!MagicBytesMatch(data_sp, 0, data_sp->GetByteSize()))
    return nullptr;

  if (data_sp->GetByteSize() < length) {
    data_sp = MapFileData(*file, length, file_offset);
    if (!data_sp)
      return nullptr;
    data_offset = 0;
  }

  auto text =
      llvm::StringRef(reinterpret_cast<const char *>(data_sp->GetBytes()));

  Expected<json::Value> json = json::parse(text);
  if (!json) {
    llvm::consumeError(json.takeError());
    return nullptr;
  }

  json::Path::Root root;
  Header header;
  if (!fromJSON(*json, header, root))
    return nullptr;

  ArchSpec arch(header.triple);
  UUID uuid;
  uuid.SetFromStringRef(header.uuid);

  Body body;
  fromJSON(*json, body, root);

  return new ObjectFileJSON(module_sp, data_sp, data_offset, file, file_offset,
                            length, std::move(arch), std::move(uuid),
                            std::move(body.symbols));
}

ObjectFile *ObjectFileJSON::CreateMemoryInstance(const ModuleSP &module_sp,
                                                 WritableDataBufferSP data_sp,
                                                 const ProcessSP &process_sp,
                                                 addr_t header_addr) {
  return nullptr;
}

size_t ObjectFileJSON::GetModuleSpecifications(
    const FileSpec &file, DataBufferSP &data_sp, offset_t data_offset,
    offset_t file_offset, offset_t length, ModuleSpecList &specs) {

  if (!MagicBytesMatch(data_sp, data_offset, data_sp->GetByteSize()))
    return 0;

  auto text =
      llvm::StringRef(reinterpret_cast<const char *>(data_sp->GetBytes()));

  Expected<json::Value> json = json::parse(text);
  if (!json) {
    llvm::consumeError(json.takeError());
    return 0;
  }

  json::Path::Root root;
  Header header;
  if (!fromJSON(*json, header, root))
    return 0;

  ArchSpec arch(header.triple);
  UUID uuid;
  uuid.SetFromStringRef(header.uuid);

  ModuleSpec spec(file, std::move(arch));
  spec.GetUUID() = std::move(uuid);
  specs.Append(spec);
  return 1;
}

ObjectFileJSON::ObjectFileJSON(const ModuleSP &module_sp, DataBufferSP &data_sp,
                               offset_t data_offset, const FileSpec *file,
                               offset_t offset, offset_t length, ArchSpec arch,
                               UUID uuid, std::vector<JSONSymbol> symbols)
    : ObjectFile(module_sp, file, offset, length, data_sp, data_offset),
      m_arch(std::move(arch)), m_uuid(std::move(uuid)),
      m_symbols(std::move(symbols)) {}

bool ObjectFileJSON::ParseHeader() {
  // We already parsed the header during initialization.
  return true;
}

void ObjectFileJSON::ParseSymtab(Symtab &symtab) {
  Log *log = GetLog(LLDBLog::Symbols);
  SectionList *section_list = GetModule()->GetSectionList();
  for (JSONSymbol json_symbol : m_symbols) {
    llvm::Expected<Symbol> symbol = Symbol::FromJSON(json_symbol, section_list);
    if (!symbol) {
      LLDB_LOG_ERROR(log, symbol.takeError(), "invalid symbol");
      continue;
    }
    symtab.AddSymbol(*symbol);
  }
  symtab.Finalize();
}

void ObjectFileJSON::CreateSections(SectionList &unified_section_list) {}

bool ObjectFileJSON::MagicBytesMatch(DataBufferSP data_sp,
                                     lldb::addr_t data_offset,
                                     lldb::addr_t data_length) {
  DataExtractor data;
  data.SetData(data_sp, data_offset, data_length);
  lldb::offset_t offset = 0;
  uint32_t magic = data.GetU8(&offset);
  return magic == '{';
}

namespace lldb_private {

bool fromJSON(const json::Value &value, ObjectFileJSON::Header &header,
              json::Path path) {
  json::ObjectMapper o(value, path);
  return o && o.map("triple", header.triple) && o.map("uuid", header.uuid);
}

bool fromJSON(const json::Value &value, ObjectFileJSON::Body &body,
              json::Path path) {
  json::ObjectMapper o(value, path);
  return o && o.map("symbols", body.symbols);
}

} // namespace lldb_private