ObjectContainerBSDArchive.cpp

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//===-- ObjectContainerBSDArchive.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 "ObjectContainerBSDArchive.h"
 
#if defined(_WIN32) || defined(_AIX)
// Defines from ar, missing on Windows
#define SARMAG 8
#define ARFMAG "`\n"
 
typedef struct ar_hdr {
  char ar_name[16];
  char ar_date[12];
  char ar_uid[6], ar_gid[6];
  char ar_mode[8];
  char ar_size[10];
  char ar_fmag[2];
} ar_hdr;
#else
#include <ar.h>
#endif
 
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Host/FileSystem.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/ArchSpec.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Stream.h"
#include "lldb/Utility/Timer.h"
 
#include "llvm/Object/Archive.h"
#include "llvm/Support/MemoryBuffer.h"
 
using namespace lldb;
using namespace lldb_private;
 
using namespace llvm::object;
 
LLDB_PLUGIN_DEFINE(ObjectContainerBSDArchive)
 
ObjectContainerBSDArchive::Object::Object() : ar_name() {}
 
void ObjectContainerBSDArchive::Object::Clear() {
  ar_name.clear();
  modification_time = 0;
  size = 0;
  file_offset = 0;
  file_size = 0;
}
 
void ObjectContainerBSDArchive::Object::Dump() const {
  printf("name        = \"%s\"\n", ar_name.c_str());
  printf("mtime       = 0x%8.8" PRIx32 "\n", modification_time);
  printf("size        = 0x%8.8" PRIx32 " (%" PRIu32 ")\n", size, size);
  printf("file_offset = 0x%16.16" PRIx64 " (%" PRIu64 ")\n", file_offset,
         file_offset);
  printf("file_size   = 0x%16.16" PRIx64 " (%" PRIu64 ")\n\n", file_size,
         file_size);
}
 
ObjectContainerBSDArchive::Archive::Archive(const ArchSpec &arch,
                                            const llvm::sys::TimePoint<> &time,
                                            lldb::offset_t file_offset,
                                            lldb::DataExtractorSP extractor_sp,
                                            ArchiveType archive_type)
    : m_arch(arch), m_modification_time(time), m_file_offset(file_offset),
      m_objects(), m_extractor_sp(extractor_sp), m_archive_type(archive_type) {}
 
Log *l = GetLog(LLDBLog::Object);
ObjectContainerBSDArchive::Archive::~Archive() = default;
 
size_t ObjectContainerBSDArchive::Archive::ParseObjects() {
  std::unique_ptr<llvm::MemoryBuffer> mem_buffer =
      llvm::MemoryBuffer::getMemBuffer(
          llvm::StringRef((const char *)m_extractor_sp->GetDataStart(),
                          m_extractor_sp->GetByteSize()),
          llvm::StringRef(),
          /*RequiresNullTerminator=*/false);
 
  auto exp_ar = llvm::object::Archive::create(mem_buffer->getMemBufferRef());
  if (!exp_ar) {
    LLDB_LOG_ERROR(l, exp_ar.takeError(), "failed to create archive: {0}");
    return 0;
  }
  auto llvm_archive = std::move(exp_ar.get());
 
  llvm::Error iter_err = llvm::Error::success();
  Object obj;
  for (const auto &child : llvm_archive->children(iter_err)) {
    obj.Clear();
    auto exp_name = child.getName();
    if (exp_name) {
      obj.ar_name = exp_name.get().str();
    } else {
      LLDB_LOG_ERROR(l, exp_name.takeError(),
                     "failed to get archive object name: {0}");
      continue;
    }
 
    auto exp_mtime = child.getLastModified();
    if (exp_mtime) {
      obj.modification_time =
          std::chrono::duration_cast<std::chrono::seconds>(
              std::chrono::time_point_cast<std::chrono::seconds>(
                  exp_mtime.get())
                  .time_since_epoch())
              .count();
    } else {
      LLDB_LOG_ERROR(l, exp_mtime.takeError(),
                     "failed to get archive object time: {0}");
      continue;
    }
 
    auto exp_size = child.getRawSize();
    if (exp_size) {
      obj.size = exp_size.get();
    } else {
      LLDB_LOG_ERROR(l, exp_size.takeError(),
                     "failed to get archive object size: {0}");
      continue;
    }
 
    obj.file_offset = child.getDataOffset();
 
    auto exp_file_size = child.getSize();
    if (exp_file_size) {
      obj.file_size = exp_file_size.get();
    } else {
      LLDB_LOG_ERROR(l, exp_file_size.takeError(),
                     "failed to get archive object file size: {0}");
      continue;
    }
    auto &indices = m_object_name_to_index_map[obj.ar_name];
    indices.push_back(m_objects.size());
    m_objects.push_back(obj);
  }
  if (iter_err) {
    LLDB_LOG_ERROR(l, std::move(iter_err),
                   "failed to iterate over archive objects: {0}");
  }
  return m_objects.size();
}
 
ObjectContainerBSDArchive::Object *
ObjectContainerBSDArchive::Archive::FindObject(
    llvm::StringRef object_name,
    const llvm::sys::TimePoint<> &object_mod_time) {
  auto it = m_object_name_to_index_map.find(object_name);
  if (it == m_object_name_to_index_map.end())
    return nullptr;
  if (object_mod_time == llvm::sys::TimePoint<>())
    return &m_objects[it->second.front()];
 
  const uint64_t object_modification_date = llvm::sys::toTimeT(object_mod_time);
  for (uint32_t idx : it->second) {
    if (m_objects[idx].modification_time == object_modification_date)
      return &m_objects[idx];
  }
  return nullptr;
}
 
ObjectContainerBSDArchive::ArchiveSP
ObjectContainerBSDArchive::Archive::FindCachedArchive(
    const FileSpec &file, const ArchSpec &arch,
    const llvm::sys::TimePoint<> &time, lldb::offset_t file_offset) {
  std::lock_guard<std::recursive_mutex> guard(Archive::GetArchiveCacheMutex());
  ArchiveSP archive_sp;
  Archive::Map &archive_map = Archive::GetArchiveCache();
  Archive::Map::iterator pos = archive_map.find(file);
  // Don't cache a value for "archive_map.end()" below since we might delete an
  // archive entry...
  while (pos != archive_map.end() && pos->first == file) {
    bool match = true;
    if (arch.IsValid() &&
        !pos->second->GetArchitecture().IsCompatibleMatch(arch))
      match = false;
    else if (file_offset != LLDB_INVALID_OFFSET &&
             pos->second->GetFileOffset() != file_offset)
      match = false;
    if (match) {
      if (pos->second->GetModificationTime() == time) {
        return pos->second;
      } else {
        // We have a file at the same path with the same architecture whose
        // modification time doesn't match. It doesn't make sense for us to
        // continue to use this BSD archive since we cache only the object info
        // which consists of file time info and also the file offset and file
        // size of any contained objects. Since this information is now out of
        // date, we won't get the correct information if we go and extract the
        // file data, so we should remove the old and outdated entry.
        archive_map.erase(pos);
        pos = archive_map.find(file);
        continue; // Continue to next iteration so we don't increment pos
                  // below...
      }
    }
    ++pos;
  }
  return archive_sp;
}
 
ObjectContainerBSDArchive::ArchiveSP
ObjectContainerBSDArchive::Archive::ParseAndCacheArchiveForFile(
    const FileSpec &file, const ArchSpec &arch,
    const llvm::sys::TimePoint<> &time, lldb::offset_t file_offset,
    DataExtractorSP extractor_sp, ArchiveType archive_type) {
  ArchiveSP archive_sp = std::make_shared<Archive>(arch, time, file_offset,
                                                   extractor_sp, archive_type);
  if (archive_sp) {
    const size_t num_objects = archive_sp->ParseObjects();
    if (num_objects > 0) {
      std::lock_guard<std::recursive_mutex> guard(
          Archive::GetArchiveCacheMutex());
      Archive::GetArchiveCache().insert(std::make_pair(file, archive_sp));
    } else {
      archive_sp.reset();
    }
  }
  return archive_sp;
}
 
ObjectContainerBSDArchive::Archive::Map &
ObjectContainerBSDArchive::Archive::GetArchiveCache() {
  static Archive::Map g_archive_map;
  return g_archive_map;
}
 
std::recursive_mutex &
ObjectContainerBSDArchive::Archive::GetArchiveCacheMutex() {
  static std::recursive_mutex g_archive_map_mutex;
  return g_archive_map_mutex;
}
 
void ObjectContainerBSDArchive::Initialize() {
  PluginManager::RegisterPlugin(GetPluginNameStatic(),
                                GetPluginDescriptionStatic(), CreateInstance,
                                GetModuleSpecifications);
}
 
void ObjectContainerBSDArchive::Terminate() {
  PluginManager::UnregisterPlugin(CreateInstance);
}
 
ObjectContainer *ObjectContainerBSDArchive::CreateInstance(
    const lldb::ModuleSP &module_sp, DataBufferSP &data_sp,
    lldb::offset_t data_offset, const FileSpec *file,
    lldb::offset_t file_offset, lldb::offset_t length) {
  ConstString object_name(module_sp->GetObjectName());
  if (!object_name)
    return nullptr;
 
  if (data_sp) {
    // We have data, which means this is the first 512 bytes of the file Check
    // to see if the magic bytes match and if they do, read the entire table of
    // contents for the archive and cache it
    DataExtractor data;
    data.SetData(data_sp, data_offset, length);
    ArchiveType archive_type = ObjectContainerBSDArchive::MagicBytesMatch(data);
    if (file && data_sp && archive_type != ArchiveType::Invalid) {
      LLDB_SCOPED_TIMERF(
          "ObjectContainerBSDArchive::CreateInstance (module = %s, file = "
          "%p, file_offset = 0x%8.8" PRIx64 ", file_size = 0x%8.8" PRIx64 ")",
          module_sp->GetFileSpec().GetPath().c_str(),
          static_cast<const void *>(file), static_cast<uint64_t>(file_offset),
          static_cast<uint64_t>(length));
 
      // Map the entire .a file to be sure that we don't lose any data if the
      // file gets updated by a new build while this .a file is being used for
      // debugging
      DataBufferSP archive_data_sp =
          FileSystem::Instance().CreateDataBuffer(*file, length, file_offset);
      if (!archive_data_sp)
        return nullptr;
 
      lldb::offset_t archive_data_offset = 0;
 
      ArchiveSP archive_sp(Archive::FindCachedArchive(
          *file, module_sp->GetArchitecture(), module_sp->GetModificationTime(),
          file_offset));
      std::unique_ptr<ObjectContainerBSDArchive> container_up(
          new ObjectContainerBSDArchive(module_sp, archive_data_sp,
                                        archive_data_offset, file, file_offset,
                                        length, archive_type));
 
      if (container_up) {
        if (archive_sp) {
          // We already have this archive in our cache, use it
          container_up->SetArchive(archive_sp);
          return container_up.release();
        } else if (container_up->ParseHeader())
          return container_up.release();
      }
    }
  } else {
    // No data, just check for a cached archive
    ArchiveSP archive_sp(Archive::FindCachedArchive(
        *file, module_sp->GetArchitecture(), module_sp->GetModificationTime(),
        file_offset));
    if (archive_sp) {
      std::unique_ptr<ObjectContainerBSDArchive> container_up(
          new ObjectContainerBSDArchive(module_sp, data_sp, data_offset, file,
                                        file_offset, length,
                                        archive_sp->GetArchiveType()));
 
      if (container_up) {
        // We already have this archive in our cache, use it
        container_up->SetArchive(archive_sp);
        return container_up.release();
      }
    }
  }
  return nullptr;
}
 
ArchiveType
ObjectContainerBSDArchive::MagicBytesMatch(const DataExtractor &data) {
  uint32_t offset = 0;
  const char *armag =
      (const char *)data.PeekData(offset, sizeof(ar_hdr) + SARMAG);
  if (armag == nullptr)
    return ArchiveType::Invalid;
  ArchiveType result = ArchiveType::Invalid;
  if (strncmp(armag, ArchiveMagic, SARMAG) == 0)
    result = ArchiveType::Archive;
  else if (strncmp(armag, ThinArchiveMagic, SARMAG) == 0)
    result = ArchiveType::ThinArchive;
  else
    return ArchiveType::Invalid;
 
  armag += offsetof(struct ar_hdr, ar_fmag) + SARMAG;
  if (strncmp(armag, ARFMAG, 2) == 0)
    return result;
  return ArchiveType::Invalid;
}
 
ObjectContainerBSDArchive::ObjectContainerBSDArchive(
    const lldb::ModuleSP &module_sp, DataBufferSP &data_sp,
    lldb::offset_t data_offset, const FileSpec *file,
    lldb::offset_t file_offset, lldb::offset_t size, ArchiveType archive_type)
    : ObjectContainer(module_sp, file, file_offset, size, data_sp, data_offset),
      m_archive_sp() {
  m_archive_type = archive_type;
}
 
void ObjectContainerBSDArchive::SetArchive(ArchiveSP &archive_sp) {
  m_archive_sp = archive_sp;
}
 
ObjectContainerBSDArchive::~ObjectContainerBSDArchive() = default;
 
bool ObjectContainerBSDArchive::ParseHeader() {
  if (m_archive_sp.get() == nullptr) {
    if (m_extractor_sp->GetByteSize() > 0) {
      ModuleSP module_sp(GetModule());
      if (module_sp) {
        m_archive_sp = Archive::ParseAndCacheArchiveForFile(
            m_file, module_sp->GetArchitecture(),
            module_sp->GetModificationTime(), m_offset, m_extractor_sp,
            m_archive_type);
      }
      // Clear the m_extractor_sp that contains the entire archive data and let
      // our m_archive_sp hold onto the data.  Need to have an empty
      // DataExtractor for code that assumes it is non-null.
      m_extractor_sp = std::make_shared<DataExtractor>();
    }
  }
  return m_archive_sp.get() != nullptr;
}
 
FileSpec GetChildFileSpecificationsFromThin(llvm::StringRef childPath,
                                            const FileSpec &parentFileSpec) {
  llvm::SmallString<128> FullPath;
  if (llvm::sys::path::is_absolute(childPath)) {
    FullPath = childPath;
  } else {
    FullPath = parentFileSpec.GetDirectory();
    llvm::sys::path::append(FullPath, childPath);
  }
  FileSpec child = FileSpec(FullPath.str(), llvm::sys::path::Style::posix);
  return child;
}
 
ObjectFileSP ObjectContainerBSDArchive::GetObjectFile(const FileSpec *file) {
  ModuleSP module_sp(GetModule());
  if (module_sp) {
    if (module_sp->GetObjectName() && m_archive_sp) {
      Object *object = m_archive_sp->FindObject(
          module_sp->GetObjectName(), module_sp->GetObjectModificationTime());
      if (object) {
        if (m_archive_type == ArchiveType::ThinArchive) {
          // Set file to child object file
          FileSpec child =
              GetChildFileSpecificationsFromThin(object->ar_name, m_file);
          lldb::offset_t file_offset = 0;
          lldb::offset_t file_size = object->size;
          DataBufferSP child_data_sp = FileSystem::Instance().CreateDataBuffer(
              child, file_size, file_offset);
          if (!child_data_sp ||
              child_data_sp->GetByteSize() != object->file_size)
            return ObjectFileSP();
          lldb::offset_t data_offset = 0;
          DataExtractorSP extractor_sp =
              std::make_shared<DataExtractor>(child_data_sp);
          return lldb_private::ObjectFile::FindPlugin(
              module_sp, &child, m_offset + object->file_offset,
              object->file_size, extractor_sp, data_offset);
        }
        lldb::offset_t data_offset = object->file_offset;
        // Create a new DataExtractor object, its DataBuffer will be shared.
        DataExtractorSP extractor_sp =
            std::make_shared<DataExtractor>(m_archive_sp->GetData());
        return lldb_private::ObjectFile::FindPlugin(
            module_sp, file, m_offset + object->file_offset, object->file_size,
            extractor_sp, data_offset);
      }
    }
  }
  return ObjectFileSP();
}
 
ModuleSpecList ObjectContainerBSDArchive::GetModuleSpecifications(
    const FileSpec &file, lldb::DataExtractorSP &extractor_sp,
    lldb::offset_t file_offset, lldb::offset_t file_size) {
 
  if (!file || !extractor_sp)
    return {};
 
  // We have data, which means this is the first 512 bytes of the file Check to
  // see if the magic bytes match and if they do, read the entire table of
  // contents for the archive and cache it
  ArchiveType archive_type = MagicBytesMatch(*extractor_sp);
  if (archive_type == ArchiveType::Invalid)
    return {};
 
  llvm::sys::TimePoint<> file_mod_time =
      FileSystem::Instance().GetModificationTime(file);
  ArchiveSP archive_sp(
      Archive::FindCachedArchive(file, ArchSpec(), file_mod_time, file_offset));
  bool set_archive_arch = false;
  if (!archive_sp) {
    set_archive_arch = true;
    DataBufferSP data_sp =
        FileSystem::Instance().CreateDataBuffer(file, file_size, file_offset);
    if (data_sp) {
      extractor_sp->SetData(data_sp);
      archive_sp = Archive::ParseAndCacheArchiveForFile(
          file, ArchSpec(), file_mod_time, file_offset, extractor_sp,
          archive_type);
    }
  }
 
  ModuleSpecList specs;
  if (archive_sp) {
    const size_t num_objects = archive_sp->GetNumObjects();
    for (size_t idx = 0; idx < num_objects; ++idx) {
      const Object *object = archive_sp->GetObjectAtIndex(idx);
      if (object) {
        if (archive_sp->GetArchiveType() == ArchiveType::ThinArchive) {
          if (object->ar_name.empty())
            continue;
          FileSpec child =
              GetChildFileSpecificationsFromThin(object->ar_name, file);
          ModuleSpecList object_specs =
              lldb_private::ObjectFile::GetModuleSpecifications(
                  child, 0, object->file_size);
          if (object_specs.GetSize() > 0) {
            ModuleSpec &spec = object_specs.GetModuleSpecRefAtIndex(
                object_specs.GetSize() - 1);
            llvm::sys::TimePoint<> object_mod_time(
                std::chrono::seconds(object->modification_time));
            spec.GetObjectName() = ConstString(object->ar_name);
            spec.SetObjectOffset(0);
            spec.SetObjectSize(object->file_size);
            spec.GetObjectModificationTime() = object_mod_time;
            specs.Append(spec);
          }
          continue;
        }
        const lldb::offset_t object_file_offset =
            file_offset + object->file_offset;
        if (object->file_offset < file_size && file_size > object_file_offset) {
          ModuleSpecList object_specs =
              lldb_private::ObjectFile::GetModuleSpecifications(
                  file, object_file_offset, file_size - object_file_offset);
          if (object_specs.GetSize() > 0) {
            ModuleSpec &spec = object_specs.GetModuleSpecRefAtIndex(
                object_specs.GetSize() - 1);
            llvm::sys::TimePoint<> object_mod_time(
                std::chrono::seconds(object->modification_time));
            spec.GetObjectName() = ConstString(object->ar_name);
            spec.SetObjectOffset(object_file_offset);
            spec.SetObjectSize(object->file_size);
            spec.GetObjectModificationTime() = object_mod_time;
            specs.Append(spec);
          }
        }
      }
    }
  }
  const size_t end_count = specs.GetSize();
  if (set_archive_arch && specs.GetSize() > 0) {
    // The archive was created but we didn't have an architecture so we need to
    // set it
    for (size_t i = 0; i < end_count; ++i) {
      ModuleSpec module_spec;
      if (specs.GetModuleSpecAtIndex(i, module_spec)) {
        if (module_spec.GetArchitecture().IsValid()) {
          archive_sp->SetArchitecture(module_spec.GetArchitecture());
          break;
        }
      }
    }
  }
  return specs;
}