Process/mach-core/ProcessMachCore.cpp

//===-- ProcessMachCore.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 <errno.h>
#include <stdlib.h>

#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Threading.h"

#include "lldb/Core/Debugger.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Section.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/LocateSymbolFile.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/MemoryRegionInfo.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/DataBuffer.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/State.h"

#include "ProcessMachCore.h"
#include "Plugins/Process/Utility/StopInfoMachException.h"
#include "ThreadMachCore.h"

// Needed for the plug-in names for the dynamic loaders.
#include "lldb/Host/SafeMachO.h"

#include "Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h"
#include "Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.h"
#include "Plugins/ObjectFile/Mach-O/ObjectFileMachO.h"

#include <memory>
#include <mutex>

using namespace lldb;
using namespace lldb_private;

LLDB_PLUGIN_DEFINE(ProcessMachCore)

ConstString ProcessMachCore::GetPluginNameStatic() {
  static ConstString g_name("mach-o-core");
  return g_name;
}

const char *ProcessMachCore::GetPluginDescriptionStatic() {
  return "Mach-O core file debugging plug-in.";
}

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

lldb::ProcessSP ProcessMachCore::CreateInstance(lldb::TargetSP target_sp,
                                                ListenerSP listener_sp,
                                                const FileSpec *crash_file) {
  lldb::ProcessSP process_sp;
  if (crash_file) {
    const size_t header_size = sizeof(llvm::MachO::mach_header);
    auto data_sp = FileSystem::Instance().CreateDataBuffer(
        crash_file->GetPath(), header_size, 0);
    if (data_sp && data_sp->GetByteSize() == header_size) {
      DataExtractor data(data_sp, lldb::eByteOrderLittle, 4);

      lldb::offset_t data_offset = 0;
      llvm::MachO::mach_header mach_header;
      if (ObjectFileMachO::ParseHeader(data, &data_offset, mach_header)) {
        if (mach_header.filetype == llvm::MachO::MH_CORE)
          process_sp = std::make_shared<ProcessMachCore>(target_sp, listener_sp,
                                                         *crash_file);
      }
    }
  }
  return process_sp;
}

bool ProcessMachCore::CanDebug(lldb::TargetSP target_sp,
                               bool plugin_specified_by_name) {
  if (plugin_specified_by_name)
    return true;

  // For now we are just making sure the file exists for a given module
  if (!m_core_module_sp && FileSystem::Instance().Exists(m_core_file)) {
    // Don't add the Target's architecture to the ModuleSpec - we may be
    // working with a core file that doesn't have the correct cpusubtype in the
    // header but we should still try to use it -
    // ModuleSpecList::FindMatchingModuleSpec enforces a strict arch mach.
    ModuleSpec core_module_spec(m_core_file);
    Status error(ModuleList::GetSharedModule(core_module_spec, m_core_module_sp,
                                             nullptr, nullptr, nullptr));

    if (m_core_module_sp) {
      ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();
      if (core_objfile && core_objfile->GetType() == ObjectFile::eTypeCoreFile)
        return true;
    }
  }
  return false;
}

// ProcessMachCore constructor
ProcessMachCore::ProcessMachCore(lldb::TargetSP target_sp,
                                 ListenerSP listener_sp,
                                 const FileSpec &core_file)
    : Process(target_sp, listener_sp), m_core_aranges(), m_core_range_infos(),
      m_core_module_sp(), m_core_file(core_file),
      m_dyld_addr(LLDB_INVALID_ADDRESS),
      m_mach_kernel_addr(LLDB_INVALID_ADDRESS), m_dyld_plugin_name() {}

// Destructor
ProcessMachCore::~ProcessMachCore() {
  Clear();
  // We need to call finalize on the process before destroying ourselves to
  // make sure all of the broadcaster cleanup goes as planned. If we destruct
  // this class, then Process::~Process() might have problems trying to fully
  // destroy the broadcaster.
  Finalize();
}

// PluginInterface
ConstString ProcessMachCore::GetPluginName() { return GetPluginNameStatic(); }

uint32_t ProcessMachCore::GetPluginVersion() { return 1; }

bool ProcessMachCore::GetDynamicLoaderAddress(lldb::addr_t addr) {
  Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER |
                                                  LIBLLDB_LOG_PROCESS));
  llvm::MachO::mach_header header;
  Status error;
  if (DoReadMemory(addr, &header, sizeof(header), error) != sizeof(header))
    return false;
  if (header.magic == llvm::MachO::MH_CIGAM ||
      header.magic == llvm::MachO::MH_CIGAM_64) {
    header.magic = llvm::ByteSwap_32(header.magic);
    header.cputype = llvm::ByteSwap_32(header.cputype);
    header.cpusubtype = llvm::ByteSwap_32(header.cpusubtype);
    header.filetype = llvm::ByteSwap_32(header.filetype);
    header.ncmds = llvm::ByteSwap_32(header.ncmds);
    header.sizeofcmds = llvm::ByteSwap_32(header.sizeofcmds);
    header.flags = llvm::ByteSwap_32(header.flags);
  }

  // TODO: swap header if needed...
  // printf("0x%16.16" PRIx64 ": magic = 0x%8.8x, file_type= %u\n", vaddr,
  // header.magic, header.filetype);
  if (header.magic == llvm::MachO::MH_MAGIC ||
      header.magic == llvm::MachO::MH_MAGIC_64) {
    // Check MH_EXECUTABLE to see if we can find the mach image that contains
    // the shared library list. The dynamic loader (dyld) is what contains the
    // list for user applications, and the mach kernel contains a global that
    // has the list of kexts to load
    switch (header.filetype) {
    case llvm::MachO::MH_DYLINKER:
      // printf("0x%16.16" PRIx64 ": file_type = MH_DYLINKER\n", vaddr);
      // Address of dyld "struct mach_header" in the core file
      LLDB_LOGF(log,
                "ProcessMachCore::GetDynamicLoaderAddress found a user "
                "process dyld binary image at 0x%" PRIx64,
                addr);
      m_dyld_addr = addr;
      return true;

    case llvm::MachO::MH_EXECUTE:
      // printf("0x%16.16" PRIx64 ": file_type = MH_EXECUTE\n", vaddr);
      // Check MH_EXECUTABLE file types to see if the dynamic link object flag
      // is NOT set. If it isn't, then we have a mach_kernel.
      if ((header.flags & llvm::MachO::MH_DYLDLINK) == 0) {
        LLDB_LOGF(log,
                  "ProcessMachCore::GetDynamicLoaderAddress found a mach "
                  "kernel binary image at 0x%" PRIx64,
                  addr);
        // Address of the mach kernel "struct mach_header" in the core file.
        m_mach_kernel_addr = addr;
        return true;
      }
      break;
    }
  }
  return false;
}

// Process Control
Status ProcessMachCore::DoLoadCore() {
  Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER |
                                                  LIBLLDB_LOG_PROCESS));
  Status error;
  if (!m_core_module_sp) {
    error.SetErrorString("invalid core module");
    return error;
  }

  ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();
  if (core_objfile == nullptr) {
    error.SetErrorString("invalid core object file");
    return error;
  }

  if (core_objfile->GetNumThreadContexts() == 0) {
    error.SetErrorString("core file doesn't contain any LC_THREAD load "
                         "commands, or the LC_THREAD architecture is not "
                         "supported in this lldb");
    return error;
  }

  SectionList *section_list = core_objfile->GetSectionList();
  if (section_list == nullptr) {
    error.SetErrorString("core file has no sections");
    return error;
  }

  const uint32_t num_sections = section_list->GetNumSections(0);
  if (num_sections == 0) {
    error.SetErrorString("core file has no sections");
    return error;
  }

  SetCanJIT(false);

  llvm::MachO::mach_header header;
  DataExtractor data(&header, sizeof(header),
                     m_core_module_sp->GetArchitecture().GetByteOrder(),
                     m_core_module_sp->GetArchitecture().GetAddressByteSize());

  bool ranges_are_sorted = true;
  addr_t vm_addr = 0;
  for (uint32_t i = 0; i < num_sections; ++i) {
    Section *section = section_list->GetSectionAtIndex(i).get();
    if (section) {
      lldb::addr_t section_vm_addr = section->GetFileAddress();
      FileRange file_range(section->GetFileOffset(), section->GetFileSize());
      VMRangeToFileOffset::Entry range_entry(
          section_vm_addr, section->GetByteSize(), file_range);

      if (vm_addr > section_vm_addr)
        ranges_are_sorted = false;
      vm_addr = section->GetFileAddress();
      VMRangeToFileOffset::Entry *last_entry = m_core_aranges.Back();
      //            printf ("LC_SEGMENT[%u] arange=[0x%16.16" PRIx64 " -
      //            0x%16.16" PRIx64 "), frange=[0x%8.8x - 0x%8.8x)\n",
      //                    i,
      //                    range_entry.GetRangeBase(),
      //                    range_entry.GetRangeEnd(),
      //                    range_entry.data.GetRangeBase(),
      //                    range_entry.data.GetRangeEnd());

      if (last_entry &&
          last_entry->GetRangeEnd() == range_entry.GetRangeBase() &&
          last_entry->data.GetRangeEnd() == range_entry.data.GetRangeBase()) {
        last_entry->SetRangeEnd(range_entry.GetRangeEnd());
        last_entry->data.SetRangeEnd(range_entry.data.GetRangeEnd());
        // puts("combine");
      } else {
        m_core_aranges.Append(range_entry);
      }
      // Some core files don't fill in the permissions correctly. If that is
      // the case assume read + execute so clients don't think the memory is
      // not readable, or executable. The memory isn't writable since this
      // plug-in doesn't implement DoWriteMemory.
      uint32_t permissions = section->GetPermissions();
      if (permissions == 0)
        permissions = lldb::ePermissionsReadable | lldb::ePermissionsExecutable;
      m_core_range_infos.Append(VMRangeToPermissions::Entry(
          section_vm_addr, section->GetByteSize(), permissions));
    }
  }
  if (!ranges_are_sorted) {
    m_core_aranges.Sort();
    m_core_range_infos.Sort();
  }


  bool found_main_binary_definitively = false;

  addr_t objfile_binary_addr;
  UUID objfile_binary_uuid;
  if (core_objfile->GetCorefileMainBinaryInfo (objfile_binary_addr, objfile_binary_uuid))
  {
    if (objfile_binary_addr != LLDB_INVALID_ADDRESS)
    {
        m_mach_kernel_addr = objfile_binary_addr;
        found_main_binary_definitively = true;
        LLDB_LOGF(log,
                  "ProcessMachCore::DoLoadCore: using kernel address 0x%" PRIx64
                  " from LC_NOTE 'main bin spec' load command.",
                  m_mach_kernel_addr);
    }
  }

  // This checks for the presence of an LC_IDENT string in a core file;
  // LC_IDENT is very obsolete and should not be used in new code, but if the
  // load command is present, let's use the contents.
  std::string corefile_identifier = core_objfile->GetIdentifierString();
  if (!found_main_binary_definitively &&
      corefile_identifier.find("Darwin Kernel") != std::string::npos) {
    UUID uuid;
    addr_t addr = LLDB_INVALID_ADDRESS;
    if (corefile_identifier.find("UUID=") != std::string::npos) {
      size_t p = corefile_identifier.find("UUID=") + strlen("UUID=");
      std::string uuid_str = corefile_identifier.substr(p, 36);
      uuid.SetFromStringRef(uuid_str);
    }
    if (corefile_identifier.find("stext=") != std::string::npos) {
      size_t p = corefile_identifier.find("stext=") + strlen("stext=");
      if (corefile_identifier[p] == '0' && corefile_identifier[p + 1] == 'x') {
        errno = 0;
        addr = ::strtoul(corefile_identifier.c_str() + p, nullptr, 16);
        if (errno != 0 || addr == 0)
          addr = LLDB_INVALID_ADDRESS;
      }
    }
    if (uuid.IsValid() && addr != LLDB_INVALID_ADDRESS) {
      m_mach_kernel_addr = addr;
      found_main_binary_definitively = true;
      LLDB_LOGF(
          log,
          "ProcessMachCore::DoLoadCore: Using the kernel address 0x%" PRIx64
          " from LC_IDENT/LC_NOTE 'kern ver str' string: '%s'",
          addr, corefile_identifier.c_str());
    }
  }
  if (found_main_binary_definitively == false
      && corefile_identifier.find("EFI ") != std::string::npos) {
      UUID uuid;
      if (corefile_identifier.find("UUID=") != std::string::npos) {
          size_t p = corefile_identifier.find("UUID=") + strlen("UUID=");
          std::string uuid_str = corefile_identifier.substr(p, 36);
          uuid.SetFromStringRef(uuid_str);
      }
      if (uuid.IsValid()) {
        LLDB_LOGF(log,
                  "ProcessMachCore::DoLoadCore: Using the EFI "
                  "from LC_IDENT/LC_NOTE 'kern ver str' string: '%s'",
                  corefile_identifier.c_str());

        // We're only given a UUID here, not a load address.
        // But there are python scripts in the EFI binary's dSYM which
        // know how to relocate the binary to the correct load address.
        // lldb only needs to locate & load the binary + dSYM.
        ModuleSpec module_spec;
        module_spec.GetUUID() = uuid;
        module_spec.GetArchitecture() = GetTarget().GetArchitecture();

        // Lookup UUID locally, before attempting dsymForUUID like action
        FileSpecList search_paths = Target::GetDefaultDebugFileSearchPaths();
        module_spec.GetSymbolFileSpec() =
            Symbols::LocateExecutableSymbolFile(module_spec, search_paths);
        if (module_spec.GetSymbolFileSpec()) {
          ModuleSpec executable_module_spec =
              Symbols::LocateExecutableObjectFile(module_spec);
          if (FileSystem::Instance().Exists(
                  executable_module_spec.GetFileSpec())) {
            module_spec.GetFileSpec() = executable_module_spec.GetFileSpec();
          }
        }

        // Force a a dsymForUUID lookup, if that tool is available.
        if (!module_spec.GetSymbolFileSpec())
          Symbols::DownloadObjectAndSymbolFile(module_spec, true);

        if (FileSystem::Instance().Exists(module_spec.GetFileSpec())) {
          ModuleSP module_sp(new Module(module_spec));
          if (module_sp.get() && module_sp->GetObjectFile()) {
            // Get the current target executable
            ModuleSP exe_module_sp(GetTarget().GetExecutableModule());

            // Make sure you don't already have the right module loaded
            // and they will be uniqued
            if (exe_module_sp.get() != module_sp.get())
              GetTarget().SetExecutableModule(module_sp, eLoadDependentsNo);
          }
        }
      }
  }

  if (!found_main_binary_definitively &&
      (m_dyld_addr == LLDB_INVALID_ADDRESS ||
       m_mach_kernel_addr == LLDB_INVALID_ADDRESS)) {
    // We need to locate the main executable in the memory ranges we have in
    // the core file.  We need to search for both a user-process dyld binary
    // and a kernel binary in memory; we must look at all the pages in the
    // binary so we don't miss one or the other.  Step through all memory
    // segments searching for a kernel binary and for a user process dyld --
    // we'll decide which to prefer later if both are present.

    const size_t num_core_aranges = m_core_aranges.GetSize();
    for (size_t i = 0; i < num_core_aranges; ++i) {
      const VMRangeToFileOffset::Entry *entry =
          m_core_aranges.GetEntryAtIndex(i);
      lldb::addr_t section_vm_addr_start = entry->GetRangeBase();
      lldb::addr_t section_vm_addr_end = entry->GetRangeEnd();
      for (lldb::addr_t section_vm_addr = section_vm_addr_start;
           section_vm_addr < section_vm_addr_end; section_vm_addr += 0x1000) {
        GetDynamicLoaderAddress(section_vm_addr);
      }
    }
  }

  if (!found_main_binary_definitively &&
      m_mach_kernel_addr != LLDB_INVALID_ADDRESS) {
    // In the case of multiple kernel images found in the core file via
    // exhaustive search, we may not pick the correct one.  See if the
    // DynamicLoaderDarwinKernel's search heuristics might identify the correct
    // one. Most of the time, I expect the address from SearchForDarwinKernel()
    // will be the same as the address we found via exhaustive search.

    if (!GetTarget().GetArchitecture().IsValid() && m_core_module_sp.get()) {
      GetTarget().SetArchitecture(m_core_module_sp->GetArchitecture());
    }

    // SearchForDarwinKernel will end up calling back into this this class in
    // the GetImageInfoAddress method which will give it the
    // m_mach_kernel_addr/m_dyld_addr it already has.  Save that aside and set
    // m_mach_kernel_addr/m_dyld_addr to an invalid address temporarily so
    // DynamicLoaderDarwinKernel does a real search for the kernel using its
    // own heuristics.

    addr_t saved_mach_kernel_addr = m_mach_kernel_addr;
    addr_t saved_user_dyld_addr = m_dyld_addr;
    m_mach_kernel_addr = LLDB_INVALID_ADDRESS;
    m_dyld_addr = LLDB_INVALID_ADDRESS;

    addr_t better_kernel_address =
        DynamicLoaderDarwinKernel::SearchForDarwinKernel(this);

    m_mach_kernel_addr = saved_mach_kernel_addr;
    m_dyld_addr = saved_user_dyld_addr;

    if (better_kernel_address != LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log, "ProcessMachCore::DoLoadCore: Using the kernel address "
                     "from DynamicLoaderDarwinKernel");
      m_mach_kernel_addr = better_kernel_address;
    }
  }

  // If we found both a user-process dyld and a kernel binary, we need to
  // decide which to prefer.
  if (GetCorefilePreference() == eKernelCorefile) {
    if (m_mach_kernel_addr != LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log,
                "ProcessMachCore::DoLoadCore: Using kernel corefile image "
                "at 0x%" PRIx64,
                m_mach_kernel_addr);
      m_dyld_plugin_name = DynamicLoaderDarwinKernel::GetPluginNameStatic();
    } else if (m_dyld_addr != LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log,
                "ProcessMachCore::DoLoadCore: Using user process dyld "
                "image at 0x%" PRIx64,
                m_dyld_addr);
      m_dyld_plugin_name = DynamicLoaderMacOSXDYLD::GetPluginNameStatic();
    }
  } else {
    if (m_dyld_addr != LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log,
                "ProcessMachCore::DoLoadCore: Using user process dyld "
                "image at 0x%" PRIx64,
                m_dyld_addr);
      m_dyld_plugin_name = DynamicLoaderMacOSXDYLD::GetPluginNameStatic();
    } else if (m_mach_kernel_addr != LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log,
                "ProcessMachCore::DoLoadCore: Using kernel corefile image "
                "at 0x%" PRIx64,
                m_mach_kernel_addr);
      m_dyld_plugin_name = DynamicLoaderDarwinKernel::GetPluginNameStatic();
    }
  }

  if (m_dyld_plugin_name != DynamicLoaderMacOSXDYLD::GetPluginNameStatic()) {
    // For non-user process core files, the permissions on the core file
    // segments are usually meaningless, they may be just "read", because we're
    // dealing with kernel coredumps or early startup coredumps and the dumper
    // is grabbing pages of memory without knowing what they are.  If they
    // aren't marked as "executable", that can break the unwinder which will
    // check a pc value to see if it is in an executable segment and stop the
    // backtrace early if it is not ("executable" and "unknown" would both be
    // fine, but "not executable" will break the unwinder).
    size_t core_range_infos_size = m_core_range_infos.GetSize();
    for (size_t i = 0; i < core_range_infos_size; i++) {
      VMRangeToPermissions::Entry *ent =
          m_core_range_infos.GetMutableEntryAtIndex(i);
      ent->data = lldb::ePermissionsReadable | lldb::ePermissionsExecutable;
    }
  }

  // Even if the architecture is set in the target, we need to override it to
  // match the core file which is always single arch.
  ArchSpec arch(m_core_module_sp->GetArchitecture());
  if (arch.GetCore() == ArchSpec::eCore_x86_32_i486) {
    arch = Platform::GetAugmentedArchSpec(GetTarget().GetPlatform().get(), "i386");
  }
  if (arch.IsValid())
    GetTarget().SetArchitecture(arch);

  return error;
}

lldb_private::DynamicLoader *ProcessMachCore::GetDynamicLoader() {
  if (m_dyld_up.get() == nullptr)
    m_dyld_up.reset(DynamicLoader::FindPlugin(
        this, m_dyld_plugin_name.IsEmpty() ? nullptr
                                           : m_dyld_plugin_name.GetCString()));
  return m_dyld_up.get();
}

bool ProcessMachCore::UpdateThreadList(ThreadList &old_thread_list,
                                       ThreadList &new_thread_list) {
  if (old_thread_list.GetSize(false) == 0) {
    // Make up the thread the first time this is called so we can setup our one
    // and only core thread state.
    ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();

    if (core_objfile) {
      const uint32_t num_threads = core_objfile->GetNumThreadContexts();
      for (lldb::tid_t tid = 0; tid < num_threads; ++tid) {
        ThreadSP thread_sp(new ThreadMachCore(*this, tid));
        new_thread_list.AddThread(thread_sp);
      }
    }
  } else {
    const uint32_t num_threads = old_thread_list.GetSize(false);
    for (uint32_t i = 0; i < num_threads; ++i)
      new_thread_list.AddThread(old_thread_list.GetThreadAtIndex(i, false));
  }
  return new_thread_list.GetSize(false) > 0;
}

void ProcessMachCore::RefreshStateAfterStop() {
  // Let all threads recover from stopping and do any clean up based on the
  // previous thread state (if any).
  m_thread_list.RefreshStateAfterStop();
  // SetThreadStopInfo (m_last_stop_packet);
}

Status ProcessMachCore::DoDestroy() { return Status(); }

// Process Queries

bool ProcessMachCore::IsAlive() { return true; }

bool ProcessMachCore::WarnBeforeDetach() const { return false; }

// Process Memory
size_t ProcessMachCore::ReadMemory(addr_t addr, void *buf, size_t size,
                                   Status &error) {
  // Don't allow the caching that lldb_private::Process::ReadMemory does since
  // in core files we have it all cached our our core file anyway.
  return DoReadMemory(addr, buf, size, error);
}

size_t ProcessMachCore::DoReadMemory(addr_t addr, void *buf, size_t size,
                                     Status &error) {
  ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();
  size_t bytes_read = 0;

  if (core_objfile) {
    // Segments are not always contiguous in mach-o core files. We have core
    // files that have segments like:
    //            Address    Size       File off   File size
    //            ---------- ---------- ---------- ----------
    // LC_SEGMENT 0x000f6000 0x00001000 0x1d509ee8 0x00001000 --- ---   0
    // 0x00000000 __TEXT LC_SEGMENT 0x0f600000 0x00100000 0x1d50aee8 0x00100000
    // --- ---   0 0x00000000 __TEXT LC_SEGMENT 0x000f7000 0x00001000
    // 0x1d60aee8 0x00001000 --- ---   0 0x00000000 __TEXT
    //
    // Any if the user executes the following command:
    //
    // (lldb) mem read 0xf6ff0
    //
    // We would attempt to read 32 bytes from 0xf6ff0 but would only get 16
    // unless we loop through consecutive memory ranges that are contiguous in
    // the address space, but not in the file data.
    while (bytes_read < size) {
      const addr_t curr_addr = addr + bytes_read;
      const VMRangeToFileOffset::Entry *core_memory_entry =
          m_core_aranges.FindEntryThatContains(curr_addr);

      if (core_memory_entry) {
        const addr_t offset = curr_addr - core_memory_entry->GetRangeBase();
        const addr_t bytes_left = core_memory_entry->GetRangeEnd() - curr_addr;
        const size_t bytes_to_read =
            std::min(size - bytes_read, (size_t)bytes_left);
        const size_t curr_bytes_read = core_objfile->CopyData(
            core_memory_entry->data.GetRangeBase() + offset, bytes_to_read,
            (char *)buf + bytes_read);
        if (curr_bytes_read == 0)
          break;
        bytes_read += curr_bytes_read;
      } else {
        // Only set the error if we didn't read any bytes
        if (bytes_read == 0)
          error.SetErrorStringWithFormat(
              "core file does not contain 0x%" PRIx64, curr_addr);
        break;
      }
    }
  }

  return bytes_read;
}

Status ProcessMachCore::GetMemoryRegionInfo(addr_t load_addr,
                                            MemoryRegionInfo &region_info) {
  region_info.Clear();
  const VMRangeToPermissions::Entry *permission_entry =
      m_core_range_infos.FindEntryThatContainsOrFollows(load_addr);
  if (permission_entry) {
    if (permission_entry->Contains(load_addr)) {
      region_info.GetRange().SetRangeBase(permission_entry->GetRangeBase());
      region_info.GetRange().SetRangeEnd(permission_entry->GetRangeEnd());
      const Flags permissions(permission_entry->data);
      region_info.SetReadable(permissions.Test(ePermissionsReadable)
                                  ? MemoryRegionInfo::eYes
                                  : MemoryRegionInfo::eNo);
      region_info.SetWritable(permissions.Test(ePermissionsWritable)
                                  ? MemoryRegionInfo::eYes
                                  : MemoryRegionInfo::eNo);
      region_info.SetExecutable(permissions.Test(ePermissionsExecutable)
                                    ? MemoryRegionInfo::eYes
                                    : MemoryRegionInfo::eNo);
      region_info.SetMapped(MemoryRegionInfo::eYes);
    } else if (load_addr < permission_entry->GetRangeBase()) {
      region_info.GetRange().SetRangeBase(load_addr);
      region_info.GetRange().SetRangeEnd(permission_entry->GetRangeBase());
      region_info.SetReadable(MemoryRegionInfo::eNo);
      region_info.SetWritable(MemoryRegionInfo::eNo);
      region_info.SetExecutable(MemoryRegionInfo::eNo);
      region_info.SetMapped(MemoryRegionInfo::eNo);
    }
    return Status();
  }

  region_info.GetRange().SetRangeBase(load_addr);
  region_info.GetRange().SetRangeEnd(LLDB_INVALID_ADDRESS);
  region_info.SetReadable(MemoryRegionInfo::eNo);
  region_info.SetWritable(MemoryRegionInfo::eNo);
  region_info.SetExecutable(MemoryRegionInfo::eNo);
  region_info.SetMapped(MemoryRegionInfo::eNo);
  return Status();
}

void ProcessMachCore::Clear() { m_thread_list.Clear(); }

void ProcessMachCore::Initialize() {
  static llvm::once_flag g_once_flag;

  llvm::call_once(g_once_flag, []() {
    PluginManager::RegisterPlugin(GetPluginNameStatic(),
                                  GetPluginDescriptionStatic(), CreateInstance);
  });
}

addr_t ProcessMachCore::GetImageInfoAddress() {
  // If we found both a user-process dyld and a kernel binary, we need to
  // decide which to prefer.
  if (GetCorefilePreference() == eKernelCorefile) {
    if (m_mach_kernel_addr != LLDB_INVALID_ADDRESS) {
      return m_mach_kernel_addr;
    }
    return m_dyld_addr;
  } else {
    if (m_dyld_addr != LLDB_INVALID_ADDRESS) {
      return m_dyld_addr;
    }
    return m_mach_kernel_addr;
  }
}

lldb_private::ObjectFile *ProcessMachCore::GetCoreObjectFile() {
  return m_core_module_sp->GetObjectFile();
}