xref: /art/patchoat/patchoat.cc

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "patchoat.h"

#include <stdio.h>
#include <stdlib.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <unistd.h>

#include <string>
#include <vector>

#include "base/scoped_flock.h"
#include "base/stringpiece.h"
#include "base/stringprintf.h"
#include "elf_utils.h"
#include "elf_file.h"
#include "gc/space/image_space.h"
#include "image.h"
#include "instruction_set.h"
#include "mirror/art_field.h"
#include "mirror/art_field-inl.h"
#include "mirror/art_method.h"
#include "mirror/art_method-inl.h"
#include "mirror/object.h"
#include "mirror/object-inl.h"
#include "mirror/reference.h"
#include "noop_compiler_callbacks.h"
#include "offsets.h"
#include "os.h"
#include "runtime.h"
#include "scoped_thread_state_change.h"
#include "thread.h"
#include "utils.h"

namespace art {

static InstructionSet ElfISAToInstructionSet(Elf32_Word isa) {
  switch (isa) {
    case EM_ARM:
      return kArm;
    case EM_AARCH64:
      return kArm64;
    case EM_386:
      return kX86;
    case EM_X86_64:
      return kX86_64;
    case EM_MIPS:
      return kMips;
    default:
      return kNone;
  }
}

static bool LocationToFilename(const std::string& location, InstructionSet isa,
                               std::string* filename) {
  bool has_system = false;
  bool has_cache = false;
  // image_location = /system/framework/boot.art
  // system_image_location = /system/framework/<image_isa>/boot.art
  std::string system_filename(GetSystemImageFilename(location.c_str(), isa));
  if (OS::FileExists(system_filename.c_str())) {
    has_system = true;
  }

  bool have_android_data = false;
  bool dalvik_cache_exists = false;
  bool is_global_cache = false;
  std::string dalvik_cache;
  GetDalvikCache(GetInstructionSetString(isa), false, &dalvik_cache,
                 &have_android_data, &dalvik_cache_exists, &is_global_cache);

  std::string cache_filename;
  if (have_android_data && dalvik_cache_exists) {
    // Always set output location even if it does not exist,
    // so that the caller knows where to create the image.
    //
    // image_location = /system/framework/boot.art
    // *image_filename = /data/dalvik-cache/<image_isa>/boot.art
    std::string error_msg;
    if (GetDalvikCacheFilename(location.c_str(), dalvik_cache.c_str(),
                               &cache_filename, &error_msg)) {
      has_cache = true;
    }
  }
  if (has_system) {
    *filename = system_filename;
    return true;
  } else if (has_cache) {
    *filename = cache_filename;
    return true;
  } else {
    return false;
  }
}

bool PatchOat::Patch(const std::string& image_location, off_t delta,
                     File* output_image, InstructionSet isa,
                     TimingLogger* timings) {
  CHECK(Runtime::Current() == nullptr);
  CHECK(output_image != nullptr);
  CHECK_GE(output_image->Fd(), 0);
  CHECK(!image_location.empty()) << "image file must have a filename.";
  CHECK_NE(isa, kNone);

  TimingLogger::ScopedTiming t("Runtime Setup", timings);
  const char *isa_name = GetInstructionSetString(isa);
  std::string image_filename;
  if (!LocationToFilename(image_location, isa, &image_filename)) {
    LOG(ERROR) << "Unable to find image at location " << image_location;
    return false;
  }
  std::unique_ptr<File> input_image(OS::OpenFileForReading(image_filename.c_str()));
  if (input_image.get() == nullptr) {
    LOG(ERROR) << "unable to open input image file at " << image_filename
               << " for location " << image_location;
    return false;
  }
  int64_t image_len = input_image->GetLength();
  if (image_len < 0) {
    LOG(ERROR) << "Error while getting image length";
    return false;
  }
  ImageHeader image_header;
  if (sizeof(image_header) != input_image->Read(reinterpret_cast<char*>(&image_header),
                                              sizeof(image_header), 0)) {
    LOG(ERROR) << "Unable to read image header from image file " << input_image->GetPath();
    return false;
  }

  // Set up the runtime
  RuntimeOptions options;
  NoopCompilerCallbacks callbacks;
  options.push_back(std::make_pair("compilercallbacks", &callbacks));
  std::string img = "-Ximage:" + image_location;
  options.push_back(std::make_pair(img.c_str(), nullptr));
  options.push_back(std::make_pair("imageinstructionset", reinterpret_cast<const void*>(isa_name)));
  if (!Runtime::Create(options, false)) {
    LOG(ERROR) << "Unable to initialize runtime";
    return false;
  }
  // Runtime::Create acquired the mutator_lock_ that is normally given away when we Runtime::Start,
  // give it away now and then switch to a more manageable ScopedObjectAccess.
  Thread::Current()->TransitionFromRunnableToSuspended(kNative);
  ScopedObjectAccess soa(Thread::Current());

  t.NewTiming("Image and oat Patching setup");
  // Create the map where we will write the image patches to.
  std::string error_msg;
  std::unique_ptr<MemMap> image(MemMap::MapFile(image_len, PROT_READ | PROT_WRITE, MAP_PRIVATE,
                                                input_image->Fd(), 0,
                                                input_image->GetPath().c_str(),
                                                &error_msg));
  if (image.get() == nullptr) {
    LOG(ERROR) << "unable to map image file " << input_image->GetPath() << " : " << error_msg;
    return false;
  }
  gc::space::ImageSpace* ispc = Runtime::Current()->GetHeap()->GetImageSpace();

  PatchOat p(image.release(), ispc->GetLiveBitmap(), ispc->GetMemMap(),
             delta, timings);
  t.NewTiming("Patching files");
  if (!p.PatchImage()) {
    LOG(ERROR) << "Failed to patch image file " << input_image->GetPath();
    return false;
  }

  t.NewTiming("Writing files");
  if (!p.WriteImage(output_image)) {
    return false;
  }
  return true;
}

bool PatchOat::Patch(const File* input_oat, const std::string& image_location, off_t delta,
                     File* output_oat, File* output_image, InstructionSet isa,
                     TimingLogger* timings) {
  CHECK(Runtime::Current() == nullptr);
  CHECK(output_image != nullptr);
  CHECK_GE(output_image->Fd(), 0);
  CHECK(input_oat != nullptr);
  CHECK(output_oat != nullptr);
  CHECK_GE(input_oat->Fd(), 0);
  CHECK_GE(output_oat->Fd(), 0);
  CHECK(!image_location.empty()) << "image file must have a filename.";

  TimingLogger::ScopedTiming t("Runtime Setup", timings);

  if (isa == kNone) {
    Elf32_Ehdr elf_hdr;
    if (sizeof(elf_hdr) != input_oat->Read(reinterpret_cast<char*>(&elf_hdr), sizeof(elf_hdr), 0)) {
      LOG(ERROR) << "unable to read elf header";
      return false;
    }
    isa = ElfISAToInstructionSet(elf_hdr.e_machine);
  }
  const char* isa_name = GetInstructionSetString(isa);
  std::string image_filename;
  if (!LocationToFilename(image_location, isa, &image_filename)) {
    LOG(ERROR) << "Unable to find image at location " << image_location;
    return false;
  }
  std::unique_ptr<File> input_image(OS::OpenFileForReading(image_filename.c_str()));
  if (input_image.get() == nullptr) {
    LOG(ERROR) << "unable to open input image file at " << image_filename
               << " for location " << image_location;
    return false;
  }
  int64_t image_len = input_image->GetLength();
  if (image_len < 0) {
    LOG(ERROR) << "Error while getting image length";
    return false;
  }
  ImageHeader image_header;
  if (sizeof(image_header) != input_image->Read(reinterpret_cast<char*>(&image_header),
                                              sizeof(image_header), 0)) {
    LOG(ERROR) << "Unable to read image header from image file " << input_image->GetPath();
  }

  // Set up the runtime
  RuntimeOptions options;
  NoopCompilerCallbacks callbacks;
  options.push_back(std::make_pair("compilercallbacks", &callbacks));
  std::string img = "-Ximage:" + image_location;
  options.push_back(std::make_pair(img.c_str(), nullptr));
  options.push_back(std::make_pair("imageinstructionset", reinterpret_cast<const void*>(isa_name)));
  if (!Runtime::Create(options, false)) {
    LOG(ERROR) << "Unable to initialize runtime";
    return false;
  }
  // Runtime::Create acquired the mutator_lock_ that is normally given away when we Runtime::Start,
  // give it away now and then switch to a more manageable ScopedObjectAccess.
  Thread::Current()->TransitionFromRunnableToSuspended(kNative);
  ScopedObjectAccess soa(Thread::Current());

  t.NewTiming("Image and oat Patching setup");
  // Create the map where we will write the image patches to.
  std::string error_msg;
  std::unique_ptr<MemMap> image(MemMap::MapFile(image_len, PROT_READ | PROT_WRITE, MAP_PRIVATE,
                                                input_image->Fd(), 0,
                                                input_image->GetPath().c_str(),
                                                &error_msg));
  if (image.get() == nullptr) {
    LOG(ERROR) << "unable to map image file " << input_image->GetPath() << " : " << error_msg;
    return false;
  }
  gc::space::ImageSpace* ispc = Runtime::Current()->GetHeap()->GetImageSpace();

  std::unique_ptr<ElfFile> elf(ElfFile::Open(const_cast<File*>(input_oat),
                                             PROT_READ | PROT_WRITE, MAP_PRIVATE, &error_msg));
  if (elf.get() == nullptr) {
    LOG(ERROR) << "unable to open oat file " << input_oat->GetPath() << " : " << error_msg;
    return false;
  }

  PatchOat p(elf.release(), image.release(), ispc->GetLiveBitmap(), ispc->GetMemMap(),
             delta, timings);
  t.NewTiming("Patching files");
  if (!p.PatchElf()) {
    LOG(ERROR) << "Failed to patch oat file " << input_oat->GetPath();
    return false;
  }
  if (!p.PatchImage()) {
    LOG(ERROR) << "Failed to patch image file " << input_image->GetPath();
    return false;
  }

  t.NewTiming("Writing files");
  if (!p.WriteElf(output_oat)) {
    return false;
  }
  if (!p.WriteImage(output_image)) {
    return false;
  }
  return true;
}

bool PatchOat::WriteElf(File* out) {
  TimingLogger::ScopedTiming t("Writing Elf File", timings_);

  CHECK(oat_file_.get() != nullptr);
  CHECK(out != nullptr);
  size_t expect = oat_file_->Size();
  if (out->WriteFully(reinterpret_cast<char*>(oat_file_->Begin()), expect) &&
      out->SetLength(expect) == 0) {
    return true;
  } else {
    LOG(ERROR) << "Writing to oat file " << out->GetPath() << " failed.";
    return false;
  }
}

bool PatchOat::WriteImage(File* out) {
  TimingLogger::ScopedTiming t("Writing image File", timings_);
  std::string error_msg;

  ScopedFlock img_flock;
  img_flock.Init(out, &error_msg);

  CHECK(image_ != nullptr);
  CHECK(out != nullptr);
  size_t expect = image_->Size();
  if (out->WriteFully(reinterpret_cast<char*>(image_->Begin()), expect) &&
      out->SetLength(expect) == 0) {
    return true;
  } else {
    LOG(ERROR) << "Writing to image file " << out->GetPath() << " failed.";
    return false;
  }
}

bool PatchOat::PatchImage() {
  ImageHeader* image_header = reinterpret_cast<ImageHeader*>(image_->Begin());
  CHECK_GT(image_->Size(), sizeof(ImageHeader));
  // These are the roots from the original file.
  mirror::Object* img_roots = image_header->GetImageRoots();
  image_header->RelocateImage(delta_);

  VisitObject(img_roots);
  if (!image_header->IsValid()) {
    LOG(ERROR) << "reloction renders image header invalid";
    return false;
  }

  {
    TimingLogger::ScopedTiming t("Walk Bitmap", timings_);
    // Walk the bitmap.
    WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
    bitmap_->Walk(PatchOat::BitmapCallback, this);
  }
  return true;
}

bool PatchOat::InHeap(mirror::Object* o) {
  uintptr_t begin = reinterpret_cast<uintptr_t>(heap_->Begin());
  uintptr_t end = reinterpret_cast<uintptr_t>(heap_->End());
  uintptr_t obj = reinterpret_cast<uintptr_t>(o);
  return o == nullptr || (begin <= obj && obj < end);
}

void PatchOat::PatchVisitor::operator() (mirror::Object* obj, MemberOffset off,
                                         bool is_static_unused) const {
  mirror::Object* referent = obj->GetFieldObject<mirror::Object, kVerifyNone>(off);
  DCHECK(patcher_->InHeap(referent)) << "Referent is not in the heap.";
  mirror::Object* moved_object = patcher_->RelocatedAddressOf(referent);
  copy_->SetFieldObjectWithoutWriteBarrier<false, true, kVerifyNone>(off, moved_object);
}

void PatchOat::PatchVisitor::operator() (mirror::Class* cls, mirror::Reference* ref) const {
  MemberOffset off = mirror::Reference::ReferentOffset();
  mirror::Object* referent = ref->GetReferent();
  DCHECK(patcher_->InHeap(referent)) << "Referent is not in the heap.";
  mirror::Object* moved_object = patcher_->RelocatedAddressOf(referent);
  copy_->SetFieldObjectWithoutWriteBarrier<false, true, kVerifyNone>(off, moved_object);
}

mirror::Object* PatchOat::RelocatedCopyOf(mirror::Object* obj) {
  if (obj == nullptr) {
    return nullptr;
  }
  DCHECK_GT(reinterpret_cast<uintptr_t>(obj), reinterpret_cast<uintptr_t>(heap_->Begin()));
  DCHECK_LT(reinterpret_cast<uintptr_t>(obj), reinterpret_cast<uintptr_t>(heap_->End()));
  uintptr_t heap_off =
      reinterpret_cast<uintptr_t>(obj) - reinterpret_cast<uintptr_t>(heap_->Begin());
  DCHECK_LT(heap_off, image_->Size());
  return reinterpret_cast<mirror::Object*>(image_->Begin() + heap_off);
}

mirror::Object* PatchOat::RelocatedAddressOf(mirror::Object* obj) {
  if (obj == nullptr) {
    return nullptr;
  } else {
    return reinterpret_cast<mirror::Object*>(reinterpret_cast<byte*>(obj) + delta_);
  }
}

// Called by BitmapCallback
void PatchOat::VisitObject(mirror::Object* object) {
  mirror::Object* copy = RelocatedCopyOf(object);
  CHECK(copy != nullptr);
  if (kUseBakerOrBrooksReadBarrier) {
    object->AssertReadBarrierPointer();
    if (kUseBrooksReadBarrier) {
      mirror::Object* moved_to = RelocatedAddressOf(object);
      copy->SetReadBarrierPointer(moved_to);
      DCHECK_EQ(copy->GetReadBarrierPointer(), moved_to);
    }
  }
  PatchOat::PatchVisitor visitor(this, copy);
  object->VisitReferences<true, kVerifyNone>(visitor, visitor);
  if (object->IsArtMethod<kVerifyNone>()) {
    FixupMethod(static_cast<mirror::ArtMethod*>(object),
                static_cast<mirror::ArtMethod*>(copy));
  }
}

void PatchOat::FixupMethod(mirror::ArtMethod* object, mirror::ArtMethod* copy) {
  // Just update the entry points if it looks like we should.
  // TODO: sanity check all the pointers' values
  uintptr_t portable = reinterpret_cast<uintptr_t>(
      object->GetEntryPointFromPortableCompiledCode<kVerifyNone>());
  if (portable != 0) {
    copy->SetEntryPointFromPortableCompiledCode(reinterpret_cast<void*>(portable + delta_));
  }
  uintptr_t quick= reinterpret_cast<uintptr_t>(
      object->GetEntryPointFromQuickCompiledCode<kVerifyNone>());
  if (quick != 0) {
    copy->SetEntryPointFromQuickCompiledCode(reinterpret_cast<void*>(quick + delta_));
  }
  uintptr_t interpreter = reinterpret_cast<uintptr_t>(
      object->GetEntryPointFromInterpreter<kVerifyNone>());
  if (interpreter != 0) {
    copy->SetEntryPointFromInterpreter(
        reinterpret_cast<mirror::EntryPointFromInterpreter*>(interpreter + delta_));
  }

  uintptr_t native_method = reinterpret_cast<uintptr_t>(object->GetNativeMethod());
  if (native_method != 0) {
    copy->SetNativeMethod(reinterpret_cast<void*>(native_method + delta_));
  }

  uintptr_t native_gc_map = reinterpret_cast<uintptr_t>(object->GetNativeGcMap());
  if (native_gc_map != 0) {
    copy->SetNativeGcMap(reinterpret_cast<uint8_t*>(native_gc_map + delta_));
  }
}

bool PatchOat::Patch(File* input_oat, off_t delta, File* output_oat, TimingLogger* timings) {
  CHECK(input_oat != nullptr);
  CHECK(output_oat != nullptr);
  CHECK_GE(input_oat->Fd(), 0);
  CHECK_GE(output_oat->Fd(), 0);
  TimingLogger::ScopedTiming t("Setup Oat File Patching", timings);

  std::string error_msg;
  std::unique_ptr<ElfFile> elf(ElfFile::Open(const_cast<File*>(input_oat),
                                             PROT_READ | PROT_WRITE, MAP_PRIVATE, &error_msg));
  if (elf.get() == nullptr) {
    LOG(ERROR) << "unable to open oat file " << input_oat->GetPath() << " : " << error_msg;
    return false;
  }

  PatchOat p(elf.release(), delta, timings);
  t.NewTiming("Patch Oat file");
  if (!p.PatchElf()) {
    return false;
  }

  t.NewTiming("Writing oat file");
  if (!p.WriteElf(output_oat)) {
    return false;
  }
  return true;
}

template <typename ptr_t>
bool PatchOat::CheckOatFile(const Elf32_Shdr& patches_sec) {
  if (patches_sec.sh_type != SHT_OAT_PATCH) {
    return false;
  }
  ptr_t* patches = reinterpret_cast<ptr_t*>(oat_file_->Begin() + patches_sec.sh_offset);
  ptr_t* patches_end = patches + (patches_sec.sh_size / sizeof(ptr_t));
  Elf32_Shdr* oat_data_sec = oat_file_->FindSectionByName(".rodata");
  Elf32_Shdr* oat_text_sec = oat_file_->FindSectionByName(".text");
  if (oat_data_sec == nullptr) {
    return false;
  }
  if (oat_text_sec == nullptr) {
    return false;
  }
  if (oat_text_sec->sh_offset <= oat_data_sec->sh_offset) {
    return false;
  }

  for (; patches < patches_end; patches++) {
    if (oat_text_sec->sh_size <= *patches) {
      return false;
    }
  }

  return true;
}

bool PatchOat::PatchOatHeader() {
  Elf32_Shdr *rodata_sec = oat_file_->FindSectionByName(".rodata");
  if (rodata_sec == nullptr) {
    return false;
  }
  OatHeader* oat_header = reinterpret_cast<OatHeader*>(oat_file_->Begin() + rodata_sec->sh_offset);
  if (!oat_header->IsValid()) {
    LOG(ERROR) << "Elf file " << oat_file_->GetFile().GetPath() << " has an invalid oat header";
    return false;
  }
  oat_header->RelocateOat(delta_);
  return true;
}

bool PatchOat::PatchElf() {
  TimingLogger::ScopedTiming t("Fixup Elf Text Section", timings_);
  if (!PatchTextSection()) {
    return false;
  }

  if (!PatchOatHeader()) {
    return false;
  }

  bool need_fixup = false;
  t.NewTiming("Fixup Elf Headers");
  // Fixup Phdr's
  for (unsigned int i = 0; i < oat_file_->GetProgramHeaderNum(); i++) {
    Elf32_Phdr* hdr = oat_file_->GetProgramHeader(i);
    CHECK(hdr != nullptr);
    if (hdr->p_vaddr != 0 && hdr->p_vaddr != hdr->p_offset) {
      need_fixup = true;
      hdr->p_vaddr += delta_;
    }
    if (hdr->p_paddr != 0 && hdr->p_paddr != hdr->p_offset) {
      need_fixup = true;
      hdr->p_paddr += delta_;
    }
  }
  if (!need_fixup) {
    // This was never passed through ElfFixup so all headers/symbols just have their offset as
    // their addr. Therefore we do not need to update these parts.
    return true;
  }
  t.NewTiming("Fixup Section Headers");
  for (unsigned int i = 0; i < oat_file_->GetSectionHeaderNum(); i++) {
    Elf32_Shdr* hdr = oat_file_->GetSectionHeader(i);
    CHECK(hdr != nullptr);
    if (hdr->sh_addr != 0) {
      hdr->sh_addr += delta_;
    }
  }

  t.NewTiming("Fixup Dynamics");
  for (Elf32_Word i = 0; i < oat_file_->GetDynamicNum(); i++) {
    Elf32_Dyn& dyn = oat_file_->GetDynamic(i);
    if (IsDynamicSectionPointer(dyn.d_tag, oat_file_->GetHeader().e_machine)) {
      dyn.d_un.d_ptr += delta_;
    }
  }

  t.NewTiming("Fixup Elf Symbols");
  // Fixup dynsym
  Elf32_Shdr* dynsym_sec = oat_file_->FindSectionByName(".dynsym");
  CHECK(dynsym_sec != nullptr);
  if (!PatchSymbols(dynsym_sec)) {
    return false;
  }

  // Fixup symtab
  Elf32_Shdr* symtab_sec = oat_file_->FindSectionByName(".symtab");
  if (symtab_sec != nullptr) {
    if (!PatchSymbols(symtab_sec)) {
      return false;
    }
  }

  t.NewTiming("Fixup Debug Sections");
  if (!oat_file_->FixupDebugSections(delta_)) {
    return false;
  }

  return true;
}

bool PatchOat::PatchSymbols(Elf32_Shdr* section) {
  Elf32_Sym* syms = reinterpret_cast<Elf32_Sym*>(oat_file_->Begin() + section->sh_offset);
  const Elf32_Sym* last_sym =
      reinterpret_cast<Elf32_Sym*>(oat_file_->Begin() + section->sh_offset + section->sh_size);
  CHECK_EQ(section->sh_size % sizeof(Elf32_Sym), 0u)
      << "Symtab section size is not multiple of symbol size";
  for (; syms < last_sym; syms++) {
    uint8_t sttype = ELF32_ST_TYPE(syms->st_info);
    Elf32_Word shndx = syms->st_shndx;
    if (shndx != SHN_ABS && shndx != SHN_COMMON && shndx != SHN_UNDEF &&
        (sttype == STT_FUNC || sttype == STT_OBJECT)) {
      CHECK_NE(syms->st_value, 0u);
      syms->st_value += delta_;
    }
  }
  return true;
}

bool PatchOat::PatchTextSection() {
  Elf32_Shdr* patches_sec = oat_file_->FindSectionByName(".oat_patches");
  if (patches_sec == nullptr) {
    LOG(ERROR) << ".oat_patches section not found. Aborting patch";
    return false;
  }
  if (patches_sec->sh_type != SHT_OAT_PATCH) {
    LOG(ERROR) << "Unexpected type of .oat_patches";
    return false;
  }

  switch (patches_sec->sh_entsize) {
    case sizeof(uint32_t):
      return PatchTextSection<uint32_t>(*patches_sec);
    case sizeof(uint64_t):
      return PatchTextSection<uint64_t>(*patches_sec);
    default:
      LOG(ERROR) << ".oat_patches Entsize of " << patches_sec->sh_entsize << "bits "
                 << "is not valid";
      return false;
  }
}

template <typename ptr_t>
bool PatchOat::PatchTextSection(const Elf32_Shdr& patches_sec) {
  DCHECK(CheckOatFile<ptr_t>(patches_sec)) << "Oat file invalid";
  ptr_t* patches = reinterpret_cast<ptr_t*>(oat_file_->Begin() + patches_sec.sh_offset);
  ptr_t* patches_end = patches + (patches_sec.sh_size / sizeof(ptr_t));
  Elf32_Shdr* oat_text_sec = oat_file_->FindSectionByName(".text");
  CHECK(oat_text_sec != nullptr);
  byte* to_patch = oat_file_->Begin() + oat_text_sec->sh_offset;
  uintptr_t to_patch_end = reinterpret_cast<uintptr_t>(to_patch) + oat_text_sec->sh_size;

  for (; patches < patches_end; patches++) {
    CHECK_LT(*patches, oat_text_sec->sh_size) << "Bad Patch";
    uint32_t* patch_loc = reinterpret_cast<uint32_t*>(to_patch + *patches);
    CHECK_LT(reinterpret_cast<uintptr_t>(patch_loc), to_patch_end);
    *patch_loc += delta_;
  }
  return true;
}

static int orig_argc;
static char** orig_argv;

static std::string CommandLine() {
  std::vector<std::string> command;
  for (int i = 0; i < orig_argc; ++i) {
    command.push_back(orig_argv[i]);
  }
  return Join(command, ' ');
}

static void UsageErrorV(const char* fmt, va_list ap) {
  std::string error;
  StringAppendV(&error, fmt, ap);
  LOG(ERROR) << error;
}

static void UsageError(const char* fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  UsageErrorV(fmt, ap);
  va_end(ap);
}

static void Usage(const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  UsageErrorV(fmt, ap);
  va_end(ap);

  UsageError("Command: %s", CommandLine().c_str());
  UsageError("Usage: patchoat [options]...");
  UsageError("");
  UsageError("  --instruction-set=<isa>: Specifies the instruction set the patched code is");
  UsageError("      compiled for. Required if you use --input-oat-location");
  UsageError("");
  UsageError("  --input-oat-file=<file.oat>: Specifies the exact filename of the oat file to be");
  UsageError("      patched.");
  UsageError("");
  UsageError("  --input-oat-fd=<file-descriptor>: Specifies the file-descriptor of the oat file");
  UsageError("      to be patched.");
  UsageError("");
  UsageError("  --input-oat-location=<file.oat>: Specifies the 'location' to read the patched");
  UsageError("      oat file from. If used one must also supply the --instruction-set");
  UsageError("");
  UsageError("  --input-image-location=<file.art>: Specifies the 'location' of the image file to");
  UsageError("      be patched. If --instruction-set is not given it will use the instruction set");
  UsageError("      extracted from the --input-oat-file.");
  UsageError("");
  UsageError("  --output-oat-file=<file.oat>: Specifies the exact file to write the patched oat");
  UsageError("      file to.");
  UsageError("");
  UsageError("  --output-oat-fd=<file-descriptor>: Specifies the file-descriptor to write the");
  UsageError("      the patched oat file to.");
  UsageError("");
  UsageError("  --output-image-file=<file.art>: Specifies the exact file to write the patched");
  UsageError("      image file to.");
  UsageError("");
  UsageError("  --output-image-fd=<file-descriptor>: Specifies the file-descriptor to write the");
  UsageError("      the patched image file to.");
  UsageError("");
  UsageError("  --orig-base-offset=<original-base-offset>: Specify the base offset the input file");
  UsageError("      was compiled with. This is needed if one is specifying a --base-offset");
  UsageError("");
  UsageError("  --base-offset=<new-base-offset>: Specify the base offset we will repatch the");
  UsageError("      given files to use. This requires that --orig-base-offset is also given.");
  UsageError("");
  UsageError("  --base-offset-delta=<delta>: Specify the amount to change the old base-offset by.");
  UsageError("      This value may be negative.");
  UsageError("");
  UsageError("  --patched-image-file=<file.art>: Use the same patch delta as was used to patch");
  UsageError("      the given image file.");
  UsageError("");
  UsageError("  --patched-image-location=<file.art>: Use the same patch delta as was used to");
  UsageError("      patch the given image location. If used one must also specify the");
  UsageError("      --instruction-set flag. It will search for this image in the same way that");
  UsageError("      is done when loading one.");
  UsageError("");
  UsageError("  --lock-output: Obtain a flock on output oat file before starting.");
  UsageError("");
  UsageError("  --no-lock-output: Do not attempt to obtain a flock on output oat file.");
  UsageError("");
  UsageError("  --dump-timings: dump out patch timing information");
  UsageError("");
  UsageError("  --no-dump-timings: do not dump out patch timing information");
  UsageError("");

  exit(EXIT_FAILURE);
}

static bool ReadBaseDelta(const char* name, off_t* delta, std::string* error_msg) {
  CHECK(name != nullptr);
  CHECK(delta != nullptr);
  std::unique_ptr<File> file;
  if (OS::FileExists(name)) {
    file.reset(OS::OpenFileForReading(name));
    if (file.get() == nullptr) {
      *error_msg = "Failed to open file %s for reading";
      return false;
    }
  } else {
    *error_msg = "File %s does not exist";
    return false;
  }
  CHECK(file.get() != nullptr);
  ImageHeader hdr;
  if (sizeof(hdr) != file->Read(reinterpret_cast<char*>(&hdr), sizeof(hdr), 0)) {
    *error_msg = "Failed to read file %s";
    return false;
  }
  if (!hdr.IsValid()) {
    *error_msg = "%s does not contain a valid image header.";
    return false;
  }
  *delta = hdr.GetPatchDelta();
  return true;
}

static File* CreateOrOpen(const char* name, bool* created) {
  if (OS::FileExists(name)) {
    *created = false;
    return OS::OpenFileReadWrite(name);
  } else {
    *created = true;
    std::unique_ptr<File> f(OS::CreateEmptyFile(name));
    if (f.get() != nullptr) {
      if (fchmod(f->Fd(), 0644) != 0) {
        PLOG(ERROR) << "Unable to make " << name << " world readable";
        unlink(name);
        return nullptr;
      }
    }
    return f.release();
  }
}

static int patchoat(int argc, char **argv) {
  InitLogging(argv);
  const bool debug = kIsDebugBuild;
  orig_argc = argc;
  orig_argv = argv;
  TimingLogger timings("patcher", false, false);

  InitLogging(argv);

  // Skip over the command name.
  argv++;
  argc--;

  if (argc == 0) {
    Usage("No arguments specified");
  }

  timings.StartTiming("Patchoat");

  // cmd line args
  bool isa_set = false;
  InstructionSet isa = kNone;
  std::string input_oat_filename;
  std::string input_oat_location;
  int input_oat_fd = -1;
  bool have_input_oat = false;
  std::string input_image_location;
  std::string output_oat_filename;
  int output_oat_fd = -1;
  bool have_output_oat = false;
  std::string output_image_filename;
  int output_image_fd = -1;
  bool have_output_image = false;
  uintptr_t base_offset = 0;
  bool base_offset_set = false;
  uintptr_t orig_base_offset = 0;
  bool orig_base_offset_set = false;
  off_t base_delta = 0;
  bool base_delta_set = false;
  std::string patched_image_filename;
  std::string patched_image_location;
  bool dump_timings = kIsDebugBuild;
  bool lock_output = true;

  for (int i = 0; i < argc; i++) {
    const StringPiece option(argv[i]);
    const bool log_options = false;
    if (log_options) {
      LOG(INFO) << "patchoat: option[" << i << "]=" << argv[i];
    }
    if (option.starts_with("--instruction-set=")) {
      isa_set = true;
      const char* isa_str = option.substr(strlen("--instruction-set=")).data();
      isa = GetInstructionSetFromString(isa_str);
      if (isa == kNone) {
        Usage("Unknown or invalid instruction set %s", isa_str);
      }
    } else if (option.starts_with("--input-oat-location=")) {
      if (have_input_oat) {
        Usage("Only one of --input-oat-file, --input-oat-location and --input-oat-fd may be used.");
      }
      have_input_oat = true;
      input_oat_location = option.substr(strlen("--input-oat-location=")).data();
    } else if (option.starts_with("--input-oat-file=")) {
      if (have_input_oat) {
        Usage("Only one of --input-oat-file, --input-oat-location and --input-oat-fd may be used.");
      }
      have_input_oat = true;
      input_oat_filename = option.substr(strlen("--input-oat-file=")).data();
    } else if (option.starts_with("--input-oat-fd=")) {
      if (have_input_oat) {
        Usage("Only one of --input-oat-file, --input-oat-location and --input-oat-fd may be used.");
      }
      have_input_oat = true;
      const char* oat_fd_str = option.substr(strlen("--input-oat-fd=")).data();
      if (!ParseInt(oat_fd_str, &input_oat_fd)) {
        Usage("Failed to parse --input-oat-fd argument '%s' as an integer", oat_fd_str);
      }
      if (input_oat_fd < 0) {
        Usage("--input-oat-fd pass a negative value %d", input_oat_fd);
      }
    } else if (option.starts_with("--input-image-location=")) {
      input_image_location = option.substr(strlen("--input-image-location=")).data();
    } else if (option.starts_with("--output-oat-file=")) {
      if (have_output_oat) {
        Usage("Only one of --output-oat-file, and --output-oat-fd may be used.");
      }
      have_output_oat = true;
      output_oat_filename = option.substr(strlen("--output-oat-file=")).data();
    } else if (option.starts_with("--output-oat-fd=")) {
      if (have_output_oat) {
        Usage("Only one of --output-oat-file, --output-oat-fd may be used.");
      }
      have_output_oat = true;
      const char* oat_fd_str = option.substr(strlen("--output-oat-fd=")).data();
      if (!ParseInt(oat_fd_str, &output_oat_fd)) {
        Usage("Failed to parse --output-oat-fd argument '%s' as an integer", oat_fd_str);
      }
      if (output_oat_fd < 0) {
        Usage("--output-oat-fd pass a negative value %d", output_oat_fd);
      }
    } else if (option.starts_with("--output-image-file=")) {
      if (have_output_image) {
        Usage("Only one of --output-image-file, and --output-image-fd may be used.");
      }
      have_output_image = true;
      output_image_filename = option.substr(strlen("--output-image-file=")).data();
    } else if (option.starts_with("--output-image-fd=")) {
      if (have_output_image) {
        Usage("Only one of --output-image-file, and --output-image-fd may be used.");
      }
      have_output_image = true;
      const char* image_fd_str = option.substr(strlen("--output-image-fd=")).data();
      if (!ParseInt(image_fd_str, &output_image_fd)) {
        Usage("Failed to parse --output-image-fd argument '%s' as an integer", image_fd_str);
      }
      if (output_image_fd < 0) {
        Usage("--output-image-fd pass a negative value %d", output_image_fd);
      }
    } else if (option.starts_with("--orig-base-offset=")) {
      const char* orig_base_offset_str = option.substr(strlen("--orig-base-offset=")).data();
      orig_base_offset_set = true;
      if (!ParseUint(orig_base_offset_str, &orig_base_offset)) {
        Usage("Failed to parse --orig-base-offset argument '%s' as an uintptr_t",
              orig_base_offset_str);
      }
    } else if (option.starts_with("--base-offset=")) {
      const char* base_offset_str = option.substr(strlen("--base-offset=")).data();
      base_offset_set = true;
      if (!ParseUint(base_offset_str, &base_offset)) {
        Usage("Failed to parse --base-offset argument '%s' as an uintptr_t", base_offset_str);
      }
    } else if (option.starts_with("--base-offset-delta=")) {
      const char* base_delta_str = option.substr(strlen("--base-offset-delta=")).data();
      base_delta_set = true;
      if (!ParseInt(base_delta_str, &base_delta)) {
        Usage("Failed to parse --base-offset-delta argument '%s' as an off_t", base_delta_str);
      }
    } else if (option.starts_with("--patched-image-location=")) {
      patched_image_location = option.substr(strlen("--patched-image-location=")).data();
    } else if (option.starts_with("--patched-image-file=")) {
      patched_image_filename = option.substr(strlen("--patched-image-file=")).data();
    } else if (option == "--lock-output") {
      lock_output = true;
    } else if (option == "--no-lock-output") {
      lock_output = false;
    } else if (option == "--dump-timings") {
      dump_timings = true;
    } else if (option == "--no-dump-timings") {
      dump_timings = false;
    } else {
      Usage("Unknown argument %s", option.data());
    }
  }

  {
    // Only 1 of these may be set.
    uint32_t cnt = 0;
    cnt += (base_delta_set) ? 1 : 0;
    cnt += (base_offset_set && orig_base_offset_set) ? 1 : 0;
    cnt += (!patched_image_filename.empty()) ? 1 : 0;
    cnt += (!patched_image_location.empty()) ? 1 : 0;
    if (cnt > 1) {
      Usage("Only one of --base-offset/--orig-base-offset, --base-offset-delta, "
            "--patched-image-filename or --patched-image-location may be used.");
    } else if (cnt == 0) {
      Usage("Must specify --base-offset-delta, --base-offset and --orig-base-offset, "
            "--patched-image-location or --patched-image-file");
    }
  }

  if (have_input_oat != have_output_oat) {
    Usage("Either both input and output oat must be supplied or niether must be.");
  }

  if ((!input_image_location.empty()) != have_output_image) {
    Usage("Either both input and output image must be supplied or niether must be.");
  }

  // We know we have both the input and output so rename for clarity.
  bool have_image_files = have_output_image;
  bool have_oat_files = have_output_oat;

  if (!have_oat_files && !have_image_files) {
    Usage("Must be patching either an oat or an image file or both.");
  }

  if (!have_oat_files && !isa_set) {
    Usage("Must include ISA if patching an image file without an oat file.");
  }

  if (!input_oat_location.empty()) {
    if (!isa_set) {
      Usage("specifying a location requires specifying an instruction set");
    }
    if (!LocationToFilename(input_oat_location, isa, &input_oat_filename)) {
      Usage("Unable to find filename for input oat location %s", input_oat_location.c_str());
    }
    if (debug) {
      LOG(INFO) << "Using input-oat-file " << input_oat_filename;
    }
  }
  if (!patched_image_location.empty()) {
    if (!isa_set) {
      Usage("specifying a location requires specifying an instruction set");
    }
    std::string system_filename;
    bool has_system = false;
    std::string cache_filename;
    bool has_cache = false;
    bool has_android_data_unused = false;
    bool is_global_cache = false;
    if (!gc::space::ImageSpace::FindImageFilename(patched_image_location.c_str(), isa,
                                                  &system_filename, &has_system, &cache_filename,
                                                  &has_android_data_unused, &has_cache,
                                                  &is_global_cache)) {
      Usage("Unable to determine image file for location %s", patched_image_location.c_str());
    }
    if (has_cache) {
      patched_image_filename = cache_filename;
    } else if (has_system) {
      LOG(WARNING) << "Only image file found was in /system for image location "
                   << patched_image_location;
      patched_image_filename = system_filename;
    } else {
      Usage("Unable to determine image file for location %s", patched_image_location.c_str());
    }
    if (debug) {
      LOG(INFO) << "Using patched-image-file " << patched_image_filename;
    }
  }

  if (!base_delta_set) {
    if (orig_base_offset_set && base_offset_set) {
      base_delta_set = true;
      base_delta = base_offset - orig_base_offset;
    } else if (!patched_image_filename.empty()) {
      base_delta_set = true;
      std::string error_msg;
      if (!ReadBaseDelta(patched_image_filename.c_str(), &base_delta, &error_msg)) {
        Usage(error_msg.c_str(), patched_image_filename.c_str());
      }
    } else {
      if (base_offset_set) {
        Usage("Unable to determine original base offset.");
      } else {
        Usage("Must supply a desired new offset or delta.");
      }
    }
  }

  if (!IsAligned<kPageSize>(base_delta)) {
    Usage("Base offset/delta must be alligned to a pagesize (0x%08x) boundary.", kPageSize);
  }

  // Do we need to cleanup output files if we fail?
  bool new_image_out = false;
  bool new_oat_out = false;

  std::unique_ptr<File> input_oat;
  std::unique_ptr<File> output_oat;
  std::unique_ptr<File> output_image;

  if (have_image_files) {
    CHECK(!input_image_location.empty());

    if (output_image_fd != -1) {
      if (output_image_filename.empty()) {
        output_image_filename = "output-image-file";
      }
      output_image.reset(new File(output_image_fd, output_image_filename));
    } else {
      CHECK(!output_image_filename.empty());
      output_image.reset(CreateOrOpen(output_image_filename.c_str(), &new_image_out));
    }
  } else {
    CHECK(output_image_filename.empty() && output_image_fd == -1 && input_image_location.empty());
  }

  if (have_oat_files) {
    if (input_oat_fd != -1) {
      if (input_oat_filename.empty()) {
        input_oat_filename = "input-oat-file";
      }
      input_oat.reset(new File(input_oat_fd, input_oat_filename));
    } else {
      CHECK(!input_oat_filename.empty());
      input_oat.reset(OS::OpenFileForReading(input_oat_filename.c_str()));
      if (input_oat.get() == nullptr) {
        LOG(ERROR) << "Could not open input oat file: " << strerror(errno);
      }
    }

    if (output_oat_fd != -1) {
      if (output_oat_filename.empty()) {
        output_oat_filename = "output-oat-file";
      }
      output_oat.reset(new File(output_oat_fd, output_oat_filename));
    } else {
      CHECK(!output_oat_filename.empty());
      output_oat.reset(CreateOrOpen(output_oat_filename.c_str(), &new_oat_out));
    }
  }

  auto cleanup = [&output_image_filename, &output_oat_filename,
                  &new_oat_out, &new_image_out, &timings, &dump_timings](bool success) {
    timings.EndTiming();
    if (!success) {
      if (new_oat_out) {
        CHECK(!output_oat_filename.empty());
        unlink(output_oat_filename.c_str());
      }
      if (new_image_out) {
        CHECK(!output_image_filename.empty());
        unlink(output_image_filename.c_str());
      }
    }
    if (dump_timings) {
      LOG(INFO) << Dumpable<TimingLogger>(timings);
    }
  };

  if ((have_oat_files && (input_oat.get() == nullptr || output_oat.get() == nullptr)) ||
      (have_image_files && output_image.get() == nullptr)) {
    cleanup(false);
    return EXIT_FAILURE;
  }

  ScopedFlock output_oat_lock;
  if (lock_output) {
    std::string error_msg;
    if (have_oat_files && !output_oat_lock.Init(output_oat.get(), &error_msg)) {
      LOG(ERROR) << "Unable to lock output oat " << output_image->GetPath() << ": " << error_msg;
      cleanup(false);
      return EXIT_FAILURE;
    }
  }

  if (debug) {
    LOG(INFO) << "moving offset by " << base_delta
              << " (0x" << std::hex << base_delta << ") bytes or "
              << std::dec << (base_delta/kPageSize) << " pages.";
  }

  bool ret;
  if (have_image_files && have_oat_files) {
    TimingLogger::ScopedTiming pt("patch image and oat", &timings);
    ret = PatchOat::Patch(input_oat.get(), input_image_location, base_delta,
                          output_oat.get(), output_image.get(), isa, &timings);
  } else if (have_oat_files) {
    TimingLogger::ScopedTiming pt("patch oat", &timings);
    ret = PatchOat::Patch(input_oat.get(), base_delta, output_oat.get(), &timings);
  } else {
    TimingLogger::ScopedTiming pt("patch image", &timings);
    CHECK(have_image_files);
    ret = PatchOat::Patch(input_image_location, base_delta, output_image.get(), isa, &timings);
  }
  cleanup(ret);
  return (ret) ? EXIT_SUCCESS : EXIT_FAILURE;
}

}  // namespace art

int main(int argc, char **argv) {
  return art::patchoat(argc, argv);
}