runtime/utils.cc

/*
 * Copyright (C) 2011 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 "utils.h"

#include <inttypes.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <memory>

#include "art_field-inl.h"
#include "art_method-inl.h"
#include "base/stl_util.h"
#include "base/unix_file/fd_file.h"
#include "dex_file-inl.h"
#include "dex_instruction.h"
#include "mirror/class-inl.h"
#include "mirror/class_loader.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "mirror/string.h"
#include "oat_quick_method_header.h"
#include "os.h"
#include "scoped_thread_state_change.h"
#include "utf-inl.h"

#if defined(__APPLE__)
#include "AvailabilityMacros.h"  // For MAC_OS_X_VERSION_MAX_ALLOWED
#include <sys/syscall.h>
#endif

#if defined(__linux__)
#include <linux/unistd.h>
#endif

namespace art {

static const uint8_t kBase64Map[256] = {
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,
  52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
  255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
    7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,  // NOLINT
   19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255,  // NOLINT
  255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
   37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,  // NOLINT
   49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,  // NOLINT
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255
};

uint8_t* DecodeBase64(const char* src, size_t* dst_size) {
  std::vector<uint8_t> tmp;
  uint32_t t = 0, y = 0;
  int g = 3;
  for (size_t i = 0; src[i] != '\0'; ++i) {
    uint8_t c = kBase64Map[src[i] & 0xFF];
    if (c == 255) continue;
    // the final = symbols are read and used to trim the remaining bytes
    if (c == 254) {
      c = 0;
      // prevent g < 0 which would potentially allow an overflow later
      if (--g < 0) {
        *dst_size = 0;
        return nullptr;
      }
    } else if (g != 3) {
      // we only allow = to be at the end
      *dst_size = 0;
      return nullptr;
    }
    t = (t << 6) | c;
    if (++y == 4) {
      tmp.push_back((t >> 16) & 255);
      if (g > 1) {
        tmp.push_back((t >> 8) & 255);
      }
      if (g > 2) {
        tmp.push_back(t & 255);
      }
      y = t = 0;
    }
  }
  if (y != 0) {
    *dst_size = 0;
    return nullptr;
  }
  std::unique_ptr<uint8_t[]> dst(new uint8_t[tmp.size()]);
  if (dst_size != nullptr) {
    *dst_size = tmp.size();
  } else {
    *dst_size = 0;
  }
  std::copy(tmp.begin(), tmp.end(), dst.get());
  return dst.release();
}

pid_t GetTid() {
#if defined(__APPLE__)
  uint64_t owner;
  CHECK_PTHREAD_CALL(pthread_threadid_np, (nullptr, &owner), __FUNCTION__);  // Requires Mac OS 10.6
  return owner;
#elif defined(__BIONIC__)
  return gettid();
#else
  return syscall(__NR_gettid);
#endif
}

std::string GetThreadName(pid_t tid) {
  std::string result;
  if (ReadFileToString(StringPrintf("/proc/self/task/%d/comm", tid), &result)) {
    result.resize(result.size() - 1);  // Lose the trailing '\n'.
  } else {
    result = "<unknown>";
  }
  return result;
}

void GetThreadStack(pthread_t thread, void** stack_base, size_t* stack_size, size_t* guard_size) {
#if defined(__APPLE__)
  *stack_size = pthread_get_stacksize_np(thread);
  void* stack_addr = pthread_get_stackaddr_np(thread);

  // Check whether stack_addr is the base or end of the stack.
  // (On Mac OS 10.7, it's the end.)
  int stack_variable;
  if (stack_addr > &stack_variable) {
    *stack_base = reinterpret_cast<uint8_t*>(stack_addr) - *stack_size;
  } else {
    *stack_base = stack_addr;
  }

  // This is wrong, but there doesn't seem to be a way to get the actual value on the Mac.
  pthread_attr_t attributes;
  CHECK_PTHREAD_CALL(pthread_attr_init, (&attributes), __FUNCTION__);
  CHECK_PTHREAD_CALL(pthread_attr_getguardsize, (&attributes, guard_size), __FUNCTION__);
  CHECK_PTHREAD_CALL(pthread_attr_destroy, (&attributes), __FUNCTION__);
#else
  pthread_attr_t attributes;
  CHECK_PTHREAD_CALL(pthread_getattr_np, (thread, &attributes), __FUNCTION__);
  CHECK_PTHREAD_CALL(pthread_attr_getstack, (&attributes, stack_base, stack_size), __FUNCTION__);
  CHECK_PTHREAD_CALL(pthread_attr_getguardsize, (&attributes, guard_size), __FUNCTION__);
  CHECK_PTHREAD_CALL(pthread_attr_destroy, (&attributes), __FUNCTION__);

#if defined(__GLIBC__)
  // If we're the main thread, check whether we were run with an unlimited stack. In that case,
  // glibc will have reported a 2GB stack for our 32-bit process, and our stack overflow detection
  // will be broken because we'll die long before we get close to 2GB.
  bool is_main_thread = (::art::GetTid() == getpid());
  if (is_main_thread) {
    rlimit stack_limit;
    if (getrlimit(RLIMIT_STACK, &stack_limit) == -1) {
      PLOG(FATAL) << "getrlimit(RLIMIT_STACK) failed";
    }
    if (stack_limit.rlim_cur == RLIM_INFINITY) {
      size_t old_stack_size = *stack_size;

      // Use the kernel default limit as our size, and adjust the base to match.
      *stack_size = 8 * MB;
      *stack_base = reinterpret_cast<uint8_t*>(*stack_base) + (old_stack_size - *stack_size);

      VLOG(threads) << "Limiting unlimited stack (reported as " << PrettySize(old_stack_size) << ")"
                    << " to " << PrettySize(*stack_size)
                    << " with base " << *stack_base;
    }
  }
#endif

#endif
}

bool ReadFileToString(const std::string& file_name, std::string* result) {
  File file(file_name, O_RDONLY, false);
  if (!file.IsOpened()) {
    return false;
  }

  std::vector<char> buf(8 * KB);
  while (true) {
    int64_t n = TEMP_FAILURE_RETRY(read(file.Fd(), &buf[0], buf.size()));
    if (n == -1) {
      return false;
    }
    if (n == 0) {
      return true;
    }
    result->append(&buf[0], n);
  }
}

bool PrintFileToLog(const std::string& file_name, LogSeverity level) {
  File file(file_name, O_RDONLY, false);
  if (!file.IsOpened()) {
    return false;
  }

  constexpr size_t kBufSize = 256;  // Small buffer. Avoid stack overflow and stack size warnings.
  char buf[kBufSize + 1];           // +1 for terminator.
  size_t filled_to = 0;
  while (true) {
    DCHECK_LT(filled_to, kBufSize);
    int64_t n = TEMP_FAILURE_RETRY(read(file.Fd(), &buf[filled_to], kBufSize - filled_to));
    if (n <= 0) {
      // Print the rest of the buffer, if it exists.
      if (filled_to > 0) {
        buf[filled_to] = 0;
        LOG(level) << buf;
      }
      return n == 0;
    }
    // Scan for '\n'.
    size_t i = filled_to;
    bool found_newline = false;
    for (; i < filled_to + n; ++i) {
      if (buf[i] == '\n') {
        // Found a line break, that's something to print now.
        buf[i] = 0;
        LOG(level) << buf;
        // Copy the rest to the front.
        if (i + 1 < filled_to + n) {
          memmove(&buf[0], &buf[i + 1], filled_to + n - i - 1);
          filled_to = filled_to + n - i - 1;
        } else {
          filled_to = 0;
        }
        found_newline = true;
        break;
      }
    }
    if (found_newline) {
      continue;
    } else {
      filled_to += n;
      // Check if we must flush now.
      if (filled_to == kBufSize) {
        buf[kBufSize] = 0;
        LOG(level) << buf;
        filled_to = 0;
      }
    }
  }
}

std::string PrettyDescriptor(mirror::String* java_descriptor) {
  if (java_descriptor == nullptr) {
    return "null";
  }
  return PrettyDescriptor(java_descriptor->ToModifiedUtf8().c_str());
}

std::string PrettyDescriptor(mirror::Class* klass) {
  if (klass == nullptr) {
    return "null";
  }
  std::string temp;
  return PrettyDescriptor(klass->GetDescriptor(&temp));
}

std::string PrettyDescriptor(const char* descriptor) {
  // Count the number of '['s to get the dimensionality.
  const char* c = descriptor;
  size_t dim = 0;
  while (*c == '[') {
    dim++;
    c++;
  }

  // Reference or primitive?
  if (*c == 'L') {
    // "[[La/b/C;" -> "a.b.C[][]".
    c++;  // Skip the 'L'.
  } else {
    // "[[B" -> "byte[][]".
    // To make life easier, we make primitives look like unqualified
    // reference types.
    switch (*c) {
    case 'B': c = "byte;"; break;
    case 'C': c = "char;"; break;
    case 'D': c = "double;"; break;
    case 'F': c = "float;"; break;
    case 'I': c = "int;"; break;
    case 'J': c = "long;"; break;
    case 'S': c = "short;"; break;
    case 'Z': c = "boolean;"; break;
    case 'V': c = "void;"; break;  // Used when decoding return types.
    default: return descriptor;
    }
  }

  // At this point, 'c' is a string of the form "fully/qualified/Type;"
  // or "primitive;". Rewrite the type with '.' instead of '/':
  std::string result;
  const char* p = c;
  while (*p != ';') {
    char ch = *p++;
    if (ch == '/') {
      ch = '.';
    }
    result.push_back(ch);
  }
  // ...and replace the semicolon with 'dim' "[]" pairs:
  for (size_t i = 0; i < dim; ++i) {
    result += "[]";
  }
  return result;
}

std::string PrettyField(ArtField* f, bool with_type) {
  if (f == nullptr) {
    return "null";
  }
  std::string result;
  if (with_type) {
    result += PrettyDescriptor(f->GetTypeDescriptor());
    result += ' ';
  }
  std::string temp;
  result += PrettyDescriptor(f->GetDeclaringClass()->GetDescriptor(&temp));
  result += '.';
  result += f->GetName();
  return result;
}

std::string PrettyField(uint32_t field_idx, const DexFile& dex_file, bool with_type) {
  if (field_idx >= dex_file.NumFieldIds()) {
    return StringPrintf("<<invalid-field-idx-%d>>", field_idx);
  }
  const DexFile::FieldId& field_id = dex_file.GetFieldId(field_idx);
  std::string result;
  if (with_type) {
    result += dex_file.GetFieldTypeDescriptor(field_id);
    result += ' ';
  }
  result += PrettyDescriptor(dex_file.GetFieldDeclaringClassDescriptor(field_id));
  result += '.';
  result += dex_file.GetFieldName(field_id);
  return result;
}

std::string PrettyType(uint32_t type_idx, const DexFile& dex_file) {
  if (type_idx >= dex_file.NumTypeIds()) {
    return StringPrintf("<<invalid-type-idx-%d>>", type_idx);
  }
  const DexFile::TypeId& type_id = dex_file.GetTypeId(type_idx);
  return PrettyDescriptor(dex_file.GetTypeDescriptor(type_id));
}

std::string PrettyArguments(const char* signature) {
  std::string result;
  result += '(';
  CHECK_EQ(*signature, '(');
  ++signature;  // Skip the '('.
  while (*signature != ')') {
    size_t argument_length = 0;
    while (signature[argument_length] == '[') {
      ++argument_length;
    }
    if (signature[argument_length] == 'L') {
      argument_length = (strchr(signature, ';') - signature + 1);
    } else {
      ++argument_length;
    }
    {
      std::string argument_descriptor(signature, argument_length);
      result += PrettyDescriptor(argument_descriptor.c_str());
    }
    if (signature[argument_length] != ')') {
      result += ", ";
    }
    signature += argument_length;
  }
  CHECK_EQ(*signature, ')');
  ++signature;  // Skip the ')'.
  result += ')';
  return result;
}

std::string PrettyReturnType(const char* signature) {
  const char* return_type = strchr(signature, ')');
  CHECK(return_type != nullptr);
  ++return_type;  // Skip ')'.
  return PrettyDescriptor(return_type);
}

std::string PrettyMethod(ArtMethod* m, bool with_signature) {
  if (m == nullptr) {
    return "null";
  }
  if (!m->IsRuntimeMethod()) {
    m = m->GetInterfaceMethodIfProxy(Runtime::Current()->GetClassLinker()->GetImagePointerSize());
  }
  std::string result(PrettyDescriptor(m->GetDeclaringClassDescriptor()));
  result += '.';
  result += m->GetName();
  if (UNLIKELY(m->IsFastNative())) {
    result += "!";
  }
  if (with_signature) {
    const Signature signature = m->GetSignature();
    std::string sig_as_string(signature.ToString());
    if (signature == Signature::NoSignature()) {
      return result + sig_as_string;
    }
    result = PrettyReturnType(sig_as_string.c_str()) + " " + result +
        PrettyArguments(sig_as_string.c_str());
  }
  return result;
}

std::string PrettyMethod(uint32_t method_idx, const DexFile& dex_file, bool with_signature) {
  if (method_idx >= dex_file.NumMethodIds()) {
    return StringPrintf("<<invalid-method-idx-%d>>", method_idx);
  }
  const DexFile::MethodId& method_id = dex_file.GetMethodId(method_idx);
  std::string result(PrettyDescriptor(dex_file.GetMethodDeclaringClassDescriptor(method_id)));
  result += '.';
  result += dex_file.GetMethodName(method_id);
  if (with_signature) {
    const Signature signature = dex_file.GetMethodSignature(method_id);
    std::string sig_as_string(signature.ToString());
    if (signature == Signature::NoSignature()) {
      return result + sig_as_string;
    }
    result = PrettyReturnType(sig_as_string.c_str()) + " " + result +
        PrettyArguments(sig_as_string.c_str());
  }
  return result;
}

std::string PrettyTypeOf(mirror::Object* obj) {
  if (obj == nullptr) {
    return "null";
  }
  if (obj->GetClass() == nullptr) {
    return "(raw)";
  }
  std::string temp;
  std::string result(PrettyDescriptor(obj->GetClass()->GetDescriptor(&temp)));
  if (obj->IsClass()) {
    result += "<" + PrettyDescriptor(obj->AsClass()->GetDescriptor(&temp)) + ">";
  }
  return result;
}

std::string PrettyClass(mirror::Class* c) {
  if (c == nullptr) {
    return "null";
  }
  std::string result;
  result += "java.lang.Class<";
  result += PrettyDescriptor(c);
  result += ">";
  return result;
}

std::string PrettyClassAndClassLoader(mirror::Class* c) {
  if (c == nullptr) {
    return "null";
  }
  std::string result;
  result += "java.lang.Class<";
  result += PrettyDescriptor(c);
  result += ",";
  result += PrettyTypeOf(c->GetClassLoader());
  // TODO: add an identifying hash value for the loader
  result += ">";
  return result;
}

std::string PrettyJavaAccessFlags(uint32_t access_flags) {
  std::string result;
  if ((access_flags & kAccPublic) != 0) {
    result += "public ";
  }
  if ((access_flags & kAccProtected) != 0) {
    result += "protected ";
  }
  if ((access_flags & kAccPrivate) != 0) {
    result += "private ";
  }
  if ((access_flags & kAccFinal) != 0) {
    result += "final ";
  }
  if ((access_flags & kAccStatic) != 0) {
    result += "static ";
  }
  if ((access_flags & kAccAbstract) != 0) {
    result += "abstract ";
  }
  if ((access_flags & kAccInterface) != 0) {
    result += "interface ";
  }
  if ((access_flags & kAccTransient) != 0) {
    result += "transient ";
  }
  if ((access_flags & kAccVolatile) != 0) {
    result += "volatile ";
  }
  if ((access_flags & kAccSynchronized) != 0) {
    result += "synchronized ";
  }
  return result;
}

std::string PrettySize(int64_t byte_count) {
  // The byte thresholds at which we display amounts.  A byte count is displayed
  // in unit U when kUnitThresholds[U] <= bytes < kUnitThresholds[U+1].
  static const int64_t kUnitThresholds[] = {
    0,              // B up to...
    3*1024,         // KB up to...
    2*1024*1024,    // MB up to...
    1024*1024*1024  // GB from here.
  };
  static const int64_t kBytesPerUnit[] = { 1, KB, MB, GB };
  static const char* const kUnitStrings[] = { "B", "KB", "MB", "GB" };
  const char* negative_str = "";
  if (byte_count < 0) {
    negative_str = "-";
    byte_count = -byte_count;
  }
  int i = arraysize(kUnitThresholds);
  while (--i > 0) {
    if (byte_count >= kUnitThresholds[i]) {
      break;
    }
  }
  return StringPrintf("%s%" PRId64 "%s",
                      negative_str, byte_count / kBytesPerUnit[i], kUnitStrings[i]);
}

std::string PrintableChar(uint16_t ch) {
  std::string result;
  result += '\'';
  if (NeedsEscaping(ch)) {
    StringAppendF(&result, "\\u%04x", ch);
  } else {
    result += ch;
  }
  result += '\'';
  return result;
}

std::string PrintableString(const char* utf) {
  std::string result;
  result += '"';
  const char* p = utf;
  size_t char_count = CountModifiedUtf8Chars(p);
  for (size_t i = 0; i < char_count; ++i) {
    uint32_t ch = GetUtf16FromUtf8(&p);
    if (ch == '\\') {
      result += "\\\\";
    } else if (ch == '\n') {
      result += "\\n";
    } else if (ch == '\r') {
      result += "\\r";
    } else if (ch == '\t') {
      result += "\\t";
    } else {
      const uint16_t leading = GetLeadingUtf16Char(ch);

      if (NeedsEscaping(leading)) {
        StringAppendF(&result, "\\u%04x", leading);
      } else {
        result += leading;
      }

      const uint32_t trailing = GetTrailingUtf16Char(ch);
      if (trailing != 0) {
        // All high surrogates will need escaping.
        StringAppendF(&result, "\\u%04x", trailing);
      }
    }
  }
  result += '"';
  return result;
}

// See http://java.sun.com/j2se/1.5.0/docs/guide/jni/spec/design.html#wp615 for the full rules.
std::string MangleForJni(const std::string& s) {
  std::string result;
  size_t char_count = CountModifiedUtf8Chars(s.c_str());
  const char* cp = &s[0];
  for (size_t i = 0; i < char_count; ++i) {
    uint32_t ch = GetUtf16FromUtf8(&cp);
    if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9')) {
      result.push_back(ch);
    } else if (ch == '.' || ch == '/') {
      result += "_";
    } else if (ch == '_') {
      result += "_1";
    } else if (ch == ';') {
      result += "_2";
    } else if (ch == '[') {
      result += "_3";
    } else {
      const uint16_t leading = GetLeadingUtf16Char(ch);
      const uint32_t trailing = GetTrailingUtf16Char(ch);

      StringAppendF(&result, "_0%04x", leading);
      if (trailing != 0) {
        StringAppendF(&result, "_0%04x", trailing);
      }
    }
  }
  return result;
}

std::string DotToDescriptor(const char* class_name) {
  std::string descriptor(class_name);
  std::replace(descriptor.begin(), descriptor.end(), '.', '/');
  if (descriptor.length() > 0 && descriptor[0] != '[') {
    descriptor = "L" + descriptor + ";";
  }
  return descriptor;
}

std::string DescriptorToDot(const char* descriptor) {
  size_t length = strlen(descriptor);
  if (length > 1) {
    if (descriptor[0] == 'L' && descriptor[length - 1] == ';') {
      // Descriptors have the leading 'L' and trailing ';' stripped.
      std::string result(descriptor + 1, length - 2);
      std::replace(result.begin(), result.end(), '/', '.');
      return result;
    } else {
      // For arrays the 'L' and ';' remain intact.
      std::string result(descriptor);
      std::replace(result.begin(), result.end(), '/', '.');
      return result;
    }
  }
  // Do nothing for non-class/array descriptors.
  return descriptor;
}

std::string DescriptorToName(const char* descriptor) {
  size_t length = strlen(descriptor);
  if (descriptor[0] == 'L' && descriptor[length - 1] == ';') {
    std::string result(descriptor + 1, length - 2);
    return result;
  }
  return descriptor;
}

std::string JniShortName(ArtMethod* m) {
  std::string class_name(m->GetDeclaringClassDescriptor());
  // Remove the leading 'L' and trailing ';'...
  CHECK_EQ(class_name[0], 'L') << class_name;
  CHECK_EQ(class_name[class_name.size() - 1], ';') << class_name;
  class_name.erase(0, 1);
  class_name.erase(class_name.size() - 1, 1);

  std::string method_name(m->GetName());

  std::string short_name;
  short_name += "Java_";
  short_name += MangleForJni(class_name);
  short_name += "_";
  short_name += MangleForJni(method_name);
  return short_name;
}

std::string JniLongName(ArtMethod* m) {
  std::string long_name;
  long_name += JniShortName(m);
  long_name += "__";

  std::string signature(m->GetSignature().ToString());
  signature.erase(0, 1);
  signature.erase(signature.begin() + signature.find(')'), signature.end());

  long_name += MangleForJni(signature);

  return long_name;
}

// Helper for IsValidPartOfMemberNameUtf8(), a bit vector indicating valid low ascii.
uint32_t DEX_MEMBER_VALID_LOW_ASCII[4] = {
  0x00000000,  // 00..1f low control characters; nothing valid
  0x03ff2010,  // 20..3f digits and symbols; valid: '0'..'9', '$', '-'
  0x87fffffe,  // 40..5f uppercase etc.; valid: 'A'..'Z', '_'
  0x07fffffe   // 60..7f lowercase etc.; valid: 'a'..'z'
};

// Helper for IsValidPartOfMemberNameUtf8(); do not call directly.
bool IsValidPartOfMemberNameUtf8Slow(const char** pUtf8Ptr) {
  /*
   * It's a multibyte encoded character. Decode it and analyze. We
   * accept anything that isn't (a) an improperly encoded low value,
   * (b) an improper surrogate pair, (c) an encoded '\0', (d) a high
   * control character, or (e) a high space, layout, or special
   * character (U+00a0, U+2000..U+200f, U+2028..U+202f,
   * U+fff0..U+ffff). This is all specified in the dex format
   * document.
   */

  const uint32_t pair = GetUtf16FromUtf8(pUtf8Ptr);
  const uint16_t leading = GetLeadingUtf16Char(pair);

  // We have a surrogate pair resulting from a valid 4 byte UTF sequence.
  // No further checks are necessary because 4 byte sequences span code
  // points [U+10000, U+1FFFFF], which are valid codepoints in a dex
  // identifier. Furthermore, GetUtf16FromUtf8 guarantees that each of
  // the surrogate halves are valid and well formed in this instance.
  if (GetTrailingUtf16Char(pair) != 0) {
    return true;
  }


  // We've encountered a one, two or three byte UTF-8 sequence. The
  // three byte UTF-8 sequence could be one half of a surrogate pair.
  switch (leading >> 8) {
    case 0x00:
      // It's only valid if it's above the ISO-8859-1 high space (0xa0).
      return (leading > 0x00a0);
    case 0xd8:
    case 0xd9:
    case 0xda:
    case 0xdb:
      {
        // We found a three byte sequence encoding one half of a surrogate.
        // Look for the other half.
        const uint32_t pair2 = GetUtf16FromUtf8(pUtf8Ptr);
        const uint16_t trailing = GetLeadingUtf16Char(pair2);

        return (GetTrailingUtf16Char(pair2) == 0) && (0xdc00 <= trailing && trailing <= 0xdfff);
      }
    case 0xdc:
    case 0xdd:
    case 0xde:
    case 0xdf:
      // It's a trailing surrogate, which is not valid at this point.
      return false;
    case 0x20:
    case 0xff:
      // It's in the range that has spaces, controls, and specials.
      switch (leading & 0xfff8) {
        case 0x2000:
        case 0x2008:
        case 0x2028:
        case 0xfff0:
        case 0xfff8:
          return false;
      }
      return true;
    default:
      return true;
  }

  UNREACHABLE();
}

/* Return whether the pointed-at modified-UTF-8 encoded character is
 * valid as part of a member name, updating the pointer to point past
 * the consumed character. This will consume two encoded UTF-16 code
 * points if the character is encoded as a surrogate pair. Also, if
 * this function returns false, then the given pointer may only have
 * been partially advanced.
 */
static bool IsValidPartOfMemberNameUtf8(const char** pUtf8Ptr) {
  uint8_t c = (uint8_t) **pUtf8Ptr;
  if (LIKELY(c <= 0x7f)) {
    // It's low-ascii, so check the table.
    uint32_t wordIdx = c >> 5;
    uint32_t bitIdx = c & 0x1f;
    (*pUtf8Ptr)++;
    return (DEX_MEMBER_VALID_LOW_ASCII[wordIdx] & (1 << bitIdx)) != 0;
  }

  // It's a multibyte encoded character. Call a non-inline function
  // for the heavy lifting.
  return IsValidPartOfMemberNameUtf8Slow(pUtf8Ptr);
}

bool IsValidMemberName(const char* s) {
  bool angle_name = false;

  switch (*s) {
    case '\0':
      // The empty string is not a valid name.
      return false;
    case '<':
      angle_name = true;
      s++;
      break;
  }

  while (true) {
    switch (*s) {
      case '\0':
        return !angle_name;
      case '>':
        return angle_name && s[1] == '\0';
    }

    if (!IsValidPartOfMemberNameUtf8(&s)) {
      return false;
    }
  }
}

enum ClassNameType { kName, kDescriptor };
template<ClassNameType kType, char kSeparator>
static bool IsValidClassName(const char* s) {
  int arrayCount = 0;
  while (*s == '[') {
    arrayCount++;
    s++;
  }

  if (arrayCount > 255) {
    // Arrays may have no more than 255 dimensions.
    return false;
  }

  ClassNameType type = kType;
  if (type != kDescriptor && arrayCount != 0) {
    /*
     * If we're looking at an array of some sort, then it doesn't
     * matter if what is being asked for is a class name; the
     * format looks the same as a type descriptor in that case, so
     * treat it as such.
     */
    type = kDescriptor;
  }

  if (type == kDescriptor) {
    /*
     * We are looking for a descriptor. Either validate it as a
     * single-character primitive type, or continue on to check the
     * embedded class name (bracketed by "L" and ";").
     */
    switch (*(s++)) {
    case 'B':
    case 'C':
    case 'D':
    case 'F':
    case 'I':
    case 'J':
    case 'S':
    case 'Z':
      // These are all single-character descriptors for primitive types.
      return (*s == '\0');
    case 'V':
      // Non-array void is valid, but you can't have an array of void.
      return (arrayCount == 0) && (*s == '\0');
    case 'L':
      // Class name: Break out and continue below.
      break;
    default:
      // Oddball descriptor character.
      return false;
    }
  }

  /*
   * We just consumed the 'L' that introduces a class name as part
   * of a type descriptor, or we are looking for an unadorned class
   * name.
   */

  bool sepOrFirst = true;  // first character or just encountered a separator.
  for (;;) {
    uint8_t c = (uint8_t) *s;
    switch (c) {
    case '\0':
      /*
       * Premature end for a type descriptor, but valid for
       * a class name as long as we haven't encountered an
       * empty component (including the degenerate case of
       * the empty string "").
       */
      return (type == kName) && !sepOrFirst;
    case ';':
      /*
       * Invalid character for a class name, but the
       * legitimate end of a type descriptor. In the latter
       * case, make sure that this is the end of the string
       * and that it doesn't end with an empty component
       * (including the degenerate case of "L;").
       */
      return (type == kDescriptor) && !sepOrFirst && (s[1] == '\0');
    case '/':
    case '.':
      if (c != kSeparator) {
        // The wrong separator character.
        return false;
      }
      if (sepOrFirst) {
        // Separator at start or two separators in a row.
        return false;
      }
      sepOrFirst = true;
      s++;
      break;
    default:
      if (!IsValidPartOfMemberNameUtf8(&s)) {
        return false;
      }
      sepOrFirst = false;
      break;
    }
  }
}

bool IsValidBinaryClassName(const char* s) {
  return IsValidClassName<kName, '.'>(s);
}

bool IsValidJniClassName(const char* s) {
  return IsValidClassName<kName, '/'>(s);
}

bool IsValidDescriptor(const char* s) {
  return IsValidClassName<kDescriptor, '/'>(s);
}

void Split(const std::string& s, char separator, std::vector<std::string>* result) {
  const char* p = s.data();
  const char* end = p + s.size();
  while (p != end) {
    if (*p == separator) {
      ++p;
    } else {
      const char* start = p;
      while (++p != end && *p != separator) {
        // Skip to the next occurrence of the separator.
      }
      result->push_back(std::string(start, p - start));
    }
  }
}

std::string Trim(const std::string& s) {
  std::string result;
  unsigned int start_index = 0;
  unsigned int end_index = s.size() - 1;

  // Skip initial whitespace.
  while (start_index < s.size()) {
    if (!isspace(s[start_index])) {
      break;
    }
    start_index++;
  }

  // Skip terminating whitespace.
  while (end_index >= start_index) {
    if (!isspace(s[end_index])) {
      break;
    }
    end_index--;
  }

  // All spaces, no beef.
  if (end_index < start_index) {
    return "";
  }
  // Start_index is the first non-space, end_index is the last one.
  return s.substr(start_index, end_index - start_index + 1);
}

template <typename StringT>
std::string Join(const std::vector<StringT>& strings, char separator) {
  if (strings.empty()) {
    return "";
  }

  std::string result(strings[0]);
  for (size_t i = 1; i < strings.size(); ++i) {
    result += separator;
    result += strings[i];
  }
  return result;
}

// Explicit instantiations.
template std::string Join<std::string>(const std::vector<std::string>& strings, char separator);
template std::string Join<const char*>(const std::vector<const char*>& strings, char separator);

bool StartsWith(const std::string& s, const char* prefix) {
  return s.compare(0, strlen(prefix), prefix) == 0;
}

bool EndsWith(const std::string& s, const char* suffix) {
  size_t suffix_length = strlen(suffix);
  size_t string_length = s.size();
  if (suffix_length > string_length) {
    return false;
  }
  size_t offset = string_length - suffix_length;
  return s.compare(offset, suffix_length, suffix) == 0;
}

void SetThreadName(const char* thread_name) {
  int hasAt = 0;
  int hasDot = 0;
  const char* s = thread_name;
  while (*s) {
    if (*s == '.') {
      hasDot = 1;
    } else if (*s == '@') {
      hasAt = 1;
    }
    s++;
  }
  int len = s - thread_name;
  if (len < 15 || hasAt || !hasDot) {
    s = thread_name;
  } else {
    s = thread_name + len - 15;
  }
#if defined(__linux__)
  // pthread_setname_np fails rather than truncating long strings.
  char buf[16];       // MAX_TASK_COMM_LEN=16 is hard-coded in the kernel.
  strncpy(buf, s, sizeof(buf)-1);
  buf[sizeof(buf)-1] = '\0';
  errno = pthread_setname_np(pthread_self(), buf);
  if (errno != 0) {
    PLOG(WARNING) << "Unable to set the name of current thread to '" << buf << "'";
  }
#else  // __APPLE__
  pthread_setname_np(thread_name);
#endif
}

void GetTaskStats(pid_t tid, char* state, int* utime, int* stime, int* task_cpu) {
  *utime = *stime = *task_cpu = 0;
  std::string stats;
  if (!ReadFileToString(StringPrintf("/proc/self/task/%d/stat", tid), &stats)) {
    return;
  }
  // Skip the command, which may contain spaces.
  stats = stats.substr(stats.find(')') + 2);
  // Extract the three fields we care about.
  std::vector<std::string> fields;
  Split(stats, ' ', &fields);
  *state = fields[0][0];
  *utime = strtoull(fields[11].c_str(), nullptr, 10);
  *stime = strtoull(fields[12].c_str(), nullptr, 10);
  *task_cpu = strtoull(fields[36].c_str(), nullptr, 10);
}

std::string GetSchedulerGroupName(pid_t tid) {
  // /proc/<pid>/cgroup looks like this:
  // 2:devices:/
  // 1:cpuacct,cpu:/
  // We want the third field from the line whose second field contains the "cpu" token.
  std::string cgroup_file;
  if (!ReadFileToString(StringPrintf("/proc/self/task/%d/cgroup", tid), &cgroup_file)) {
    return "";
  }
  std::vector<std::string> cgroup_lines;
  Split(cgroup_file, '\n', &cgroup_lines);
  for (size_t i = 0; i < cgroup_lines.size(); ++i) {
    std::vector<std::string> cgroup_fields;
    Split(cgroup_lines[i], ':', &cgroup_fields);
    std::vector<std::string> cgroups;
    Split(cgroup_fields[1], ',', &cgroups);
    for (size_t j = 0; j < cgroups.size(); ++j) {
      if (cgroups[j] == "cpu") {
        return cgroup_fields[2].substr(1);  // Skip the leading slash.
      }
    }
  }
  return "";
}

const char* GetAndroidRoot() {
  const char* android_root = getenv("ANDROID_ROOT");
  if (android_root == nullptr) {
    if (OS::DirectoryExists("/system")) {
      android_root = "/system";
    } else {
      LOG(FATAL) << "ANDROID_ROOT not set and /system does not exist";
      return "";
    }
  }
  if (!OS::DirectoryExists(android_root)) {
    LOG(FATAL) << "Failed to find ANDROID_ROOT directory " << android_root;
    return "";
  }
  return android_root;
}

const char* GetAndroidData() {
  std::string error_msg;
  const char* dir = GetAndroidDataSafe(&error_msg);
  if (dir != nullptr) {
    return dir;
  } else {
    LOG(FATAL) << error_msg;
    return "";
  }
}

const char* GetAndroidDataSafe(std::string* error_msg) {
  const char* android_data = getenv("ANDROID_DATA");
  if (android_data == nullptr) {
    if (OS::DirectoryExists("/data")) {
      android_data = "/data";
    } else {
      *error_msg = "ANDROID_DATA not set and /data does not exist";
      return nullptr;
    }
  }
  if (!OS::DirectoryExists(android_data)) {
    *error_msg = StringPrintf("Failed to find ANDROID_DATA directory %s", android_data);
    return nullptr;
  }
  return android_data;
}

void GetDalvikCache(const char* subdir, const bool create_if_absent, std::string* dalvik_cache,
                    bool* have_android_data, bool* dalvik_cache_exists, bool* is_global_cache) {
  CHECK(subdir != nullptr);
  std::string error_msg;
  const char* android_data = GetAndroidDataSafe(&error_msg);
  if (android_data == nullptr) {
    *have_android_data = false;
    *dalvik_cache_exists = false;
    *is_global_cache = false;
    return;
  } else {
    *have_android_data = true;
  }
  const std::string dalvik_cache_root(StringPrintf("%s/dalvik-cache/", android_data));
  *dalvik_cache = dalvik_cache_root + subdir;
  *dalvik_cache_exists = OS::DirectoryExists(dalvik_cache->c_str());
  *is_global_cache = strcmp(android_data, "/data") == 0;
  if (create_if_absent && !*dalvik_cache_exists && !*is_global_cache) {
    // Don't create the system's /data/dalvik-cache/... because it needs special permissions.
    *dalvik_cache_exists = ((mkdir(dalvik_cache_root.c_str(), 0700) == 0 || errno == EEXIST) &&
                            (mkdir(dalvik_cache->c_str(), 0700) == 0 || errno == EEXIST));
  }
}

std::string GetDalvikCache(const char* subdir) {
  CHECK(subdir != nullptr);
  const char* android_data = GetAndroidData();
  const std::string dalvik_cache_root(StringPrintf("%s/dalvik-cache/", android_data));
  const std::string dalvik_cache = dalvik_cache_root + subdir;
  if (!OS::DirectoryExists(dalvik_cache.c_str())) {
    // TODO: Check callers. Traditional behavior is to not abort.
    return "";
  }
  return dalvik_cache;
}

bool GetDalvikCacheFilename(const char* location, const char* cache_location,
                            std::string* filename, std::string* error_msg) {
  if (location[0] != '/') {
    *error_msg = StringPrintf("Expected path in location to be absolute: %s", location);
    return false;
  }
  std::string cache_file(&location[1]);  // skip leading slash
  if (!EndsWith(location, ".dex") && !EndsWith(location, ".art") && !EndsWith(location, ".oat")) {
    cache_file += "/";
    cache_file += DexFile::kClassesDex;
  }
  std::replace(cache_file.begin(), cache_file.end(), '/', '@');
  *filename = StringPrintf("%s/%s", cache_location, cache_file.c_str());
  return true;
}

static void InsertIsaDirectory(const InstructionSet isa, std::string* filename) {
  // in = /foo/bar/baz
  // out = /foo/bar/<isa>/baz
  size_t pos = filename->rfind('/');
  CHECK_NE(pos, std::string::npos) << *filename << " " << isa;
  filename->insert(pos, "/", 1);
  filename->insert(pos + 1, GetInstructionSetString(isa));
}

std::string GetSystemImageFilename(const char* location, const InstructionSet isa) {
  // location = /system/framework/boot.art
  // filename = /system/framework/<isa>/boot.art
  std::string filename(location);
  InsertIsaDirectory(isa, &filename);
  return filename;
}

int ExecAndReturnCode(std::vector<std::string>& arg_vector, std::string* error_msg) {
  const std::string command_line(Join(arg_vector, ' '));
  CHECK_GE(arg_vector.size(), 1U) << command_line;

  // Convert the args to char pointers.
  const char* program = arg_vector[0].c_str();
  std::vector<char*> args;
  for (size_t i = 0; i < arg_vector.size(); ++i) {
    const std::string& arg = arg_vector[i];
    char* arg_str = const_cast<char*>(arg.c_str());
    CHECK(arg_str != nullptr) << i;
    args.push_back(arg_str);
  }
  args.push_back(nullptr);

  // fork and exec
  pid_t pid = fork();
  if (pid == 0) {
    // no allocation allowed between fork and exec

    // change process groups, so we don't get reaped by ProcessManager
    setpgid(0, 0);

    // (b/30160149): protect subprocesses from modifications to LD_LIBRARY_PATH, etc.
    // Use the snapshot of the environment from the time the runtime was created.
    char** envp = (Runtime::Current() == nullptr) ? nullptr : Runtime::Current()->GetEnvSnapshot();
    if (envp == nullptr) {
      execv(program, &args[0]);
    } else {
      execve(program, &args[0], envp);
    }
    PLOG(ERROR) << "Failed to execve(" << command_line << ")";
    // _exit to avoid atexit handlers in child.
    _exit(1);
  } else {
    if (pid == -1) {
      *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
                                command_line.c_str(), strerror(errno));
      return -1;
    }

    // wait for subprocess to finish
    int status = -1;
    pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
    if (got_pid != pid) {
      *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
                                "wanted %d, got %d: %s",
                                command_line.c_str(), pid, got_pid, strerror(errno));
      return -1;
    }
    if (WIFEXITED(status)) {
      return WEXITSTATUS(status);
    }
    return -1;
  }
}

bool Exec(std::vector<std::string>& arg_vector, std::string* error_msg) {
  int status = ExecAndReturnCode(arg_vector, error_msg);
  if (status != 0) {
    const std::string command_line(Join(arg_vector, ' '));
    *error_msg = StringPrintf("Failed execv(%s) because non-0 exit status",
                              command_line.c_str());
    return false;
  }
  return true;
}

bool FileExists(const std::string& filename) {
  struct stat buffer;
  return stat(filename.c_str(), &buffer) == 0;
}

bool FileExistsAndNotEmpty(const std::string& filename) {
  struct stat buffer;
  if (stat(filename.c_str(), &buffer) != 0) {
    return false;
  }
  return buffer.st_size > 0;
}

std::string ReplaceFileExtension(const std::string& filename, const std::string& new_extension) {
  const size_t last_ext = filename.find_last_of('.');
  if (last_ext == std::string::npos) {
    return filename + "." + new_extension;
  } else {
    return filename.substr(0, last_ext + 1) + new_extension;
  }
}

std::string PrettyDescriptor(Primitive::Type type) {
  return PrettyDescriptor(Primitive::Descriptor(type));
}

static void DumpMethodCFGImpl(const DexFile* dex_file,
                              uint32_t dex_method_idx,
                              const DexFile::CodeItem* code_item,
                              std::ostream& os) {
  os << "digraph {\n";
  os << "  # /* " << PrettyMethod(dex_method_idx, *dex_file, true) << " */\n";

  std::set<uint32_t> dex_pc_is_branch_target;
  {
    // Go and populate.
    const Instruction* inst = Instruction::At(code_item->insns_);
    for (uint32_t dex_pc = 0;
         dex_pc < code_item->insns_size_in_code_units_;
         dex_pc += inst->SizeInCodeUnits(), inst = inst->Next()) {
      if (inst->IsBranch()) {
        dex_pc_is_branch_target.insert(dex_pc + inst->GetTargetOffset());
      } else if (inst->IsSwitch()) {
        const uint16_t* insns = code_item->insns_ + dex_pc;
        int32_t switch_offset = insns[1] | (static_cast<int32_t>(insns[2]) << 16);
        const uint16_t* switch_insns = insns + switch_offset;
        uint32_t switch_count = switch_insns[1];
        int32_t targets_offset;
        if ((*insns & 0xff) == Instruction::PACKED_SWITCH) {
          /* 0=sig, 1=count, 2/3=firstKey */
          targets_offset = 4;
        } else {
          /* 0=sig, 1=count, 2..count*2 = keys */
          targets_offset = 2 + 2 * switch_count;
        }
        for (uint32_t targ = 0; targ < switch_count; targ++) {
          int32_t offset =
              static_cast<int32_t>(switch_insns[targets_offset + targ * 2]) |
              static_cast<int32_t>(switch_insns[targets_offset + targ * 2 + 1] << 16);
          dex_pc_is_branch_target.insert(dex_pc + offset);
        }
      }
    }
  }

  // Create nodes for "basic blocks."
  std::map<uint32_t, uint32_t> dex_pc_to_node_id;  // This only has entries for block starts.
  std::map<uint32_t, uint32_t> dex_pc_to_incl_id;  // This has entries for all dex pcs.

  {
    const Instruction* inst = Instruction::At(code_item->insns_);
    bool first_in_block = true;
    bool force_new_block = false;
    for (uint32_t dex_pc = 0;
         dex_pc < code_item->insns_size_in_code_units_;
         dex_pc += inst->SizeInCodeUnits(), inst = inst->Next()) {
      if (dex_pc == 0 ||
          (dex_pc_is_branch_target.find(dex_pc) != dex_pc_is_branch_target.end()) ||
          force_new_block) {
        uint32_t id = dex_pc_to_node_id.size();
        if (id > 0) {
          // End last node.
          os << "}\"];\n";
        }
        // Start next node.
        os << "  node" << id << " [shape=record,label=\"{";
        dex_pc_to_node_id.insert(std::make_pair(dex_pc, id));
        first_in_block = true;
        force_new_block = false;
      }

      // Register instruction.
      dex_pc_to_incl_id.insert(std::make_pair(dex_pc, dex_pc_to_node_id.size() - 1));

      // Print instruction.
      if (!first_in_block) {
        os << " | ";
      } else {
        first_in_block = false;
      }

      // Dump the instruction. Need to escape '"', '<', '>', '{' and '}'.
      os << "<" << "p" << dex_pc << ">";
      os << " 0x" << std::hex << dex_pc << std::dec << ": ";
      std::string inst_str = inst->DumpString(dex_file);
      size_t cur_start = 0;  // It's OK to start at zero, instruction dumps don't start with chars
                             // we need to escape.
      while (cur_start != std::string::npos) {
        size_t next_escape = inst_str.find_first_of("\"{}<>", cur_start + 1);
        if (next_escape == std::string::npos) {
          os << inst_str.substr(cur_start, inst_str.size() - cur_start);
          break;
        } else {
          os << inst_str.substr(cur_start, next_escape - cur_start);
          // Escape all necessary characters.
          while (next_escape < inst_str.size()) {
            char c = inst_str.at(next_escape);
            if (c == '"' || c == '{' || c == '}' || c == '<' || c == '>') {
              os << '\\' << c;
            } else {
              break;
            }
            next_escape++;
          }
          if (next_escape >= inst_str.size()) {
            next_escape = std::string::npos;
          }
          cur_start = next_escape;
        }
      }

      // Force a new block for some fall-throughs and some instructions that terminate the "local"
      // control flow.
      force_new_block = inst->IsSwitch() || inst->IsBasicBlockEnd();
    }
    // Close last node.
    if (dex_pc_to_node_id.size() > 0) {
      os << "}\"];\n";
    }
  }

  // Create edges between them.
  {
    std::ostringstream regular_edges;
    std::ostringstream taken_edges;
    std::ostringstream exception_edges;

    // Common set of exception edges.
    std::set<uint32_t> exception_targets;

    // These blocks (given by the first dex pc) need exception per dex-pc handling in a second
    // pass. In the first pass we try and see whether we can use a common set of edges.
    std::set<uint32_t> blocks_with_detailed_exceptions;

    {
      uint32_t last_node_id = std::numeric_limits<uint32_t>::max();
      uint32_t old_dex_pc = 0;
      uint32_t block_start_dex_pc = std::numeric_limits<uint32_t>::max();
      const Instruction* inst = Instruction::At(code_item->insns_);
      for (uint32_t dex_pc = 0;
          dex_pc < code_item->insns_size_in_code_units_;
          old_dex_pc = dex_pc, dex_pc += inst->SizeInCodeUnits(), inst = inst->Next()) {
        {
          auto it = dex_pc_to_node_id.find(dex_pc);
          if (it != dex_pc_to_node_id.end()) {
            if (!exception_targets.empty()) {
              // It seems the last block had common exception handlers. Add the exception edges now.
              uint32_t node_id = dex_pc_to_node_id.find(block_start_dex_pc)->second;
              for (uint32_t handler_pc : exception_targets) {
                auto node_id_it = dex_pc_to_incl_id.find(handler_pc);
                if (node_id_it != dex_pc_to_incl_id.end()) {
                  exception_edges << "  node" << node_id
                      << " -> node" << node_id_it->second << ":p" << handler_pc
                      << ";\n";
                }
              }
              exception_targets.clear();
            }

            block_start_dex_pc = dex_pc;

            // Seems to be a fall-through, connect to last_node_id. May be spurious edges for things
            // like switch data.
            uint32_t old_last = last_node_id;
            last_node_id = it->second;
            if (old_last != std::numeric_limits<uint32_t>::max()) {
              regular_edges << "  node" << old_last << ":p" << old_dex_pc
                  << " -> node" << last_node_id << ":p" << dex_pc
                  << ";\n";
            }
          }

          // Look at the exceptions of the first entry.
          CatchHandlerIterator catch_it(*code_item, dex_pc);
          for (; catch_it.HasNext(); catch_it.Next()) {
            exception_targets.insert(catch_it.GetHandlerAddress());
          }
        }

        // Handle instruction.

        // Branch: something with at most two targets.
        if (inst->IsBranch()) {
          const int32_t offset = inst->GetTargetOffset();
          const bool conditional = !inst->IsUnconditional();

          auto target_it = dex_pc_to_node_id.find(dex_pc + offset);
          if (target_it != dex_pc_to_node_id.end()) {
            taken_edges << "  node" << last_node_id << ":p" << dex_pc
                << " -> node" << target_it->second << ":p" << (dex_pc + offset)
                << ";\n";
          }
          if (!conditional) {
            // No fall-through.
            last_node_id = std::numeric_limits<uint32_t>::max();
          }
        } else if (inst->IsSwitch()) {
          // TODO: Iterate through all switch targets.
          const uint16_t* insns = code_item->insns_ + dex_pc;
          /* make sure the start of the switch is in range */
          int32_t switch_offset = insns[1] | (static_cast<int32_t>(insns[2]) << 16);
          /* offset to switch table is a relative branch-style offset */
          const uint16_t* switch_insns = insns + switch_offset;
          uint32_t switch_count = switch_insns[1];
          int32_t targets_offset;
          if ((*insns & 0xff) == Instruction::PACKED_SWITCH) {
            /* 0=sig, 1=count, 2/3=firstKey */
            targets_offset = 4;
          } else {
            /* 0=sig, 1=count, 2..count*2 = keys */
            targets_offset = 2 + 2 * switch_count;
          }
          /* make sure the end of the switch is in range */
          /* verify each switch target */
          for (uint32_t targ = 0; targ < switch_count; targ++) {
            int32_t offset =
                static_cast<int32_t>(switch_insns[targets_offset + targ * 2]) |
                static_cast<int32_t>(switch_insns[targets_offset + targ * 2 + 1] << 16);
            int32_t abs_offset = dex_pc + offset;
            auto target_it = dex_pc_to_node_id.find(abs_offset);
            if (target_it != dex_pc_to_node_id.end()) {
              // TODO: value label.
              taken_edges << "  node" << last_node_id << ":p" << dex_pc
                  << " -> node" << target_it->second << ":p" << (abs_offset)
                  << ";\n";
            }
          }
        }

        // Exception edges. If this is not the first instruction in the block
        if (block_start_dex_pc != dex_pc) {
          std::set<uint32_t> current_handler_pcs;
          CatchHandlerIterator catch_it(*code_item, dex_pc);
          for (; catch_it.HasNext(); catch_it.Next()) {
            current_handler_pcs.insert(catch_it.GetHandlerAddress());
          }
          if (current_handler_pcs != exception_targets) {
            exception_targets.clear();  // Clear so we don't do something at the end.
            blocks_with_detailed_exceptions.insert(block_start_dex_pc);
          }
        }

        if (inst->IsReturn() ||
            (inst->Opcode() == Instruction::THROW) ||
            (inst->IsBranch() && inst->IsUnconditional())) {
          // No fall-through.
          last_node_id = std::numeric_limits<uint32_t>::max();
        }
      }
      // Finish up the last block, if it had common exceptions.
      if (!exception_targets.empty()) {
        // It seems the last block had common exception handlers. Add the exception edges now.
        uint32_t node_id = dex_pc_to_node_id.find(block_start_dex_pc)->second;
        for (uint32_t handler_pc : exception_targets) {
          auto node_id_it = dex_pc_to_incl_id.find(handler_pc);
          if (node_id_it != dex_pc_to_incl_id.end()) {
            exception_edges << "  node" << node_id
                << " -> node" << node_id_it->second << ":p" << handler_pc
                << ";\n";
          }
        }
        exception_targets.clear();
      }
    }

    // Second pass for detailed exception blocks.
    // TODO
    // Exception edges. If this is not the first instruction in the block
    for (uint32_t dex_pc : blocks_with_detailed_exceptions) {
      const Instruction* inst = Instruction::At(&code_item->insns_[dex_pc]);
      uint32_t this_node_id = dex_pc_to_incl_id.find(dex_pc)->second;
      while (true) {
        CatchHandlerIterator catch_it(*code_item, dex_pc);
        if (catch_it.HasNext()) {
          std::set<uint32_t> handled_targets;
          for (; catch_it.HasNext(); catch_it.Next()) {
            uint32_t handler_pc = catch_it.GetHandlerAddress();
            auto it = handled_targets.find(handler_pc);
            if (it == handled_targets.end()) {
              auto node_id_it = dex_pc_to_incl_id.find(handler_pc);
              if (node_id_it != dex_pc_to_incl_id.end()) {
                exception_edges << "  node" << this_node_id << ":p" << dex_pc
                    << " -> node" << node_id_it->second << ":p" << handler_pc
                    << ";\n";
              }

              // Mark as done.
              handled_targets.insert(handler_pc);
            }
          }
        }
        if (inst->IsBasicBlockEnd()) {
          break;
        }

        // Loop update. Have a break-out if the next instruction is a branch target and thus in
        // another block.
        dex_pc += inst->SizeInCodeUnits();
        if (dex_pc >= code_item->insns_size_in_code_units_) {
          break;
        }
        if (dex_pc_to_node_id.find(dex_pc) != dex_pc_to_node_id.end()) {
          break;
        }
        inst = inst->Next();
      }
    }

    // Write out the sub-graphs to make edges styled.
    os << "\n";
    os << "  subgraph regular_edges {\n";
    os << "    edge [color=\"#000000\",weight=.3,len=3];\n\n";
    os << "    " << regular_edges.str() << "\n";
    os << "  }\n\n";

    os << "  subgraph taken_edges {\n";
    os << "    edge [color=\"#00FF00\",weight=.3,len=3];\n\n";
    os << "    " << taken_edges.str() << "\n";
    os << "  }\n\n";

    os << "  subgraph exception_edges {\n";
    os << "    edge [color=\"#FF0000\",weight=.3,len=3];\n\n";
    os << "    " << exception_edges.str() << "\n";
    os << "  }\n\n";
  }

  os << "}\n";
}

void DumpMethodCFG(ArtMethod* method, std::ostream& os) {
  const DexFile* dex_file = method->GetDexFile();
  const DexFile::CodeItem* code_item = dex_file->GetCodeItem(method->GetCodeItemOffset());

  DumpMethodCFGImpl(dex_file, method->GetDexMethodIndex(), code_item, os);
}

void DumpMethodCFG(const DexFile* dex_file, uint32_t dex_method_idx, std::ostream& os) {
  // This is painful, we need to find the code item. That means finding the class, and then
  // iterating the table.
  if (dex_method_idx >= dex_file->NumMethodIds()) {
    os << "Could not find method-idx.";
    return;
  }
  const DexFile::MethodId& method_id = dex_file->GetMethodId(dex_method_idx);

  const DexFile::ClassDef* class_def = dex_file->FindClassDef(method_id.class_idx_);
  if (class_def == nullptr) {
    os << "Could not find class-def.";
    return;
  }

  const uint8_t* class_data = dex_file->GetClassData(*class_def);
  if (class_data == nullptr) {
    os << "No class data.";
    return;
  }

  ClassDataItemIterator it(*dex_file, class_data);
  // Skip fields
  while (it.HasNextStaticField() || it.HasNextInstanceField()) {
    it.Next();
  }

  // Find method, and dump it.
  while (it.HasNextDirectMethod() || it.HasNextVirtualMethod()) {
    uint32_t method_idx = it.GetMemberIndex();
    if (method_idx == dex_method_idx) {
      DumpMethodCFGImpl(dex_file, dex_method_idx, it.GetMethodCodeItem(), os);
      return;
    }
    it.Next();
  }

  // Otherwise complain.
  os << "Something went wrong, didn't find the method in the class data.";
}

static void ParseStringAfterChar(const std::string& s,
                                 char c,
                                 std::string* parsed_value,
                                 UsageFn Usage) {
  std::string::size_type colon = s.find(c);
  if (colon == std::string::npos) {
    Usage("Missing char %c in option %s\n", c, s.c_str());
  }
  // Add one to remove the char we were trimming until.
  *parsed_value = s.substr(colon + 1);
}

void ParseDouble(const std::string& option,
                 char after_char,
                 double min,
                 double max,
                 double* parsed_value,
                 UsageFn Usage) {
  std::string substring;
  ParseStringAfterChar(option, after_char, &substring, Usage);
  bool sane_val = true;
  double value;
  if ((false)) {
    // TODO: this doesn't seem to work on the emulator.  b/15114595
    std::stringstream iss(substring);
    iss >> value;
    // Ensure that we have a value, there was no cruft after it and it satisfies a sensible range.
    sane_val = iss.eof() && (value >= min) && (value <= max);
  } else {
    char* end = nullptr;
    value = strtod(substring.c_str(), &end);
    sane_val = *end == '\0' && value >= min && value <= max;
  }
  if (!sane_val) {
    Usage("Invalid double value %s for option %s\n", substring.c_str(), option.c_str());
  }
  *parsed_value = value;
}

int64_t GetFileSizeBytes(const std::string& filename) {
  struct stat stat_buf;
  int rc = stat(filename.c_str(), &stat_buf);
  return rc == 0 ? stat_buf.st_size : -1;
}

void SleepForever() {
  while (true) {
    usleep(1000000);
  }
}

}  // namespace art