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 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
 #ifndef GOOGLE_PROTOBUF_PARSE_CONTEXT_H__
 #define GOOGLE_PROTOBUF_PARSE_CONTEXT_H__
 
 #include <cstdint>
 #include <cstring>
 #include <string>
 #include <type_traits>
 #include <utility>
 
 #include "absl/base/config.h"
 #include "absl/log/absl_check.h"
 #include "absl/log/absl_log.h"
 #include "absl/strings/cord.h"
 #include "absl/strings/internal/resize_uninitialized.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 #include "google/protobuf/arena.h"
 #include "google/protobuf/arenastring.h"
 #include "google/protobuf/endian.h"
 #include "google/protobuf/inlined_string_field.h"
 #include "google/protobuf/io/coded_stream.h"
 #include "google/protobuf/io/zero_copy_stream.h"
 #include "google/protobuf/metadata_lite.h"
 #include "google/protobuf/port.h"
 #include "google/protobuf/repeated_field.h"
 #include "google/protobuf/wire_format_lite.h"
 
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
 
 namespace google {
 namespace protobuf {
 
 class UnknownFieldSet;
 class DescriptorPool;
 class MessageFactory;
 
 namespace internal {
 
 // Template code below needs to know about the existence of these functions.
 PROTOBUF_EXPORT void WriteVarint(uint32_t num, uint64_t val, std::string* s);
 PROTOBUF_EXPORT void WriteLengthDelimited(uint32_t num, absl::string_view val,
                                           std::string* s);
 // Inline because it is just forwarding to s->WriteVarint
 inline void WriteVarint(uint32_t num, uint64_t val, UnknownFieldSet* s);
 inline void WriteLengthDelimited(uint32_t num, absl::string_view val,
                                  UnknownFieldSet* s);
 
 
 // The basic abstraction the parser is designed for is a slight modification
 // of the ZeroCopyInputStream (ZCIS) abstraction. A ZCIS presents a serialized
 // stream as a series of buffers that concatenate to the full stream.
 // Pictorially a ZCIS presents a stream in chunks like so
 // [---------------------------------------------------------------]
 // [---------------------] chunk 1
 //                      [----------------------------] chunk 2
 //                                          chunk 3 [--------------]
 //
 // Where the '-' represent the bytes which are vertically lined up with the
 // bytes of the stream. The proto parser requires its input to be presented
 // similarly with the extra
 // property that each chunk has kSlopBytes past its end that overlaps with the
 // first kSlopBytes of the next chunk, or if there is no next chunk at least its
 // still valid to read those bytes. Again, pictorially, we now have
 //
 // [---------------------------------------------------------------]
 // [-------------------....] chunk 1
 //                    [------------------------....] chunk 2
 //                                    chunk 3 [------------------..**]
 //                                                      chunk 4 [--****]
 // Here '-' mean the bytes of the stream or chunk and '.' means bytes past the
 // chunk that match up with the start of the next chunk. Above each chunk has
 // 4 '.' after the chunk. In the case these 'overflow' bytes represents bytes
 // past the stream, indicated by '*' above, their values are unspecified. It is
 // still legal to read them (ie. should not segfault). Reading past the
 // end should be detected by the user and indicated as an error.
 //
 // The reason for this, admittedly, unconventional invariant is to ruthlessly
 // optimize the protobuf parser. Having an overlap helps in two important ways.
 // Firstly it alleviates having to performing bounds checks if a piece of code
 // is guaranteed to not read more than kSlopBytes. Secondly, and more
 // importantly, the protobuf wireformat is such that reading a key/value pair is
 // always less than 16 bytes. This removes the need to change to next buffer in
 // the middle of reading primitive values. Hence there is no need to store and
 // load the current position.
 
 class PROTOBUF_EXPORT EpsCopyInputStream {
  public:
   enum { kMaxCordBytesToCopy = 512 };
   explicit EpsCopyInputStream(bool enable_aliasing)
       : aliasing_(enable_aliasing ? kOnPatch : kNoAliasing) {}
 
   void BackUp(const char* ptr) {
     ABSL_DCHECK(ptr <= buffer_end_ + kSlopBytes);
     int count;
     if (next_chunk_ == patch_buffer_) {
       count = static_cast<int>(buffer_end_ + kSlopBytes - ptr);
     } else {
       count = size_ + static_cast<int>(buffer_end_ - ptr);
     }
     if (count > 0) StreamBackUp(count);
   }
 
   // In sanitizer mode we use memory poisoning to guarantee that:
   //  - We do not read an uninitialized token.
   //  - We would like to verify that this token was consumed, but unfortunately
   //    __asan_address_is_poisoned is allowed to have false negatives.
   class LimitToken {
    public:
     LimitToken() { PROTOBUF_POISON_MEMORY_REGION(&token_, sizeof(token_)); }
 
     explicit LimitToken(int token) : token_(token) {
       PROTOBUF_UNPOISON_MEMORY_REGION(&token_, sizeof(token_));
     }
 
     LimitToken(const LimitToken&) = delete;
     LimitToken& operator=(const LimitToken&) = delete;
 
     LimitToken(LimitToken&& other) { *this = std::move(other); }
 
     LimitToken& operator=(LimitToken&& other) {
       PROTOBUF_UNPOISON_MEMORY_REGION(&token_, sizeof(token_));
       token_ = other.token_;
       PROTOBUF_POISON_MEMORY_REGION(&other.token_, sizeof(token_));
       return *this;
     }
 
     ~LimitToken() { PROTOBUF_UNPOISON_MEMORY_REGION(&token_, sizeof(token_)); }
 
     int token() && {
       int t = token_;
       PROTOBUF_POISON_MEMORY_REGION(&token_, sizeof(token_));
       return t;
     }
 
    private:
     int token_;
   };
 
   // If return value is negative it's an error
   PROTOBUF_NODISCARD LimitToken PushLimit(const char* ptr, int limit) {
     ABSL_DCHECK(limit >= 0 && limit <= INT_MAX - kSlopBytes);
     // This add is safe due to the invariant above, because
     // ptr - buffer_end_ <= kSlopBytes.
     limit += static_cast<int>(ptr - buffer_end_);
     limit_end_ = buffer_end_ + (std::min)(0, limit);
     auto old_limit = limit_;
     limit_ = limit;
     return LimitToken(old_limit - limit);
   }
 
   PROTOBUF_NODISCARD bool PopLimit(LimitToken delta) {
     // We must update the limit first before the early return. Otherwise, we can
     // end up with an invalid limit and it can lead to integer overflows.
     limit_ = limit_ + std::move(delta).token();
     if (PROTOBUF_PREDICT_FALSE(!EndedAtLimit())) return false;
     // TODO We could remove this line and hoist the code to
     // DoneFallback. Study the perf/bin-size effects.
     limit_end_ = buffer_end_ + (std::min)(0, limit_);
     return true;
   }
 
   PROTOBUF_NODISCARD const char* Skip(const char* ptr, int size) {
     if (size <= buffer_end_ + kSlopBytes - ptr) {
       return ptr + size;
     }
     return SkipFallback(ptr, size);
   }
   PROTOBUF_NODISCARD const char* ReadString(const char* ptr, int size,
                                             std::string* s) {
     if (size <= buffer_end_ + kSlopBytes - ptr) {
       // Fundamentally we just want to do assign to the string.
       // However micro-benchmarks regress on string reading cases. So we copy
       // the same logic from the old CodedInputStream ReadString. Note: as of
       // Apr 2021, this is still a significant win over `assign()`.
       absl::strings_internal::STLStringResizeUninitialized(s, size);
       char* z = &(*s)[0];
       memcpy(z, ptr, size);
       return ptr + size;
     }
     return ReadStringFallback(ptr, size, s);
   }
   PROTOBUF_NODISCARD const char* AppendString(const char* ptr, int size,
                                               std::string* s) {
     if (size <= buffer_end_ + kSlopBytes - ptr) {
       s->append(ptr, size);
       return ptr + size;
     }
     return AppendStringFallback(ptr, size, s);
   }
   // Implemented in arenastring.cc
   PROTOBUF_NODISCARD const char* ReadArenaString(const char* ptr,
                                                  ArenaStringPtr* s,
                                                  Arena* arena);
 
   PROTOBUF_NODISCARD const char* ReadCord(const char* ptr, int size,
                                           ::absl::Cord* cord) {
     if (size <= std::min<int>(static_cast<int>(buffer_end_ + kSlopBytes - ptr),
                               kMaxCordBytesToCopy)) {
       *cord = absl::string_view(ptr, size);
       return ptr + size;
     }
     return ReadCordFallback(ptr, size, cord);
   }
 
 
   template <typename Tag, typename T>
   PROTOBUF_NODISCARD const char* ReadRepeatedFixed(const char* ptr,
                                                    Tag expected_tag,
                                                    RepeatedField<T>* out);
 
   template <typename T>
   PROTOBUF_NODISCARD const char* ReadPackedFixed(const char* ptr, int size,
                                                  RepeatedField<T>* out);
   template <typename Add>
   PROTOBUF_NODISCARD const char* ReadPackedVarint(const char* ptr, Add add) {
     return ReadPackedVarint(ptr, add, [](int) {});
   }
   template <typename Add, typename SizeCb>
   PROTOBUF_NODISCARD const char* ReadPackedVarint(const char* ptr, Add add,
                                                   SizeCb size_callback);
 
   uint32_t LastTag() const { return last_tag_minus_1_ + 1; }
   bool ConsumeEndGroup(uint32_t start_tag) {
     bool res = last_tag_minus_1_ == start_tag;
     last_tag_minus_1_ = 0;
     return res;
   }
   bool EndedAtLimit() const { return last_tag_minus_1_ == 0; }
   bool EndedAtEndOfStream() const { return last_tag_minus_1_ == 1; }
   void SetLastTag(uint32_t tag) { last_tag_minus_1_ = tag - 1; }
   void SetEndOfStream() { last_tag_minus_1_ = 1; }
   bool IsExceedingLimit(const char* ptr) {
     return ptr > limit_end_ &&
            (next_chunk_ == nullptr || ptr - buffer_end_ > limit_);
   }
   bool AliasingEnabled() const { return aliasing_ != kNoAliasing; }
   int BytesUntilLimit(const char* ptr) const {
     return limit_ + static_cast<int>(buffer_end_ - ptr);
   }
   // Maximum number of sequential bytes that can be read starting from `ptr`.
   int MaximumReadSize(const char* ptr) const {
     return static_cast<int>(limit_end_ - ptr) + kSlopBytes;
   }
   // Returns true if more data is available, if false is returned one has to
   // call Done for further checks.
   bool DataAvailable(const char* ptr) { return ptr < limit_end_; }
 
  protected:
   // Returns true if limit (either an explicit limit or end of stream) is
   // reached. It aligns *ptr across buffer seams.
   // If limit is exceeded, it returns true and ptr is set to null.
   bool DoneWithCheck(const char** ptr, int d) {
     ABSL_DCHECK(*ptr);
     if (PROTOBUF_PREDICT_TRUE(*ptr < limit_end_)) return false;
     int overrun = static_cast<int>(*ptr - buffer_end_);
     ABSL_DCHECK_LE(overrun, kSlopBytes);  // Guaranteed by parse loop.
     if (overrun ==
         limit_) {  //  No need to flip buffers if we ended on a limit.
       // If we actually overrun the buffer and next_chunk_ is null, it means
       // the stream ended and we passed the stream end.
       if (overrun > 0 && next_chunk_ == nullptr) *ptr = nullptr;
       return true;
     }
     auto res = DoneFallback(overrun, d);
     *ptr = res.first;
     return res.second;
   }
 
   const char* InitFrom(absl::string_view flat) {
     overall_limit_ = 0;
     if (flat.size() > kSlopBytes) {
       limit_ = kSlopBytes;
       limit_end_ = buffer_end_ = flat.data() + flat.size() - kSlopBytes;
       next_chunk_ = patch_buffer_;
       if (aliasing_ == kOnPatch) aliasing_ = kNoDelta;
       return flat.data();
     } else {
       if (!flat.empty()) {
         std::memcpy(patch_buffer_, flat.data(), flat.size());
       }
       limit_ = 0;
       limit_end_ = buffer_end_ = patch_buffer_ + flat.size();
       next_chunk_ = nullptr;
       if (aliasing_ == kOnPatch) {
         aliasing_ = reinterpret_cast<std::uintptr_t>(flat.data()) -
                     reinterpret_cast<std::uintptr_t>(patch_buffer_);
       }
       return patch_buffer_;
     }
   }
 
   const char* InitFrom(io::ZeroCopyInputStream* zcis);
 
   const char* InitFrom(io::ZeroCopyInputStream* zcis, int limit) {
     if (limit == -1) return InitFrom(zcis);
     overall_limit_ = limit;
     auto res = InitFrom(zcis);
     limit_ = limit - static_cast<int>(buffer_end_ - res);
     limit_end_ = buffer_end_ + (std::min)(0, limit_);
     return res;
   }
 
  private:
   enum { kSlopBytes = 16, kPatchBufferSize = 32 };
   static_assert(kPatchBufferSize >= kSlopBytes * 2,
                 "Patch buffer needs to be at least large enough to hold all "
                 "the slop bytes from the previous buffer, plus the first "
                 "kSlopBytes from the next buffer.");
 
   const char* limit_end_;  // buffer_end_ + min(limit_, 0)
   const char* buffer_end_;
   const char* next_chunk_;
   int size_;
   int limit_;  // relative to buffer_end_;
   io::ZeroCopyInputStream* zcis_ = nullptr;
   char patch_buffer_[kPatchBufferSize] = {};
   enum { kNoAliasing = 0, kOnPatch = 1, kNoDelta = 2 };
   std::uintptr_t aliasing_ = kNoAliasing;
   // This variable is used to communicate how the parse ended, in order to
   // completely verify the parsed data. A wire-format parse can end because of
   // one of the following conditions:
   // 1) A parse can end on a pushed limit.
   // 2) A parse can end on End Of Stream (EOS).
   // 3) A parse can end on 0 tag (only valid for toplevel message).
   // 4) A parse can end on an end-group tag.
   // This variable should always be set to 0, which indicates case 1. If the
   // parse terminated due to EOS (case 2), it's set to 1. In case the parse
   // ended due to a terminating tag (case 3 and 4) it's set to (tag - 1).
   // This var doesn't really belong in EpsCopyInputStream and should be part of
   // the ParseContext, but case 2 is most easily and optimally implemented in
   // DoneFallback.
   uint32_t last_tag_minus_1_ = 0;
   int overall_limit_ = INT_MAX;  // Overall limit independent of pushed limits.
   // Pretty random large number that seems like a safe allocation on most
   // systems. TODO do we need to set this as build flag?
   enum { kSafeStringSize = 50000000 };
 
   // Advances to next buffer chunk returns a pointer to the same logical place
   // in the stream as set by overrun. Overrun indicates the position in the slop
   // region the parse was left (0 <= overrun <= kSlopBytes). Returns true if at
   // limit, at which point the returned pointer maybe null if there was an
   // error. The invariant of this function is that it's guaranteed that
   // kSlopBytes bytes can be accessed from the returned ptr. This function might
   // advance more buffers than one in the underlying ZeroCopyInputStream.
   std::pair<const char*, bool> DoneFallback(int overrun, int depth);
   // Advances to the next buffer, at most one call to Next() on the underlying
   // ZeroCopyInputStream is made. This function DOES NOT match the returned
   // pointer to where in the slop region the parse ends, hence no overrun
   // parameter. This is useful for string operations where you always copy
   // to the end of the buffer (including the slop region).
   const char* Next();
   // overrun is the location in the slop region the stream currently is
   // (0 <= overrun <= kSlopBytes). To prevent flipping to the next buffer of
   // the ZeroCopyInputStream in the case the parse will end in the last
   // kSlopBytes of the current buffer. depth is the current depth of nested
   // groups (or negative if the use case does not need careful tracking).
   inline const char* NextBuffer(int overrun, int depth);
   const char* SkipFallback(const char* ptr, int size);
   const char* AppendStringFallback(const char* ptr, int size, std::string* str);
   const char* ReadStringFallback(const char* ptr, int size, std::string* str);
   const char* ReadCordFallback(const char* ptr, int size, absl::Cord* cord);
   static bool ParseEndsInSlopRegion(const char* begin, int overrun, int depth);
   bool StreamNext(const void** data) {
     bool res = zcis_->Next(data, &size_);
     if (res) overall_limit_ -= size_;
     return res;
   }
   void StreamBackUp(int count) {
     zcis_->BackUp(count);
     overall_limit_ += count;
   }
 
   template <typename A>
   const char* AppendSize(const char* ptr, int size, const A& append) {
     int chunk_size = static_cast<int>(buffer_end_ + kSlopBytes - ptr);
     do {
       ABSL_DCHECK(size > chunk_size);
       if (next_chunk_ == nullptr) return nullptr;
       append(ptr, chunk_size);
       ptr += chunk_size;
       size -= chunk_size;
       // TODO Next calls NextBuffer which generates buffers with
       // overlap and thus incurs cost of copying the slop regions. This is not
       // necessary for reading strings. We should just call Next buffers.
       if (limit_ <= kSlopBytes) return nullptr;
       ptr = Next();
       if (ptr == nullptr) return nullptr;  // passed the limit
       ptr += kSlopBytes;
       chunk_size = static_cast<int>(buffer_end_ + kSlopBytes - ptr);
     } while (size > chunk_size);
     append(ptr, size);
     return ptr + size;
   }
 
   // AppendUntilEnd appends data until a limit (either a PushLimit or end of
   // stream. Normal payloads are from length delimited fields which have an
   // explicit size. Reading until limit only comes when the string takes
   // the place of a protobuf, ie RawMessage, lazy fields and implicit weak
   // messages. We keep these methods private and friend them.
   template <typename A>
   const char* AppendUntilEnd(const char* ptr, const A& append) {
     if (ptr - buffer_end_ > limit_) return nullptr;
     while (limit_ > kSlopBytes) {
       size_t chunk_size = buffer_end_ + kSlopBytes - ptr;
       append(ptr, chunk_size);
       ptr = Next();
       if (ptr == nullptr) return limit_end_;
       ptr += kSlopBytes;
     }
     auto end = buffer_end_ + limit_;
     ABSL_DCHECK(end >= ptr);
     append(ptr, end - ptr);
     return end;
   }
 
   PROTOBUF_NODISCARD const char* AppendString(const char* ptr,
                                               std::string* str) {
     return AppendUntilEnd(
         ptr, [str](const char* p, ptrdiff_t s) { str->append(p, s); });
   }
   friend class ImplicitWeakMessage;
 
   // Needs access to kSlopBytes.
   friend PROTOBUF_EXPORT std::pair<const char*, int32_t> ReadSizeFallback(
       const char* p, uint32_t res);
 };
 
 using LazyEagerVerifyFnType = const char* (*)(const char* ptr,
                                               ParseContext* ctx);
 using LazyEagerVerifyFnRef = std::remove_pointer<LazyEagerVerifyFnType>::type&;
 
 // ParseContext holds all data that is global to the entire parse. Most
 // importantly it contains the input stream, but also recursion depth and also
 // stores the end group tag, in case a parser ended on a endgroup, to verify
 // matching start/end group tags.
 class PROTOBUF_EXPORT ParseContext : public EpsCopyInputStream {
  public:
   struct Data {
     const DescriptorPool* pool = nullptr;
     MessageFactory* factory = nullptr;
   };
 
   template <typename... T>
   ParseContext(int depth, bool aliasing, const char** start, T&&... args)
       : EpsCopyInputStream(aliasing), depth_(depth) {
     *start = InitFrom(std::forward<T>(args)...);
   }
 
   struct Spawn {};
   static constexpr Spawn kSpawn = {};
 
   // Creates a new context from a given "ctx" to inherit a few attributes to
   // emulate continued parsing. For example, recursion depth or descriptor pools
   // must be passed down to a new "spawned" context to maintain the same parse
   // context. Note that the spawned context always disables aliasing (different
   // input).
   template <typename... T>
   ParseContext(Spawn, const ParseContext& ctx, const char** start, T&&... args)
       : EpsCopyInputStream(false),
         depth_(ctx.depth_),
         data_(ctx.data_)
   {
     *start = InitFrom(std::forward<T>(args)...);
   }
 
   // Move constructor and assignment operator are not supported because "ptr"
   // for parsing may have pointed to an inlined buffer (patch_buffer_) which can
   // be invalid afterwards.
   ParseContext(ParseContext&&) = delete;
   ParseContext& operator=(ParseContext&&) = delete;
   ParseContext& operator=(const ParseContext&) = delete;
 
   void TrackCorrectEnding() { group_depth_ = 0; }
 
   // Done should only be called when the parsing pointer is pointing to the
   // beginning of field data - that is, at a tag.  Or if it is NULL.
   bool Done(const char** ptr) { return DoneWithCheck(ptr, group_depth_); }
 
   int depth() const { return depth_; }
 
   Data& data() { return data_; }
   const Data& data() const { return data_; }
 
   const char* ParseMessage(MessageLite* msg, const char* ptr);
 
   // Read the length prefix, push the new limit, call the func(ptr), and then
   // pop the limit. Useful for situations that don't have an actual message.
   template <typename Func>
   PROTOBUF_NODISCARD const char* ParseLengthDelimitedInlined(const char*,
                                                              const Func& func);
 
   // Push the recursion depth, call the func(ptr), and then pop depth. Useful
   // for situations that don't have an actual message.
   template <typename Func>
   PROTOBUF_NODISCARD const char* ParseGroupInlined(const char* ptr,
                                                    uint32_t start_tag,
                                                    const Func& func);
 
   // Use a template to avoid the strong dep into TcParser. All callers will have
   // the dep.
   template <typename Parser = TcParser>
   PROTOBUF_ALWAYS_INLINE const char* ParseMessage(
       MessageLite* msg, const TcParseTableBase* tc_table, const char* ptr) {
     return ParseLengthDelimitedInlined(ptr, [&](const char* ptr) {
       return Parser::ParseLoop(msg, ptr, this, tc_table);
     });
   }
   template <typename Parser = TcParser>
   PROTOBUF_ALWAYS_INLINE const char* ParseGroup(
       MessageLite* msg, const TcParseTableBase* tc_table, const char* ptr,
       uint32_t start_tag) {
     return ParseGroupInlined(ptr, start_tag, [&](const char* ptr) {
       return Parser::ParseLoop(msg, ptr, this, tc_table);
     });
   }
 
   PROTOBUF_NODISCARD PROTOBUF_NDEBUG_INLINE const char* ParseGroup(
       MessageLite* msg, const char* ptr, uint32_t tag) {
     if (--depth_ < 0) return nullptr;
     group_depth_++;
     auto old_depth = depth_;
     auto old_group_depth = group_depth_;
     ptr = msg->_InternalParse(ptr, this);
     if (ptr != nullptr) {
       ABSL_DCHECK_EQ(old_depth, depth_);
       ABSL_DCHECK_EQ(old_group_depth, group_depth_);
     }
     group_depth_--;
     depth_++;
     if (PROTOBUF_PREDICT_FALSE(!ConsumeEndGroup(tag))) return nullptr;
     return ptr;
   }
 
  private:
   // Out-of-line routine to save space in ParseContext::ParseMessage<T>
   //   LimitToken old;
   //   ptr = ReadSizeAndPushLimitAndDepth(ptr, &old)
   // is equivalent to:
   //   int size = ReadSize(&ptr);
   //   if (!ptr) return nullptr;
   //   LimitToken old = PushLimit(ptr, size);
   //   if (--depth_ < 0) return nullptr;
   PROTOBUF_NODISCARD const char* ReadSizeAndPushLimitAndDepth(
       const char* ptr, LimitToken* old_limit);
 
   // As above, but fully inlined for the cases where we care about performance
   // more than size. eg TcParser.
   PROTOBUF_NODISCARD PROTOBUF_ALWAYS_INLINE const char*
   ReadSizeAndPushLimitAndDepthInlined(const char* ptr, LimitToken* old_limit);
 
   // The context keeps an internal stack to keep track of the recursive
   // part of the parse state.
   // Current depth of the active parser, depth counts down.
   // This is used to limit recursion depth (to prevent overflow on malicious
   // data), but is also used to index in stack_ to store the current state.
   int depth_;
   // Unfortunately necessary for the fringe case of ending on 0 or end-group tag
   // in the last kSlopBytes of a ZeroCopyInputStream chunk.
   int group_depth_ = INT_MIN;
   Data data_;
 };
 
 template <int>
 struct EndianHelper;
 
 template <>
 struct EndianHelper<1> {
   static uint8_t Load(const void* p) { return *static_cast<const uint8_t*>(p); }
 };
 
 template <>
 struct EndianHelper<2> {
   static uint16_t Load(const void* p) {
     uint16_t tmp;
     std::memcpy(&tmp, p, 2);
     return little_endian::ToHost(tmp);
   }
 };
 
 template <>
 struct EndianHelper<4> {
   static uint32_t Load(const void* p) {
     uint32_t tmp;
     std::memcpy(&tmp, p, 4);
     return little_endian::ToHost(tmp);
   }
 };
 
 template <>
 struct EndianHelper<8> {
   static uint64_t Load(const void* p) {
     uint64_t tmp;
     std::memcpy(&tmp, p, 8);
     return little_endian::ToHost(tmp);
   }
 };
 
 template <typename T>
 T UnalignedLoad(const char* p) {
   auto tmp = EndianHelper<sizeof(T)>::Load(p);
   T res;
   memcpy(&res, &tmp, sizeof(T));
   return res;
 }
 template <typename T, typename Void,
           typename = std::enable_if_t<std::is_same<Void, void>::value>>
 T UnalignedLoad(const Void* p) {
   return UnalignedLoad<T>(reinterpret_cast<const char*>(p));
 }
 
 PROTOBUF_EXPORT
 std::pair<const char*, uint32_t> VarintParseSlow32(const char* p, uint32_t res);
 PROTOBUF_EXPORT
 std::pair<const char*, uint64_t> VarintParseSlow64(const char* p, uint32_t res);
 
 inline const char* VarintParseSlow(const char* p, uint32_t res, uint32_t* out) {
   auto tmp = VarintParseSlow32(p, res);
   *out = tmp.second;
   return tmp.first;
 }
 
 inline const char* VarintParseSlow(const char* p, uint32_t res, uint64_t* out) {
   auto tmp = VarintParseSlow64(p, res);
   *out = tmp.second;
   return tmp.first;
 }
 
 #ifdef __aarch64__
 // Generally, speaking, the ARM-optimized Varint decode algorithm is to extract
 // and concatenate all potentially valid data bits, compute the actual length
 // of the Varint, and mask off the data bits which are not actually part of the
 // result.  More detail on the two main parts is shown below.
 //
 // 1) Extract and concatenate all potentially valid data bits.
 //    Two ARM-specific features help significantly:
 //    a) Efficient and non-destructive bit extraction (UBFX)
 //    b) A single instruction can perform both an OR with a shifted
 //       second operand in one cycle.  E.g., the following two lines do the same
 //       thing
 //       ```result = operand_1 | (operand2 << 7);```
 //       ```ORR %[result], %[operand_1], %[operand_2], LSL #7```
 //    The figure below shows the implementation for handling four chunks.
 //
 // Bits   32    31-24    23   22-16    15    14-8      7     6-0
 //      +----+---------+----+---------+----+---------+----+---------+
 //      |CB 3| Chunk 3 |CB 2| Chunk 2 |CB 1| Chunk 1 |CB 0| Chunk 0 |
 //      +----+---------+----+---------+----+---------+----+---------+
 //                |              |              |              |
 //               UBFX           UBFX           UBFX           UBFX    -- cycle 1
 //                |              |              |              |
 //                V              V              V              V
 //               Combined LSL #7 and ORR     Combined LSL #7 and ORR  -- cycle 2
 //                                 |             |
 //                                 V             V
 //                            Combined LSL #14 and ORR                -- cycle 3
 //                                       |
 //                                       V
 //                                Parsed bits 0-27
 //
 //
 // 2) Calculate the index of the cleared continuation bit in order to determine
 //    where the encoded Varint ends and the size of the decoded value.  The
 //    easiest way to do this is mask off all data bits, leaving just the
 //    continuation bits.  We actually need to do the masking on an inverted
 //    copy of the data, which leaves a 1 in all continuation bits which were
 //    originally clear.  The number of trailing zeroes in this value indicates
 //    the size of the Varint.
 //
 //  AND  0x80    0x80    0x80    0x80    0x80    0x80    0x80    0x80
 //
 // Bits   63      55      47      39      31      23      15       7
 //      +----+--+----+--+----+--+----+--+----+--+----+--+----+--+----+--+
 // ~    |CB 7|  |CB 6|  |CB 5|  |CB 4|  |CB 3|  |CB 2|  |CB 1|  |CB 0|  |
 //      +----+--+----+--+----+--+----+--+----+--+----+--+----+--+----+--+
 //         |       |       |       |       |       |       |       |
 //         V       V       V       V       V       V       V       V
 // Bits   63      55      47      39      31      23      15       7
 //      +----+--+----+--+----+--+----+--+----+--+----+--+----+--+----+--+
 //      |~CB 7|0|~CB 6|0|~CB 5|0|~CB 4|0|~CB 3|0|~CB 2|0|~CB 1|0|~CB 0|0|
 //      +----+--+----+--+----+--+----+--+----+--+----+--+----+--+----+--+
 //                                      |
 //                                     CTZ
 //                                      V
 //                     Index of first cleared continuation bit
 //
 //
 // While this is implemented in C++ significant care has been taken to ensure
 // the compiler emits the best instruction sequence.  In some cases we use the
 // following two functions to manipulate the compiler's scheduling decisions.
 //
 // Controls compiler scheduling by telling it that the first value is modified
 // by the second value the callsite.  This is useful if non-critical path
 // instructions are too aggressively scheduled, resulting in a slowdown of the
 // actual critical path due to opportunity costs.  An example usage is shown
 // where a false dependence of num_bits on result is added to prevent checking
 // for a very unlikely error until all critical path instructions have been
 // fetched.
 //
 // ```
 // num_bits = <multiple operations to calculate new num_bits value>
 // result = <multiple operations to calculate result>
 // num_bits = ValueBarrier(num_bits, result);
 // if (num_bits == 63) {
 //   ABSL_LOG(FATAL) << "Invalid num_bits value";
 // }
 // ```
 // Falsely indicate that the specific value is modified at this location.  This
 // prevents code which depends on this value from being scheduled earlier.
 template <typename V1Type>
 PROTOBUF_ALWAYS_INLINE inline V1Type ValueBarrier(V1Type value1) {
   asm("" : "+r"(value1));
   return value1;
 }
 
 template <typename V1Type, typename V2Type>
 PROTOBUF_ALWAYS_INLINE inline V1Type ValueBarrier(V1Type value1,
                                                   V2Type value2) {
   asm("" : "+r"(value1) : "r"(value2));
   return value1;
 }
 
 // Performs a 7 bit UBFX (Unsigned Bit Extract) starting at the indicated bit.
 static PROTOBUF_ALWAYS_INLINE inline uint64_t Ubfx7(uint64_t data,
                                                     uint64_t start) {
   return ValueBarrier((data >> start) & 0x7f);
 }
 
 PROTOBUF_ALWAYS_INLINE inline uint64_t ExtractAndMergeTwoChunks(
     uint64_t data, uint64_t first_byte) {
   ABSL_DCHECK_LE(first_byte, 6U);
   uint64_t first = Ubfx7(data, first_byte * 8);
   uint64_t second = Ubfx7(data, (first_byte + 1) * 8);
   return ValueBarrier(first | (second << 7));
 }
 
 struct SlowPathEncodedInfo {
   const char* p;
   uint64_t last8;
   uint64_t valid_bits;
   uint64_t valid_chunk_bits;
   uint64_t masked_cont_bits;
 };
 
 // Performs multiple actions which are identical between 32 and 64 bit Varints
 // in order to compute the length of the encoded Varint and compute the new
 // of p.
 PROTOBUF_ALWAYS_INLINE inline SlowPathEncodedInfo ComputeLengthAndUpdateP(
     const char* p) {
   SlowPathEncodedInfo result;
   // Load the last two bytes of the encoded Varint.
   std::memcpy(&result.last8, p + 2, sizeof(result.last8));
   uint64_t mask = ValueBarrier(0x8080808080808080);
   // Only set continuation bits remain
   result.masked_cont_bits = ValueBarrier(mask & ~result.last8);
   // The first cleared continuation bit is the most significant 1 in the
   // reversed value.  Result is undefined for an input of 0 and we handle that
   // case below.
   result.valid_bits = absl::countr_zero(result.masked_cont_bits);
   // Calculates the number of chunks in the encoded Varint.  This value is low
   // by three as neither the cleared continuation chunk nor the first two chunks
   // are counted.
   uint64_t set_continuation_bits = result.valid_bits >> 3;
   // Update p to point past the encoded Varint.
   result.p = p + set_continuation_bits + 3;
   // Calculate number of valid data bits in the decoded value so invalid bits
   // can be masked off.  Value is too low by 14 but we account for that when
   // calculating the mask.
   result.valid_chunk_bits = result.valid_bits - set_continuation_bits;
   return result;
 }
 
 inline PROTOBUF_ALWAYS_INLINE std::pair<const char*, uint64_t>
 VarintParseSlowArm64(const char* p, uint64_t first8) {
   constexpr uint64_t kResultMaskUnshifted = 0xffffffffffffc000ULL;
   constexpr uint64_t kFirstResultBitChunk2 = 2 * 7;
   constexpr uint64_t kFirstResultBitChunk4 = 4 * 7;
   constexpr uint64_t kFirstResultBitChunk6 = 6 * 7;
   constexpr uint64_t kFirstResultBitChunk8 = 8 * 7;
 
   SlowPathEncodedInfo info = ComputeLengthAndUpdateP(p);
   // Extract data bits from the low six chunks.  This includes chunks zero and
   // one which we already know are valid.
   uint64_t merged_01 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/0);
   uint64_t merged_23 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/2);
   uint64_t merged_45 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/4);
   // Low 42 bits of decoded value.
   uint64_t result = merged_01 | (merged_23 << kFirstResultBitChunk2) |
                     (merged_45 << kFirstResultBitChunk4);
   // This immediate ends in 14 zeroes since valid_chunk_bits is too low by 14.
   uint64_t result_mask = kResultMaskUnshifted << info.valid_chunk_bits;
   //  iff the Varint i invalid.
   if (PROTOBUF_PREDICT_FALSE(info.masked_cont_bits == 0)) {
     return {nullptr, 0};
   }
   // Test for early exit if Varint does not exceed 6 chunks.  Branching on one
   // bit is faster on ARM than via a compare and branch.
   if (PROTOBUF_PREDICT_FALSE((info.valid_bits & 0x20) != 0)) {
     // Extract data bits from high four chunks.
     uint64_t merged_67 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/6);
     // Last two chunks come from last two bytes of info.last8.
     uint64_t merged_89 =
         ExtractAndMergeTwoChunks(info.last8, /*first_chunk=*/6);
     result |= merged_67 << kFirstResultBitChunk6;
     result |= merged_89 << kFirstResultBitChunk8;
     // Handle an invalid Varint with all 10 continuation bits set.
   }
   // Mask off invalid data bytes.
   result &= ~result_mask;
   return {info.p, result};
 }
 
 // See comments in VarintParseSlowArm64 for a description of the algorithm.
 // Differences in the 32 bit version are noted below.
 inline PROTOBUF_ALWAYS_INLINE std::pair<const char*, uint32_t>
 VarintParseSlowArm32(const char* p, uint64_t first8) {
   constexpr uint64_t kResultMaskUnshifted = 0xffffffffffffc000ULL;
   constexpr uint64_t kFirstResultBitChunk1 = 1 * 7;
   constexpr uint64_t kFirstResultBitChunk3 = 3 * 7;
 
   // This also skips the slop bytes.
   SlowPathEncodedInfo info = ComputeLengthAndUpdateP(p);
   // Extract data bits from chunks 1-4.  Chunk zero is merged in below.
   uint64_t merged_12 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/1);
   uint64_t merged_34 = ExtractAndMergeTwoChunks(first8, /*first_chunk=*/3);
   first8 = ValueBarrier(first8, p);
   uint64_t result = Ubfx7(first8, /*start=*/0);
   result = ValueBarrier(result | merged_12 << kFirstResultBitChunk1);
   result = ValueBarrier(result | merged_34 << kFirstResultBitChunk3);
   uint64_t result_mask = kResultMaskUnshifted << info.valid_chunk_bits;
   result &= ~result_mask;
   // It is extremely unlikely that a Varint is invalid so checking that
   // condition isn't on the critical path. Here we make sure that we don't do so
   // until result has been computed.
   info.masked_cont_bits = ValueBarrier(info.masked_cont_bits, result);
   if (PROTOBUF_PREDICT_FALSE(info.masked_cont_bits == 0)) {
     return {nullptr, 0};
   }
   return {info.p, result};
 }
 
 static const char* VarintParseSlowArm(const char* p, uint32_t* out,
                                       uint64_t first8) {
   auto tmp = VarintParseSlowArm32(p, first8);
   *out = tmp.second;
   return tmp.first;
 }
 
 static const char* VarintParseSlowArm(const char* p, uint64_t* out,
                                       uint64_t first8) {
   auto tmp = VarintParseSlowArm64(p, first8);
   *out = tmp.second;
   return tmp.first;
 }
 #endif
 
 // The caller must ensure that p points to at least 10 valid bytes.
 template <typename T>
 PROTOBUF_NODISCARD const char* VarintParse(const char* p, T* out) {
 #if defined(__aarch64__) && defined(ABSL_IS_LITTLE_ENDIAN)
   // This optimization is not supported in big endian mode
   uint64_t first8;
   std::memcpy(&first8, p, sizeof(first8));
   if (PROTOBUF_PREDICT_TRUE((first8 & 0x80) == 0)) {
     *out = static_cast<uint8_t>(first8);
     return p + 1;
   }
   if (PROTOBUF_PREDICT_TRUE((first8 & 0x8000) == 0)) {
     uint64_t chunk1;
     uint64_t chunk2;
     // Extracting the two chunks this way gives a speedup for this path.
     chunk1 = Ubfx7(first8, 0);
     chunk2 = Ubfx7(first8, 8);
     *out = chunk1 | (chunk2 << 7);
     return p + 2;
   }
   return VarintParseSlowArm(p, out, first8);
 #else   // __aarch64__
   auto ptr = reinterpret_cast<const uint8_t*>(p);
   uint32_t res = ptr[0];
   if ((res & 0x80) == 0) {
     *out = res;
     return p + 1;
   }
   return VarintParseSlow(p, res, out);
 #endif  // __aarch64__
 }
 
 // Used for tags, could read up to 5 bytes which must be available.
 // Caller must ensure it's safe to call.
 
 PROTOBUF_EXPORT
 std::pair<const char*, uint32_t> ReadTagFallback(const char* p, uint32_t res);
 
 // Same as ParseVarint but only accept 5 bytes at most.
 inline const char* ReadTag(const char* p, uint32_t* out,
                            uint32_t /*max_tag*/ = 0) {
   uint32_t res = static_cast<uint8_t>(p[0]);
   if (res < 128) {
     *out = res;
     return p + 1;
   }
   uint32_t second = static_cast<uint8_t>(p[1]);
   res += (second - 1) << 7;
   if (second < 128) {
     *out = res;
     return p + 2;
   }
   auto tmp = ReadTagFallback(p, res);
   *out = tmp.second;
   return tmp.first;
 }
 
 // As above, but optimized to consume very few registers while still being fast,
 // ReadTagInlined is useful for callers that don't mind the extra code but would
 // like to avoid an extern function call causing spills into the stack.
 //
 // Two support routines for ReadTagInlined come first...
 template <class T>
 PROTOBUF_NODISCARD PROTOBUF_ALWAYS_INLINE constexpr T RotateLeft(
     T x, int s) noexcept {
   return static_cast<T>(x << (s & (std::numeric_limits<T>::digits - 1))) |
          static_cast<T>(x >> ((-s) & (std::numeric_limits<T>::digits - 1)));
 }
 
 PROTOBUF_NODISCARD inline PROTOBUF_ALWAYS_INLINE uint64_t
 RotRight7AndReplaceLowByte(uint64_t res, const char& byte) {
   // TODO: remove the inline assembly
 #if defined(__x86_64__) && defined(__GNUC__)
   // This will only use one register for `res`.
   // `byte` comes as a reference to allow the compiler to generate code like:
   //
   //   rorq    $7, %rcx
   //   movb    1(%rax), %cl
   //
   // which avoids loading the incoming bytes into a separate register first.
   asm("ror $7,%0\n\t"
       "movb %1,%b0"
       : "+r"(res)
       : "m"(byte));
 #else
   res = RotateLeft(res, -7);
   res = res & ~0xFF;
   res |= 0xFF & byte;
 #endif
   return res;
 }
 
 inline PROTOBUF_ALWAYS_INLINE const char* ReadTagInlined(const char* ptr,
                                                          uint32_t* out) {
   uint64_t res = 0xFF & ptr[0];
   if (PROTOBUF_PREDICT_FALSE(res >= 128)) {
     res = RotRight7AndReplaceLowByte(res, ptr[1]);
     if (PROTOBUF_PREDICT_FALSE(res & 0x80)) {
       res = RotRight7AndReplaceLowByte(res, ptr[2]);
       if (PROTOBUF_PREDICT_FALSE(res & 0x80)) {
         res = RotRight7AndReplaceLowByte(res, ptr[3]);
         if (PROTOBUF_PREDICT_FALSE(res & 0x80)) {
           // Note: this wouldn't work if res were 32-bit,
           // because then replacing the low byte would overwrite
           // the bottom 4 bits of the result.
           res = RotRight7AndReplaceLowByte(res, ptr[4]);
           if (PROTOBUF_PREDICT_FALSE(res & 0x80)) {
             // The proto format does not permit longer than 5-byte encodings for
             // tags.
             *out = 0;
             return nullptr;
           }
           *out = static_cast<uint32_t>(RotateLeft(res, 28));
 #if defined(__GNUC__)
           // Note: this asm statement prevents the compiler from
           // trying to share the "return ptr + constant" among all
           // branches.
           asm("" : "+r"(ptr));
 #endif
           return ptr + 5;
         }
         *out = static_cast<uint32_t>(RotateLeft(res, 21));
         return ptr + 4;
       }
       *out = static_cast<uint32_t>(RotateLeft(res, 14));
       return ptr + 3;
     }
     *out = static_cast<uint32_t>(RotateLeft(res, 7));
     return ptr + 2;
   }
   *out = static_cast<uint32_t>(res);
   return ptr + 1;
 }
 
 // Decode 2 consecutive bytes of a varint and returns the value, shifted left
 // by 1. It simultaneous updates *ptr to *ptr + 1 or *ptr + 2 depending if the
 // first byte's continuation bit is set.
 // If bit 15 of return value is set (equivalent to the continuation bits of both
 // bytes being set) the varint continues, otherwise the parse is done. On x86
 // movsx eax, dil
 // and edi, eax
 // add eax, edi
 // adc [rsi], 1
 inline uint32_t DecodeTwoBytes(const char** ptr) {
   uint32_t value = UnalignedLoad<uint16_t>(*ptr);
   // Sign extend the low byte continuation bit
   uint32_t x = static_cast<int8_t>(value);
   value &= x;  // Mask out the high byte iff no continuation
   // This add is an amazing operation, it cancels the low byte continuation bit
   // from y transferring it to the carry. Simultaneously it also shifts the 7
   // LSB left by one tightly against high byte varint bits. Hence value now
   // contains the unpacked value shifted left by 1.
   value += x;
   // Use the carry to update the ptr appropriately.
   *ptr += value < x ? 2 : 1;
   return value;
 }
 
 // More efficient varint parsing for big varints
 inline const char* ParseBigVarint(const char* p, uint64_t* out) {
   auto pnew = p;
   auto tmp = DecodeTwoBytes(&pnew);
   uint64_t res = tmp >> 1;
   if (PROTOBUF_PREDICT_TRUE(static_cast<std::int16_t>(tmp) >= 0)) {
     *out = res;
     return pnew;
   }
   for (std::uint32_t i = 1; i < 5; i++) {
     pnew = p + 2 * i;
     tmp = DecodeTwoBytes(&pnew);
     res += (static_cast<std::uint64_t>(tmp) - 2) << (14 * i - 1);
     if (PROTOBUF_PREDICT_TRUE(static_cast<std::int16_t>(tmp) >= 0)) {
       *out = res;
       return pnew;
     }
   }
   return nullptr;
 }
 
 PROTOBUF_EXPORT
 std::pair<const char*, int32_t> ReadSizeFallback(const char* p, uint32_t first);
 // Used for tags, could read up to 5 bytes which must be available. Additionally
 // it makes sure the unsigned value fits a int32_t, otherwise returns nullptr.
 // Caller must ensure its safe to call.
 inline uint32_t ReadSize(const char** pp) {
   auto p = *pp;
   uint32_t res = static_cast<uint8_t>(p[0]);
   if (res < 128) {
     *pp = p + 1;
     return res;
   }
   auto x = ReadSizeFallback(p, res);
   *pp = x.first;
   return x.second;
 }
 
 // Some convenience functions to simplify the generated parse loop code.
 // Returning the value and updating the buffer pointer allows for nicer
 // function composition. We rely on the compiler to inline this.
 // Also in debug compiles having local scoped variables tend to generated
 // stack frames that scale as O(num fields).
 inline uint64_t ReadVarint64(const char** p) {
   uint64_t tmp;
   *p = VarintParse(*p, &tmp);
   return tmp;
 }
 
 inline uint32_t ReadVarint32(const char** p) {
   uint32_t tmp;
   *p = VarintParse(*p, &tmp);
   return tmp;
 }
 
 inline int64_t ReadVarintZigZag64(const char** p) {
   uint64_t tmp;
   *p = VarintParse(*p, &tmp);
   return WireFormatLite::ZigZagDecode64(tmp);
 }
 
 inline int32_t ReadVarintZigZag32(const char** p) {
   uint64_t tmp;
   *p = VarintParse(*p, &tmp);
   return WireFormatLite::ZigZagDecode32(static_cast<uint32_t>(tmp));
 }
 
 template <typename Func>
 PROTOBUF_NODISCARD inline PROTOBUF_ALWAYS_INLINE const char*
 ParseContext::ParseLengthDelimitedInlined(const char* ptr, const Func& func) {
   LimitToken old;
   ptr = ReadSizeAndPushLimitAndDepthInlined(ptr, &old);
   if (ptr == nullptr) return ptr;
   auto old_depth = depth_;
   PROTOBUF_ALWAYS_INLINE_CALL ptr = func(ptr);
   if (ptr != nullptr) ABSL_DCHECK_EQ(old_depth, depth_);
   depth_++;
   if (!PopLimit(std::move(old))) return nullptr;
   return ptr;
 }
 
 template <typename Func>
 PROTOBUF_NODISCARD inline PROTOBUF_ALWAYS_INLINE const char*
 ParseContext::ParseGroupInlined(const char* ptr, uint32_t start_tag,
                                 const Func& func) {
   if (--depth_ < 0) return nullptr;
   group_depth_++;
   auto old_depth = depth_;
   auto old_group_depth = group_depth_;
   PROTOBUF_ALWAYS_INLINE_CALL ptr = func(ptr);
   if (ptr != nullptr) {
     ABSL_DCHECK_EQ(old_depth, depth_);
     ABSL_DCHECK_EQ(old_group_depth, group_depth_);
   }
   group_depth_--;
   depth_++;
   if (PROTOBUF_PREDICT_FALSE(!ConsumeEndGroup(start_tag))) return nullptr;
   return ptr;
 }
 
 inline const char* ParseContext::ReadSizeAndPushLimitAndDepthInlined(
     const char* ptr, LimitToken* old_limit) {
   int size = ReadSize(&ptr);
   if (PROTOBUF_PREDICT_FALSE(!ptr) || depth_ <= 0) {
     return nullptr;
   }
   *old_limit = PushLimit(ptr, size);
   --depth_;
   return ptr;
 }
 
 template <typename Tag, typename T>
 const char* EpsCopyInputStream::ReadRepeatedFixed(const char* ptr,
                                                   Tag expected_tag,
                                                   RepeatedField<T>* out) {
   do {
     out->Add(UnalignedLoad<T>(ptr));
     ptr += sizeof(T);
     if (PROTOBUF_PREDICT_FALSE(ptr >= limit_end_)) return ptr;
   } while (UnalignedLoad<Tag>(ptr) == expected_tag && (ptr += sizeof(Tag)));
   return ptr;
 }
 
 // Add any of the following lines to debug which parse function is failing.
 
 #define GOOGLE_PROTOBUF_ASSERT_RETURN(predicate, ret) \
   if (!(predicate)) {                                  \
     /*  ::raise(SIGINT);  */                           \
     /*  ABSL_LOG(ERROR) << "Parse failure";  */        \
     return ret;                                        \
   }
 
 #define GOOGLE_PROTOBUF_PARSER_ASSERT(predicate) \
   GOOGLE_PROTOBUF_ASSERT_RETURN(predicate, nullptr)
 
 template <typename T>
 const char* EpsCopyInputStream::ReadPackedFixed(const char* ptr, int size,
                                                 RepeatedField<T>* out) {
   GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
   int nbytes = static_cast<int>(buffer_end_ + kSlopBytes - ptr);
   while (size > nbytes) {
     int num = nbytes / sizeof(T);
     int old_entries = out->size();
     out->Reserve(old_entries + num);
     int block_size = num * sizeof(T);
     auto dst = out->AddNAlreadyReserved(num);
 #ifdef ABSL_IS_LITTLE_ENDIAN
     std::memcpy(dst, ptr, block_size);
 #else
     for (int i = 0; i < num; i++)
       dst[i] = UnalignedLoad<T>(ptr + i * sizeof(T));
 #endif
     size -= block_size;
     if (limit_ <= kSlopBytes) return nullptr;
     ptr = Next();
     if (ptr == nullptr) return nullptr;
     ptr += kSlopBytes - (nbytes - block_size);
     nbytes = static_cast<int>(buffer_end_ + kSlopBytes - ptr);
   }
   int num = size / sizeof(T);
   int block_size = num * sizeof(T);
   if (num == 0) return size == block_size ? ptr : nullptr;
   int old_entries = out->size();
   out->Reserve(old_entries + num);
   auto dst = out->AddNAlreadyReserved(num);
 #ifdef ABSL_IS_LITTLE_ENDIAN
   ABSL_CHECK(dst != nullptr) << out << "," << num;
   std::memcpy(dst, ptr, block_size);
 #else
   for (int i = 0; i < num; i++) dst[i] = UnalignedLoad<T>(ptr + i * sizeof(T));
 #endif
   ptr += block_size;
   if (size != block_size) return nullptr;
   return ptr;
 }
 
 template <typename Add>
 const char* ReadPackedVarintArray(const char* ptr, const char* end, Add add) {
   while (ptr < end) {
     uint64_t varint;
     ptr = VarintParse(ptr, &varint);
     if (ptr == nullptr) return nullptr;
     add(varint);
   }
   return ptr;
 }
 
 template <typename Add, typename SizeCb>
 const char* EpsCopyInputStream::ReadPackedVarint(const char* ptr, Add add,
                                                  SizeCb size_callback) {
   int size = ReadSize(&ptr);
   size_callback(size);
 
   GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
   int chunk_size = static_cast<int>(buffer_end_ - ptr);
   while (size > chunk_size) {
     ptr = ReadPackedVarintArray(ptr, buffer_end_, add);
     if (ptr == nullptr) return nullptr;
     int overrun = static_cast<int>(ptr - buffer_end_);
     ABSL_DCHECK(overrun >= 0 && overrun <= kSlopBytes);
     if (size - chunk_size <= kSlopBytes) {
       // The current buffer contains all the information needed, we don't need
       // to flip buffers. However we must parse from a buffer with enough space
       // so we are not prone to a buffer overflow.
       char buf[kSlopBytes + 10] = {};
       std::memcpy(buf, buffer_end_, kSlopBytes);
       ABSL_CHECK_LE(size - chunk_size, kSlopBytes);
       auto end = buf + (size - chunk_size);
       auto res = ReadPackedVarintArray(buf + overrun, end, add);
       if (res == nullptr || res != end) return nullptr;
       return buffer_end_ + (res - buf);
     }
     size -= overrun + chunk_size;
     ABSL_DCHECK_GT(size, 0);
     // We must flip buffers
     if (limit_ <= kSlopBytes) return nullptr;
     ptr = Next();
     if (ptr == nullptr) return nullptr;
     ptr += overrun;
     chunk_size = static_cast<int>(buffer_end_ - ptr);
   }
   auto end = ptr + size;
   ptr = ReadPackedVarintArray(ptr, end, add);
   return end == ptr ? ptr : nullptr;
 }
 
 // Helper for verification of utf8
 PROTOBUF_EXPORT
 bool VerifyUTF8(absl::string_view s, const char* field_name);
 
 inline bool VerifyUTF8(const std::string* s, const char* field_name) {
   return VerifyUTF8(*s, field_name);
 }
 
 // All the string parsers with or without UTF checking and for all CTypes.
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* InlineGreedyStringParser(
     std::string* s, const char* ptr, ParseContext* ctx);
 
 PROTOBUF_NODISCARD inline const char* InlineCordParser(::absl::Cord* cord,
                                                        const char* ptr,
                                                        ParseContext* ctx) {
   int size = ReadSize(&ptr);
   if (!ptr) return nullptr;
   return ctx->ReadCord(ptr, size, cord);
 }
 
 
 template <typename T>
 PROTOBUF_NODISCARD const char* FieldParser(uint64_t tag, T& field_parser,
                                            const char* ptr, ParseContext* ctx) {
   uint32_t number = tag >> 3;
   GOOGLE_PROTOBUF_PARSER_ASSERT(number != 0);
   using WireType = internal::WireFormatLite::WireType;
   switch (tag & 7) {
     case WireType::WIRETYPE_VARINT: {
       uint64_t value;
       ptr = VarintParse(ptr, &value);
       GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
       field_parser.AddVarint(number, value);
       break;
     }
     case WireType::WIRETYPE_FIXED64: {
       uint64_t value = UnalignedLoad<uint64_t>(ptr);
       ptr += 8;
       field_parser.AddFixed64(number, value);
       break;
     }
     case WireType::WIRETYPE_LENGTH_DELIMITED: {
       ptr = field_parser.ParseLengthDelimited(number, ptr, ctx);
       GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
       break;
     }
     case WireType::WIRETYPE_START_GROUP: {
       ptr = field_parser.ParseGroup(number, ptr, ctx);
       GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
       break;
     }
     case WireType::WIRETYPE_END_GROUP: {
       ABSL_LOG(FATAL) << "Can't happen";
       break;
     }
     case WireType::WIRETYPE_FIXED32: {
       uint32_t value = UnalignedLoad<uint32_t>(ptr);
       ptr += 4;
       field_parser.AddFixed32(number, value);
       break;
     }
     default:
       return nullptr;
   }
   return ptr;
 }
 
 template <typename T>
 PROTOBUF_NODISCARD const char* WireFormatParser(T& field_parser,
                                                 const char* ptr,
                                                 ParseContext* ctx) {
   while (!ctx->Done(&ptr)) {
     uint32_t tag;
     ptr = ReadTag(ptr, &tag);
     GOOGLE_PROTOBUF_PARSER_ASSERT(ptr != nullptr);
     if (tag == 0 || (tag & 7) == 4) {
       ctx->SetLastTag(tag);
       return ptr;
     }
     ptr = FieldParser(tag, field_parser, ptr, ctx);
     GOOGLE_PROTOBUF_PARSER_ASSERT(ptr != nullptr);
   }
   return ptr;
 }
 
 // The packed parsers parse repeated numeric primitives directly into  the
 // corresponding field
 
 // These are packed varints
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedInt32Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedUInt32Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedInt64Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedUInt64Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedSInt32Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedSInt64Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedEnumParser(
     void* object, const char* ptr, ParseContext* ctx);
 
 template <typename T>
 PROTOBUF_NODISCARD const char* PackedEnumParser(void* object, const char* ptr,
                                                 ParseContext* ctx,
                                                 bool (*is_valid)(int),
                                                 InternalMetadata* metadata,
                                                 int field_num) {
   return ctx->ReadPackedVarint(
       ptr, [object, is_valid, metadata, field_num](int32_t val) {
         if (is_valid(val)) {
           static_cast<RepeatedField<int>*>(object)->Add(val);
         } else {
           WriteVarint(field_num, val, metadata->mutable_unknown_fields<T>());
         }
       });
 }
 
 template <typename T>
 PROTOBUF_NODISCARD const char* PackedEnumParserArg(
     void* object, const char* ptr, ParseContext* ctx,
     bool (*is_valid)(const void*, int), const void* data,
     InternalMetadata* metadata, int field_num) {
   return ctx->ReadPackedVarint(
       ptr, [object, is_valid, data, metadata, field_num](int32_t val) {
         if (is_valid(data, val)) {
           static_cast<RepeatedField<int>*>(object)->Add(val);
         } else {
           WriteVarint(field_num, val, metadata->mutable_unknown_fields<T>());
         }
       });
 }
 
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedBoolParser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedFixed32Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedSFixed32Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedFixed64Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedSFixed64Parser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedFloatParser(
     void* object, const char* ptr, ParseContext* ctx);
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* PackedDoubleParser(
     void* object, const char* ptr, ParseContext* ctx);
 
 // This is the only recursive parser.
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* UnknownGroupLiteParse(
     std::string* unknown, const char* ptr, ParseContext* ctx);
 // This is a helper to for the UnknownGroupLiteParse but is actually also
 // useful in the generated code. It uses overload on std::string* vs
 // UnknownFieldSet* to make the generated code isomorphic between full and lite.
 PROTOBUF_NODISCARD PROTOBUF_EXPORT const char* UnknownFieldParse(
     uint32_t tag, std::string* unknown, const char* ptr, ParseContext* ctx);
 
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
 
 #include "google/protobuf/port_undef.inc"
 
 #endif  // GOOGLE_PROTOBUF_PARSE_CONTEXT_H__

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