upb/message/internal/message.c

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  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

#include "upb/message/internal/message.h"

#include <math.h>
#include <string.h>

#include "upb/base/internal/log2.h"
#include "upb/mem/arena.h"

// Must be last.
#include "upb/port/def.inc"

const float kUpb_FltInfinity = INFINITY;
const double kUpb_Infinity = INFINITY;
const double kUpb_NaN = NAN;

static const size_t realloc_overhead = sizeof(upb_Message_InternalData);

bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
                                       upb_Arena* arena) {
  upb_Message_Internal* in = upb_Message_Getinternal(msg);
  if (!in->internal) {
    // No internal data, allocate from scratch.
    size_t size = UPB_MAX(128, upb_Log2CeilingSize(need + realloc_overhead));
    upb_Message_InternalData* internal = upb_Arena_Malloc(arena, size);
    if (!internal) return false;
    internal->size = size;
    internal->unknown_end = realloc_overhead;
    internal->ext_begin = size;
    in->internal = internal;
  } else if (in->internal->ext_begin - in->internal->unknown_end < need) {
    // Internal data is too small, reallocate.
    size_t new_size = upb_Log2CeilingSize(in->internal->size + need);
    size_t ext_bytes = in->internal->size - in->internal->ext_begin;
    size_t new_ext_begin = new_size - ext_bytes;
    upb_Message_InternalData* internal =
        upb_Arena_Realloc(arena, in->internal, in->internal->size, new_size);
    if (!internal) return false;
    if (ext_bytes) {
      // Need to move extension data to the end.
      char* ptr = (char*)internal;
      memmove(ptr + new_ext_begin, ptr + internal->ext_begin, ext_bytes);
    }
    internal->ext_begin = new_ext_begin;
    internal->size = new_size;
    in->internal = internal;
  }
  UPB_ASSERT(in->internal->ext_begin - in->internal->unknown_end >= need);
  return true;
}