protobuf/upb/wire/reader.c

/*
 * Copyright (c) 2009-2021, Google LLC
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 */

#include "upb/wire/reader.h"

// Must be last.
#include "upb/port/def.inc"
#include "upb/wire/eps_copy_input_stream.h"
#include "upb/wire/types.h"

UPB_NOINLINE _upb_WireReader_ReadLongVarintRet
_upb_WireReader_ReadLongVarint(const char* ptr, uint64_t val) {
  _upb_WireReader_ReadLongVarintRet ret = {NULL, 0};
  uint64_t byte;
  int i;
  for (i = 1; i < 10; i++) {
    byte = (uint8_t)ptr[i];
    val += (byte - 1) << (i * 7);
    if (!(byte & 0x80)) {
      ret.ptr = ptr + i + 1;
      ret.val = val;
      return ret;
    }
  }
  return ret;
}

const char* upb_WireReader_SkipGroup(const char* ptr, uint32_t tag,
                                     int depth_limit,
                                     upb_EpsCopyInputStream* stream) {
  if (--depth_limit == 0) return NULL;
  uint32_t end_group_tag = (tag & ~7ULL) | kUpb_WireType_EndGroup;
  while (!upb_EpsCopyInputStream_IsDone(stream, &ptr)) {
    uint32_t tag;
    ptr = upb_WireReader_ReadTag(ptr, &tag);
    if (!ptr) return NULL;
    if (tag == end_group_tag) return ptr;
    ptr = upb_WireReader_SkipValue(ptr, tag, depth_limit, stream);
    if (!ptr) return NULL;
  }
  return ptr;
}