Inside Bitcoin

1// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5#include "util/logging.h"
6
7#include <errno.h>
8#include <stdarg.h>
9#include <stdio.h>
10#include <stdlib.h>
11
12#include <limits>
13
14#include "leveldb/env.h"
15#include "leveldb/slice.h"
16
17namespace leveldb {
18
19void AppendNumberTo(std::string* str, uint64_t num) {
20  char buf[30];
21  snprintf(buf, sizeof(buf), "%llu", (unsigned long long)num);
22  str->append(buf);
23}
24
25void AppendEscapedStringTo(std::string* str, const Slice& value) {
26  for (size_t i = 0; i < value.size(); i++) {
27    char c = value[i];
28    if (c >= ' ' && c <= '~') {
29      str->push_back(c);
30    } else {
31      char buf[10];
32      snprintf(buf, sizeof(buf), "\\x%02x",
33               static_cast<unsigned int>(c) & 0xff);
34      str->append(buf);
35    }
36  }
37}
38
39std::string NumberToString(uint64_t num) {
40  std::string r;
41  AppendNumberTo(&r, num);
42  return r;
43}
44
45std::string EscapeString(const Slice& value) {
46  std::string r;
47  AppendEscapedStringTo(&r, value);
48  return r;
49}
50
51bool ConsumeDecimalNumber(Slice* in, uint64_t* val) {
52  // Constants that will be optimized away.
53  constexpr const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();
54  constexpr const char kLastDigitOfMaxUint64 =
55      '0' + static_cast<char>(kMaxUint64 % 10);
56
57  uint64_t value = 0;
58
59  // reinterpret_cast-ing from char* to uint8_t* to avoid signedness.
60  const uint8_t* start = reinterpret_cast<const uint8_t*>(in->data());
61
62  const uint8_t* end = start + in->size();
63  const uint8_t* current = start;
64  for (; current != end; ++current) {
65    const uint8_t ch = *current;
66    if (ch < '0' || ch > '9') break;
67
68    // Overflow check.
69    // kMaxUint64 / 10 is also constant and will be optimized away.
70    if (value > kMaxUint64 / 10 ||
71        (value == kMaxUint64 / 10 && ch > kLastDigitOfMaxUint64)) {
72      return false;
73    }
74
75    value = (value * 10) + (ch - '0');
76  }
77
78  *val = value;
79  const size_t digits_consumed = current - start;
80  in->remove_prefix(digits_consumed);
81  return digits_consumed != 0;
82}
83
84}  // namespace leveldb
85