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 <cstdarg> |
8 | #include <cstdio> |
9 | #include <cstdlib> |
10 | #include <limits> |
11 | |
12 | #include "leveldb/env.h" |
13 | #include "leveldb/slice.h" |
14 | |
15 | namespace leveldb { |
16 | |
17 | void AppendNumberTo(std::string* str, uint64_t num) { |
18 | char buf[30]; |
19 | std::snprintf(buf, sizeof(buf), "%llu" , static_cast<unsigned long long>(num)); |
20 | str->append(buf); |
21 | } |
22 | |
23 | void AppendEscapedStringTo(std::string* str, const Slice& value) { |
24 | for (size_t i = 0; i < value.size(); i++) { |
25 | char c = value[i]; |
26 | if (c >= ' ' && c <= '~') { |
27 | str->push_back(c); |
28 | } else { |
29 | char buf[10]; |
30 | std::snprintf(buf, sizeof(buf), "\\x%02x" , |
31 | static_cast<unsigned int>(c) & 0xff); |
32 | str->append(buf); |
33 | } |
34 | } |
35 | } |
36 | |
37 | std::string NumberToString(uint64_t num) { |
38 | std::string r; |
39 | AppendNumberTo(&r, num); |
40 | return r; |
41 | } |
42 | |
43 | std::string EscapeString(const Slice& value) { |
44 | std::string r; |
45 | AppendEscapedStringTo(&r, value); |
46 | return r; |
47 | } |
48 | |
49 | bool ConsumeDecimalNumber(Slice* in, uint64_t* val) { |
50 | // Constants that will be optimized away. |
51 | constexpr const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max(); |
52 | constexpr const char kLastDigitOfMaxUint64 = |
53 | '0' + static_cast<char>(kMaxUint64 % 10); |
54 | |
55 | uint64_t value = 0; |
56 | |
57 | // reinterpret_cast-ing from char* to uint8_t* to avoid signedness. |
58 | const uint8_t* start = reinterpret_cast<const uint8_t*>(in->data()); |
59 | |
60 | const uint8_t* end = start + in->size(); |
61 | const uint8_t* current = start; |
62 | for (; current != end; ++current) { |
63 | const uint8_t ch = *current; |
64 | if (ch < '0' || ch > '9') break; |
65 | |
66 | // Overflow check. |
67 | // kMaxUint64 / 10 is also constant and will be optimized away. |
68 | if (value > kMaxUint64 / 10 || |
69 | (value == kMaxUint64 / 10 && ch > kLastDigitOfMaxUint64)) { |
70 | return false; |
71 | } |
72 | |
73 | value = (value * 10) + (ch - '0'); |
74 | } |
75 | |
76 | *val = value; |
77 | const size_t digits_consumed = current - start; |
78 | in->remove_prefix(digits_consumed); |
79 | return digits_consumed != 0; |
80 | } |
81 | |
82 | } // namespace leveldb |
83 | |