- // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file. See the AUTHORS file for names of contributors.
-
- #include "util/logging.h"
-
- #include <errno.h>
- #include <stdarg.h>
- #include <stdio.h>
- #include <stdlib.h>
-
- #include <limits>
-
- #include "leveldb/env.h"
- #include "leveldb/slice.h"
-
- namespace leveldb {
-
- void AppendNumberTo(std::string* str, uint64_t num) {
- char buf[30];
- snprintf(buf, sizeof(buf), "%llu", (unsigned long long)num);
- str->append(buf);
- }
-
- void AppendEscapedStringTo(std::string* str, const Slice& value) {
- for (size_t i = 0; i < value.size(); i++) {
- char c = value[i];
- if (c >= ' ' && c <= '~') {
- str->push_back(c);
- } else {
- char buf[10];
- snprintf(buf, sizeof(buf), "\\x%02x",
- static_cast<unsigned int>(c) & 0xff);
- str->append(buf);
- }
- }
- }
-
- std::string NumberToString(uint64_t num) {
- std::string r;
- AppendNumberTo(&r, num);
- return r;
- }
-
- std::string EscapeString(const Slice& value) {
- std::string r;
- AppendEscapedStringTo(&r, value);
- return r;
- }
-
- bool ConsumeDecimalNumber(Slice* in, uint64_t* val) {
- // Constants that will be optimized away.
- constexpr const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();
- constexpr const char kLastDigitOfMaxUint64 =
- '0' + static_cast<char>(kMaxUint64 % 10);
-
- uint64_t value = 0;
-
- // reinterpret_cast-ing from char* to uint8_t* to avoid signedness.
- const uint8_t* start = reinterpret_cast<const uint8_t*>(in->data());
-
- const uint8_t* end = start + in->size();
- const uint8_t* current = start;
- for (; current != end; ++current) {
- const uint8_t ch = *current;
- if (ch < '0' || ch > '9') break;
-
- // Overflow check.
- // kMaxUint64 / 10 is also constant and will be optimized away.
- if (value > kMaxUint64 / 10 ||
- (value == kMaxUint64 / 10 && ch > kLastDigitOfMaxUint64)) {
- return false;
- }
-
- value = (value * 10) + (ch - '0');
- }
-
- *val = value;
- const size_t digits_consumed = current - start;
- in->remove_prefix(digits_consumed);
- return digits_consumed != 0;
- }
-
- } // namespace leveldb
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