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// 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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