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// Copyright (C) 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "icing/legacy/core/icing-string-util.h"
#include <algorithm>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <string>
#include "icing/legacy/portable/icing-zlib.h"
#include "icing/util/logging.h"
namespace icing {
namespace lib {
uint32_t IcingStringUtil::UpdateCrc32(uint32_t crc, const char *str, int len) {
if (len > 0) {
crc = ~crc32(~crc, reinterpret_cast<const Bytef *>(str), len);
}
return crc;
}
uint32_t IcingStringUtil::UpdateAtPositionCrc32(uint32_t crc, int orig_len,
int offset,
const char *xored_str,
int len) {
// For appending, use UpdateCrc32.
if (offset + len > orig_len) {
ICING_LOG(FATAL) << "offset: " << offset << " length: " << len
<< "original_length: " << orig_len;
}
// We have CRC(A|U|B) and we want CRC(A|V|B) where U is the slice
// that updated to V.
//
// Then if xored_str = X = U ^ V:
//
// CRC(A|V|B) = CRC(0_lenA|X|0_lenB ^ A|U|B)
// = CRC(0_lenA|X|0_lenB) ^ CRC(A|U|B)
// = CRC_COMBINE(CRC(0_lenA), CRC_COMBINE(CRC(X), CRC(0_lenB)) ^ CRC(A|U|B)
//
// But CRC(0s) = 0, and CRC_COMBINE(0, X) = X, so this becomes
// = CRC_COMBINE(CRC(X), CRC(0_lenB)) ^ CRC(A|U|B)
uint32_t update_crc = UpdateCrc32(0, xored_str, len);
update_crc = crc32_combine(update_crc, 0, orig_len - (offset + len));
return crc ^ update_crc;
}
void IcingStringUtil::SStringAppendV(std::string *strp, int bufsize,
const char *fmt, va_list arglist) {
int capacity = bufsize;
if (capacity <= 0) {
va_list backup;
va_copy(backup, arglist);
capacity = vsnprintf(nullptr, 0, fmt, backup);
va_end(arglist);
}
size_t start = strp->size();
strp->resize(strp->size() + capacity + 1);
int written = vsnprintf(&(*strp)[start], capacity + 1, fmt, arglist);
va_end(arglist);
strp->resize(start + std::min(capacity, written));
}
void IcingStringUtil::SStringAppendF(std::string *strp, int bufsize,
const char *fmt, ...) {
va_list arglist;
va_start(arglist, fmt);
SStringAppendV(strp, bufsize, fmt, arglist);
}
std::string IcingStringUtil::StringPrintf(const char *fmt, ...) {
std::string s;
va_list arglist;
va_start(arglist, fmt);
SStringAppendV(&s, 0, fmt, arglist);
return s;
}
} // namespace lib
} // namespace icing
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