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// Copyright 2014 The Android Open Source Project
//
// 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 "android/base/StringFormat.h"
#include <stdio.h>
namespace android {
namespace base {
std::string StringFormatRaw(const char* format, ...) {
va_list args;
va_start(args, format);
auto result = StringFormatWithArgs(format, args);
va_end(args);
return result;
}
std::string StringFormatWithArgs(const char* format, va_list args) {
std::string result;
StringAppendFormatWithArgs(&result, format, args);
return result;
}
void StringAppendFormatRaw(std::string* string, const char* format, ...) {
va_list args;
va_start(args, format);
StringAppendFormatWithArgs(string, format, args);
va_end(args);
}
void StringAppendFormatWithArgs(std::string* string,
const char* format,
va_list args) {
size_t cur_size = string->size();
size_t extra = 0;
for (;;) {
va_list args2;
va_copy(args2, args);
int ret = vsnprintf(&(*string)[cur_size], extra, format, args2);
va_end(args2);
if (ret == 0) {
// Nothing to do here.
break;
}
if (ret > 0) {
size_t ret_sz = static_cast<size_t>(ret);
if (extra == 0) {
// First pass, resize the string and try again.
extra = ret_sz + 1;
string->resize(cur_size + extra);
continue;
}
if (ret_sz < extra) {
// Second pass or later, success!
string->resize(cur_size + ret_sz);
return;
}
}
// NOTE: The MSVCRT.DLL implementation of snprintf() is broken and
// will return -1 in case of truncation. This code path is taken
// when this happens, or when |ret_sz| is equal or larger than
// |extra|. Grow the buffer to allow for more room, then try again.
extra += (extra >> 1) + 32;
string->resize(cur_size + extra);
}
}
} // namespace base
} // namespace android