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/*
* Copyright (C) 2011 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/stringprintf.h"
#include <stdio.h>
#include <string>
namespace android {
namespace base {
void StringAppendV(std::string* dst, const char* format, va_list ap) {
// First try with a small fixed size buffer
char space[1024];
// It's possible for methods that use a va_list to invalidate
// the data in it upon use. The fix is to make a copy
// of the structure before using it and use that copy instead.
va_list backup_ap;
va_copy(backup_ap, ap);
int result = vsnprintf(space, sizeof(space), format, backup_ap);
va_end(backup_ap);
if (result < static_cast<int>(sizeof(space))) {
if (result >= 0) {
// Normal case -- everything fit.
dst->append(space, result);
return;
}
if (result < 0) {
// Just an error.
return;
}
}
// Increase the buffer size to the size requested by vsnprintf,
// plus one for the closing \0.
int length = result + 1;
char* buf = new char[length];
// Restore the va_list before we use it again
va_copy(backup_ap, ap);
result = vsnprintf(buf, length, format, backup_ap);
va_end(backup_ap);
if (result >= 0 && result < length) {
// It fit
dst->append(buf, result);
}
delete[] buf;
}
std::string StringPrintf(const char* fmt, ...) {
va_list ap;
va_start(ap, fmt);
std::string result;
StringAppendV(&result, fmt, ap);
va_end(ap);
return result;
}
void StringAppendF(std::string* dst, const char* format, ...) {
va_list ap;
va_start(ap, format);
StringAppendV(dst, format, ap);
va_end(ap);
}
} // namespace base
} // namespace android
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