85 lines
2.2 KiB
C++
85 lines
2.2 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "android-base/stringprintf.h"
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#include <stdio.h>
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#include <string>
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namespace android {
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namespace base {
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void StringAppendV(std::string* dst, const char* format, va_list ap) {
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// First try with a small fixed size buffer
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char space[1024];
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// It's possible for methods that use a va_list to invalidate
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// the data in it upon use. The fix is to make a copy
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// of the structure before using it and use that copy instead.
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va_list backup_ap;
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va_copy(backup_ap, ap);
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int result = vsnprintf(space, sizeof(space), format, backup_ap);
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va_end(backup_ap);
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if (result < static_cast<int>(sizeof(space))) {
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if (result >= 0) {
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// Normal case -- everything fit.
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dst->append(space, result);
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return;
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}
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if (result < 0) {
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// Just an error.
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return;
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}
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}
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// Increase the buffer size to the size requested by vsnprintf,
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// plus one for the closing \0.
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int length = result + 1;
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char* buf = new char[length];
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// Restore the va_list before we use it again
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va_copy(backup_ap, ap);
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result = vsnprintf(buf, length, format, backup_ap);
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va_end(backup_ap);
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if (result >= 0 && result < length) {
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// It fit
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dst->append(buf, result);
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}
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delete[] buf;
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}
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std::string StringPrintf(const char* fmt, ...) {
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va_list ap;
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va_start(ap, fmt);
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std::string result;
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StringAppendV(&result, fmt, ap);
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va_end(ap);
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return result;
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}
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void StringAppendF(std::string* dst, const char* format, ...) {
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va_list ap;
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va_start(ap, format);
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StringAppendV(dst, format, ap);
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va_end(ap);
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}
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} // namespace base
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} // namespace android
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