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