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93 lines
2.3 KiB
C++
93 lines
2.3 KiB
C++
//
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// StreamUtil.h
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//
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// Library: Foundation
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// Package: Streams
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// Module: StreamUtil
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//
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// Stream implementation support.
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//
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// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_StreamUtil_INCLUDED
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#define Foundation_StreamUtil_INCLUDED
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#include "Poco/Foundation.h"
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// poco_ios_init
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//
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// This is a workaround for a bug in the Dinkumware
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// implementation of iostreams.
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//
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// Calling basic_ios::init() multiple times for the
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// same basic_ios instance results in a memory leak
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// caused by the ios' locale being allocated more than
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// once, each time overwriting the old pointer.
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// This usually occurs in the following scenario:
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//
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// class MyStreamBuf: public std::streambuf
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// {
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// ...
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// };
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//
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// class MyIOS: public virtual std::ios
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// {
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// public:
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// MyIOS()
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// {
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// init(&_buf);
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// }
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// protected:
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// MyStreamBuf _buf;
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// };
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//
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// class MyIStream: public MyIOS, public std::istream
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// {
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// ...
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// };
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//
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// In this scenario, std::ios::init() is called twice
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// (the first time by the MyIOS constructor, the second
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// time by the std::istream constructor), resulting in
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// two locale objects being allocated, the pointer second
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// one overwriting the pointer to the first one and thus
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// causing a memory leak.
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//
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// The workaround is to call init() only once for each
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// stream object - by the istream, ostream or iostream
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// constructor, and not calling init() in ios-derived
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// base classes.
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//
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// Some stream implementations, however, require that
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// init() is called in the MyIOS constructor.
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// Therefore we replace each call to init() with
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// the poco_ios_init macro defined below.
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//
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// Also this macro will adjust exceptions() flags, since by default std::ios
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// will hide exceptions, while in ClickHouse it is better to pass them through.
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#if !defined(POCO_IOS_INIT_HACK)
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// Microsoft Visual Studio with Dinkumware STL (but not STLport)
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#endif
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#if defined(POCO_IOS_INIT_HACK)
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# define poco_ios_init(buf)
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#else
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# define poco_ios_init(buf) do { \
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init(buf); \
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this->exceptions(std::ios::failbit | std::ios::badbit); \
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} while (0)
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#endif
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#endif // Foundation_StreamUtil_INCLUDED
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