1//
2// StreamUtil.h
3//
4// Library: Foundation
5// Package: Streams
6// Module: StreamUtil
7//
8// Stream implementation support.
9//
10// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
11// and Contributors.
12//
13// SPDX-License-Identifier: BSL-1.0
14//
15
16
17#ifndef Foundation_StreamUtil_INCLUDED
18#define Foundation_StreamUtil_INCLUDED
19
20
21#include "Poco/Foundation.h"
22
23
24// poco_ios_init
25//
26// This is a workaround for a bug in the Dinkumware
27// implementation of iostreams.
28//
29// Calling basic_ios::init() multiple times for the
30// same basic_ios instance results in a memory leak
31// caused by the ios' locale being allocated more than
32// once, each time overwriting the old pointer.
33// This usually occurs in the following scenario:
34//
35// class MyStreamBuf: public std::streambuf
36// {
37// ...
38// };
39//
40// class MyIOS: public virtual std::ios
41// {
42// public:
43// MyIOS()
44// {
45// init(&_buf);
46// }
47// protected:
48// MyStreamBuf _buf;
49// };
50//
51// class MyIStream: public MyIOS, public std::istream
52// {
53// ...
54// };
55//
56// In this scenario, std::ios::init() is called twice
57// (the first time by the MyIOS constructor, the second
58// time by the std::istream constructor), resulting in
59// two locale objects being allocated, the pointer second
60// one overwriting the pointer to the first one and thus
61// causing a memory leak.
62//
63// The workaround is to call init() only once for each
64// stream object - by the istream, ostream or iostream
65// constructor, and not calling init() in ios-derived
66// base classes.
67//
68// Some stream implementations, however, require that
69// init() is called in the MyIOS constructor.
70// Therefore we replace each call to init() with
71// the poco_ios_init macro defined below.
72
73
74#if !defined(POCO_IOS_INIT_HACK)
75 // Microsoft Visual Studio with Dinkumware STL (but not STLport)
76# if defined(_MSC_VER) && (!defined(_STLP_MSVC) || defined(_STLP_NO_OWN_IOSTREAMS))
77# define POCO_IOS_INIT_HACK 1
78 // QNX with Dinkumware but not GNU C++ Library
79# elif defined(__QNX__) && !defined(__GLIBCPP__)
80# define POCO_IOS_INIT_HACK 1
81# endif
82#endif
83
84
85#if defined(POCO_IOS_INIT_HACK)
86# define poco_ios_init(buf)
87#else
88# define poco_ios_init(buf) init(buf)
89#endif
90
91
92#endif // Foundation_StreamUtil_INCLUDED
93