mirror of https://github.com/PCSX2/pcsx2.git
135 lines
4.3 KiB
C++
135 lines
4.3 KiB
C++
///////////////////////////////////////////////////////////////////////////////
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// Name: wx/private/streamtempinput.h
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// Purpose: defines wxStreamTempInputBuffer which is used by Unix and MSW
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// implementations of wxExecute; this file is only used by the
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// library and never by the user code
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// Author: Vadim Zeitlin
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// Modified by: Rob Bresalier
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// Created: 2013-05-04
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// Copyright: (c) 2002 Vadim Zeitlin <vadim@wxwindows.org>
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// Licence: wxWindows licence
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///////////////////////////////////////////////////////////////////////////////
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#ifndef _WX_PRIVATE_STREAMTEMPINPUT_H
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#define _WX_PRIVATE_STREAMTEMPINPUT_H
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#include "wx/private/pipestream.h"
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// ----------------------------------------------------------------------------
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// wxStreamTempInputBuffer
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// ----------------------------------------------------------------------------
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/*
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wxStreamTempInputBuffer is a hack which we need to solve the problem of
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executing a child process synchronously with IO redirecting: when we do
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this, the child writes to a pipe we open to it but when the pipe buffer
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(which has finite capacity, e.g. commonly just 4Kb) becomes full we have to
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read data from it because the child blocks in its write() until then and if
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it blocks we are never going to return from wxExecute() so we dead lock.
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So here is the fix: we now read the output as soon as it appears into a temp
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buffer (wxStreamTempInputBuffer object) and later just stuff it back into
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the stream when the process terminates. See supporting code in wxExecute()
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itself as well.
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Note that this is horribly inefficient for large amounts of output (count
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the number of times we copy the data around) and so a better API is badly
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needed! However it's not easy to devise a way to do this keeping backwards
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compatibility with the existing wxExecute(wxEXEC_SYNC)...
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*/
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class wxStreamTempInputBuffer
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{
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public:
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wxStreamTempInputBuffer()
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{
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m_stream = NULL;
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m_buffer = NULL;
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m_size = 0;
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}
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// call to associate a stream with this buffer, otherwise nothing happens
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// at all
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void Init(wxPipeInputStream *stream)
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{
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wxASSERT_MSG( !m_stream, wxS("Can only initialize once") );
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m_stream = stream;
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}
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// check for input on our stream and cache it in our buffer if any
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//
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// return true if anything was done
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bool Update()
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{
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if ( !m_stream || !m_stream->CanRead() )
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return false;
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// realloc in blocks of 4Kb: this is the default (and minimal) buffer
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// size of the Unix pipes so it should be the optimal step
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//
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// NB: don't use "static int" in this inline function, some compilers
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// (e.g. IBM xlC) don't like it
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enum { incSize = 4096 };
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void *buf = realloc(m_buffer, m_size + incSize);
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if ( !buf )
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return false;
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m_buffer = buf;
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m_stream->Read((char *)m_buffer + m_size, incSize);
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m_size += m_stream->LastRead();
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return true;
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}
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// check if can continue reading from the stream, this is used to disable
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// the callback once we can't read anything more
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bool Eof() const
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{
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// If we have no stream, always return true as we can't read any more.
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return !m_stream || m_stream->Eof();
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}
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// read everything remaining until the EOF, this should only be called once
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// the child process terminates and we know that no more data is coming
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bool ReadAll()
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{
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while ( !Eof() )
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{
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if ( !Update() )
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return false;
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}
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return true;
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}
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// dtor puts the data buffered during this object lifetime into the
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// associated stream
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~wxStreamTempInputBuffer()
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{
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if ( m_buffer )
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{
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m_stream->Ungetch(m_buffer, m_size);
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free(m_buffer);
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}
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}
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const void *GetBuffer() const { return m_buffer; }
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size_t GetSize() const { return m_size; }
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private:
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// the stream we're buffering, if NULL we don't do anything at all
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wxPipeInputStream *m_stream;
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// the buffer of size m_size (NULL if m_size == 0)
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void *m_buffer;
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// the size of the buffer
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size_t m_size;
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wxDECLARE_NO_COPY_CLASS(wxStreamTempInputBuffer);
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};
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#endif // _WX_PRIVATE_STREAMTEMPINPUT_H
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