-/*
- Extract of a mail to wx-users to give the context of the problem we are
- trying to solve here:
-
- MC> If I run the command:
- MC> find . -name "*.h" -exec grep linux {} \;
- MC> in the exec sample synchronously from the 'Capture command output'
- MC> menu, wxExecute never returns. I have to xkill it. Has anyone
- MC> else encountered this?
-
- Yes, I can reproduce it too.
-
- I even think I understand why it happens: before launching the external
- command we set up a pipe with a valid file descriptor on the reading side
- when the output is redirected. So the subprocess happily writes to it ...
- until the pipe buffer (which is usually quite big on Unix, I think the
- default is 4Mb) is full. Then the writing process stops and waits until we
- read some data from the pipe to be able to continue writing to it but we
- never do it because we wait until it terminates to start reading and so we
- have a classical deadlock.
-
- Here is the fix: we now read the output as soon as it appears into a temp
- buffer (wxStreamTempBuffer object) and later just stuff it back into the
- stream when the process terminates. See supporting code in wxExecute()
- itself as well.
-*/
-
-class wxStreamTempBuffer
-{
-public:
- wxStreamTempBuffer();
-
- // call to associate a stream with this buffer, otherwise nothing happens
- // at all
- void Init(wxInputStream *stream);
-
- // check for input on our stream and cache it in our buffer if any
- void Update();
-
- ~wxStreamTempBuffer();
-
-private:
- // the stream we're buffering, if NULL we don't do anything at all
- wxInputStream *m_stream;
-
- // the buffer of size m_size (NULL if m_size == 0)
- void *m_buffer;
-
- // the size of the buffer
- size_t m_size;
-};
-
-wxStreamTempBuffer::wxStreamTempBuffer()
-{
- m_stream = NULL;
- m_buffer = NULL;
- m_size = 0;
-}
-
-void wxStreamTempBuffer::Init(wxInputStream *stream)
-{
- m_stream = stream;
-}
-
-void wxStreamTempBuffer::Update()
-{
- if ( m_stream && !m_stream->Eof() )
- {
- // realloc in blocks of 1Kb - surely not the best strategy but which
- // one is?
- static const size_t incSize = 1024;
-
- void *buf = realloc(m_buffer, m_size + incSize);
- if ( !buf )
- {
- // don't read any more, we don't have enough memory to do it
- m_stream = NULL;
- }
- else // got memory for the buffer
- {
- m_buffer = buf;
- m_stream->Read((char *)m_buffer + m_size, incSize);
- m_size += incSize;
- }
- }
-}
-
-wxStreamTempBuffer::~wxStreamTempBuffer()
-{
- if ( m_buffer )
- {
- m_stream->Ungetch(m_buffer, m_size);
- free(m_buffer);
- }
-}
-
-#endif // wxUSE_STREAMS
-
-long wxExecute(wxChar **argv,
- bool sync,
- wxProcess *process)
projects / wxWidgets.git / blobdiff