-// ----------------------------------------------------------------------------
-// wxStreamTempInputBuffer
-// ----------------------------------------------------------------------------
-
-/*
- 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 4Kb) 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 (wxStreamTempInputBuffer object) and later just stuff it back into the
- stream when the process terminates. See supporting code in wxExecute()
- itself as well.
-
- Note that this is horribly inefficient for large amounts of output (count
- the number of times we copy the data around) and so a better API is badly
- needed!
-*/
-
-class wxStreamTempInputBuffer
-{
-public:
- wxStreamTempInputBuffer();
-
- // call to associate a stream with this buffer, otherwise nothing happens
- // at all
- void Init(wxProcessFileInputStream *stream);
-
- // check for input on our stream and cache it in our buffer if any
- void Update();
-
- ~wxStreamTempInputBuffer();
-
-private:
- // the stream we're buffering, if NULL we don't do anything at all
- wxProcessFileInputStream *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;
-};
-
-wxStreamTempInputBuffer::wxStreamTempInputBuffer()
-{
- m_stream = NULL;
- m_buffer = NULL;
- m_size = 0;
-}
-
-void wxStreamTempInputBuffer::Init(wxProcessFileInputStream *stream)
-{
- m_stream = stream;
-}
-
-void wxStreamTempInputBuffer::Update()
-{
- if ( m_stream && m_stream->IsAvailable() )
- {
- // realloc in blocks of 4Kb: this is the default (and minimal) buffer
- // size of the Unix pipes so it should be the optimal step
- static const size_t incSize = 4096;
-
- 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 += m_stream->LastRead();
- }
- }
-}
-
-wxStreamTempInputBuffer::~wxStreamTempInputBuffer()
-{
- if ( m_buffer )
- {
- m_stream->Ungetch(m_buffer, m_size);
- free(m_buffer);
- }
-}
-
-#endif // wxUSE_STREAMS
-
-// ----------------------------------------------------------------------------
-// wxPipe: this encapsulates pipe() system call
-// ----------------------------------------------------------------------------
-
-class wxPipe
-{
-public:
- // the symbolic names for the pipe ends
- enum Direction
- {
- Read,
- Write
- };
-
- enum
- {
- INVALID_FD = -1
- };
-
- // default ctor doesn't do anything
- wxPipe() { m_fds[Read] = m_fds[Write] = INVALID_FD; }
-
- // create the pipe, return TRUE if ok, FALSE on error
- bool Create()
- {
- if ( pipe(m_fds) == -1 )
- {
- wxLogSysError(_("Pipe creation failed"));
-
- return FALSE;
- }
-
- return TRUE;
- }
-
- // return TRUE if we were created successfully
- bool IsOk() const { return m_fds[Read] != INVALID_FD; }
-
- // return the descriptor for one of the pipe ends
- int operator[](Direction which) const
- {
- wxASSERT_MSG( which >= 0 && (size_t)which < WXSIZEOF(m_fds),
- _T("invalid pipe index") );
-
- return m_fds[which];
- }
-
- // detach a descriptor, meaning that the pipe dtor won't close it, and
- // return it
- int Detach(Direction which)
- {
- wxASSERT_MSG( which >= 0 && (size_t)which < WXSIZEOF(m_fds),
- _T("invalid pipe index") );
-
- int fd = m_fds[which];
- m_fds[which] = INVALID_FD;
-
- return fd;
- }
-
- // close the pipe descriptors
- void Close()
- {
- for ( size_t n = 0; n < WXSIZEOF(m_fds); n++ )
- {
- if ( m_fds[n] != INVALID_FD )
- close(m_fds[n]);
- }
- }
-
- // dtor closes the pipe descriptors
- ~wxPipe() { Close(); }
-
-private:
- int m_fds[2];
-};
projects / wxWidgets.git / blobdiff