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
+ 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 (wxStreamTempBuffer object) and later just stuff it back into the
stream when the process terminates. See supporting code in wxExecute()
- itself as well.
+ 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 wxStreamTempBuffer
wxStreamTempBuffer::wxStreamTempBuffer()
{
- m_stream = NULL;
+ m_stream = NULL;
m_buffer = NULL;
m_size = 0;
}
{
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;
+ // 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 )
{
m_buffer = buf;
m_stream->Read((char *)m_buffer + m_size, incSize);
- m_size += incSize;
+ m_size += m_stream->LastRead();
}
}
}
#endif // wxUSE_STREAMS
+// ----------------------------------------------------------------------------
+// wxPipe: this encpasulates 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];
+};
+
+// ----------------------------------------------------------------------------
+// wxExecute: the real worker function
+// ----------------------------------------------------------------------------
+
long wxExecute(wxChar **argv,
int flags,
wxProcess *process)
#if wxUSE_GUI
// create pipes
- int end_proc_detect[2];
- if ( pipe(end_proc_detect) == -1 )
+ wxPipe pipeEndProcDetect;
+ if ( !pipeEndProcDetect.Create() )
{
- wxLogSysError( _("Pipe creation failed") );
wxLogError( _("Failed to execute '%s'\n"), *argv );
ARGS_CLEANUP;
#endif // wxUSE_GUI
// pipes for inter process communication
- int pipeIn[2], // stdin
- pipeOut[2], // stdout
- pipeErr[2]; // stderr
-
- pipeIn[0] = pipeIn[1] =
- pipeOut[0] = pipeOut[1] =
- pipeErr[0] = pipeErr[1] = -1;
+ wxPipe pipeIn, // stdin
+ pipeOut, // stdout
+ pipeErr; // stderr
if ( process && process->IsRedirected() )
{
- if ( pipe(pipeIn) == -1 || pipe(pipeOut) == -1 || pipe(pipeErr) == -1 )
+ if ( !pipeIn.Create() || !pipeOut.Create() || !pipeErr.Create() )
{
-#if wxUSE_GUI
- // free previously allocated resources
- close(end_proc_detect[0]);
- close(end_proc_detect[1]);
-#endif // wxUSE_GUI
-
- wxLogSysError( _("Pipe creation failed") );
wxLogError( _("Failed to execute '%s'\n"), *argv );
ARGS_CLEANUP;
if ( pid == -1 ) // error?
{
-#if wxUSE_GUI
- close(end_proc_detect[0]);
- close(end_proc_detect[1]);
- close(pipeIn[0]);
- close(pipeIn[1]);
- close(pipeOut[0]);
- close(pipeOut[1]);
- close(pipeErr[0]);
- close(pipeErr[1]);
-#endif // wxUSE_GUI
-
wxLogSysError( _("Fork failed") );
ARGS_CLEANUP;
else if ( pid == 0 ) // we're in child
{
#if wxUSE_GUI
- close(end_proc_detect[0]); // close reading side
+ // reading side can be safely closed but we should keep the write one
+ // opened
+ pipeEndProcDetect.Detach(wxPipe::Write);
#endif // wxUSE_GUI
// These lines close the open file descriptors to to avoid any
{
for ( int fd = 0; fd < FD_SETSIZE; fd++ )
{
- if ( fd == pipeIn[0] || fd == pipeOut[1] || fd == pipeErr[1]
+ if ( fd == pipeIn[wxPipe::Read]
+ || fd == pipeOut[wxPipe::Write]
+ || fd == pipeErr[wxPipe::Write]
#if wxUSE_GUI
- || fd == end_proc_detect[1]
+ || fd == pipeEndProcDetect[wxPipe::Write]
#endif // wxUSE_GUI
)
{
continue;
}
- // leave stderr opened too, it won't do any hurm
+ // leave stderr opened too, it won't do any harm
if ( fd != STDERR_FILENO )
close(fd);
}
#ifndef __VMS
- if ( flags & wxEXEC_MAKE_GROUP_LEADER )
+ if ( flags & wxEXEC_MAKE_GROUP_LEADER )
{
// Set process group to child process' pid. Then killing -pid
// of the parent will kill the process and all of its children.
setsid();
}
-#endif
+#endif // !__VMS
}
// redirect stdio, stdout and stderr
- if ( pipeIn[0] != -1 )
+ if ( pipeIn.IsOk() )
{
- if ( dup2(pipeIn[0], STDIN_FILENO) == -1 ||
- dup2(pipeOut[1], STDOUT_FILENO) == -1 ||
- dup2(pipeErr[1], STDERR_FILENO) == -1 )
+ if ( dup2(pipeIn[wxPipe::Read], STDIN_FILENO) == -1 ||
+ dup2(pipeOut[wxPipe::Write], STDOUT_FILENO) == -1 ||
+ dup2(pipeErr[wxPipe::Write], STDERR_FILENO) == -1 )
{
wxLogSysError(_("Failed to redirect child process input/output"));
}
- close(pipeIn[0]);
- close(pipeOut[1]);
- close(pipeErr[1]);
+ pipeIn.Close();
+ pipeOut.Close();
+ pipeErr.Close();
}
execvp (*mb_argv, mb_argv);
// some compilers complain about missing return - of course, they
// should know that exit() doesn't return but what else can we do if
// they don't?
+ //
+ // and, sure enough, other compilers complain about unreachable code
+ // after exit() call, so we can just always have return here...
#if defined(__VMS) || defined(__INTEL_COMPILER)
return 0;
#endif
{
#if wxUSE_STREAMS
// in/out for subprocess correspond to our out/in
- wxOutputStream *outStream = new wxProcessFileOutputStream(pipeIn[1]);
- wxInputStream *inStream = new wxProcessFileInputStream(pipeOut[0]);
- wxInputStream *errStream = new wxProcessFileInputStream(pipeErr[0]);
+ wxOutputStream *outStream =
+ new wxProcessFileOutputStream(pipeIn.Detach(wxPipe::Write));
+
+ wxInputStream *inStream =
+ new wxProcessFileInputStream(pipeOut.Detach(wxPipe::Read));
+
+ wxInputStream *errStream =
+ new wxProcessFileInputStream(pipeErr.Detach(wxPipe::Read));
process->SetPipeStreams(inStream, outStream, errStream);
bufIn.Init(inStream);
- bufErr.Init(inStream);
+ bufErr.Init(errStream);
#endif // wxUSE_STREAMS
+ }
- close(pipeIn[0]); // close reading side
- close(pipeOut[1]); // close writing side
- close(pipeErr[1]); // close writing side
+ if ( pipeIn.IsOk() )
+ {
+ pipeIn.Close();
+ pipeOut.Close();
+ pipeErr.Close();
}
#if wxUSE_GUI && !defined(__WXMICROWIN__)
wxEndProcessData *data = new wxEndProcessData;
+ data->tag = wxAddProcessCallback
+ (
+ data,
+ pipeEndProcDetect.Detach(wxPipe::Read)
+ );
+
+ pipeEndProcDetect.Close();
+
if ( flags & wxEXEC_SYNC )
{
// we may have process for capturing the program output, but it's
// sync execution: indicate it by negating the pid
data->pid = -pid;
- data->tag = wxAddProcessCallback(data, end_proc_detect[0]);
-
- close(end_proc_detect[1]); // close writing side
wxBusyCursor bc;
wxWindowDisabler wd;
// will be deleted in GTK_EndProcessDetector
data->process = process;
data->pid = pid;
- data->tag = wxAddProcessCallback(data, end_proc_detect[0]);
-
- close(end_proc_detect[1]); // close writing side
return pid;
}
projects / wxWidgets.git / commitdiff
