Change stap parser to use an input file descriptor other than stdin

* grapher/StapParser.hxx (_inFd, getInFd, setInFd): new member and fuctions
* grapher/StapParser.cxx (ioCallback): Use _inFd variable
  instead of stdin.
* grapher/grapher.cxx (StapLauncher::launch): Don't read input from stap on
  stdin; use the the read end of the pipe.

3 files changed, 15 insertions, 16 deletions

diff --git a/grapher/StapParser.cxx b/grapher/StapParser.cxx
index 9bb9b9c9..eea85006 100644
--- a/grapher/StapParser.cxx
+++ b/grapher/StapParser.cxx
@@ -70,7 +70,7 @@ vector<string> commaSplit(const boost::sub_range<Glib::ustring>& range)
         return true;
       char buf[256];
       ssize_t bytes_read = 0;
-      bytes_read = read(STDIN_FILENO, buf, sizeof(buf) - 1);
+      bytes_read = read(_inFd, buf, sizeof(buf) - 1);
       if (bytes_read <= 0)
         {
           _win.hide();
diff --git a/grapher/StapParser.hxx b/grapher/StapParser.hxx
index f4f6bdef..eeebed63 100644
--- a/grapher/StapParser.hxx
+++ b/grapher/StapParser.hxx
@@ -13,14 +13,20 @@ class StapParser
   Gtk::Window& _win;
   GraphWidget& _widget;
   int _errFd;
+  int _inFd;
 public:
   StapParser(Gtk::Window& win,
-             GraphWidget& widget) : _win(win), _widget(widget), _errFd(-1) {}
+             GraphWidget& widget) : _win(win), _widget(widget), _errFd(-1),
+                                    _inFd(-1)
+  {
+  }
   void parseData(std::tr1::shared_ptr<GraphDataBase> gdata,
                  double time, const std::string& dataString);
   bool ioCallback(Glib::IOCondition ioCondition);
   bool errIoCallback(Glib::IOCondition ioCondition);
   int getErrFd() { return _errFd; }
   void setErrFd(int fd) { _errFd = fd; }
+  int getInFd() { return _inFd; }
+  void setInFd(int fd) { _inFd = fd; }
 };
 }
diff --git a/grapher/grapher.cxx b/grapher/grapher.cxx
index 429d0537..398b35f1 100644
--- a/grapher/grapher.cxx
+++ b/grapher/grapher.cxx
@@ -257,8 +257,6 @@ protected:
 
 int StapLauncher::launch()
 {
-  int stapErrFd = -1;
-
   if (pipe(&signalPipe[0]) < 0)
     {
       std::perror("pipe");
@@ -286,9 +284,6 @@ int StapLauncher::launch()
     }
   else if (_childPid)
     {
-      dup2(pipefd[0], STDIN_FILENO);
-      stapErrFd = pipefd[2];
-      close(pipefd[0]);
       close(pipefd[1]);
       close(pipefd[3]);
     }
@@ -318,14 +313,12 @@ int StapLauncher::launch()
         }
       _exit(1);
     }
-  if (stapErrFd >= 0)
-    {
-      _stapParser->setErrFd(stapErrFd);
-      Glib::signal_io().connect(sigc::mem_fun(*_stapParser,
-                                              &StapParser::errIoCallback),
-                                stapErrFd,
-                                Glib::IO_IN);
-    }
+  _stapParser->setErrFd(pipefd[2]);
+  _stapParser->setInFd(pipefd[0]);
+  Glib::signal_io().connect(sigc::mem_fun(*_stapParser,
+                                          &StapParser::errIoCallback),
+                            pipefd[2],
+                            Glib::IO_IN);
   setSigfd(signalPipe[0]);
   if (signalPipe[0] >= 0)
     {
@@ -335,7 +328,7 @@ int StapLauncher::launch()
     }
   Glib::signal_io().connect(sigc::mem_fun(*_stapParser,
                                           &StapParser::ioCallback),
-                            STDIN_FILENO,
+                            pipefd[0],
                             Glib::IO_IN | Glib::IO_HUP);
   return _childPid;
 }