telnetd: Redirect stderr and stdin too

Previously, the Python telnet personality only handled stdout, so errors got lost and input would appear to hang (while it tried to read from the controlling terminal). Now we do all three.
kpengboy · Oct 13, 2013 · 0df91e2 · 0df91e2
1 parent fab63c6
commit 0df91e2
Showing 1 changed file with 23 additions and 0 deletions.
diff --git a/pox/misc/telnetd/__init__.py b/pox/misc/telnetd/__init__.py
@@ -1658,9 +1658,30 @@ def _handle_line (self, line):
 
     # Won't necessarily play nice with multiple threads!
     import sys
+
+    # Redirect standard IO to the telnet session.  May not play nicely
+    # with multiple threads.
+    # Note that we also set stdin to an empty StringIO.  This is because
+    # otherwise doing something that tried to read would try to read from
+    # the controlling terminal, which isn't what we want at all.  So this
+    # effectively disables input.  I think the only way we could add it in
+    # would be to run the Python code in a separate thread (blocking the
+    # cooperative one except during input).  I've actually been thinking
+    # about doing this for the "py" module for a long time (so that code
+    # from the CLI runs in the cooperative context), but haven't ever
+    # gotten around to it.  Note that this doesn't appear to work in PyPy,
+    # but I haven't looked into why yet.
+
     oldout = sys.stdout
+    olderr = sys.stderr
+    oldin = sys.stdin
     from StringIO import StringIO
     sys.stdout = StringIO()
+    sys.stderr = sys.stdout
+    # Sometime in the future something like this may be more useful...
+    #sys.stdout.write = self.send
+    #sys.stderr.write = self.send
+    sys.stdin = StringIO()
     try:
       self.interp.runcode(o)
       r = sys.stdout.getvalue()
@@ -1673,6 +1694,8 @@ def _handle_line (self, line):
       return
     finally:
       sys.stdout = oldout
+      sys.stderr = olderr
+      sys.stdin = oldin
 
     self.send("POX> ")