Merge branch 'i473'

IPython/utils/rlineimpl.py

@@ -1,86 +1,95
 # -*- coding: utf-8 -*-
 """ Imports and provides the 'correct' version of readline for the platform.
 
 Readline is used throughout IPython as::
 
     import IPython.utils.rlineimpl as readline
 
 In addition to normal readline stuff, this module provides have_readline
 boolean and _outputfile variable used in IPython.utils.
 """
 
+import re
 import sys
+import time
 import warnings
 
+from subprocess import Popen, PIPE
+
 try:
     from readline import *
     import readline as _rl
     have_readline = True
 except ImportError:
     try:
         from pyreadline import *
         import pyreadline as _rl
         have_readline = True
     except ImportError:
         have_readline = False
 
 if have_readline and hasattr(_rl, 'rlmain'):
     # patch add_history to allow for strings in pyreadline <= 1.5:
     # fix copied from pyreadline 1.6
     import pyreadline
     if pyreadline.release.version <= '1.5':
         def add_history(line):
             """add a line to the history buffer."""
             from pyreadline import lineobj
             if not isinstance(line, lineobj.TextLine):
                 line = lineobj.TextLine(line)
             return _rl.add_history(line)
 
 if sys.platform == 'win32' and have_readline:
     try:
         _outputfile=_rl.GetOutputFile()
     except AttributeError:
         print "Failed GetOutputFile"
         have_readline = False
 
 # Test to see if libedit is being used instead of GNU readline.
-# Thanks to Boyd Waters for this patch.
+# Thanks to Boyd Waters for the original patch.
 uses_libedit = False
 if sys.platform == 'darwin' and have_readline:
-    import commands
-    # Boyd's patch had a 'while True' here, I'm always a little worried about
-    # infinite loops with such code, so for now I'm taking a more conservative
-    # approach. See https://bugs.launchpad.net/ipython/+bug/411599.
-    for i in range(10):
-        try:
-            (status, result) = commands.getstatusoutput( "otool -L %s | grep libedit" % _rl.__file__ )
-            break
-        except IOError, (errno, strerror):
-            if errno == 4:
+    # Previously this used commands.getstatusoutput, which uses os.popen.
+    # Switching to subprocess.Popen, and exponential falloff for EINTR
+    # seems to make this better behaved in environments such as PyQt and gdb
+    dt = 1e-3
+    while dt < 1:
+        p = Popen(['otool', '-L', _rl.__file__], stdout=PIPE, stderr=PIPE)
+        otool,err = p.communicate()
+
+        if p.returncode == 4:
+            # EINTR
+            time.sleep(dt)
+            dt *= 2
                 continue
+        elif p.returncode:
+            warnings.warn("libedit detection failed: %s"%err)
+            break
             else:
                 break
 
-    if status == 0 and len(result) > 0:
+    if p.returncode == 0 and re.search(r'/libedit[\.\d+]*\.dylib\s', otool):
         # we are bound to libedit - new in Leopard
         _rl.parse_and_bind("bind ^I rl_complete")
         warnings.warn("Leopard libedit detected - readline will not be well behaved "
             "including some crashes on tab completion, and incorrect history navigation. "
             "It is highly recommended that you install readline, "
             "which is easy_installable with: 'easy_install readline'",
             RuntimeWarning)
         uses_libedit = True
 
 
 # the clear_history() function was only introduced in Python 2.4 and is
 # actually optional in the readline API, so we must explicitly check for its
 # existence.  Some known platforms actually don't have it.  This thread:
 # http://mail.python.org/pipermail/python-dev/2003-August/037845.html
 # has the original discussion.
 
 if have_readline:
     try:
         _rl.clear_history
     except AttributeError:
         def clear_history(): pass
         _rl.clear_history = clear_history