1 files changed, 25 insertions, 15 deletions

diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 60b0a9e545..c92b324afd 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -269,7 +269,7 @@ def synopsis(filename, cache={}):
             except:
                 return None
             del sys.modules['__temp__']
-            result = (module.__doc__ or '').splitlines()[0]
+            result = module.__doc__.splitlines()[0] if module.__doc__ else None
         # Cache the result.
         cache[filename] = (mtime, result)
     return result
@@ -1405,9 +1405,6 @@ class _PlainTextDoc(TextDoc):
 def pager(text):
     """The first time this is called, determine what kind of pager to use."""
     global pager
-    # Escape non-encodable characters to avoid encoding errors later
-    encoding = sys.getfilesystemencoding()
-    text = text.encode(encoding, 'backslashreplace').decode(encoding)
     pager = getpager()
     pager(text)
 
@@ -1450,10 +1447,12 @@ def plain(text):
 
 def pipepager(text, cmd):
     """Page through text by feeding it to another program."""
-    pipe = os.popen(cmd, 'w')
+    import subprocess
+    proc = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE)
     try:
-        pipe.write(text)
-        pipe.close()
+        with proc:
+            with io.TextIOWrapper(proc.stdin, errors='backslashreplace') as pipe:
+                pipe.write(text)
     except OSError:
         pass # Ignore broken pipes caused by quitting the pager program.
 
@@ -1461,16 +1460,21 @@ def tempfilepager(text, cmd):
     """Page through text by invoking a program on a temporary file."""
     import tempfile
     filename = tempfile.mktemp()
-    with open(filename, 'w') as file:
+    with open(filename, 'w', errors='backslashreplace') as file:
         file.write(text)
     try:
         os.system(cmd + ' "' + filename + '"')
     finally:
         os.unlink(filename)
 
+def _escape_stdout(text):
+    # Escape non-encodable characters to avoid encoding errors later
+    encoding = getattr(sys.stdout, 'encoding', None) or 'utf-8'
+    return text.encode(encoding, 'backslashreplace').decode(encoding)
+
 def ttypager(text):
     """Page through text on a text terminal."""
-    lines = plain(text).split('\n')
+    lines = plain(_escape_stdout(text)).split('\n')
     try:
         import tty
         fd = sys.stdin.fileno()
@@ -1514,7 +1518,7 @@ def ttypager(text):
 
 def plainpager(text):
     """Simply print unformatted text.  This is the ultimate fallback."""
-    sys.stdout.write(plain(text))
+    sys.stdout.write(plain(_escape_stdout(text)))
 
 def describe(thing):
     """Produce a short description of the given thing."""
@@ -1573,7 +1577,10 @@ def resolve(thing, forceload=0):
     if isinstance(thing, str):
         object = locate(thing, forceload)
         if not object:
-            raise ImportError('no Python documentation found for %r' % thing)
+            raise ImportError('''\
+No Python documentation found for %r.
+Use help() to get the interactive help utility.
+Use help(str) for help on the str class.''' % thing)
         return object, thing
     else:
         name = getattr(thing, '__name__', None)
@@ -1844,7 +1851,10 @@ has the same effect as typing a particular string at the help> prompt.
                 break
             request = replace(request, '"', '', "'", '').strip()
             if request.lower() in ('q', 'quit'): break
-            self.help(request)
+            if request == 'help':
+                self.intro()
+            else:
+                self.help(request)
 
     def getline(self, prompt):
         """Read one line, using input() when appropriate."""
@@ -1858,8 +1868,7 @@ has the same effect as typing a particular string at the help> prompt.
     def help(self, request):
         if type(request) is type(''):
             request = request.strip()
-            if request == 'help': self.intro()
-            elif request == 'keywords': self.listkeywords()
+            if request == 'keywords': self.listkeywords()
             elif request == 'symbols': self.listsymbols()
             elif request == 'topics': self.listtopics()
             elif request == 'modules': self.listmodules()
@@ -1872,6 +1881,7 @@ has the same effect as typing a particular string at the help> prompt.
             elif request in self.keywords: self.showtopic(request)
             elif request in self.topics: self.showtopic(request)
             elif request: doc(request, 'Help on %s:', output=self._output)
+            else: doc(str, 'Help on %s:', output=self._output)
         elif isinstance(request, Helper): self()
         else: doc(request, 'Help on %s:', output=self._output)
         self.output.write('\n')
@@ -2073,7 +2083,7 @@ class ModuleScanner:
                         if onerror:
                             onerror(modname)
                         continue
-                    desc = (module.__doc__ or '').splitlines()[0]
+                    desc = module.__doc__.splitlines()[0] if module.__doc__ else ''
                     path = getattr(module,'__file__',None)
                 name = modname + ' - ' + desc
                 if name.lower().find(key) >= 0: