OK, more fixes

xonsh/diff_history.py

@@ -301,13 +301,13 @@ def _dh_create_parser(p=None):
     return p
 
 
-def _dh_main_action(ns, hist=None):
+def _dh_main_action(ns, hist=None, stdout=None, stderr=None):
     hd = HistoryDiffer(ns.a, ns.b, reopen=ns.reopen, verbose=ns.verbose)
-    print_color(hd.format())
+    print_color(hd.format(), file=stdout)
 
 
-def diff_history_main(args=None, stdin=None):
+def diff_history_main(args=None, stdin=None, stdout=None, stderr=None):
     """Main entry point for history diff'ing"""
     parser = _dh_create_parser()
     ns = parser.parse_args(args)
-    _dh_main_action(ns)
+    _dh_main_action(ns, stdout=stdout)

xonsh/history.py

@@ -443,7 +443,7 @@ def _hist_get(session='session', *, slices=None, datetime_format=None,
     return cmds
 
 
-def _hist_show(ns, *args, **kwargs):
+def _hist_show(ns, hist=None, stdout=None, stderr=None):
     """Show the requested portion of shell history.
     Accepts same parameters with `_hist_get`.
     """
@@ -454,24 +454,24 @@ def _hist_show(ns, *args, **kwargs):
                              end_time=ns.end_time,
                              datetime_format=ns.datetime_format)
     except ValueError as err:
-        print("history: error: {}".format(err), file=sys.stderr)
+        print("history: error: {}".format(err), file=stderr)
         return
     if ns.reverse:
         commands = reversed(list(commands))
     if not ns.numerate and not ns.timestamp:
         for c, _, _ in commands:
-            print(c)
+            print(c, file=stdout)
     elif not ns.timestamp:
         for c, _, i in commands:
-            print('{}: {}'.format(i, c))
+            print('{}: {}'.format(i, c), file=stdout)
     elif not ns.numerate:
         for c, ts, _ in commands:
             dt = datetime.datetime.fromtimestamp(ts).ctime()
-            print('({}) {}'.format(dt, c))
+            print('({}) {}'.format(dt, c), file=stdout)
     else:
         for c, ts, i in commands:
             dt = datetime.datetime.fromtimestamp(ts).ctime()
-            print('{}:({}) {}'.format(i, dt, c))
+            print('{}:({}) {}'.format(i, dt, c), file=stdout)
 
 
 # Interface to History
@@ -689,7 +689,7 @@ class History(object):
                               'you can create new though.')
 
 
-def _hist_info(ns, hist):
+def _hist_info(ns, hist, stdout, stderr):
     """Display information about the shell history."""
     data = collections.OrderedDict()
     data['sessionid'] = str(hist.sessionid)
@@ -699,10 +699,10 @@ def _hist_info(ns, hist):
     data['bufferlength'] = len(hist.buffer)
     if ns.json:
         s = json.dumps(data)
-        print(s)
+        print(s, file=stdout)
     else:
         lines = ['{0}: {1}'.format(k, v) for k, v in data.items()]
-        print('\n'.join(lines))
+        print('\n'.join(lines), file=stdout)
 
 
 def _hist_gc(ns, hist):
@@ -726,12 +726,12 @@ def _HIST_SESSIONS():
 def _HIST_MAIN_ACTIONS():
     return {
         'show': _hist_show,
-        'id': lambda ns, hist: print(hist.sessionid),
-        'file': lambda ns, hist: print(hist.filename),
+        'id': lambda ns, hist, stdout, stderr: print(hist.sessionid, file=stdout),
+        'file': lambda ns, hist, stdout, stderr: print(hist.filename, file=stdout),
         'info': _hist_info,
         'diff': _dh_main_action,
         'gc': _hist_gc,
-    }
+        }
 
 
 def _hist_parse_args(args):
@@ -759,9 +759,9 @@ def _hist_parse_args(args):
     return ns
 
 
-def history_main(args=None, stdin=None):
+def history_main(args=None, stdin=None, stdout=None, stderr=None):
     """This is the history command entry point."""
     hist = builtins.__xonsh_history__
     ns = _hist_parse_args(args)
     if ns:
-        _HIST_MAIN_ACTIONS[ns.action](ns, hist)
+        _HIST_MAIN_ACTIONS[ns.action](ns, hist, stdout, stderr)

xonsh/proc.py

@@ -491,6 +491,18 @@ def safe_flush(handle):
     return status
 
 
+def still_writable(fd):
+    """Determines whether a file descriptior is still writable by trying to
+    write an empty string and seeing if it fails.
+    """
+    try:
+        os.write(fd, b'')
+        status = True
+    except OSError:
+        status = False
+    return status
+
+
 class PopenThread(threading.Thread):
     """A thread for running and managing subprocess. This allows reading
     from the stdin, stdout, and stderr streams in a non-blocking fashion.
@@ -1010,8 +1022,11 @@ class FileThreadDispatcher:
         extra sure the string was written.
         """
         h = self.handle
-        r = h.write(s)
-        safe_flush(h)
+        try:
+            r = h.write(s)
+            h.flush()
+        except OSError:
+            r = None
         return r
 
     @property
@@ -1286,6 +1301,21 @@ class ProcProxyThread(threading.Thread):
                 r = self.f(self.args, sp_stdin, sp_stdout, sp_stderr, spec)
         except SystemExit as e:
             r = e.code if isinstance(e.code, int) else int(bool(e.code))
+        except OSError as e:
+            status = still_writable(self.c2pwrite) and \
+                     still_writable(self.errwrite)
+            if status:
+                # stdout and stderr are still writable, so error must
+                # come from function itself.
+                print_exception()
+                r = 1
+            else:
+                # stdout and stderr are no longer writable, so error must
+                # come from the fact that the next process in the pipeline
+                # has closed the other side of the pipe. The function then
+                # attempted to write to this side of the pipe anyway. This
+                # is not truly an error and we should exit gracefully.
+                r = 0
         except Exception:
             print_exception()
             r = 1