From af86e5c72b3157112648d878a03a5fde2f508319 Mon Sep 17 00:00:00 2001
From: "Erik M. Bray" <erik.bray@lri.fr>
Date: Thu, 30 Nov 2017 14:15:08 +0000
Subject: [PATCH] Various fixes intended to ensure that opened files are closed
 explictly where necessary in order to avoid ResourceWarnings.

---
 src/sage/doctest/control.py | 17 +++++++++++++----
 src/sage/doctest/forker.py  | 24 ++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/src/sage/doctest/control.py b/src/sage/doctest/control.py
index 871092d3021..4236fd05e09 100644
--- a/src/sage/doctest/control.py
+++ b/src/sage/doctest/control.py
@@ -366,20 +366,29 @@ def __init__(self, options, args):
         # write to the actual standard output, regardless of
         # redirections.
         if options.serial:
-            real_stdout = os.fdopen(os.dup(sys.stdout.fileno()), "a")
+            self._real_stdout = os.fdopen(os.dup(sys.stdout.fileno()), "w")
+            self._close_stdout = True
         else:
             # Parallel mode: no special tricks needed
-            real_stdout = sys.stdout
+            self._real_stdout = sys.stdout
+            self._close_stdout = False
 
         if self.logfile is None:
-            self.logger = real_stdout
+            self.logger = self._real_stdout
         else:
-            self.logger = Logger(real_stdout, self.logfile)
+            self.logger = Logger(self._real_stdout, self.logfile)
 
         self.stats = {}
         self.load_stats(options.stats_path)
         self._init_warn_long()
 
+    def __del__(self):
+        if getattr(self, 'logfile', None) is not None:
+            self.logfile.close()
+
+        if getattr(self, '_close_stdout', False):
+            self._real_stdout.close()
+
     def _init_warn_long(self):
         """
         Pick a suitable default for the ``--warn-long`` option if not specified.
diff --git a/src/sage/doctest/forker.py b/src/sage/doctest/forker.py
index bcfce48d1d2..11a5386b8de 100644
--- a/src/sage/doctest/forker.py
+++ b/src/sage/doctest/forker.py
@@ -249,16 +249,20 @@ def __init__(self, outfile=None, infile=None):
         """
         if infile is None:
             self.infile = open(os.devnull)
+            self._close_infile = True
         else:
             self.infile = infile
+            self._close_infile = False
         if outfile is None:
             self.outfile = tempfile.TemporaryFile()
+            self._close_outfile = True
         else:
             self.outfile = outfile
+            self._close_outfile = False
         self.spoofing = False
         self.real_stdin = os.fdopen(os.dup(sys.stdin.fileno()), "r")
-        self.real_stdout = os.fdopen(os.dup(sys.stdout.fileno()), "a")
-        self.real_stderr = os.fdopen(os.dup(sys.stderr.fileno()), "a")
+        self.real_stdout = os.fdopen(os.dup(sys.stdout.fileno()), "w")
+        self.real_stderr = os.fdopen(os.dup(sys.stderr.fileno()), "w")
         self.position = 0
 
     def __del__(self):
@@ -276,6 +280,12 @@ def __del__(self):
             Not spoofed!
         """
         self.stop_spoofing()
+        if self._close_infile:
+            self.infile.close()
+        if self._close_outfile:
+            self.outfile.close()
+        for stream in ('stdin', 'stdout', 'stderr'):
+            getattr(self, 'real_' + stream).close()
 
     def start_spoofing(self):
         r"""
@@ -1974,6 +1984,10 @@ def run(self):
             task(self.options, self.outtmpfile, msgpipe, self.result_queue)
         finally:
             msgpipe.close()
+            # Note: This closes the tempfile in the child process, but in the
+            # parent process self.outtmpfile will not be closed yet, and can
+            # still be accessed in save_result_output
+            self.outtmpfile.close()
 
     def start(self):
         """
@@ -2072,6 +2086,11 @@ def save_result_output(self):
             ['cputime', 'err', 'failures', 'optionals', 'walltime']
             sage: len(W.output) > 0
             True
+
+        .. NOTE::
+
+            This method is called from the parent process, not from the
+            subprocess.
         """
         from six.moves.queue import Empty
         try:
@@ -2135,6 +2154,7 @@ def kill(self):
             sage: W.is_alive()
             False
         """
+
         if self.rmessages is not None:
             os.close(self.rmessages)
             self.rmessages = None