Issue #10963: Ensure that subprocess.communicate() never raises EPIPE.

Lib/subprocess.py

@@ -326,6 +326,7 @@ class Popen(args, bufsize=0, executable=None,
 import traceback
 import gc
 import signal
+import errno
 
 # Exception classes used by this module.
 class CalledProcessError(Exception):
@@ -358,7 +359,6 @@ class pywintypes:
 else:
     import select
     _has_poll = hasattr(select, 'poll')
-    import errno
     import fcntl
     import pickle
 
@@ -699,7 +699,11 @@ def communicate(self, input=None):
             stderr = None
             if self.stdin:
                 if input:
-                    self.stdin.write(input)
+                    try:
+                        self.stdin.write(input)
+                    except IOError as e:
+                        if e.errno != errno.EPIPE and e.errno != errno.EINVAL:
+                            raise
                 self.stdin.close()
             elif self.stdout:
                 stdout = self.stdout.read()
@@ -929,7 +933,11 @@ def _communicate(self, input):
 
             if self.stdin:
                 if input is not None:
-                    self.stdin.write(input)
+                    try:
+                        self.stdin.write(input)
+                    except IOError as e:
+                        if e.errno != errno.EPIPE:
+                            raise
                 self.stdin.close()
 
             if self.stdout:
@@ -1290,9 +1298,16 @@ def close_unregister_and_remove(fd):
                 for fd, mode in ready:
                     if mode & select.POLLOUT:
                         chunk = input[input_offset : input_offset + _PIPE_BUF]
-                        input_offset += os.write(fd, chunk)
-                        if input_offset >= len(input):
-                            close_unregister_and_remove(fd)
+                        try:
+                            input_offset += os.write(fd, chunk)
+                        except OSError as e:
+                            if e.errno == errno.EPIPE:
+                                close_unregister_and_remove(fd)
+                            else:
+                                raise
+                        else:
+                            if input_offset >= len(input):
+                                close_unregister_and_remove(fd)
                     elif mode & select_POLLIN_POLLPRI:
                         data = os.read(fd, 4096)
                         if not data:
@@ -1334,11 +1349,19 @@ def _communicate_with_select(self, input):
 
                 if self.stdin in wlist:
                     chunk = input[input_offset : input_offset + _PIPE_BUF]
-                    bytes_written = os.write(self.stdin.fileno(), chunk)
-                    input_offset += bytes_written
-                    if input_offset >= len(input):
-                        self.stdin.close()
-                        write_set.remove(self.stdin)
+                    try:
+                        bytes_written = os.write(self.stdin.fileno(), chunk)
+                    except OSError as e:
+                        if e.errno == errno.EPIPE:
+                            self.stdin.close()
+                            write_set.remove(self.stdin)
+                        else:
+                            raise
+                    else:
+                        input_offset += bytes_written
+                        if input_offset >= len(input):
+                            self.stdin.close()
+                            write_set.remove(self.stdin)
 
                 if self.stdout in rlist:
                     data = os.read(self.stdout.fileno(), 1024)

Lib/test/test_subprocess.py

@@ -592,6 +592,25 @@ def test_handles_closed_on_exception(self):
         self.assertFalse(os.path.exists(ofname))
         self.assertFalse(os.path.exists(efname))
 
+    def test_communicate_epipe(self):
+        # Issue 10963: communicate() should hide EPIPE
+        p = subprocess.Popen([sys.executable, "-c", 'pass'],
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        self.addCleanup(p.stdout.close)
+        self.addCleanup(p.stderr.close)
+        self.addCleanup(p.stdin.close)
+        p.communicate(b"x" * 2**20)
+
+    def test_communicate_epipe_only_stdin(self):
+        # Issue 10963: communicate() should hide EPIPE
+        p = subprocess.Popen([sys.executable, "-c", 'pass'],
+                             stdin=subprocess.PIPE)
+        self.addCleanup(p.stdin.close)
+        time.sleep(2)
+        p.communicate(b"x" * 2**20)
+
     #
     # POSIX tests
     #

Misc/NEWS

@@ -44,6 +44,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #10963: Ensure that subprocess.communicate() never raises EPIPE.
+
 - Issue #11696: Fix ID generation in msilib.
 
 - Issue #9696: Fix exception incorrectly raised by xdrlib.Packer.pack_int when