SpawnProcess: work around array.fromfile() bugs

When I extended test_poll to test SpawnProcess array.fromfile() usage,
it exposed bugs in array.fromfile() that I couldn't find a way to
handle. So, use os.read() instead.

2 files changed, 39 insertions, 15 deletions

diff --git a/pym/_emerge/AbstractPollTask.py b/pym/_emerge/AbstractPollTask.py
index f7f3a9526..ea13587bc 100644
--- a/pym/_emerge/AbstractPollTask.py
+++ b/pym/_emerge/AbstractPollTask.py
@@ -2,7 +2,9 @@
 # Distributed under the terms of the GNU General Public License v2
 
 import array
+import errno
 import logging
+import os
 
 from portage.util import writemsg_level
 from _emerge.AsynchronousTask import AsynchronousTask
@@ -20,7 +22,7 @@ class AbstractPollTask(AsynchronousTask):
 	def isAlive(self):
 		return bool(self._registered)
 
-	def _read_buf(self, f, event):
+	def _read_buf(self, fd, event):
 		"""
 		| POLLIN | RETURN
 		| BIT    | VALUE
@@ -32,13 +34,26 @@ class AbstractPollTask(AsynchronousTask):
 		| ---------------------------------------------------
 		| 0      | None
 		"""
+		# NOTE: array.fromfile() is no longer used here because it has
+		# bugs in all known versions of Python (including Python 2.7
+		# and Python 3.2).
 		buf = None
 		if event & PollConstants.POLLIN:
 			buf = array.array('B')
 			try:
-				buf.fromfile(f, self._bufsize)
-			except (EOFError, IOError):
-				pass
+				# Python >=3.2
+				frombytes = buf.frombytes
+			except AttributeError:
+				frombytes = buf.fromstring
+			try:
+				frombytes(os.read(fd, self._bufsize))
+			except OSError as e:
+				# EIO happens with pty on Linux after the
+				# slave end of the pty has been closed.
+				if e.errno not in (errno.EAGAIN, errno.EIO):
+					raise
+				buf = None
+
 		return buf
 
 	def _unregister(self):
diff --git a/pym/_emerge/SpawnProcess.py b/pym/_emerge/SpawnProcess.py
index 84493fe42..c2f492873 100644
--- a/pym/_emerge/SpawnProcess.py
+++ b/pym/_emerge/SpawnProcess.py
@@ -165,11 +165,20 @@ class SpawnProcess(SubProcess):
 	def _output_handler(self, fd, event):
 
 		files = self._files
-		buf = self._read_buf(files.process, event)
+		while True:
+			buf = self._read_buf(fd, event)
 
-		if buf is not None:
+			if buf is None:
+				# not a POLLIN event, EAGAIN, etc...
+				break
 
-			if buf:
+			if not buf:
+				# EOF
+				self._unregister()
+				self.wait()
+				break
+
+			else:
 				if not self.background:
 					write_successful = False
 					failures = 0
@@ -217,9 +226,6 @@ class SpawnProcess(SubProcess):
 						data = buf.tostring()
 					files.log.write(data)
 				files.log.flush()
-			else:
-				self._unregister()
-				self.wait()
 
 		self._unregister_if_appropriate(event)
 
@@ -230,15 +236,18 @@ class SpawnProcess(SubProcess):
 		monitor the process from inside a poll() loop.
 		"""
 
-		buf = self._read_buf(self._files.process, event)
+		while True:
+			buf = self._read_buf(fd, event)
 
-		if buf is not None:
+			if buf is None:
+				# not a POLLIN event, EAGAIN, etc...
+				break
 
-			if buf:
-				pass
-			else:
+			if not buf:
+				# EOF
 				self._unregister()
 				self.wait()
+				break
 
 		self._unregister_if_appropriate(event)