SpawnProcess: split out a PipeLogger class

The copyright dates for these classes begin in 2008, since SpawnProcess
code is derived from the EbuildFetcherAsync class which was added in
commit e4edadf5ae7063f375d76be151c6d0e949980ecf in 2008.

1 files changed, 149 insertions, 0 deletions

diff --git a/pym/portage/util/_async/PipeLogger.py b/pym/portage/util/_async/PipeLogger.py
new file mode 100644
index 000000000..dbdd56f2a
--- /dev/null
+++ b/pym/portage/util/_async/PipeLogger.py
@@ -0,0 +1,149 @@
+# Copyright 2008-2012 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+import fcntl
+import errno
+import gzip
+
+import portage
+from portage import os, _encodings, _unicode_encode
+from _emerge.AbstractPollTask import AbstractPollTask
+
+class PipeLogger(AbstractPollTask):
+
+	"""
+	This can be used for logging output of a child process,
+	optionally outputing to log_file_path and/or stdout_fd.  It can
+	also monitor for EOF on input_fd, which may be used to detect
+	termination of a child process. If log_file_path ends with
+	'.gz' then the log file is written with compression.
+	"""
+
+	__slots__ = ("input_fd", "log_file_path", "stdout_fd") + \
+		("_log_file", "_log_file_real", "_reg_id")
+
+	def _start(self):
+
+		log_file_path = self.log_file_path
+		if log_file_path is not None:
+
+			self._log_file = open(_unicode_encode(log_file_path,
+				encoding=_encodings['fs'], errors='strict'), mode='ab')
+			if log_file_path.endswith('.gz'):
+				self._log_file_real = self._log_file
+				self._log_file = gzip.GzipFile(filename='', mode='ab',
+					fileobj=self._log_file)
+
+			portage.util.apply_secpass_permissions(log_file_path,
+				uid=portage.portage_uid, gid=portage.portage_gid,
+				mode=0o660)
+
+		fcntl.fcntl(self.input_fd, fcntl.F_SETFL,
+			fcntl.fcntl(self.input_fd, fcntl.F_GETFL) | os.O_NONBLOCK)
+
+		self._reg_id = self.scheduler.io_add_watch(self.input_fd,
+			self._registered_events, self._output_handler)
+		self._registered = True
+
+	def isAlive(self):
+		return self._registered
+
+	def _cancel(self):
+		self._unregister()
+		if self.returncode is None:
+			self.returncode = self._cancelled_returncode
+
+	def _wait(self):
+		if self.returncode is not None:
+			return self.returncode
+		self._wait_loop()
+		self.returncode = os.EX_OK
+		return self.returncode
+
+	def _output_handler(self, fd, event):
+
+		background = self.background
+		stdout_fd = self.stdout_fd
+		log_file = self._log_file 
+
+		while True:
+			buf = self._read_buf(fd, event)
+
+			if buf is None:
+				# not a POLLIN event, EAGAIN, etc...
+				break
+
+			if not buf:
+				# EOF
+				self._unregister()
+				self.wait()
+				break
+
+			else:
+				if not background and stdout_fd is not None:
+					write_successful = False
+					failures = 0
+					while True:
+						try:
+							if not write_successful:
+								os.write(stdout_fd, buf)
+								write_successful = True
+							break
+						except OSError as e:
+							if e.errno != errno.EAGAIN:
+								raise
+							del e
+							failures += 1
+							if failures > 50:
+								# Avoid a potentially infinite loop. In
+								# most cases, the failure count is zero
+								# and it's unlikely to exceed 1.
+								raise
+
+							# This means that a subprocess has put an inherited
+							# stdio file descriptor (typically stdin) into
+							# O_NONBLOCK mode. This is not acceptable (see bug
+							# #264435), so revert it. We need to use a loop
+							# here since there's a race condition due to
+							# parallel processes being able to change the
+							# flags on the inherited file descriptor.
+							# TODO: When possible, avoid having child processes
+							# inherit stdio file descriptors from portage
+							# (maybe it can't be avoided with
+							# PROPERTIES=interactive).
+							fcntl.fcntl(stdout_fd, fcntl.F_SETFL,
+								fcntl.fcntl(stdout_fd,
+								fcntl.F_GETFL) ^ os.O_NONBLOCK)
+
+				if log_file is not None:
+					log_file.write(buf)
+					log_file.flush()
+
+		self._unregister_if_appropriate(event)
+
+		return True
+
+	def _unregister(self):
+
+		if self._reg_id is not None:
+			self.scheduler.source_remove(self._reg_id)
+			self._reg_id = None
+
+		if self.input_fd is not None:
+			os.close(self.input_fd)
+			self.input_fd = None
+
+		if self.stdout_fd is not None:
+			os.close(self.stdout_fd)
+			self.stdout_fd = None
+
+		if self._log_file is not None:
+			self._log_file.close()
+			self._log_file = None
+
+		if self._log_file_real is not None:
+			# Avoid "ResourceWarning: unclosed file" since python 3.2.
+			self._log_file_real.close()
+			self._log_file_real = None
+
+		self._registered = False