test_ok2/py/io/fdcapture.py

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import os
import sys
import py
import tempfile
class FDCapture:
""" Capture IO to/from a given os-level filedescriptor. """
def __init__(self, targetfd, tmpfile=None):
self.targetfd = targetfd
if tmpfile is None:
tmpfile = self.maketmpfile()
self.tmpfile = tmpfile
self._savefd = os.dup(targetfd)
os.dup2(self.tmpfile.fileno(), targetfd)
self._patched = []
def setasfile(self, name, module=sys):
""" patch <module>.<name> to self.tmpfile
"""
key = (module, name)
self._patched.append((key, getattr(module, name)))
setattr(module, name, self.tmpfile)
def unsetfiles(self):
""" unpatch all patched items
"""
while self._patched:
(module, name), value = self._patched.pop()
setattr(module, name, value)
def done(self):
""" unpatch and clean up, returns the self.tmpfile (file object)
"""
os.dup2(self._savefd, self.targetfd)
self.unsetfiles()
os.close(self._savefd)
self.tmpfile.seek(0)
return self.tmpfile
def maketmpfile(self):
""" create a temporary file
"""
f = tempfile.TemporaryFile()
newf = py.io.dupfile(f)
f.close()
return newf
def writeorg(self, str):
""" write a string to the original file descriptor
"""
tempfp = tempfile.TemporaryFile()
try:
os.dup2(self._savefd, tempfp.fileno())
tempfp.write(str)
finally:
tempfp.close()