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import os
import sys
import string
MAXFD = 256 # Max number of file descriptors (os.getdtablesize()???)
_active = []
def _cleanup():
for inst in _active[:]:
inst.poll()
class Popen3:
def __init__(self, cmd, capturestderr=0, bufsize=-1):
if type(cmd) == type(''):
cmd = ['/bin/sh', '-c', cmd]
p2cread, p2cwrite = os.pipe()
c2pread, c2pwrite = os.pipe()
if capturestderr:
errout, errin = os.pipe()
self.pid = os.fork()
if self.pid == 0:
# Child
os.close(0)
os.close(1)
if os.dup(p2cread) <> 0:
sys.stderr.write('popen2: bad read dup\n')
if os.dup(c2pwrite) <> 1:
sys.stderr.write('popen2: bad write dup\n')
if capturestderr:
os.close(2)
if os.dup(errin) <> 2: pass
for i in range(3, MAXFD):
try:
os.close(i)
except: pass
try:
os.execvp(cmd[0], cmd)
finally:
os._exit(1)
# Shouldn't come here, I guess
os._exit(1)
os.close(p2cread)
self.tochild = os.fdopen(p2cwrite, 'w', bufsize)
os.close(c2pwrite)
self.fromchild = os.fdopen(c2pread, 'r', bufsize)
if capturestderr:
os.close(errin)
self.childerr = os.fdopen(errout, 'r', bufsize)
else:
self.childerr = None
self.sts = -1 # Child not completed yet
_active.append(self)
def poll(self):
if self.sts < 0:
try:
pid, sts = os.waitpid(self.pid, os.WNOHANG)
if pid == self.pid:
self.sts = sts
_active.remove(self)
except os.error:
pass
return self.sts
def wait(self):
pid, sts = os.waitpid(self.pid, 0)
if pid == self.pid:
self.sts = sts
_active.remove(self)
return self.sts
def popen2(cmd, bufsize=-1):
_cleanup()
inst = Popen3(cmd, 0, bufsize)
return inst.fromchild, inst.tochild
def popen3(cmd, bufsize=-1):
_cleanup()
inst = Popen3(cmd, 1, bufsize)
return inst.fromchild, inst.tochild, inst.childerr
def _test():
teststr = "abc\n"
print "testing popen2..."
r, w = popen2('cat')
w.write(teststr)
w.close()
assert r.read() == teststr
print "testing popen3..."
r, w, e = popen3(['cat'])
w.write(teststr)
w.close()
assert r.read() == teststr
assert e.read() == ""
for inst in _active[:]:
inst.wait()
assert not _active
print "All OK"
if __name__ == '__main__':
_test()
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