def read(self, timeout=None):
        """return 0 when finished
           else return 1 every timeout seconds
           data will be in outdata and errdata"""
        currtime=time.time()
        while 1:
            tocheck=[]
            if not self._outeof:
                tocheck.append(self.outr)
            if not self._erreof:
                tocheck.append(self.errr)
            ready = select.select(tocheck,[],[],timeout)
            if len(ready[0]) == 0: #no data timeout
                return 1
            else:
                if self.outr in ready[0]:
                    outchunk = os.read(self.outr,self.BUFSIZ)
                    if outchunk == '':
                        self._outeof = 1
                    self.outdata += outchunk
                if self.errr in ready[0]:
                    errchunk = os.read(self.errr,self.BUFSIZ)
                    if errchunk == '':
                        self._erreof = 1
                    self.errdata += errchunk
                if self._outeof and self._erreof:
                    return 0
                elif timeout:
                    if (time.time()-currtime) > timeout:
                        return 1 #may be more data but time to go
return 0 when finished
           else return 1 every timeout seconds
           data will be in outdata and errdata
recipes/Python/576387_unix_subprocess_wrapper/recipe-576387.py