subprocess.py 文件源码

def _communicate_with_poll(self, input):
            stdout = None # Return
            stderr = None # Return
            fd2file = {}
            fd2output = {}

            poller = select.poll()
            def register_and_append(file_obj, eventmask):
                poller.register(file_obj.fileno(), eventmask)
                fd2file[file_obj.fileno()] = file_obj

            def close_unregister_and_remove(fd):
                poller.unregister(fd)
                fd2file[fd].close()
                fd2file.pop(fd)

            if self.stdin and input:
                register_and_append(self.stdin, select.POLLOUT)

            select_POLLIN_POLLPRI = select.POLLIN | select.POLLPRI
            if self.stdout:
                register_and_append(self.stdout, select_POLLIN_POLLPRI)
                fd2output[self.stdout.fileno()] = stdout = []
            if self.stderr:
                register_and_append(self.stderr, select_POLLIN_POLLPRI)
                fd2output[self.stderr.fileno()] = stderr = []

            input_offset = 0
            while fd2file:
                try:
                    ready = poller.poll()
                except select.error, e:
                    if e.args[0] == errno.EINTR:
                        continue
                    raise

                for fd, mode in ready:
                    if mode & select.POLLOUT:
                        chunk = input[input_offset : input_offset + _PIPE_BUF]
                        try:
                            input_offset += os.write(fd, chunk)
                        except OSError as e:
                            if e.errno == errno.EPIPE:
                                close_unregister_and_remove(fd)
                            else:
                                raise
                        else:
                            if input_offset >= len(input):
                                close_unregister_and_remove(fd)
                    elif mode & select_POLLIN_POLLPRI:
                        data = os.read(fd, 4096)
                        if not data:
                            close_unregister_and_remove(fd)
                        fd2output[fd].append(data)
                    else:
                        # Ignore hang up or errors.
                        close_unregister_and_remove(fd)

            return (stdout, stderr)