Python 与沙盒PyPy解释器交互-secondary.communicate（）返回空元组

我正在尝试创建一种从普通（非沙盒）cPython或pypypy脚本中与沙盒pypypy解释器交互的方法

我已经能够按照这些指令编译一个沙盒pypypy解释器，并且我有一个PyPy-c-sandbox文件，该文件与PyPy_interact.py一起工作，以创建一个交互式沙盒解释器

现在我想做一件非常类似的事情，但我不想使用stdin/stdout作为io，而是想使用python脚本与pypy沙盒进程交互。我大部分时间都在工作。我可以将.communicate（）函数与cStringIO对象一起用作输入、输出和错误，并从普通python访问这些数据

然而，这是我的问题，当我在同一个实例化的PyPy沙盒对象上第二次调用.communicate（）时，我没有得到任何回报。这只是第一次。沟通是有效的。我很困惑为什么会这样，以及如何避开它

我拼凑了一个丑陋的黑客来证明我的问题：

import sys, os
import autopath
from pypy.translator.sandbox.sandlib import SimpleIOSandboxedProc
from pypy.translator.sandbox.sandlib import VirtualizedSandboxedProc
from pypy.translator.sandbox.vfs import Dir, RealDir, RealFile
import pypy


LIB_ROOT = os.path.dirname(os.path.dirname(pypy.__file__))

class PyPySandboxedProc(VirtualizedSandboxedProc, SimpleIOSandboxedProc):
    argv0 = '/bin/pypy-c'
    virtual_cwd = '/tmp'
    virtual_env = {}
    virtual_console_isatty = True
    arguments = ['../goal/pypy-c', '-u']

    def __init__(self, executable, arguments, tmpdir=None, debug=True):
        self.executable = executable = os.path.abspath(executable)
        self.tmpdir = tmpdir
        self.debug = debug
        super(PyPySandboxedProc, self).__init__([self.argv0] + arguments,
                                                executable=executable)

    def build_virtual_root(self):
        # build a virtual file system:
        # * can access its own executable
        # * can access the pure Python libraries
        # * can access the temporary usession directory as /tmp
        exclude = ['.pyc', '.pyo']
        if self.tmpdir is None:
            tmpdirnode = Dir({})
        else:
            tmpdirnode = RealDir(self.tmpdir, exclude=exclude)
        libroot = str(LIB_ROOT)

        return Dir({
            'bin': Dir({
                'pypy-c': RealFile(self.executable),
                'lib-python': RealDir(os.path.join(libroot, 'lib-python'),
                                      exclude=exclude),
                'lib_pypy': RealDir(os.path.join(libroot, 'lib_pypy'),
                                      exclude=exclude),
                }),
             'tmp': tmpdirnode,
             })

# run test
arguments = ['../goal/pypy-c', '-u']

sandproc = PyPySandboxedProc(arguments[0], arguments[1:],
                             tmpdir=None, debug=True)

#start the proc
code1 = "print 'started'\na = 5\nprint a"
code2 = "b = a\nprint b\nprint 'code 2 was run'"

output, error = sandproc.communicate(code1)
print "output: %s\n error: %s\n" % (output, error)

output, error = sandproc.communicate(code2)
print "output: %s\n error: %s\n" % (output, error)

我真的很想通过某种方式让

code2

由同一个sandproc实例运行，但要单独返回它的输入/输出。如果我将所有代码连接在一起并同时运行它，它会工作，但是解析给定输入的输出会有点麻烦

from rpython.translator.sandbox.sandlib import SimpleIOSandboxedProc

您正在PySandboxedProc中导入和扩展SimpleOsandBoxedProc。在source（）中，您将看到sandproc.communicate（）在子进程终止后发送数据并返回

def communicate(self, input=None):
    """Send data to stdin. Read data from stdout and stderr,
    until end-of-file is reached. Wait for process to terminate.
    """
    import cStringIO
    if input:
        if isinstance(input, str):
            input = cStringIO.StringIO(input)
        self._input = input
    self._output = cStringIO.StringIO()
    self._error = cStringIO.StringIO()
    self.handle_forever()
    output = self._output.getvalue()
    self._output = None
    error = self._error.getvalue()
    self._error = None
    return (output, error)

在上面的代码中，self.handle_forever（）被调用：

def handle_until_return(self):
    child_stdin  = self.popen.stdin
    child_stdout = self.popen.stdout
    if self.os_level_sandboxing and sys.platform.startswith('linux'):
        # rationale: we wait until the child process started completely,
        # letting the C library do any system calls it wants for
        # initialization.  When the RPython code starts up, it quickly
        # does its first system call.  At this point we turn seccomp on.
        import select
        select.select([child_stdout], [], [])
        f = open('/proc/%d/seccomp' % self.popen.pid, 'w')
        print >> f, 1
        f.close()
    while True:
        try:
            fnname = read_message(child_stdout)
            args   = read_message(child_stdout)
        except EOFError, e:
            break
        if self.log and not self.is_spam(fnname, *args):
            self.log.call('%s(%s)' % (fnname,
                                 ', '.join([shortrepr(x) for x in args])))
        try:
            answer, resulttype = self.handle_message(fnname, *args)
        except Exception, e:
            tb = sys.exc_info()[2]
            write_exception(child_stdin, e, tb)
            if self.log:
                if str(e):
                    self.log.exception('%s: %s' % (e.__class__.__name__, e))
                else:
                    self.log.exception('%s' % (e.__class__.__name__,))
        else:
            if self.log and not self.is_spam(fnname, *args):
                self.log.result(shortrepr(answer))
            try:
                write_message(child_stdin, 0)  # error code - 0 for ok
                write_message(child_stdin, answer, resulttype)
                child_stdin.flush()
            except (IOError, OSError):
                # likely cause: subprocess is dead, child_stdin closed
                if self.poll() is not None:
                    break
                else:
                    raise
    returncode = self.wait()
    return returncode

可以看出，是一个“while True:”，这意味着该函数将不会返回，直到我们得到一个抛出的异常因此，sandproc.communicate（）无法实现您希望它实现的目标

你有两个选择

硬选项是分叉您的主要流程。使用一个进程运行sandproc.interact（），并传递一些os.pipes。并使用另一个进程对所述管道进行读写。这是低效的，因为它需要3个进程（一个用于沙盒应用程序，一个用于主进程，一个用于分叉进程）

简单选项用于覆盖SimpleOsandBoxedProc类中的某些函数。您所要做的就是在pysandboxedproc中重新实现这些函数

def do_ll_os__ll_os_read(self, fd, size):
    if fd == 0:
        if self._input is None:
            return ""
        elif (getattr(self, 'virtual_console_isatty', False) or
              self._input.isatty()):
            # don't wait for all 'size' chars if reading from a tty,
            # to avoid blocking.  Instead, stop after reading a line.

            # For now, waiting at the interactive console is the
            # only time that counts as idle.
            self.enter_idle()
            try:
                inputdata = self._input.readline(size) #TODO: THIS IS WHERE YOU HANDLE READING FROM THE SANDBOXED PROCESS
            finally:
                self.leave_idle()
        else:
            inputdata = self._input.read(size)
        if self.inputlogfile is not None:
            self.inputlogfile.write(inputdata)
        return inputdata
    raise OSError("trying to read from fd %d" % (fd,))

def do_ll_os__ll_os_write(self, fd, data):
    if fd == 1:
        self._output.write(data) #TODO: THIS IS WHERE YOU WRITE TO THE SANDBOXED PROCESS
        return len(data)
    if fd == 2:
        self._error.write(data)
        return len(data)
    raise OSError("trying to write to fd %d" % (fd,))

用#TODO:标签注释的行是从沙盒进程注入和读取数据的地方

---

您需要做的是实现这样的逻辑：写入一些数据（当沙盒进程读取时）、等待响应（直到进程写入）、写入更多数据，然后再次读取响应（当进程第二次写入时）。

通信结束，进程退出。看看在sandlib中如何处理_，直到_return被实现，从而了解如何逐段执行。