Question

我害怕把它发送到distutils邮件列表，因为我很确定我是在愚蠢的误解。

以下是_spawn_posix版本2.7.9中的函数distutils：

def _spawn_posix(cmd, search_path=1, verbose=0, dry_run=0):
    log.info(' '.join(cmd))
    if dry_run:
        return
    executable = cmd[0]
    exec_fn = search_path and os.execvp or os.execv
    env = None
    if sys.platform == 'darwin':
        global _cfg_target, _cfg_target_split
        if _cfg_target is None:
            _cfg_target = sysconfig.get_config_var(
                                  'MACOSX_DEPLOYMENT_TARGET') or ''
            if _cfg_target:
                _cfg_target_split = [int(x) for x in _cfg_target.split('.')]
        if _cfg_target:
            # ensure that the deployment target of build process is not less
            # than that used when the interpreter was built. This ensures
            # extension modules are built with correct compatibility values
            cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target)
            if _cfg_target_split > [int(x) for x in cur_target.split('.')]:
                my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: '
                          'now "%s" but "%s" during configure'
                                % (cur_target, _cfg_target))
                raise DistutilsPlatformError(my_msg)
            env = dict(os.environ,
                       MACOSX_DEPLOYMENT_TARGET=cur_target)
            exec_fn = search_path and os.execvpe or os.execve
    pid = os.fork()

    if pid == 0:  # in the child
        try:
            if env is None:
                exec_fn(executable, cmd)
            else:
                exec_fn(executable, cmd, env)
        except OSError, e:
            if not DEBUG:
                cmd = executable
            sys.stderr.write("unable to execute %r: %s\n" %
                             (cmd, e.strerror))
            os._exit(1)

        if not DEBUG:
            cmd = executable
        sys.stderr.write("unable to execute %r for unknown reasons" % cmd)
        os._exit(1)
    else:   # in the parent
        # Loop until the child either exits or is terminated by a signal
        # (ie. keep waiting if it's merely stopped)
        while 1:
            try:
                pid, status = os.waitpid(pid, 0)
            except OSError, exc:
                import errno
                if exc.errno == errno.EINTR:
                    continue
                if not DEBUG:
                    cmd = executable
                raise DistutilsExecError, \
                      "command %r failed: %s" % (cmd, exc[-1])
            if os.WIFSIGNALED(status):
                if not DEBUG:
                    cmd = executable
                raise DistutilsExecError, \
                      "command %r terminated by signal %d" % \
                      (cmd, os.WTERMSIG(status))

            elif os.WIFEXITED(status):
                exit_status = os.WEXITSTATUS(status)
                if exit_status == 0:
                    return   # hey, it succeeded!
                else:
                    if not DEBUG:
                        cmd = executable
                    raise DistutilsExecError, \
                          "command %r failed with exit status %d" % \
                          (cmd, exit_status)

            elif os.WIFSTOPPED(status):
                continue

            else:
                if not DEBUG:
                    cmd = executable
                raise DistutilsExecError, \
                      "unknown error executing %r: termination status %d" % \
                      (cmd, status)

显然那里有很多。没有人想读这个。您需要做的就是：

找到第exec_fn(executable, cmd)行。这就是整个功能设置执行的界限。它会调用os.execvp。
请注意exec_fn仅在pid == 0。

请注意，pid == 0时会调用以下代码：

    try:
        if env is None:
            exec_fn(executable, cmd)
        else:
            exec_fn(executable, cmd, env)
    except OSError, e:
        if not DEBUG:
            cmd = executable
        sys.stderr.write("unable to execute %r: %s\n" %
                         (cmd, e.strerror))
        os._exit(1)

    if not DEBUG:
        cmd = executable
    sys.stderr.write("unable to execute %r for unknown reasons" % cmd)
    os._exit(1)

请注意，如果在OSError块中引发try，我们将退出系统状态为1（失败）。
请注意，即使OSError 不引发，我们仍退出系统状态为1（失败）。
在这两种情况下，一直等待孩子完成的父进程会引发DistutilsExecError。

有人可以指出我的错误吗？或者我碰巧使用distutils的版本和一个已修复的疯狂错误？

Answer 1

啊哈，好的，docs说os.execvp和其他os.exec函数

这些功能都执行新程序，替换当前进程;他们不回来。 在Unix上，新的可执行文件被加载到当前进程，并且将具有与调用者相同的进程ID。错误将报告为OSError异常。

因此，一旦调用exec_fn，如果成功，则后续行将永远不会执行。它们已被新的os.execvp进程取代。

distutils中的_spawn_posix是否总会引发错误？

1 个答案: