Python子进程挂起

Question

我正在执行以下子进程...

p.call(["./hex2raw", "<", "exploit4.txt", "|", "./rtarget"])

...它挂了。

但是如果我执行kmwe236@kmwe236:~/CS485/prog3/target26$ ./hex2raw < exploit4.txt | ./rtarget 那么它执行得很好。使用输入或管道操作符有什么问题吗？

我也试过sp.call(["./hex2raw", "<", "exploit4.txt", "|", "./rtarget"], shell=True)

整个代码如下所示UPDATED WITH SUGGESTIONS

import subprocess as sp
import pdb

for i in range(4201265,4201323):
    pdb.set_trace()
    d = hex(i)[2:]
    output = " "
    for i in range(len(d),0,-2):
        output = output + d[i-2:i] + " "

    out_buffer = "00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00" + output + "00 00 00 00"

    text_file = open("exploit4.txt", "w")
    text_file.write("%s" % out_buffer)

 #   sp.call(["./hex2raw", "<", "exploit4.txt", "|", "./rtarget"], shell=True)
    with open("exploit4.txt") as inhandle:
        p = sp.Popen("./hex2raw",stdin=inhandle,stdout=sp.PIPE)
        p2 = sp.Popen("./rtarget",stdin=p.stdout,stdout=sp.PIPE)
        [output,error] = p2.communicate()

我得到一个错误是

  File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
    raise child_exception
OSError: [Errno 8] Exec format error

调试后发生在触发子进程调用p = sp.Popen("./hex2raw",stdin=inhandle,stdout=sp.PIPE)

Answer 1

由于您使用重定向和管道，您必须启用shell=True

sp.call(["./hex2raw", "<", "exploit4.txt", "|", "./rtarget"],shell=True)

但是在两个可执行文件上使用Popen 并输入exploit4.txt 的内容作为输入会更简洁。以下示例，适用于您的情况：

import subprocess

    with open("exploit4.txt") as inhandle:
        p = subprocess.Popen("./hex2raw",stdin=inhandle,stdout=subprocess.PIPE)
        p2 = subprocess.Popen("./rtarget",stdin=p.stdout,stdout=subprocess.PIPE)
        [output,error] = p2.communicate()
        print(output)
        # checking return codes is also a good idea
        rc2 = p2.wait()
        rc = p.wait()

解释：

1. 打开输入文件，获取其句柄inhandle
2. 打开第一个子进程，将stdin 和inhandle 和stdout 重定向到输出流。获取管道句柄 (p)
3. 打开第二个子进程，将 stdin 与前一个进程 stdout 和 stdout 重定向到输出流
4. 让第二个进程communicate。它将通过消耗其输出来“拉”第一个：两个进程都以管道方式工作
5. 获取返回码并打印结果

注意：您会收到“格式错误”，因为一个或两个可执行文件实际上是 shell 或其他非本机可执行文件。在这种情况下，只需将shell=True 选项添加到相关的Popen 调用中即可。