参数的ctypes错误

ctypes Errors with argv

本文关键字：错误 ctypes 参数      更新时间：2023-10-16

我正试图用类型从python调用我的C++库，但我不能作为IP参数和HEX代码传递，有人能帮我吗？

import sys 
import ctypes 
lib = ctypes.CDLL('./hello.so') 
LP_c_char = ctypes.POINTER(ctypes.c_char) 
LP_LP_c_char = ctypes.POINTER(LP_c_char) 
lib.connect_pe_func.argtypes = (ctypes.c_int, LP_LP_c_char)  
argc = 2
argv = ["192.168.2.170","2600000026"]
for i, arg in enumerate(sys.argv): 
enc_arg = arg.encode('utf-8') 
argv[i] = ctypes.create_string_buffer(enc_arg) 
lib.connect_pe_func(argc, argv)

这是错误消息，如何在不出现此错误的情况下将IP和Hex代码插入argv矢量？

---------------------------------------------------------------------------
ArgumentError                             Traceback (most recent call last)
<ipython-input-21-f59eabe02690> in <module>
17   argv[i] = ctypes.create_string_buffer(enc_arg)
18
---> 19 lib.connect_pe_func(argc, argv)
ArgumentError: argument 2: <class 'TypeError'>: expected LP_LP_c_char instance instead of list

为了完整起见，我还插入了我编译并制作成hello.so库的C++代码

#include <stdio.h>
#include <errno.h>
#include <string>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <cstring>
#include <unistd.h>
#include <iostream>
#include <unistd.h>
#include <sstream>
#include "connect_PE_func.h"
using namespace std;

extern "C" char * connect_pe_func(int argc, char *argv[])
{
int sockfd, n;
int connected = 0;
struct sockaddr_in servaddr;
std::string serveraddr = argv[1];
sockfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr(serveraddr.c_str());
servaddr.sin_port = htons(9761);
connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
std::string pref_hex;
std::string hex("0x");
std::string test = argv[2];
size_t numbytes = test.size() / 2;
uint8_t command[numbytes];
for (size_t w = 0, x = 0; w < numbytes; ++w, x += 2)
{
pref_hex = hex + test.substr(x, 2);
cout << pref_hex;
command[w] = stoi(pref_hex, nullptr, 16);
}
int bytes_to_send = sizeof(command);
send(sockfd, command, bytes_to_send, 0);
uint8_t output_command[numbytes];
recv(sockfd, output_command, bytes_to_send, 0);
char test_out[10];
for (size_t w = 0, x = 0; w < numbytes; ++w, x += 2)
{
test_out[x] = (char)output_command[w];
}
return test_out;
};
extern "C" char * hello_world(char * name){
char * output = (char *) calloc(sizeof(name)+7, sizeof(char));
strcat(output, "Hello ");
strcat(output, name);
strcat(output, "");
//output[sizeof(output)-1] = '/0';
return output;
};

Python列表不能作为指针的指针传递。

要从Python创建和填充指针的指针，您需要：

  • 创建指针数组:p = (LP_c_char*len(argv))()(为指针分配空间(
  • 将转换为指针的指针：na = ctypes.cast(p, LP_LP_c_char)(使其与指针形式的衰退指针兼容(

或没有重新定义：

p = (ctypes.POINTER(ctypes.c_char)*len(argv))()
na = ctypes.cast(p, ctypes.POINTER(ctypes.POINTER(ctypes.c_char)))

固定代码：

import sys
import ctypes
lib = ctypes.CDLL('./hello.so')
LP_c_char = ctypes.POINTER(ctypes.c_char)
LP_LP_c_char = ctypes.POINTER(LP_c_char)
lib.connect_pe_func.argtypes = (ctypes.c_int, LP_LP_c_char)
argv = ["192.168.2.170","2600000026"]
argc = len(argv)
p = (LP_c_char*len(argv))()
for i, arg in enumerate(argv):  # not sys.argv, but argv!!!
enc_arg = arg.encode('utf-8')
p[i] = ctypes.create_string_buffer(enc_arg)
na = ctypes.cast(p, LP_LP_c_char)
lib.connect_pe_func(argc, na)

为了测试这一点，我创建了一个非常简单的c++代码(而不是你的(

#include <stdio.h>
extern "C" char * connect_pe_func(int argc, char *argv[])
{
for (int i=0;i<argc;i++)
{
puts(argv[i]);
}
return 0;
}

内置：g++ -shared -o hello.so test.cpp

运行python模块可以证明参数传递得很好：

192.168.2.170
2600000026

受Python ctypes 中指针和数组的启发

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