python 读取共享内存

测试环境 centos7 python3.6.5

首先使用c创建内存，这里的方法是：作为参数读一个二进制数据文件进去，把文件的内容作为共享内存的内容

定义块

#include <stdio.h>

#include <sys/shm.h>

#include <string.h>

int main(int argc, char *argv[])

{

    int        id = ;

    char    *data = NULL;

    FILE    *fp = NULL;

    int        totle_len = ;

    int        len = ;

    char    buf[] = {};

    if (argc < )

    {

        printf("args too less\n");

        return ;

    }

    id = shmget(,  *  * , IPC_CREAT | );

    if (id < )

    {

        printf("get id failed\n");

        return ;

    }

    data = shmat(id, NULL, );

    if (data == NULL)

    {

        printf("shamt failed\n");

        return ;

    }

    fp = fopen(argv[], "rb");

    if (fp == NULL)

    {

        printf("open %s failed\n", argv[]);

        return ;

    }

    while (totle_len <=  +  *  * )

    {

        len = fread(buf, , , fp);

        if (len <= )

        {

            break;

        }

        memcpy(data + totle_len, buf, len);

        totle_len += len;

    }

fclose(fp);

    return ;

}

使用python读取：

from ctypes import *

import numpy as npimport codecs

import datetime

SHM_SIZE = 1024*1024*20

SHM_KEY = 123559

OUTFILE="httpd_cdorked_config.bin"

try:

    rt = CDLL('librt.so')

except:

    rt = CDLL('librt.so.1')

shmget = rt.shmget

shmget.argtypes = [c_int, c_size_t, c_int]

shmget.restype = c_int

shmat = rt.shmat

shmat.argtypes = [c_int, POINTER(c_void_p), c_int]

shmat.restype = c_void_p

shmid = shmget(SHM_KEY, SHM_SIZE, 0o666)

if shmid < 0:

    print ("System not infected")

else:

    begin_time=datetime.datetime.now()

    addr = shmat(shmid, None, 0)

    f=open(OUTFILE, 'wb')

    rate=int.from_bytes(string_at(addr,4), byteorder='little', signed=True)   #这里数据文件是小端int16类型

    len_a=int.from_bytes(string_at(addr+4,4), byteorder='little', signed=True)

    len_b=int.from_bytes(string_at(addr+8,4), byteorder='little', signed=True)

    print(rate,len_a,len_b)

    f.write(string_at(addr+12,SHM_SIZE))

    f.close()

#print ("Dumped %d bytes in %s" % (SHM_SIZE, OUTFILE))

print("Success!",datetime.datetime.now()-begin_time)

块的大小和块号可以设置，注意读取的时候 二进制文件的数据格式要保持一致否则读不出来正确的东西