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