linux开发---30.【C】实现内存替换

1. linux开发---30.【C】实现内存替换

2. 代码如下

cong@msi:/work/cloud/test2$ cat test.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <zlib.h>

#define dbmsg(fmt, args ...) printf("%s:%s[%d]: "fmt"\n", __FILE__,__FUNCTION__, __LINE__,##args)
int memstr_my(unsigned char* src, int src_len, int start_pos)
{
    int i;
    unsigned char search[10] = {0,0,0,0,0,0,0,0,0,0};
    int search_len = 10;
    for(i=start_pos; i<src_len; i++)
    {
        if(0 == memcmp(&src[i], search, search_len))
            break;
    }
    if(i==src_len)
        return -1;
    return i;
}

void mem_substitute(unsigned char *src, int src_len, unsigned char *dst, int dst_len)
{
    unsigned char *pi, *po;
    int search_len, left_len;
    int pos;
    pi = src;
    po = dst;
    search_len = 10;
    pos = memstr_my(pi, src_len, 0);
    left_len = src_len;
    if(pos > 0)
    {
        while(pos > 0 )
        {
            memcpy(po, pi, pos);
            pi += pos + search_len;
            po += pos;
            left_len -= pos;
            left_len -= search_len;
            pos = memstr_my(pi, left_len, pos);
        }
        memcpy(po, pi, left_len);
    }
    else
    {
        //if not found, just copy
        memcpy(po, pi, src_len);
    }
}

int main(int ac, char *av[])
{
    int i;
    unsigned char src[128];
    unsigned char dst[128];
    for(i=0; i<128; i++)
        src[i] = i%128;

    for(i=0; i<10; i++)
        src[i+12] = 0;

    for(i=0; i<10; i++)
        src[i+48] = 0;

    mem_substitute(src, 128, dst, 128);
    for(i=0; i<128; i++)
    {
        printf("%d=0x%x  ", i, dst[i]);
        if((i+1)%10 == 0)
            printf("\n");
    }
    printf("\n");
    return 0;
}
cong@msi:/work/cloud/test2$

3. 代码下载
mem_substitute.rar(下载后改名为mem_substitute.rar)