多进程拷贝数据文件

多进程拷贝数据

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
int mmap_mamcpy(char **argv)
{
    int fp=open(argv[1],O_RDONLY);
    if(fp<0)
    {
        printf("文件打开失败\n");
        return 0;
    }
    int new_fp=open(argv[2],O_RDWR|O_CREAT,0666);
    if(new_fp<0)
    {
        printf("新文件打开失败\n");
        return 0;
    }
    //计算文件大小
    struct stat buf;
    fstat(fp,&buf);
    if (buf.st_size<=0) return 0;
    //设置新文件大小
    ftruncate(new_fp,buf.st_size);
    //文件映射
    unsigned char *str_fp=mmap(NULL,buf.st_size,PROT_READ,MAP_SHARED,fp,0);
    close(fp);
    if(str_fp==(void *)-1)
    {
        printf("文件映射失败\n");
        return 0;
    }
    //文件映射
    unsigned char *str_new_fp=mmap(NULL,buf.st_size,PROT_READ|PROT_WRITE,MAP_SHARED,new_fp,0);
    close(new_fp);
    if(str_new_fp==(void *)-1)
    {
        printf("新文件映射失败\n");
        return 0;
    }
    int size=buf.st_size/5;    //平均分配每个子进程拷贝的大小
    int father_size=buf.st_size%5;
    int i=0;
    for(i=0;i<5;i++)
    {
        if(fork()==0)   break;;
    }
    if (i<5)
    {
        memcpy(str_new_fp+i*size,str_fp+i*size,size);
    }
    else
    {
        if(father_size>0)
        {
            memcpy(str_new_fp+i*size,str_fp+i*size,size);
        }
        pid_t pid;
        while(1)
        {
            pid=wait(NULL);
            if(pid<0)
                break;
            printf("%d子进程拷贝成功\n",pid);
        }
        munmap(str_new_fp,buf.st_size);
        munmap(str_fp,buf.st_size);
    }
}
int main(int argc, char **argv)
{
    if(argc!=3)
    {
        printf("请输入<.\a.out> [文件1] [文件2]\n");
        return 0;
    }
    mmap_mamcpy(argv);
    return 0;
}