linux文件拷贝（进程方法）

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文件拷贝，父进程拷贝该文件的前一半，子进程拷贝后一半

/*************************************************************************> File Name: work.c> Author: XXDK> Email: v.manstein@qq.com > Created Time: Wed 15 Mar 2017 01:41:55 AM PDT ************************************************************************/#include<stdio.h>#include<sys/stat.h>#include<unistd.h>#include<stdlib.h>#include<sys/wait.h>#include<fcntl.h>int main(int argc, const char *argv[]){char buf[32] = {0};int fsrc, fdest;int file_len = 0;int file_len_half = 0;int ret = 0;int count = 0;int count_rmd = 0;pid_t pid;if(argc < 3) {perror("wokao");exit(-1);}fsrc = open(argv[1], O_RDONLY);if(fsrc < 0) {perror("open src error");exit(-1);}fdest = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC);if(fdest < 0) {close(fsrc);perror("open dest error");exit(-1);}printf("ready!\n");file_len = lseek(fsrc, 0, SEEK_END);file_len_half = file_len / 2;count_rmd = file_len_half % sizeof(buf);// 计算最后一次拷贝几个字节count = file_len_half / sizeof(buf);// 计算需要拷贝多少个32次printf("file length: %d bytes, file half lenght: %d\n", file_len, file_len/2);//-----------------------------------------------------------------------------if((pid = fork()) == 0) {// child processint i;lseek(fdest, file_len_half, SEEK_SET);lseek(fsrc, file_len_half, SEEK_SET);while(1) {ret = read(fsrc, buf, sizeof(buf));i++;if(count == i) {ret = read(fsrc, buf, count_rmd);}write(fdest, buf, ret);if(count == i)break;}close(fdest);close(fsrc);} else if(pid > 0) { // parent processint i = 0;lseek(fsrc, 0, SEEK_SET);while(1) {ret = read(fsrc, buf, sizeof(buf));i++;if(count == i) {ret = read(fsrc, buf, count_rmd);}write(fdest, buf, ret);if(count == i)break;}waitpid(-1, NULL, 0);} else {perror("fuck error");close(fdest);close(fsrc);exit(-1);}exit(0);}

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