linux 的cp命令实现

最近苦读《Unix系统编程》便写了一些实例，逐步增加自己Unix程序设计的能力。

首先来实现一个Unix下常用命令：cp

先看代码：

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>

#define BUFSIZE 512
#define PERM 0755

/* copy file function */
int copyfile(const char *name1, const char *name2)
{
int infile, outfile;
ssize_t nread;
char buffer[BUFSIZE];
/* 打开源文件 */
if ((infile = open(name1, O_RDONLY)) == -1)
return (-1);
/* 打开目标文件 */
if ((outfile = open(name2, O_WRONLY|O_CREAT|O_TRUNC, PERM)) == -1)
{
close(infile);
return (-2);
}
/* 循环的把源文件写入目标文件 */
while ((nread = read(infile, buffer, BUFSIZE)) > 0)
{
if (write(outfile, buffer, nread) < nread)
{
close(infile);
close(outfile);
return (-3);
}
}
/* 关闭资源 */
close(infile);
close(outfile);

if (nread == -1)
return (-4);
else
return (0);
}

main(int argc, char *argv[])
{
/* 判断提交的参数 */
if (argc != 3) {
printf("Usage: copyfile <file1> <file2>/n");
exit(1);
}
char *file1, *file2;
file1 = argv[1];
file2 = argv[2];
int retcode;
/* 进行复制 */
retcode = copyfile(file1, file2);
/* 错误信息控制 */
if (retcode == -1) {
printf("Open %s failed/n", file1);
exit(1);
}
if (retcode == -2) {
printf("Open %s failed/n", file2);
exit(1);
}
if (retcode == -3) {
printf("Read %s buffer failed/n", file1);
exit(1);
}
if (retcode == -4) {
printf("Write %s buffer failed/n", file2);
exit(1);
}

if (retcode == 0) {
printf("Copy file succeed!/n");
}
}