//Linux文件编程 — — 系统文件调用中的file_cp.c
//待修改。。。

 1 #include <stdio.h> 2 #incldue <sys/stat.h> 3 #include <fcntl.h> 4 #include <errno.h> 5  6 #define BUFFSIZE 1024 7  8 int main(int argc, char *argv[]) 9 {10     int from_fd, to_fd;11     int bytes_read, bytes_write;12     char buffer[BUFFSIZE];13     char *ptr;14 15     if(argc != 3)16     {17         fprintf(stderr, "Usage: %s from_file to_file\n", argv[0]);18         exit(EXIT_FAILURE); 19     }20 21 //open from_file22     if((from_fd = open(argv[1], O_RDONLY)) == -1)23     {24         fprintf(stderr, "Open %s ERROR:%s\n", argv[1], strerror(errno));25         exit(EXIT_FAILURE);26     }27 //creat to_file28     if((to_fd = open(argv[2], O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR)) == -1)29     {30     　　 fprintf(stderr, "Open %s ERROR:%s", argv[2], strerror(errno));31　　　    exit(EXIT_FAILURE);32     }33 34 //经典的拷贝文件代码35     while(bytes_read = read(from_fd, buffer, BUFFSIZE))36     {37     if((bytes_read == -1) && (errno != EINTR)) break;38     else if(bytes_read > 0)39     {40         ptr = buffer;41         while(bytes_write = write(to_file, buffer, bytes_read))42         {43          //发生了一个致命的错误44         if((bytes_write == -1) && (errno != EINTR)) break;45         //写完了所有读的字节46         else if(bytes_write == bytes_read) break;47         //只写了一部分，继续写48         else if(bytes_write > 0)49         {50             ptr += bytes_write;51             bytes_read -= bytes_write;   52         }53         }54         //写的时候发生了错误55         if(bytes_write == -1) break;56     }57     }58     close(from_fd);59     close(to_fd);60     exit(0);61 }