Linux文件复制

#include <stdio.h>
#include <stdlib.h>


#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>




#define BUFFER_SIZE 1024


int main(int argc,char *argv[])
{
int from_fd;
int to_fd;
int bytes_read;
int bytes_write;


char buffer[BUFFER_SIZE];
char *ptr;




if(argc != 3)
{
printf("error");
exit(1);
}
if((from_fd = open(argv[1],O_RDONLY)) == -1)
{
printf("from file open failure\n");
exit(1);
}


if((to_fd = open(argv[2],O_WRONLY | O_CREAT,S_IRUSR | S_IWUSR)) == -1)
{
printf("to_file open failure\n");
exit(1);
}
while(bytes_read = read(from_fd,buffer,BUFFER_SIZE))
{
if( (bytes_read == -1))break;
else if(bytes_read > 0)
{
ptr = buffer;
while(bytes_write = write(to_fd,ptr,bytes_read))
{
if(bytes_write == -1)break;
else if(bytes_write == bytes_read) break;
else if(bytes_write > 0)
{
ptr += bytes_write;
bytes_read -= bytes_write;
}
}
if(bytes_write == -1)break;
}
}
close(from_fd);
close(to_fd);
exit(0);
}