#include <stdio.h>

 #include <string.h>

 #include <sys/types.h>

 #include <sys/stat.h>

 #include <unistd.h>

 #include <fcntl.h>

 #include <sys/mman.h>

 #define COFYMODE 0666

 int copy(const char* src, const char* dest)

 {

     int ret = -;

     int in_fd = -, out_fd = -;

     size_t filesize;

     char nullbyte;

     void *source_addr = NULL;

     void *dest_addr = NULL;

     /* check args */

     if(src == NULL || dest == NULL){

         fprintf(stderr,"file path can not be null\n");

         return ret;

     }

     /* open files */

     if((in_fd=open(src, O_RDONLY))==-) {

         fprintf(stderr, "Cannot open %s\n", src);

         return ret;

     }

 #if defined(i386) || defined(__x86_64) || defined(__x86_64__) || defined(i686)

     if((out_fd=open(dest, O_RDWR|O_CREAT|O_TRUNC,COFYMODE))==-)

     {

         fprintf(stderr, "Cannot open %s\n", dest);

         ret = -;

         goto cleanup;

     }

 #else

     if((out_fd=open(dest, O_WRONLY|O_CREAT|O_TRUNC,COFYMODE))==-)

     {

         fprintf(stderr, "Cannot create %s\n", dest);

         ret = -;

         goto cleanup;

     }

 #endif

    if((filesize=lseek(in_fd,,SEEK_END))==-)

    {

        fprintf(stderr, "Could not seek to end of file %s\n", src);

         ret = -;

         goto cleanup;

    }

    if(filesize == )

    {

        ret = ;

        goto cleanup;

    }

     lseek(out_fd,filesize-,SEEK_SET);

     write(out_fd,&nullbyte,);

     /* setup the memory maps */

     if((source_addr=mmap(NULL,filesize,PROT_READ,MAP_SHARED,in_fd,))==(void *)-)

     {

         fprintf(stderr, "Error mapping file %s\n", src);

         ret = -;

         goto cleanup;

     }

     if((dest_addr=mmap(NULL,filesize,PROT_WRITE,MAP_SHARED,out_fd,))==(void *)-)

     {

         fprintf(stderr, "Error mapping file %s\n", dest);

         ret = -;

         goto cleanup;

     }

     /* copy the input to output by doing a memcpy */

     memcpy(dest_addr,source_addr,filesize);

 cleanup:

     /*unmap the fiels */

     if(source_addr) munmap(source_addr,filesize);

     if(dest_addr) munmap(dest_addr,filesize);

     /* close the files */

     if(in_fd > )close(in_fd);

     if(out_fd > ) close(out_fd);

     return ret;

 }

 int main(int argc, char* argv[])

 {

     if(argc < )

     {

         fprintf(stderr, "useage: %s src_file dest_file", argv[]);

         return -;

     }

     return copy(argv[], argv[]);

 }