POSIX GNU/Linux efficient copy file.

file_copy.c

/**
 * Copy the 'source' file to 'dest'. If 'dest' exists it will be 
 * overwritten.
 * 
 * @param source Path to the source file.
 * @param dest Path to the destination file.
 * @return Number of bytes copied or -1 if cannot copy 
 * file.
 */
int file_copy(char * source, char * dest)
{
	int fd_input, fd_output, rval;
	off_t n_bytes = 0;
	struct stat s_stat = {0};
	
	if ((fd_input = open(source, O_RDONLY)) == -1)
	{
		return -1;
	}
	if ((fd_output = creat(dest, 0660)) == -1)
	{
		close(fd_input);
		return -1;
	}
	
	fstat(fd_input, &s_stat);
	rval = sendfile(fd_output, fd_input, &n_bytes, s_stat.st_size);

	close(fd_input);
	close(fd_output);

	return rval;
}