Function map_file

fileio.c:218–232

This provides functionality somewhat similar to mmap() but using read(). * It gives sliding window access to a file. mmap() is not used because of * the possibility of another program (such as a mailer) truncating the * file thus giving us a SIGBUS. */

 * the possibility of another program (such as a mailer) truncating the
 * file thus giving us a SIGBUS. */
struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
{
	struct map_struct *map;

	map = new0(struct map_struct);

	if (blk_size && (read_size % blk_size))
		read_size += blk_size - (read_size % blk_size);

	map->fd = fd;
	map->file_size = len;
	map->def_window_size = ALIGNED_LENGTH(read_size);

	return map;
}


/* slide the read window in the file */