- /* align the mmap region on a nice boundary back a bit from
- where it is asked for to allow for some seeking */
- if (offset > 2*CHUNK_SIZE) {
- map->p_offset = offset - 2*CHUNK_SIZE;
- map->p_offset &= ~((OFF_T)(CHUNK_SIZE-1));
- } else {
- map->p_offset = 0;
- }
-
- /* map up to MAX_MAP_SIZE */
- map->p_len = MAX(len, MAX_MAP_SIZE);
- map->p_len = MIN(map->p_len, map->size - map->p_offset);
-
- map->map = (char *)do_mmap(NULL,map->p_len,PROT_READ,
- MAP_SHARED,map->fd,map->p_offset);
-
- if (map->map == (char *)-1) {
- map->map = NULL;
- map->p_len = 0;
- map->p_offset = 0;
- } else {
- return (map->map + (offset - map->p_offset));
- }
- }
-#endif
+/* slide the read window in the file */
+char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
+{
+ int32 nread;
+ OFF_T window_start, read_start;
+ int32 window_size, read_size, read_offset;