}
-/* 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 */
-struct map_struct *map_file(int fd, OFF_T len, size_t block_size)
+/* 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. */
+struct map_struct *map_file(int fd, OFF_T len, OFF_T map_size,
+ int32 blk_size)
{
struct map_struct *map;
if (!(map = new(struct map_struct)))
out_of_memory("map_file");
+ if (blk_size && (map_size % blk_size))
+ map_size += blk_size - (map_size % blk_size);
+
memset(map, 0, sizeof map[0]);
map->fd = fd;
map->file_size = len;
- map->def_window_size = MAX(MAX_MAP_SIZE, block_size * 32);
+ map->def_window_size = map_size;
return map;
}
/* slide the read window in the file */
-char *map_ptr(struct map_struct *map,OFF_T offset,int len)
+char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
{
int nread;
OFF_T window_start, read_start;
return NULL;
/* can't go beyond the end of file */
- if (len > (map->file_size - offset)) {
+ if (len > map->file_size - offset)
len = map->file_size - offset;
- }
/* in most cases the region will already be available */
- if (offset >= map->p_offset &&
- offset+len <= map->p_offset+map->p_len) {
- return (map->p + (offset - map->p_offset));
- }
+ if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
+ return map->p + (offset - map->p_offset);
/* nope, we are going to have to do a read. Work out our desired window */
- if (offset > 2*CHUNK_SIZE) {
- window_start = offset - 2*CHUNK_SIZE;
- window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
- } else {
- window_start = 0;
- }
+ window_start = offset;
window_size = map->def_window_size;
if (window_start + window_size > map->file_size) {
window_size = map->file_size - window_start;
}
- if (offset + len > window_start + window_size) {
+ if (offset + len > window_start + window_size)
window_size = (offset+len) - window_start;
- }
/* make sure we have allocated enough memory for the window */
if (window_size > map->p_size) {