+char *map_ptr(char *buf,off_t offset,int len)
+{
+ if (buf)
+ return buf+offset;
+
+ if (len == 0)
+ return NULL;
+
+ len = MIN(len,map_size-offset);
+
+ if (offset >= p_offset &&
+ offset+len <= p_offset+p_len) {
+ return (p + (offset - p_offset));
+ }
+
+ len = MAX(len,WRITE_BLOCK_SIZE);
+ len = MIN(len,map_size - offset);
+
+ if (len > p_size) {
+ if (p) free(p);
+ p = (char *)malloc(len);
+ if (!p) out_of_memory("map_ptr");
+ p_size = len;
+ }
+
+ if (lseek(map_fd,offset,SEEK_SET) != offset ||
+ read(map_fd,p,len) != len) {
+ fprintf(stderr,"EOF in map_ptr!\n");
+ exit(1);
+ }
+
+ p_offset = offset;
+ p_len = len;
+
+ return p;
+}
+
+