1 /* 2 * A page mapper providing memory pages to satisfy file accesses, masking the 3 * limits of a visible region of the file's contents. 4 * 5 * Copyright (C) 2021, 2022 Paul Boddie <paul@boddie.org.uk> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; either version 2 of 10 * the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 20 * Boston, MA 02110-1301, USA 21 */ 22 23 #pragma once 24 25 #include <fsserver/generic_page_mapper.h> 26 #include <mem/memory_incremental.h> 27 28 29 30 /* A special flexpage class for masked flexpages. */ 31 32 class MaskedFlexpage : public Flexpage 33 { 34 public: 35 explicit MaskedFlexpage(Region *region = NULL); 36 }; 37 38 39 40 /* A file mapper, associating flexpages with file regions. */ 41 42 class MaskedPageMapper : public GenericPageMapper 43 { 44 protected: 45 GenericPageMapper *_mapper; 46 offset_t _size; 47 48 /* Masked region support. */ 49 50 MemoryIncremental _memory; 51 offset_t _start_visible, _end_visible; 52 MaskedFlexpage _start_flexpage, _end_flexpage, _zero_flexpage; 53 54 /* Internal flexpage retrieval methods. */ 55 56 Flexpage *get_masked_flexpage(Flexpage *flexpage); 57 58 void allocate_region(Flexpage *flexpage, Flexpage &masked); 59 60 void populate_region(Flexpage *flexpage, Flexpage &masked, 61 bool has_start, bool has_end); 62 63 public: 64 explicit MaskedPageMapper(GenericPageMapper *mapper, offset_t start_visible, 65 offset_t end_visible); 66 67 virtual ~MaskedPageMapper(); 68 69 /* Interface for the pager, implementing GenericPageMapper. */ 70 71 Flexpage *get(offset_t offset, map_flags_t flags); 72 73 void queue(Flexpage *flexpage); 74 75 void flush_all(offset_t start, offset_t size); 76 77 offset_t get_data_size(); 78 79 void set_data_size(offset_t size); 80 }; 81 82 // vim: tabstop=4 expandtab shiftwidth=4