1 /* 2 * General functionality supporting file paging. 3 * 4 * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #include "file_pager.h" 23 #include "file_paging.h" 24 25 #include <systypes/fcntl.h> 26 27 28 29 FilePaging::FilePaging(Pages *pages) 30 : _pages(pages) 31 { 32 } 33 34 35 36 /* Return any registered page mapper for the given 'fileid' or NULL if no such 37 mapper is registered. */ 38 39 PageMapper *FilePaging::get(fileid_t fileid) 40 { 41 FileMapping::iterator entry = _mappers.find(fileid); 42 PageMapper *mapper; 43 44 if (entry == _mappers.end()) 45 mapper = NULL; 46 else 47 mapper = entry->second; 48 49 return mapper; 50 } 51 52 /* Register a page 'mapper' for the given 'fileid'. */ 53 54 void FilePaging::set(fileid_t fileid, PageMapper *mapper) 55 { 56 FileMapping::iterator entry = _mappers.find(fileid); 57 58 if (entry == _mappers.end()) 59 _mappers[fileid] = mapper; 60 } 61 62 63 64 /* Convert opening flags to map-compatible paging flags. */ 65 66 flags_t FilePaging::get_flags(flags_t flags) 67 { 68 return flags & (O_WRONLY | O_RDWR) ? L4RE_DS_MAP_FLAG_RW : L4RE_DS_MAP_FLAG_RO; 69 } 70 71 72 73 /* Obtain a page mapper for the 'fileid' or register a new one in the 74 paging object. */ 75 76 PageMapper *FilePaging::get_mapper(fileid_t fileid) 77 { 78 /* Obtain any registered page mapper. */ 79 80 PageMapper *mapper = get(fileid); 81 82 if (mapper != NULL) 83 return mapper; 84 85 /* Make an accessor and page mapper, registering the mapper. */ 86 87 Accessor *accessor = make_accessor(fileid); 88 mapper = new PageMapper(accessor, _pages); 89 90 set(fileid, mapper); 91 92 return mapper; 93 } 94 95 96 97 /* Return a pager initialised with a page mapper. */ 98 99 Pager *FilePaging::get_pager(fileid_t fileid, flags_t flags) 100 { 101 std::lock_guard<std::mutex> guard(_lock); 102 103 /* Initialise the pager with the mapper and a reference to this object for 104 closing the mapper and accessor. */ 105 106 PageMapper *mapper = get_mapper(fileid); 107 return new FilePager(fileid, mapper, flags, this); 108 } 109 110 /* Detach a pager, potentially removing its resources. */ 111 112 void FilePaging::detach_pager(fileid_t fileid, PageMapper *mapper) 113 { 114 std::lock_guard<std::mutex> guard(_lock); 115 116 if (!mapper->detach()) 117 { 118 _mappers.erase(fileid); 119 delete mapper->accessor(); 120 delete mapper; 121 } 122 } 123 124 // vim: tabstop=4 expandtab shiftwidth=4