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 FilePaging::~FilePaging() 35 { 36 } 37 38 39 40 /* Return any registered page mapper for the given 'fileid' or NULL if no such 41 mapper is registered. */ 42 43 PageMapper *FilePaging::get(fileid_t fileid) 44 { 45 FileMapping::iterator entry = _mappers.find(fileid); 46 PageMapper *mapper; 47 48 if (entry == _mappers.end()) 49 mapper = NULL; 50 else 51 mapper = entry->second; 52 53 return mapper; 54 } 55 56 /* Register a page 'mapper' for the given 'fileid'. */ 57 58 void FilePaging::set(fileid_t fileid, PageMapper *mapper) 59 { 60 FileMapping::iterator entry = _mappers.find(fileid); 61 62 if (entry == _mappers.end()) 63 _mappers[fileid] = mapper; 64 } 65 66 67 68 /* Convert opening flags to map-compatible paging flags. */ 69 70 flags_t FilePaging::get_flags(flags_t flags) 71 { 72 return flags & (O_WRONLY | O_RDWR) ? L4RE_DS_MAP_FLAG_RW : L4RE_DS_MAP_FLAG_RO; 73 } 74 75 76 77 /* Obtain a page mapper for the 'fileid' or register a new one in the 78 paging object. */ 79 80 PageMapper *FilePaging::get_mapper(fileid_t fileid) 81 { 82 /* Obtain any registered page mapper. */ 83 84 PageMapper *mapper = get(fileid); 85 86 if (mapper != NULL) 87 return mapper; 88 89 /* Make an accessor and page mapper, registering the mapper. */ 90 91 Accessor *accessor = make_accessor(fileid); 92 mapper = new PageMapper(accessor, _pages); 93 94 set(fileid, mapper); 95 96 return mapper; 97 } 98 99 100 101 /* Return a pager initialised with a page mapper. */ 102 103 Pager *FilePaging::get_pager(fileid_t fileid, flags_t flags) 104 { 105 std::lock_guard<std::mutex> guard(_lock); 106 107 /* Initialise the pager with the mapper and a reference to this object for 108 closing the mapper and accessor. */ 109 110 PageMapper *mapper = get_mapper(fileid); 111 return new FilePager(fileid, mapper, flags, this); 112 } 113 114 /* Detach a pager, potentially removing its resources. */ 115 116 void FilePaging::detach_pager(fileid_t fileid, PageMapper *mapper) 117 { 118 std::lock_guard<std::mutex> guard(_lock); 119 120 if (!mapper->detach()) 121 { 122 _mappers.erase(fileid); 123 delete mapper->accessor(); 124 delete mapper; 125 } 126 } 127 128 // vim: tabstop=4 expandtab shiftwidth=4