1 /*
  2  * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 package jdk.internal.foreign;
 27 
 28 import jdk.incubator.foreign.MemoryAccess;
 29 import jdk.incubator.foreign.MemorySegment;
 30 import jdk.incubator.foreign.ResourceScope;
 31 import jdk.incubator.foreign.SymbolLookup;
 32 import jdk.incubator.foreign.MemoryAddress;
 33 import jdk.internal.loader.NativeLibraries;
 34 import jdk.internal.loader.NativeLibrary;
 35 
 36 import java.nio.file.Files;
 37 import java.nio.file.Path;
 38 import java.util.Objects;
 39 import java.util.Optional;
 40 import java.util.function.Function;
 41 
 42 import static jdk.incubator.foreign.CLinker.C_POINTER;
 43 
 44 public class SystemLookup implements SymbolLookup {
 45 
 46     private SystemLookup() { }
 47 
 48     final static SystemLookup INSTANCE = new SystemLookup();
 49 
 50     /*
 51      * On POSIX systems, dlsym will allow us to lookup symbol in library dependencies; the same trick doesn't work
 52      * on Windows. For this reason, on Windows we do not generate any side-library, and load msvcrt.dll directly instead.
 53      */
 54     private static final SymbolLookup syslookup = switch (CABI.current()) {
 55         case SysV, LinuxAArch64, MacOsAArch64 -> libLookup(libs -> libs.loadLibrary("syslookup"));
 56         case Win64 -> makeWindowsLookup(); // out of line to workaround javac crash
 57     };
 58 
 59     private static SymbolLookup makeWindowsLookup() {
 60         Path system32 = Path.of(System.getenv("SystemRoot"), "System32");
 61         Path ucrtbase = system32.resolve("ucrtbase.dll");
 62         Path msvcrt = system32.resolve("msvcrt.dll");
 63 
 64         boolean useUCRT = Files.exists(ucrtbase);
 65         Path stdLib = useUCRT ? ucrtbase : msvcrt;
 66         SymbolLookup lookup = libLookup(libs -> libs.loadLibrary(null, stdLib.toFile()));
 67 
 68         if (useUCRT) {
 69             // use a fallback lookup to look up inline functions from fallback lib
 70 
 71             SymbolLookup fallbackLibLookup = libLookup(libs -> libs.loadLibrary("WinFallbackLookup"));
 72 
 73             int numSymbols = WindowsFallbackSymbols.values().length;
 74             MemorySegment funcs = fallbackLibLookup.lookup("funcs").orElseThrow()
 75                 .asSegment(C_POINTER.byteSize() * numSymbols, ResourceScope.newImplicitScope());
 76 
 77             SymbolLookup fallbackLookup = name -> Optional.ofNullable(WindowsFallbackSymbols.valueOfOrNull(name))
 78                 .map(symbol -> MemoryAccess.getAddressAtIndex(funcs, symbol.ordinal()));
 79 
 80             final SymbolLookup finalLookup = lookup;
 81             lookup = name -> finalLookup.lookup(name).or(() -> fallbackLookup.lookup(name));
 82         }
 83 
 84         return lookup;
 85     }
 86 
 87     private static SymbolLookup libLookup(Function<NativeLibraries, NativeLibrary> loader) {
 88         NativeLibrary lib = loader.apply(NativeLibraries.rawNativeLibraries(SystemLookup.class, false));
 89         return name -> {
 90             Objects.requireNonNull(name);
 91             try {
 92                 long addr = lib.lookup(name);
 93                 return addr == 0 ?
 94                         Optional.empty() : Optional.of(MemoryAddress.ofLong(addr));
 95             } catch (NoSuchMethodException e) {
 96                 return Optional.empty();
 97             }
 98         };
 99     }
100 
101     @Override
102     public Optional<MemoryAddress> lookup(String name) {
103         return syslookup.lookup(name);
104     }
105 
106     public static SystemLookup getInstance() {
107         return INSTANCE;
108     }
109 
110     // fallback symbols missing from ucrtbase.dll
111     // this list has to be kept in sync with the table in the companion native library
112     private enum WindowsFallbackSymbols {
113         // stdio
114         fprintf,
115         fprintf_s,
116         fscanf,
117         fscanf_s,
118         fwprintf,
119         fwprintf_s,
120         fwscanf,
121         fwscanf_s,
122         printf,
123         printf_s,
124         scanf,
125         scanf_s,
126         snprintf,
127         sprintf,
128         sprintf_s,
129         sscanf,
130         sscanf_s,
131         swprintf,
132         swprintf_s,
133         swscanf,
134         swscanf_s,
135         vfprintf,
136         vfprintf_s,
137         vfscanf,
138         vfscanf_s,
139         vfwprintf,
140         vfwprintf_s,
141         vfwscanf,
142         vfwscanf_s,
143         vprintf,
144         vprintf_s,
145         vscanf,
146         vscanf_s,
147         vsnprintf,
148         vsnprintf_s,
149         vsprintf,
150         vsprintf_s,
151         vsscanf,
152         vsscanf_s,
153         vswprintf,
154         vswprintf_s,
155         vswscanf,
156         vswscanf_s,
157         vwprintf,
158         vwprintf_s,
159         vwscanf,
160         vwscanf_s,
161         wprintf,
162         wprintf_s,
163         wscanf,
164         wscanf_s,
165 
166         // time
167         gmtime
168         ;
169 
170         static WindowsFallbackSymbols valueOfOrNull(String name) {
171             try {
172                 return valueOf(name);
173             } catch (IllegalArgumentException e) {
174                 return null;
175             }
176         }
177     }
178 }