1 //===- MinGW.cpp ----------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "MinGW.h" 10 #include "SymbolTable.h" 11 #include "lld/Common/ErrorHandler.h" 12 #include "llvm/Object/COFF.h" 13 #include "llvm/Support/Path.h" 14 #include "llvm/Support/raw_ostream.h" 15 16 using namespace llvm; 17 using namespace llvm::COFF; 18 19 namespace lld { 20 namespace coff { 21 22 AutoExporter::AutoExporter() { 23 excludeLibs = { 24 "libgcc", 25 "libgcc_s", 26 "libstdc++", 27 "libmingw32", 28 "libmingwex", 29 "libg2c", 30 "libsupc++", 31 "libobjc", 32 "libgcj", 33 "libclang_rt.builtins", 34 "libclang_rt.builtins-aarch64", 35 "libclang_rt.builtins-arm", 36 "libclang_rt.builtins-i386", 37 "libclang_rt.builtins-x86_64", 38 "libc++", 39 "libc++abi", 40 "libunwind", 41 "libmsvcrt", 42 "libucrtbase", 43 }; 44 45 excludeObjects = { 46 "crt0.o", "crt1.o", "crt1u.o", "crt2.o", "crt2u.o", "dllcrt1.o", 47 "dllcrt2.o", "gcrt0.o", "gcrt1.o", "gcrt2.o", "crtbegin.o", "crtend.o", 48 }; 49 50 excludeSymbolPrefixes = { 51 // Import symbols 52 "__imp_", 53 "__IMPORT_DESCRIPTOR_", 54 // Extra import symbols from GNU import libraries 55 "__nm_", 56 // C++ symbols 57 "__rtti_", 58 "__builtin_", 59 // Artificial symbols such as .refptr 60 ".", 61 }; 62 63 excludeSymbolSuffixes = { 64 "_iname", 65 "_NULL_THUNK_DATA", 66 }; 67 68 if (config->machine == I386) { 69 excludeSymbols = { 70 "__NULL_IMPORT_DESCRIPTOR", 71 "__pei386_runtime_relocator", 72 "_do_pseudo_reloc", 73 "_impure_ptr", 74 "__impure_ptr", 75 "__fmode", 76 "_environ", 77 "___dso_handle", 78 // These are the MinGW names that differ from the standard 79 // ones (lacking an extra underscore). 80 "_DllMain@12", 81 "_DllEntryPoint@12", 82 "_DllMainCRTStartup@12", 83 }; 84 excludeSymbolPrefixes.insert("__head_"); 85 } else { 86 excludeSymbols = { 87 "__NULL_IMPORT_DESCRIPTOR", 88 "_pei386_runtime_relocator", 89 "do_pseudo_reloc", 90 "impure_ptr", 91 "_impure_ptr", 92 "_fmode", 93 "environ", 94 "__dso_handle", 95 // These are the MinGW names that differ from the standard 96 // ones (lacking an extra underscore). 97 "DllMain", 98 "DllEntryPoint", 99 "DllMainCRTStartup", 100 }; 101 excludeSymbolPrefixes.insert("_head_"); 102 } 103 } 104 105 void AutoExporter::addWholeArchive(StringRef path) { 106 StringRef libName = sys::path::filename(path); 107 // Drop the file extension, to match the processing below. 108 libName = libName.substr(0, libName.rfind('.')); 109 excludeLibs.erase(libName); 110 } 111 112 bool AutoExporter::shouldExport(Defined *sym) const { 113 if (!sym || !sym->isLive() || !sym->getChunk()) 114 return false; 115 116 // Only allow the symbol kinds that make sense to export; in particular, 117 // disallow import symbols. 118 if (!isa<DefinedRegular>(sym) && !isa<DefinedCommon>(sym)) 119 return false; 120 if (excludeSymbols.count(sym->getName())) 121 return false; 122 123 for (StringRef prefix : excludeSymbolPrefixes.keys()) 124 if (sym->getName().startswith(prefix)) 125 return false; 126 for (StringRef suffix : excludeSymbolSuffixes.keys()) 127 if (sym->getName().endswith(suffix)) 128 return false; 129 130 // If a corresponding __imp_ symbol exists and is defined, don't export it. 131 if (symtab->find(("__imp_" + sym->getName()).str())) 132 return false; 133 134 // Check that file is non-null before dereferencing it, symbols not 135 // originating in regular object files probably shouldn't be exported. 136 if (!sym->getFile()) 137 return false; 138 139 StringRef libName = sys::path::filename(sym->getFile()->parentName); 140 141 // Drop the file extension. 142 libName = libName.substr(0, libName.rfind('.')); 143 if (!libName.empty()) 144 return !excludeLibs.count(libName); 145 146 StringRef fileName = sys::path::filename(sym->getFile()->getName()); 147 return !excludeObjects.count(fileName); 148 } 149 150 void writeDefFile(StringRef name) { 151 std::error_code ec; 152 raw_fd_ostream os(name, ec, sys::fs::OF_None); 153 if (ec) 154 fatal("cannot open " + name + ": " + ec.message()); 155 156 os << "EXPORTS\n"; 157 for (Export &e : config->exports) { 158 os << " " << e.exportName << " " 159 << "@" << e.ordinal; 160 if (auto *def = dyn_cast_or_null<Defined>(e.sym)) { 161 if (def && def->getChunk() && 162 !(def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE)) 163 os << " DATA"; 164 } 165 os << "\n"; 166 } 167 } 168 169 } // namespace coff 170 } // namespace lld 171