1 //===- LibDriver.cpp - lib.exe-compatible driver --------------------------===//
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 // Defines an interface to a lib.exe-compatible driver that also understands
10 // bitcode files. Used by llvm-lib and lld-link /lib.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ToolDrivers/llvm-lib/LibDriver.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringSet.h"
17 #include "llvm/BinaryFormat/COFF.h"
18 #include "llvm/BinaryFormat/Magic.h"
19 #include "llvm/Bitcode/BitcodeReader.h"
20 #include "llvm/Object/ArchiveWriter.h"
21 #include "llvm/Object/COFF.h"
22 #include "llvm/Object/WindowsMachineFlag.h"
23 #include "llvm/Option/Arg.h"
24 #include "llvm/Option/ArgList.h"
25 #include "llvm/Option/Option.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/Process.h"
29 #include "llvm/Support/StringSaver.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include <optional>
32 
33 using namespace llvm;
34 
35 namespace {
36 
37 enum {
38   OPT_INVALID = 0,
39 #define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_##ID,
40 #include "Options.inc"
41 #undef OPTION
42 };
43 
44 #define PREFIX(NAME, VALUE)                                                    \
45   static constexpr StringLiteral NAME##_init[] = VALUE;                        \
46   static constexpr ArrayRef<StringLiteral> NAME(NAME##_init,                   \
47                                                 std::size(NAME##_init) - 1);
48 #include "Options.inc"
49 #undef PREFIX
50 
51 static constexpr opt::OptTable::Info InfoTable[] = {
52 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
53   {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
54    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
55 #include "Options.inc"
56 #undef OPTION
57 };
58 
59 class LibOptTable : public opt::GenericOptTable {
60 public:
61   LibOptTable() : opt::GenericOptTable(InfoTable, true) {}
62 };
63 }
64 
65 static std::string getDefaultOutputPath(const NewArchiveMember &FirstMember) {
66   SmallString<128> Val = StringRef(FirstMember.Buf->getBufferIdentifier());
67   sys::path::replace_extension(Val, ".lib");
68   return std::string(Val.str());
69 }
70 
71 static std::vector<StringRef> getSearchPaths(opt::InputArgList *Args,
72                                              StringSaver &Saver) {
73   std::vector<StringRef> Ret;
74   // Add current directory as first item of the search path.
75   Ret.push_back("");
76 
77   // Add /libpath flags.
78   for (auto *Arg : Args->filtered(OPT_libpath))
79     Ret.push_back(Arg->getValue());
80 
81   // Add $LIB.
82   std::optional<std::string> EnvOpt = sys::Process::GetEnv("LIB");
83   if (!EnvOpt)
84     return Ret;
85   StringRef Env = Saver.save(*EnvOpt);
86   while (!Env.empty()) {
87     StringRef Path;
88     std::tie(Path, Env) = Env.split(';');
89     Ret.push_back(Path);
90   }
91   return Ret;
92 }
93 
94 static std::string findInputFile(StringRef File, ArrayRef<StringRef> Paths) {
95   for (StringRef Dir : Paths) {
96     SmallString<128> Path = Dir;
97     sys::path::append(Path, File);
98     if (sys::fs::exists(Path))
99       return std::string(Path);
100   }
101   return "";
102 }
103 
104 static void fatalOpenError(llvm::Error E, Twine File) {
105   if (!E)
106     return;
107   handleAllErrors(std::move(E), [&](const llvm::ErrorInfoBase &EIB) {
108     llvm::errs() << "error opening '" << File << "': " << EIB.message() << '\n';
109     exit(1);
110   });
111 }
112 
113 static void doList(opt::InputArgList& Args) {
114   // lib.exe prints the contents of the first archive file.
115   std::unique_ptr<MemoryBuffer> B;
116   for (auto *Arg : Args.filtered(OPT_INPUT)) {
117     // Create or open the archive object.
118     ErrorOr<std::unique_ptr<MemoryBuffer>> MaybeBuf = MemoryBuffer::getFile(
119         Arg->getValue(), /*IsText=*/false, /*RequiresNullTerminator=*/false);
120     fatalOpenError(errorCodeToError(MaybeBuf.getError()), Arg->getValue());
121 
122     if (identify_magic(MaybeBuf.get()->getBuffer()) == file_magic::archive) {
123       B = std::move(MaybeBuf.get());
124       break;
125     }
126   }
127 
128   // lib.exe doesn't print an error if no .lib files are passed.
129   if (!B)
130     return;
131 
132   Error Err = Error::success();
133   object::Archive Archive(B.get()->getMemBufferRef(), Err);
134   fatalOpenError(std::move(Err), B->getBufferIdentifier());
135 
136   for (auto &C : Archive.children(Err)) {
137     Expected<StringRef> NameOrErr = C.getName();
138     fatalOpenError(NameOrErr.takeError(), B->getBufferIdentifier());
139     StringRef Name = NameOrErr.get();
140     llvm::outs() << Name << '\n';
141   }
142   fatalOpenError(std::move(Err), B->getBufferIdentifier());
143 }
144 
145 static Expected<COFF::MachineTypes> getCOFFFileMachine(MemoryBufferRef MB) {
146   std::error_code EC;
147   auto Obj = object::COFFObjectFile::create(MB);
148   if (!Obj)
149     return Obj.takeError();
150 
151   uint16_t Machine = (*Obj)->getMachine();
152   if (Machine != COFF::IMAGE_FILE_MACHINE_I386 &&
153       Machine != COFF::IMAGE_FILE_MACHINE_AMD64 &&
154       Machine != COFF::IMAGE_FILE_MACHINE_ARMNT &&
155       Machine != COFF::IMAGE_FILE_MACHINE_ARM64) {
156     return createStringError(inconvertibleErrorCode(),
157                              "unknown machine: " + std::to_string(Machine));
158   }
159 
160   return static_cast<COFF::MachineTypes>(Machine);
161 }
162 
163 static Expected<COFF::MachineTypes> getBitcodeFileMachine(MemoryBufferRef MB) {
164   Expected<std::string> TripleStr = getBitcodeTargetTriple(MB);
165   if (!TripleStr)
166     return TripleStr.takeError();
167 
168   switch (Triple(*TripleStr).getArch()) {
169   case Triple::x86:
170     return COFF::IMAGE_FILE_MACHINE_I386;
171   case Triple::x86_64:
172     return COFF::IMAGE_FILE_MACHINE_AMD64;
173   case Triple::arm:
174     return COFF::IMAGE_FILE_MACHINE_ARMNT;
175   case Triple::aarch64:
176     return COFF::IMAGE_FILE_MACHINE_ARM64;
177   default:
178     return createStringError(inconvertibleErrorCode(),
179                              "unknown arch in target triple: " + *TripleStr);
180   }
181 }
182 
183 static void appendFile(std::vector<NewArchiveMember> &Members,
184                        COFF::MachineTypes &LibMachine,
185                        std::string &LibMachineSource, MemoryBufferRef MB) {
186   file_magic Magic = identify_magic(MB.getBuffer());
187 
188   if (Magic != file_magic::coff_object && Magic != file_magic::bitcode &&
189       Magic != file_magic::archive && Magic != file_magic::windows_resource &&
190       Magic != file_magic::coff_import_library) {
191     llvm::errs() << MB.getBufferIdentifier()
192                  << ": not a COFF object, bitcode, archive, import library or "
193                     "resource file\n";
194     exit(1);
195   }
196 
197   // If a user attempts to add an archive to another archive, llvm-lib doesn't
198   // handle the first archive file as a single file. Instead, it extracts all
199   // members from the archive and add them to the second archive. This behavior
200   // is for compatibility with Microsoft's lib command.
201   if (Magic == file_magic::archive) {
202     Error Err = Error::success();
203     object::Archive Archive(MB, Err);
204     fatalOpenError(std::move(Err), MB.getBufferIdentifier());
205 
206     for (auto &C : Archive.children(Err)) {
207       Expected<MemoryBufferRef> ChildMB = C.getMemoryBufferRef();
208       if (!ChildMB) {
209         handleAllErrors(ChildMB.takeError(), [&](const ErrorInfoBase &EIB) {
210           llvm::errs() << MB.getBufferIdentifier() << ": " << EIB.message()
211                        << "\n";
212         });
213         exit(1);
214       }
215 
216       appendFile(Members, LibMachine, LibMachineSource, *ChildMB);
217     }
218 
219     fatalOpenError(std::move(Err), MB.getBufferIdentifier());
220     return;
221   }
222 
223   // Check that all input files have the same machine type.
224   // Mixing normal objects and LTO bitcode files is fine as long as they
225   // have the same machine type.
226   // Doing this here duplicates the header parsing work that writeArchive()
227   // below does, but it's not a lot of work and it's a bit awkward to do
228   // in writeArchive() which needs to support many tools, can't assume the
229   // input is COFF, and doesn't have a good way to report errors.
230   if (Magic == file_magic::coff_object || Magic == file_magic::bitcode) {
231     Expected<COFF::MachineTypes> MaybeFileMachine =
232         (Magic == file_magic::coff_object) ? getCOFFFileMachine(MB)
233                                            : getBitcodeFileMachine(MB);
234     if (!MaybeFileMachine) {
235       handleAllErrors(MaybeFileMachine.takeError(),
236                       [&](const ErrorInfoBase &EIB) {
237                         llvm::errs() << MB.getBufferIdentifier() << ": "
238                                      << EIB.message() << "\n";
239                       });
240       exit(1);
241     }
242     COFF::MachineTypes FileMachine = *MaybeFileMachine;
243 
244     // FIXME: Once lld-link rejects multiple resource .obj files:
245     // Call convertResToCOFF() on .res files and add the resulting
246     // COFF file to the .lib output instead of adding the .res file, and remove
247     // this check. See PR42180.
248     if (FileMachine != COFF::IMAGE_FILE_MACHINE_UNKNOWN) {
249       if (LibMachine == COFF::IMAGE_FILE_MACHINE_UNKNOWN) {
250         LibMachine = FileMachine;
251         LibMachineSource =
252             (" (inferred from earlier file '" + MB.getBufferIdentifier() + "')")
253                 .str();
254       } else if (LibMachine != FileMachine) {
255         llvm::errs() << MB.getBufferIdentifier() << ": file machine type "
256                      << machineToStr(FileMachine)
257                      << " conflicts with library machine type "
258                      << machineToStr(LibMachine) << LibMachineSource << '\n';
259         exit(1);
260       }
261     }
262   }
263 
264   Members.emplace_back(MB);
265 }
266 
267 int llvm::libDriverMain(ArrayRef<const char *> ArgsArr) {
268   BumpPtrAllocator Alloc;
269   StringSaver Saver(Alloc);
270 
271   // Parse command line arguments.
272   SmallVector<const char *, 20> NewArgs(ArgsArr.begin(), ArgsArr.end());
273   cl::ExpandResponseFiles(Saver, cl::TokenizeWindowsCommandLine, NewArgs);
274   ArgsArr = NewArgs;
275 
276   LibOptTable Table;
277   unsigned MissingIndex;
278   unsigned MissingCount;
279   opt::InputArgList Args =
280       Table.ParseArgs(ArgsArr.slice(1), MissingIndex, MissingCount);
281   if (MissingCount) {
282     llvm::errs() << "missing arg value for \""
283                  << Args.getArgString(MissingIndex) << "\", expected "
284                  << MissingCount
285                  << (MissingCount == 1 ? " argument.\n" : " arguments.\n");
286     return 1;
287   }
288   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
289     llvm::errs() << "ignoring unknown argument: " << Arg->getAsString(Args)
290                  << "\n";
291 
292   // Handle /help
293   if (Args.hasArg(OPT_help)) {
294     Table.printHelp(outs(), "llvm-lib [options] file...", "LLVM Lib");
295     return 0;
296   }
297 
298   // Parse /ignore:
299   llvm::StringSet<> IgnoredWarnings;
300   for (auto *Arg : Args.filtered(OPT_ignore))
301     IgnoredWarnings.insert(Arg->getValue());
302 
303   // If no input files and not told otherwise, silently do nothing to match
304   // lib.exe
305   if (!Args.hasArgNoClaim(OPT_INPUT) && !Args.hasArg(OPT_llvmlibempty)) {
306     if (!IgnoredWarnings.contains("emptyoutput")) {
307       llvm::errs() << "warning: no input files, not writing output file\n";
308       llvm::errs() << "         pass /llvmlibempty to write empty .lib file,\n";
309       llvm::errs() << "         pass /ignore:emptyoutput to suppress warning\n";
310       if (Args.hasFlag(OPT_WX, OPT_WX_no, false)) {
311         llvm::errs() << "treating warning as error due to /WX\n";
312         return 1;
313       }
314     }
315     return 0;
316   }
317 
318   if (Args.hasArg(OPT_lst)) {
319     doList(Args);
320     return 0;
321   }
322 
323   std::vector<StringRef> SearchPaths = getSearchPaths(&Args, Saver);
324 
325   COFF::MachineTypes LibMachine = COFF::IMAGE_FILE_MACHINE_UNKNOWN;
326   std::string LibMachineSource;
327   if (auto *Arg = Args.getLastArg(OPT_machine)) {
328     LibMachine = getMachineType(Arg->getValue());
329     if (LibMachine == COFF::IMAGE_FILE_MACHINE_UNKNOWN) {
330       llvm::errs() << "unknown /machine: arg " << Arg->getValue() << '\n';
331       return 1;
332     }
333     LibMachineSource =
334         std::string(" (from '/machine:") + Arg->getValue() + "' flag)";
335   }
336 
337   std::vector<std::unique_ptr<MemoryBuffer>> MBs;
338   StringSet<> Seen;
339   std::vector<NewArchiveMember> Members;
340 
341   // Create a NewArchiveMember for each input file.
342   for (auto *Arg : Args.filtered(OPT_INPUT)) {
343     // Find a file
344     std::string Path = findInputFile(Arg->getValue(), SearchPaths);
345     if (Path.empty()) {
346       llvm::errs() << Arg->getValue() << ": no such file or directory\n";
347       return 1;
348     }
349 
350     // Input files are uniquified by pathname. If you specify the exact same
351     // path more than once, all but the first one are ignored.
352     //
353     // Note that there's a loophole in the rule; you can prepend `.\` or
354     // something like that to a path to make it look different, and they are
355     // handled as if they were different files. This behavior is compatible with
356     // Microsoft lib.exe.
357     if (!Seen.insert(Path).second)
358       continue;
359 
360     // Open a file.
361     ErrorOr<std::unique_ptr<MemoryBuffer>> MOrErr = MemoryBuffer::getFile(
362         Path, /*IsText=*/false, /*RequiresNullTerminator=*/false);
363     fatalOpenError(errorCodeToError(MOrErr.getError()), Path);
364     MemoryBufferRef MBRef = (*MOrErr)->getMemBufferRef();
365 
366     // Append a file.
367     appendFile(Members, LibMachine, LibMachineSource, MBRef);
368 
369     // Take the ownership of the file buffer to keep the file open.
370     MBs.push_back(std::move(*MOrErr));
371   }
372 
373   // Create an archive file.
374   std::string OutputPath;
375   if (auto *Arg = Args.getLastArg(OPT_out)) {
376     OutputPath = Arg->getValue();
377   } else if (!Members.empty()) {
378     OutputPath = getDefaultOutputPath(Members[0]);
379   } else {
380     llvm::errs() << "no output path given, and cannot infer with no inputs\n";
381     return 1;
382   }
383   // llvm-lib uses relative paths for both regular and thin archives, unlike
384   // standard GNU ar, which only uses relative paths for thin archives and
385   // basenames for regular archives.
386   for (NewArchiveMember &Member : Members) {
387     if (sys::path::is_relative(Member.MemberName)) {
388       Expected<std::string> PathOrErr =
389           computeArchiveRelativePath(OutputPath, Member.MemberName);
390       if (PathOrErr)
391         Member.MemberName = Saver.save(*PathOrErr);
392     }
393   }
394 
395   if (Error E =
396           writeArchive(OutputPath, Members,
397                        /*WriteSymtab=*/true, object::Archive::K_GNU,
398                        /*Deterministic*/ true, Args.hasArg(OPT_llvmlibthin))) {
399     handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
400       llvm::errs() << OutputPath << ": " << EI.message() << "\n";
401     });
402     return 1;
403   }
404 
405   return 0;
406 }
407