1 //===- DriverUtils.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 "Config.h"
10 #include "Driver.h"
11 #include "InputFiles.h"
12 #include "ObjC.h"
13 #include "Target.h"
14 
15 #include "lld/Common/Args.h"
16 #include "lld/Common/ErrorHandler.h"
17 #include "lld/Common/Memory.h"
18 #include "lld/Common/Reproduce.h"
19 #include "llvm/ADT/CachedHashString.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/Bitcode/BitcodeReader.h"
22 #include "llvm/LTO/LTO.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/FileSystem.h"
28 #include "llvm/Support/Path.h"
29 #include "llvm/TextAPI/InterfaceFile.h"
30 #include "llvm/TextAPI/TextAPIReader.h"
31 
32 using namespace llvm;
33 using namespace llvm::MachO;
34 using namespace llvm::opt;
35 using namespace llvm::sys;
36 using namespace lld;
37 using namespace lld::macho;
38 
39 // Create prefix string literals used in Options.td
40 #define PREFIX(NAME, VALUE) const char *NAME[] = VALUE;
41 #include "Options.inc"
42 #undef PREFIX
43 
44 // Create table mapping all options defined in Options.td
45 static const OptTable::Info optInfo[] = {
46 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
47   {X1, X2, X10,         X11,         OPT_##ID, Option::KIND##Class,            \
48    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
49 #include "Options.inc"
50 #undef OPTION
51 };
52 
53 MachOOptTable::MachOOptTable() : OptTable(optInfo) {}
54 
55 // Set color diagnostics according to --color-diagnostics={auto,always,never}
56 // or --no-color-diagnostics flags.
57 static void handleColorDiagnostics(InputArgList &args) {
58   const Arg *arg =
59       args.getLastArg(OPT_color_diagnostics, OPT_color_diagnostics_eq,
60                       OPT_no_color_diagnostics);
61   if (!arg)
62     return;
63   if (arg->getOption().getID() == OPT_color_diagnostics) {
64     lld::errs().enable_colors(true);
65   } else if (arg->getOption().getID() == OPT_no_color_diagnostics) {
66     lld::errs().enable_colors(false);
67   } else {
68     StringRef s = arg->getValue();
69     if (s == "always")
70       lld::errs().enable_colors(true);
71     else if (s == "never")
72       lld::errs().enable_colors(false);
73     else if (s != "auto")
74       error("unknown option: --color-diagnostics=" + s);
75   }
76 }
77 
78 InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
79   // Make InputArgList from string vectors.
80   unsigned missingIndex;
81   unsigned missingCount;
82   SmallVector<const char *, 256> vec(argv.data(), argv.data() + argv.size());
83 
84   // Expand response files (arguments in the form of @<filename>)
85   // and then parse the argument again.
86   cl::ExpandResponseFiles(saver, cl::TokenizeGNUCommandLine, vec);
87   InputArgList args = ParseArgs(vec, missingIndex, missingCount);
88 
89   // Handle -fatal_warnings early since it converts missing argument warnings
90   // to errors.
91   errorHandler().fatalWarnings = args.hasArg(OPT_fatal_warnings);
92 
93   if (missingCount)
94     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
95 
96   handleColorDiagnostics(args);
97 
98   for (const Arg *arg : args.filtered(OPT_UNKNOWN)) {
99     std::string nearest;
100     if (findNearest(arg->getAsString(args), nearest) > 1)
101       error("unknown argument '" + arg->getAsString(args) + "'");
102     else
103       error("unknown argument '" + arg->getAsString(args) +
104             "', did you mean '" + nearest + "'");
105   }
106   return args;
107 }
108 
109 void MachOOptTable::printHelp(const char *argv0, bool showHidden) const {
110   PrintHelp(lld::outs(), (std::string(argv0) + " [options] file...").c_str(),
111             "LLVM Linker", showHidden);
112   lld::outs() << "\n";
113 }
114 
115 static std::string rewritePath(StringRef s) {
116   if (fs::exists(s))
117     return relativeToRoot(s);
118   return std::string(s);
119 }
120 
121 static std::string rewriteInputPath(StringRef s) {
122   // Don't bother rewriting "absolute" paths that are actually under the
123   // syslibroot; simply rewriting the syslibroot is sufficient.
124   if (rerootPath(s) == s && fs::exists(s))
125     return relativeToRoot(s);
126   return std::string(s);
127 }
128 
129 // Reconstructs command line arguments so that so that you can re-run
130 // the same command with the same inputs. This is for --reproduce.
131 std::string macho::createResponseFile(const InputArgList &args) {
132   SmallString<0> data;
133   raw_svector_ostream os(data);
134 
135   // Copy the command line to the output while rewriting paths.
136   for (const Arg *arg : args) {
137     switch (arg->getOption().getID()) {
138     case OPT_reproduce:
139       break;
140     case OPT_INPUT:
141       os << quote(rewriteInputPath(arg->getValue())) << "\n";
142       break;
143     case OPT_o:
144       os << "-o " << quote(path::filename(arg->getValue())) << "\n";
145       break;
146     case OPT_filelist:
147       if (Optional<MemoryBufferRef> buffer = readFile(arg->getValue()))
148         for (StringRef path : args::getLines(*buffer))
149           os << quote(rewriteInputPath(path)) << "\n";
150       break;
151     case OPT_force_load:
152     case OPT_weak_library:
153       os << arg->getSpelling() << " "
154          << quote(rewriteInputPath(arg->getValue())) << "\n";
155       break;
156     case OPT_F:
157     case OPT_L:
158     case OPT_bundle_loader:
159     case OPT_exported_symbols_list:
160     case OPT_order_file:
161     case OPT_rpath:
162     case OPT_syslibroot:
163     case OPT_unexported_symbols_list:
164       os << arg->getSpelling() << " " << quote(rewritePath(arg->getValue()))
165          << "\n";
166       break;
167     case OPT_sectcreate:
168       os << arg->getSpelling() << " " << quote(arg->getValue(0)) << " "
169          << quote(arg->getValue(1)) << " "
170          << quote(rewritePath(arg->getValue(2))) << "\n";
171       break;
172     default:
173       os << toString(*arg) << "\n";
174     }
175   }
176   return std::string(data.str());
177 }
178 
179 static void searchedDylib(const Twine &path, bool found) {
180   if (config->printDylibSearch)
181     message("searched " + path + (found ? ", found " : ", not found"));
182   if (!found)
183     depTracker->logFileNotFound(path);
184 }
185 
186 Optional<std::string> macho::resolveDylibPath(StringRef dylibPath) {
187   // TODO: if a tbd and dylib are both present, we should check to make sure
188   // they are consistent.
189   bool dylibExists = fs::exists(dylibPath);
190   searchedDylib(dylibPath, dylibExists);
191   if (dylibExists)
192     return std::string(dylibPath);
193 
194   SmallString<261> tbdPath = dylibPath;
195   path::replace_extension(tbdPath, ".tbd");
196   bool tbdExists = fs::exists(tbdPath);
197   searchedDylib(tbdPath, tbdExists);
198   if (tbdExists)
199     return std::string(tbdPath);
200   return {};
201 }
202 
203 // It's not uncommon to have multiple attempts to load a single dylib,
204 // especially if it's a commonly re-exported core library.
205 static DenseMap<CachedHashStringRef, DylibFile *> loadedDylibs;
206 
207 DylibFile *macho::loadDylib(MemoryBufferRef mbref, DylibFile *umbrella,
208                             bool isBundleLoader) {
209   CachedHashStringRef path(mbref.getBufferIdentifier());
210   DylibFile *&file = loadedDylibs[path];
211   if (file)
212     return file;
213 
214   DylibFile *newFile;
215   file_magic magic = identify_magic(mbref.getBuffer());
216   if (magic == file_magic::tapi_file) {
217     Expected<std::unique_ptr<InterfaceFile>> result = TextAPIReader::get(mbref);
218     if (!result) {
219       error("could not load TAPI file at " + mbref.getBufferIdentifier() +
220             ": " + toString(result.takeError()));
221       return nullptr;
222     }
223     file = make<DylibFile>(**result, umbrella, isBundleLoader);
224 
225     // parseReexports() can recursively call loadDylib(). That's fine since
226     // we wrote the DylibFile we just loaded to the loadDylib cache via the
227     // `file` reference. But the recursive load can grow loadDylibs, so the
228     // `file` reference might become invalid after parseReexports() -- so copy
229     // the pointer it refers to before continuing.
230     newFile = file;
231     if (newFile->exportingFile)
232       newFile->parseReexports(**result);
233   } else {
234     assert(magic == file_magic::macho_dynamically_linked_shared_lib ||
235            magic == file_magic::macho_dynamically_linked_shared_lib_stub ||
236            magic == file_magic::macho_executable ||
237            magic == file_magic::macho_bundle);
238     file = make<DylibFile>(mbref, umbrella, isBundleLoader);
239 
240     // parseLoadCommands() can also recursively call loadDylib(). See comment
241     // in previous block for why this means we must copy `file` here.
242     newFile = file;
243     if (newFile->exportingFile)
244       newFile->parseLoadCommands(mbref);
245   }
246   return newFile;
247 }
248 
249 Optional<StringRef>
250 macho::findPathCombination(const Twine &name,
251                            const std::vector<StringRef> &roots,
252                            ArrayRef<StringRef> extensions) {
253   SmallString<261> base;
254   for (StringRef dir : roots) {
255     base = dir;
256     path::append(base, name);
257     for (StringRef ext : extensions) {
258       Twine location = base + ext;
259       bool exists = fs::exists(location);
260       searchedDylib(location, exists);
261       if (exists)
262         return saver.save(location.str());
263     }
264   }
265   return {};
266 }
267 
268 StringRef macho::rerootPath(StringRef path) {
269   if (!path::is_absolute(path, path::Style::posix) || path.endswith(".o"))
270     return path;
271 
272   if (Optional<StringRef> rerootedPath =
273           findPathCombination(path, config->systemLibraryRoots))
274     return *rerootedPath;
275 
276   return path;
277 }
278 
279 Optional<InputFile *> macho::loadArchiveMember(MemoryBufferRef mb,
280                                                uint32_t modTime,
281                                                StringRef archiveName,
282                                                bool objCOnly) {
283   if (config->zeroModTime)
284     modTime = 0;
285 
286   switch (identify_magic(mb.getBuffer())) {
287   case file_magic::macho_object:
288     if (!objCOnly || hasObjCSection(mb))
289       return make<ObjFile>(mb, modTime, archiveName);
290     return None;
291   case file_magic::bitcode:
292     if (!objCOnly || check(isBitcodeContainingObjCCategory(mb)))
293       return make<BitcodeFile>(mb);
294     return None;
295   default:
296     error(archiveName + ": archive member " + mb.getBufferIdentifier() +
297           " has unhandled file type");
298     return None;
299   }
300 }
301 
302 uint32_t macho::getModTime(StringRef path) {
303   if (config->zeroModTime)
304     return 0;
305 
306   fs::file_status stat;
307   if (!fs::status(path, stat))
308     if (fs::exists(stat))
309       return toTimeT(stat.getLastModificationTime());
310 
311   warn("failed to get modification time of " + path);
312   return 0;
313 }
314 
315 void macho::printArchiveMemberLoad(StringRef reason, const InputFile *f) {
316   if (config->printEachFile)
317     message(toString(f));
318   if (config->printWhyLoad)
319     message(reason + " forced load of " + toString(f));
320 }
321 
322 macho::DependencyTracker::DependencyTracker(StringRef path)
323     : path(path), active(!path.empty()) {
324   if (active && fs::exists(path) && !fs::can_write(path)) {
325     warn("Ignoring dependency_info option since specified path is not "
326          "writeable.");
327     active = false;
328   }
329 }
330 
331 void macho::DependencyTracker::write(llvm::StringRef version,
332                                      const llvm::SetVector<InputFile *> &inputs,
333                                      llvm::StringRef output) {
334   if (!active)
335     return;
336 
337   std::error_code ec;
338   llvm::raw_fd_ostream os(path, ec, llvm::sys::fs::OF_None);
339   if (ec) {
340     warn("Error writing dependency info to file");
341     return;
342   }
343 
344   auto addDep = [&os](DepOpCode opcode, const StringRef &path) {
345     // XXX: Even though DepOpCode's underlying type is uint8_t,
346     // this cast is still needed because Clang older than 10.x has a bug,
347     // where it doesn't know to cast the enum to its underlying type.
348     // Hence `<< DepOpCode` is ambiguous to it.
349     os << static_cast<uint8_t>(opcode);
350     os << path;
351     os << '\0';
352   };
353 
354   addDep(DepOpCode::Version, version);
355 
356   // Sort the input by its names.
357   std::vector<StringRef> inputNames;
358   inputNames.reserve(inputs.size());
359   for (InputFile *f : inputs)
360     inputNames.push_back(f->getName());
361   llvm::sort(inputNames);
362 
363   for (const StringRef &in : inputNames)
364     addDep(DepOpCode::Input, in);
365 
366   for (const std::string &f : notFounds)
367     addDep(DepOpCode::NotFound, f);
368 
369   addDep(DepOpCode::Output, output);
370 }
371