xref: /llvm-project-15.0.7/lld/MachO/Driver.cpp (revision d3dfd8ce) 
1 //===- Driver.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 "Driver.h"
10 #include "Config.h"
11 #include "InputFiles.h"
12 #include "OutputSection.h"
13 #include "OutputSegment.h"
14 #include "SymbolTable.h"
15 #include "Symbols.h"
16 #include "SyntheticSections.h"
17 #include "Target.h"
18 #include "Writer.h"
19 
20 #include "lld/Common/Args.h"
21 #include "lld/Common/Driver.h"
22 #include "lld/Common/ErrorHandler.h"
23 #include "lld/Common/LLVM.h"
24 #include "lld/Common/Memory.h"
25 #include "lld/Common/Version.h"
26 #include "llvm/ADT/DenseSet.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/StringRef.h"
29 #include "llvm/BinaryFormat/MachO.h"
30 #include "llvm/BinaryFormat/Magic.h"
31 #include "llvm/Object/Archive.h"
32 #include "llvm/Option/ArgList.h"
33 #include "llvm/Option/Option.h"
34 #include "llvm/Support/FileSystem.h"
35 #include "llvm/Support/Host.h"
36 #include "llvm/Support/MemoryBuffer.h"
37 #include "llvm/Support/Path.h"
38 
39 using namespace llvm;
40 using namespace llvm::MachO;
41 using namespace llvm::sys;
42 using namespace llvm::opt;
43 using namespace lld;
44 using namespace lld::macho;
45 
46 Configuration *lld::macho::config;
47 
48 // Create prefix string literals used in Options.td
49 #define PREFIX(NAME, VALUE) const char *NAME[] = VALUE;
50 #include "Options.inc"
51 #undef PREFIX
52 
53 // Create table mapping all options defined in Options.td
54 static const opt::OptTable::Info optInfo[] = {
55 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
56   {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
57    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
58 #include "Options.inc"
59 #undef OPTION
60 };
61 
62 MachOOptTable::MachOOptTable() : OptTable(optInfo) {}
63 
64 opt::InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
65   // Make InputArgList from string vectors.
66   unsigned missingIndex;
67   unsigned missingCount;
68   SmallVector<const char *, 256> vec(argv.data(), argv.data() + argv.size());
69 
70   opt::InputArgList args = ParseArgs(vec, missingIndex, missingCount);
71 
72   if (missingCount)
73     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
74 
75   for (opt::Arg *arg : args.filtered(OPT_UNKNOWN))
76     error("unknown argument: " + arg->getSpelling());
77   return args;
78 }
79 
80 void MachOOptTable::printHelp(const char *argv0, bool showHidden) const {
81   PrintHelp(lld::outs(), (std::string(argv0) + " [options] file...").c_str(),
82             "LLVM Linker", showHidden);
83   lld::outs() << "\n";
84 }
85 
86 static Optional<std::string> findWithExtension(StringRef base,
87                                                ArrayRef<StringRef> extensions) {
88   for (StringRef ext : extensions) {
89     Twine location = base + ext;
90     if (fs::exists(location))
91       return location.str();
92   }
93   return {};
94 }
95 
96 static Optional<std::string> findLibrary(StringRef name) {
97   llvm::SmallString<261> location;
98   for (StringRef dir : config->librarySearchPaths) {
99       location = dir;
100       path::append(location, Twine("lib") + name);
101       if (Optional<std::string> path =
102               findWithExtension(location, {".tbd", ".dylib", ".a"}))
103         return path;
104   }
105   return {};
106 }
107 
108 static Optional<std::string> findFramework(StringRef name) {
109   llvm::SmallString<260> symlink;
110   StringRef suffix;
111   std::tie(name, suffix) = name.split(",");
112   for (StringRef dir : config->frameworkSearchPaths) {
113     symlink = dir;
114     path::append(symlink, name + ".framework", name);
115 
116     if (!suffix.empty()) {
117       // NOTE: we must resolve the symlink before trying the suffixes, because
118       // there are no symlinks for the suffixed paths.
119       llvm::SmallString<260> location;
120       if (!fs::real_path(symlink, location)) {
121         // only append suffix if realpath() succeeds
122         Twine suffixed = location + suffix;
123         if (fs::exists(suffixed))
124           return suffixed.str();
125       }
126       // Suffix lookup failed, fall through to the no-suffix case.
127     }
128 
129     if (Optional<std::string> path = findWithExtension(symlink, {".tbd", ""}))
130       return path;
131   }
132   return {};
133 }
134 
135 static TargetInfo *createTargetInfo(opt::InputArgList &args) {
136   StringRef arch = args.getLastArgValue(OPT_arch, "x86_64");
137   config->arch = llvm::MachO::getArchitectureFromName(
138       args.getLastArgValue(OPT_arch, arch));
139   switch (config->arch) {
140   case llvm::MachO::AK_x86_64:
141   case llvm::MachO::AK_x86_64h:
142     return createX86_64TargetInfo();
143   default:
144     fatal("missing or unsupported -arch " + arch);
145   }
146 }
147 
148 static bool isDirectory(StringRef option, StringRef path) {
149   if (!fs::exists(path)) {
150     warn("directory not found for option -" + option + path);
151     return false;
152   } else if (!fs::is_directory(path)) {
153     warn("option -" + option + path + " references a non-directory path");
154     return false;
155   }
156   return true;
157 }
158 
159 static void getSearchPaths(std::vector<StringRef> &paths, unsigned optionCode,
160                            opt::InputArgList &args,
161                            const std::vector<StringRef> &roots,
162                            const SmallVector<StringRef, 2> &systemPaths) {
163   StringRef optionLetter{(optionCode == OPT_F ? "F" : "L")};
164   for (auto const &path : args::getStrings(args, optionCode)) {
165     // NOTE: only absolute paths are re-rooted to syslibroot(s)
166     if (llvm::sys::path::is_absolute(path, llvm::sys::path::Style::posix)) {
167       for (StringRef root : roots) {
168         SmallString<261> buffer(root);
169         llvm::sys::path::append(buffer, path);
170         // Do not warn about paths that are computed via the syslib roots
171         if (llvm::sys::fs::is_directory(buffer))
172           paths.push_back(saver.save(buffer.str()));
173       }
174     } else {
175       if (isDirectory(optionLetter, path))
176         paths.push_back(path);
177     }
178   }
179 
180   // `-Z` suppresses the standard "system" search paths.
181   if (args.hasArg(OPT_Z))
182     return;
183 
184   for (auto const &path : systemPaths) {
185     for (auto root : roots) {
186       SmallString<261> buffer(root);
187       llvm::sys::path::append(buffer, path);
188       if (isDirectory(optionLetter, buffer))
189         paths.push_back(saver.save(buffer.str()));
190     }
191   }
192 }
193 
194 static void getLibrarySearchPaths(opt::InputArgList &args,
195                                   const std::vector<StringRef> &roots,
196                                   std::vector<StringRef> &paths) {
197   getSearchPaths(paths, OPT_L, args, roots, {"/usr/lib", "/usr/local/lib"});
198 }
199 
200 static void getFrameworkSearchPaths(opt::InputArgList &args,
201                                     const std::vector<StringRef> &roots,
202                                     std::vector<StringRef> &paths) {
203   getSearchPaths(paths, OPT_F, args, roots,
204                  {"/Library/Frameworks", "/System/Library/Frameworks"});
205 }
206 
207 static void addFile(StringRef path) {
208   Optional<MemoryBufferRef> buffer = readFile(path);
209   if (!buffer)
210     return;
211   MemoryBufferRef mbref = *buffer;
212 
213   switch (identify_magic(mbref.getBuffer())) {
214   case file_magic::archive: {
215     std::unique_ptr<object::Archive> file = CHECK(
216         object::Archive::create(mbref), path + ": failed to parse archive");
217 
218     if (!file->isEmpty() && !file->hasSymbolTable())
219       error(path + ": archive has no index; run ranlib to add one");
220 
221     inputFiles.push_back(make<ArchiveFile>(std::move(file)));
222     break;
223   }
224   case file_magic::macho_object:
225     inputFiles.push_back(make<ObjFile>(mbref));
226     break;
227   case file_magic::macho_dynamically_linked_shared_lib:
228     inputFiles.push_back(make<DylibFile>(mbref));
229     break;
230   case file_magic::tapi_file: {
231     llvm::Expected<std::unique_ptr<llvm::MachO::InterfaceFile>> result =
232         TextAPIReader::get(mbref);
233     if (!result)
234       return;
235 
236     inputFiles.push_back(make<DylibFile>(std::move(*result)));
237     break;
238   }
239   default:
240     error(path + ": unhandled file type");
241   }
242 }
243 
244 static void addFileList(StringRef path) {
245   Optional<MemoryBufferRef> buffer = readFile(path);
246   if (!buffer)
247     return;
248   MemoryBufferRef mbref = *buffer;
249   for (StringRef path : args::getLines(mbref))
250     addFile(path);
251 }
252 
253 static std::array<StringRef, 6> archNames{"arm",    "arm64", "i386",
254                                           "x86_64", "ppc",   "ppc64"};
255 static bool isArchString(StringRef s) {
256   static DenseSet<StringRef> archNamesSet(archNames.begin(), archNames.end());
257   return archNamesSet.find(s) != archNamesSet.end();
258 }
259 
260 // An order file has one entry per line, in the following format:
261 //
262 //   <arch>:<object file>:<symbol name>
263 //
264 // <arch> and <object file> are optional. If not specified, then that entry
265 // matches any symbol of that name.
266 //
267 // If a symbol is matched by multiple entries, then it takes the lowest-ordered
268 // entry (the one nearest to the front of the list.)
269 //
270 // The file can also have line comments that start with '#'.
271 static void parseOrderFile(StringRef path) {
272   Optional<MemoryBufferRef> buffer = readFile(path);
273   if (!buffer) {
274     error("Could not read order file at " + path);
275     return;
276   }
277 
278   MemoryBufferRef mbref = *buffer;
279   size_t priority = std::numeric_limits<size_t>::max();
280   for (StringRef rest : args::getLines(mbref)) {
281     StringRef arch, objectFile, symbol;
282 
283     std::array<StringRef, 3> fields;
284     uint8_t fieldCount = 0;
285     while (rest != "" && fieldCount < 3) {
286       std::pair<StringRef, StringRef> p = getToken(rest, ": \t\n\v\f\r");
287       StringRef tok = p.first;
288       rest = p.second;
289 
290       // Check if we have a comment
291       if (tok == "" || tok[0] == '#')
292         break;
293 
294       fields[fieldCount++] = tok;
295     }
296 
297     switch (fieldCount) {
298     case 3:
299       arch = fields[0];
300       objectFile = fields[1];
301       symbol = fields[2];
302       break;
303     case 2:
304       (isArchString(fields[0]) ? arch : objectFile) = fields[0];
305       symbol = fields[1];
306       break;
307     case 1:
308       symbol = fields[0];
309       break;
310     case 0:
311       break;
312     default:
313       llvm_unreachable("too many fields in order file");
314     }
315 
316     if (!arch.empty()) {
317       if (!isArchString(arch)) {
318         error("invalid arch \"" + arch + "\" in order file: expected one of " +
319               llvm::join(archNames, ", "));
320         continue;
321       }
322 
323       // TODO: Update when we extend support for other archs
324       if (arch != "x86_64")
325         continue;
326     }
327 
328     if (!objectFile.empty() && !objectFile.endswith(".o")) {
329       error("invalid object file name \"" + objectFile +
330             "\" in order file: should end with .o");
331       continue;
332     }
333 
334     if (!symbol.empty()) {
335       SymbolPriorityEntry &entry = config->priorities[symbol];
336       if (!objectFile.empty())
337         entry.objectFiles.insert(std::make_pair(objectFile, priority));
338       else
339         entry.anyObjectFile = std::max(entry.anyObjectFile, priority);
340     }
341 
342     --priority;
343   }
344 }
345 
346 // We expect sub-library names of the form "libfoo", which will match a dylib
347 // with a path of .*/libfoo.dylib.
348 static bool markSubLibrary(StringRef searchName) {
349   for (InputFile *file : inputFiles) {
350     if (auto *dylibFile = dyn_cast<DylibFile>(file)) {
351       StringRef filename = path::filename(dylibFile->getName());
352       if (filename.consume_front(searchName) && filename == ".dylib") {
353         dylibFile->reexport = true;
354         return true;
355       }
356     }
357   }
358   return false;
359 }
360 
361 static void handlePlatformVersion(const opt::Arg *arg) {
362   // TODO: implementation coming very soon ...
363 }
364 
365 static void warnIfDeprecatedOption(const opt::Option &opt) {
366   if (!opt.getGroup().isValid())
367     return;
368   if (opt.getGroup().getID() == OPT_grp_deprecated) {
369     warn("Option `" + opt.getPrefixedName() + "' is deprecated in ld64:");
370     warn(opt.getHelpText());
371   }
372 }
373 
374 static void warnIfUnimplementedOption(const opt::Option &opt) {
375   if (!opt.getGroup().isValid())
376     return;
377   switch (opt.getGroup().getID()) {
378   case OPT_grp_deprecated:
379     // warn about deprecated options elsewhere
380     break;
381   case OPT_grp_undocumented:
382     warn("Option `" + opt.getPrefixedName() +
383          "' is undocumented. Should lld implement it?");
384     break;
385   case OPT_grp_obsolete:
386     warn("Option `" + opt.getPrefixedName() +
387          "' is obsolete. Please modernize your usage.");
388     break;
389   case OPT_grp_ignored:
390     warn("Option `" + opt.getPrefixedName() + "' is ignored.");
391     break;
392   default:
393     warn("Option `" + opt.getPrefixedName() +
394          "' is not yet implemented. Stay tuned...");
395     break;
396   }
397 }
398 
399 bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
400                  raw_ostream &stdoutOS, raw_ostream &stderrOS) {
401   lld::stdoutOS = &stdoutOS;
402   lld::stderrOS = &stderrOS;
403 
404   stderrOS.enable_colors(stderrOS.has_colors());
405   // TODO: Set up error handler properly, e.g. the errorLimitExceededMsg
406 
407   MachOOptTable parser;
408   opt::InputArgList args = parser.parse(argsArr.slice(1));
409 
410   if (args.hasArg(OPT_help_hidden)) {
411     parser.printHelp(argsArr[0], /*showHidden=*/true);
412     return true;
413   } else if (args.hasArg(OPT_help)) {
414     parser.printHelp(argsArr[0], /*showHidden=*/false);
415     return true;
416   }
417 
418   config = make<Configuration>();
419   symtab = make<SymbolTable>();
420   target = createTargetInfo(args);
421 
422   config->entry = symtab->addUndefined(args.getLastArgValue(OPT_e, "_main"));
423   config->outputFile = args.getLastArgValue(OPT_o, "a.out");
424   config->installName =
425       args.getLastArgValue(OPT_install_name, config->outputFile);
426   config->headerPad = args::getHex(args, OPT_headerpad, /*Default=*/32);
427   config->outputType = args.hasArg(OPT_dylib) ? MH_DYLIB : MH_EXECUTE;
428 
429   std::vector<StringRef> roots;
430   for (const Arg *arg : args.filtered(OPT_syslibroot))
431     roots.push_back(arg->getValue());
432   // NOTE: the final `-syslibroot` being `/` will ignore all roots
433   if (roots.size() && roots.back() == "/")
434     roots.clear();
435   // NOTE: roots can never be empty - add an empty root to simplify the library
436   // and framework search path computation.
437   if (roots.empty())
438     roots.emplace_back("");
439 
440   getLibrarySearchPaths(args, roots, config->librarySearchPaths);
441   getFrameworkSearchPaths(args, roots, config->frameworkSearchPaths);
442 
443   if (args.hasArg(OPT_v)) {
444     message(getLLDVersion());
445     message(StringRef("Library search paths:") +
446             (config->librarySearchPaths.size()
447                  ? "\n\t" + llvm::join(config->librarySearchPaths, "\n\t")
448                  : ""));
449     message(StringRef("Framework search paths:") +
450             (config->frameworkSearchPaths.size()
451                  ? "\n\t" + llvm::join(config->frameworkSearchPaths, "\n\t")
452                  : ""));
453     freeArena();
454     return !errorCount();
455   }
456 
457   for (const auto &arg : args) {
458     const auto &opt = arg->getOption();
459     warnIfDeprecatedOption(opt);
460     switch (arg->getOption().getID()) {
461     case OPT_INPUT:
462       addFile(arg->getValue());
463       break;
464     case OPT_filelist:
465       addFileList(arg->getValue());
466       break;
467     case OPT_l: {
468       StringRef name = arg->getValue();
469       if (Optional<std::string> path = findLibrary(name)) {
470         addFile(*path);
471         break;
472       }
473       error("library not found for -l" + name);
474       break;
475     }
476     case OPT_framework: {
477       StringRef name = arg->getValue();
478       if (Optional<std::string> path = findFramework(name)) {
479         addFile(*path);
480         break;
481       }
482       error("framework not found for -framework " + name);
483       break;
484     }
485     case OPT_platform_version:
486       handlePlatformVersion(arg);
487       break;
488     case OPT_o:
489     case OPT_dylib:
490     case OPT_e:
491     case OPT_F:
492     case OPT_L:
493     case OPT_headerpad:
494     case OPT_install_name:
495     case OPT_Z:
496     case OPT_arch:
497     case OPT_syslibroot:
498       // handled elsewhere
499       break;
500     default:
501       warnIfUnimplementedOption(opt);
502       break;
503     }
504   }
505 
506   // Now that all dylibs have been loaded, search for those that should be
507   // re-exported.
508   for (opt::Arg *arg : args.filtered(OPT_sub_library)) {
509     config->hasReexports = true;
510     StringRef searchName = arg->getValue();
511     if (!markSubLibrary(searchName))
512       error("-sub_library " + searchName + " does not match a supplied dylib");
513   }
514 
515   StringRef orderFile = args.getLastArgValue(OPT_order_file);
516   if (!orderFile.empty())
517     parseOrderFile(orderFile);
518 
519   if (config->outputType == MH_EXECUTE && !isa<Defined>(config->entry)) {
520     error("undefined symbol: " + config->entry->getName());
521     return false;
522   }
523 
524   createSyntheticSections();
525   symtab->addDSOHandle(in.header);
526 
527   // Initialize InputSections.
528   for (InputFile *file : inputFiles) {
529     for (SubsectionMap &map : file->subsections) {
530       for (auto &p : map) {
531         InputSection *isec = p.second;
532         inputSections.push_back(isec);
533       }
534     }
535   }
536 
537   // Write to an output file.
538   writeResult();
539 
540   if (canExitEarly)
541     exitLld(errorCount() ? 1 : 0);
542 
543   freeArena();
544   return !errorCount();
545 }
546