src/ld/parsers/generic_dylib_file.hpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2015 Apple Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
   6  *
   7  * This file contains Original Code and/or Modifications of Original Code
   8  * as defined in and that are subject to the Apple Public Source License
   9  * Version 2.0 (the 'License'). You may not use this file except in
  10  * compliance with the License. Please obtain a copy of the License at
  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  19  * Please see the License for the specific language governing rights and
  20  * limitations under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24
  25 #ifndef __GENERIC_DYLIB_FILE_H__
  26 #define __GENERIC_DYLIB_FILE_H__
  27
  28 #include "ld.hpp"
  29 #include "Options.h"
  30 #include <unordered_map>
  31 #include <unordered_set>
  32
  33 namespace generic {
  34 namespace dylib {
  35
  36 // forward reference
  37 template <typename A> class File;
  38
  39 //
  40 // An ExportAtom has no content.  It exists so that the linker can track which
  41 // imported symbols came from which dynamic libraries.
  42 //
  43 template <typename A>
  44 class ExportAtom final : public ld::Atom
  45 {
  46 public:
  47         ExportAtom(const File<A>& f, const char* nm, bool weakDef, bool tlv,
  48                            typename A::P::uint_t address)
  49                 : ld::Atom(f._importProxySection, ld::Atom::definitionProxy,
  50                                    (weakDef ? ld::Atom::combineByName : ld::Atom::combineNever),
  51                                    ld::Atom::scopeLinkageUnit,
  52                                    (tlv ? ld::Atom::typeTLV : ld::Atom::typeUnclassified),
  53                                    symbolTableNotIn, false, false, false, ld::Atom::Alignment(0)),
  54                   _file(f),
  55                   _name(nm),
  56                   _address(address)
  57         {}
  58
  59         // overrides of ld::Atom
  60         virtual const ld::File* file() const override final { return &_file; }
  61         virtual const char*             name() const override final { return _name; }
  62         virtual uint64_t                size() const override final { return 0; }
  63         virtual uint64_t                objectAddress() const override final { return _address; }
  64         virtual void                    copyRawContent(uint8_t buffer[]) const override final { }
  65
  66         virtual void                    setScope(Scope) { }
  67
  68 private:
  69         using pint_t = typename A::P::uint_t;
  70
  71         virtual                                 ~ExportAtom() {}
  72
  73         const File<A>&                  _file;
  74         const char*                             _name;
  75         pint_t                                  _address;
  76 };
  77
  78
  79 //
  80 // An ImportAtom has no content.  It exists so that when linking a main executable flat-namespace
  81 // the imports of all flat dylibs are checked
  82 //
  83 template <typename A>
  84 class ImportAtom final : public ld::Atom
  85 {
  86 public:
  87         ImportAtom(File<A>& f, std::vector<const char*>& imports);
  88
  89         // overrides of ld::Atom
  90         virtual ld::File*                               file() const override final { return &_file; }
  91         virtual const char*                             name() const override final { return "import-atom"; }
  92         virtual uint64_t                                size() const override final { return 0; }
  93         virtual uint64_t                                objectAddress() const override final { return 0; }
  94         virtual ld::Fixup::iterator             fixupsBegin() const     override final { return &_undefs[0]; }
  95         virtual ld::Fixup::iterator             fixupsEnd()     const override final { return &_undefs[_undefs.size()]; }
  96         virtual void                                    copyRawContent(uint8_t buffer[]) const override final { }
  97
  98         virtual void                                    setScope(Scope)         { }
  99
 100 private:
 101         virtual                                                 ~ImportAtom() {}
 102
 103         File<A>&                                                _file;
 104         mutable std::vector<ld::Fixup>  _undefs;
 105 };
 106
 107 template <typename A>
 108 ImportAtom<A>::ImportAtom(File<A>& f, std::vector<const char*>& imports)
 109         : ld::Atom(f._flatDummySection, ld::Atom::definitionRegular, ld::Atom::combineNever,
 110                            ld::Atom::scopeTranslationUnit, ld::Atom::typeUnclassified, symbolTableNotIn, false,
 111                            false, false, ld::Atom::Alignment(0)),
 112           _file(f)
 113 {
 114         for(auto *name : imports)
 115                 _undefs.emplace_back(0, ld::Fixup::k1of1, ld::Fixup::kindNone, false, strdup(name));
 116 }
 117
 118 //
 119 // A generic representation for the dynamic library files we support (Mach-O and text-based stubs).
 120 // Common state and functionality is consolidated in this class.
 121 //
 122 template <typename A>
 123 class File : public ld::dylib::File
 124 {
 125 public:
 126         File(const char* path, time_t mTime, ld::File::Ordinal ordinal, Options::Platform platform,
 127                  uint32_t linkMinOSVersion, bool allowWeakImports, bool linkingFlatNamespace, bool hoistImplicitPublicDylibs,
 128                  bool allowSimToMacOSX, bool addVers);
 129
 130         // overrides of ld::File
 131         virtual bool                                                    forEachAtom(ld::File::AtomHandler&) const override final;
 132         virtual bool                                                    justInTimeforEachAtom(const char* name, ld::File::AtomHandler&) const override final;
 133         virtual ld::File::ObjcConstraint                objCConstraint() const override final { return _objcConstraint; }
 134         virtual uint8_t                                                 swiftVersion() const override final { return _swiftVersion; }
 135         virtual uint32_t                                                minOSVersion() const override final { return _minVersionInDylib; }
 136         virtual uint32_t                                                platformLoadCommand() const     override final { return _platformInDylib; }
 137         virtual ld::Bitcode*                                    getBitcode() const override final { return _bitcode.get(); }
 138
 139
 140         // overrides of ld::dylib::File
 141         virtual void                                                    processIndirectLibraries(ld::dylib::File::DylibHandler*, bool addImplicitDylibs) override final;
 142         virtual bool                                                    providedExportAtom() const      override final { return _providedAtom; }
 143         virtual const char*                                             parentUmbrella() const override final { return _parentUmbrella; }
 144         virtual const std::vector<const char*>* allowableClients() const override final { return _allowableClients.empty() ? nullptr : &_allowableClients; }
 145     virtual const std::vector<const char*>&     rpaths() const override final { return _rpaths; }
 146         virtual bool                                                    hasWeakExternals() const override final { return _hasWeakExports; }
 147         virtual bool                                                    deadStrippable() const override final { return _deadStrippable; }
 148         virtual bool                                                    hasWeakDefinition(const char* name) const override final;
 149         virtual bool                                                    hasPublicInstallName() const override final { return _hasPublicInstallName; }
 150         virtual bool                                                    allSymbolsAreWeakImported() const override final;
 151         virtual bool                                                    installPathVersionSpecific() const override final { return _installPathOverride; }
 152         virtual bool                                                    appExtensionSafe() const override final { return _appExtensionSafe; };
 153
 154
 155         bool                                                                    wrongOS() const { return _wrongOS; }
 156
 157 private:
 158         using pint_t = typename A::P::uint_t;
 159
 160         friend class ExportAtom<A>;
 161         friend class ImportAtom<A>;
 162
 163         struct CStringHash {
 164                 std::size_t operator()(const char* __s) const {
 165                         unsigned long __h = 0;
 166                         for ( ; *__s; ++__s)
 167                                 __h = 5 * __h + *__s;
 168                         return size_t(__h);
 169                 };
 170         };
 171
 172 protected:
 173         struct AtomAndWeak { ld::Atom* atom; bool weakDef; bool tlv; pint_t address; };
 174         struct Dependent {
 175         const char* path;
 176         File<A>* dylib;
 177         bool reExport;
 178
 179         Dependent(const char* path, bool reExport)
 180             : path(path), dylib(nullptr), reExport(reExport) {}
 181     };
 182         struct ReExportChain { ReExportChain* prev; const File* file; };
 183
 184 private:
 185         using NameToAtomMap = std::unordered_map<const char*, AtomAndWeak, ld::CStringHash, ld::CStringEquals>;
 186         using NameSet = std::unordered_set<const char*, CStringHash, ld::CStringEquals>;
 187
 188         std::pair<bool, bool>           hasWeakDefinitionImpl(const char* name) const;
 189         bool                                            containsOrReExports(const char* name, bool& weakDef, bool& tlv, pint_t& addr) const;
 190         void                                            assertNoReExportCycles(ReExportChain*) const;
 191
 192 protected:
 193         bool                                            isPublicLocation(const char* path) const;
 194
 195 private:
 196         ld::Section                                                     _importProxySection;
 197         ld::Section                                                     _flatDummySection;
 198         mutable bool                                            _providedAtom;
 199         bool                                                            _indirectDylibsProcessed;
 200
 201 protected:
 202         mutable NameToAtomMap                           _atoms;
 203         NameSet                                                         _ignoreExports;
 204         std::vector<Dependent>                          _dependentDylibs;
 205         ImportAtom<A>*                                          _importAtom;
 206         std::vector<const char*>                        _allowableClients;
 207         std::vector<const char*>                        _rpaths;
 208         const char*                                                     _parentUmbrella;
 209         std::unique_ptr<ld::Bitcode>            _bitcode;
 210         const Options::Platform                         _platform;
 211         ld::File::ObjcConstraint                        _objcConstraint;
 212         const uint32_t                                          _linkMinOSVersion;
 213         uint32_t                                                        _minVersionInDylib;
 214         uint32_t                                                        _platformInDylib;
 215         uint8_t                                                         _swiftVersion;
 216         bool                                                            _wrongOS;
 217         bool                                                            _linkingFlat;
 218         bool                                                            _noRexports;
 219         bool                                                            _explictReExportFound;
 220         bool                                                            _implicitlyLinkPublicDylibs;
 221         bool                                                            _installPathOverride;
 222         bool                                                            _hasWeakExports;
 223         bool                                                            _deadStrippable;
 224         bool                                                            _hasPublicInstallName;
 225         bool                                                            _appExtensionSafe;
 226     const bool                          _allowWeakImports;
 227         const bool                                                      _allowSimToMacOSXLinking;
 228         const bool                                                      _addVersionLoadCommand;
 229
 230         static bool                                                     _s_logHashtable;
 231 };
 232
 233 template <typename A>
 234 bool File<A>::_s_logHashtable = false;
 235
 236 template <typename A>
 237 File<A>::File(const char* path, time_t mTime, ld::File::Ordinal ord,  Options::Platform platform,
 238                           uint32_t linkMinOSVersion, bool allowWeakImports, bool linkingFlatNamespace,
 239                           bool hoistImplicitPublicDylibs,
 240                           bool allowSimToMacOSX, bool addVers)
 241         : ld::dylib::File(path, mTime, ord),
 242           _importProxySection("__TEXT", "__import", ld::Section::typeImportProxies, true),
 243           _flatDummySection("__LINKEDIT", "__flat_dummy", ld::Section::typeLinkEdit, true),
 244           _providedAtom(false),
 245           _indirectDylibsProcessed(false),
 246           _importAtom(nullptr),
 247           _parentUmbrella(nullptr),
 248           _platform(platform),
 249           _objcConstraint(ld::File::objcConstraintNone),
 250           _linkMinOSVersion(linkMinOSVersion),
 251           _minVersionInDylib(0),
 252           _platformInDylib(Options::kPlatformUnknown),
 253           _swiftVersion(0),
 254           _wrongOS(false),
 255           _linkingFlat(linkingFlatNamespace),
 256           _noRexports(false),
 257           _explictReExportFound(false),
 258           _implicitlyLinkPublicDylibs(hoistImplicitPublicDylibs),
 259           _installPathOverride(false),
 260           _hasWeakExports(false),
 261           _deadStrippable(false),
 262           _hasPublicInstallName(false),
 263           _appExtensionSafe(false),
 264       _allowWeakImports(allowWeakImports),
 265           _allowSimToMacOSXLinking(allowSimToMacOSX),
 266           _addVersionLoadCommand(addVers)
 267 {
 268 }
 269
 270 template <typename A>
 271 std::pair<bool, bool> File<A>::hasWeakDefinitionImpl(const char* name) const
 272 {
 273         const auto pos = _atoms.find(name);
 274         if ( pos != this->_atoms.end() )
 275                 return std::make_pair(true, pos->second.weakDef);
 276
 277         // look in re-exported libraries.
 278         for (const auto &dep : _dependentDylibs) {
 279                 if ( dep.reExport ) {
 280                         auto ret = dep.dylib->hasWeakDefinitionImpl(name);
 281                         if ( ret.first )
 282                                 return ret;
 283                 }
 284         }
 285         return std::make_pair(false, false);
 286 }
 287
 288 template <typename A>
 289 bool File<A>::hasWeakDefinition(const char* name) const
 290 {
 291         // If we are supposed to ignore this export, then pretend we don't have it.
 292         if ( _ignoreExports.count(name) != 0 )
 293                 return false;
 294
 295         return hasWeakDefinitionImpl(name).second;
 296 }
 297
 298 template <typename A>
 299 bool File<A>::containsOrReExports(const char* name, bool& weakDef, bool& tlv, pint_t& addr) const
 300 {
 301         if ( _ignoreExports.count(name) != 0 )
 302                 return false;
 303
 304         // check myself
 305         const auto pos = _atoms.find(name);
 306         if ( pos != _atoms.end() ) {
 307                 weakDef = pos->second.weakDef;
 308                 tlv = pos->second.tlv;
 309                 addr = pos->second.address;
 310                 return true;
 311         }
 312
 313         // check dylibs I re-export
 314         for (const auto& dep : _dependentDylibs) {
 315                 if ( dep.reExport && !dep.dylib->implicitlyLinked() ) {
 316                         if ( dep.dylib->containsOrReExports(name, weakDef, tlv, addr) )
 317                                 return true;
 318                 }
 319         }
 320
 321         return false;
 322 }
 323
 324 template <typename A>
 325 bool File<A>::forEachAtom(ld::File::AtomHandler& handler) const
 326 {
 327         handler.doFile(*this);
 328
 329         // if doing flatnamespace and need all this dylib's imports resolve
 330         // add atom which references alls undefines in this dylib
 331         if ( _importAtom != nullptr ) {
 332                 handler.doAtom(*_importAtom);
 333                 return true;
 334         }
 335         return false;
 336 }
 337
 338 template <typename A>
 339 bool File<A>::justInTimeforEachAtom(const char* name, ld::File::AtomHandler& handler) const
 340 {
 341         // If we are supposed to ignore this export, then pretend we don't have it.
 342         if ( _ignoreExports.count(name) != 0 )
 343                 return false;
 344
 345
 346         AtomAndWeak bucket;
 347         if ( containsOrReExports(name, bucket.weakDef, bucket.tlv, bucket.address) ) {
 348                 bucket.atom = new ExportAtom<A>(*this, name, bucket.weakDef, bucket.tlv, bucket.address);
 349                 _atoms[name] = bucket;
 350                 _providedAtom = true;
 351                 if ( _s_logHashtable )
 352                         fprintf(stderr, "getJustInTimeAtomsFor: %s found in %s\n", name, this->path());
 353                 // call handler with new export atom
 354                 handler.doAtom(*bucket.atom);
 355                 return true;
 356         }
 357
 358         return false;
 359 }
 360
 361 template <typename A>
 362 void File<A>::assertNoReExportCycles(ReExportChain* prev) const
 363 {
 364         // recursively check my re-exported dylibs
 365         ReExportChain chain = { prev, this };
 366         for (const auto &dep : _dependentDylibs) {
 367                 if ( dep.reExport ) {
 368                         auto* child = dep.dylib;
 369                         // check child is not already in chain
 370                         for (auto* p = prev; p != nullptr; p = p->prev) {
 371                                 if ( p->file == child ) {
 372                                         throwf("cycle in dylib re-exports with %s and %s", child->path(), this->path());
 373                                 }
 374                         }
 375                         if ( dep.dylib != nullptr )
 376                                 dep.dylib->assertNoReExportCycles(&chain);
 377                 }
 378         }
 379 }
 380
 381 template <typename A>
 382 void File<A>::processIndirectLibraries(ld::dylib::File::DylibHandler* handler, bool addImplicitDylibs)
 383 {
 384         // only do this once
 385         if ( _indirectDylibsProcessed )
 386                 return;
 387
 388         const static bool log = false;
 389         if ( log )
 390                 fprintf(stderr, "processIndirectLibraries(%s)\n", this->installPath());
 391         if ( _linkingFlat ) {
 392                 for (auto &dep : _dependentDylibs)
 393                         dep.dylib = (File<A>*)handler->findDylib(dep.path, this, false);
 394         }
 395         else if ( _noRexports ) {
 396                 // MH_NO_REEXPORTED_DYLIBS bit set, then nothing to do
 397         }
 398         else {
 399                 // two-level, might have re-exports
 400                 for (auto &dep : this->_dependentDylibs) {
 401                         if ( dep.reExport ) {
 402                                 if ( log )
 403                                         fprintf(stderr, "processIndirectLibraries() parent=%s, child=%s\n", this->installPath(), dep.path);
 404                                 // a LC_REEXPORT_DYLIB, LC_SUB_UMBRELLA or LC_SUB_LIBRARY says we re-export this child
 405                                 dep.dylib = (File<A>*)handler->findDylib(dep.path, this, this->speculativelyLoaded());
 406                                 if ( dep.dylib->hasPublicInstallName() && !dep.dylib->wrongOS() ) {
 407                                         // promote this child to be automatically added as a direct dependent if this already is
 408                                         if ( (this->explicitlyLinked() || this->implicitlyLinked()) && (strcmp(dep.path, dep.dylib->installPath()) == 0) ) {
 409                                                 if ( log )
 410                                                         fprintf(stderr, "processIndirectLibraries() implicitly linking %s\n", dep.dylib->installPath());
 411                                                 dep.dylib->setImplicitlyLinked();
 412                                         }
 413                                         else if ( dep.dylib->explicitlyLinked() || dep.dylib->implicitlyLinked() ) {
 414                                                 if ( log )
 415                                                         fprintf(stderr, "processIndirectLibraries() parent is not directly linked, but child is, so no need to re-export child\n");
 416                                         }
 417                                         else {
 418                                                 if ( log )
 419                                                         fprintf(stderr, "processIndirectLibraries() parent is not directly linked, so parent=%s will re-export child=%s\n", this->installPath(), dep.path);
 420                                         }
 421                                 }
 422                                 else {
 423                                         // add all child's symbols to me
 424                                         if ( log )
 425                                                 fprintf(stderr, "processIndirectLibraries() child is not public, so parent=%s will re-export child=%s\n", this->installPath(), dep.path);
 426                                 }
 427                         }
 428                         else if ( !_explictReExportFound ) {
 429                                 // see if child contains LC_SUB_FRAMEWORK with my name
 430                                 dep.dylib = (File<A>*)handler->findDylib(dep.path, this, this->speculativelyLoaded());
 431                                 const char* parentUmbrellaName = dep.dylib->parentUmbrella();
 432                                 if ( parentUmbrellaName != nullptr ) {
 433                                         const char* parentName = this->path();
 434                                         const char* lastSlash = strrchr(parentName, '/');
 435                                         if ( (lastSlash != nullptr) && (strcmp(&lastSlash[1], parentUmbrellaName) == 0) ) {
 436                                                 // add all child's symbols to me
 437                                                 dep.reExport = true;
 438                                                 if ( log )
 439                                                         fprintf(stderr, "processIndirectLibraries() umbrella=%s will re-export child=%s\n", this->installPath(), dep.path);
 440                                         }
 441                                 }
 442                         }
 443                 }
 444         }
 445
 446         // check for re-export cycles
 447         ReExportChain chain = { nullptr, this };
 448         this->assertNoReExportCycles(&chain);
 449
 450         _indirectDylibsProcessed = true;
 451 }
 452
 453 template <typename A>
 454 bool File<A>::isPublicLocation(const char* path) const
 455 {
 456         // -no_implicit_dylibs disables this optimization
 457         if ( ! _implicitlyLinkPublicDylibs )
 458                 return false;
 459
 460         // /usr/lib is a public location
 461         if ( (strncmp(path, "/usr/lib/", 9) == 0) && (strchr(&path[9], '/') == nullptr) )
 462                 return true;
 463
 464         // /System/Library/Frameworks/ is a public location
 465         if ( strncmp(path, "/System/Library/Frameworks/", 27) == 0 ) {
 466                 const char* frameworkDot = strchr(&path[27], '.');
 467                 // but only top level framework
 468                 // /System/Library/Frameworks/Foo.framework/Versions/A/Foo                 ==> true
 469                 // /System/Library/Frameworks/Foo.framework/Resources/libBar.dylib         ==> false
 470                 // /System/Library/Frameworks/Foo.framework/Frameworks/Bar.framework/Bar   ==> false
 471                 // /System/Library/Frameworks/Foo.framework/Frameworks/Xfoo.framework/XFoo ==> false
 472                 if ( frameworkDot != nullptr ) {
 473                         int frameworkNameLen = frameworkDot - &path[27];
 474                         if ( strncmp(&path[strlen(path)-frameworkNameLen-1], &path[26], frameworkNameLen+1) == 0 )
 475                                 return true;
 476                 }
 477         }
 478
 479         return false;
 480 }
 481
 482 // <rdar://problem/5529626> If only weak_import symbols are used, linker should use LD_LOAD_WEAK_DYLIB
 483 template <typename A>
 484 bool File<A>::allSymbolsAreWeakImported() const
 485 {
 486         bool foundNonWeakImport = false;
 487         bool foundWeakImport = false;
 488         //fprintf(stderr, "%s:\n", this->path());
 489         for (const auto &it : _atoms) {
 490                 auto* atom = it.second.atom;
 491                 if ( atom != nullptr ) {
 492                         if ( atom->weakImported() )
 493                                 foundWeakImport = true;
 494                         else
 495                                 foundNonWeakImport = true;
 496                         //fprintf(stderr, "  weak_import=%d, name=%s\n", atom->weakImported(), it->first);
 497                 }
 498         }
 499
 500         // don't automatically weak link dylib with no imports
 501         // so at least one weak import symbol and no non-weak-imported symbols must be found
 502         return foundWeakImport && !foundNonWeakImport;
 503 }
 504
 505
 506 } // end namespace dylib
 507 } // end namespace generic
 508
 509 #endif // __GENERIC_DYLIB_FILE_H__