src/ld/MachOReaderDylib.hpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2005-2007 Apple Inc. All rights reserved.
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  24
  25 #ifndef __OBJECT_FILE_DYLIB_MACH_O__
  26 #define __OBJECT_FILE_DYLIB_MACH_O__
  27
  28 #include <stdint.h>
  29 #include <math.h>
  30 #include <unistd.h>
  31 #include <sys/param.h>
  32
  33
  34 #include <vector>
  35 #include <set>
  36 #include <algorithm>
  37 #include <ext/hash_map>
  38
  39 #include "MachOFileAbstraction.hpp"
  40 #include "MachOTrie.hpp"
  41 #include "ObjectFile.h"
  42
  43 //
  44 //
  45 //      To implement architecture xxx, you must write template specializations for the following method:
  46 //                      Reader<xxx>::validFile()
  47 //
  48 //
  49
  50
  51
  52
  53 namespace mach_o {
  54 namespace dylib {
  55
  56
  57 // forward reference
  58 template <typename A> class Reader;
  59
  60
  61 class Segment : public ObjectFile::Segment
  62 {
  63 public:
  64                                                                 Segment(const char* name)               { fName = name; }
  65         virtual const char*                     getName() const                                 { return fName; }
  66         virtual bool                            isContentReadable() const               { return true; }
  67         virtual bool                            isContentWritable() const               { return false; }
  68         virtual bool                            isContentExecutable() const             { return false; }
  69 private:
  70         const char*                                     fName;
  71 };
  72
  73
  74 //
  75 // An ExportAtom has no content.  It exists so that the linker can track which imported
  76 // symbols came from which dynamic libraries.
  77 //
  78 template <typename A>
  79 class ExportAtom : public ObjectFile::Atom
  80 {
  81 public:
  82         virtual ObjectFile::Reader*                                     getFile() const                         { return &fOwner; }
  83         virtual bool                                                            getTranslationUnitSource(const char** dir, const char** name) const { return false; }
  84         virtual const char*                                                     getName() const                         { return fName; }
  85         virtual const char*                                                     getDisplayName() const          { return fName; }
  86         virtual Scope                                                           getScope() const                        { return ObjectFile::Atom::scopeGlobal; }
  87         virtual DefinitionKind                                          getDefinitionKind() const       { return fWeakDefinition ? kExternalWeakDefinition : kExternalDefinition; }
  88         virtual SymbolTableInclusion                            getSymbolTableInclusion() const { return ObjectFile::Atom::kSymbolTableIn; }
  89         virtual bool                                                            dontDeadStrip() const           { return false; }
  90         virtual bool                                                            isZeroFill() const                      { return false; }
  91         virtual bool                                                            isThumb() const                         { return false; }
  92         virtual uint64_t                                                        getSize() const                         { return 0; }
  93         virtual std::vector<ObjectFile::Reference*>&  getReferences() const             { return fgEmptyReferenceList; }
  94         virtual bool                                                            mustRemainInSection() const { return false; }
  95         virtual const char*                                                     getSectionName() const          { return "._imports"; }
  96         virtual Segment&                                                        getSegment() const                      { return fgImportSegment; }
  97         virtual ObjectFile::Atom&                                       getFollowOnAtom() const         { return *((ObjectFile::Atom*)NULL); }
  98         virtual uint32_t                                                        getOrdinal() const                      { return fOrdinal; }
  99         virtual std::vector<ObjectFile::LineInfo>*      getLineInfo() const                     { return NULL; }
 100         virtual ObjectFile::Alignment                           getAlignment() const            { return ObjectFile::Alignment(0); }
 101         virtual void                                                            copyRawContent(uint8_t buffer[]) const  {}
 102
 103         virtual void                                                            setScope(Scope)                         { }
 104
 105 protected:
 106         friend class Reader<A>;
 107         typedef typename A::P                                   P;
 108
 109                                                                                         ExportAtom(ObjectFile::Reader& owner, const char* name, bool weak, uint32_t ordinal)
 110                                                                                                 : fOwner(owner), fName(name), fOrdinal(ordinal), fWeakDefinition(weak) {}
 111         virtual                                                                 ~ExportAtom() {}
 112
 113         ObjectFile::Reader&                                             fOwner;
 114         const char*                                                             fName;
 115         uint32_t                                                                fOrdinal;
 116         bool                                                                    fWeakDefinition;
 117
 118         static std::vector<ObjectFile::Reference*>      fgEmptyReferenceList;
 119         static Segment                                                          fgImportSegment;
 120 };
 121
 122 template <typename A>
 123 Segment                                                         ExportAtom<A>::fgImportSegment("__LINKEDIT");
 124
 125 template <typename A>
 126 std::vector<ObjectFile::Reference*>     ExportAtom<A>::fgEmptyReferenceList;
 127
 128
 129
 130 class ImportReference : public ObjectFile::Reference
 131 {
 132 public:
 133                                                         ImportReference(const char* name)
 134                                                                 : fTarget(NULL), fTargetName(strdup(name))  {}
 135         virtual                                 ~ImportReference() {}
 136
 137
 138         virtual ObjectFile::Reference::TargetBinding    getTargetBinding() const        { return (fTarget==NULL) ? ObjectFile::Reference::kUnboundByName : ObjectFile::Reference::kBoundByName; }
 139         virtual ObjectFile::Reference::TargetBinding    getFromTargetBinding() const{ return ObjectFile::Reference::kDontBind; }
 140         virtual uint8_t                                                                 getKind() const                         { return 0; }
 141         virtual uint64_t                                                                getFixUpOffset() const          { return 0; }
 142         virtual const char*                                                             getTargetName() const           { return fTargetName; }
 143         virtual ObjectFile::Atom&                                               getTarget() const                       { return *((ObjectFile::Atom*)fTarget); }
 144         virtual uint64_t                                                                getTargetOffset() const         { return 0; }
 145         virtual ObjectFile::Atom&                                               getFromTarget() const           { return *((ObjectFile::Atom*)NULL); }
 146         virtual const char*                                                             getFromTargetName() const       { return NULL; }
 147         virtual uint64_t                                                                getFromTargetOffset() const { return 0; }
 148         virtual void                                                                    setTarget(ObjectFile::Atom& atom, uint64_t offset) { fTarget = &atom; }
 149         virtual void                                                                    setFromTarget(ObjectFile::Atom&) { throw "can't set from target"; }
 150         virtual const char*                                                             getDescription() const          { return "dylib import reference"; }
 151
 152 private:
 153         const ObjectFile::Atom* fTarget;
 154         const char*                             fTargetName;
 155 };
 156
 157
 158 //
 159 // An ImportAtom has no content.  It exists so that when linking a main executable flat-namespace
 160 // the imports of all flat dylibs are checked
 161 //
 162 template <typename A>
 163 class ImportAtom : public ObjectFile::Atom
 164 {
 165 public:
 166         virtual ObjectFile::Reader*                                     getFile() const                         { return &fOwner; }
 167         virtual bool                                                            getTranslationUnitSource(const char** dir, const char** name) const { return false; }
 168         virtual const char*                                                     getName() const                         { return "flat-imports"; }
 169         virtual const char*                                                     getDisplayName() const          { return "flat_namespace undefines"; }
 170         virtual Scope                                                           getScope() const                        { return ObjectFile::Atom::scopeTranslationUnit; }
 171         virtual DefinitionKind                                          getDefinitionKind() const       { return kRegularDefinition; }
 172         virtual SymbolTableInclusion                            getSymbolTableInclusion() const { return ObjectFile::Atom::kSymbolTableNotIn; }
 173         virtual bool                                                            dontDeadStrip() const           { return false; }
 174         virtual bool                                                            isZeroFill() const                      { return false; }
 175         virtual bool                                                            isThumb() const                         { return false; }
 176         virtual uint64_t                                                        getSize() const                         { return 0; }
 177         virtual std::vector<ObjectFile::Reference*>&  getReferences() const             { return (std::vector<ObjectFile::Reference*>&)(fReferences); }
 178         virtual bool                                                            mustRemainInSection() const { return false; }
 179         virtual const char*                                                     getSectionName() const          { return "._imports"; }
 180         virtual Segment&                                                        getSegment() const                      { return fgImportSegment; }
 181         virtual ObjectFile::Atom&                                       getFollowOnAtom() const         { return *((ObjectFile::Atom*)NULL); }
 182         virtual uint32_t                                                        getOrdinal() const                      { return fOrdinal; }
 183         virtual std::vector<ObjectFile::LineInfo>*      getLineInfo() const                     { return NULL; }
 184         virtual ObjectFile::Alignment                           getAlignment() const            { return ObjectFile::Alignment(0); }
 185         virtual void                                                            copyRawContent(uint8_t buffer[]) const  {}
 186
 187         virtual void                                                            setScope(Scope)                         { }
 188
 189 protected:
 190         friend class Reader<A>;
 191         typedef typename A::P                                   P;
 192
 193                                                                                         ImportAtom(ObjectFile::Reader& owner, uint32_t ordinal, std::vector<const char*>& imports)
 194                                                                                                 : fOwner(owner), fOrdinal(ordinal) { makeReferences(imports); }
 195         virtual                                                                 ~ImportAtom() {}
 196         void                                                                    makeReferences(std::vector<const char*>& imports) {
 197                                                                                                 for (std::vector<const char*>::iterator it=imports.begin(); it != imports.end(); ++it) {
 198                                                                                                         fReferences.push_back(new ImportReference(*it));
 199                                                                                                 }
 200                                                                                         }
 201
 202
 203         ObjectFile::Reader&                                             fOwner;
 204         uint32_t                                                                fOrdinal;
 205         std::vector<ObjectFile::Reference*>             fReferences;
 206
 207         static Segment                                                  fgImportSegment;
 208 };
 209
 210 template <typename A>
 211 Segment                                                         ImportAtom<A>::fgImportSegment("__LINKEDIT");
 212
 213
 214
 215
 216 //
 217 // The reader for a dylib extracts all exported symbols names from the memory-mapped
 218 // dylib, builds a hash table, then unmaps the file.  This is an important memory
 219 // savings for large dylibs.
 220 //
 221 template <typename A>
 222 class Reader : public ObjectFile::Reader
 223 {
 224 public:
 225         static bool                                                                             validFile(const uint8_t* fileContent, bool executableOrDylib);
 226                                                                                                         Reader(const uint8_t* fileContent, uint64_t fileLength, const char* path,
 227                                                                                                                 const LibraryOptions& dylibOptions, const ObjectFile::ReaderOptions& options,
 228                                                                                                                 uint32_t ordinalBase);
 229         virtual                                                                                 ~Reader() {}
 230
 231         virtual const char*                                                             getPath()                                       { return fPath; }
 232         virtual time_t                                                                  getModificationTime()           { return 0; }
 233         virtual DebugInfoKind                                                   getDebugInfoKind()                      { return ObjectFile::Reader::kDebugInfoNone; }
 234         virtual std::vector<class ObjectFile::Atom*>&   getAtoms();
 235         virtual std::vector<class ObjectFile::Atom*>*   getJustInTimeAtomsFor(const char* name);
 236         virtual std::vector<Stab>*                                              getStabs()                                      { return NULL; }
 237         virtual ObjectFile::Reader::ObjcConstraint              getObjCConstraint()                     { return fObjcContraint; }
 238         virtual const char*                                                             getInstallPath()                        { return fDylibInstallPath; }
 239         virtual uint32_t                                                                getTimestamp()                          { return fDylibTimeStamp; }
 240         virtual uint32_t                                                                getCurrentVersion()                     { return fDylibtCurrentVersion; }
 241         virtual uint32_t                                                                getCompatibilityVersion()       { return fDylibCompatibilityVersion; }
 242         virtual void                                                                    processIndirectLibraries(DylibHander* handler);
 243         virtual void                                                                    setExplicitlyLinked()           { fExplicitlyLinked = true; }
 244         virtual bool                                                                    explicitlyLinked()                      { return fExplicitlyLinked; }
 245         virtual bool                                                                    implicitlyLinked()                      { return fImplicitlyLinked; }
 246         virtual bool                                                                    providedExportAtom()            { return fProvidedAtom; }
 247         virtual const char*                                                             parentUmbrella()                        { return fParentUmbrella; }
 248         virtual std::vector<const char*>*                               getAllowableClients();
 249         virtual bool                                                                    hasWeakExternals()                      { return fHasWeakExports; }
 250         virtual bool                                                                    deadStrippable()                        { return fDeadStrippable; }
 251         virtual bool                                                                    isLazyLoadedDylib()                     { return fLazyLoaded; }
 252
 253         virtual void                                                                    setImplicitlyLinked()           { fImplicitlyLinked = true; }
 254
 255 protected:
 256
 257         struct ReExportChain { ReExportChain* prev; Reader<A>* reader; };
 258
 259         void                                                                                    assertNoReExportCycles(ReExportChain*);
 260
 261 private:
 262         typedef typename A::P                                           P;
 263         typedef typename A::P::E                                        E;
 264
 265         class CStringEquals
 266         {
 267         public:
 268                 bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
 269         };
 270         struct AtomAndWeak { ObjectFile::Atom* atom; bool weak; uint32_t ordinal; };
 271         typedef __gnu_cxx::hash_map<const char*, AtomAndWeak, __gnu_cxx::hash<const char*>, CStringEquals> NameToAtomMap;
 272         typedef __gnu_cxx::hash_set<const char*, __gnu_cxx::hash<const char*>, CStringEquals>  NameSet;
 273         typedef typename NameToAtomMap::iterator                NameToAtomMapIterator;
 274
 275         struct PathAndFlag { const char* path; bool reExport; };
 276
 277         bool                                                                            isPublicLocation(const char* path);
 278         void                                                                            addSymbol(const char* name, bool weak);
 279         void                                                                            addDyldFastStub();
 280         void                                                                            buildExportHashTableFromExportInfo(const macho_dyld_info_command<P>* dyldInfo,
 281                                                                                                                                                                 const uint8_t* fileContent);
 282         void                                                                            buildExportHashTableFromSymbolTable(const macho_dysymtab_command<P>* dynamicInfo,
 283                                                                                                                 const macho_nlist<P>* symbolTable, const char* strings,
 284                                                                                                                 const uint8_t* fileContent);
 285
 286         const char*                                                                     fPath;
 287         const char*                                                                     fParentUmbrella;
 288         std::vector<const char*>                                        fAllowableClients;
 289         const char*                                                                     fDylibInstallPath;
 290         uint32_t                                                                        fDylibTimeStamp;
 291         uint32_t                                                                        fDylibtCurrentVersion;
 292         uint32_t                                                                        fDylibCompatibilityVersion;
 293         uint32_t                                                                        fReExportedOrdinal;
 294         std::vector<PathAndFlag>                                        fDependentLibraryPaths;
 295         NameToAtomMap                                                           fAtoms;
 296         NameSet                                                                         fIgnoreExports;
 297         bool                                                                            fNoRexports;
 298         bool                                                                            fHasWeakExports;
 299         bool                                                                            fDeadStrippable;
 300         const bool                                                                      fLinkingFlat;
 301         const bool                                                                      fLinkingMainExecutable;
 302         bool                                                                            fExplictReExportFound;
 303         bool                                                                            fExplicitlyLinked;
 304         bool                                                                            fImplicitlyLinked;
 305         bool                                                                            fProvidedAtom;
 306         bool                                                                            fImplicitlyLinkPublicDylibs;
 307         bool                                                                            fLazyLoaded;
 308         ObjectFile::Reader::ObjcConstraint                      fObjcContraint;
 309         std::vector<ObjectFile::Reader*>                        fReExportedChildren;
 310         const ObjectFile::ReaderOptions::MacVersionMin  fDeploymentVersionMin;
 311         std::vector<class ObjectFile::Atom*>            fFlatImports;
 312
 313         static bool                                                                     fgLogHashtable;
 314         static std::vector<class ObjectFile::Atom*>     fgEmptyAtomList;
 315 };
 316
 317 template <typename A>
 318 std::vector<class ObjectFile::Atom*>    Reader<A>::fgEmptyAtomList;
 319 template <typename A>
 320 bool                                                                    Reader<A>::fgLogHashtable = false;
 321
 322
 323 template <typename A>
 324 Reader<A>::Reader(const uint8_t* fileContent, uint64_t fileLength, const char* path,
 325                 const LibraryOptions& dylibOptions,
 326                 const ObjectFile::ReaderOptions& options, uint32_t ordinalBase)
 327         : fParentUmbrella(NULL), fDylibInstallPath(NULL), fDylibTimeStamp(0), fDylibtCurrentVersion(0),
 328         fDylibCompatibilityVersion(0), fReExportedOrdinal(ordinalBase), fLinkingFlat(options.fFlatNamespace),
 329         fLinkingMainExecutable(options.fLinkingMainExecutable), fExplictReExportFound(false),
 330         fExplicitlyLinked(false), fImplicitlyLinked(false), fProvidedAtom(false),
 331         fImplicitlyLinkPublicDylibs(options.fImplicitlyLinkPublicDylibs), fLazyLoaded(dylibOptions.fLazyLoad),
 332         fObjcContraint(ObjectFile::Reader::kObjcNone),
 333         fDeploymentVersionMin(options.fMacVersionMin)
 334 {
 335         // sanity check
 336         if ( ! validFile(fileContent, dylibOptions.fBundleLoader) )
 337                 throw "not a valid mach-o object file";
 338
 339         fPath = strdup(path);
 340
 341         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 342         const uint32_t cmd_count = header->ncmds();
 343         const macho_load_command<P>* const cmds = (macho_load_command<P>*)((char*)header + sizeof(macho_header<P>));
 344         const macho_load_command<P>* const cmdsEnd = (macho_load_command<P>*)((char*)header + sizeof(macho_header<P>) + header->sizeofcmds());
 345
 346         // write out path for -whatsloaded option
 347         if ( options.fLogAllFiles )
 348                 printf("%s\n", path);
 349
 350         if ( options.fRootSafe && ((header->flags() & MH_ROOT_SAFE) == 0) )
 351                 warning("using -root_safe but linking against %s which is not root safe", path);
 352
 353         if ( options.fSetuidSafe && ((header->flags() & MH_SETUID_SAFE) == 0) )
 354                 warning("using -setuid_safe but linking against %s which is not setuid safe", path);
 355
 356         // a "blank" stub has zero load commands
 357         if ( (header->filetype() == MH_DYLIB_STUB) && (cmd_count == 0) ) {
 358                 // no further processing needed
 359                 munmap((caddr_t)fileContent, fileLength);
 360                 return;
 361         }
 362
 363
 364         // optimize the case where we know there is no reason to look at indirect dylibs
 365         fNoRexports = (header->flags() & MH_NO_REEXPORTED_DYLIBS);
 366         fHasWeakExports = (header->flags() & MH_WEAK_DEFINES);
 367         fDeadStrippable = (header->flags() & MH_DEAD_STRIPPABLE_DYLIB);
 368         bool trackDependentLibraries = !fNoRexports || options.fFlatNamespace;
 369
 370         // pass 1 builds list of all dependent libraries
 371         const macho_load_command<P>* cmd = cmds;
 372         if ( trackDependentLibraries ) {
 373                 for (uint32_t i = 0; i < cmd_count; ++i) {
 374                         switch (cmd->cmd()) {
 375                                 case LC_REEXPORT_DYLIB:
 376                                         fExplictReExportFound = true;
 377                                         // fall into next case
 378                                 case LC_LOAD_DYLIB:
 379                                 case LC_LOAD_WEAK_DYLIB:
 380                                         PathAndFlag entry;
 381                                         entry.path = strdup(((struct macho_dylib_command<P>*)cmd)->name());
 382                                         entry.reExport = (cmd->cmd() == LC_REEXPORT_DYLIB);
 383                                         fDependentLibraryPaths.push_back(entry);
 384                                         break;
 385                         }
 386                         cmd = (const macho_load_command<P>*)(((char*)cmd)+cmd->cmdsize());
 387                         if ( cmd > cmdsEnd )
 388                                 throwf("malformed dylb, load command #%d is outside size of load commands in %s", i, path);
 389                 }
 390         }
 391
 392         // pass 2 determines re-export info
 393         const macho_dysymtab_command<P>* dynamicInfo = NULL;
 394         const macho_dyld_info_command<P>* dyldInfo = NULL;
 395         const macho_nlist<P>* symbolTable = NULL;
 396         const char*     strings = NULL;
 397         cmd = cmds;
 398         for (uint32_t i = 0; i < cmd_count; ++i) {
 399                 switch (cmd->cmd()) {
 400                         case LC_SYMTAB:
 401                                 {
 402                                         const macho_symtab_command<P>* symtab = (macho_symtab_command<P>*)cmd;
 403                                         symbolTable = (const macho_nlist<P>*)((char*)header + symtab->symoff());
 404                                         strings = (char*)header + symtab->stroff();
 405                                 }
 406                                 break;
 407                         case LC_DYSYMTAB:
 408                                 dynamicInfo = (macho_dysymtab_command<P>*)cmd;
 409                                 break;
 410                         case LC_DYLD_INFO:
 411                         case LC_DYLD_INFO_ONLY:
 412                                 dyldInfo = (macho_dyld_info_command<P>*)cmd;
 413                                 break;
 414                         case LC_ID_DYLIB:
 415                                 {
 416                                 macho_dylib_command<P>* dylibID = (macho_dylib_command<P>*)cmd;
 417                                 fDylibInstallPath                       = strdup(dylibID->name());
 418                                 fDylibTimeStamp                         = dylibID->timestamp();
 419                                 fDylibtCurrentVersion           = dylibID->current_version();
 420                                 fDylibCompatibilityVersion      = dylibID->compatibility_version();
 421                                 }
 422                                 break;
 423                         case LC_SUB_UMBRELLA:
 424                                 if ( trackDependentLibraries ) {
 425                                         const char* frameworkLeafName = ((macho_sub_umbrella_command<P>*)cmd)->sub_umbrella();
 426                                         for (typename std::vector<PathAndFlag>::iterator it = fDependentLibraryPaths.begin(); it != fDependentLibraryPaths.end(); it++) {
 427                                                 const char* dylibName = it->path;
 428                                                 const char* lastSlash = strrchr(dylibName, '/');
 429                                                 if ( (lastSlash != NULL) && (strcmp(&lastSlash[1], frameworkLeafName) == 0) )
 430                                                         it->reExport = true;
 431                                         }
 432                                 }
 433                                 break;
 434                         case LC_SUB_LIBRARY:
 435                                 if ( trackDependentLibraries) {
 436                                         const char* dylibBaseName = ((macho_sub_library_command<P>*)cmd)->sub_library();
 437                                         for (typename std::vector<PathAndFlag>::iterator it = fDependentLibraryPaths.begin(); it != fDependentLibraryPaths.end(); it++) {
 438                                                 const char* dylibName = it->path;
 439                                                 const char* lastSlash = strrchr(dylibName, '/');
 440                                                 const char* leafStart = &lastSlash[1];
 441                                                 if ( lastSlash == NULL )
 442                                                         leafStart = dylibName;
 443                                                 const char* firstDot = strchr(leafStart, '.');
 444                                                 int len = strlen(leafStart);
 445                                                 if ( firstDot != NULL )
 446                                                         len = firstDot - leafStart;
 447                                                 if ( strncmp(leafStart, dylibBaseName, len) == 0 )
 448                                                         it->reExport = true;
 449                                         }
 450                                 }
 451                                 break;
 452                         case LC_SUB_FRAMEWORK:
 453                                 fParentUmbrella = strdup(((macho_sub_framework_command<P>*)cmd)->umbrella());
 454                                 break;
 455                         case macho_segment_command<P>::CMD:
 456                                 // check for Objective-C info
 457                                 if ( strcmp(((macho_segment_command<P>*)cmd)->segname(), "__OBJC") == 0 ) {
 458                                         const macho_segment_command<P>* segment = (macho_segment_command<P>*)cmd;
 459                                         const macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)segment + sizeof(macho_segment_command<P>));
 460                                         const macho_section<P>* const sectionsEnd = &sectionsStart[segment->nsects()];
 461                                         for (const macho_section<P>* sect=sectionsStart; sect < sectionsEnd; ++sect) {
 462                                                         if ( strcmp(sect->sectname(), "__image_info") == 0 ) {
 463                                                         //      struct objc_image_info  {
 464                                                         //              uint32_t        version;        // initially 0
 465                                                         //              uint32_t        flags;
 466                                                         //      };
 467                                                         // #define OBJC_IMAGE_SUPPORTS_GC   2
 468                                                         // #define OBJC_IMAGE_GC_ONLY       4
 469                                                         //
 470                                                         const uint32_t* contents = (uint32_t*)(&fileContent[sect->offset()]);
 471                                                         if ( (sect->size() >= 8) && (contents[0] == 0) ) {
 472                                                                 uint32_t flags = E::get32(contents[1]);
 473                                                                 if ( (flags & 4) == 4 )
 474                                                                         fObjcContraint = ObjectFile::Reader::kObjcGC;
 475                                                                 else if ( (flags & 2) == 2 )
 476                                                                         fObjcContraint = ObjectFile::Reader::kObjcRetainReleaseOrGC;
 477                                                                 else
 478                                                                         fObjcContraint = ObjectFile::Reader::kObjcRetainRelease;
 479                                                         }
 480                                                         else if ( sect->size() > 0 ) {
 481                                                                 warning("can't parse __OBJC/__image_info section in %s", fPath);
 482                                                         }
 483                                                 }
 484                                         }
 485                                 }
 486                 }
 487
 488                 cmd = (const macho_load_command<P>*)(((char*)cmd)+cmd->cmdsize());
 489                 if ( cmd > cmdsEnd )
 490                         throwf("malformed dylb, load command #%d is outside size of load commands in %s", i, path);
 491         }
 492
 493         // Process the rest of the commands here.
 494         cmd = cmds;
 495         for (uint32_t i = 0; i < cmd_count; ++i) {
 496                 switch (cmd->cmd()) {
 497                 case LC_SUB_CLIENT:
 498                         const char *temp = strdup(((macho_sub_client_command<P>*)cmd)->client());
 499                         fAllowableClients.push_back(temp);
 500                         break;
 501                 }
 502                 cmd = (const macho_load_command<P>*)(((char*)cmd)+cmd->cmdsize());
 503         }
 504
 505         // validate minimal load commands
 506         if ( (fDylibInstallPath == NULL) && ((header->filetype() == MH_DYLIB) || (header->filetype() == MH_DYLIB_STUB)) )
 507                 throwf("dylib %s missing LC_ID_DYLIB load command", path);
 508         if ( symbolTable == NULL )
 509                 throw "binary missing LC_SYMTAB load command";
 510         if ( dynamicInfo == NULL )
 511                 throw "binary missing LC_DYSYMTAB load command";
 512
 513         // if linking flat and this is a flat dylib, create one atom that references all imported symbols
 514         if ( fLinkingFlat && fLinkingMainExecutable && ((header->flags() & MH_TWOLEVEL) == 0) ) {
 515                 std::vector<const char*> importNames;
 516                 importNames.reserve(dynamicInfo->nundefsym());
 517                 const macho_nlist<P>* start = &symbolTable[dynamicInfo->iundefsym()];
 518                 const macho_nlist<P>* end = &start[dynamicInfo->nundefsym()];
 519                 for (const macho_nlist<P>* sym=start; sym < end; ++sym) {
 520                         importNames.push_back(&strings[sym->n_strx()]);
 521                 }
 522                 fFlatImports.push_back(new ImportAtom<A>(*this, fReExportedOrdinal++, importNames));
 523         }
 524
 525         // build hash table
 526         if ( dyldInfo != NULL )
 527                 buildExportHashTableFromExportInfo(dyldInfo, fileContent);
 528         else
 529                 buildExportHashTableFromSymbolTable(dynamicInfo, symbolTable, strings, fileContent);
 530
 531         // special case libSystem
 532         if ( (fDylibInstallPath != NULL) && (strcmp(fDylibInstallPath, "/usr/lib/libSystem.B.dylib") == 0) )
 533                 addDyldFastStub();
 534
 535         // unmap file
 536         munmap((caddr_t)fileContent, fileLength);
 537 }
 538
 539
 540 template <typename A>
 541 void Reader<A>::buildExportHashTableFromSymbolTable(const macho_dysymtab_command<P>* dynamicInfo,
 542                                                                                                 const macho_nlist<P>* symbolTable, const char* strings,
 543                                                                                                 const uint8_t* fileContent)
 544 {
 545         if ( dynamicInfo->tocoff() == 0 ) {
 546                 if ( fgLogHashtable ) fprintf(stderr, "ld: building hashtable of %u toc entries for %s\n", dynamicInfo->nextdefsym(), this->getPath());
 547                 const macho_nlist<P>* start = &symbolTable[dynamicInfo->iextdefsym()];
 548                 const macho_nlist<P>* end = &start[dynamicInfo->nextdefsym()];
 549                 fAtoms.resize(dynamicInfo->nextdefsym()); // set initial bucket count
 550                 for (const macho_nlist<P>* sym=start; sym < end; ++sym) {
 551                         this->addSymbol(&strings[sym->n_strx()], (sym->n_desc() & N_WEAK_DEF) != 0);
 552                 }
 553         }
 554         else {
 555                 int32_t count = dynamicInfo->ntoc();
 556                 fAtoms.resize(count); // set initial bucket count
 557                 if ( fgLogHashtable ) fprintf(stderr, "ld: building hashtable of %u entries for %s\n", count, this->getPath());
 558                 const struct dylib_table_of_contents* toc = (dylib_table_of_contents*)(fileContent + dynamicInfo->tocoff());
 559                 for (int32_t i = 0; i < count; ++i) {
 560                         const uint32_t index = E::get32(toc[i].symbol_index);
 561                         const macho_nlist<P>* sym = &symbolTable[index];
 562                         this->addSymbol(&strings[sym->n_strx()], (sym->n_desc() & N_WEAK_DEF) != 0);
 563                 }
 564         }
 565 }
 566
 567
 568 template <typename A>
 569 void Reader<A>::buildExportHashTableFromExportInfo(const macho_dyld_info_command<P>* dyldInfo,
 570                                                                                                                                 const uint8_t* fileContent)
 571 {
 572         if ( fgLogHashtable ) fprintf(stderr, "ld: building hashtable from export info in %s\n", this->getPath());
 573         if ( dyldInfo->export_size() > 0 ) {
 574                 const uint8_t* start = fileContent + dyldInfo->export_off();
 575                 const uint8_t* end = &start[dyldInfo->export_size()];
 576                 std::vector<mach_o::trie::Entry> list;
 577                 parseTrie(start, end, list);
 578                 for (std::vector<mach_o::trie::Entry>::iterator it=list.begin(); it != list.end(); ++it)
 579                         this->addSymbol(it->name, it->flags & EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION);
 580         }
 581 }
 582
 583
 584 template <>
 585 void Reader<x86_64>::addDyldFastStub()
 586 {
 587         addSymbol("dyld_stub_binder", false);
 588 }
 589
 590 template <>
 591 void Reader<x86>::addDyldFastStub()
 592 {
 593         addSymbol("dyld_stub_binder", false);
 594 }
 595
 596 template <typename A>
 597 void Reader<A>::addDyldFastStub()
 598 {
 599         // do nothing
 600 }
 601
 602 template <typename A>
 603 void Reader<A>::addSymbol(const char* name, bool weakDef)
 604 {
 605         //fprintf(stderr, "addSymbol() %s\n", name);
 606         // symbols that start with $ld$ are meta-data to the static linker
 607         // <rdar://problem/5182537> need way for ld and dyld to see different exported symbols in a dylib
 608         if ( strncmp(name, "$ld$", 4) == 0 ) {
 609                 //    $ld$ <action> $ <condition> $ <symbol-name>
 610                 const char* symAction = &name[4];
 611                 const char* symCond = strchr(symAction, '$');
 612                 if ( symCond != NULL ) {
 613                         ObjectFile::ReaderOptions::MacVersionMin symVersionCondition = ObjectFile::ReaderOptions::kMinMacVersionUnset;
 614                         if ( (strncmp(symCond, "$os10.", 6) == 0) && isdigit(symCond[6]) && (symCond[7] == '$') ) {
 615                                 switch ( symCond[6] - '0' ) {
 616                                         case 0:
 617                                         case 1:
 618                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_1;
 619                                                 break;
 620                                         case 2:
 621                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_2;
 622                                                 break;
 623                                         case 3:
 624                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_3;
 625                                                 break;
 626                                         case 4:
 627                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_4;
 628                                                 break;
 629                                         case 5:
 630                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_5;
 631                                                 break;
 632                                         case 6:
 633                                                 symVersionCondition = ObjectFile::ReaderOptions::k10_6;
 634                                                 break;
 635                                 }
 636                                 const char* symName = strchr(&symCond[1], '$');
 637                                 if ( symName != NULL ) {
 638                                         ++symName;
 639                                         if ( fDeploymentVersionMin == symVersionCondition ) {
 640                                                 if ( strncmp(symAction, "hide$", 5) == 0 ) {
 641                                                         if ( fgLogHashtable ) fprintf(stderr, "  adding %s to ignore set for %s\n", symName, this->getPath());
 642                                                         fIgnoreExports.insert(strdup(symName));
 643                                                         return;
 644                                                 }
 645                                                 else if ( strncmp(symAction, "add$", 4) == 0 ) {
 646                                                         this->addSymbol(symName, weakDef);
 647                                                         return;
 648                                                 }
 649                                                 else {
 650                                                         warning("bad symbol action: %s in dylib %s", name, this->getPath());
 651                                                 }
 652                                         }
 653                                 }
 654                                 else {
 655                                         warning("bad symbol name: %s in dylib %s", name, this->getPath());
 656                                 }
 657                         }
 658                         else {
 659                                 warning("bad symbol version: %s in dylib %s", name, this->getPath());
 660                         }
 661                 }
 662                 else {
 663                         warning("bad symbol condition: %s in dylib %s", name, this->getPath());
 664                 }
 665         }
 666
 667         // add symbol as possible export if we are not supposed to ignore it
 668         if ( fIgnoreExports.count(name) == 0 ) {
 669                 AtomAndWeak bucket;
 670                 bucket.atom = NULL;
 671                 bucket.weak = weakDef;
 672                 bucket.ordinal = fReExportedOrdinal++;
 673                 if ( fgLogHashtable ) fprintf(stderr, "  adding %s to hash table for %s\n", name, this->getPath());
 674                 fAtoms[strdup(name)] = bucket;
 675         }
 676 }
 677
 678
 679 template <typename A>
 680 std::vector<class ObjectFile::Atom*>& Reader<A>::getAtoms()
 681 {
 682         return fFlatImports;
 683 }
 684
 685
 686 template <typename A>
 687 std::vector<class ObjectFile::Atom*>* Reader<A>::getJustInTimeAtomsFor(const char* name)
 688 {
 689         // if supposed to ignore this export, then pretend I don't have it
 690         if ( fIgnoreExports.count(name) != 0 )
 691                 return NULL;
 692
 693         std::vector<class ObjectFile::Atom*>* atoms = NULL;
 694         NameToAtomMapIterator pos = fAtoms.find(name);
 695         if ( pos != fAtoms.end() ) {
 696                 if ( pos->second.atom == NULL ) {
 697                         // instantiate atom and update hash table
 698                         pos->second.atom = new ExportAtom<A>(*this, name, pos->second.weak, pos->second.ordinal);
 699                         fProvidedAtom = true;
 700                         if ( fgLogHashtable ) fprintf(stderr, "getJustInTimeAtomsFor: %s found in %s\n", name, this->getPath());
 701                 }
 702                 // return a vector of one atom
 703                 atoms = new std::vector<class ObjectFile::Atom*>;
 704                 atoms->push_back(pos->second.atom);
 705         }
 706         else {
 707                 if ( fgLogHashtable ) fprintf(stderr, "getJustInTimeAtomsFor: %s NOT found in %s\n", name, this->getPath());
 708                 // look in children that I re-export
 709                 for (std::vector<ObjectFile::Reader*>::iterator it = fReExportedChildren.begin(); it != fReExportedChildren.end(); it++) {
 710                         //fprintf(stderr, "getJustInTimeAtomsFor: %s NOT found in %s, looking in child %s\n", name, this->getPath(), (*it)->getInstallPath());
 711                         std::vector<class ObjectFile::Atom*>* childAtoms = (*it)->getJustInTimeAtomsFor(name);
 712                         if ( childAtoms != NULL ) {
 713                                 // make a new atom that says this reader is the owner
 714                                 bool isWeakDef = (childAtoms->at(0)->getDefinitionKind() == ObjectFile::Atom::kExternalWeakDefinition);
 715                                 // return a vector of one atom
 716                                 ExportAtom<A>* newAtom = new ExportAtom<A>(*this, name, isWeakDef, fReExportedOrdinal++);
 717                                 fProvidedAtom = true;
 718                                 atoms = new std::vector<class ObjectFile::Atom*>;
 719                                 atoms->push_back(newAtom);
 720                                 delete childAtoms;
 721                                 return atoms;
 722                         }
 723                 }
 724         }
 725         return atoms;
 726 }
 727
 728
 729
 730 template <typename A>
 731 bool Reader<A>::isPublicLocation(const char* path)
 732 {
 733         // -no_implicit_dylibs disables this optimization
 734         if ( ! fImplicitlyLinkPublicDylibs )
 735                 return false;
 736
 737         // /usr/lib is a public location
 738         if ( (strncmp(path, "/usr/lib/", 9) == 0) && (strchr(&path[9], '/') == NULL) )
 739                 return true;
 740
 741         // /System/Library/Frameworks/ is a public location
 742         if ( strncmp(path, "/System/Library/Frameworks/", 27) == 0 ) {
 743                 const char* frameworkDot = strchr(&path[27], '.');
 744                 // but only top level framework
 745                 // /System/Library/Frameworks/Foo.framework/Versions/A/Foo                 ==> true
 746                 // /System/Library/Frameworks/Foo.framework/Resources/libBar.dylib         ==> false
 747                 // /System/Library/Frameworks/Foo.framework/Frameworks/Bar.framework/Bar   ==> false
 748                 // /System/Library/Frameworks/Foo.framework/Frameworks/Xfoo.framework/XFoo ==> false
 749                 if ( frameworkDot != NULL ) {
 750                         int frameworkNameLen = frameworkDot - &path[27];
 751                         if ( strncmp(&path[strlen(path)-frameworkNameLen-1], &path[26], frameworkNameLen+1) == 0 )
 752                                 return true;
 753                 }
 754         }
 755
 756         return false;
 757 }
 758
 759 template <typename A>
 760 void Reader<A>::processIndirectLibraries(DylibHander* handler)
 761 {
 762         if ( fLinkingFlat ) {
 763                 for (typename std::vector<PathAndFlag>::iterator it = fDependentLibraryPaths.begin(); it != fDependentLibraryPaths.end(); it++) {
 764                         handler->findDylib(it->path, this->getPath());
 765                 }
 766         }
 767         else if ( fNoRexports ) {
 768                 // MH_NO_REEXPORTED_DYLIBS bit set, then nothing to do
 769         }
 770         else {
 771                 // two-level, might have re-exports
 772                 for (typename std::vector<PathAndFlag>::iterator it = fDependentLibraryPaths.begin(); it != fDependentLibraryPaths.end(); it++) {
 773                         if ( it->reExport ) {
 774                                 //fprintf(stderr, "processIndirectLibraries() parent=%s, child=%s\n", this->getInstallPath(), it->path);
 775                                 // a LC_REEXPORT_DYLIB, LC_SUB_UMBRELLA or LC_SUB_LIBRARY says we re-export this child
 776                                 ObjectFile::Reader* child = handler->findDylib(it->path, this->getPath());
 777                                 if ( isPublicLocation(child->getInstallPath()) ) {
 778                                         // promote this child to be automatically added as a direct dependent if this already is
 779                                         if ( this->explicitlyLinked() || this->implicitlyLinked() ) {
 780                                                 //fprintf(stderr, "processIndirectLibraries() implicitly linking %s\n", child->getInstallPath());
 781                                                 ((Reader<A>*)child)->setImplicitlyLinked();
 782                                         }
 783                                         else if ( child->explicitlyLinked() || child->implicitlyLinked() ) {
 784                                                 //fprintf(stderr, "processIndirectLibraries() parent is not directly linked, but child is, so no need to re-export child\n");
 785                                         }
 786                                         else {
 787                                                 fReExportedChildren.push_back(child);
 788                                                 //fprintf(stderr, "processIndirectLibraries() parent is not directly linked, so parent=%s will re-export child=%s\n", this->getInstallPath(), it->path);
 789                                         }
 790                                 }
 791                                 else {
 792                                         // add all child's symbols to me
 793                                         fReExportedChildren.push_back(child);
 794                                         //fprintf(stderr, "processIndirectLibraries() child is not public, so parent=%s will re-export child=%s\n", this->getInstallPath(), it->path);
 795                                 }
 796                         }
 797                         else if ( !fExplictReExportFound ) {
 798                                 // see if child contains LC_SUB_FRAMEWORK with my name
 799                                 ObjectFile::Reader* child = handler->findDylib(it->path, this->getPath());
 800                                 const char* parentUmbrellaName = ((Reader<A>*)child)->parentUmbrella();
 801                                 if ( parentUmbrellaName != NULL ) {
 802                                         const char* parentName = this->getPath();
 803                                         const char* lastSlash = strrchr(parentName, '/');
 804                                         if ( (lastSlash != NULL) && (strcmp(&lastSlash[1], parentUmbrellaName) == 0) ) {
 805                                                 // add all child's symbols to me
 806                                                 fReExportedChildren.push_back(child);
 807                                                 //fprintf(stderr, "processIndirectLibraries() umbrella=%s will re-export child=%s\n", this->getInstallPath(), it->path);
 808                                         }
 809                                 }
 810                         }
 811                 }
 812         }
 813
 814         // check for re-export cycles
 815         ReExportChain chain;
 816         chain.prev = NULL;
 817         chain.reader = this;
 818         this->assertNoReExportCycles(&chain);
 819 }
 820
 821 template <typename A>
 822 void Reader<A>::assertNoReExportCycles(ReExportChain* prev)
 823 {
 824         // recursively check my re-exported dylibs
 825         ReExportChain chain;
 826         chain.prev = prev;
 827         chain.reader = this;
 828         for (std::vector<ObjectFile::Reader*>::iterator it = fReExportedChildren.begin(); it != fReExportedChildren.end(); it++) {
 829                 ObjectFile::Reader* child = *it;
 830                 // check child is not already in chain
 831                 for (ReExportChain* p = prev; p != NULL; p = p->prev) {
 832                         if ( p->reader == child ) {
 833                                 throwf("cycle in dylib re-exports with %s", child->getPath());
 834                         }
 835                 }
 836                 ((Reader<A>*)(*it))->assertNoReExportCycles(&chain);
 837         }
 838 }
 839
 840
 841 template <typename A>
 842 std::vector<const char*>* Reader<A>::getAllowableClients()
 843 {
 844         std::vector<const char*>* result = new std::vector<const char*>;
 845         for (typename std::vector<const char*>::iterator it = fAllowableClients.begin();
 846                  it != fAllowableClients.end();
 847                  it++) {
 848                 result->push_back(*it);
 849         }
 850         return (fAllowableClients.size() != 0 ? result : NULL);
 851 }
 852
 853 template <>
 854 bool Reader<ppc>::validFile(const uint8_t* fileContent, bool executableOrDyliborBundle)
 855 {
 856         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 857         if ( header->magic() != MH_MAGIC )
 858                 return false;
 859         if ( header->cputype() != CPU_TYPE_POWERPC )
 860                 return false;
 861         switch ( header->filetype() ) {
 862                 case MH_DYLIB:
 863                 case MH_DYLIB_STUB:
 864                         return true;
 865                 case MH_BUNDLE:
 866                         if ( executableOrDyliborBundle )
 867                                 return true;
 868                         else
 869                                 throw "can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB)";
 870                 case MH_EXECUTE:
 871                         if ( executableOrDyliborBundle )
 872                                 return true;
 873                         else
 874                                 throw "can't link with a main executable";
 875                 default:
 876                         return false;
 877         }
 878 }
 879
 880 template <>
 881 bool Reader<ppc64>::validFile(const uint8_t* fileContent, bool executableOrDyliborBundle)
 882 {
 883         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 884         if ( header->magic() != MH_MAGIC_64 )
 885                 return false;
 886         if ( header->cputype() != CPU_TYPE_POWERPC64 )
 887                 return false;
 888         switch ( header->filetype() ) {
 889                 case MH_DYLIB:
 890                 case MH_DYLIB_STUB:
 891                         return true;
 892                 case MH_BUNDLE:
 893                         if ( executableOrDyliborBundle )
 894                                 return true;
 895                         else
 896                                 throw "can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB)";
 897                 case MH_EXECUTE:
 898                         if ( executableOrDyliborBundle )
 899                                 return true;
 900                         else
 901                                 throw "can't link with a main executable";
 902                 default:
 903                         return false;
 904         }
 905 }
 906
 907 template <>
 908 bool Reader<x86>::validFile(const uint8_t* fileContent, bool executableOrDyliborBundle)
 909 {
 910         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 911         if ( header->magic() != MH_MAGIC )
 912                 return false;
 913         if ( header->cputype() != CPU_TYPE_I386 )
 914                 return false;
 915         switch ( header->filetype() ) {
 916                 case MH_DYLIB:
 917                 case MH_DYLIB_STUB:
 918                         return true;
 919                 case MH_BUNDLE:
 920                         if ( executableOrDyliborBundle )
 921                                 return true;
 922                         else
 923                                 throw "can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB)";
 924                 case MH_EXECUTE:
 925                         if ( executableOrDyliborBundle )
 926                                 return true;
 927                         else
 928                                 throw "can't link with a main executable";
 929                 default:
 930                         return false;
 931         }
 932 }
 933
 934 template <>
 935 bool Reader<x86_64>::validFile(const uint8_t* fileContent, bool executableOrDyliborBundle)
 936 {
 937         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 938         if ( header->magic() != MH_MAGIC_64 )
 939                 return false;
 940         if ( header->cputype() != CPU_TYPE_X86_64 )
 941                 return false;
 942         switch ( header->filetype() ) {
 943                 case MH_DYLIB:
 944                 case MH_DYLIB_STUB:
 945                         return true;
 946                 case MH_BUNDLE:
 947                         if ( executableOrDyliborBundle )
 948                                 return true;
 949                         else
 950                                 throw "can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB)";
 951                 case MH_EXECUTE:
 952                         if ( executableOrDyliborBundle )
 953                                 return true;
 954                         else
 955                                 throw "can't link with a main executable";
 956                 default:
 957                         return false;
 958         }
 959 }
 960
 961 template <>
 962 bool Reader<arm>::validFile(const uint8_t* fileContent, bool executableOrDyliborBundle)
 963 {
 964         const macho_header<P>* header = (const macho_header<P>*)fileContent;
 965         if ( header->magic() != MH_MAGIC )
 966                 return false;
 967         if ( header->cputype() != CPU_TYPE_ARM )
 968                 return false;
 969         switch ( header->filetype() ) {
 970                 case MH_DYLIB:
 971                 case MH_DYLIB_STUB:
 972                         return true;
 973                 case MH_BUNDLE:
 974                         if ( executableOrDyliborBundle )
 975                                 return true;
 976                         else
 977                                 throw "can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB)";
 978                 case MH_EXECUTE:
 979                         if ( executableOrDyliborBundle )
 980                                 return true;
 981                         else
 982                                 throw "can't link with a main executable";
 983                 default:
 984                         return false;
 985         }
 986 }
 987
 988 }; // namespace dylib
 989 }; // namespace mach_o
 990
 991
 992 #endif // __OBJECT_FILE_DYLIB_MACH_O__