ld64/src/ld/ld.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-*
   2  *
   3  * Copyright (c) 2005-2010 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,
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  19  * Please see the License for the specific language governing rights and
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  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24
  25 // start temp HACK for cross builds
  26 extern "C" double log2 ( double );
  27 //#define __MATH__
  28 // end temp HACK for cross builds
  29
  30
  31 #include <stdlib.h>
  32 #include <sys/types.h>
  33 #include <sys/stat.h>
  34 #include <sys/mman.h>
  35 #include <sys/sysctl.h>
  36 #include <fcntl.h>
  37 #include <errno.h>
  38 #include <limits.h>
  39 #include <unistd.h>
  40 #include <execinfo.h>
  41 #include <mach/mach_time.h>
  42 #include <mach/vm_statistics.h>
  43 #include <mach/mach_init.h>
  44 #include <mach/mach_host.h>
  45 #include <dlfcn.h>
  46 #include <mach-o/dyld.h>
  47 #include <dlfcn.h>
  48 #include <AvailabilityMacros.h>
  49
  50 #include <string>
  51 #include <map>
  52 #include <set>
  53 #include <string>
  54 #include <vector>
  55 #include <list>
  56 #include <algorithm>
  57 #include <ext/hash_map>
  58 #include <ext/hash_set>
  59 #include <cxxabi.h>
  60
  61 #include "Options.h"
  62
  63 #include "MachOFileAbstraction.hpp"
  64 #include "Architectures.hpp"
  65 #include "ld.hpp"
  66
  67 #include "InputFiles.h"
  68 #include "Resolver.h"
  69 #include "OutputFile.h"
  70
  71 #include "passes/stubs/make_stubs.h"
  72 #include "passes/dtrace_dof.h"
  73 #include "passes/got.h"
  74 #include "passes/tlvp.h"
  75 #include "passes/huge.h"
  76 #include "passes/compact_unwind.h"
  77 #include "passes/order_file.h"
  78 #include "passes/branch_island.h"
  79 #include "passes/branch_shim.h"
  80 #include "passes/objc.h"
  81 #include "passes/dylibs.h"
  82
  83 #include "parsers/archive_file.h"
  84 #include "parsers/macho_relocatable_file.h"
  85 #include "parsers/macho_dylib_file.h"
  86 #include "parsers/lto_file.h"
  87 #include "parsers/opaque_section_file.h"
  88
  89
  90 class InternalState : public ld::Internal
  91 {
  92 public:
  93                                                                                         InternalState(const Options& opts) : _options(opts) { }
  94         virtual ld::Internal::FinalSection*             addAtom(const ld::Atom& atom);
  95         virtual ld::Internal::FinalSection*             getFinalSection(const ld::Section&);
  96
  97         void                                                                    sortSections();
  98         virtual                                                                 ~InternalState() {}
  99 private:
 100
 101         class FinalSection : public ld::Internal::FinalSection
 102         {
 103         public:
 104                                                         FinalSection(const ld::Section& sect, uint32_t sectionsSeen, bool objFile);
 105                 static int                                      sectionComparer(const void* l, const void* r);
 106                 static const ld::Section&       outputSection(const ld::Section& sect);
 107                 static const ld::Section&       objectOutputSection(const ld::Section& sect, bool makeTentativeDefsReal);
 108         private:
 109                 friend class InternalState;
 110                 static uint32_t         sectionOrder(const ld::Section& sect, uint32_t sectionsSeen);
 111                 static uint32_t         segmentOrder(const ld::Section& sect, bool objFile);
 112                 uint32_t                        _segmentOrder;
 113                 uint32_t                        _sectionOrder;
 114
 115                 static std::vector<const char*> _s_segmentsSeen;
 116                 static ld::Section              _s_DATA_data;
 117                 static ld::Section              _s_DATA_const;
 118                 static ld::Section              _s_TEXT_text;
 119                 static ld::Section              _s_TEXT_const;
 120                 static ld::Section              _s_DATA_nl_symbol_ptr;
 121                 static ld::Section              _s_DATA_common;
 122         };
 123
 124
 125         struct SectionHash {
 126                 size_t operator()(const ld::Section*) const;
 127         };
 128         struct SectionEquals {
 129                 bool operator()(const ld::Section* left, const ld::Section* right) const;
 130         };
 131         typedef __gnu_cxx::hash_map<const ld::Section*, FinalSection*, SectionHash, SectionEquals> SectionInToOut;
 132
 133
 134         SectionInToOut                  _sectionInToFinalMap;
 135         const Options&                  _options;
 136 };
 137
 138 ld::Section     InternalState::FinalSection::_s_DATA_data( "__DATA", "__data",  ld::Section::typeUnclassified);
 139 ld::Section     InternalState::FinalSection::_s_DATA_const("__DATA", "__const", ld::Section::typeUnclassified);
 140 ld::Section     InternalState::FinalSection::_s_TEXT_text( "__TEXT", "__text",  ld::Section::typeCode);
 141 ld::Section     InternalState::FinalSection::_s_TEXT_const("__TEXT", "__const", ld::Section::typeUnclassified);
 142 ld::Section     InternalState::FinalSection::_s_DATA_nl_symbol_ptr("__DATA", "__nl_symbol_ptr", ld::Section::typeNonLazyPointer);
 143 ld::Section     InternalState::FinalSection::_s_DATA_common("__DATA", "__common", ld::Section::typeZeroFill);
 144 std::vector<const char*> InternalState::FinalSection::_s_segmentsSeen;
 145
 146
 147 size_t InternalState::SectionHash::operator()(const ld::Section* sect) const
 148 {
 149         size_t hash = 0;
 150         __gnu_cxx::hash<const char*> temp;
 151         hash += temp.operator()(sect->segmentName());
 152         hash += temp.operator()(sect->sectionName());
 153         return hash;
 154 }
 155
 156 bool InternalState::SectionEquals::operator()(const ld::Section* left, const ld::Section* right) const
 157 {
 158         return (*left == *right);
 159 }
 160
 161
 162 InternalState::FinalSection::FinalSection(const ld::Section& sect, uint32_t sectionsSeen, bool objFile)
 163         : ld::Internal::FinalSection(sect),
 164           _segmentOrder(segmentOrder(sect, objFile)),
 165           _sectionOrder(sectionOrder(sect, sectionsSeen))
 166 {
 167         //fprintf(stderr, "FinalSection(%s, %s) _segmentOrder=%d, _sectionOrder=%d\n",
 168         //              this->segmentName(), this->sectionName(), _segmentOrder, _sectionOrder);
 169 }
 170
 171 const ld::Section& InternalState::FinalSection::outputSection(const ld::Section& sect)
 172 {
 173         // merge sections in final linked image
 174         switch ( sect.type() ) {
 175                 case ld::Section::typeLiteral4:
 176                 case ld::Section::typeLiteral8:
 177                 case ld::Section::typeLiteral16:
 178                         return _s_TEXT_const;
 179                 case ld::Section::typeUnclassified:
 180                         if ( strcmp(sect.segmentName(), "__DATA") == 0 ) {
 181                                 if ( strcmp(sect.sectionName(), "__datacoal_nt") == 0 )
 182                                         return _s_DATA_data;
 183                                 if ( strcmp(sect.sectionName(), "__const_coal") == 0 )
 184                                         return _s_DATA_const;
 185                         }
 186                         else if ( strcmp(sect.segmentName(), "__TEXT") == 0 ) {
 187                                 if ( strcmp(sect.sectionName(), "__const_coal") == 0 )
 188                                         return _s_TEXT_const;
 189                         }
 190                         break;
 191                 case ld::Section::typeCode:
 192                         if ( strcmp(sect.segmentName(), "__TEXT") == 0 ) {
 193                                 if ( strcmp(sect.sectionName(), "__textcoal_nt") == 0 )
 194                                         return _s_TEXT_text;
 195                                 else if ( strcmp(sect.sectionName(), "__StaticInit") == 0 )
 196                                         return _s_TEXT_text;
 197                         }
 198                         break;
 199                 case ld::Section::typeNonLazyPointer:
 200                         if ( strcmp(sect.segmentName(), "__DATA") == 0 ) {
 201                                 if ( strcmp(sect.sectionName(), "__nl_symbol_ptr") == 0 )
 202                                         return _s_DATA_nl_symbol_ptr;
 203                         }
 204                         else if ( strcmp(sect.segmentName(), "__IMPORT") == 0 ) {
 205                                 if ( strcmp(sect.sectionName(), "__pointers") == 0 )
 206                                         return _s_DATA_nl_symbol_ptr;
 207                         }
 208                         break;
 209                 case ld::Section::typeTentativeDefs:
 210                         return _s_DATA_common;
 211                         break;
 212                         // FIX ME: more
 213                 default:
 214                         break;
 215         }
 216         return sect;
 217 }
 218
 219 const ld::Section& InternalState::FinalSection::objectOutputSection(const ld::Section& sect, bool makeTentativeDefsReal)
 220 {
 221         // in -r mode the only section that ever changes is __tenative -> __common with -d option
 222         if ( (sect.type() == ld::Section::typeTentativeDefs) && makeTentativeDefsReal)
 223                 return _s_DATA_common;
 224         return sect;
 225 }
 226
 227 uint32_t InternalState::FinalSection::segmentOrder(const ld::Section& sect, bool objFile)
 228 {
 229         if ( strcmp(sect.segmentName(), "__PAGEZERO") == 0 )
 230                 return 0;
 231         if ( strcmp(sect.segmentName(), "__HEADER") == 0 ) // only used with -preload
 232                 return 0;
 233         if ( strcmp(sect.segmentName(), "__TEXT") == 0 )
 234                 return 1;
 235         // in -r mode, want __DATA  last so zerofill sections are at end
 236         if ( strcmp(sect.segmentName(), "__DATA") == 0 )
 237                 return (objFile ? 5 : 2);
 238         if ( strcmp(sect.segmentName(), "__OBJC") == 0 )
 239                 return 3;
 240         if ( strcmp(sect.segmentName(), "__IMPORT") == 0 )
 241                 return 4;
 242
 243         // layout non-standard segments in order seen (+10 to shift beyond standard segments)
 244         for (uint32_t i=0; i < _s_segmentsSeen.size(); ++i) {
 245                 if ( strcmp(_s_segmentsSeen[i], sect.segmentName()) == 0 )
 246                         return i+10;
 247         }
 248         _s_segmentsSeen.push_back(sect.segmentName());
 249         return _s_segmentsSeen.size()-1+10;
 250 }
 251
 252 uint32_t InternalState::FinalSection::sectionOrder(const ld::Section& sect, uint32_t sectionsSeen)
 253 {
 254         if ( sect.type() == ld::Section::typeFirstSection )
 255                 return 0;
 256         if ( sect.type() == ld::Section::typeMachHeader )
 257                 return 1;
 258         if ( sect.type() == ld::Section::typeLastSection )
 259                 return INT_MAX;
 260         if ( strcmp(sect.segmentName(), "__TEXT") == 0 ) {
 261                 switch ( sect.type() ) {
 262                         case ld::Section::typeCode:
 263                                 // <rdar://problem/8346444> make __text always be first "code" section
 264                                 if ( strcmp(sect.sectionName(), "__text") == 0 )
 265                                         return 10;
 266                                 else
 267                                         return 11;
 268                         case ld::Section::typeStub:
 269                                 return 12;
 270                         case ld::Section::typeStubHelper:
 271                                 return 13;
 272                         case ld::Section::typeLSDA:
 273                                 return INT_MAX-3;
 274                         case ld::Section::typeUnwindInfo:
 275                                 return INT_MAX-2;
 276                         case ld::Section::typeCFI:
 277                                 return INT_MAX-1;
 278                         case ld::Section::typeStubClose:
 279                                 return INT_MAX;
 280                         default:
 281                                 return sectionsSeen+20;
 282                 }
 283         }
 284         else if ( strcmp(sect.segmentName(), "__DATA") == 0 ) {
 285                 switch ( sect.type() ) {
 286                         case ld::Section::typeLazyPointerClose:
 287                                 return 8;
 288                         case ld::Section::typeDyldInfo:
 289                                 return 9;
 290                         case ld::Section::typeNonLazyPointer:
 291                                 return 10;
 292                         case ld::Section::typeLazyPointer:
 293                                 return 11;
 294                         case ld::Section::typeInitializerPointers:
 295                                 return 12;
 296                         case ld::Section::typeTerminatorPointers:
 297                                 return 13;
 298                         case ld::Section::typeTLVInitialValues:
 299                                 return INT_MAX-4; // need TLV zero-fill to follow TLV init values
 300                         case ld::Section::typeTLVZeroFill:
 301                                 return INT_MAX-3;
 302                         case ld::Section::typeZeroFill:
 303                                 // make sure __huge is always last zerofill section
 304                                 if ( strcmp(sect.sectionName(), "__huge") == 0 )
 305                                         return INT_MAX-1;
 306                                 else
 307                                         return INT_MAX-2;
 308                         default:
 309                                 // <rdar://problem/7435296> Reorder sections to reduce page faults in object files
 310                                 if ( strcmp(sect.sectionName(), "__objc_classlist") == 0 )
 311                                         return 20;
 312                                 else if ( strcmp(sect.sectionName(), "__objc_nlclslist") == 0 )
 313                                         return 21;
 314                                 else if ( strcmp(sect.sectionName(), "__objc_catlist") == 0 )
 315                                         return 22;
 316                                 else if ( strcmp(sect.sectionName(), "__objc_protolist") == 0 )
 317                                         return 23;
 318                                 else if ( strcmp(sect.sectionName(), "__objc_imageinfo") == 0 )
 319                                         return 24;
 320                                 else if ( strcmp(sect.sectionName(), "__objc_const") == 0 )
 321                                         return 25;
 322                                 else if ( strcmp(sect.sectionName(), "__objc_selrefs") == 0 )
 323                                         return 26;
 324                                 else if ( strcmp(sect.sectionName(), "__objc_msgrefs") == 0 )
 325                                         return 27;
 326                                 else if ( strcmp(sect.sectionName(), "__objc_protorefs") == 0 )
 327                                         return 28;
 328                                 else if ( strcmp(sect.sectionName(), "__objc_classrefs") == 0 )
 329                                         return 29;
 330                                 else if ( strcmp(sect.sectionName(), "__objc_superrefs") == 0 )
 331                                         return 30;
 332                                 else if ( strcmp(sect.sectionName(), "__objc_data") == 0 )
 333                                         return 31;
 334                                 else
 335                                         return sectionsSeen+40;
 336                 }
 337         }
 338         // make sure zerofill in any other section is at end of segment
 339         if ( sect.type() == ld::Section::typeZeroFill )
 340                 return INT_MAX-1;
 341         return sectionsSeen+20;
 342 }
 343
 344 #ifndef NDEBUG
 345 static void validateFixups(const ld::Atom& atom)
 346 {
 347         //fprintf(stderr, "validateFixups %s\n", atom.name());
 348         bool lastWasClusterEnd = true;
 349         ld::Fixup::Cluster lastClusterSize = ld::Fixup::k1of1;
 350         uint32_t curClusterOffsetInAtom = 0;
 351         for (ld::Fixup::iterator fit=atom.fixupsBegin(); fit != atom.fixupsEnd(); ++fit) {
 352                 //fprintf(stderr, "  fixup offset=%d, cluster=%d\n", fit->offsetInAtom, fit->clusterSize);
 353                 assert((fit->offsetInAtom < atom.size()) || (fit->offsetInAtom == 0));
 354                 if ( fit->firstInCluster() ) {
 355                         assert(lastWasClusterEnd);
 356                         curClusterOffsetInAtom = fit->offsetInAtom;
 357                         lastWasClusterEnd = (fit->clusterSize == ld::Fixup::k1of1);
 358                 }
 359                 else {
 360                         assert(!lastWasClusterEnd);
 361                         assert(fit->offsetInAtom == curClusterOffsetInAtom);
 362                         switch ((ld::Fixup::Cluster)fit->clusterSize) {
 363                                 case ld::Fixup::k1of1:
 364                                 case ld::Fixup::k1of2:
 365                                 case ld::Fixup::k1of3:
 366                                 case ld::Fixup::k1of4:
 367                                 case ld::Fixup::k1of5:
 368                                         lastWasClusterEnd = false;
 369                                         break;
 370                                 case ld::Fixup::k2of2:
 371                                         assert(lastClusterSize = ld::Fixup::k1of2);
 372                                         lastWasClusterEnd = true;
 373                                         break;
 374                                 case ld::Fixup::k2of3:
 375                                         assert(lastClusterSize = ld::Fixup::k1of3);
 376                                         lastWasClusterEnd = false;
 377                                         break;
 378                                 case ld::Fixup::k2of4:
 379                                         assert(lastClusterSize = ld::Fixup::k1of4);
 380                                         lastWasClusterEnd = false;
 381                                         break;
 382                                 case ld::Fixup::k2of5:
 383                                         assert(lastClusterSize = ld::Fixup::k1of5);
 384                                         lastWasClusterEnd = false;
 385                                         break;
 386                                 case ld::Fixup::k3of3:
 387                                         assert(lastClusterSize = ld::Fixup::k2of3);
 388                                         lastWasClusterEnd = true;
 389                                         break;
 390                                 case ld::Fixup::k3of4:
 391                                         assert(lastClusterSize = ld::Fixup::k2of4);
 392                                         lastWasClusterEnd = false;
 393                                         break;
 394                                 case ld::Fixup::k3of5:
 395                                         assert(lastClusterSize = ld::Fixup::k2of5);
 396                                         lastWasClusterEnd = false;
 397                                         break;
 398                                 case ld::Fixup::k4of4:
 399                                         assert(lastClusterSize = ld::Fixup::k3of4);
 400                                         lastWasClusterEnd = true;
 401                                         break;
 402                                 case ld::Fixup::k4of5:
 403                                         assert(lastClusterSize = ld::Fixup::k3of5);
 404                                         lastWasClusterEnd = false;
 405                                         break;
 406                                 case ld::Fixup::k5of5:
 407                                         assert(lastClusterSize = ld::Fixup::k4of5);
 408                                         lastWasClusterEnd = true;
 409                                         break;
 410                         }
 411                 }
 412                 lastClusterSize = fit->clusterSize;
 413                 if ( fit->binding == ld::Fixup::bindingDirectlyBound ) {
 414                         assert(fit->u.target != NULL);
 415                 }
 416         }
 417         switch (lastClusterSize) {
 418                 case ld::Fixup::k1of1:
 419                 case ld::Fixup::k2of2:
 420                 case ld::Fixup::k3of3:
 421                 case ld::Fixup::k4of4:
 422                 case ld::Fixup::k5of5:
 423                         break;
 424                 default:
 425                         assert(0 && "last fixup was not end of cluster");
 426                         break;
 427         }
 428 }
 429 #endif
 430
 431 ld::Internal::FinalSection* InternalState::addAtom(const ld::Atom& atom)
 432 {
 433         ld::Internal::FinalSection* fs = this->getFinalSection(atom.section());
 434
 435         // <rdar://problem/8612550> When order file used on data, turn ordered zero fill symbols into zero data
 436         switch ( atom.section().type() ) {
 437                 case ld::Section::typeZeroFill:
 438                 case ld::Section::typeTentativeDefs:
 439                         if ( (_options.outputKind() == Options::kDyld) && (atom.symbolTableInclusion() == ld::Atom::symbolTableIn)
 440                                         && (atom.size() <= 512) && (_options.orderedSymbolsCount() != 0) ) {
 441                                 for(Options::OrderedSymbolsIterator it = _options.orderedSymbolsBegin(); it != _options.orderedSymbolsEnd(); ++it) {
 442                                         if ( (it->objectFileName == NULL) && (strcmp(it->symbolName, atom.name()) == 0) ) {
 443                                                 // found in order file, move to __data section
 444                                                 fs = getFinalSection(InternalState::FinalSection::_s_DATA_data);\
 445                                                 //fprintf(stderr, "moved %s to __data section\n", atom.name());
 446                                                 break;
 447                                         }
 448                                 }
 449                         }
 450                         break;
 451                 default:
 452                         break;
 453         }
 454
 455         //fprintf(stderr, "InternalState::doAtom(%p), name=%s, sect=%s, finalsect=%p\n", &atom, atom.name(), atom.section().sectionName(), fs);
 456 #ifndef NDEBUG
 457         validateFixups(atom);
 458 #endif
 459         fs->atoms.push_back(&atom);
 460         return fs;
 461 }
 462
 463 ld::Internal::FinalSection* InternalState::getFinalSection(const ld::Section& inputSection)
 464 {
 465         const ld::Section* baseForFinalSection = &inputSection;
 466
 467         // see if input section already has a FinalSection
 468         SectionInToOut::iterator pos = _sectionInToFinalMap.find(&inputSection);
 469         if ( pos != _sectionInToFinalMap.end() ) {
 470                 return pos->second;
 471         }
 472
 473         // otherwise, create a new final section
 474         bool objFile = false;
 475         switch ( _options.outputKind() ) {
 476                 case Options::kStaticExecutable:
 477                 case Options::kDynamicExecutable:
 478                 case Options::kDynamicLibrary:
 479                 case Options::kDynamicBundle:
 480                 case Options::kDyld:
 481                 case Options::kKextBundle:
 482                 case Options::kPreload:
 483                         {
 484                                 // coalesce some sections
 485                                 const ld::Section& outSect = FinalSection::outputSection(inputSection);
 486                                 pos = _sectionInToFinalMap.find(&outSect);
 487                                 if ( pos != _sectionInToFinalMap.end() ) {
 488                                         _sectionInToFinalMap[&inputSection] = pos->second;
 489                                         //fprintf(stderr, "_sectionInToFinalMap[%p] = %p\n", &inputSection, pos->second);
 490                                         return pos->second;
 491                                 }
 492                                 else if ( outSect != inputSection ) {
 493                                         // new output section created, but not in map
 494                                         baseForFinalSection = &outSect;
 495                                 }
 496                         }
 497                         break;
 498                 case Options::kObjectFile:
 499                         baseForFinalSection = &FinalSection::objectOutputSection(inputSection, _options.makeTentativeDefinitionsReal());
 500                         pos = _sectionInToFinalMap.find(baseForFinalSection);
 501                         if ( pos != _sectionInToFinalMap.end() ) {
 502                                 _sectionInToFinalMap[&inputSection] = pos->second;
 503                                 //fprintf(stderr, "_sectionInToFinalMap[%p] = %p\n", &inputSection, pos->second);
 504                                 return pos->second;
 505                         }
 506                         objFile = true;
 507                         break;
 508         }
 509
 510         InternalState::FinalSection* result = new InternalState::FinalSection(*baseForFinalSection,
 511                                                                                                                                         _sectionInToFinalMap.size(), objFile);
 512         _sectionInToFinalMap[baseForFinalSection] = result;
 513         //fprintf(stderr, "_sectionInToFinalMap[%p] = %p\n", baseForFinalSection, result);
 514         sections.push_back(result);
 515         return result;
 516 }
 517
 518
 519 int InternalState::FinalSection::sectionComparer(const void* l, const void* r)
 520 {
 521         const FinalSection* left  = *(FinalSection**)l;
 522         const FinalSection* right = *(FinalSection**)r;
 523         if ( left->_segmentOrder != right->_segmentOrder )
 524                 return (left->_segmentOrder - right->_segmentOrder);
 525         return (left->_sectionOrder - right->_sectionOrder);
 526 }
 527
 528 void InternalState::sortSections()
 529 {
 530         //fprintf(stderr, "UNSORTED final sections:\n");
 531         //for (std::vector<ld::Internal::FinalSection*>::iterator it = sections.begin(); it != sections.end(); ++it) {
 532         //      fprintf(stderr, "final section %p %s/%s\n", (*it), (*it)->segmentName(), (*it)->sectionName());
 533         //}
 534         qsort(&sections[0], sections.size(), sizeof(FinalSection*), &InternalState::FinalSection::sectionComparer);
 535         //fprintf(stderr, "SORTED final sections:\n");
 536         //for (std::vector<ld::Internal::FinalSection*>::iterator it = sections.begin(); it != sections.end(); ++it) {
 537         //      fprintf(stderr, "final section %p %s/%s\n", (*it), (*it)->segmentName(), (*it)->sectionName());
 538         //}
 539         assert((sections[0]->type() == ld::Section::typeMachHeader)
 540                 || ((sections[0]->type() == ld::Section::typeFirstSection) && (sections[1]->type() == ld::Section::typeMachHeader))
 541                 || ((sections[0]->type() == ld::Section::typePageZero) && (sections[1]->type() == ld::Section::typeMachHeader))
 542                 || ((sections[0]->type() == ld::Section::typePageZero) && (sections[1]->type() == ld::Section::typeFirstSection) && (sections[2]->type() == ld::Section::typeMachHeader)) );
 543
 544 }
 545
 546 static void getVMInfo(vm_statistics_data_t& info)
 547 {
 548         mach_msg_type_number_t count = sizeof(vm_statistics_data_t) / sizeof(natural_t);
 549         kern_return_t error = host_statistics(mach_host_self(), HOST_VM_INFO,
 550                                                         (host_info_t)&info, &count);
 551         if (error != KERN_SUCCESS) {
 552                 bzero(&info, sizeof(vm_statistics_data_t));
 553         }
 554 }
 555
 556 int main(int argc, const char* argv[])
 557 {
 558 #if DEBUG
 559         usleep(1000000);
 560 #endif
 561         const char* archName = NULL;
 562         bool showArch = false;
 563         bool archInferred = false;
 564         try {
 565                 vm_statistics_data_t vmStart;
 566                 vm_statistics_data_t vmEnd;
 567                 getVMInfo(vmStart);
 568
 569                 // create object to track command line arguments
 570                 Options options(argc, argv);
 571
 572                 // gather stats
 573                 if ( options.printStatistics() )
 574                         getVMInfo(vmStart);
 575
 576                 // update strings for error messages
 577                 showArch = options.printArchPrefix();
 578                 archName = options.architectureName();
 579                 archInferred = (options.architecture() == 0);
 580
 581                 // open and parse input files
 582                 ld::tool::InputFiles inputFiles(options, &archName);
 583
 584                 // load and resolve all references
 585                 InternalState state(options);
 586                 ld::tool::Resolver resolver(options, inputFiles, state);
 587                 resolver.resolve();
 588
 589                 // add dylibs used
 590                 inputFiles.dylibs(state);
 591
 592                 // do initial section sorting so passes have rough idea of the layout
 593                 state.sortSections();
 594
 595                 // run passes
 596                 ld::passes::objc::doPass(options, state);
 597                 ld::passes::stubs::doPass(options, state);
 598                 ld::passes::huge::doPass(options, state);
 599                 ld::passes::got::doPass(options, state);
 600                 ld::passes::tlvp::doPass(options, state);
 601                 ld::passes::dylibs::doPass(options, state);     // must be after stubs and GOT passes
 602                 ld::passes::order_file::doPass(options, state);
 603                 ld::passes::branch_shim::doPass(options, state);        // must be after stubs
 604                 ld::passes::branch_island::doPass(options, state);      // must be after stubs and order_file pass
 605                 ld::passes::dtrace::doPass(options, state);
 606                 ld::passes::compact_unwind::doPass(options, state);  // must be after order-file pass
 607
 608                 // sort final sections
 609                 state.sortSections();
 610
 611                 // write output file
 612                 ld::tool::OutputFile out(options);
 613                 out.write(state);
 614
 615                 // print statistics
 616                 //mach_o::relocatable::printCounts();
 617                 if ( options.printStatistics() ) {
 618                         getVMInfo(vmEnd);
 619                         fprintf(stderr, "pageins=%u, pageouts=%u, faults=%u\n", vmEnd.pageins-vmStart.pageins,
 620                                                                                 vmEnd.pageouts-vmStart.pageouts, vmEnd.faults-vmStart.faults);
 621
 622                 }
 623         }
 624         catch (const char* msg) {
 625                 if ( archInferred )
 626                         fprintf(stderr, "ld: %s for inferred architecture %s\n", msg, archName);
 627                 else if ( showArch )
 628                         fprintf(stderr, "ld: %s for architecture %s\n", msg, archName);
 629                 else
 630                         fprintf(stderr, "ld: %s\n", msg);
 631                 return 1;
 632         }
 633
 634         return 0;
 635 }
 636
 637
 638 #ifndef NDEBUG
 639 // implement assert() function to print out a backtrace before aborting
 640 void __assert_rtn(const char* func, const char* file, int line, const char* failedexpr)
 641 {
 642         fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n", failedexpr, func, file, line);
 643
 644         void* callStack[128];
 645         int depth = ::backtrace(callStack, 128);
 646         char* buffer = (char*)malloc(1024);
 647         for(int i=0; i < depth-1; ++i) {
 648                 Dl_info info;
 649                 dladdr(callStack[i], &info);
 650                 const char* symboName = info.dli_sname;
 651                 if ( (symboName != NULL) && (strncmp(symboName, "_Z", 2) == 0) ) {
 652                         size_t bufLen = 1024;
 653                         int result;
 654                         char* unmangled = abi::__cxa_demangle(symboName, buffer, &bufLen, &result);
 655                         if ( unmangled != NULL )
 656                                 symboName = unmangled;
 657                 }
 658                 long offset = (uintptr_t)callStack[i] - (uintptr_t)info.dli_saddr;
 659                 fprintf(stderr, "%d  %p  %s + %ld\n", i, callStack[i], symboName, offset);
 660         }
 661         exit(1);
 662 }
 663 #endif
 664
 665