src/ld/passes/dylibs.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 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,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  19  * Please see the License for the specific language governing rights and
  20  * limitations under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24
  25
  26 #include <stdint.h>
  27 #include <math.h>
  28 #include <unistd.h>
  29 #include <dlfcn.h>
  30 #include <mach/machine.h>
  31
  32 #include <vector>
  33
  34 #include "ld.hpp"
  35 #include "dylibs.h"
  36
  37 namespace ld {
  38 namespace passes {
  39 namespace dylibs {
  40
  41
  42 class WillBeUsed
  43 {
  44 public:
  45         bool operator()(ld::dylib::File* dylib) const {
  46                 return dylib->willRemoved();
  47         }
  48 };
  49
  50
  51 void doPass(const Options& opts, ld::Internal& state)
  52 {
  53 //      const bool log = false;
  54
  55         // clear "willRemoved" bit on all dylibs
  56         for (std::vector<ld::dylib::File*>::iterator it = state.dylibs.begin(); it != state.dylibs.end(); ++it) {
  57                 ld::dylib::File* aDylib = *it;
  58                 aDylib->setWillBeRemoved(false);
  59         }
  60         for (std::vector<ld::dylib::File*>::iterator it = state.dylibs.begin(); it != state.dylibs.end(); ++it) {
  61                 ld::dylib::File* aDylib = *it;
  62                 // set "willRemoved" bit on implicit dylibs that did not provide any exports
  63                 if ( aDylib->implicitlyLinked() && !aDylib->explicitlyLinked() && !aDylib->providedExportAtom() )
  64                         aDylib->setWillBeRemoved(true);
  65                 // set "willRemoved" bit on dead strippable explicit dylibs that did not provide any exports
  66                 if ( aDylib->explicitlyLinked() && aDylib->deadStrippable() && !aDylib->providedExportAtom() )
  67                         aDylib->setWillBeRemoved(true);
  68                 // set "willRemoved" bit on any unused explicit when -dead_strip_dylibs is used
  69                 if ( opts.deadStripDylibs() && !aDylib->providedExportAtom() )
  70                         aDylib->setWillBeRemoved(true);
  71         }
  72         // remove unused dylibs
  73         state.dylibs.erase(std::remove_if(state.dylibs.begin(), state.dylibs.end(), WillBeUsed()), state.dylibs.end());
  74
  75
  76         // <rdar://problem/9441273> automatically weak-import dylibs when all symbols from it are weak-imported
  77         for (std::vector<ld::Internal::FinalSection*>::iterator sit=state.sections.begin(); sit != state.sections.end(); ++sit) {
  78                 ld::Internal::FinalSection* sect = *sit;
  79                 for (std::vector<const ld::Atom*>::iterator ait=sect->atoms.begin();  ait != sect->atoms.end(); ++ait) {
  80                         const ld::Atom* atom = *ait;
  81                         const ld::Atom* target = NULL;
  82                         bool targetIsWeakImport = false;
  83                         for (ld::Fixup::iterator fit = atom->fixupsBegin(), end=atom->fixupsEnd(); fit != end; ++fit) {
  84                                 if ( fit->firstInCluster() )
  85                                         target = NULL;
  86                                 switch ( fit->binding ) {
  87                                         case ld::Fixup::bindingsIndirectlyBound:
  88                                                 target = state.indirectBindingTable[fit->u.bindingIndex];
  89                                                 targetIsWeakImport = fit->weakImport;
  90                                                 break;
  91                                         case ld::Fixup::bindingDirectlyBound:
  92                                                 target = fit->u.target;
  93                                                 targetIsWeakImport = fit->weakImport;
  94                                                 break;
  95                     default:
  96                         break;
  97                                 }
  98                                 if ( (target != NULL) && (target->definition() == ld::Atom::definitionProxy) ) {
  99                                         ld::Atom::WeakImportState curWI = target->weakImportState();
 100                                         if ( curWI == ld::Atom::weakImportUnset ) {
 101                                                 // first use of this proxy, set weak-import based on this usage
 102                                                 (const_cast<ld::Atom*>(target))->setWeakImportState(targetIsWeakImport);
 103                                         }
 104                                         else {
 105                                                 // proxy already has weak-importness set, check for weakness mismatch
 106                                                 bool curIsWeakImport = (curWI == ld::Atom::weakImportTrue);
 107                                                 if ( curIsWeakImport != targetIsWeakImport ) {
 108                                                         // found mismatch
 109                                                         switch ( opts.weakReferenceMismatchTreatment() ) {
 110                                                                 case Options::kWeakReferenceMismatchError:
 111                                                                         throwf("mismatching weak references for symbol: %s", target->name());
 112                                                                 case Options::kWeakReferenceMismatchWeak:
 113                                                                         (const_cast<ld::Atom*>(target))->setWeakImportState(true);
 114                                                                         break;
 115                                                                 case Options::kWeakReferenceMismatchNonWeak:
 116                                                                         (const_cast<ld::Atom*>(target))->setWeakImportState(false);
 117                                                                         break;
 118                                                         }
 119                                                 }
 120                                         }
 121                                 }
 122                         }
 123                 }
 124         }
 125
 126 }
 127
 128
 129 } // namespace dylibs
 130 } // namespace passes
 131 } // namespace ld