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MachOBinder.hpp
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MachOBinder.hpp
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/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
*
* Copyright (c) 2006-2011 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#ifndef __MACHO_BINDER__
#define __MACHO_BINDER__
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <mach/mach.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <mach-o/loader.h>
#include <mach-o/fat.h>
#include <vector>
#include <set>
#include <ext/hash_map>
#include <ext/hash_set>
#include "MachOFileAbstraction.hpp"
#include "Architectures.hpp"
#include "MachOLayout.hpp"
#include "MachORebaser.hpp"
#include "MachOTrie.hpp"
#ifndef EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER
#define EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER 0x10
#endif
template <typename A>
class Binder : public Rebaser<A>
{
public:
struct CStringEquals {
bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
};
typedef __gnu_cxx::hash_map<const char*, class Binder<A>*, __gnu_cxx::hash<const char*>, CStringEquals> Map;
Binder(const MachOLayoutAbstraction&, uint64_t dyldBaseAddress);
virtual ~Binder() {}
const char* getDylibID() const;
void setDependentBinders(const Map& map);
void bind(std::vector<void*>&);
void optimize();
void addResolverClient(Binder<A>* clientDylib, const char* symbolName);
void addResolverLazyPointerMappedAddress(const char* symbolName,
typename A::P::uint_t lpVMAddr);
private:
typedef typename A::P P;
typedef typename A::P::E E;
typedef typename A::P::uint_t pint_t;
struct BinderAndReExportFlag { Binder<A>* binder; bool reExport; };
struct SymbolReExport { const char* exportName; int dylibOrdinal; const char* importName; };
typedef __gnu_cxx::hash_map<const char*, pint_t, __gnu_cxx::hash<const char*>, CStringEquals> NameToAddrMap;
typedef __gnu_cxx::hash_set<const char*, __gnu_cxx::hash<const char*>, CStringEquals> NameSet;
struct ClientAndSymbol { Binder<A>* client; const char* symbolName; };
struct SymbolAndLazyPointer { const char* symbolName; pint_t lpVMAddr; };
static bool isPublicLocation(const char* pth);
void doBindExternalRelocations();
void doBindIndirectSymbols();
void doSetUpDyldSection();
void doSetPreboundUndefines();
void hoistPrivateRexports();
int ordinalOfDependentBinder(Binder<A>* dep);
void doBindDyldInfo(std::vector<void*>& pointersInData);
void doBindDyldLazyInfo(std::vector<void*>& pointersInData);
void bindDyldInfoAt(uint8_t segmentIndex, uint64_t segmentOffset, uint8_t type,
int libraryOrdinal, int64_t addend,
const char* symbolName, bool lazyPointer, bool weakImport,
std::vector<void*>& pointersInData);
pint_t resolveUndefined(const macho_nlist<P>* undefinedSymbol);
bool findExportedSymbolAddress(const char* name, pint_t* result, Binder<A>** foundIn, bool* isResolverSymbol);
void bindStub(uint8_t elementSize, uint8_t* location, pint_t vmlocation, pint_t value);
const char* parentUmbrella();
pint_t runtimeAddressFromNList(const macho_nlist<P>* sym);
void optimizeStub(const char* symbolName, pint_t lpVMAddr);
void optimizeStub(uint8_t* stubMappedAddress, pint_t stubVMAddress, uint32_t stubSize, pint_t lpVMAddr);
pint_t findLazyPointerFor(const char* symbolName);
static uint8_t pointerRelocSize();
static uint8_t pointerRelocType();
std::vector<BinderAndReExportFlag> fDependentDylibs;
NameToAddrMap fHashTable;
NameSet fSymbolResolvers;
std::vector<SymbolReExport> fReExportedSymbols;
uint64_t fDyldBaseAddress;
const macho_nlist<P>* fSymbolTable;
const char* fStrings;
const macho_dysymtab_command<P>* fDynamicInfo;
const macho_segment_command<P>* fFristWritableSegment;
const macho_dylib_command<P>* fDylibID;
const macho_dylib_command<P>* fParentUmbrella;
const macho_dyld_info_command<P>* fDyldInfo;
bool fOriginallyPrebound;
bool fReExportedSymbolsResolved;
std::vector<ClientAndSymbol> fClientAndSymbols;
std::vector<SymbolAndLazyPointer> fSymbolAndLazyPointers;
};
template <>
uint32_t Binder<arm>::runtimeAddressFromNList(const macho_nlist<Pointer32<LittleEndian> >* sym)
{
if (sym->n_desc() & N_ARM_THUMB_DEF)
return sym->n_value() + 1;
else
return sym->n_value();
}
template <typename A>
typename A::P::uint_t Binder<A>::runtimeAddressFromNList(const macho_nlist<P>* sym)
{
return sym->n_value();
}
template <typename A>
Binder<A>::Binder(const MachOLayoutAbstraction& layout, uint64_t dyldBaseAddress)
: Rebaser<A>(layout), fDyldBaseAddress(dyldBaseAddress),
fSymbolTable(NULL), fStrings(NULL), fDynamicInfo(NULL),
fFristWritableSegment(NULL), fDylibID(NULL), fDyldInfo(NULL),
fParentUmbrella(NULL), fReExportedSymbolsResolved(false)
{
fOriginallyPrebound = ((this->fHeader->flags() & MH_PREBOUND) != 0);
// update header flags so the cache looks prebound split-seg (0x80000000 is in-shared-cache bit)
((macho_header<P>*)this->fHeader)->set_flags(this->fHeader->flags() | MH_PREBOUND | MH_SPLIT_SEGS | 0x80000000);
// calculate fDynamicInfo, fStrings, fSymbolTable
const macho_symtab_command<P>* symtab;
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)this->fHeader + sizeof(macho_header<P>));
const uint32_t cmd_count = this->fHeader->ncmds();
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
switch (cmd->cmd()) {
case LC_SYMTAB:
symtab = (macho_symtab_command<P>*)cmd;
fSymbolTable = (macho_nlist<P>*)(&this->fLinkEditBase[symtab->symoff()]);
fStrings = (const char*)&this->fLinkEditBase[symtab->stroff()];
break;
case LC_DYSYMTAB:
fDynamicInfo = (macho_dysymtab_command<P>*)cmd;
break;
case LC_ID_DYLIB:
((macho_dylib_command<P>*)cmd)->set_timestamp(0);
fDylibID = (macho_dylib_command<P>*)cmd;
break;
case LC_LOAD_DYLIB:
case LC_LOAD_WEAK_DYLIB:
case LC_REEXPORT_DYLIB:
case LC_LOAD_UPWARD_DYLIB:
((macho_dylib_command<P>*)cmd)->set_timestamp(0);
break;
case LC_SUB_FRAMEWORK:
fParentUmbrella = (macho_dylib_command<P>*)cmd;
break;
case LC_DYLD_INFO:
case LC_DYLD_INFO_ONLY:
fDyldInfo = (macho_dyld_info_command<P>*)cmd;
break;
case LC_RPATH:
throwf("dyld shared cache does not support LC_RPATH found in %s", layout.getFilePath());
break;
default:
if ( cmd->cmd() & LC_REQ_DYLD )
throwf("unknown required load command 0x%08X", cmd->cmd());
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
if ( fDynamicInfo == NULL )
throw "no LC_DYSYMTAB";
if ( fSymbolTable == NULL )
throw "no LC_SYMTAB";
// build hash table
// fprintf(stderr, "exports for %s\n", layout.getFilePath());
if ( fDyldInfo != NULL ) {
std::vector<mach_o::trie::Entry> exports;
const uint8_t* exportsStart = layout.getDyldInfoExports();
const uint8_t* exportsEnd = &exportsStart[fDyldInfo->export_size()];
mach_o::trie::parseTrie(exportsStart, exportsEnd, exports);
pint_t baseAddress = layout.getSegments()[0].newAddress();
for(std::vector<mach_o::trie::Entry>::iterator it = exports.begin(); it != exports.end(); ++it) {
if ( (it->flags & EXPORT_SYMBOL_FLAGS_KIND_MASK) == EXPORT_SYMBOL_FLAGS_KIND_REGULAR ) {
if ( (it->flags & EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER) ) {
fSymbolResolvers.insert(it->name);
}
if ( it->flags & EXPORT_SYMBOL_FLAGS_REEXPORT ) {
//fprintf(stderr, "found re-export %s in %s\n", sym.exportName, this->getDylibID());
SymbolReExport sym;
sym.exportName = it->name;
sym.dylibOrdinal = it->other;
sym.importName = it->importName;
if ( (sym.importName == NULL) || (sym.importName[0] == '\0') )
sym.importName = sym.exportName;
fReExportedSymbols.push_back(sym);
// fHashTable entry will be added in first call to findExportedSymbolAddress()
}
else {
fHashTable[it->name] = it->address + baseAddress;
}
}
else {
throwf("non-regular symbol binding not supported for %s in %s", it->name, layout.getFilePath());
}
//fprintf(stderr, "0x%08llX %s\n", it->address + baseAddress, it->name);
}
}
else {
if ( fDynamicInfo->tocoff() == 0 ) {
const macho_nlist<P>* start = &fSymbolTable[fDynamicInfo->iextdefsym()];
const macho_nlist<P>* end = &start[fDynamicInfo->nextdefsym()];
fHashTable.resize(fDynamicInfo->nextdefsym()); // set initial bucket count
for (const macho_nlist<P>* sym=start; sym < end; ++sym) {
const char* name = &fStrings[sym->n_strx()];
fHashTable[name] = runtimeAddressFromNList(sym);
//fprintf(stderr, " 0x%08llX %s\n", sym->n_value(), name);
}
}
else {
int32_t count = fDynamicInfo->ntoc();
fHashTable.resize(count); // set initial bucket count
const struct dylib_table_of_contents* toc = (dylib_table_of_contents*)&this->fLinkEditBase[fDynamicInfo->tocoff()];
for (int32_t i = 0; i < count; ++i) {
const uint32_t index = E::get32(toc[i].symbol_index);
const macho_nlist<P>* sym = &fSymbolTable[index];
const char* name = &fStrings[sym->n_strx()];
fHashTable[name] = runtimeAddressFromNList(sym);
//fprintf(stderr, "- 0x%08llX %s\n", sym->n_value(), name);
}
}
}
}
template <> uint8_t Binder<x86>::pointerRelocSize() { return 2; }
template <> uint8_t Binder<x86_64>::pointerRelocSize() { return 3; }
template <> uint8_t Binder<arm>::pointerRelocSize() { return 2; }
template <> uint8_t Binder<x86>::pointerRelocType() { return GENERIC_RELOC_VANILLA; }
template <> uint8_t Binder<x86_64>::pointerRelocType() { return X86_64_RELOC_UNSIGNED; }
template <> uint8_t Binder<arm>::pointerRelocType() { return ARM_RELOC_VANILLA; }
template <typename A>
const char* Binder<A>::getDylibID() const
{
if ( fDylibID != NULL )
return fDylibID->name();
else
return NULL;
}
template <typename A>
const char* Binder<A>::parentUmbrella()
{
if ( fParentUmbrella != NULL )
return fParentUmbrella->name();
else
return NULL;
}
template <typename A>
bool Binder<A>::isPublicLocation(const char* pth)
{
// /usr/lib is a public location
if ( (strncmp(pth, "/usr/lib/", 9) == 0) && (strchr(&pth[9], '/') == NULL) )
return true;
// /System/Library/Frameworks/ is a public location
if ( strncmp(pth, "/System/Library/Frameworks/", 27) == 0 ) {
const char* frameworkDot = strchr(&pth[27], '.');
// but only top level framework
// /System/Library/Frameworks/Foo.framework/Versions/A/Foo ==> true
// /System/Library/Frameworks/Foo.framework/Resources/libBar.dylib ==> false
// /System/Library/Frameworks/Foo.framework/Frameworks/Bar.framework/Bar ==> false
// /System/Library/Frameworks/Foo.framework/Frameworks/Xfoo.framework/XFoo ==> false
if ( frameworkDot != NULL ) {
int frameworkNameLen = frameworkDot - &pth[27];
if ( strncmp(&pth[strlen(pth)-frameworkNameLen-1], &pth[26], frameworkNameLen+1) == 0 )
return true;
}
}
return false;
}
template <typename A>
void Binder<A>::setDependentBinders(const Map& map)
{
// first pass to build vector of dylibs
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)this->fHeader + sizeof(macho_header<P>));
const uint32_t cmd_count = this->fHeader->ncmds();
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
switch (cmd->cmd()) {
case LC_LOAD_DYLIB:
case LC_LOAD_WEAK_DYLIB:
case LC_REEXPORT_DYLIB:
case LC_LOAD_UPWARD_DYLIB:
const char* path = ((struct macho_dylib_command<P>*)cmd)->name();
typename Map::const_iterator pos = map.find(path);
if ( pos != map.end() ) {
BinderAndReExportFlag entry;
entry.binder = pos->second;
entry.reExport = ( cmd->cmd() == LC_REEXPORT_DYLIB );
fDependentDylibs.push_back(entry);
}
else {
// the load command string does not match the install name of any loaded dylib
// this could happen if there was not a world build and some dylib changed its
// install path to be some symlinked path
// use realpath() and walk map looking for a realpath match
bool found = false;
char targetPath[PATH_MAX];
if ( realpath(path, targetPath) != NULL ) {
for(typename Map::const_iterator it=map.begin(); it != map.end(); ++it) {
char aPath[PATH_MAX];
if ( realpath(it->first, aPath) != NULL ) {
if ( strcmp(targetPath, aPath) == 0 ) {
BinderAndReExportFlag entry;
entry.binder = it->second;
entry.reExport = ( cmd->cmd() == LC_REEXPORT_DYLIB );
fDependentDylibs.push_back(entry);
found = true;
fprintf(stderr, "update_dyld_shared_cache: warning mismatched install path in %s for %s\n",
this->getDylibID(), path);
break;
}
}
}
}
if ( ! found ) {
if ( cmd->cmd() == LC_LOAD_WEAK_DYLIB ) {
BinderAndReExportFlag entry;
entry.binder = NULL;
entry.reExport = false;
fDependentDylibs.push_back(entry);
break;
}
else {
throwf("in %s can't find dylib %s", this->getDylibID(), path);
}
}
}
break;
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
// handle pre-10.5 re-exports
if ( (this->fHeader->flags() & MH_NO_REEXPORTED_DYLIBS) == 0 ) {
cmd = cmds;
// LC_SUB_LIBRARY means re-export one with matching leaf name
const char* dylibBaseName;
const char* frameworkLeafName;
for (uint32_t i = 0; i < cmd_count; ++i) {
switch ( cmd->cmd() ) {
case LC_SUB_LIBRARY:
dylibBaseName = ((macho_sub_library_command<P>*)cmd)->sub_library();
for (typename std::vector<BinderAndReExportFlag>::iterator it = fDependentDylibs.begin(); it != fDependentDylibs.end(); ++it) {
const char* dylibName = it->binder->getDylibID();
const char* lastSlash = strrchr(dylibName, '/');
const char* leafStart = &lastSlash[1];
if ( lastSlash == NULL )
leafStart = dylibName;
const char* firstDot = strchr(leafStart, '.');
int len = strlen(leafStart);
if ( firstDot != NULL )
len = firstDot - leafStart;
if ( strncmp(leafStart, dylibBaseName, len) == 0 )
it->reExport = true;
}
break;
case LC_SUB_UMBRELLA:
frameworkLeafName = ((macho_sub_umbrella_command<P>*)cmd)->sub_umbrella();
for (typename std::vector<BinderAndReExportFlag>::iterator it = fDependentDylibs.begin(); it != fDependentDylibs.end(); ++it) {
const char* dylibName = it->binder->getDylibID();
const char* lastSlash = strrchr(dylibName, '/');
if ( (lastSlash != NULL) && (strcmp(&lastSlash[1], frameworkLeafName) == 0) )
it->reExport = true;
}
break;
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
// ask dependents if they re-export through me
const char* thisName = this->getDylibID();
if ( thisName != NULL ) {
const char* thisLeafName = strrchr(thisName, '/');
if ( thisLeafName != NULL )
++thisLeafName;
for (typename std::vector<BinderAndReExportFlag>::iterator it = fDependentDylibs.begin(); it != fDependentDylibs.end(); ++it) {
if ( ! it->reExport ) {
const char* parentUmbrellaName = it->binder->parentUmbrella();
if ( parentUmbrellaName != NULL ) {
if ( strcmp(parentUmbrellaName, thisLeafName) == 0 )
it->reExport = true;
}
}
}
}
}
}
template <typename A>
int Binder<A>::ordinalOfDependentBinder(Binder<A>* dep)
{
for (int i=0; i < fDependentDylibs.size(); ++i) {
if ( fDependentDylibs[i].binder == dep )
return i+1;
}
throw "dependend dylib not found";
}
template <typename A>
void Binder<A>::hoistPrivateRexports()
{
std::vector<Binder<A>*> privateReExportedDylibs;
for (typename std::vector<BinderAndReExportFlag>::iterator it = fDependentDylibs.begin(); it != fDependentDylibs.end(); ++it) {
if ( it->reExport && ! isPublicLocation(it->binder->getDylibID()) )
privateReExportedDylibs.push_back(it->binder);
}
if ( privateReExportedDylibs.size() != 0 ) {
// parse export info into vector of exports
const uint8_t* exportsStart = this->fLayout.getDyldInfoExports();
const uint8_t* exportsEnd = &exportsStart[fDyldInfo->export_size()];
std::vector<mach_o::trie::Entry> exports;
mach_o::trie::parseTrie(exportsStart, exportsEnd, exports);
//fprintf(stderr, "%s exports %lu symbols from trie of size %u \n", this->fLayout.getFilePath(), exports.size(), fDyldInfo->export_size());
// add re-exports for each export from an re-exported dylib
for(typename std::vector<Binder<A>*>::iterator it = privateReExportedDylibs.begin(); it != privateReExportedDylibs.end(); ++it) {
Binder<A>* binder = *it;
int ordinal = ordinalOfDependentBinder(binder);
const uint8_t* aDylibsExportsStart = binder->fLayout.getDyldInfoExports();
const uint8_t* aDylibsExportsEnd = &aDylibsExportsStart[binder->fDyldInfo->export_size()];
std::vector<mach_o::trie::Entry> aDylibsExports;
mach_o::trie::parseTrie(aDylibsExportsStart, aDylibsExportsEnd, aDylibsExports);
//fprintf(stderr, "%s re-exports %lu symbols from %s\n", this->fLayout.getFilePath(), aDylibsExports.size(), binder->getDylibID());
for(std::vector<mach_o::trie::Entry>::iterator eit = aDylibsExports.begin(); eit != aDylibsExports.end(); ++eit) {
mach_o::trie::Entry entry = *eit;
entry.flags |= EXPORT_SYMBOL_FLAGS_REEXPORT;
entry.other = ordinal;
entry.importName = NULL;
exports.push_back(entry);
}
}
// rebuild new combined trie
std::vector<uint8_t> newExportTrieBytes;
newExportTrieBytes.reserve(fDyldInfo->export_size());
mach_o::trie::makeTrie(exports, newExportTrieBytes);
//fprintf(stderr, "%s now exports %lu symbols from trie of size %lu\n", this->fLayout.getFilePath(), exports.size(), newExportTrieBytes.size());
// allocate new buffer and set export_off to use new buffer instead
uint32_t newExportsSize = newExportTrieBytes.size();
uint8_t* sideTrie = new uint8_t[newExportsSize];
memcpy(sideTrie, &newExportTrieBytes[0], newExportsSize);
this->fLayout.setDyldInfoExports(sideTrie);
((macho_dyld_info_command<P>*)fDyldInfo)->set_export_off(0); // invalidate old trie
((macho_dyld_info_command<P>*)fDyldInfo)->set_export_size(newExportsSize);
}
}
template <typename A>
void Binder<A>::bind(std::vector<void*>& pointersInData)
{
this->doSetUpDyldSection();
if ( fDyldInfo != NULL ) {
this->doBindDyldInfo(pointersInData);
this->doBindDyldLazyInfo(pointersInData);
this->hoistPrivateRexports();
// weak bind info is processed at launch time
}
else {
this->doBindExternalRelocations();
this->doBindIndirectSymbols();
this->doSetPreboundUndefines();
}
}
template <typename A>
void Binder<A>::doSetUpDyldSection()
{
// find __DATA __dyld section
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)this->fHeader + sizeof(macho_header<P>));
const uint32_t cmd_count = this->fHeader->ncmds();
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
const macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
if ( strcmp(seg->segname(), "__DATA") == 0 ) {
const macho_section<P>* const sectionsStart = (macho_section<P>*)((uint8_t*)seg + sizeof(macho_segment_command<P>));
const macho_section<P>* const sectionsEnd = §ionsStart[seg->nsects()];
for (const macho_section<P>* sect=sectionsStart; sect < sectionsEnd; ++sect) {
if ( (strcmp(sect->sectname(), "__dyld") == 0) && (sect->size() >= 2*sizeof(pint_t)) ) {
// set two values in __dyld section to point into dyld
pint_t* lazyBinder = this->mappedAddressForNewAddress(sect->addr());
pint_t* dyldFuncLookup = this->mappedAddressForNewAddress(sect->addr()+sizeof(pint_t));
A::P::setP(*lazyBinder, fDyldBaseAddress + 0x1000);
A::P::setP(*dyldFuncLookup, fDyldBaseAddress + 0x1008);
}
}
}
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
}
template <typename A>
void Binder<A>::bindDyldInfoAt(uint8_t segmentIndex, uint64_t segmentOffset, uint8_t type, int libraryOrdinal,
int64_t addend, const char* symbolName, bool lazyPointer, bool weakImport, std::vector<void*>& pointersInData)
{
//printf("%d 0x%08llX type=%d, lib=%d, addend=%lld, symbol=%s\n", segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName);
const std::vector<MachOLayoutAbstraction::Segment>& segments = this->fLayout.getSegments();
if ( segmentIndex > segments.size() )
throw "bad segment index in rebase info";
if ( libraryOrdinal == BIND_SPECIAL_DYLIB_FLAT_LOOKUP )
throw "dynamic lookup linkage not allowed in dyld shared cache";
if ( libraryOrdinal == BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE )
throw "linkage to main executable not allowed in dyld shared cache";
if ( libraryOrdinal < 0 )
throw "bad mach-o binary, special library ordinal not allowd in dyld shared cache";
if ( (unsigned)libraryOrdinal > fDependentDylibs.size() )
throw "bad mach-o binary, library ordinal too big";
Binder<A>* binder;
if ( libraryOrdinal == BIND_SPECIAL_DYLIB_SELF )
binder = this;
else
binder = fDependentDylibs[libraryOrdinal-1].binder;
pint_t targetSymbolAddress;
bool isResolverSymbol;
Binder<A>* foundIn;
if ( weakImport && (binder == NULL) ) {
targetSymbolAddress = 0;
foundIn = NULL;
isResolverSymbol = false;
}
else {
if ( ! binder->findExportedSymbolAddress(symbolName, &targetSymbolAddress, &foundIn, &isResolverSymbol) )
throwf("could not bind symbol %s in %s expected in %s", symbolName, this->getDylibID(), binder->getDylibID());
}
// don't bind lazy pointers to resolver stubs in shared cache
if ( lazyPointer && isResolverSymbol ) {
if ( foundIn == this ) {
// record location of lazy pointer for other dylibs to re-use
pint_t lpVMAddr = segments[segmentIndex].newAddress() + segmentOffset;
foundIn->addResolverLazyPointerMappedAddress(symbolName, lpVMAddr);
//fprintf(stderr, "resolver %s in %s has lazy pointer with segmentOffset=0x%08llX\n", symbolName, this->getDylibID(), segmentOffset);
}
else {
// record that this dylib has a lazy pointer to a resolver function
foundIn->addResolverClient(this, symbolName);
// fprintf(stderr, "have lazy pointer to resolver %s in %s\n", symbolName, this->getDylibID());
}
return;
}
// do actual update
const MachOLayoutAbstraction::Segment& seg = segments[segmentIndex];
uint8_t* mappedAddr = (uint8_t*)seg.mappedAddress() + segmentOffset;
pint_t* mappedAddrP = (pint_t*)mappedAddr;
uint32_t* mappedAddr32 = (uint32_t*)mappedAddr;
int32_t svalue32new;
switch ( type ) {
case BIND_TYPE_POINTER:
P::setP(*mappedAddrP, targetSymbolAddress + addend);
break;
case BIND_TYPE_TEXT_ABSOLUTE32:
E::set32(*mappedAddr32, targetSymbolAddress + addend);
break;
case BIND_TYPE_TEXT_PCREL32:
svalue32new = seg.address() + segmentOffset + 4 - (targetSymbolAddress + addend);
E::set32(*mappedAddr32, svalue32new);
break;
default:
throw "bad bind type";
}
pointersInData.push_back(mappedAddr);
}
template <typename A>
void Binder<A>::doBindDyldLazyInfo(std::vector<void*>& pointersInData)
{
const uint8_t* p = &this->fLinkEditBase[fDyldInfo->lazy_bind_off()];
const uint8_t* end = &p[fDyldInfo->lazy_bind_size()];
uint8_t type = BIND_TYPE_POINTER;
uint64_t segmentOffset = 0;
uint8_t segmentIndex = 0;
const char* symbolName = NULL;
int libraryOrdinal = 0;
int64_t addend = 0;
bool weakImport = false;
while ( p < end ) {
uint8_t immediate = *p & BIND_IMMEDIATE_MASK;
uint8_t opcode = *p & BIND_OPCODE_MASK;
++p;
switch (opcode) {
case BIND_OPCODE_DONE:
// this opcode marks the end of each lazy pointer binding
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_IMM:
libraryOrdinal = immediate;
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
libraryOrdinal = read_uleb128(p, end);
break;
case BIND_OPCODE_SET_DYLIB_SPECIAL_IMM:
// the special ordinals are negative numbers
if ( immediate == 0 )
libraryOrdinal = 0;
else {
int8_t signExtended = BIND_OPCODE_MASK | immediate;
libraryOrdinal = signExtended;
}
break;
case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
weakImport = ( (immediate & BIND_SYMBOL_FLAGS_WEAK_IMPORT) != 0 );
symbolName = (char*)p;
while (*p != '\0')
++p;
++p;
break;
case BIND_OPCODE_SET_ADDEND_SLEB:
addend = read_sleb128(p, end);
break;
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
segmentIndex = immediate;
segmentOffset = read_uleb128(p, end);
break;
case BIND_OPCODE_DO_BIND:
bindDyldInfoAt(segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName, true, weakImport, pointersInData);
segmentOffset += sizeof(pint_t);
break;
case BIND_OPCODE_SET_TYPE_IMM:
case BIND_OPCODE_ADD_ADDR_ULEB:
case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
default:
throwf("bad lazy bind opcode %d", *p);
}
}
}
template <typename A>
void Binder<A>::doBindDyldInfo(std::vector<void*>& pointersInData)
{
const uint8_t* p = &this->fLinkEditBase[fDyldInfo->bind_off()];
const uint8_t* end = &p[fDyldInfo->bind_size()];
uint8_t type = 0;
uint64_t segmentOffset = 0;
uint8_t segmentIndex = 0;
const char* symbolName = NULL;
int libraryOrdinal = 0;
int64_t addend = 0;
uint32_t count;
uint32_t skip;
bool weakImport = false;
bool done = false;
while ( !done && (p < end) ) {
uint8_t immediate = *p & BIND_IMMEDIATE_MASK;
uint8_t opcode = *p & BIND_OPCODE_MASK;
++p;
switch (opcode) {
case BIND_OPCODE_DONE:
done = true;
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_IMM:
libraryOrdinal = immediate;
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
libraryOrdinal = read_uleb128(p, end);
break;
case BIND_OPCODE_SET_DYLIB_SPECIAL_IMM:
// the special ordinals are negative numbers
if ( immediate == 0 )
libraryOrdinal = 0;
else {
int8_t signExtended = BIND_OPCODE_MASK | immediate;
libraryOrdinal = signExtended;
}
break;
case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
weakImport = ( (immediate & BIND_SYMBOL_FLAGS_WEAK_IMPORT) != 0 );
symbolName = (char*)p;
while (*p != '\0')
++p;
++p;
break;
case BIND_OPCODE_SET_TYPE_IMM:
type = immediate;
break;
case BIND_OPCODE_SET_ADDEND_SLEB:
addend = read_sleb128(p, end);
break;
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
segmentIndex = immediate;
segmentOffset = read_uleb128(p, end);
break;
case BIND_OPCODE_ADD_ADDR_ULEB:
segmentOffset += read_uleb128(p, end);
break;
case BIND_OPCODE_DO_BIND:
bindDyldInfoAt(segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName, false, weakImport, pointersInData);
segmentOffset += sizeof(pint_t);
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
bindDyldInfoAt(segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName, false, weakImport, pointersInData);
segmentOffset += read_uleb128(p, end) + sizeof(pint_t);
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
bindDyldInfoAt(segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName, false, weakImport, pointersInData);
segmentOffset += immediate*sizeof(pint_t) + sizeof(pint_t);
break;
case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
count = read_uleb128(p, end);
skip = read_uleb128(p, end);
for (uint32_t i=0; i < count; ++i) {
bindDyldInfoAt(segmentIndex, segmentOffset, type, libraryOrdinal, addend, symbolName, false, weakImport, pointersInData);
segmentOffset += skip + sizeof(pint_t);
}
break;
default:
throwf("bad bind opcode %d", *p);
}
}
}
template <typename A>
void Binder<A>::doSetPreboundUndefines()
{
const macho_dysymtab_command<P>* dysymtab = NULL;
macho_nlist<P>* symbolTable = NULL;
// get symbol table info
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)this->fHeader + sizeof(macho_header<P>));
const uint32_t cmd_count = this->fHeader->ncmds();
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
switch (cmd->cmd()) {
case LC_SYMTAB:
{
const macho_symtab_command<P>* symtab = (macho_symtab_command<P>*)cmd;
symbolTable = (macho_nlist<P>*)(&this->fLinkEditBase[symtab->symoff()]);
}
break;
case LC_DYSYMTAB:
dysymtab = (macho_dysymtab_command<P>*)cmd;
break;
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
// walk all undefines and set their prebound n_value
macho_nlist<P>* const lastUndefine = &symbolTable[dysymtab->iundefsym()+dysymtab->nundefsym()];
for (macho_nlist<P>* entry = &symbolTable[dysymtab->iundefsym()]; entry < lastUndefine; ++entry) {
if ( entry->n_type() & N_EXT ) {
//fprintf(stderr, "doSetPreboundUndefines: r_sym=%s, pbaddr=0x%08X, in %s\n",
// &fStrings[entry->n_strx()], pbaddr, this->getDylibID());
pint_t pbaddr = this->resolveUndefined(entry);
entry->set_n_value(pbaddr);
}
}
}
template <typename A>
void Binder<A>::doBindExternalRelocations()
{
// get where reloc addresses start
// these address are always relative to first writable segment because they are in cache which always
// has writable segments far from read-only segments
pint_t firstWritableSegmentBaseAddress = 0;
const std::vector<MachOLayoutAbstraction::Segment>& segments = this->fLayout.getSegments();
for(std::vector<MachOLayoutAbstraction::Segment>::const_iterator it = segments.begin(); it != segments.end(); ++it) {
const MachOLayoutAbstraction::Segment& seg = *it;
if ( seg.writable() ) {
firstWritableSegmentBaseAddress = seg.newAddress();
break;
}
}
// loop through all external relocation records and bind each
const macho_relocation_info<P>* const relocsStart = (macho_relocation_info<P>*)(&this->fLinkEditBase[fDynamicInfo->extreloff()]);
const macho_relocation_info<P>* const relocsEnd = &relocsStart[fDynamicInfo->nextrel()];
for (const macho_relocation_info<P>* reloc=relocsStart; reloc < relocsEnd; ++reloc) {
if ( reloc->r_length() != pointerRelocSize() )
throw "bad external relocation length";
if ( reloc->r_type() != pointerRelocType() )
throw "unknown external relocation type";
if ( reloc->r_pcrel() )
throw "r_pcrel external relocaiton not supported";
const macho_nlist<P>* undefinedSymbol = &fSymbolTable[reloc->r_symbolnum()];
pint_t* location;
try {
location = this->mappedAddressForNewAddress(reloc->r_address() + firstWritableSegmentBaseAddress);
}
catch (const char* msg) {
throwf("%s processesing external relocation r_address 0x%08X", msg, reloc->r_address());
}
pint_t addend = P::getP(*location);
if ( fOriginallyPrebound ) {
// in a prebound binary, the n_value field of an undefined symbol is set to the address where the symbol was found when prebound
// so, subtracting that gives the initial displacement which we need to add to the newly found symbol address
// if mach-o relocation structs had an "addend" field this complication would not be necessary.
addend -= undefinedSymbol->n_value();
// To further complicate things, if this is defined symbol, then its n_value has already been adjust to the
// new base address, so we need to back off the slide too..
if ( (undefinedSymbol->n_type() & N_TYPE) == N_SECT ) {
addend += this->getSlideForNewAddress(undefinedSymbol->n_value());
}
}
pint_t symbolAddr = this->resolveUndefined(undefinedSymbol);
//fprintf(stderr, "external reloc: r_address=0x%08X, r_sym=%s, symAddr=0x%08llX, addend=0x%08llX in %s\n",
// reloc->r_address(), &fStrings[undefinedSymbol->n_strx()], (uint64_t)symbolAddr, (uint64_t)addend, this->getDylibID());
P::setP(*location, symbolAddr + addend);
}
}
// most architectures use pure code, unmodifiable stubs
template <typename A>
void Binder<A>::bindStub(uint8_t elementSize, uint8_t* location, pint_t vmlocation, pint_t value)
{
// do nothing
}
// x86 supports fast stubs
template <>
void Binder<x86>::bindStub(uint8_t elementSize, uint8_t* location, pint_t vmlocation, pint_t value)
{
// if the stub is not 5-bytes, it is an old slow stub
if ( elementSize == 5 ) {
uint32_t rel32 = value - (vmlocation + 5);
location[0] = 0xE9; // JMP rel32
location[1] = rel32 & 0xFF;
location[2] = (rel32 >> 8) & 0xFF;
location[3] = (rel32 >> 16) & 0xFF;
location[4] = (rel32 >> 24) & 0xFF;
}
}
template <typename A>
void Binder<A>::doBindIndirectSymbols()
{
const uint32_t* const indirectTable = (uint32_t*)&this->fLinkEditBase[fDynamicInfo->indirectsymoff()];
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)this->fHeader + sizeof(macho_header<P>));
const uint32_t cmd_count = this->fHeader->ncmds();
const macho_load_command<P>* cmd = cmds;
//fprintf(stderr, "doBindIndirectSymbols() %s\n", this->fLayout.getFilePath());
for (uint32_t i = 0; i < cmd_count; ++i) {
if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
const macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
const macho_section<P>* const sectionsStart = (macho_section<P>*)((uint8_t*)seg + sizeof(macho_segment_command<P>));
const macho_section<P>* const sectionsEnd = §ionsStart[seg->nsects()];
for (const macho_section<P>* sect=sectionsStart; sect < sectionsEnd; ++sect) {
uint8_t elementSize = 0;
uint8_t sectionType = sect->flags() & SECTION_TYPE;
switch ( sectionType ) {
case S_SYMBOL_STUBS:
elementSize = sect->reserved2();
break;
case S_NON_LAZY_SYMBOL_POINTERS:
case S_LAZY_SYMBOL_POINTERS:
elementSize = sizeof(pint_t);
break;
}
if ( elementSize != 0 ) {
uint32_t elementCount = sect->size() / elementSize;
const uint32_t indirectTableOffset = sect->reserved1();
uint8_t* location = NULL;
if ( sect->size() != 0 )
location = (uint8_t*)this->mappedAddressForNewAddress(sect->addr());
pint_t vmlocation = sect->addr();
for (uint32_t j=0; j < elementCount; ++j, location += elementSize, vmlocation += elementSize) {
uint32_t symbolIndex = E::get32(indirectTable[indirectTableOffset + j]);
switch ( symbolIndex ) {
case INDIRECT_SYMBOL_ABS:
case INDIRECT_SYMBOL_LOCAL:
break;
default:
const macho_nlist<P>* undefinedSymbol = &fSymbolTable[symbolIndex];
//fprintf(stderr, " sect=%s, index=%d, symbolIndex=%d, sym=%s\n", sect->sectname(), j, symbolIndex, &fStrings[undefinedSymbol->n_strx()]);
pint_t symbolAddr = this->resolveUndefined(undefinedSymbol);
switch ( sectionType ) {
case S_NON_LAZY_SYMBOL_POINTERS:
case S_LAZY_SYMBOL_POINTERS:
P::setP(*((pint_t*)location), symbolAddr);
break;
case S_SYMBOL_STUBS:
this->bindStub(elementSize, location, vmlocation, symbolAddr);
break;
}
break;
}
}
}
}
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
}
template <typename A>
typename A::P::uint_t Binder<A>::resolveUndefined(const macho_nlist<P>* undefinedSymbol)
{
if ( (undefinedSymbol->n_type() & N_TYPE) == N_SECT ) {
if ( (undefinedSymbol->n_type() & N_PEXT) != 0 ) {
// is a multi-module private_extern internal reference that the linker did not optimize away
return runtimeAddressFromNList(undefinedSymbol);
}
if ( (undefinedSymbol->n_desc() & N_WEAK_DEF) != 0 ) {
// is a weak definition, we should prebind to this one in the same linkage unit
return runtimeAddressFromNList(undefinedSymbol);
}
}
const char* symbolName = &fStrings[undefinedSymbol->n_strx()];
if ( (this->fHeader->flags() & MH_TWOLEVEL) == 0 ) {
// flat namespace binding
throw "flat namespace not supported";
}
else {
uint8_t ordinal = GET_LIBRARY_ORDINAL(undefinedSymbol->n_desc());
Binder<A>* binder = NULL;
switch ( ordinal ) {
case EXECUTABLE_ORDINAL:
case DYNAMIC_LOOKUP_ORDINAL:
throw "magic ordineal not supported";
case SELF_LIBRARY_ORDINAL:
binder = this;
break;
default:
if ( ordinal > fDependentDylibs.size() )
throw "two-level ordinal out of range";
binder = fDependentDylibs[ordinal-1].binder;
}
pint_t addr;
bool isResolver;
Binder<A>* foundIn;
if ( ! binder->findExportedSymbolAddress(symbolName, &addr, &foundIn, &isResolver) )
throwf("could not resolve undefined symbol %s in %s expected in %s", symbolName, this->getDylibID(), binder->getDylibID());
return addr;
}