dyld-851.27.tar.gz

[apple/dyld.git] / src / ImageLoaderMachOCompressed.cpp

/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
 *
 * Copyright (c) 2008 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@
 */


#if __arm__ || __arm64__
  #include <System/sys/mman.h>
#else
  #include <sys/mman.h>
#endif
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <sys/stat.h> 
#include <sys/param.h>
#include <mach/mach.h>
#include <mach/thread_status.h>
#include <mach-o/loader.h> 
#include <mach-o/dyld_images.h>

#include "dyld2.h"
#include "ImageLoaderMachOCompressed.h"
#include "Closure.h"
#include "Array.h"

#ifndef BIND_SUBOPCODE_THREADED_SET_JOP
   #define BIND_SUBOPCODE_THREADED_SET_JOP                                                              0x0F
#endif

// relocation_info.r_length field has value 3 for 64-bit executables and value 2 for 32-bit executables
#if __LP64__
        #define RELOC_SIZE 3
        #define LC_SEGMENT_COMMAND              LC_SEGMENT_64
        #define LC_ROUTINES_COMMAND             LC_ROUTINES_64
        struct macho_segment_command    : public segment_command_64  {};
        struct macho_section                    : public section_64  {};        
        struct macho_routines_command   : public routines_command_64  {};       
#else
        #define RELOC_SIZE 2
        #define LC_SEGMENT_COMMAND              LC_SEGMENT
        #define LC_ROUTINES_COMMAND             LC_ROUTINES
        struct macho_segment_command    : public segment_command {};
        struct macho_section                    : public section  {};   
        struct macho_routines_command   : public routines_command  {};  
#endif



// create image for main executable
ImageLoaderMachOCompressed* ImageLoaderMachOCompressed::instantiateMainExecutable(const macho_header* mh, uintptr_t slide, const char* path, 
                                                                                                                                                unsigned int segCount, unsigned int libCount, const LinkContext& context)
{
        ImageLoaderMachOCompressed* image = ImageLoaderMachOCompressed::instantiateStart(mh, path, segCount, libCount);

        // set slide for PIE programs
        image->setSlide(slide);

        // for PIE record end of program, to know where to start loading dylibs
        if ( slide != 0 )
                fgNextPIEDylibAddress = (uintptr_t)image->getEnd();

        image->disableCoverageCheck();
        image->instantiateFinish(context);
        image->setMapped(context);

        if ( context.verboseMapping ) {
                dyld::log("dyld: Main executable mapped %s\n", path);
                for(unsigned int i=0, e=image->segmentCount(); i < e; ++i) {
                        const char* name = image->segName(i);
                        if ( (strcmp(name, "__PAGEZERO") == 0) || (strcmp(name, "__UNIXSTACK") == 0)  )
                                dyld::log("%18s at 0x%08lX->0x%08lX\n", name, image->segPreferredLoadAddress(i), image->segPreferredLoadAddress(i)+image->segSize(i));
                        else
                                dyld::log("%18s at 0x%08lX->0x%08lX\n", name, image->segActualLoadAddress(i), image->segActualEndAddress(i));
                }
        }

        return image;
}

// create image by mapping in a mach-o file
ImageLoaderMachOCompressed* ImageLoaderMachOCompressed::instantiateFromFile(const char* path, int fd, const uint8_t* fileData, size_t lenFileData,
                                                                                                                        uint64_t offsetInFat, uint64_t lenInFat, const struct stat& info, 
                                                                                                                        unsigned int segCount, unsigned int libCount, 
                                                                                                                        const struct linkedit_data_command* codeSigCmd, 
                                                                                                                        const struct encryption_info_command* encryptCmd, 
                                                                                                                        const LinkContext& context)
{
        ImageLoaderMachOCompressed* image = ImageLoaderMachOCompressed::instantiateStart((macho_header*)fileData, path, segCount, libCount);

        try {
                // record info about file  
                image->setFileInfo(info.st_dev, info.st_ino, info.st_mtime);

                // if this image is code signed, let kernel validate signature before mapping any pages from image
                image->loadCodeSignature(codeSigCmd, fd, offsetInFat, context);
                
                // Validate that first data we read with pread actually matches with code signature
                image->validateFirstPages(codeSigCmd, fd, fileData, lenFileData, offsetInFat, context);

                // mmap segments
                image->mapSegments(fd, offsetInFat, lenInFat, info.st_size, context);

                // if framework is FairPlay encrypted, register with kernel
                image->registerEncryption(encryptCmd, context);
                
                // probe to see if code signed correctly
                image->crashIfInvalidCodeSignature();

                // finish construction
                image->instantiateFinish(context);
                
                // if path happens to be same as in LC_DYLIB_ID load command use that, otherwise malloc a copy of the path
                const char* installName = image->getInstallPath();
                if ( (installName != NULL) && (strcmp(installName, path) == 0) && (path[0] == '/') )
                        image->setPathUnowned(installName);
#if TARGET_OS_OSX
                // <rdar://problem/6563887> app crashes when libSystem cannot be found
                else if ( (installName != NULL) && (strcmp(path, "/usr/lib/libgcc_s.1.dylib") == 0) && (strcmp(installName, "/usr/lib/libSystem.B.dylib") == 0) )
                        image->setPathUnowned("/usr/lib/libSystem.B.dylib");
#endif
                else if ( (path[0] != '/') || (strstr(path, "../") != NULL) ) {
                        // rdar://problem/10733082 Fix up @rpath based paths during introspection
                        // rdar://problem/5135363 turn relative paths into absolute paths so gdb, Symbolication can later find them
                        char realPath[MAXPATHLEN];
                        if ( fcntl(fd, F_GETPATH, realPath) == 0 ) 
                                image->setPaths(path, realPath);
                        else
                                image->setPath(path);
                }
                else {
                        // <rdar://problem/46682306> always try to realpath dylibs since they may have been dlopen()ed using a symlink path
                        if ( installName != NULL ) {
                                char realPath[MAXPATHLEN];
                                if ( (fcntl(fd, F_GETPATH, realPath) == 0) && (strcmp(path, realPath) != 0) )
                                        image->setPaths(path, realPath);
                                else
                                        image->setPath(path);
                        }
                        else {
                                image->setPath(path);
                        }
                }

                // make sure path is stable before recording in dyld_all_image_infos
                image->setMapped(context);

        }
        catch (...) {
                // ImageLoader::setMapped() can throw an exception to block loading of image
                // <rdar://problem/6169686> Leaked fSegmentsArray and image segments during failed dlopen_preflight
                delete image;
                throw;
        }
        
        return image;
}

// create image by using cached mach-o file
ImageLoaderMachOCompressed* ImageLoaderMachOCompressed::instantiateFromCache(const macho_header* mh, const char* path, long slide,
                                                                                                                                                const struct stat& info, unsigned int segCount,
                                                                                                                                                unsigned int libCount, const LinkContext& context)
{
        ImageLoaderMachOCompressed* image = ImageLoaderMachOCompressed::instantiateStart(mh, path, segCount, libCount);
        try {
                // record info about file  
                image->setFileInfo(info.st_dev, info.st_ino, info.st_mtime);

                // remember this is from shared cache and cannot be unloaded
                image->fInSharedCache = true;
                image->setNeverUnload();
                image->setSlide(slide);
                image->disableCoverageCheck();

                // segments already mapped in cache
                if ( context.verboseMapping ) {
                        dyld::log("dyld: Using shared cached for %s\n", path);
                        for(unsigned int i=0; i < image->fSegmentsCount; ++i) {
                                dyld::log("%18s at 0x%08lX->0x%08lX\n", image->segName(i), image->segActualLoadAddress(i), image->segActualEndAddress(i));
                        }
                }

                image->instantiateFinish(context);
                
#if TARGET_OS_SIMULATOR
                char realPath[MAXPATHLEN] = { 0 };
                if ( dyld::gLinkContext.rootPaths == NULL )
                        throw "root path is not set";
                strlcpy(realPath, dyld::gLinkContext.rootPaths[0], MAXPATHLEN);
                strlcat(realPath, path, MAXPATHLEN);
                image->setPaths(path, realPath);
#endif
                image->setMapped(context);
        }
        catch (...) {
                // ImageLoader::setMapped() can throw an exception to block loading of image
                // <rdar://problem/6169686> Leaked fSegmentsArray and image segments during failed dlopen_preflight
                delete image;
                throw;
        }
        
        return image;
}

// create image by copying an in-memory mach-o file
ImageLoaderMachOCompressed* ImageLoaderMachOCompressed::instantiateFromMemory(const char* moduleName, const macho_header* mh, uint64_t len, 
                                                                                                                        unsigned int segCount, unsigned int libCount, const LinkContext& context)
{
        ImageLoaderMachOCompressed* image = ImageLoaderMachOCompressed::instantiateStart(mh, moduleName, segCount, libCount);
        try {
                // map segments 
                if ( mh->filetype == MH_EXECUTE ) 
                        throw "can't load another MH_EXECUTE";
                
                // vmcopy segments
                image->mapSegments((const void*)mh, len, context);
                
                // for compatibility, never unload dylibs loaded from memory
                image->setNeverUnload();

                image->disableCoverageCheck();

                // bundle loads need path copied
                if ( moduleName != NULL ) 
                        image->setPath(moduleName);

                image->instantiateFinish(context);
                image->setMapped(context);
        }
        catch (...) {
                // ImageLoader::setMapped() can throw an exception to block loading of image
                // <rdar://problem/6169686> Leaked fSegmentsArray and image segments during failed dlopen_preflight
                delete image;
                throw;
        }
        
        return image;
}


ImageLoaderMachOCompressed::ImageLoaderMachOCompressed(const macho_header* mh, const char* path, unsigned int segCount, 
                                                                                                                                                uint32_t segOffsets[], unsigned int libCount)
 : ImageLoaderMachO(mh, path, segCount, segOffsets, libCount), fDyldInfo(NULL), fChainedFixups(NULL), fExportsTrie(NULL)
{
}

ImageLoaderMachOCompressed::~ImageLoaderMachOCompressed()
{
        // don't do clean up in ~ImageLoaderMachO() because virtual call to segmentCommandOffsets() won't work
        destroy();
}



// construct ImageLoaderMachOCompressed using "placement new" with SegmentMachO objects array at end
ImageLoaderMachOCompressed* ImageLoaderMachOCompressed::instantiateStart(const macho_header* mh, const char* path, 
                                                                                                                                                        unsigned int segCount, unsigned int libCount)
{
        size_t size = sizeof(ImageLoaderMachOCompressed) + segCount * sizeof(uint32_t) + libCount * sizeof(ImageLoader*);
        ImageLoaderMachOCompressed* allocatedSpace = static_cast<ImageLoaderMachOCompressed*>(malloc(size));
        if ( allocatedSpace == NULL )
                throw "malloc failed";
        uint32_t* segOffsets = ((uint32_t*)(((uint8_t*)allocatedSpace) + sizeof(ImageLoaderMachOCompressed)));
        bzero(&segOffsets[segCount], libCount*sizeof(void*));   // zero out lib array
        return new (allocatedSpace) ImageLoaderMachOCompressed(mh, path, segCount, segOffsets, libCount);
}


// common code to finish initializing object
void ImageLoaderMachOCompressed::instantiateFinish(const LinkContext& context)
{
        // now that segments are mapped in, get real fMachOData, fLinkEditBase, and fSlide
        this->parseLoadCmds(context);
}

uint32_t* ImageLoaderMachOCompressed::segmentCommandOffsets() const
{
        return ((uint32_t*)(((uint8_t*)this) + sizeof(ImageLoaderMachOCompressed)));
}


ImageLoader* ImageLoaderMachOCompressed::libImage(unsigned int libIndex) const
{
        const uintptr_t* images = ((uintptr_t*)(((uint8_t*)this) + sizeof(ImageLoaderMachOCompressed) + fSegmentsCount*sizeof(uint32_t)));
        // mask off low bits
        return (ImageLoader*)(images[libIndex] & (-4));
}

bool ImageLoaderMachOCompressed::libReExported(unsigned int libIndex) const
{
        const uintptr_t* images = ((uintptr_t*)(((uint8_t*)this) + sizeof(ImageLoaderMachOCompressed) + fSegmentsCount*sizeof(uint32_t)));
        // re-export flag is low bit
        return ((images[libIndex] & 1) != 0);
}       

bool ImageLoaderMachOCompressed::libIsUpward(unsigned int libIndex) const
{
        const uintptr_t* images = ((uintptr_t*)(((uint8_t*)this) + sizeof(ImageLoaderMachOCompressed) + fSegmentsCount*sizeof(uint32_t)));
        // upward flag is second bit
        return ((images[libIndex] & 2) != 0);
}       


void ImageLoaderMachOCompressed::setLibImage(unsigned int libIndex, ImageLoader* image, bool reExported, bool upward)
{
        uintptr_t* images = ((uintptr_t*)(((uint8_t*)this) + sizeof(ImageLoaderMachOCompressed) + fSegmentsCount*sizeof(uint32_t)));
        uintptr_t value = (uintptr_t)image;
        if ( reExported ) 
                value |= 1;
        if ( upward ) 
                value |= 2;
        images[libIndex] = value;
}


void ImageLoaderMachOCompressed::rebaseAt(const LinkContext& context, uintptr_t addr, uintptr_t slide, uint8_t type)
{
        if ( context.verboseRebase ) {
                dyld::log("dyld: rebase: %s:*0x%08lX += 0x%08lX\n", this->getShortName(), (uintptr_t)addr, slide);
        }
        //dyld::log("0x%08lX type=%d\n", addr, type);
        uintptr_t* locationToFix = (uintptr_t*)addr;
        switch (type) {
                case REBASE_TYPE_POINTER:
                        *locationToFix += slide;
                        break;
                case REBASE_TYPE_TEXT_ABSOLUTE32:
                        *locationToFix += slide;
                        break;
                default:
                        dyld::throwf("bad rebase type %d", type);
        }
}

void ImageLoaderMachOCompressed::throwBadRebaseAddress(uintptr_t address, uintptr_t segmentEndAddress, int segmentIndex, 
                                                                                const uint8_t* startOpcodes, const uint8_t* endOpcodes, const uint8_t* pos)
{
        dyld::throwf("malformed rebase opcodes (%ld/%ld): address 0x%08lX is outside of segment %s (0x%08lX -> 0x%08lX)",
                (intptr_t)(pos-startOpcodes), (intptr_t)(endOpcodes-startOpcodes), address, segName(segmentIndex), 
                segActualLoadAddress(segmentIndex), segmentEndAddress); 
}

void ImageLoaderMachOCompressed::rebase(const LinkContext& context, uintptr_t slide)
{
        // binary uses chained fixups where are applied during binding
        if ( fDyldInfo == NULL )
                return;

        CRSetCrashLogMessage2(this->getPath());
        const uint8_t* const start = fLinkEditBase + fDyldInfo->rebase_off;
        const uint8_t* const end = &start[fDyldInfo->rebase_size];
        const uint8_t* p = start;

        if ( start == end )
                return;

        uint32_t ignore;
        bool bindingBecauseOfRoot = this->overridesCachedDylib(ignore);
        vmAccountingSetSuspended(context, bindingBecauseOfRoot);

        try {
                uint8_t type = 0;
                int segmentIndex = 0;
                uintptr_t address = segActualLoadAddress(0);
                uintptr_t segmentStartAddress = segActualLoadAddress(0);
                uintptr_t segmentEndAddress = segActualEndAddress(0);
                uintptr_t count;
                uintptr_t skip;
                bool done = false;
                while ( !done && (p < end) ) {
                        uint8_t immediate = *p & REBASE_IMMEDIATE_MASK;
                        uint8_t opcode = *p & REBASE_OPCODE_MASK;
                        ++p;
                        switch (opcode) {
                                case REBASE_OPCODE_DONE:
                                        done = true;
                                        break;
                                case REBASE_OPCODE_SET_TYPE_IMM:
                                        type = immediate;
                                        break;
                                case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
                                        segmentIndex = immediate;
                                        if ( segmentIndex >= fSegmentsCount )
                                                dyld::throwf("REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is too large (0..%d)",
                                                                segmentIndex, fSegmentsCount-1);
                        #if TEXT_RELOC_SUPPORT
                                        if ( !segWriteable(segmentIndex) && !segHasRebaseFixUps(segmentIndex) && !segHasBindFixUps(segmentIndex) )
                        #else
                                        if ( !segWriteable(segmentIndex) )
                        #endif
                                                dyld::throwf("REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is not a writable segment (%s)",
                                                                segmentIndex, segName(segmentIndex));
                                        segmentStartAddress = segActualLoadAddress(segmentIndex);
                                        segmentEndAddress = segActualEndAddress(segmentIndex);
                                        address = segmentStartAddress + read_uleb128(p, end);
                                        break;
                                case REBASE_OPCODE_ADD_ADDR_ULEB:
                                        address += read_uleb128(p, end);
                                        break;
                                case REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
                                        address += immediate*sizeof(uintptr_t);
                                        break;
                                case REBASE_OPCODE_DO_REBASE_IMM_TIMES:
                                        for (int i=0; i < immediate; ++i) {
                                                if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                        throwBadRebaseAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                                rebaseAt(context, address, slide, type);
                                                address += sizeof(uintptr_t);
                                        }
                                        fgTotalRebaseFixups += immediate;
                                        break;
                                case REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
                                        count = read_uleb128(p, end);
                                        for (uint32_t i=0; i < count; ++i) {
                                                if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                        throwBadRebaseAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                                rebaseAt(context, address, slide, type);
                                                address += sizeof(uintptr_t);
                                        }
                                        fgTotalRebaseFixups += count;
                                        break;
                                case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
                                        if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                throwBadRebaseAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                        rebaseAt(context, address, slide, type);
                                        address += read_uleb128(p, end) + sizeof(uintptr_t);
                                        ++fgTotalRebaseFixups;
                                        break;
                                case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
                                        count = read_uleb128(p, end);
                                        skip = read_uleb128(p, end);
                                        for (uint32_t i=0; i < count; ++i) {
                                                if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                        throwBadRebaseAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                                rebaseAt(context, address, slide, type);
                                                address += skip + sizeof(uintptr_t);
                                        }
                                        fgTotalRebaseFixups += count;
                                        break;
                                default:
                                        dyld::throwf("bad rebase opcode %d", *(p-1));
                        }
                }
        }
        catch (const char* msg) {
                const char* newMsg = dyld::mkstringf("%s in %s", msg, this->getPath());
                free((void*)msg);
                throw newMsg;
        }
        CRSetCrashLogMessage2(NULL);
}

const ImageLoader::Symbol* ImageLoaderMachOCompressed::findShallowExportedSymbol(const char* symbol, const ImageLoader** foundIn) const
{
        //dyld::log("Compressed::findExportedSymbol(%s) in %s\n", symbol, this->getShortName());
        uint32_t trieFileOffset = fDyldInfo ? fDyldInfo->export_off  : fExportsTrie->dataoff;
        uint32_t trieFileSize   = fDyldInfo ? fDyldInfo->export_size : fExportsTrie->datasize;
        if ( trieFileSize == 0 )
                return NULL;
#if LOG_BINDINGS
        dyld::logBindings("%s: %s\n", this->getShortName(), symbol);
#endif
        ++ImageLoaderMachO::fgSymbolTrieSearchs;
        const uint8_t* start = &fLinkEditBase[trieFileOffset];
        const uint8_t* end = &start[trieFileSize];
        const uint8_t* foundNodeStart = this->trieWalk(start, end, symbol); 
        if ( foundNodeStart != NULL ) {
                const uint8_t* p = foundNodeStart;
                const uintptr_t flags = read_uleb128(p, end);
                // found match, return pointer to terminal part of node
                if ( flags & EXPORT_SYMBOL_FLAGS_REEXPORT ) {
                        // re-export from another dylib, lookup there
                        const uintptr_t ordinal = read_uleb128(p, end);
                        const char* importedName = (char*)p;
                        if ( importedName[0] == '\0' )
                                importedName = symbol;
                        if ( (ordinal > 0) && (ordinal <= libraryCount()) ) {
                                const ImageLoader* reexportedFrom = libImage((unsigned int)ordinal-1);
                                // Missing weak-dylib
                                if ( reexportedFrom == NULL )
                                        return NULL;
                                //dyld::log("Compressed::findExportedSymbol(), %s -> %s/%s\n", symbol, reexportedFrom->getShortName(), importedName);
                                const char* reExportLibPath = libPath((unsigned int)ordinal-1);
                                return reexportedFrom->findExportedSymbol(importedName, true, reExportLibPath, foundIn);
                        }
                        else {
                                //dyld::throwf("bad mach-o binary, library ordinal (%u) invalid (max %u) for re-exported symbol %s in %s",
                                //      ordinal, libraryCount(), symbol, this->getPath());
                        }
                }
                else {
                        //dyld::log("findExportedSymbol(%s) in %s found match, returning %p\n", symbol, this->getShortName(), p);
                        if ( foundIn != NULL )
                                *foundIn = (ImageLoader*)this;          
                        // return pointer to terminal part of node
                        return (Symbol*)foundNodeStart;
                }
        }
        return NULL;
}


bool ImageLoaderMachOCompressed::containsSymbol(const void* addr) const
{
        uint32_t trieFileOffset = fDyldInfo ? fDyldInfo->export_off  : fExportsTrie->dataoff;
        uint32_t trieFileSize   = fDyldInfo ? fDyldInfo->export_size : fExportsTrie->datasize;
        const uint8_t* start = &fLinkEditBase[trieFileOffset];
        const uint8_t* end = &start[trieFileSize];
        return ( (start <= addr) && (addr < end) );
}


uintptr_t ImageLoaderMachOCompressed::exportedSymbolAddress(const LinkContext& context, const Symbol* symbol, const ImageLoader* requestor, bool runResolver) const
{
        uint32_t trieFileOffset = fDyldInfo ? fDyldInfo->export_off  : fExportsTrie->dataoff;
        uint32_t trieFileSize   = fDyldInfo ? fDyldInfo->export_size : fExportsTrie->datasize;
        const uint8_t* exportNode = (uint8_t*)symbol;
        const uint8_t* exportTrieStart = fLinkEditBase + trieFileOffset;
        const uint8_t* exportTrieEnd = exportTrieStart + trieFileSize;
        if ( (exportNode < exportTrieStart) || (exportNode > exportTrieEnd) )
                throw "symbol is not in trie";
        //dyld::log("exportedSymbolAddress(): node=%p, nodeOffset=0x%04X in %s\n", symbol, (int)((uint8_t*)symbol - exportTrieStart), this->getShortName());
        uintptr_t flags = read_uleb128(exportNode, exportTrieEnd);
        switch ( flags & EXPORT_SYMBOL_FLAGS_KIND_MASK ) {
                case EXPORT_SYMBOL_FLAGS_KIND_REGULAR:
                        if ( runResolver && (flags & EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER) ) {
                                // this node has a stub and resolver, run the resolver to get target address
                                uintptr_t stub = read_uleb128(exportNode, exportTrieEnd) + (uintptr_t)fMachOData; // skip over stub
                                // <rdar://problem/10657737> interposing dylibs have the stub address as their replacee
                                uintptr_t interposedStub = interposedAddress(context, stub, requestor);
                                if ( interposedStub != stub )
                                        return interposedStub;
                                // stub was not interposed, so run resolver
                                typedef uintptr_t (*ResolverProc)(void);
                                ResolverProc resolver = (ResolverProc)(read_uleb128(exportNode, exportTrieEnd) + (uintptr_t)fMachOData);
#if __has_feature(ptrauth_calls)
                                resolver = (ResolverProc)__builtin_ptrauth_sign_unauthenticated(resolver, ptrauth_key_asia, 0);
#endif
                                uintptr_t result = (*resolver)();
                                if ( context.verboseBind )
                                        dyld::log("dyld: resolver at %p returned 0x%08lX\n", resolver, result);
#if __has_feature(ptrauth_calls)
                        result = (uintptr_t)__builtin_ptrauth_strip((void*)result, ptrauth_key_asia);
#endif
                                return result;
                        }
                        return read_uleb128(exportNode, exportTrieEnd) + (uintptr_t)fMachOData;
                case EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL:
                        if ( flags & EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER )
                                dyld::throwf("unsupported exported symbol kind. flags=%lu at node=%p", flags, symbol);
                        return read_uleb128(exportNode, exportTrieEnd) + (uintptr_t)fMachOData;
                case EXPORT_SYMBOL_FLAGS_KIND_ABSOLUTE:
                        if ( flags & EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER )
                                dyld::throwf("unsupported exported symbol kind. flags=%lu at node=%p", flags, symbol);
                        return read_uleb128(exportNode, exportTrieEnd);
                default:
                        dyld::throwf("unsupported exported symbol kind. flags=%lu at node=%p", flags, symbol);
        }
}

bool ImageLoaderMachOCompressed::exportedSymbolIsWeakDefintion(const Symbol* symbol) const
{
        uint32_t trieFileOffset = fDyldInfo ? fDyldInfo->export_off  : fExportsTrie->dataoff;
        uint32_t trieFileSize   = fDyldInfo ? fDyldInfo->export_size : fExportsTrie->datasize;
        const uint8_t* exportNode = (uint8_t*)symbol;
        const uint8_t* exportTrieStart = fLinkEditBase + trieFileOffset;
        const uint8_t* exportTrieEnd = exportTrieStart + trieFileSize;
        if ( (exportNode < exportTrieStart) || (exportNode > exportTrieEnd) )
                throw "symbol is not in trie";
        uintptr_t flags = read_uleb128(exportNode, exportTrieEnd);
        return ( flags & EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION );
}


const char* ImageLoaderMachOCompressed::exportedSymbolName(const Symbol* symbol) const
{
        throw "NSNameOfSymbol() not supported with compressed LINKEDIT";
}

unsigned int ImageLoaderMachOCompressed::exportedSymbolCount() const
{
        throw "NSSymbolDefinitionCountInObjectFileImage() not supported with compressed LINKEDIT";
}

const ImageLoader::Symbol* ImageLoaderMachOCompressed::exportedSymbolIndexed(unsigned int index) const
{
        throw "NSSymbolDefinitionNameInObjectFileImage() not supported with compressed LINKEDIT";
}

unsigned int ImageLoaderMachOCompressed::importedSymbolCount() const
{
        throw "NSSymbolReferenceCountInObjectFileImage() not supported with compressed LINKEDIT";
}

const ImageLoader::Symbol* ImageLoaderMachOCompressed::importedSymbolIndexed(unsigned int index) const
{
        throw "NSSymbolReferenceCountInObjectFileImage() not supported with compressed LINKEDIT";
}

const char* ImageLoaderMachOCompressed::importedSymbolName(const Symbol* symbol) const
{
        throw "NSSymbolReferenceNameInObjectFileImage() not supported with compressed LINKEDIT";
}



uintptr_t ImageLoaderMachOCompressed::resolveFlat(const LinkContext& context, const char* symbolName, bool weak_import, 
                                                                                                        bool runResolver, const ImageLoader** foundIn)
{
        const Symbol* sym;
        if ( context.flatExportFinder(symbolName, &sym, foundIn) ) {
                if ( *foundIn != this )
                        context.addDynamicReference(this, const_cast<ImageLoader*>(*foundIn));
                return (*foundIn)->getExportedSymbolAddress(sym, context, this, runResolver);
        }
        // if a bundle is loaded privately the above will not find its exports
        if ( this->isBundle() && this->hasHiddenExports() ) {
                // look in self for needed symbol
                sym = this->findShallowExportedSymbol(symbolName, foundIn);
                if ( sym != NULL )
                        return (*foundIn)->getExportedSymbolAddress(sym, context, this, runResolver);
        }
        if ( weak_import ) {
                // definition can't be found anywhere, ok because it is weak, just return 0
                return 0;
        }
        throwSymbolNotFound(context, symbolName, this->getPath(), "", "flat namespace");
}


static void patchCacheUsesOf(const ImageLoader::LinkContext& context, const dyld3::closure::Image* overriddenImage,
                                                         uint32_t cacheOffsetOfImpl, const char* symbolName, uintptr_t newImpl,
                                                         DyldSharedCache::DataConstLazyScopedWriter& patcher)
{
        patcher.makeWriteable();

        uintptr_t cacheStart = (uintptr_t)context.dyldCache;
        uint32_t imageIndex = overriddenImage->imageNum() - (uint32_t)context.dyldCache->cachedDylibsImageArray()->startImageNum();
        context.dyldCache->forEachPatchableUseOfExport(imageIndex, cacheOffsetOfImpl, ^(dyld_cache_patchable_location patchLocation) {
                uintptr_t* loc = (uintptr_t*)(cacheStart+patchLocation.cacheOffset);
#if __has_feature(ptrauth_calls)
                if ( patchLocation.authenticated ) {
                         dyld3::MachOLoaded::ChainedFixupPointerOnDisk fixupInfo;
                        fixupInfo.arm64e.authRebase.auth      = true;
                        fixupInfo.arm64e.authRebase.addrDiv   = patchLocation.usesAddressDiversity;
                        fixupInfo.arm64e.authRebase.diversity = patchLocation.discriminator;
                        fixupInfo.arm64e.authRebase.key       = patchLocation.key;
                        uintptr_t newValue = fixupInfo.arm64e.signPointer(loc, newImpl + DyldSharedCache::getAddend(patchLocation));
                        if ( *loc != newValue ) {
                                *loc = newValue;
                                if ( context.verboseBind )
                                        dyld::log("dyld: cache fixup: *%p = %p (JOP: diversity 0x%04X, addr-div=%d, key=%s) to %s\n",
                                                        loc, (void*)newValue, patchLocation.discriminator, patchLocation.usesAddressDiversity, DyldSharedCache::keyName(patchLocation), symbolName);
                        }
                        return;
                }
#endif
                uintptr_t newValue = newImpl + (uintptr_t)DyldSharedCache::getAddend(patchLocation);
                if ( *loc != newValue ) {
                        *loc = newValue;
                        if ( context.verboseBind )
                                dyld::log("dyld: cache fixup: *%p = %p to %s\n", loc, (void*)newValue, symbolName);
                }
        });
}



uintptr_t ImageLoaderMachOCompressed::resolveWeak(const LinkContext& context, const char* symbolName, bool weak_import,
                                                                                                  bool runResolver, const ImageLoader** foundIn,
                                                                                                  DyldSharedCache::DataConstLazyScopedWriter& patcher)
{
        const Symbol* sym;
        CoalesceNotifier notifier = nullptr;
        __block uintptr_t   foundOutsideCache     = 0;
        __block const char* foundOutsideCachePath = nullptr;
        __block uintptr_t   lastFoundInCache      = 0;

        if ( this->usesChainedFixups() ) {
                notifier = ^(const Symbol* implSym, const ImageLoader* implIn, const mach_header* implMh) {
                        // This block is only called in dyld2 mode when a non-cached image is search for which weak-def implementation to use
                        // As a side effect of that search we notice any implementations outside and inside the cache,
                        // and use that to trigger patching the cache to use the implementation outside the cache.
                        uintptr_t implAddr = implIn->getExportedSymbolAddress(implSym, context, nullptr, false, symbolName);
                        if ( ((dyld3::MachOLoaded*)implMh)->inDyldCache() ) {
                                if ( foundOutsideCache != 0 ) {
                                        // have an implementation in cache and and earlier one not in the cache, patch cache to use earlier one
                                        lastFoundInCache = implAddr;
                                        uint32_t imageIndex;
                                        if ( context.dyldCache->findMachHeaderImageIndex(implMh, imageIndex) ) {
                                                const dyld3::closure::Image* overriddenImage = context.dyldCache->cachedDylibsImageArray()->imageForNum(imageIndex+1);
                                                uint32_t cacheOffsetOfImpl = (uint32_t)((uintptr_t)implAddr - (uintptr_t)context.dyldCache);
                                                if ( context.verboseWeakBind )
                                                        dyld::log("dyld: weak bind, patching dyld cache uses of %s to use 0x%lX in %s\n", symbolName, foundOutsideCache, foundOutsideCachePath);
                                                patchCacheUsesOf(context, overriddenImage, cacheOffsetOfImpl, symbolName, foundOutsideCache, patcher);
                                        }
                                }
                        }
                        else {
                                // record first non-cache implementation
                                if ( foundOutsideCache == 0 ) {
                                        foundOutsideCache     = implAddr;
                                        foundOutsideCachePath = implIn->getPath();
                                }
                        }
                };
        }

        if ( context.coalescedExportFinder(symbolName, &sym, foundIn, notifier) ) {
                if ( *foundIn != this )
                        context.addDynamicReference(this, const_cast<ImageLoader*>(*foundIn));
                return (*foundIn)->getExportedSymbolAddress(sym, context, this, runResolver);
        }
        // if a bundle is loaded privately the above will not find its exports
        if ( this->isBundle() && this->hasHiddenExports() ) {
                // look in self for needed symbol
                sym = this->findShallowExportedSymbol(symbolName, foundIn);
                if ( sym != NULL )
                        return (*foundIn)->getExportedSymbolAddress(sym, context, this, runResolver);
        }
        if ( weak_import ) {
                // definition can't be found anywhere, ok because it is weak, just return 0
                return 0;
        }
        throwSymbolNotFound(context, symbolName, this->getPath(), "", "weak");
}


uintptr_t ImageLoaderMachOCompressed::resolveTwolevel(const LinkContext& context, const char* symbolName, const ImageLoader* definedInImage,
                                                                                                          const ImageLoader* requestorImage, unsigned requestorOrdinalOfDef, bool weak_import, bool runResolver,
                                                                                                          const ImageLoader** foundIn)
{
        // two level lookup
        uintptr_t address;
        if ( definedInImage->findExportedSymbolAddress(context, symbolName, requestorImage, requestorOrdinalOfDef, runResolver, foundIn, &address) )
                return address;

        if ( weak_import ) {
                // definition can't be found anywhere, ok because it is weak, just return 0
                return 0;
        }

        // nowhere to be found, check if maybe this image is too new for this OS
        char versMismatch[256];
        versMismatch[0] = '\0';
        uint32_t imageMinOS = this->minOSVersion();
        // dyld is always built for the current OS, so we can get the current OS version
        // from the load command in dyld itself.
        extern const mach_header __dso_handle;
        uint32_t dyldMinOS = ImageLoaderMachO::minOSVersion(&__dso_handle);
        if ( imageMinOS > dyldMinOS ) {
#if TARGET_OS_OSX
                const char* msg = dyld::mkstringf(" (which was built for Mac OS X %d.%d)", imageMinOS >> 16, (imageMinOS >> 8) & 0xFF);
#else
                const char* msg = dyld::mkstringf(" (which was built for iOS %d.%d)", imageMinOS >> 16, (imageMinOS >> 8) & 0xFF);
#endif
                strcpy(versMismatch, msg);
                ::free((void*)msg);
        }
        throwSymbolNotFound(context, symbolName, this->getPath(), versMismatch, definedInImage->getPath());
}


uintptr_t ImageLoaderMachOCompressed::resolve(const LinkContext& context, const char* symbolName, 
                                                                                                        uint8_t symboFlags, long libraryOrdinal, const ImageLoader** targetImage,
                                                                                                        DyldSharedCache::DataConstLazyScopedWriter& patcher,
                                                                                                        LastLookup* last, bool runResolver)
{
        *targetImage = NULL;
        
        // only clients that benefit from caching last lookup pass in a LastLookup struct
        if ( last != NULL ) {
                if ( (last->ordinal == libraryOrdinal)
                        && (last->flags == symboFlags)
                        && (last->name == symbolName) ) {
                                *targetImage = last->foundIn;
                                return last->result;
                        }
        }
        
        bool weak_import = (symboFlags & BIND_SYMBOL_FLAGS_WEAK_IMPORT);
        uintptr_t symbolAddress;
        if ( context.bindFlat || (libraryOrdinal == BIND_SPECIAL_DYLIB_FLAT_LOOKUP) ) {
                symbolAddress = this->resolveFlat(context, symbolName, weak_import, runResolver, targetImage);
        }
        else if ( libraryOrdinal == BIND_SPECIAL_DYLIB_WEAK_LOOKUP ) {
                symbolAddress = this->resolveWeak(context, symbolName, weak_import, runResolver, targetImage, patcher);
        }
        else {
                if ( libraryOrdinal == BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE ) {
                        *targetImage = context.mainExecutable;
                }
                else if ( libraryOrdinal == BIND_SPECIAL_DYLIB_SELF ) {
                        *targetImage = this;
                }
                else if ( libraryOrdinal <= 0 ) {
                        dyld::throwf("bad mach-o binary, unknown special library ordinal (%ld) too big for symbol %s in %s",
                                libraryOrdinal, symbolName, this->getPath());
                }
                else if ( (unsigned)libraryOrdinal <= libraryCount() ) {
                        *targetImage = libImage((unsigned int)libraryOrdinal-1);
                }
                else {
                        dyld::throwf("bad mach-o binary, library ordinal (%ld) too big (max %u) for symbol %s in %s",
                                libraryOrdinal, libraryCount(), symbolName, this->getPath());
                }
                if ( *targetImage == NULL ) {
                        if ( weak_import ) {
                                // if target library not loaded and reference is weak or library is weak return 0
                                symbolAddress = 0;
                        }
                        else {
                                // Try get the path from the load commands
                                if ( const char* depPath = libPath((unsigned int)libraryOrdinal-1) ) {
                                        dyld::throwf("can't resolve symbol %s in %s because dependent dylib %s could not be loaded",
                                                                 symbolName, this->getPath(), depPath);
                                } else {
                                        dyld::throwf("can't resolve symbol %s in %s because dependent dylib #%ld could not be loaded",
                                                                 symbolName, this->getPath(), libraryOrdinal);
                                }
                        }
                }
                else {
                        symbolAddress = resolveTwolevel(context, symbolName, *targetImage, this, (unsigned)libraryOrdinal, weak_import, runResolver, targetImage);
                }
        }

        // save off lookup results if client wants 
        if ( last != NULL ) {
                last->ordinal   = libraryOrdinal;
                last->flags             = symboFlags;
                last->name              = symbolName;
                last->foundIn   = *targetImage;
                last->result    = symbolAddress;
        }
        
        return symbolAddress;
}

uintptr_t ImageLoaderMachOCompressed::bindAt(const LinkContext& context, ImageLoaderMachOCompressed* image,
                                                                                         uintptr_t addr, uint8_t type, const char* symbolName,
                                                                                         uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                                                         ExtraBindData *extraBindData,
                                                                                         const char* msg, DyldSharedCache::DataConstLazyScopedWriter& patcher,
                                                                                         LastLookup* last, bool runResolver)
{
        const ImageLoader*      targetImage;
        uintptr_t                       symbolAddress;
        
        // resolve symbol
    if (type == BIND_TYPE_THREADED_REBASE) {
        symbolAddress = 0;
        targetImage = nullptr;
    } else
        symbolAddress = image->resolve(context, symbolName, symbolFlags, libraryOrdinal, &targetImage, patcher, last, runResolver);

        // do actual update
        return image->bindLocation(context, image->imageBaseAddress(), addr, symbolAddress, type, symbolName, addend, image->getPath(), targetImage ? targetImage->getPath() : NULL, msg, extraBindData, image->fSlide);
}


void ImageLoaderMachOCompressed::throwBadBindingAddress(uintptr_t address, uintptr_t segmentEndAddress, int segmentIndex, 
                                                                                const uint8_t* startOpcodes, const uint8_t* endOpcodes, const uint8_t* pos)
{
        dyld::throwf("malformed binding opcodes (%ld/%ld): address 0x%08lX is outside segment %s (0x%08lX -> 0x%08lX)",
                (intptr_t)(pos-startOpcodes), (intptr_t)(endOpcodes-startOpcodes), address, segName(segmentIndex), 
                segActualLoadAddress(segmentIndex), segmentEndAddress); 
}

void ImageLoaderMachOCompressed::doBind(const LinkContext& context, bool forceLazysBound, const ImageLoader* reExportParent)
{
        CRSetCrashLogMessage2(this->getPath());

        // if prebound and loaded at prebound address, and all libraries are same as when this was prebound, then no need to bind
        // note: flat-namespace binaries need to have imports rebound (even if correctly prebound)
        if ( this->usablePrebinding(context) ) {
                // don't need to bind
                // except weak which may now be inline with the regular binds
                if ( this->participatesInCoalescing() && (fDyldInfo != nullptr) ) {
                        // run through all binding opcodes
                        DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
                        auto* patcherPtr = &patcher;
                        eachBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                                uintptr_t addr, uint8_t type, const char* symbolName,
                                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                                ExtraBindData *extraBindData,
                                                                const char* msg, LastLookup* last, bool runResolver) {
                                if ( libraryOrdinal != BIND_SPECIAL_DYLIB_WEAK_LOOKUP )
                                        return (uintptr_t)0;
                                return ImageLoaderMachOCompressed::bindAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                  addend, libraryOrdinal, extraBindData,
                                                                                                                  msg, *patcherPtr, last, runResolver);
                        });
                }
        }
        else {
                uint64_t t0 = mach_absolute_time();

                uint32_t ignore;
                bool bindingBecauseOfRoot = ( this->overridesCachedDylib(ignore) || this->inSharedCache() );
                vmAccountingSetSuspended(context, bindingBecauseOfRoot);

                if ( fChainedFixups != NULL ) {
                        DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
                        const dyld_chained_fixups_header* fixupsHeader = (dyld_chained_fixups_header*)(fLinkEditBase + fChainedFixups->dataoff);
                        doApplyFixups(context, fixupsHeader, patcher);
                }
                else if ( fDyldInfo != nullptr ) {
                #if TEXT_RELOC_SUPPORT
                        // if there are __TEXT fixups, temporarily make __TEXT writable
                        if ( fTextSegmentBinds )
                                this->makeTextSegmentWritable(context, true);
                #endif

                        // make the cache writable for this block
                        DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
                        auto* patcherPtr = &patcher;
                        if ( this->inSharedCache() )
                                patcher.makeWriteable();

                        // run through all binding opcodes
                        eachBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                                uintptr_t addr, uint8_t type, const char* symbolName,
                                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                                ExtraBindData *extraBindData,
                                                                const char* msg, LastLookup* last, bool runResolver) {
                                return ImageLoaderMachOCompressed::bindAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                  addend, libraryOrdinal, extraBindData,
                                                                                                                  msg, *patcherPtr, last, runResolver);
                        });

                #if TEXT_RELOC_SUPPORT
                        // if there were __TEXT fixups, restore write protection
                        if ( fTextSegmentBinds )
                                this->makeTextSegmentWritable(context, false);
                #endif

                        // if this image is in the shared cache, but depends on something no longer in the shared cache,
                        // there is no way to reset the lazy pointers, so force bind them now
                        if ( forceLazysBound || fInSharedCache )
                                this->doBindJustLazies(context, patcher);

                        // this image is in cache, but something below it is not.  If
                        // this image has lazy pointer to a resolver function, then
                        // the stub may have been altered to point to a shared lazy pointer.
                        if ( fInSharedCache )
                                this->updateOptimizedLazyPointers(context);
                }

                uint64_t t1 = mach_absolute_time();
                ImageLoader::fgTotalRebindCacheTime += (t1-t0);
        }

        // See if this dylib overrides something in the dyld cache
        uint32_t dyldCacheOverrideImageNum;
        if ( context.dyldCache && context.dyldCache->header.builtFromChainedFixups && overridesCachedDylib(dyldCacheOverrideImageNum) ) {

                // make the cache writable for this block
                DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
                auto* patcherPtr = &patcher;

                // need to patch all other places in cache that point to the overridden dylib, to point to this dylib instead
                const dyld3::closure::Image* overriddenImage = context.dyldCache->cachedDylibsImageArray()->imageForNum(dyldCacheOverrideImageNum);
                uint32_t imageIndex = dyldCacheOverrideImageNum - (uint32_t)context.dyldCache->cachedDylibsImageArray()->startImageNum();
                //dyld::log("doBind() found override of %s\n", this->getPath());
                context.dyldCache->forEachPatchableExport(imageIndex, ^(uint32_t cacheOffsetOfImpl, const char* exportName) {
                        uintptr_t newImpl = 0;
                        const ImageLoader* foundIn = nullptr;
                        if ( this->findExportedSymbolAddress(context, exportName, NULL, 0, false, &foundIn, &newImpl) ) {
                                //dyld::log("   patchCacheUsesOf(%s) found in %s\n", exportName, foundIn->getPath());
                                patchCacheUsesOf(context, overriddenImage, cacheOffsetOfImpl, exportName, newImpl, *patcherPtr);
                        }
                        else {
                                // <rdar://problem/59196856> allow patched impls to move between re-export sibling dylibs
                                if ( reExportParent != nullptr ) {
                                        reExportParent->forEachReExportDependent(^(const ImageLoader* reExportedDep, bool& stop) {
                                                uintptr_t siblingImpl = 0;
                                                const ImageLoader* foundInSibling = nullptr;
                                                if ( reExportedDep->findExportedSymbolAddress(context, exportName, NULL, 0, false, &foundInSibling, &siblingImpl) ) {
                                                        stop = true;
                                                        //dyld::log("   patchCacheUsesOf(%s) found in sibling %s\n", exportName, foundInSibling->getPath());
                                                        patchCacheUsesOf(context, overriddenImage, cacheOffsetOfImpl, exportName, siblingImpl, *patcherPtr);
                                                }
                                        });
                                }
                        }
                });
        }

        // set up dyld entry points in image
        // do last so flat main executables will have __dyld or __program_vars set up
        this->setupLazyPointerHandler(context);
        CRSetCrashLogMessage2(NULL);
}


void ImageLoaderMachOCompressed::doBindJustLazies(const LinkContext& context, DyldSharedCache::DataConstLazyScopedWriter& patcher)
{
        eachLazyBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                        uintptr_t addr, uint8_t type, const char* symbolName,
                                                        uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                        ExtraBindData *extraBindData,
                                                        const char* msg, LastLookup* last, bool runResolver) {
                return ImageLoaderMachOCompressed::bindAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                  addend, libraryOrdinal, extraBindData,
                                                                                                  msg, patcher, last, runResolver);
        });
}

void ImageLoaderMachOCompressed::doApplyFixups(const LinkContext& context, const dyld_chained_fixups_header* fixupsHeader,
                                                                                           DyldSharedCache::DataConstLazyScopedWriter& patcher)
{
        const dyld3::MachOLoaded* ml = (dyld3::MachOLoaded*)machHeader();
        const dyld_chained_starts_in_image* starts = (dyld_chained_starts_in_image*)((uint8_t*)fixupsHeader + fixupsHeader->starts_offset);

        // build table of resolved targets for each symbol ordinal
        STACK_ALLOC_OVERFLOW_SAFE_ARRAY(const void*, targetAddrs, 128);
        targetAddrs.reserve(fixupsHeader->imports_count);
        __block Diagnostics diag;
        const dyld3::MachOAnalyzer* ma = (dyld3::MachOAnalyzer*)ml;
        ma->forEachChainedFixupTarget(diag, ^(int libOrdinal, const char* symbolName, uint64_t addend, bool weakImport, bool& stop) {
                const ImageLoader*      targetImage;
                uint8_t symbolFlags = weakImport ? BIND_SYMBOL_FLAGS_WEAK_IMPORT : 0;
                try {
                        uintptr_t symbolAddress = this->resolve(context, symbolName, symbolFlags, libOrdinal, &targetImage, patcher, NULL, true);
                        targetAddrs.push_back((void*)(symbolAddress + addend));
                }
                catch (const char* msg) {
                        stop = true;
                        diag.error("%s", msg);
                }
        });
        if ( diag.hasError() )
                throw strdup(diag.errorMessage());

        auto logFixups = ^(void* loc, void* newValue) {
                dyld::log("dyld: fixup: %s:%p = %p\n", this->getShortName(), loc, newValue);
        };
        if ( !context.verboseBind )
                logFixups = nullptr;

        ml->fixupAllChainedFixups(diag, starts, fSlide, targetAddrs, logFixups);
        if ( diag.hasError() )
                throw strdup(diag.errorMessage());
}

void ImageLoaderMachOCompressed::registerInterposing(const LinkContext& context)
{
        // mach-o files advertise interposing by having a __DATA __interpose section
        struct InterposeData { uintptr_t replacement; uintptr_t replacee; };

        // FIDME: It seems wrong to need a patcher here, but resolve may call resolveWeak and patch the cache.
        // That would require weak symbols in the interposing section though, which may not be supported.
        DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
        auto* patcherPtr = &patcher;

        __block Diagnostics diag;
        const dyld3::MachOAnalyzer* ma = (dyld3::MachOAnalyzer*)fMachOData;
        ma->forEachInterposingSection(diag, ^(uint64_t vmOffset, uint64_t vmSize, bool& stopSections) {
                if ( ma->hasChainedFixups() ) {
            const uint16_t pointerFormat = ma->chainedPointerFormat();
                        const uint8_t* sectionStart = fMachOData+vmOffset;
                        const uint8_t* sectionEnd   = fMachOData+vmOffset+vmSize;
                ma->withChainStarts(diag, ma->chainStartsOffset(), ^(const dyld_chained_starts_in_image* startsInfo) {
                        __block uintptr_t lastRebaseTarget = 0;
                                ma->forEachFixupInAllChains(diag, startsInfo, false, ^(dyld3::MachOLoaded::ChainedFixupPointerOnDisk* fixupLoc, const dyld_chained_starts_in_segment* segInfo, bool& stopFixups) {
                                        if ( ((uint8_t*)fixupLoc < sectionStart) || ((uint8_t*)fixupLoc >= sectionEnd) )
                                                return;
                                        uint64_t rebaseTargetRuntimeOffset;
                                        uint32_t bindOrdinal;
                                        int64_t  ptrAddend;
                                if ( fixupLoc->isRebase(pointerFormat, 0, rebaseTargetRuntimeOffset) ) {
                                                //dyld::log("interpose rebase at fixup at %p to 0x%0llX\n", fixupLoc, rebaseTargetRuntimeOffset);
                                                lastRebaseTarget = (uintptr_t)(fMachOData+rebaseTargetRuntimeOffset);
                                }
                                else if ( fixupLoc->isBind(pointerFormat, bindOrdinal, ptrAddend) ) {
                                                //dyld::log("interpose bind fixup at %p to bind ordinal %d\n", fixupLoc, bindOrdinal);
                                                __block uint32_t targetBindIndex = 0;
                                                ma->forEachChainedFixupTarget(diag, ^(int libraryOrdinal, const char* symbolName, uint64_t addend, bool weakImport, bool& stop) {
                                                        if ( targetBindIndex == bindOrdinal ) {
                                                                //dyld::log("interpose bind fixup at %p is to %s libOrdinal=%d\n", fixupLoc, symbolName, libraryOrdinal);
                                                                LastLookup* last = NULL;
                                                                const ImageLoader* targetImage;
                                                                uintptr_t targetBindAddress = 0;
                                                                try {
                                                                        targetBindAddress = this->resolve(context, symbolName, 0, libraryOrdinal, &targetImage, *patcherPtr, last, false);
                                                                }
                                                                catch (const char* msg) {
                                                                        if ( !weakImport )
                                                                                throw msg;
                                                                        targetBindAddress = 0;
                                                                }
                                                                //dyld::log("interpose bind fixup at %p is bound to 0x%lX\n", fixupLoc, targetBindAddress);
                                                                // <rdar://problem/25686570> ignore interposing on a weak function that does not exist
                                                                if ( targetBindAddress == 0 )
                                                                        return;
                                                                ImageLoader::InterposeTuple tuple;
                                                                tuple.replacement   = lastRebaseTarget;
                                                                tuple.neverImage        = this;
                                                                tuple.onlyImage         = NULL;
                                                                tuple.replacee      = targetBindAddress;
                                                                // <rdar://problem/7937695> verify that replacement is in this image
                                                                if ( this->containsAddress((void*)tuple.replacement) ) {
                                                                        if ( context.verboseInterposing )
                                                                                dyld::log("dyld: interposing 0x%lx with 0x%lx\n", tuple.replacee, tuple.replacement);
                                                                        // chain to any existing interpositions
                                                                        for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
                                                                                if ( it->replacee == tuple.replacee ) {
                                                                                        tuple.replacee = it->replacement;
                                                                                }
                                                                        }
                                                                        ImageLoader::fgInterposingTuples.push_back(tuple);
                                                                }
                                                        }
                                                        ++targetBindIndex;
                                                });
                                        }
                                });
                        });
                }
                else {
                        // traditional (non-chained) fixups
                        const size_t         count          = (size_t)(vmSize / sizeof(InterposeData));
                        const InterposeData* interposeArray = (InterposeData*)(fMachOData+vmOffset);
                        if ( context.verboseInterposing )
                                dyld::log("dyld: found %lu interposing tuples in %s\n", count, getPath());
                        for (size_t j=0; j < count; ++j) {
                                uint64_t bindOffset = ((uint8_t*)&(interposeArray[j].replacee)) - fMachOData;
                                ma->forEachBind(diag, ^(uint64_t runtimeOffset, int libOrdinal, const char* symbolName, bool weakImport, bool lazyBind, uint64_t addend, bool& stopBinds) {
                                        if ( bindOffset != runtimeOffset )
                                                return;
                                        stopBinds = true;
                                        LastLookup* last = NULL;
                                        const ImageLoader* targetImage;
                                        uintptr_t targetBindAddress = 0;
                                        try {
                                                targetBindAddress = this->resolve(context, symbolName, 0, libOrdinal, &targetImage, *patcherPtr, last, false);
                                        }
                                        catch (const char* msg) {
                                                if ( !weakImport )
                                                        throw msg;
                                                targetBindAddress = 0;
                                        }
                                        ImageLoader::InterposeTuple tuple;
                                        tuple.replacement     = interposeArray[j].replacement;
                                        tuple.neverImage      = this;
                                        tuple.onlyImage       = NULL;
                                        tuple.replacee        = targetBindAddress;
                                        // <rdar://problem/25686570> ignore interposing on a weak function that does not exist
                                        if ( tuple.replacee == 0 )
                                                return;
                                        // <rdar://problem/7937695> verify that replacement is in this image
                                        if ( this->containsAddress((void*)tuple.replacement) ) {
                                                if ( context.verboseInterposing )
                                                        dyld::log("dyld:   interposing 0x%lx with 0x%lx\n", tuple.replacee, tuple.replacement);
                                                // chain to any existing interpositions
                                                for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
                                                        if ( it->replacee == tuple.replacee ) {
                                                                tuple.replacee = it->replacement;
                                                        }
                                                }
                                                ImageLoader::fgInterposingTuples.push_back(tuple);
                                        }
                                }, ^(const char* symbolName){
                                });
                        }
                }
        });
}

bool ImageLoaderMachOCompressed::usesChainedFixups() const
{
        return ((dyld3::MachOLoaded*)machHeader())->hasChainedFixups();
}

struct ThreadedBindData {
    ThreadedBindData(const char* symbolName, int64_t addend, long libraryOrdinal, uint8_t symbolFlags, uint8_t type)
    : symbolName(symbolName), addend(addend), libraryOrdinal(libraryOrdinal), symbolFlags(symbolFlags), type(type) { }

    std::tuple<const char*, int64_t, long, bool, uint8_t> pack() const {
        return std::make_tuple(symbolName, addend, libraryOrdinal, symbolFlags, type);
    }

    const char* symbolName     = nullptr;
    int64_t addend             = 0;
    long libraryOrdinal        = 0;
    uint8_t symbolFlags        = 0;
    uint8_t type               = 0;
};

void ImageLoaderMachOCompressed::makeDataReadOnly() const
{
#if !TEXT_RELOC_SUPPORT
        if ( fReadOnlyDataSegment && !this->ImageLoader::inSharedCache() ) {
                for (unsigned int i=0; i < fSegmentsCount; ++i) {
                        if ( segIsReadOnlyData(i) ) {
                                uintptr_t start = segActualLoadAddress(i);
                                uintptr_t size = segSize(i);
        #if defined(__x86_64__) && !TARGET_OS_SIMULATOR
                                if ( dyld::isTranslated() ) {
                                        // <rdar://problem/48325338> can't mprotect non-16KB segments
                                        if ( ((size & 0x3FFF) != 0) || ((start & 0x3FFF) != 0) )
                                                continue;
                                }
        #endif
                                ::mprotect((void*)start, size, PROT_READ);
                                //dyld::log("make read-only 0x%09lX -> 0x%09lX\n", (long)start, (long)(start+size));
                        }
                }
        }
#endif
}


void ImageLoaderMachOCompressed::eachBind(const LinkContext& context, bind_handler handler)
{
    try {
                uint8_t type = 0;
                int segmentIndex = -1;
                uintptr_t address = segActualLoadAddress(0);
                uintptr_t segmentStartAddress = segActualLoadAddress(0);
                uintptr_t segmentEndAddress = segActualEndAddress(0);
                const char* symbolName = NULL;
                uint8_t symboFlags = 0;
                bool libraryOrdinalSet = false;
                long libraryOrdinal = 0;
                intptr_t addend = 0;
                uintptr_t count;
                uintptr_t skip;
        uintptr_t segOffset = 0;

                dyld3::OverflowSafeArray<ThreadedBindData> ordinalTable;
        bool useThreadedRebaseBind = false;
        ExtraBindData extraBindData;
                LastLookup last = { 0, 0, NULL, 0, NULL };
                const uint8_t* const start = fLinkEditBase + fDyldInfo->bind_off;
                const uint8_t* const end = &start[fDyldInfo->bind_size];
                const uint8_t* p = start;
                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;
                                        libraryOrdinalSet = true;
                                        break;
                                case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
                                        libraryOrdinal = read_uleb128(p, end);
                                        libraryOrdinalSet = true;
                                        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;
                                        }
                                        libraryOrdinalSet = true;
                                        break;
                                case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
                                        symbolName = (char*)p;
                                        symboFlags = immediate;
                                        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;
                                        if ( (segmentIndex >= fSegmentsCount) || (segmentIndex < 0) )
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is out of range (0..%d)",
                                                                segmentIndex, fSegmentsCount-1);
                        #if TEXT_RELOC_SUPPORT
                                        if ( !segWriteable(segmentIndex) && !segHasRebaseFixUps(segmentIndex) && !segHasBindFixUps(segmentIndex) )
                        #else
                                        if ( !segWriteable(segmentIndex) )
                        #endif
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is not writable", segmentIndex);
                                        segOffset = read_uleb128(p, end);
                                        if ( segOffset > segSize(segmentIndex) )
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has offset 0x%08lX beyond segment size (0x%08lX)", segOffset, segSize(segmentIndex));
                                        segmentStartAddress = segActualLoadAddress(segmentIndex);
                                        address = segmentStartAddress + segOffset;
                                        segmentEndAddress = segActualEndAddress(segmentIndex);
                                        break;
                                case BIND_OPCODE_ADD_ADDR_ULEB:
                                        address += read_uleb128(p, end);
                                        break;
                                case BIND_OPCODE_DO_BIND:
                    if (!useThreadedRebaseBind) {
                        if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                            throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                        if ( symbolName  == NULL )
                            dyld::throwf("BIND_OPCODE_DO_BIND missing preceding BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM");
                        if ( segmentIndex == -1 )
                            dyld::throwf("BIND_OPCODE_DO_BIND missing preceding BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB");
                        if ( !libraryOrdinalSet )
                            dyld::throwf("BIND_OPCODE_DO_BIND missing preceding BIND_OPCODE_SET_DYLIB_ORDINAL*");
                        handler(context, this, address, type, symbolName, symboFlags, addend, libraryOrdinal,
                                                                &extraBindData, "", &last, false);
                        address += sizeof(intptr_t);
                    } else {
                        ordinalTable.push_back(ThreadedBindData(symbolName, addend, libraryOrdinal, symboFlags, type));
                    }
                                        break;
                                case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
                                        if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                        if ( symbolName  == NULL )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB missing preceding BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM");
                                        if ( segmentIndex == -1 )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB missing preceding BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB");
                                        if ( !libraryOrdinalSet )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB missing preceding BIND_OPCODE_SET_DYLIB_ORDINAL*");
                    handler(context, this, address, type, symbolName, symboFlags, addend, libraryOrdinal,
                                     &extraBindData, "", &last, false);
                                        address += read_uleb128(p, end) + sizeof(intptr_t);
                                        break;
                                case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
                                        if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                        if ( symbolName  == NULL )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED missing preceding BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM");
                                        if ( segmentIndex == -1 )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED missing preceding BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB");
                                        if ( !libraryOrdinalSet )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED missing preceding BIND_OPCODE_SET_DYLIB_ORDINAL*");
                    handler(context, this, address, type, symbolName, symboFlags, addend, libraryOrdinal,
                                     &extraBindData, "", &last, false);
                                        address += immediate*sizeof(intptr_t) + sizeof(intptr_t);
                                        break;
                                case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
                                        if ( symbolName  == NULL )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB missing preceding BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM");
                                        if ( segmentIndex == -1 )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB missing preceding BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB");
                                        count = read_uleb128(p, end);
                                        if ( !libraryOrdinalSet )
                                                dyld::throwf("BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB missing preceding BIND_OPCODE_SET_DYLIB_ORDINAL*");
                                        skip = read_uleb128(p, end);
                                        for (uint32_t i=0; i < count; ++i) {
                                                if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                        throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                        handler(context, this, address, type, symbolName, symboFlags, addend, libraryOrdinal,
                                         &extraBindData, "", &last, false);
                                                address += skip + sizeof(intptr_t);
                                        }
                    break;
                case BIND_OPCODE_THREADED:
                    if (sizeof(intptr_t) != 8) {
                        dyld::throwf("BIND_OPCODE_THREADED require 64-bit");
                        return;
                    }
                    // Note the immediate is a sub opcode
                    switch (immediate) {
                        case BIND_SUBOPCODE_THREADED_SET_BIND_ORDINAL_TABLE_SIZE_ULEB:
                            count = read_uleb128(p, end);
                            ordinalTable.clear();
                            // FIXME: ld64 wrote the wrong value here and we need to offset by 1 for now.
                            ordinalTable.reserve(count + 1);
                            useThreadedRebaseBind = true;
                            break;
                        case BIND_SUBOPCODE_THREADED_APPLY: {
                            uint64_t delta = 0;
                            do {
                                address = segmentStartAddress + segOffset;
                                uint64_t value = *(uint64_t*)address;


                                bool isRebase = (value & (1ULL << 62)) == 0;
                                if (isRebase) {
                                    {
                                        // Call the bind handler which knows about our bind type being set to rebase
                                        handler(context, this, address, BIND_TYPE_THREADED_REBASE, nullptr, 0, 0, 0,
                                                         nullptr, "", &last, false);
                                    }
                                } else {
                                    // the ordinal is bits [0..15]
                                    uint16_t ordinal = value & 0xFFFF;
                                    if (ordinal >= ordinalTable.count()) {
                                        dyld::throwf("bind ordinal (%d) is out of range (max=%lu) for disk pointer 0x%16llX at segIndex=%d, segOffset=0x%0lX in %s",
                                                    ordinal, ordinalTable.count(),value, segmentIndex, segOffset, this->getPath());
                                        return;
                                    }
                                    std::tie(symbolName, addend, libraryOrdinal, symboFlags, type) = ordinalTable[ordinal].pack();
                                    if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                        throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                    {
                                        handler(context, this, address, BIND_TYPE_THREADED_BIND,
                                                         symbolName, symboFlags, addend, libraryOrdinal,
                                                         nullptr, "", &last, false);
                                    }
                                }

                                // The delta is bits [51..61]
                                // And bit 62 is to tell us if we are a rebase (0) or bind (1)
                                value &= ~(1ULL << 62);
                                delta = ( value & 0x3FF8000000000000 ) >> 51;
                                segOffset += delta * sizeof(intptr_t);
                            } while ( delta != 0 );
                            break;
                        }

                        default:
                            dyld::throwf("bad threaded bind subopcode 0x%02X", *p);
                    }
                    break;
                                default:
                                        dyld::throwf("bad bind opcode %d in bind info", *p);
                        }
                }
        }
        catch (const char* msg) {
                const char* newMsg = dyld::mkstringf("%s in %s", msg, this->getPath());
                free((void*)msg);
                throw newMsg;
        }
}

void ImageLoaderMachOCompressed::eachLazyBind(const LinkContext& context, bind_handler handler)
{
        try {
                uint8_t type = BIND_TYPE_POINTER;
                int segmentIndex = -1;
                uintptr_t address = segActualLoadAddress(0);
                uintptr_t segmentStartAddress = segActualLoadAddress(0);
                uintptr_t segmentEndAddress = segActualEndAddress(0);
                uintptr_t segOffset;
                const char* symbolName = NULL;
                uint8_t symboFlags = 0;
                long libraryOrdinal = 0;
                intptr_t addend = 0;
                const uint8_t* const start = fLinkEditBase + fDyldInfo->lazy_bind_off;
                const uint8_t* const end = &start[fDyldInfo->lazy_bind_size];
                const uint8_t* p = start;
                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:
                                        // there is BIND_OPCODE_DONE at end of each lazy bind, don't stop until end of whole sequence
                                        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:
                                        symbolName = (char*)p;
                                        symboFlags = immediate;
                                        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;
                                        if ( (segmentIndex >= fSegmentsCount) || (segmentIndex < 0) )
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is out of range (0..%d)",
                                                                segmentIndex, fSegmentsCount-1);
                                        if ( !segWriteable(segmentIndex) )
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is not writable", segmentIndex);
                                        segOffset = read_uleb128(p, end);
                                        if ( segOffset > segSize(segmentIndex) )
                                                dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has offset 0x%08lX beyond segment size (0x%08lX)", segOffset, segSize(segmentIndex));
                                        segmentStartAddress = segActualLoadAddress(segmentIndex);
                                        segmentEndAddress = segActualEndAddress(segmentIndex);
                                        address = segmentStartAddress + segOffset;
                                        break;
                                case BIND_OPCODE_ADD_ADDR_ULEB:
                                        address += read_uleb128(p, end);
                                        break;
                                case BIND_OPCODE_DO_BIND:
                                        if ( segmentIndex == -1 )
                                                dyld::throwf("BIND_OPCODE_DO_BIND missing preceding BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB");
                                        if ( (address < segmentStartAddress) || (address >= segmentEndAddress) )
                                                throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
                                        if ( symbolName  == NULL )
                                                dyld::throwf("BIND_OPCODE_DO_BIND missing preceding BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM");
                    handler(context, this, address, type, symbolName, symboFlags, addend, libraryOrdinal,
                                     NULL, "forced lazy ", NULL, false);
                                        address += sizeof(intptr_t);
                                        break;
                                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:
                                        dyld::throwf("bad lazy bind opcode %d", *p);
                        }
                }
        }  

        catch (const char* msg) {
                const char* newMsg = dyld::mkstringf("%s in %s", msg, this->getPath());
                free((void*)msg);
                throw newMsg;
        }
}

// A program built targeting 10.5 will have hybrid stubs.  When used with weak symbols
// the classic lazy loader is used even when running on 10.6
uintptr_t ImageLoaderMachOCompressed::doBindLazySymbol(uintptr_t* lazyPointer, const LinkContext& context,
                                                                                                           DyldSharedCache::DataConstLazyScopedWriter& patcher)
{
        // only works with compressed LINKEDIT if classic symbol table is also present
        const macho_nlist* symbolTable = NULL;
        const char* symbolTableStrings = NULL;
        const dysymtab_command* dynSymbolTable = NULL;
        const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
        const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
        const struct load_command* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                switch (cmd->cmd) {
                        case LC_SYMTAB:
                                {
                                        const struct symtab_command* symtab = (struct symtab_command*)cmd;
                                        symbolTableStrings = (const char*)&fLinkEditBase[symtab->stroff];
                                        symbolTable = (macho_nlist*)(&fLinkEditBase[symtab->symoff]);
                                }
                                break;
                        case LC_DYSYMTAB:
                                dynSymbolTable = (struct dysymtab_command*)cmd;
                                break;
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }
        // no symbol table => no lookup by address
        if ( (symbolTable == NULL) || (dynSymbolTable == NULL) )
                dyld::throwf("classic lazy binding used with compressed LINKEDIT at %p in image %s", lazyPointer, this->getPath());

        // scan for all lazy-pointer sections
        const bool twoLevel = this->usesTwoLevelNameSpace();
        const uint32_t* const indirectTable = (uint32_t*)&fLinkEditBase[dynSymbolTable->indirectsymoff];
        cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                switch (cmd->cmd) {
                        case LC_SEGMENT_COMMAND:
                                {
                                        const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
                                        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
                                        const struct macho_section* const sectionsEnd = &sectionsStart[seg->nsects];
                                        for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
                                                const uint8_t type = sect->flags & SECTION_TYPE;
                                                uint32_t symbolIndex = INDIRECT_SYMBOL_LOCAL;
                                                if ( type == S_LAZY_SYMBOL_POINTERS ) {
                                                        const size_t pointerCount = sect->size / sizeof(uintptr_t);
                                                        uintptr_t* const symbolPointers = (uintptr_t*)(sect->addr + fSlide);
                                                        if ( (lazyPointer >= symbolPointers) && (lazyPointer < &symbolPointers[pointerCount]) ) {
                                                                const uint32_t indirectTableOffset = sect->reserved1;
                                                                const size_t lazyIndex = lazyPointer - symbolPointers;
                                                                symbolIndex = indirectTable[indirectTableOffset + lazyIndex];
                                                        }
                                                }
                                                if ( (symbolIndex != INDIRECT_SYMBOL_ABS) && (symbolIndex != INDIRECT_SYMBOL_LOCAL) ) {
                                                        const macho_nlist* symbol = &symbolTable[symbolIndex];
                                                        const char* symbolName = &symbolTableStrings[symbol->n_un.n_strx];
                                                        int libraryOrdinal = GET_LIBRARY_ORDINAL(symbol->n_desc);
                                                        if ( !twoLevel || context.bindFlat ) 
                                                                libraryOrdinal = BIND_SPECIAL_DYLIB_FLAT_LOOKUP;
                                                        uintptr_t ptrToBind = (uintptr_t)lazyPointer;
                            uintptr_t symbolAddr = bindAt(context, this, ptrToBind, BIND_TYPE_POINTER, symbolName, 0, 0, libraryOrdinal,
                                                          NULL, "lazy ", patcher, NULL);
                                                        ++fgTotalLazyBindFixups;
                                                        return symbolAddr;
                                                }
                                        }
                                }
                                break;
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }
        dyld::throwf("lazy pointer not found at address %p in image %s", lazyPointer, this->getPath());
}



uintptr_t ImageLoaderMachOCompressed::doBindFastLazySymbol(uint32_t lazyBindingInfoOffset, const LinkContext& context,
                                                                                                                        void (*lock)(), void (*unlock)())
{
        // <rdar://problem/8663923> race condition with flat-namespace lazy binding
        if ( this->usesTwoLevelNameSpace() ) {
                // two-level namespace lookup does not require lock because dependents can't be unloaded before this image
        }
        else {
                // acquire dyld global lock
                if ( lock != NULL )
                        lock();
        }

        DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
        
        const uint8_t* const start = fLinkEditBase + fDyldInfo->lazy_bind_off;
        const uint8_t* const end = &start[fDyldInfo->lazy_bind_size];
        uint8_t segIndex;
        uintptr_t segOffset;
        int libraryOrdinal;
        const char* symbolName;
        bool doneAfterBind;
        uintptr_t result;
        do {
                if ( ! getLazyBindingInfo(lazyBindingInfoOffset, start, end, &segIndex, &segOffset, &libraryOrdinal, &symbolName, &doneAfterBind) )
                        dyld::throwf("bad lazy bind info");

                if ( segIndex >= fSegmentsCount )
                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is too large (0..%d)", 
                                                        segIndex, fSegmentsCount-1);
                if ( segOffset > segSize(segIndex) )
                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has offset 0x%08lX beyond segment size (0x%08lX)", segOffset, segSize(segIndex));
                uintptr_t address = segActualLoadAddress(segIndex) + segOffset;
        result = bindAt(context, this, address, BIND_TYPE_POINTER, symbolName, 0, 0, libraryOrdinal,
                              NULL, "lazy ", patcher, NULL, true);
                // <rdar://problem/24140465> Some old apps had multiple lazy symbols bound at once
        } while (!doneAfterBind && !context.strictMachORequired);

        if ( !this->usesTwoLevelNameSpace() ) {
                // release dyld global lock
                if ( unlock != NULL )
                        unlock();
        }
        return result;
}

void ImageLoaderMachOCompressed::initializeCoalIterator(CoalIterator& it, unsigned int loadOrder, unsigned)
{
        it.image = this;
        it.symbolName = " ";
        it.loadOrder = loadOrder;
        it.weakSymbol = false;
        it.symbolMatches = false;
        it.done = false;
        it.curIndex = 0;
        it.endIndex = (this->fDyldInfo ? this->fDyldInfo->weak_bind_size : 0);
        it.address = 0;
        it.type = 0;
        it.addend = 0;
}


bool ImageLoaderMachOCompressed::incrementCoalIterator(CoalIterator& it)
{
        if ( it.done )
                return false;
                
        if ( (this->fDyldInfo == nullptr) || (this->fDyldInfo->weak_bind_size == 0) ) {
                /// hmmm, ld set MH_WEAK_DEFINES or MH_BINDS_TO_WEAK, but there is no weak binding info
                it.done = true;
                it.symbolName = "~~~";
                return true;
        }
        const uint8_t* start = fLinkEditBase + fDyldInfo->weak_bind_off;
        const uint8_t* p = start + it.curIndex;
        const uint8_t* end = fLinkEditBase + fDyldInfo->weak_bind_off + this->fDyldInfo->weak_bind_size;
        uintptr_t count;
        uintptr_t skip;
        uintptr_t segOffset;
        while ( p < end ) {
                uint8_t immediate = *p & BIND_IMMEDIATE_MASK;
                uint8_t opcode = *p & BIND_OPCODE_MASK;
                ++p;
                switch (opcode) {
                        case BIND_OPCODE_DONE:
                                it.done = true;
                                it.curIndex = p - start;
                                it.symbolName = "~~~"; // sorts to end
                                return true;
                        case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
                                it.symbolName = (char*)p;
                                it.weakSymbol = ((immediate & BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION) == 0);
                                it.symbolMatches = false;
                                while (*p != '\0')
                                        ++p;
                                ++p;
                                it.curIndex = p - start;
                                return false;
                        case BIND_OPCODE_SET_TYPE_IMM:
                                it.type = immediate;
                                break;
                        case BIND_OPCODE_SET_ADDEND_SLEB:
                                it.addend = read_sleb128(p, end);
                                break;
                        case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
                                if ( immediate >= fSegmentsCount )
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is too large (0..%d)",
                                                        immediate, fSegmentsCount-1);
                #if __arm__
                                // <rdar://problem/23138428> iOS app compatibility
                                if ( !segWriteable(immediate) && it.image->isPositionIndependentExecutable() )
                #elif TEXT_RELOC_SUPPORT
                                // <rdar://problem/23479396&23590867> i386 OS X app compatibility
                                if ( !segWriteable(immediate) && !segHasRebaseFixUps(immediate) && !segHasBindFixUps(immediate)
                                        && (!it.image->isExecutable() || it.image->isPositionIndependentExecutable()) )
                #else
                                if ( !segWriteable(immediate) )
        #endif
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB targets segment %s which is not writable", segName(immediate));
                                segOffset = read_uleb128(p, end);
                                if ( segOffset > segSize(immediate) )
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has offset 0x%08lX beyond segment size (0x%08lX)", segOffset, segSize(immediate));
                                it.address = segActualLoadAddress(immediate) + segOffset;
                                break;
                        case BIND_OPCODE_ADD_ADDR_ULEB:
                                it.address += read_uleb128(p, end);
                                break;
                        case BIND_OPCODE_DO_BIND:
                                it.address += sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
                                it.address += read_uleb128(p, end) + sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
                                it.address += immediate*sizeof(intptr_t) + sizeof(intptr_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) {
                                        it.address += skip + sizeof(intptr_t);
                                }
                                break;
                        default:
                                dyld::throwf("bad weak bind opcode '%d' found after processing %d bytes in '%s'", *p, (int)(p-start), this->getPath());
                }
        }
        /// hmmm, BIND_OPCODE_DONE is missing...
        it.done = true;
        it.symbolName = "~~~";
        //dyld::log("missing BIND_OPCODE_DONE for image %s\n", this->getPath());
        return true;
}

uintptr_t ImageLoaderMachOCompressed::getAddressCoalIterator(CoalIterator& it, const LinkContext& context)
{
        //dyld::log("looking for %s in %s\n", it.symbolName, this->getPath());
        const ImageLoader* foundIn = NULL;
        const ImageLoader::Symbol* sym = this->findShallowExportedSymbol(it.symbolName, &foundIn);
        if ( sym != NULL ) {
                //dyld::log("sym=%p, foundIn=%p\n", sym, foundIn);
                return foundIn->getExportedSymbolAddress(sym, context, this);
        }
        return 0;
}


void ImageLoaderMachOCompressed::updateUsesCoalIterator(CoalIterator& it, uintptr_t value, ImageLoader* targetImage, unsigned targetIndex, const LinkContext& context)
{
        // <rdar://problem/6570879> weak binding done too early with inserted libraries
        if ( this->getState() < dyld_image_state_bound  )
                return;

        if ( fDyldInfo == nullptr )
                return;
                
        const uint8_t* start = fLinkEditBase + fDyldInfo->weak_bind_off;
        const uint8_t* p = start + it.curIndex;
        const uint8_t* end = fLinkEditBase + fDyldInfo->weak_bind_off + this->fDyldInfo->weak_bind_size;

        uint8_t type = it.type;
        uintptr_t address = it.address;
        const char* symbolName = it.symbolName;
        intptr_t addend = it.addend;
        uintptr_t count;
        uintptr_t skip;
        uintptr_t segOffset;
        bool done = false;
        bool boundSomething = 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_SYMBOL_TRAILING_FLAGS_IMM:
                                done = true;
                                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:
                                if ( immediate >= fSegmentsCount )
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment %d which is too large (0..%d)",
                                                        immediate, fSegmentsCount-1);
                #if __arm__
                                // <rdar://problem/23138428> iOS app compatibility
                                if ( !segWriteable(immediate) && it.image->isPositionIndependentExecutable() )
                #elif TEXT_RELOC_SUPPORT
                                // <rdar://problem/23479396&23590867> i386 OS X app compatibility
                                if ( !segWriteable(immediate) && !segHasRebaseFixUps(immediate) && !segHasBindFixUps(immediate)
                                        && (!it.image->isExecutable() || it.image->isPositionIndependentExecutable()) )
                #else
                                if ( !segWriteable(immediate) )
        #endif
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB targets segment %s which is not writable", segName(immediate));
                                segOffset = read_uleb128(p, end);
                                if ( segOffset > segSize(immediate) )
                                        dyld::throwf("BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has offset 0x%08lX beyond segment size (0x%08lX)", segOffset, segSize(immediate));
                                address = segActualLoadAddress(immediate) + segOffset;
                                break;
                        case BIND_OPCODE_ADD_ADDR_ULEB:
                                address += read_uleb128(p, end);
                                break;
                        case BIND_OPCODE_DO_BIND:
                                bindLocation(context, this->imageBaseAddress(), address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ", NULL, fSlide);
                                boundSomething = true;
                                address += sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
                                bindLocation(context, this->imageBaseAddress(), address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ", NULL, fSlide);
                                boundSomething = true;
                                address += read_uleb128(p, end) + sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
                                bindLocation(context, this->imageBaseAddress(), address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ", NULL, fSlide);
                                boundSomething = true;
                                address += immediate*sizeof(intptr_t) + sizeof(intptr_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) {
                                        bindLocation(context, this->imageBaseAddress(), address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ", NULL, fSlide);
                                        boundSomething = true;
                                        address += skip + sizeof(intptr_t);
                                }
                                break;
                        default:
                                dyld::throwf("bad bind opcode %d in weak binding info", *p);
                }
        }
        // C++ weak coalescing cannot be tracked by reference counting.  Error on side of never unloading.
        if ( boundSomething && (targetImage != this) )
                context.addDynamicReference(this, targetImage);
}

uintptr_t ImageLoaderMachOCompressed::interposeAt(const LinkContext& context, ImageLoaderMachOCompressed* image,
                                                                                                  uintptr_t addr, uint8_t type, const char*,
                                                  uint8_t, intptr_t, long,
                                                  ExtraBindData *extraBindData,
                                                  const char*, LastLookup*, bool runResolver)
{
        if ( type == BIND_TYPE_POINTER ) {
                uintptr_t* fixupLocation = (uintptr_t*)addr;
                uintptr_t curValue = *fixupLocation;
                uintptr_t newValue = interposedAddress(context, curValue, image);
                if ( newValue != curValue) {
                        *fixupLocation = newValue;
                }
        }
        return 0;
}

void ImageLoaderMachOCompressed::doInterpose(const LinkContext& context)
{
        if ( context.verboseInterposing )
                dyld::log("dyld: interposing %lu tuples onto image: %s\n", fgInterposingTuples.size(), this->getPath());

        const dyld3::MachOAnalyzer* ma = (dyld3::MachOAnalyzer*)fMachOData;
        if ( !ma->hasChainedFixups() && (fDyldInfo != nullptr) ) {
                // Note: all binds that happen as part of normal loading and fixups will have interposing applied.
                // There is only two cases where we need to parse bind opcodes and apply interposing:

                // make the cache writable for this block
                DyldSharedCache::DataConstLazyScopedWriter patcher(context.dyldCache, mach_task_self(), context.verboseMapping ? &dyld::log : nullptr);
                if ( ma->inDyldCache() )
                        patcher.makeWriteable();

                // 1) Lazy pointers are either not bound yet, or in dyld cache they are prebound (to uninterposed target) 
                eachLazyBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                                uintptr_t addr, uint8_t type, const char* symbolName,
                                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                                ExtraBindData *extraBindData,
                                                                const char* msg, LastLookup* last, bool runResolver) {
                        return ImageLoaderMachOCompressed::interposeAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                   addend, libraryOrdinal, extraBindData,
                                                                                                                   msg, last, runResolver);
                });

                // 2) non-lazy pointers in the dyld cache need to be interposed
                if ( ma->inDyldCache() ) {
                        eachBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                                uintptr_t addr, uint8_t type, const char* symbolName,
                                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                                ExtraBindData *extraBindData,
                                                                const char* msg, LastLookup* last, bool runResolver) {
                                return ImageLoaderMachOCompressed::interposeAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                           addend, libraryOrdinal, extraBindData,
                                                                                                                           msg, last, runResolver);
                        });
                }

        }
}


uintptr_t ImageLoaderMachOCompressed::dynamicInterposeAt(const LinkContext& context, ImageLoaderMachOCompressed* image,
                                                                                                                 uintptr_t addr, uint8_t type, const char* symbolName,
                                                         uint8_t, intptr_t, long,
                                                         ExtraBindData *extraBindData,
                                                         const char*, LastLookup*, bool runResolver)
{
        if ( type == BIND_TYPE_POINTER ) {
                uintptr_t* fixupLocation = (uintptr_t*)addr;
                uintptr_t value = *fixupLocation;
                // don't apply interposing to table entries.
                if ( (context.dynamicInterposeArray <= (void*)addr) && ((void*)addr < &context.dynamicInterposeArray[context.dynamicInterposeCount]) )
                        return 0;
                for(size_t i=0; i < context.dynamicInterposeCount; ++i) {
                        if ( value == (uintptr_t)context.dynamicInterposeArray[i].replacee ) {
                                if ( context.verboseInterposing ) {
                                        dyld::log("dyld: dynamic interposing: at %p replace %p with %p in %s\n", 
                                                fixupLocation, context.dynamicInterposeArray[i].replacee, context.dynamicInterposeArray[i].replacement, image->getPath());
                                }
                                *fixupLocation = (uintptr_t)context.dynamicInterposeArray[i].replacement;
                        }
                }
        }
        return 0;
}

void ImageLoaderMachOCompressed::dynamicInterpose(const LinkContext& context)
{
        if ( context.verboseInterposing )
                dyld::log("dyld: dynamic interposing %lu tuples onto image: %s\n", context.dynamicInterposeCount, this->getPath());

        // update already bound references to symbols
        eachBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                uintptr_t addr, uint8_t type, const char* symbolName,
                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                ExtraBindData *extraBindData,
                                                const char* msg, LastLookup* last, bool runResolver) {
                return ImageLoaderMachOCompressed::dynamicInterposeAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                          addend, libraryOrdinal, extraBindData,
                                                                                                                          msg, last, runResolver);
        });
        eachLazyBind(context, ^(const LinkContext& ctx, ImageLoaderMachOCompressed* image,
                                                        uintptr_t addr, uint8_t type, const char* symbolName,
                                                        uint8_t symbolFlags, intptr_t addend, long libraryOrdinal,
                                                        ExtraBindData *extraBindData,
                                                        const char* msg, LastLookup* last, bool runResolver) {
                return ImageLoaderMachOCompressed::dynamicInterposeAt(ctx, image, addr, type, symbolName, symbolFlags,
                                                                                                                          addend, libraryOrdinal, extraBindData,
                                                                                                                          msg, last, runResolver);
        });
}

const char* ImageLoaderMachOCompressed::findClosestSymbol(const void* addr, const void** closestAddr) const
{
        return ImageLoaderMachO::findClosestSymbol((mach_header*)fMachOData, addr, closestAddr);
}


#if PREBOUND_IMAGE_SUPPORT
void ImageLoaderMachOCompressed::resetPreboundLazyPointers(const LinkContext& context)
{
        // no way to back off a prebound compress image
}
#endif


#if __arm__ || __x86_64__
void ImageLoaderMachOCompressed::updateAlternateLazyPointer(uint8_t* stub, void** originalLazyPointerAddr, const LinkContext& context)
{
#if __arm__ 
        uint32_t* instructions = (uint32_t*)stub;
    // sanity check this is a stub we understand
        if ( (instructions[0] != 0xe59fc004) || (instructions[1] != 0xe08fc00c) || (instructions[2] != 0xe59cf000) )
                return;
    
        void** lazyPointerAddr = (void**)(instructions[3] + (stub + 12));
#endif
#if __x86_64__
    // sanity check this is a stub we understand
        if ( (stub[0] != 0xFF) || (stub[1] != 0x25) )
                return;
    int32_t ripOffset = *((int32_t*)(&stub[2]));
        void** lazyPointerAddr = (void**)(ripOffset + stub + 6);
#endif

   // if stub does not use original lazy pointer (meaning it was optimized by update_dyld_shared_cache)
    if ( lazyPointerAddr != originalLazyPointerAddr ) {
                // <rdar://problem/12928448> only de-optimization lazy pointers if they are part of shared cache not loaded (because overridden)
                const ImageLoader* lazyPointerImage = context.findImageContainingAddress(lazyPointerAddr);
                if ( lazyPointerImage != NULL )
                        return;
                
        // copy newly re-bound lazy pointer value to shared lazy pointer
        *lazyPointerAddr = *originalLazyPointerAddr;
                
                if ( context.verboseBind )
                        dyld::log("dyld: alter bind: %s: *0x%08lX = 0x%08lX \n",
                                          this->getShortName(), (long)lazyPointerAddr, (long)*originalLazyPointerAddr);
    }
}
#endif


// <rdar://problem/8890875> overriding shared cache dylibs with resolvers fails
void ImageLoaderMachOCompressed::updateOptimizedLazyPointers(const LinkContext& context)
{
#if __arm__ || __x86_64__
        // find stubs and indirect symbol table
        const struct macho_section* stubsSection = NULL;
        const dysymtab_command* dynSymbolTable = NULL;
        const macho_header* mh = (macho_header*)fMachOData;
        const uint32_t cmd_count = mh->ncmds;
        const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
        const struct load_command* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if (cmd->cmd == LC_SEGMENT_COMMAND) {
                        const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
                        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
                        const struct macho_section* const sectionsEnd = &sectionsStart[seg->nsects];
                        for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
                                const uint8_t type = sect->flags & SECTION_TYPE;
                                if ( type == S_SYMBOL_STUBS ) 
                                        stubsSection = sect;
                        }
                }
                else if ( cmd->cmd == LC_DYSYMTAB ) {
                        dynSymbolTable = (struct dysymtab_command*)cmd;
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }
        if ( dynSymbolTable == NULL )
                return;
        const uint32_t* const indirectTable = (uint32_t*)&fLinkEditBase[dynSymbolTable->indirectsymoff];
        if ( stubsSection == NULL )
                return;
        const uint32_t stubsSize = stubsSection->reserved2;
        const uint32_t stubsCount = (uint32_t)(stubsSection->size / stubsSize);
        const uint32_t stubsIndirectTableOffset = stubsSection->reserved1;
        if ( (stubsIndirectTableOffset+stubsCount) > dynSymbolTable->nindirectsyms )
                return;
        uint8_t* const stubsAddr = (uint8_t*)(stubsSection->addr + this->fSlide);

        // for each lazy pointer section
        cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if (cmd->cmd == LC_SEGMENT_COMMAND) {
                        const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
                        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
                        const struct macho_section* const sectionsEnd = &sectionsStart[seg->nsects];
                        for (const struct macho_section* lazyPointerSection=sectionsStart; lazyPointerSection < sectionsEnd; ++lazyPointerSection) {
                                const uint8_t type = lazyPointerSection->flags & SECTION_TYPE;
                                if ( type != S_LAZY_SYMBOL_POINTERS )
                                        continue;
                                const uint32_t lazyPointersCount = (uint32_t)(lazyPointerSection->size / sizeof(void*));
                                const uint32_t lazyPointersIndirectTableOffset = lazyPointerSection->reserved1;
                                if ( (lazyPointersIndirectTableOffset+lazyPointersCount) > dynSymbolTable->nindirectsyms )
                                        continue;
                                void** const lazyPointersAddr = (void**)(lazyPointerSection->addr + this->fSlide);
                                // for each lazy pointer
                                for(uint32_t lpIndex=0; lpIndex < lazyPointersCount; ++lpIndex) {
                                        const uint32_t lpSymbolIndex = indirectTable[lazyPointersIndirectTableOffset+lpIndex];
                                        // find matching stub and validate it uses this lazy pointer
                                        for(uint32_t stubIndex=0; stubIndex < stubsCount; ++stubIndex) {
                                                if ( indirectTable[stubsIndirectTableOffset+stubIndex] == lpSymbolIndex ) {
                                                        this->updateAlternateLazyPointer(stubsAddr+stubIndex*stubsSize, &lazyPointersAddr[lpIndex], context);
                                                        break;
                                                }
                                        }
                                }

                        }
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }

#endif
}


void ImageLoaderMachOCompressed::registerEncryption(const encryption_info_command* encryptCmd, const LinkContext& context)
{
#if (__arm__ || __arm64__) && !TARGET_OS_SIMULATOR
        if ( encryptCmd == NULL )
                return;
        // fMachOData not set up yet, need to manually find mach_header
        const mach_header* mh = NULL;
        for(unsigned int i=0; i < fSegmentsCount; ++i) {
                if ( (segFileOffset(i) == 0) && (segFileSize(i) != 0) ) {
                        mh = (mach_header*)segActualLoadAddress(i);
                        void* start = ((uint8_t*)mh) + encryptCmd->cryptoff;
                        size_t len = encryptCmd->cryptsize;
                        uint32_t cputype = mh->cputype;
                        uint32_t cpusubtype = mh->cpusubtype;
                        uint32_t cryptid = encryptCmd->cryptid;
                        if (context.verboseMapping) {
                                 dyld::log("                      0x%08lX->0x%08lX configured for FairPlay decryption\n", (long)start, (long)start+len);
                        }
                        int result = mremap_encrypted(start, len, cryptid, cputype, cpusubtype);
                        if ( result != 0 ) {
                                dyld::throwf("mremap_encrypted() => %d, errno=%d for %s\n", result, errno, this->getPath());
                        }
                        return;
                }
        }
#endif
}