[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 "ImageLoaderMachOCompressed.h"
#include "mach-o/dyld_images.h"

#ifndef EXPORT_SYMBOL_FLAGS_KIND_ABSOLUTE
        #define EXPORT_SYMBOL_FLAGS_KIND_ABSOLUTE                       0x02
#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 __MAC_OS_X_VERSION_MIN_REQUIRED
                // <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 
                        image->setPath(path);

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

                // pre-fetch content of __DATA and __LINKEDIT segment for faster launches
                // don't do this on prebound images or if prefetching is disabled
        if ( !context.preFetchDisabled && !image->isPrebindable()) {
                        image->preFetchDATA(fd, offsetInFat, context);
                        image->markSequentialLINKEDIT(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);
                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)
{
}

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)));
        // re-export 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::markFreeLINKEDIT(const LinkContext& context)
{
        // mark that we are done with rebase and bind info 
        markLINKEDIT(context, MADV_FREE);
}

void ImageLoaderMachOCompressed::markSequentialLINKEDIT(const LinkContext& context)
{
        // mark the rebase and bind info and using sequential access
        markLINKEDIT(context, MADV_SEQUENTIAL);
}

void ImageLoaderMachOCompressed::markLINKEDIT(const LinkContext& context, int advise)
{
        // if not loaded at preferred address, mark rebase info 
        uintptr_t start = 0;
        if ( (fSlide != 0) && (fDyldInfo->rebase_size != 0) ) 
                start = (uintptr_t)fLinkEditBase + fDyldInfo->rebase_off;
        else if ( fDyldInfo->bind_off != 0 )
                start = (uintptr_t)fLinkEditBase + fDyldInfo->bind_off;
        else
                return; // no binding info to prefetch
                
        // end is at end of bind info
        uintptr_t end = 0;
        if ( fDyldInfo->bind_off != 0 )
                end = (uintptr_t)fLinkEditBase + fDyldInfo->bind_off + fDyldInfo->bind_size;
        else if ( fDyldInfo->rebase_off != 0 )
                end = (uintptr_t)fLinkEditBase + fDyldInfo->rebase_off + fDyldInfo->rebase_size;
        else
                return;
                
                        
        // round to whole pages
        start = dyld_page_trunc(start);
        end = dyld_page_round(end);

        // do nothing if only one page of rebase/bind info
        if ( (end-start) <= dyld_page_size )
                return;
        
        // tell kernel about our access to these pages
        madvise((void*)start, end-start, advise);
        if ( context.verboseMapping ) {
                const char* adstr = "sequential";
                if ( advise == MADV_FREE )
                        adstr = "free";
                dyld::log("%18s %s 0x%0lX -> 0x%0lX for %s\n", "__LINKEDIT", adstr, start, end-1, this->getPath());
        }
}



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)
{
        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;

        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);
                        }
                }
        }
        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());
        if ( fDyldInfo->export_size == 0 )
                return NULL;
#if LOG_BINDINGS
        dyld::logBindings("%s: %s\n", this->getShortName(), symbol);
#endif
        ++ImageLoaderMachO::fgSymbolTrieSearchs;
        const uint8_t* start = &fLinkEditBase[fDyldInfo->export_off];
        const uint8_t* end = &start[fDyldInfo->export_size];
        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);
                                //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
{
        const uint8_t* start = &fLinkEditBase[fDyldInfo->export_off];
        const uint8_t* end = &start[fDyldInfo->export_size];
        return ( (start <= addr) && (addr < end) );
}


uintptr_t ImageLoaderMachOCompressed::exportedSymbolAddress(const LinkContext& context, const Symbol* symbol, const ImageLoader* requestor, bool runResolver) const
{
        const uint8_t* exportNode = (uint8_t*)symbol;
        const uint8_t* exportTrieStart = fLinkEditBase + fDyldInfo->export_off;
        const uint8_t* exportTrieEnd = exportTrieStart + fDyldInfo->export_size;
        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);
                                uintptr_t result = (*resolver)();
                                if ( context.verboseBind )
                                        dyld::log("dyld: resolver at %p returned 0x%08lX\n", resolver, result);
                                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
{
        const uint8_t* exportNode = (uint8_t*)symbol;
        const uint8_t* exportTrieStart = fLinkEditBase + fDyldInfo->export_off;
        const uint8_t* exportTrieEnd = exportTrieStart + fDyldInfo->export_size;
        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");
}


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 __MAC_OS_X_VERSION_MIN_REQUIRED
                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,
                                                                                                        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_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 {
                                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, uintptr_t addr, uint8_t type, const char* symbolName, 
                                                                uint8_t symbolFlags, intptr_t addend, long libraryOrdinal, const char* msg,
                                                                LastLookup* last, bool runResolver)
{
        const ImageLoader*      targetImage;
        uintptr_t                       symbolAddress;
        
        // resolve symbol
        symbolAddress = this->resolve(context, symbolName, symbolFlags, libraryOrdinal, &targetImage, last, runResolver);

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


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)
{
        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
        }
        else {
                uint64_t t0 = mach_absolute_time();

        #if TEXT_RELOC_SUPPORT
                // if there are __TEXT fixups, temporarily make __TEXT writable
                if ( fTextSegmentBinds ) 
                        this->makeTextSegmentWritable(context, true);
        #endif
        
                // run through all binding opcodes
                eachBind(context, &ImageLoaderMachOCompressed::bindAt);
                        
        #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);
            
                // 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);
        
                // tell kernel we are done with chunks of LINKEDIT
                if ( !context.preFetchDisabled ) 
                        this->markFreeLINKEDIT(context);

                uint64_t t1 = mach_absolute_time();
                ImageLoader::fgTotalRebindCacheTime += (t1-t0);
        }
        
        // 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)
{
        eachLazyBind(context, &ImageLoaderMachOCompressed::bindAt);
}

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;
                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 ( (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*");
                                        (this->*handler)(context, address, type, symbolName, symboFlags, addend, libraryOrdinal, "", &last, false);
                                        address += sizeof(intptr_t);
                                        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*");
                                        (this->*handler)(context, address, type, symbolName, symboFlags, addend, libraryOrdinal, "", &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*");
                                        (this->*handler)(context, address, type, symbolName, symboFlags, addend, libraryOrdinal, "", &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);
                                                (this->*handler)(context, address, type, symbolName, symboFlags, addend, libraryOrdinal, "", &last, false);
                                                address += skip + sizeof(intptr_t);
                                        }
                                        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");
                                        (this->*handler)(context, address, type, symbolName, symboFlags, addend, libraryOrdinal, "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)
{
        // 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, ptrToBind, BIND_TYPE_POINTER, symbolName, 0, 0, libraryOrdinal, "lazy ", 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();
        }
        
        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 = this->bindAt(context, address, BIND_TYPE_POINTER, symbolName, 0, 0, libraryOrdinal, "lazy ", 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->weak_bind_size;
        it.address = 0;
        it.type = 0;
        it.addend = 0;
}


bool ImageLoaderMachOCompressed::incrementCoalIterator(CoalIterator& it)
{
        if ( it.done )
                return false;
                
        if ( 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;

        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, address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ");
                                boundSomething = true;
                                address += sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
                                bindLocation(context, address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ");
                                boundSomething = true;
                                address += read_uleb128(p, end) + sizeof(intptr_t);
                                break;
                        case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
                                bindLocation(context, address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ");
                                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, address, value, type, symbolName, addend, this->getPath(), targetImage ? targetImage->getPath() : NULL, "weak ");
                                        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, uintptr_t addr, uint8_t type, const char*, 
                                                                                                uint8_t, intptr_t, long, 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, this);
                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());

        // update prebound symbols
        eachBind(context, &ImageLoaderMachOCompressed::interposeAt);
        eachLazyBind(context, &ImageLoaderMachOCompressed::interposeAt);
}


uintptr_t ImageLoaderMachOCompressed::dynamicInterposeAt(const LinkContext& context, uintptr_t addr, uint8_t type, const char* symbolName, 
                                                                                                uint8_t, intptr_t, long, 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, this->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, &ImageLoaderMachOCompressed::dynamicInterposeAt);
        eachLazyBind(context, &ImageLoaderMachOCompressed::dynamicInterposeAt);
}

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__
        if ( encryptCmd == NULL )
                return;
        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);
                        break;
                }
        }
        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());
        }
#endif
}