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

/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
 *
 * Copyright (c) 2004-2005 Apple Computer, 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@
 */

#define __STDC_LIMIT_MACROS
#include <stdint.h>
#include <errno.h>
#include <fcntl.h>
#include <mach/mach.h>
#include <mach-o/fat.h> 
#include <sys/types.h>
#include <sys/stat.h> 
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/mount.h>

#include "ImageLoader.h"


uint32_t                                                                ImageLoader::fgImagesWithUsedPrebinding = 0;
uint32_t                                                                ImageLoader::fgTotalRebaseFixups = 0;
uint32_t                                                                ImageLoader::fgTotalBindFixups = 0;
uint32_t                                                                ImageLoader::fgTotalLazyBindFixups = 0;
uint32_t                                                                ImageLoader::fgTotalPossibleLazyBindFixups = 0;
uint64_t                                                                ImageLoader::fgTotalLoadLibrariesTime;
uint64_t                                                                ImageLoader::fgTotalRebaseTime;
uint64_t                                                                ImageLoader::fgTotalBindTime;
uint64_t                                                                ImageLoader::fgTotalNotifyTime;
uint64_t                                                                ImageLoader::fgTotalInitTime;
uintptr_t                                                               ImageLoader::fgNextSplitSegAddress = 0x90000000;
uintptr_t                                                               Segment::fgNextNonSplitSegAddress = 0x8F000000;



__attribute__((noreturn))
void throwf(const char* format, ...) 
{
        va_list list;
        char*   p;
        va_start(list, format);
        vasprintf(&p, format, list);
        va_end(list);
        
        const char*     t = p;
        throw t;
}

void ImageLoader::init(const char* path, uint64_t offsetInFat, dev_t device, ino_t inode, time_t modDate)
{
        fPathHash = 0;
        fPath = NULL;
        if ( path != NULL )
                this->setPath(path);
        fLogicalPath = NULL;
        fDevice = device;
        fInode = inode;
        fLastModified = modDate;
        fOffsetInFatFile = offsetInFat;
        //fSegments = NULL;
        fLibraries = NULL;
        fLibrariesCount = 0;
        fReferenceCount = 0;
        fAllLibraryChecksumsAndLoadAddressesMatch = false;
        fLeaveMapped = false;
        fHideSymbols = false;
        fMatchByInstallName = false;
        fLibrariesLoaded = false;
        fBased = false;
        fBoundAllNonLazy = false;
        fBoundAllLazy = false;
        fAnnounced = false;
        fInitialized = false;
        fNextAddImageIndex = 0;
}


ImageLoader::ImageLoader(const char* path, uint64_t offsetInFat, const struct stat& info)
{
        init(path, offsetInFat, info.st_dev, info.st_ino, info.st_mtime);
}

ImageLoader::ImageLoader(const char* moduleName)
{
        init(moduleName, 0, 0, 0, 0);
}


ImageLoader::~ImageLoader()
{
        // need to read up on STL and see if this is right way to destruct vector contents
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                delete seg;
        }
        if ( fPath != NULL ) 
                delete [] fPath;
        if ( fLogicalPath != NULL ) 
                delete [] fLogicalPath;
}

                        
void ImageLoader::setPath(const char* path)
{
        if ( fPath != NULL ) {
                // if duplicate path, do nothing
                if ( strcmp(path, fPath) == 0 )
                        return;
                delete [] fPath;
        }
        fPath = new char[strlen(path)+1];
        strcpy((char*)fPath, path);
        fPathHash = hash(fPath);
}

void ImageLoader::setLogicalPath(const char* path)
{
        if ( fPath == NULL ) {
                // no physical path set yet, so use this path as physical
                this->setPath(path);
        }
        else if ( strcmp(path, fPath) == 0 ) {
                // do not set logical path because it is the same as the physical path
                fLogicalPath = NULL;
        }
        else {
                fLogicalPath = new char[strlen(path)+1];
                strcpy((char*)fLogicalPath, path);
        }
}

const char* ImageLoader::getLogicalPath() const
{
        if ( fLogicalPath != NULL )
                return fLogicalPath;
        else
                return fPath;
}

uint32_t ImageLoader::hash(const char* path)
{
        // this does not need to be a great hash
        // it is just used to reduce the number of strcmp() calls
        // of existing images when loading a new image
        uint32_t h = 0;
        for (const char* s=path; *s != '\0'; ++s)
                h = h*5 + *s;
        return h;
}

bool ImageLoader::matchInstallPath() const
{
        return fMatchByInstallName;
}

void ImageLoader::setMatchInstallPath(bool match)
{
        fMatchByInstallName = match;
}

bool ImageLoader::statMatch(const struct stat& stat_buf) const
{
        return ( (this->fDevice == stat_buf.st_dev) && (this->fInode == stat_buf.st_ino) );     
}

const char* ImageLoader::getShortName() const
{
        // try to return leaf name
        if ( fPath != NULL ) {
                const char* s = strrchr(fPath, '/');
                if ( s != NULL ) 
                        return &s[1];
        }
        return fPath; 
}

uint64_t ImageLoader::getOffsetInFatFile() const
{
        return fOffsetInFatFile;
}

void ImageLoader::setLeaveMapped()
{
        fLeaveMapped = true;
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                fSegments[i]->setUnMapWhenDestructed(false);
        }
}

void ImageLoader::setHideExports(bool hide)
{
        fHideSymbols = hide;
}

bool ImageLoader::hasHiddenExports() const
{
        return fHideSymbols;
}

bool ImageLoader::isLinked() const
{
        return fBoundAllNonLazy;
}

time_t ImageLoader::lastModified()
{
        return fLastModified;
}

bool ImageLoader::containsAddress(const void* addr) const
{
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                const uint8_t* start = (const uint8_t*)seg->getActualLoadAddress();
                const uint8_t* end = start + seg->getSize();
                if ( (start <= addr) && (addr < end) && !seg->unaccessible() )
                        return true;
        }
        return false;
}

void ImageLoader::addMappedRegions(RegionsVector& regions) const
{
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                MappedRegion region;
                region.address = seg->getActualLoadAddress();
                region.size = seg->getSize();
                regions.push_back(region);
        }
}


void ImageLoader::incrementReferenceCount()
{
        ++fReferenceCount;
}

bool ImageLoader::decrementReferenceCount()
{
        return ( --fReferenceCount == 0 );
}

// private method that handles circular dependencies by only search any image once
const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImagesExcept(const char* name, std::set<const ImageLoader*>& dontSearchImages, ImageLoader** foundIn) const
{
        const ImageLoader::Symbol* sym;
        // search self
        if ( dontSearchImages.count(this) == 0 ) {
                sym = this->findExportedSymbol(name, NULL, false, foundIn);
                if ( sym != NULL )
                        return sym;
                dontSearchImages.insert(this);
        }

        // search directly dependent libraries
        for (uint32_t i=0; i < fLibrariesCount; ++i) {
                ImageLoader* dependentImage = fLibraries[i].image;
                if ( (dependentImage != NULL) && (dontSearchImages.count(dependentImage) == 0) ) {
                        const ImageLoader::Symbol* sym = dependentImage->findExportedSymbol(name, NULL, false, foundIn);
                        if ( sym != NULL )
                                return sym;
                }
        }
        
        // search indirectly dependent libraries
        for (uint32_t i=0; i < fLibrariesCount; ++i) {
                ImageLoader* dependentImage = fLibraries[i].image;
                if ( (dependentImage != NULL) && (dontSearchImages.count(dependentImage) == 0) ) {
                        const ImageLoader::Symbol* sym = dependentImage->findExportedSymbolInDependentImagesExcept(name, dontSearchImages, foundIn);
                        if ( sym != NULL )
                                return sym;
                        dontSearchImages.insert(dependentImage);
                }
        }

        return NULL;
}


const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImages(const char* name, ImageLoader** foundIn) const
{
        std::set<const ImageLoader*> dontSearchImages;
        dontSearchImages.insert(this);  // don't search this image
        return this->findExportedSymbolInDependentImagesExcept(name, dontSearchImages, foundIn);
}

const ImageLoader::Symbol* ImageLoader::findExportedSymbolInImageOrDependentImages(const char* name, ImageLoader** foundIn) const
{
        std::set<const ImageLoader*> dontSearchImages;
        return this->findExportedSymbolInDependentImagesExcept(name, dontSearchImages, foundIn);
}


void ImageLoader::link(const LinkContext& context, BindingLaziness bindness, InitializerRunning inits, uint32_t notifyCount)
{
        uint64_t t1 = mach_absolute_time();
        this->recursiveLoadLibraries(context);
        
        uint64_t t2 = mach_absolute_time();
        this->recursiveRebase(context);
        
        uint64_t t3 = mach_absolute_time();
        this->recursiveBind(context, bindness);
        
        uint64_t t4 = mach_absolute_time();     
        this->recursiveImageNotification(context, notifyCount); 
        
        if ( (inits == kRunInitializers) || (inits == kDontRunInitializersButTellObjc) ) {
                std::vector<ImageLoader*>       newImages;
                this->recursiveImageAnnouncement(context, newImages);    // build bottom up list images being added
                context.notifyAdding(newImages);        // tell gdb or anyone who cares about these
        }
        
        uint64_t t5 = mach_absolute_time();
        if ( inits == kRunInitializers ) {
                this->recursiveInitialization(context);
                uint64_t t6 = mach_absolute_time();
                fgTotalInitTime += t6 - t5;
        }
        fgTotalLoadLibrariesTime += t2 - t1;
        fgTotalRebaseTime += t3 - t2;
        fgTotalBindTime += t4 - t3;
        fgTotalNotifyTime += t5 - t4;
}


// only called pre-main on main executable
// if crt.c is ever cleaned up, this could go away
void ImageLoader::runInitializers(const LinkContext& context)
{
                std::vector<ImageLoader*>       newImages;
                this->recursiveImageAnnouncement(context, newImages);    // build bottom up list images being added
                context.notifyAdding(newImages);        // tell gdb or anyone who cares about these

        this->recursiveInitialization(context);
}

// called inside _dyld_register_func_for_add_image()
void ImageLoader::runNotification(const LinkContext& context, uint32_t notifyCount)
{
        this->recursiveImageNotification(context, notifyCount);
}


intptr_t ImageLoader::assignSegmentAddresses(const LinkContext& context)
{
        // preflight and calculate slide if needed
        const unsigned int segmentCount = fSegments.size();
        intptr_t slide = 0;
        if ( this->segmentsCanSlide() && this->segmentsMustSlideTogether() ) {
                bool needsToSlide = false;
                uintptr_t lowAddr = UINTPTR_MAX;
                uintptr_t highAddr = 0;
                for(unsigned int i=0; i < segmentCount; ++i){
                        Segment* seg = fSegments[i];
                        const uintptr_t segLow = seg->getPreferredLoadAddress();
                        const uintptr_t segHigh = segLow + seg->getSize();
                        if ( segLow < lowAddr )
                                lowAddr = segLow;
                        if ( segHigh > highAddr )
                                highAddr = segHigh;
                                
                        if ( context.slideAndPackDylibs || !seg->hasPreferredLoadAddress() || !Segment::reserveAddressRange(seg->getPreferredLoadAddress(), seg->getSize()) )
                                needsToSlide = true;
                }
                if ( needsToSlide ) {
                        // find a chunk of address space to hold all segments
                        uintptr_t addr = Segment::reserveAnAddressRange(highAddr-lowAddr, context);
                        slide = addr - lowAddr;
                }
        } 
        else if ( ! this->segmentsCanSlide() ) {
                for(unsigned int i=0; i < segmentCount; ++i){
                        Segment* seg = fSegments[i];
                        if ( strcmp(seg->getName(), "__PAGEZERO") == 0 )
                                continue;
                        if ( !Segment::reserveAddressRange(seg->getPreferredLoadAddress(), seg->getSize()) )
                                throw "can't map";
                }
        }
        else {
                // mach-o does not support independently sliding segments
        }
        return slide;
}


void ImageLoader::mapSegments(int fd, uint64_t offsetInFat, uint64_t lenInFat, uint64_t fileLen, const LinkContext& context)
{
        if ( context.verboseMapping )
                fprintf(stderr, "dyld: Mapping %s\n", this->getPath());
        // find address range for image
        intptr_t slide = this->assignSegmentAddresses(context);
        // map in all segments
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                seg->map(fd, offsetInFat, slide, context);              
        }
        // update slide to reflect load location                        
        this->setSlide(slide);
        
        // now that it is mapped and slide is set, mark that we should unmap it when done
        for(unsigned int i=0; i < segmentCount; ++i){
                fSegments[i]->setUnMapWhenDestructed(true);
        }
}

void ImageLoader::mapSegments(const void* memoryImage, uint64_t imageLen, const LinkContext& context)
{
        if ( context.verboseMapping )
                fprintf(stderr, "dyld: Mapping memory %p\n", memoryImage);
        // find address range for image
        intptr_t slide = this->assignSegmentAddresses(context);
        // map in all segments
        const unsigned int segmentCount = fSegments.size();
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                seg->map(memoryImage, slide, context);          
        }
        // update slide to reflect load location                        
        this->setSlide(slide);
        // set R/W permissions on all segments at slide location
        for(unsigned int i=0; i < segmentCount; ++i){
                Segment* seg = fSegments[i];
                seg->setPermissions();          
        }
}

bool ImageLoader::allDependentLibrariesAsWhenPreBound() const
{
        return fAllLibraryChecksumsAndLoadAddressesMatch;
}


void ImageLoader::recursiveLoadLibraries(const LinkContext& context)
{
        if ( ! fLibrariesLoaded ) {
                // break cycles
                fLibrariesLoaded = true;
                
                // get list of libraries this image needs
                fLibrariesCount = this->doGetDependentLibraryCount();
                fLibraries = new DependentLibrary[fLibrariesCount];
                this->doGetDependentLibraries(fLibraries);
                
                // try to load each
                bool canUsePrelinkingInfo = true; 
                for(unsigned int i=0; i < fLibrariesCount; ++i){
                        DependentLibrary& requiredLib = fLibraries[i];
                        try {
                                requiredLib.image = context.loadLibrary(requiredLib.name, true, this->getPath(), NULL);
                                if ( requiredLib.image == this ) {
                                        // found circular reference, perhaps DYLD_LIBARY_PATH is causing this rdar://problem/3684168 
                                        requiredLib.image = context.loadLibrary(requiredLib.name, false, NULL, NULL);
                                        if ( requiredLib.image != this )
                                                fprintf(stderr, "dyld: warning DYLD_ setting caused circular dependency in %s\n", this->getPath());
                                }
                                LibraryInfo actualInfo = requiredLib.image->doGetLibraryInfo();
                                requiredLib.checksumMatches = ( actualInfo.checksum == requiredLib.info.checksum );
                                // check found library version is compatible
                                if ( actualInfo.minVersion < requiredLib.info.minVersion ) {
                                        throwf("Incompatible library version: %s requires version %d.%d.%d or later, but %s provides version %d.%d.%d",
                                                        this->getShortName(), requiredLib.info.minVersion >> 16, (requiredLib.info.minVersion >> 8) & 0xff, requiredLib.info.minVersion & 0xff,
                                                        requiredLib.image->getShortName(), actualInfo.minVersion >> 16, (actualInfo.minVersion >> 8) & 0xff, actualInfo.minVersion & 0xff);
                                }
                                // prebinding for this image disabled if any dependent library changed or slid
                                if ( !requiredLib.checksumMatches || (requiredLib.image->getSlide() != 0) )
                                        canUsePrelinkingInfo = false;
                                //if ( context.verbosePrebinding ) {
                                //      if ( !requiredLib.checksumMatches )
                                //              fprintf(stderr, "dyld: checksum mismatch, (%lld v %lld) for %s referencing %s\n", requiredLib.info.checksum, actualInfo.checksum, this->getPath(),      requiredLib.image->getPath());          
                                //      if ( requiredLib.image->getSlide() != 0 )
                                //              fprintf(stderr, "dyld: dependent library slid for %s referencing %s\n", this->getPath(), requiredLib.image->getPath());         
                                //}
                        }
                        catch (const char* msg) {
                                //if ( context.verbosePrebinding )
                                //      fprintf(stderr, "dyld: exception during processing for %s referencing %s\n", this->getPath(), requiredLib.image->getPath());            
                                if ( requiredLib.required ) {
                                        const char* formatString = "Library not loaded: %s\n  Referenced from: %s\n  Reason: %s";
                                        const char* referencedFrom = this->getPath();
                                        char buf[strlen(requiredLib.name)+strlen(referencedFrom)+strlen(formatString)+strlen(msg)+2];
                                        sprintf(buf, formatString, requiredLib.name, referencedFrom, msg);
                                        fLibrariesLoaded = false;
                                        throw strdup(buf);  // this is a leak if exception doesn't halt program
                                }
                                // ok if weak library not found
                                requiredLib.image = NULL;
                                canUsePrelinkingInfo = false;  // this disables all prebinding, we may want to just slam import vectors for this lib to zero
                        }
                }
                fAllLibraryChecksumsAndLoadAddressesMatch = canUsePrelinkingInfo;

                // tell each to load its dependents
                for(unsigned int i=0; i < fLibrariesCount; ++i){
                        DependentLibrary& libInfo = fLibraries[i];
                        if ( libInfo.image != NULL ) {  
                                libInfo.isSubFramework = libInfo.image->isSubframeworkOf(context, this);
                                libInfo.isReExported = libInfo.isSubFramework || this->hasSubLibrary(context, libInfo.image);
                                //if ( libInfo.isReExported  )
                                //      fprintf(stderr, "%s re-exports %s\n", strrchr(this->getPath(), '/'), strrchr(libInfo.image->getPath(),'/'));
                                libInfo.image->recursiveLoadLibraries(context);
                        }
                }
                
                // do deep prebind check
                if ( fAllLibraryChecksumsAndLoadAddressesMatch ) {
                        for(unsigned int i=0; i < fLibrariesCount; ++i){
                                const DependentLibrary& libInfo = fLibraries[i];
                                if ( libInfo.image != NULL ) {
                                        if ( !libInfo.image->allDependentLibrariesAsWhenPreBound() )
                                                fAllLibraryChecksumsAndLoadAddressesMatch = false;
                                }
                        }
                }
                
        }
}

void ImageLoader::recursiveRebase(const LinkContext& context)
{ 
        if ( ! fBased ) {
                // break cycles
                fBased = true;
                
                try {
                        // rebase lower level libraries first
                        for(unsigned int i=0; i < fLibrariesCount; ++i){
                                DependentLibrary& libInfo = fLibraries[i];
                                if ( libInfo.image != NULL )
                                        libInfo.image->recursiveRebase(context);
                        }
                                
                        // rebase this image
                        doRebase(context);
                }
                catch (const char* msg) {
                        // this image is not rebased
                        fBased = false;
                        throw msg;
                }
        }
}




void ImageLoader::recursiveBind(const LinkContext& context, BindingLaziness bindness)
{
        // normally just non-lazy pointers are bound up front,
        // but DYLD_BIND_AT_LAUNCH will cause lazy pointers to be bound up from
        // and some dyld API's bind all lazys at runtime
        bool nonLazy = false;
        bool lazy = false;
        switch( bindness ) {
                case kNonLazyOnly:
                        nonLazy = true;
                        break;
                case kLazyAndNonLazy:
                        nonLazy = true;
                        lazy = true;
                        break;
                case kLazyOnly:
                case kLazyOnlyNoDependents:
                        lazy = true;
                        break;
        }
        const bool doNonLazy = nonLazy && !fBoundAllNonLazy;
        const bool doLazy = lazy && !fBoundAllLazy;
        if ( doNonLazy || doLazy ) {
                // break cycles
                bool oldBoundAllNonLazy = fBoundAllNonLazy;
                bool oldBoundAllLazy = fBoundAllLazy;
                fBoundAllNonLazy = fBoundAllNonLazy || nonLazy;
                fBoundAllLazy = fBoundAllLazy || lazy;
                
                try {
                        // bind lower level libraries first
                        if ( bindness != kLazyOnlyNoDependents ) {
                                for(unsigned int i=0; i < fLibrariesCount; ++i){
                                        DependentLibrary& libInfo = fLibraries[i];
                                        if ( libInfo.image != NULL )
                                                libInfo.image->recursiveBind(context, bindness);
                                }
                        }
                        // bind this image
                        if ( doLazy && !doNonLazy )
                                doBind(context, kLazyOnly);     
                        else if ( !doLazy && doNonLazy )
                                doBind(context, kNonLazyOnly);
                        else 
                                doBind(context, kLazyAndNonLazy);
                }
                catch (const char* msg) {
                        // restore state
                        fBoundAllNonLazy = oldBoundAllNonLazy;
                        fBoundAllLazy = oldBoundAllLazy;
                        throw msg;
                }
        }
}

//
// This is complex because _dyld_register_func_for_add_image() is defined to not only
// notify you of future image loads, but also of all currently loaded images.  Therefore
// each image needs to track that all add-image-funcs have been notified about it.
// Since add-image-funcs cannot be removed, each has a unique index and each image
// records the thru which index notificiation has already been done.
//
void ImageLoader::recursiveImageNotification(const LinkContext& context, uint32_t addImageCount)
{
        if ( fNextAddImageIndex < addImageCount ) {
                // break cycles
                const uint32_t initIndex = fNextAddImageIndex;
                fNextAddImageIndex = addImageCount;
        
                // notify all requestors about this image
                context.imageNotification(this, initIndex);
        
                // notify about lower level libraries first
                for(unsigned int i=0; i < fLibrariesCount; ++i){
                        DependentLibrary& libInfo = fLibraries[i];
                        if ( libInfo.image != NULL )
                                libInfo.image->recursiveImageNotification(context, addImageCount);
                }
        }
}


void ImageLoader::recursiveImageAnnouncement(const LinkContext& context, std::vector<ImageLoader*>& newImages)
{
        if ( ! fAnnounced ) {
                // break cycles
                fAnnounced = true;
                
                // announce lower level libraries first
                for(unsigned int i=0; i < fLibrariesCount; ++i){
                        DependentLibrary& libInfo = fLibraries[i];
                        if ( libInfo.image != NULL )
                                libInfo.image->recursiveImageAnnouncement(context, newImages);
                }
                
                // add to list of images to notify gdb about
                newImages.push_back(this);
                //fprintf(stderr, "next size = %d\n", newImages.size());
                
                // remember that this image wants to be notified about other images
                 if ( this->hasImageNotification() )
                        context.addImageNeedingNotification(this);
        }
}



void ImageLoader::recursiveInitialization(const LinkContext& context)
{
        if ( ! fInitialized ) {
                // break cycles
                fInitialized = true;

                try {
                        // initialize lower level libraries first
                        for(unsigned int i=0; i < fLibrariesCount; ++i){
                                DependentLibrary& libInfo = fLibraries[i];
                                if ( libInfo.image != NULL )
                                        libInfo.image->recursiveInitialization(context);
                        }
                        
                        // record termination order
                        if ( this->needsTermination() )
                                context.terminationRecorder(this);
                        
                        // initialize this image
                        this->doInitialization(context);
                }
                catch (const char* msg) {
                        // this image is not initialized
                        fInitialized = false;
                        throw msg;
                }
        }
}

void ImageLoader::reprebindCommit(const LinkContext& context, bool commit, bool unmapOld)
{
        // do nothing on unprebound images
        if ( ! this->isPrebindable() )
                return;

        // do nothing if prebinding is up to date
        if ( this->usablePrebinding(context) )
                return;
                
        // make sure we are not replacing a symlink with a file
        char realFilePath[PATH_MAX];
        if ( realpath(this->getPath(), realFilePath) == NULL ) {
                throwf("realpath() failed on %s, errno=%d", this->getPath(), errno);
        }
        // recreate temp file name
        char tempFilePath[PATH_MAX];
        char suffix[64];
        sprintf(suffix, "_redoprebinding%d", getpid());
        ImageLoader::addSuffix(realFilePath, suffix, tempFilePath);

        if ( commit ) {
                // all files successfully reprebound, so do swap
                int result = rename(tempFilePath, realFilePath);
                if ( result != 0 ) {
                        // if there are two dylibs with the same install path, the second will fail to prebind
                        // because the _redoprebinding temp file is gone.  In that case, log and go on.
                        if ( errno == ENOENT )
                                fprintf(stderr, "update_prebinding: temp file missing: %s\n", tempFilePath);
                        else
                                throwf("can't swap temporary re-prebound file: rename(%s,%s) returned errno=%d", tempFilePath, realFilePath, errno);
                }
                else if ( unmapOld ) {
                        this->prebindUnmap(context);
                }
        }
        else {
                // something went wrong during prebinding, delete the temp files
                unlink(tempFilePath);
        }
}

uint64_t ImageLoader::reprebind(const LinkContext& context, time_t timestamp)
{
        // do nothing on unprebound images
        if ( ! this->isPrebindable() )
                return INT64_MAX;

        // do nothing if prebinding is up to date
        if ( this->usablePrebinding(context) ) {
                if ( context.verbosePrebinding )
                        fprintf(stderr, "dyld: no need to re-prebind: %s\n", this->getPath());
                return INT64_MAX;
        }
        // recreate temp file name
        char realFilePath[PATH_MAX];
        if ( realpath(this->getPath(), realFilePath) == NULL ) {
                throwf("realpath() failed on %s, errno=%d", this->getPath(), errno);
        }
        char tempFilePath[PATH_MAX];
        char suffix[64];
        sprintf(suffix, "_redoprebinding%d", getpid());
        ImageLoader::addSuffix(realFilePath, suffix, tempFilePath);

        // make copy of file and map it in
        uint8_t* fileToPrebind;
        uint64_t fileToPrebindSize;
        uint64_t freespace = this->copyAndMap(tempFilePath, &fileToPrebind, &fileToPrebindSize);

        // do format specific prebinding
        this->doPrebinding(context, timestamp, fileToPrebind);
        
        // flush and swap files
        int result = msync(fileToPrebind, fileToPrebindSize, MS_ASYNC);
        if ( result != 0 )
                throw "error syncing re-prebound file";
        result = munmap(fileToPrebind, fileToPrebindSize);
        if ( result != 0 )
                throw "error unmapping re-prebound file";

        // log
        if ( context.verbosePrebinding )
                fprintf(stderr, "dyld: re-prebound: %p %s\n", this->machHeader(), this->getPath());
        
        return freespace;
}

uint64_t ImageLoader::copyAndMap(const char* tempFile, uint8_t** fileToPrebind, uint64_t* fileToPrebindSize) 
{
        // reopen dylib 
        int src = open(this->getPath(), O_RDONLY);      
        if ( src == -1 )
                throw "can't open image";
        struct stat stat_buf;
        if ( fstat(src, &stat_buf) == -1)
                throw "can't stat image";
        if ( stat_buf.st_mtime != fLastModified )
                throw "image file changed since it was loaded";
                
        // create new file with all same permissions to hold copy of dylib 
        unlink(tempFile);
        int dst = open(tempFile, O_CREAT | O_RDWR | O_TRUNC, stat_buf.st_mode); 
        if ( dst == -1 )
                throw "can't create temp image";

        // mark source as "don't cache"
        (void)fcntl(src, F_NOCACHE, 1);
        // we want to cache the dst because we are about to map it in and modify it
        
        // copy permission bits
        if ( chmod(tempFile, stat_buf.st_mode & 07777) == -1 )
                throwf("can't chmod temp image.  errno=%d for %s", errno, this->getPath());
        if ( chown(tempFile, stat_buf.st_uid, stat_buf.st_gid) == -1)
                throwf("can't chown temp image.  errno=%d for %s", errno, this->getPath());
                  
        // copy contents
        ssize_t len;
        const uint32_t kBufferSize = 128*1024;
        static uint8_t* buffer = NULL;
        if ( buffer == NULL ) {
                vm_address_t addr = 0;
                if ( vm_allocate(mach_task_self(), &addr, kBufferSize, true /*find range*/) == KERN_SUCCESS )
                        buffer = (uint8_t*)addr;
                else
                        throw "can't allcoate copy buffer";
        }
        while ( (len = read(src, buffer, kBufferSize)) > 0 ) {
                if ( write(dst, buffer, len) == -1 )
                        throwf("write failure copying dylib errno=%d for %s", errno, this->getPath());
        }
        
        // map in dst file
        *fileToPrebindSize = stat_buf.st_size - fOffsetInFatFile; // this may map in too much, but it does not matter
        *fileToPrebind = (uint8_t*)mmap(NULL, *fileToPrebindSize, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, dst, fOffsetInFatFile);
        if ( *fileToPrebind == (uint8_t*)(-1) )
                throw "can't mmap temp image";
                
        // get free space remaining on dst volume
        struct statfs statfs_buf;
        if ( fstatfs(dst, &statfs_buf) != 0 )
                throwf("can't fstatfs(), errno=%d for %s", errno, tempFile);
        uint64_t freespace = (uint64_t)statfs_buf.f_bavail * (uint64_t)statfs_buf.f_bsize;
        
        // closing notes:  
        //              ok to close file after mapped in
        //              ok to throw above without closing file because the throw will terminate update_prebinding
        int result1 = close(dst);
        int result2 = close(src);
        if ( (result1 != 0) || (result2 != 0) )
                throw "can't close file";
                
        return freespace;
}


static void printTime(const char* msg, uint64_t partTime, uint64_t totalTime)
{
        static uint64_t sUnitsPerSecond = 0;
        if ( sUnitsPerSecond == 0 ) {
                struct mach_timebase_info timeBaseInfo;
                if ( mach_timebase_info(&timeBaseInfo) == KERN_SUCCESS ) {
                        sUnitsPerSecond = 1000000000ULL * timeBaseInfo.denom / timeBaseInfo.numer;
                }
        }
        if ( partTime < sUnitsPerSecond ) {
                uint32_t milliSecondsTimeTen = (partTime*10000)/sUnitsPerSecond;
                uint32_t milliSeconds = milliSecondsTimeTen/10;
                uint32_t percentTimesTen = (partTime*1000)/totalTime;
                uint32_t percent = percentTimesTen/10;
                fprintf(stderr, "%s: %u.%u milliseconds (%u.%u%%)\n", msg, milliSeconds, milliSecondsTimeTen-milliSeconds*10, percent, percentTimesTen-percent*10);
        }
        else {
                uint32_t secondsTimeTen = (partTime*10)/sUnitsPerSecond;
                uint32_t seconds = secondsTimeTen/10;
                uint32_t percentTimesTen = (partTime*1000)/totalTime;
                uint32_t percent = percentTimesTen/10;
                fprintf(stderr, "%s: %u.%u seconds (%u.%u%%)\n", msg, seconds, secondsTimeTen-seconds*10, percent, percentTimesTen-percent*10);
        }
}

static char* commatize(uint64_t in, char* out)
{
        char* result = out;
        char rawNum[30];
        sprintf(rawNum, "%llu", in);
        const int rawNumLen = strlen(rawNum);
        for(int i=0; i < rawNumLen-1; ++i) {
                *out++ = rawNum[i];
                if ( ((rawNumLen-i) % 3) == 1 )
                        *out++ = ',';
        }
        *out++ = rawNum[rawNumLen-1];
        *out = '\0';
        return result;
} 


void ImageLoader::printStatistics(unsigned int imageCount)
{
        uint64_t totalTime = fgTotalLoadLibrariesTime + fgTotalRebaseTime + fgTotalBindTime + fgTotalNotifyTime + fgTotalInitTime;
        char commaNum1[40];
        char commaNum2[40];

        printTime("total time", totalTime, totalTime);
        fprintf(stderr, "total images loaded:  %d (%d used prebinding)\n", imageCount, fgImagesWithUsedPrebinding);
        printTime("total images loading time", fgTotalLoadLibrariesTime, totalTime);
        fprintf(stderr, "total rebase fixups:  %s\n", commatize(fgTotalRebaseFixups, commaNum1));
        printTime("total rebase fixups time", fgTotalRebaseTime, totalTime);
        fprintf(stderr, "total binding fixups: %s\n", commatize(fgTotalBindFixups, commaNum1));
        printTime("total binding fixups time", fgTotalBindTime, totalTime);
        fprintf(stderr, "total bindings lazily fixed up: %s of %s\n", commatize(fgTotalLazyBindFixups, commaNum1), commatize(fgTotalPossibleLazyBindFixups, commaNum2));
        printTime("total notify time time", fgTotalNotifyTime, totalTime);
        printTime("total init time time", fgTotalInitTime, totalTime);
}


//
// copy path and add suffix to result
//
//  /path/foo.dylib             _debug   =>   /path/foo_debug.dylib     
//  foo.dylib                   _debug   =>   foo_debug.dylib
//  foo                         _debug   =>   foo_debug
//  /path/bar                   _debug   =>   /path/bar_debug  
//  /path/bar.A.dylib   _debug   =>   /path/bar.A_debug.dylib
//
void ImageLoader::addSuffix(const char* path, const char* suffix, char* result)
{
        strcpy(result, path);
        
        char* start = strrchr(result, '/');
        if ( start != NULL )
                start++;
        else
                start = result;
                
        char* dot = strrchr(start, '.');
        if ( dot != NULL ) {
                strcpy(dot, suffix);
                strcat(&dot[strlen(suffix)], &path[dot-result]);
        }
        else {
                strcat(result, suffix);
        }
}


void Segment::map(int fd, uint64_t offsetInFatWrapper, intptr_t slide, const ImageLoader::LinkContext& context)
{
        vm_offset_t fileOffset = this->getFileOffset() + offsetInFatWrapper;
        vm_size_t size = this->getFileSize();
        void* requestedLoadAddress = (void*)(this->getPreferredLoadAddress() + slide);
        int protection = 0;
        if ( !this->unaccessible() ) {
                if ( this->executable() )
                        protection   |= PROT_EXEC;
                if ( this->readable() )
                        protection   |= PROT_READ;
                if ( this->writeable() )
                        protection   |= PROT_WRITE;
        }
        void* loadAddress = mmap(requestedLoadAddress, size, protection, MAP_FILE | MAP_FIXED | MAP_PRIVATE, fd, fileOffset);
        if ( loadAddress == ((void*)(-1)) )
                throwf("mmap() error %d at address=0x%08lX, size=0x%08lX in Segment::map() mapping %s", errno, (uintptr_t)requestedLoadAddress, (uintptr_t)size, this->getImage()->getPath());
        
        if ( context.verboseMapping )
                fprintf(stderr, "%18s at %p->%p\n", this->getName(), loadAddress, (char*)loadAddress+this->getFileSize()-1);
}

void Segment::map(const void* memoryImage, intptr_t slide, const ImageLoader::LinkContext& context)
{
        vm_address_t loadAddress = this->getPreferredLoadAddress() + slide;
        vm_address_t srcAddr = (uintptr_t)memoryImage + this->getFileOffset();
        vm_size_t size = this->getFileSize();
        kern_return_t r = vm_copy(mach_task_self(), srcAddr, size, loadAddress);
        if ( r != KERN_SUCCESS ) 
                throw "can't map segment";
                
        if ( context.verboseMapping )
                fprintf(stderr, "%18s at %p->%p\n", this->getName(), (char*)loadAddress, (char*)loadAddress+this->getFileSize()-1);
}

void Segment::setPermissions()
{
        vm_prot_t protection = 0;
        if ( !this->unaccessible() ) {
                if ( this->executable() )
                        protection   |= VM_PROT_EXECUTE;
                if ( this->readable() )
                        protection   |= VM_PROT_READ;
                if ( this->writeable() )
                        protection   |= VM_PROT_WRITE;
        }
        vm_address_t addr = this->getActualLoadAddress();
        vm_size_t size = this->getSize();
        const bool setCurrentPermissions = false;
        kern_return_t r = vm_protect(mach_task_self(), addr, size, setCurrentPermissions, protection);
        if ( r != KERN_SUCCESS ) 
                throw "can't set vm permissions for mapped segment";
}       

void Segment::tempWritable()
{
        vm_address_t addr = this->getActualLoadAddress();
        vm_size_t size = this->getSize();
        const bool setCurrentPermissions = false;
        kern_return_t r = vm_protect(mach_task_self(), addr, size, setCurrentPermissions, VM_PROT_WRITE | VM_PROT_READ);
        if ( r != KERN_SUCCESS ) 
                throw "can't set vm permissions for mapped segment";
}


bool Segment::hasTrailingZeroFill()
{
        return ( this->writeable() && (this->getSize() > this->getFileSize()) );
}


uintptr_t Segment::reserveAnAddressRange(size_t length, const ImageLoader::LinkContext& context)
{
        vm_address_t addr = 0;
        vm_size_t size = length;
        if ( context.slideAndPackDylibs ) {
                addr = (fgNextNonSplitSegAddress - length) & (-4096); // page align
                kern_return_t r = vm_allocate(mach_task_self(), &addr, size, false /*use this range*/);
                if ( r != KERN_SUCCESS ) 
                        throw "out of address space";
                fgNextNonSplitSegAddress = addr;
        }
        else {
                kern_return_t r = vm_allocate(mach_task_self(), &addr, size, true /*find range*/);
                if ( r != KERN_SUCCESS ) 
                        throw "out of address space";
        }
        return addr;
}

bool Segment::reserveAddressRange(uintptr_t start, size_t length)
{
        vm_address_t addr = start;
        vm_size_t size = length;
        kern_return_t r = vm_allocate(mach_task_self(), &addr, size, false /*only this range*/);
        if ( r != KERN_SUCCESS ) 
                return false;
        return true;
}