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

/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
 *
 * Copyright (c) 2004-2009 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@
 */

//
// This file implements that API's in <mach-o/dyld.h>
//
//

#define __STDC_LIMIT_MACROS
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/param.h>
#include <sys/mount.h>
#include <Availability.h>


#include <vector>
#include <map>
#include <algorithm>

#include <mach/mach.h>
#include <sys/time.h>
#include <sys/sysctl.h>
#include <mach/mach_traps.h> // for task_self_trap()


#include "mach-o/dyld_images.h"
#include "mach-o/dyld.h"
#include "mach-o/dyld_priv.h"

#include "ImageLoader.h"
#include "ImageLoaderMachO.h"
#include "dyld.h"
#include "dyldLibSystemInterface.h"

#undef _POSIX_C_SOURCE
#include "dlfcn.h"

// from dyldExceptions.c
extern "C" void __Unwind_SjLj_SetThreadKey(pthread_key_t key);

// from dyld_gdb.cpp 
extern void addImagesToAllImages(uint32_t infoCount, const dyld_image_info info[]);
extern uint32_t allImagesCount();
extern const mach_header* allImagesIndexedMachHeader(uint32_t index);
extern const char* allImagesIndexedPath(uint32_t index);


// deprecated APIs are still availble on Mac OS X, but not on iPhone OS
#if __IPHONE_OS_VERSION_MIN_REQUIRED    
        #define DEPRECATED_APIS_SUPPORTED 0
#else
        #define DEPRECATED_APIS_SUPPORTED 1
#endif

static bool sDynamicInterposing = false;

#if DEPRECATED_APIS_SUPPORTED
static char sLastErrorFilePath[1024];
static NSLinkEditErrors sLastErrorFileCode;
static int sLastErrorNo;
#endif

// In 10.3.x and earlier all the NSObjectFileImage API's were implemeneted in libSystem.dylib
// Beginning in 10.4 the NSObjectFileImage API's are implemented in dyld and libSystem just forwards
// This conditional keeps support for old libSystem's which needed some help implementing the API's
#define OLD_LIBSYSTEM_SUPPORT (__i386__)

// The following functions have no prototype in any header.  They are special cases
// where _dyld_func_lookup() is used directly.
static void _dyld_make_delayed_module_initializer_calls();
static void registerThreadHelpers(const dyld::LibSystemHelpers*);
#if DEPRECATED_APIS_SUPPORTED
static void _dyld_install_handlers(void* undefined, void* multiple, void* linkEdit);
#if OLD_LIBSYSTEM_SUPPORT
static NSModule _dyld_link_module(NSObjectFileImage object_addr, size_t object_size, const char* moduleName, uint32_t options);
#endif
static void _dyld_register_binding_handler(void * (*)(const char *, const char *, void *), ImageLoader::BindingOptions);
static bool NSMakePrivateModulePublic(NSModule module);
static void _dyld_call_module_initializers_for_dylib(const struct mach_header* mh_dylib_header);

// The following functions are dyld API's, but since dyld links with a static copy of libc.a
// the public name cannot be used.
static void             client_dyld_lookup_and_bind(const char* symbolName, void** address, NSModule* module);
static bool             client_NSIsSymbolNameDefined(const char* symbolName);
#endif // DEPRECATED_APIS_SUPPORTED
#if SUPPORT_ZERO_COST_EXCEPTIONS
static bool client_dyld_find_unwind_sections(void* addr, dyld_unwind_sections* info);
#endif
#if DEPRECATED_APIS_SUPPORTED
#endif

static void unimplemented()
{
        dyld::halt("unimplemented dyld function\n");
}

struct dyld_func {
    const char* name;
    void*               implementation;
};

static struct dyld_func dyld_funcs[] = {
    {"__dyld_register_func_for_add_image",                              (void*)_dyld_register_func_for_add_image },
    {"__dyld_register_func_for_remove_image",                   (void*)_dyld_register_func_for_remove_image },
    {"__dyld_dladdr",                                                                   (void*)dladdr },
    {"__dyld_dlclose",                                                                  (void*)dlclose },
    {"__dyld_dlerror",                                                                  (void*)dlerror },
    {"__dyld_dlopen",                                                                   (void*)dlopen },
    {"__dyld_dlsym",                                                                    (void*)dlsym },
    {"__dyld_dlopen_preflight",                                                 (void*)dlopen_preflight },
        {"__dyld_image_count",                                                          (void*)_dyld_image_count },
    {"__dyld_get_image_header",                                                 (void*)_dyld_get_image_header },
    {"__dyld_get_image_vmaddr_slide",                                   (void*)_dyld_get_image_vmaddr_slide },
    {"__dyld_get_image_name",                                                   (void*)_dyld_get_image_name },
    {"__dyld_get_image_slide",                                                  (void*)_dyld_get_image_slide },
    {"__dyld__NSGetExecutablePath",                                             (void*)_NSGetExecutablePath },

        // SPIs
        {"__dyld_register_thread_helpers",                                      (void*)registerThreadHelpers },
        {"__dyld_fork_child",                                                           (void*)_dyld_fork_child },
    {"__dyld_make_delayed_module_initializer_calls",    (void*)_dyld_make_delayed_module_initializer_calls },
        {"__dyld_get_all_image_infos",                                          (void*)_dyld_get_all_image_infos },
#if SUPPORT_ZERO_COST_EXCEPTIONS
        {"__dyld_find_unwind_sections",                                         (void*)client_dyld_find_unwind_sections },
#endif
#if __i386__ || __x86_64__ || __arm__ || __arm64__
        {"__dyld_fast_stub_entry",                                                      (void*)dyld::fastBindLazySymbol },
#endif
        {"__dyld_image_path_containing_address",                        (void*)dyld_image_path_containing_address },
        {"__dyld_shared_cache_some_image_overridden",           (void*)dyld_shared_cache_some_image_overridden },
        {"__dyld_process_is_restricted",                                        (void*)dyld::processIsRestricted },
        {"__dyld_dynamic_interpose",                                            (void*)dyld_dynamic_interpose },
#if DYLD_SHARED_CACHE_SUPPORT
        {"__dyld_shared_cache_file_path",                                       (void*)dyld::getStandardSharedCacheFilePath },
#endif
    {"__dyld_get_image_header_containing_address",              (void*)dyld_image_header_containing_address },
    {"__dyld_is_memory_immutable",                                              (void*)_dyld_is_memory_immutable },
    {"__dyld_objc_notify_register",                                             (void*)_dyld_objc_notify_register },
    {"__dyld_get_shared_cache_uuid",                                    (void*)_dyld_get_shared_cache_uuid },


        // deprecated
#if DEPRECATED_APIS_SUPPORTED
    {"__dyld_lookup_and_bind",                                          (void*)client_dyld_lookup_and_bind },
    {"__dyld_lookup_and_bind_with_hint",                        (void*)_dyld_lookup_and_bind_with_hint },
    {"__dyld_lookup_and_bind_fully",                            (void*)_dyld_lookup_and_bind_fully },
    {"__dyld_install_handlers",                                         (void*)_dyld_install_handlers },
    {"__dyld_link_edit_error",                                          (void*)NSLinkEditError },
    {"__dyld_unlink_module",                                            (void*)NSUnLinkModule },
    {"__dyld_bind_objc_module",                                         (void*)_dyld_bind_objc_module },
    {"__dyld_bind_fully_image_containing_address",  (void*)_dyld_bind_fully_image_containing_address },
    {"__dyld_image_containing_address",                         (void*)_dyld_image_containing_address },
    {"__dyld_register_binding_handler",                         (void*)_dyld_register_binding_handler },
    {"__dyld_NSNameOfSymbol",                                           (void*)NSNameOfSymbol },
    {"__dyld_NSAddressOfSymbol",                                        (void*)NSAddressOfSymbol },
    {"__dyld_NSModuleForSymbol",                                        (void*)NSModuleForSymbol },
    {"__dyld_NSLookupAndBindSymbol",                            (void*)NSLookupAndBindSymbol },
    {"__dyld_NSLookupAndBindSymbolWithHint",            (void*)NSLookupAndBindSymbolWithHint },
    {"__dyld_NSLookupSymbolInModule",                           (void*)NSLookupSymbolInModule},
    {"__dyld_NSLookupSymbolInImage",                            (void*)NSLookupSymbolInImage},
    {"__dyld_NSMakePrivateModulePublic",                        (void*)NSMakePrivateModulePublic},
    {"__dyld_NSIsSymbolNameDefined",                            (void*)client_NSIsSymbolNameDefined},
    {"__dyld_NSIsSymbolNameDefinedWithHint",            (void*)NSIsSymbolNameDefinedWithHint },
    {"__dyld_NSIsSymbolNameDefinedInImage",                     (void*)NSIsSymbolNameDefinedInImage},
    {"__dyld_NSNameOfModule",                                           (void*)NSNameOfModule },
    {"__dyld_NSLibraryNameForModule",                           (void*)NSLibraryNameForModule },
    {"__dyld_NSAddLibrary",                                                     (void*)NSAddLibrary },
    {"__dyld_NSAddLibraryWithSearching",                        (void*)NSAddLibraryWithSearching },
    {"__dyld_NSAddImage",                                                       (void*)NSAddImage },
    {"__dyld_launched_prebound",                                        (void*)_dyld_launched_prebound },
    {"__dyld_all_twolevel_modules_prebound",            (void*)_dyld_all_twolevel_modules_prebound },
    {"__dyld_call_module_initializers_for_dylib",   (void*)_dyld_call_module_initializers_for_dylib },
    {"__dyld_NSCreateObjectFileImageFromFile",                  (void*)NSCreateObjectFileImageFromFile },
    {"__dyld_NSCreateObjectFileImageFromMemory",                (void*)NSCreateObjectFileImageFromMemory },
    {"__dyld_NSDestroyObjectFileImage",                                 (void*)NSDestroyObjectFileImage },
    {"__dyld_NSLinkModule",                                                             (void*)NSLinkModule },
    {"__dyld_NSHasModInitObjectFileImage",                              (void*)NSHasModInitObjectFileImage },
    {"__dyld_NSSymbolDefinitionCountInObjectFileImage", (void*)NSSymbolDefinitionCountInObjectFileImage },
    {"__dyld_NSSymbolDefinitionNameInObjectFileImage",  (void*)NSSymbolDefinitionNameInObjectFileImage },
    {"__dyld_NSIsSymbolDefinedInObjectFileImage",               (void*)NSIsSymbolDefinedInObjectFileImage },
    {"__dyld_NSSymbolReferenceNameInObjectFileImage",   (void*)NSSymbolReferenceNameInObjectFileImage },
    {"__dyld_NSSymbolReferenceCountInObjectFileImage",  (void*)NSSymbolReferenceCountInObjectFileImage },
    {"__dyld_NSGetSectionDataInObjectFileImage",                (void*)NSGetSectionDataInObjectFileImage },
#if OLD_LIBSYSTEM_SUPPORT
    {"__dyld_link_module",                                                      (void*)_dyld_link_module },
#endif
#endif //DEPRECATED_APIS_SUPPORTED

    {NULL, 0}
};



#if DEPRECATED_APIS_SUPPORTED

static void dyldAPIhalt(const char* apiName, const char* errorMsg)
{
        dyld::log("dyld: %s() error\n", apiName);
        dyld::halt(errorMsg);
}

// dyld's abstract type NSSymbol is implemented as const ImageLoader::Symbol*
inline NSSymbol SymbolToNSSymbol(const ImageLoader::Symbol* sym)
{
        return (NSSymbol)sym;
}       
inline const ImageLoader::Symbol* NSSymbolToSymbol(NSSymbol sym)
{
        return (const ImageLoader::Symbol*)sym;
}       

// dyld's abstract type NSModule is implemented as ImageLoader*
inline NSModule ImageLoaderToNSModule(const ImageLoader* image)
{
        return (NSModule)image;
}       
inline ImageLoader* NSModuleToImageLoader(NSModule module)
{
        ImageLoader* image = (ImageLoader*)module;
        if ( dyld::validImage(image) )
                return image;
        return NULL;
}

// actual definition for opaque type
struct __NSObjectFileImage
{
        ImageLoader*    image;  
        const void*             imageBaseAddress;       // not used with OFI created from files
        size_t                  imageLength;            // not used with OFI created from files
};


VECTOR_NEVER_DESTRUCTED(NSObjectFileImage);
static std::vector<NSObjectFileImage> sObjectFileImages;



//
// __NSObjectFileImage are deleted in NSDestroyObjectFileImage()
// The contained image is delete in one of two places:
//      NSUnLinkModule deletes the image if there is no __NSObjectFileImage with a reference to it
//      NSDestroyObjectFileImage deletes the image if image is not in list of valid images
//



static void setLastError(NSLinkEditErrors code, int errnum, const char* file, const char* message)
{
        dyld::setErrorMessage(message);
        strncpy(sLastErrorFilePath, file, 1024);
        sLastErrorFilePath[1023] = '\0';
        sLastErrorFileCode = code;
        sLastErrorNo = errnum;
}

#endif // DEPRECATED_APIS_SUPPORTED

/*
 *_dyld_NSGetExecutablePath is the dyld side of _NSGetExecutablePath which
 * copies the path of the executable into the buffer and returns 0 if the path
 * was successfully copied in the provided buffer. If the buffer is not large
 * enough, -1 is returned and the expected buffer size is copied in *bufsize.
 * Note that _NSGetExecutablePath will return "a path" to the executable not a
 * "real path" to the executable. That is the path may be a symbolic link and
 * not the real file. And with deep directories the total bufsize needed could
 * be more than MAXPATHLEN.
 */
int _NSGetExecutablePath(char* buf, uint32_t *bufsize)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(...)\n", __func__);
        const char* exePath = dyld::getExecutablePath();
        if(*bufsize < strlen(exePath) + 1){
            *bufsize = (uint32_t)(strlen(exePath) + 1);
            return -1;
        }
        strcpy(buf, exePath);
        return 0;
}

uint32_t _dyld_image_count(void)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
        return allImagesCount();
}

const struct mach_header* _dyld_get_image_header(uint32_t image_index)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%u)\n", __func__, image_index);
        return allImagesIndexedMachHeader(image_index);
}

intptr_t _dyld_get_image_vmaddr_slide(uint32_t image_index)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%u)\n", __func__, image_index);
        const struct mach_header* mh = allImagesIndexedMachHeader(image_index);
        if ( mh != NULL )
                return ImageLoaderMachO::computeSlide(mh);
        else
                return 0;
}

intptr_t _dyld_get_image_slide(const struct mach_header* mh)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, mh);
        return ImageLoaderMachO::computeSlide(mh);
}


const char* _dyld_get_image_name(uint32_t image_index)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%u)\n", __func__, image_index);
        return allImagesIndexedPath(image_index);
}

const struct mach_header * dyld_image_header_containing_address(const void* address)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, address);
#if SUPPORT_ACCELERATE_TABLES
        const mach_header* mh;
        const char* path;
        if ( dyld::addressInCache(address, &mh, &path) )
                return mh;
#endif
        ImageLoader* image = dyld::findImageContainingAddress(address);
        if ( image != NULL ) 
                return image->machHeader();
        return NULL;
}


void _dyld_register_func_for_add_image(void (*func)(const struct mach_header *mh, intptr_t vmaddr_slide))
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, (void *)func);
        dyld::registerAddCallback(func);
}

void _dyld_register_func_for_remove_image(void (*func)(const struct mach_header *mh, intptr_t vmaddr_slide))
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, (void *)func);
        dyld::registerRemoveCallback(func);
}



// called by crt before main() by programs linked with 10.4 or earlier crt1.o
static void _dyld_make_delayed_module_initializer_calls()
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
                
#if SUPPORT_OLD_CRT_INITIALIZATION
        if ( dyld::gRunInitializersOldWay )
                dyld::initializeMainExecutable();
#endif
}



#if DEPRECATED_APIS_SUPPORTED

//
// _dyld_call_module_initializers_for_dylib() is the dyld side of
// __initialize_Cplusplus() which is in dylib1.o.
// It is intended to only be called inside -init rouintes.
// -init routines are called before module initializers (what C++
// initializers use).  Calling __initialize_Cplusplus() in a -init
// routine causes the module initializers for an image to be called
// which then allows C++ to be used inside a -init routine
//
static void _dyld_call_module_initializers_for_dylib(const struct mach_header* mh_dylib_header)
{
        if ( dyld::gLogAPIs )
                dyld::log("__initialize_Cplusplus()\n");
        
        // for now, do nothing...
}


void _dyld_lookup_and_bind_fully(const char* symbolName, void** address, NSModule* module)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", %p, %p)\n", __func__, symbolName, address, module);
        ImageLoader* image;
        const ImageLoader::Symbol* sym;
        dyld::clearErrorMessage();
        if ( dyld::flatFindExportedSymbol(symbolName, &sym, (const ImageLoader**)&image) ) {    
                try {
                        image->bindAllLazyPointers(dyld::gLinkContext, true);
                        if ( address != NULL)
                                *address = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext);
                        if ( module != NULL)
                                *module = ImageLoaderToNSModule(image);
                }
                catch (const char* msg) {
                        dyldAPIhalt(__func__, msg);
                }
        }
        else {
                // on failure to find symbol return NULLs
                if ( address != NULL)
                        *address = NULL;
                if ( module != NULL)
                        *module = NULL;
        }
}

// Note: This cannot have public name because dyld is built with a static copy of libc.a
// which calls dyld_lookup_and_bind() and expects to find dyld's symbols not host process
static void client_dyld_lookup_and_bind(const char* symbolName, void** address, NSModule* module)
{
        if ( dyld::gLogAPIs )
                dyld::log("_dyld_lookup_and_bind(\"%s\", %p, %p)\n", symbolName, address, module);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        if ( dyld::flatFindExportedSymbol(symbolName, &sym, &image) ) {
                if ( address != NULL)
                        *address = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext);
                if ( module != NULL)
                        *module = ImageLoaderToNSModule(image);
        }
        else {
                // on failure to find symbol return NULLs
                if ( address != NULL)
                        *address = NULL;
                if ( module != NULL)
                        *module = NULL;
        }
}

void _dyld_lookup_and_bind_with_hint(const char* symbolName, const char* library_name_hint, void** address, NSModule* module)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", \"%s\", %p, %p)\n", __func__, symbolName, library_name_hint, address, module);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        // Look for library whose path contains the hint.  If that fails search everywhere
        if (  dyld::flatFindExportedSymbolWithHint(symbolName, library_name_hint, &sym, &image) 
          ||  dyld::flatFindExportedSymbol(symbolName, &sym, &image) ) {
                if ( address != NULL)
                        *address = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext);
                if ( module != NULL)
                        *module = ImageLoaderToNSModule(image);
        }
        else {
                // on failure to find symbol return NULLs
                if ( address != NULL)
                        *address = NULL;
                if ( module != NULL)
                        *module = NULL;
        }
}


NSSymbol NSLookupAndBindSymbol(const char *symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\")\n", __func__, symbolName);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        if ( dyld::flatFindExportedSymbol(symbolName, &sym, &image) ) {
                return SymbolToNSSymbol(sym);
        }
        // return NULL on failure
        return NULL;
}

NSSymbol NSLookupAndBindSymbolWithHint(const char* symbolName, const char* libraryNameHint)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", \"%s\")\n", __func__, symbolName, libraryNameHint);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        bool found = dyld::flatFindExportedSymbolWithHint(symbolName, libraryNameHint, &sym, &image);
        if ( ! found ) {
                // hint failed, do slow search of all images
                 found = dyld::flatFindExportedSymbol(symbolName, &sym, &image);
        }
        if ( found )
                return SymbolToNSSymbol(sym);
                
        // return NULL on failure and log
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", \"%s\") => NULL \n", __func__, symbolName, libraryNameHint);
        return NULL;
}




static __attribute__((noinline)) 
const struct mach_header* addImage(void* callerAddress, const char* path, bool search, bool dontLoad, bool matchInstallName, bool abortOnError)
{
        ImageLoader*    image = NULL;
        std::vector<const char*> rpathsFromCallerImage;
        try {
                dyld::clearErrorMessage();
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
                // like dlopen, use rpath from caller image and from main executable
                if ( callerImage != NULL )
                        callerImage->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                ImageLoader::RPathChain callersRPaths(NULL, &rpathsFromCallerImage);
                if ( callerImage != dyld::mainExecutable() ) {
                        dyld::mainExecutable()->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                }
                dyld::LoadContext context;
                context.useSearchPaths          = search;
                context.useFallbackPaths        = search;
                context.useLdLibraryPath        = false;
                context.implicitRPath           = false;
                context.matchByInstallName      = matchInstallName;
                context.dontLoad                        = dontLoad;
                context.mustBeBundle            = false;
                context.mustBeDylib                     = true;
                context.canBePIE                        = false;
                context.origin                          = callerImage != NULL ? callerImage->getPath() : NULL; // caller's image's path
                context.rpath                           = &callersRPaths;       // rpaths from caller and main executable

                unsigned cacheIndex;
                image = load(path, context, cacheIndex);
                if ( image != NULL ) {
                        if ( context.matchByInstallName )
                                image->setMatchInstallPath(true);
                        dyld::link(image, false, false, callersRPaths, cacheIndex);
                        dyld::runInitializers(image);
                        // images added with NSAddImage() can never be unloaded
                        image->setNeverUnload(); 
                }
        }
        catch (const char* msg) {
                dyld::garbageCollectImages();
                if ( abortOnError) {
                        char pathMsg[strlen(msg)+strlen(path)+4];
                        strcpy(pathMsg, msg);
                        strcat(pathMsg, " ");
                        strcat(pathMsg, path);
                        dyldAPIhalt("NSAddImage", pathMsg);
                }
                // not halting, so set error state for NSLinkEditError to find
                setLastError(NSLinkEditOtherError, 0, path, msg);
                free((void*)msg);       // our free() will do nothing if msg is a string literal
                image = NULL;
        }
        // free rpaths (getRPaths() malloc'ed each string)
        for(std::vector<const char*>::iterator it=rpathsFromCallerImage.begin(); it != rpathsFromCallerImage.end(); ++it) {
                const char* str = *it;
                free((void*)str);
        }
        if ( image == NULL )
                return NULL;
        else
                return image->machHeader();
}


const struct mach_header* NSAddImage(const char* path, uint32_t options)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", 0x%08X)\n", __func__, path, options);
        const bool dontLoad = ( (options & NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED) != 0 );
        const bool search = ( (options & NSADDIMAGE_OPTION_WITH_SEARCHING) != 0 );
        const bool matchInstallName = ( (options & NSADDIMAGE_OPTION_MATCH_FILENAME_BY_INSTALLNAME) != 0 );
        const bool abortOnError = ( (options & (NSADDIMAGE_OPTION_RETURN_ON_ERROR|NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED)) == 0 );
        void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
        return addImage(callerAddress, path, search, dontLoad, matchInstallName, abortOnError);
}

bool NSAddLibrary(const char* path)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\")\n", __func__, path);
        void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
        return (addImage(callerAddress, path, false, false, false, false) != NULL);
}

bool NSAddLibraryWithSearching(const char* path)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\")\n", __func__, path);
        void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
        return (addImage(callerAddress, path, true, false, false, false) != NULL);
}



//#define NSADDIMAGE_OPTION_NONE                        0x0
//#define NSADDIMAGE_OPTION_RETURN_ON_ERROR             0x1
//#define NSADDIMAGE_OPTION_MATCH_FILENAME_BY_INSTALLNAME       0x8

bool NSIsSymbolNameDefinedInImage(const struct mach_header* mh, const char* symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, \"%s\")\n", __func__, (void *)mh, symbolName);
        ImageLoader* image = dyld::findImageByMachHeader(mh);
        if ( image != NULL ) {
                if ( image->findExportedSymbol(symbolName, true, NULL) != NULL)
                        return true;
        }
        return false;
}


NSSymbol NSLookupSymbolInImage(const struct mach_header* mh, const char* symbolName, uint32_t options)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, \"%s\", 0x%08X)\n", __func__, mh, symbolName, options);
        const ImageLoader::Symbol* symbol = NULL;
        dyld::clearErrorMessage();
        ImageLoader* image = dyld::findImageByMachHeader(mh);
        if ( image != NULL ) {
                try {
                        if ( options & NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_FULLY ) {
                                image->bindAllLazyPointers(dyld::gLinkContext, true);
                        }
                        else if ( options & NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_NOW ) {
                                image->bindAllLazyPointers(dyld::gLinkContext, false);
                        }
                }
                catch (const char* msg) {
                        if ( (options & NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR) == 0 ) {
                                dyldAPIhalt(__func__, msg);
                        }
                }
                symbol = image->findExportedSymbol(symbolName, true, NULL);
        }
        if ( dyld::gLogAPIs && (symbol == NULL) )
                dyld::log("%s(%p, \"%s\", 0x%08X) ==> NULL\n", __func__, mh, symbolName, options);
        return SymbolToNSSymbol(symbol);
}


// Note: This cannot have public name because dyld is built with a static copy of libc.a
// which calls NSIsSymbolNameDefined() and expects to find dyld's symbols not host process
static bool client_NSIsSymbolNameDefined(const char* symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("NSIsSymbolNameDefined(\"%s\")\n", symbolName);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        return dyld::flatFindExportedSymbol(symbolName, &sym, &image);
}

bool NSIsSymbolNameDefinedWithHint(const char* symbolName, const char* libraryNameHint)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", \"%s\")\n", __func__, symbolName, libraryNameHint);
        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        bool found = dyld::flatFindExportedSymbolWithHint(symbolName, libraryNameHint, &sym, &image);
        if ( ! found ) {
                // hint failed, do slow search of all images
                 found = dyld::flatFindExportedSymbol(symbolName, &sym, &image);
        }
        if ( !found && dyld::gLogAPIs )
                dyld::log("%s(\"%s\", \"%s\") => false \n", __func__, symbolName, libraryNameHint);
        return found;
}

const char* NSNameOfSymbol(NSSymbol symbol)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, (void *)symbol);
        const char* result = NULL;
        ImageLoader* image = dyld::findImageContainingSymbol(symbol);
        if ( image != NULL ) 
                result = image->getExportedSymbolName(NSSymbolToSymbol(symbol));
        return result;
}

void* NSAddressOfSymbol(NSSymbol symbol)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, (void *)symbol);
        if ( symbol == NULL )
                return NULL;
        void* result = NULL;
        ImageLoader* image = dyld::findImageContainingSymbol(symbol);
        if ( image != NULL ) 
                result = (void*)image->getExportedSymbolAddress(NSSymbolToSymbol(symbol), dyld::gLinkContext);
        return result;
}

NSModule NSModuleForSymbol(NSSymbol symbol)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, (void *)symbol);
        NSModule result = NULL;
        ImageLoader* image = dyld::findImageContainingSymbol(symbol);
        if ( image != NULL ) 
                result = ImageLoaderToNSModule(image);
        return result;
}




bool _dyld_all_twolevel_modules_prebound(void)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
        return FALSE; 
}

void _dyld_bind_objc_module(const void *objc_module)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, objc_module);
        // do nothing, with new dyld everything already bound
}


bool _dyld_bind_fully_image_containing_address(const void* address)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, address);
        dyld::clearErrorMessage();
        ImageLoader* image = dyld::findImageContainingAddress(address);
        if ( image != NULL ) {
                try {
                        image->bindAllLazyPointers(dyld::gLinkContext, true);
                        return true;
                }
                catch (const char* msg) {
                        dyldAPIhalt(__func__, msg);
                }
        }
        return false;
}

bool _dyld_image_containing_address(const void* address)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, address);
        ImageLoader *imageLoader = dyld::findImageContainingAddress(address);
        return (NULL != imageLoader);
}

static NSObjectFileImage createObjectImageFile(ImageLoader* image, const void* address = NULL, size_t len=0)
{
        NSObjectFileImage result = new __NSObjectFileImage();
        result->image = image;
        result->imageBaseAddress = address;
        result->imageLength = len;
        sObjectFileImages.push_back(result);
        return result;
}

NSObjectFileImageReturnCode NSCreateObjectFileImageFromFile(const char* pathName, NSObjectFileImage *objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(\"%s\", ...)\n", __func__, pathName);
        try {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);

                dyld::LoadContext context;
                context.useSearchPaths          = false;
                context.useFallbackPaths        = false;
                context.useLdLibraryPath        = false;
                context.implicitRPath           = false;
                context.matchByInstallName      = false;
                context.dontLoad                        = false;
                context.mustBeBundle            = true;
                context.mustBeDylib                     = false;
                context.canBePIE                        = false;
                context.origin                          = callerImage != NULL ? callerImage->getPath() : NULL; // caller's image's path
                context.rpath                           = NULL; // support not yet implemented

                unsigned cacheIndex;
                ImageLoader* image = dyld::load(pathName, context, cacheIndex);
                // Note:  We DO NOT link the image!  NSLinkModule will do that
                if ( image != NULL ) {
                        if ( !image->isBundle() ) {
                                // the image must have been already loaded (since context.mustBeBundle will prevent it from being loaded)
                                return NSObjectFileImageInappropriateFile;
                        }
                        *objectFileImage = createObjectImageFile(image);
                        return NSObjectFileImageSuccess;
                }
        }
        catch (const char* msg) {
                //dyld::log("dyld: NSCreateObjectFileImageFromFile() error: %s\n", msg);
                dyld::garbageCollectImages();
                free((void*)msg);
                return NSObjectFileImageInappropriateFile;
        }
        return NSObjectFileImageFailure;
}


NSObjectFileImageReturnCode NSCreateObjectFileImageFromMemory(const void* address, size_t size, NSObjectFileImage *objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, %lu, %p)\n", __func__, address, size, objectFileImage);
        
        try {
                ImageLoader* image = dyld::loadFromMemory((const uint8_t*)address, size, NULL); 
                if ( ! image->isBundle() ) {
                        // this API can only be used with bundles...
                        dyld::garbageCollectImages();
                        return NSObjectFileImageInappropriateFile;
                }
                // Note:  We DO NOT link the image!  NSLinkModule will do that
                if ( image != NULL ) {
                        *objectFileImage = createObjectImageFile(image, address, size);
                        return NSObjectFileImageSuccess;
                }
        }
        catch (const char* msg) {
                free((void*)msg);
                dyld::garbageCollectImages();
                //dyld::log("dyld: NSCreateObjectFileImageFromMemory() error: %s\n", msg);
        }
        return NSObjectFileImageFailure;
}

static bool validOFI(NSObjectFileImage objectFileImage)
{
        const int ofiCount = sObjectFileImages.size();
        for (int i=0; i < ofiCount; ++i) {
                if ( sObjectFileImages[i] == objectFileImage )
                        return true;
        }
        return false;
}

bool NSDestroyObjectFileImage(NSObjectFileImage objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, objectFileImage);
        
        if ( validOFI(objectFileImage) ) {
                // a failure during NSLinkModule will delete the image
                if ( objectFileImage->image != NULL ) {
                        // if the image has never been linked or has been unlinked, the image is not in the list of valid images
                        // and we should delete it
                        bool linkedImage = dyld::validImage(objectFileImage->image);
                        if ( ! linkedImage )  {
                                ImageLoader::deleteImage(objectFileImage->image);
                                objectFileImage->image = NULL;
                        }
                }
                
                // remove from list of ofi's
                for (std::vector<NSObjectFileImage>::iterator it=sObjectFileImages.begin(); it != sObjectFileImages.end(); it++) {
                        if ( *it == objectFileImage ) {
                                sObjectFileImages.erase(it);
                                break;
                        }
                }
                
                // if object was created from a memory, release that memory
                // NOTE: this is the way dyld has always done this. NSCreateObjectFileImageFromMemory() hands over ownership of the memory to dyld
                if ( objectFileImage->imageBaseAddress != NULL ) {
                        bool freed = false;
                        if ( (dyld::gLibSystemHelpers != NULL) && (dyld::gLibSystemHelpers->version >= 6) ) {
                                size_t sz = (*dyld::gLibSystemHelpers->malloc_size)(objectFileImage->imageBaseAddress);
                                if ( sz != 0 ) {
                                        (*dyld::gLibSystemHelpers->free)((void*)(objectFileImage->imageBaseAddress));
                                        freed = true;
                                }
                        }
                        if ( ! freed )
                                vm_deallocate(mach_task_self(), (vm_address_t)objectFileImage->imageBaseAddress, objectFileImage->imageLength);
                }
                
                // free ofi object
                delete objectFileImage;
                
                return true;
        }
        return false;
}

bool NSHasModInitObjectFileImage(NSObjectFileImage objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, objectFileImage);
        return objectFileImage->image->needsInitialization();
}

uint32_t NSSymbolDefinitionCountInObjectFileImage(NSObjectFileImage objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, objectFileImage);
        return objectFileImage->image->getExportedSymbolCount();
}

const char* NSSymbolDefinitionNameInObjectFileImage(NSObjectFileImage objectFileImage, uint32_t ordinal)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p,%d)\n", __func__, objectFileImage, ordinal);
        const ImageLoader::Symbol* sym = objectFileImage->image->getIndexedExportedSymbol(ordinal);
        return objectFileImage->image->getExportedSymbolName(sym);      
}

uint32_t NSSymbolReferenceCountInObjectFileImage(NSObjectFileImage objectFileImage)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, objectFileImage);
        return objectFileImage->image->getImportedSymbolCount();
}

const char * NSSymbolReferenceNameInObjectFileImage(NSObjectFileImage objectFileImage, uint32_t ordinal, 
                                                                                                        bool* tentative_definition)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p,%d)\n", __func__, objectFileImage, ordinal);
        const ImageLoader::Symbol* sym = objectFileImage->image->getIndexedImportedSymbol(ordinal);
        if ( tentative_definition != NULL ) {
                ImageLoader::ReferenceFlags flags = objectFileImage->image->getImportedSymbolInfo(sym);
                if ( (flags & ImageLoader::kTentativeDefinition) != 0 )
                        *tentative_definition = true;
                else
                        *tentative_definition = false;
        }
        return objectFileImage->image->getImportedSymbolName(sym);      
}

void* NSGetSectionDataInObjectFileImage(NSObjectFileImage objectFileImage,
                                                                                const char* segmentName, const char* sectionName, unsigned long* size)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p,%s, %s)\n", __func__, objectFileImage, segmentName, sectionName);

        void* start;
        size_t length;
        if ( objectFileImage->image->getSectionContent(segmentName, sectionName, &start, &length) ) {
                if ( size != NULL )
                        *size = length;
                return start;
        }
        return NULL;
}



bool NSIsSymbolDefinedInObjectFileImage(NSObjectFileImage objectFileImage, const char* symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p,%s)\n", __func__, objectFileImage, symbolName);
        const ImageLoader::Symbol* sym = objectFileImage->image->findExportedSymbol(symbolName, true, NULL);
        return ( sym != NULL );
}



NSModule NSLinkModule(NSObjectFileImage objectFileImage, const char* moduleName, uint32_t options)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, \"%s\", 0x%08X)\n", __func__, objectFileImage, moduleName, options); 
        
        dyld::clearErrorMessage();
        try {
                if ( (options & NSLINKMODULE_OPTION_CAN_UNLOAD) != 0 )
                        objectFileImage->image->setCanUnload();

                // NSLinkModule allows a bundle to be link multpile times
                // each link causes the bundle to be copied to a new address
                if ( objectFileImage->image->isLinked() ) {
                        // already linked, so clone a new one and link it
                        objectFileImage->image = dyld::cloneImage(objectFileImage->image);
                }
                
                // for memory based images, set moduleName as the name anyone calling _dyld_get_image_name() will see
                if ( objectFileImage->image->getPath() == NULL ) {
                        objectFileImage->image->setPath(moduleName);
                        // <rdar://problem/8812589> dyld has NULL paths in image info array
                        dyld_image_info info;
                        info.imageLoadAddress = objectFileImage->image->machHeader();
                        info.imageFilePath = moduleName;
                        info.imageFileModDate = 0;
                        addImagesToAllImages(1, &info);
                }

                // support private bundles
                if ( (options & NSLINKMODULE_OPTION_PRIVATE) != 0 )
                        objectFileImage->image->setHideExports();
        
                // set up linking options
                bool forceLazysBound = ( (options & NSLINKMODULE_OPTION_BINDNOW) != 0 );
                
                // load libraries, rebase, bind, to make this image usable
                dyld::link(objectFileImage->image, forceLazysBound, false, ImageLoader::RPathChain(NULL,NULL), UINT32_MAX);
                
                // bump reference count to keep this bundle from being garbage collected
                objectFileImage->image->incrementDlopenReferenceCount();

                // run initializers unless magic flag says not to
                if ( (options & NSLINKMODULE_OPTION_DONT_CALL_MOD_INIT_ROUTINES) == 0 )
                        dyld::runInitializers(objectFileImage->image);

                return ImageLoaderToNSModule(objectFileImage->image);
        }
        catch (const char* msg) {
                dyld::garbageCollectImages();
                if ( (options & NSLINKMODULE_OPTION_RETURN_ON_ERROR) == 0 )
                        dyldAPIhalt(__func__, msg);
                // not halting, so set error state for NSLinkEditError to find
                setLastError(NSLinkEditOtherError, 0, moduleName, msg);
                // dyld::link() deleted the image so lose our reference
                objectFileImage->image = NULL;
                free((void*)msg);
                return NULL;
        }
}


#if OLD_LIBSYSTEM_SUPPORT
// This is for compatibility with old libSystems (libdyld.a) which process ObjectFileImages outside dyld
static NSModule _dyld_link_module(NSObjectFileImage object_addr, size_t object_size, const char* moduleName, uint32_t options)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, \"%s\", 0x%08X)\n", "NSLinkModule", object_addr,  moduleName, options); // note name/args translation
        ImageLoader* image = NULL;
        dyld::clearErrorMessage();
        try {
                const char* imageName = moduleName;                     
                image = dyld::loadFromMemory((const uint8_t*)object_addr, object_size, imageName); 
                
                if ( image != NULL ) {          
                        // support private bundles
                        if ( (options & NSLINKMODULE_OPTION_PRIVATE) != 0 )
                                image->setHideExports();
                
                        // set up linking options
                        bool forceLazysBound = ( (options & NSLINKMODULE_OPTION_BINDNOW) != 0 );
                        
                        // load libraries, rebase, bind, to make this image usable
                        dyld::link(image, forceLazysBound, false, ImageLoader::RPathChain(NULL,NULL), UINT32_MAX);
                        
                        // run initializers unless magic flag says not to
                        if ( (options & NSLINKMODULE_OPTION_DONT_CALL_MOD_INIT_ROUTINES) == 0 )
                                dyld::runInitializers(image);
                }
        }
        catch (const char* msg) {
                if ( (options & NSLINKMODULE_OPTION_RETURN_ON_ERROR) == 0 )
                        dyldAPIhalt("NSLinkModule", msg);
                // not halting, so set error state for NSLinkEditError to find
                setLastError(NSLinkEditOtherError, 0, moduleName, msg);
                // if image was created for this bundle, destroy it
                if ( image != NULL ) {
                        dyld::removeImage(image);
                        ImageLoader::deleteImage(image);
                }
                image = NULL;
                free((void*)msg);
        }
        return ImageLoaderToNSModule(image);
}
#endif

NSSymbol NSLookupSymbolInModule(NSModule module, const char* symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, \"%s\")\n", __func__, (void *)module, symbolName);
        ImageLoader* image = NSModuleToImageLoader(module);
        if ( image == NULL ) 
                return NULL;
        return SymbolToNSSymbol(image->findExportedSymbol(symbolName, false, NULL));
}

const char* NSNameOfModule(NSModule module)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, module);
        ImageLoader* image = NSModuleToImageLoader(module);
        if ( image == NULL ) 
                return NULL;
        return image->getPath();
}

const char* NSLibraryNameForModule(NSModule module)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, module);
        ImageLoader* image = NSModuleToImageLoader(module);
        if ( image == NULL ) 
                return NULL;
        return image->getPath();
}

bool NSUnLinkModule(NSModule module, uint32_t options)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, 0x%08X)\n", __func__, module, options); 
        if ( module == NULL )
                return false;
        ImageLoader* image = NSModuleToImageLoader(module);
        if ( image == NULL ) 
                return false;
        dyld::runImageStaticTerminators(image);
        if ( (dyld::gLibSystemHelpers != NULL) && (dyld::gLibSystemHelpers->version >= 13) ) {
                __cxa_range_t ranges[image->segmentCount()];
                int rangeCount = 0;
                for (unsigned int j=0; j < image->segmentCount(); ++j) {
                        if ( !image->segExecutable(j) )
                                continue;
                        ranges[rangeCount].addr = (const void*)image->segActualLoadAddress(j);
                        ranges[rangeCount].length = image->segSize(j);
                        ++rangeCount;
                }
                (*dyld::gLibSystemHelpers->cxa_finalize_ranges)(ranges, rangeCount);
        }
        dyld::removeImage(image);
        
        if ( (options & NSUNLINKMODULE_OPTION_KEEP_MEMORY_MAPPED) != 0 )
                image->setLeaveMapped();
                
        // TODO: NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES

        // Only delete image if there is no ofi referencing it
        // That means the ofi was destroyed after linking, so no one is left to delete this image       
        const int ofiCount = sObjectFileImages.size();
        bool found = false;
        for (int i=0; i < ofiCount; ++i) {
                NSObjectFileImage ofi = sObjectFileImages[i];
                if ( ofi->image == image )
                        found = true;
        }
        if ( !found )
                ImageLoader::deleteImage(image);
        
        return true;
}

// internal name and parameters do not match public name and parameters...
static void _dyld_install_handlers(void* undefined, void* multiple, void* linkEdit)
{
        if ( dyld::gLogAPIs )
                dyld::log("NSLinkEditErrorHandlers()\n");

        dyld::registerUndefinedHandler((dyld::UndefinedHandler)undefined);
        // no support for multiple or linkedit handlers
}




void NSLinkEditError(NSLinkEditErrors* c, int* errorNumber, const char** fileName, const char** errorString)
{
        // FIXME FIXME
        *c = sLastErrorFileCode;
        *errorNumber = sLastErrorNo;
        *fileName = sLastErrorFilePath;
        *errorString = dyld::getErrorMessage();
}



static void _dyld_register_binding_handler(void * (*bindingHandler)(const char *, const char *, void *), ImageLoader::BindingOptions bindingOptions)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
        dyld::gLinkContext.bindingHandler = bindingHandler;
        dyld::gLinkContext.bindingOptions = bindingOptions;
}

#endif //DEPRECATED_APIS_SUPPORTED


// Call by fork() in libSystem after the kernel trap is done on the child side
void _dyld_fork_child()
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
        // The implementation of fork() in libSystem knows to reset the variable mach_task_self_
        // in libSystem for the child of a fork.  But dyld is built with a static copy
        // of libc.a and has its own copy of mach_task_self_ which we reset here.
        //
        // In mach_init.h mach_task_self() is #defined to mach_task_self_ and
        // in mach_init() mach_task_self_ is initialized to task_self_trap().
        //
        extern mach_port_t      mach_task_self_;
        mach_task_self_ = task_self_trap();
        
        // If dyld is sending load/unload notices to CoreSymbolication, the shared memory
        // page is not copied on fork. <rdar://problem/6797342>
        // NULL the CoreSymbolication shared memory pointer to prevent a crash.
        dyld::gProcessInfo->coreSymbolicationShmPage = NULL;
        // for safety, make sure child starts with clean systemOrderFlag
        dyld::gProcessInfo->systemOrderFlag = 0;
}


#if DEPRECATED_APIS_SUPPORTED
// returns true if prebinding was used in main executable
bool _dyld_launched_prebound()
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);
                
        // ¥¥¥Êif we deprecate prebinding, we may want to consider always returning true or false here
        return dyld::mainExecutablePrebound();
}


//
// _dyld_NSMakePrivateModulePublic() is the dyld side of the hack
// NSMakePrivateModulePublic() needed for the dlopen() to turn it's
// RTLD_LOCAL handles into RTLD_GLOBAL.  It just simply turns off the private
// flag on the image for this module.  If the module was found and it was
// private then everything worked and TRUE is returned else FALSE is returned.
//
static bool NSMakePrivateModulePublic(NSModule module)
{
        ImageLoader* image = NSModuleToImageLoader(module);
        if ( image != NULL ) {
                if ( image->hasHiddenExports() ) {
                        image->setHideExports(false);
                        return true;
                }
        }
        return false;
}

#endif // DEPRECATED_APIS_SUPPORTED

int _dyld_func_lookup(const char* name, void** address)
{
        for (const dyld_func* p = dyld_funcs; p->name != NULL; ++p) {
            if ( strcmp(p->name, name) == 0 ) {
                        if( p->implementation == unimplemented )
                                dyld::log("unimplemented dyld function: %s\n", p->name);
                        *address = p->implementation;
                        return true;
            }
        }
        *address = 0;
        return false;
}


static void registerThreadHelpers(const dyld::LibSystemHelpers* helpers)
{
        dyld::gLibSystemHelpers = helpers;
        
#if !SUPPORT_ZERO_COST_EXCEPTIONS
        if ( helpers->version >= 5 )  {
                // create key use by dyld exception handling
                pthread_key_t key;
                int result = helpers->pthread_key_create(&key, NULL);
                if ( result == 0 )
                        __Unwind_SjLj_SetThreadKey(key);
        }
#endif
}


static void dlerrorClear()
{
        if ( dyld::gLibSystemHelpers != NULL ) {
                // <rdar://problem/10595338> dlerror buffer leak
                // dlerrorClear() should not force allocation, but zero it if already allocated
                if ( dyld::gLibSystemHelpers->version >= 10 ) {
                        if ( ! (*dyld::gLibSystemHelpers->hasPerThreadBufferFor_dlerror)() )
                                return;
                }

                // first char of buffer is flag whether string (starting at second char) is valid
                char* buffer = (*dyld::gLibSystemHelpers->getThreadBufferFor_dlerror)(2);
                buffer[0] = '\0';
                buffer[1] = '\0';
        }
}

static void dlerrorSet(const char* msg)
{
        if ( dyld::gLibSystemHelpers != NULL ) {
                // first char of buffer is flag whether string (starting at second char) is valid
                char* buffer = (*dyld::gLibSystemHelpers->getThreadBufferFor_dlerror)(strlen(msg)+2);
                buffer[0] = '\1';
                strcpy(&buffer[1], msg);
        }
}


bool dlopen_preflight(const char* path)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%s)\n", __func__, path);

        dlerrorClear();
        
        CRSetCrashLogMessage("dyld: in dlopen_preflight()");

        const bool leafName = (strchr(path, '/') == NULL);
        const bool absolutePath = (path[0] == '/');
#if __IPHONE_OS_VERSION_MIN_REQUIRED
        char canonicalPath[PATH_MAX]; 
        // <rdar://problem/7017050> dlopen() not opening frameworks from shared cache with // or ./ in path
        if ( !leafName ) {
                // make path canonical if it contains a // or ./
                if ( (strstr(path, "//") != NULL) || (strstr(path, "./") != NULL) ) {
                        const char* lastSlash = strrchr(path, '/');
                        char dirPath[PATH_MAX]; 
                        if ( strlcpy(dirPath, path, sizeof(dirPath)) < sizeof(dirPath) ) {
                                dirPath[lastSlash-path] = '\0';
                                if ( realpath(dirPath, canonicalPath) ) {
                                        strlcat(canonicalPath, "/", sizeof(canonicalPath));
                                        if ( strlcat(canonicalPath, lastSlash+1, sizeof(canonicalPath)) < sizeof(canonicalPath) ) {
                                                // if all fit in buffer, use new canonical path
                                                path = canonicalPath;
                                        }
                                }
                        }
                }
        }
#endif
#if SUPPORT_ACCELERATE_TABLES
        if  ( dyld::isPathInCache(path) )
                return true;
#endif

#if DYLD_SHARED_CACHE_SUPPORT
        // <rdar://problem/5910137> dlopen_preflight() on image in shared cache leaves it loaded but not objc initialized
        // if requested path is to something in the dyld shared cache, always succeed
        if ( dyld::inSharedCache(path) )
                return true;
#endif
        
        bool result = false;
        std::vector<const char*> rpathsFromCallerImage;
        try {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
                // for dlopen, use rpath from caller image and from main executable
                if ( callerImage != NULL )
                        callerImage->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                ImageLoader::RPathChain callersRPaths(NULL, &rpathsFromCallerImage);
                if ( callerImage != dyld::mainExecutable() ) {
                        dyld::mainExecutable()->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                }

                ImageLoader*    image = NULL;
                dyld::LoadContext context;
                context.useSearchPaths  = true;
                context.useFallbackPaths= leafName;                                     // a partial path implies don't use fallback paths
                context.useLdLibraryPath= leafName;                                     // a leafname implies should search 
                context.implicitRPath   = !absolutePath;                        // a non-absolute path implies try rpath searching 
                context.matchByInstallName = true;
                context.dontLoad                = false;
                context.mustBeBundle    = false;
                context.mustBeDylib             = false;
                context.canBePIE                = true;
                context.origin                  = callerImage != NULL ? callerImage->getPath() : NULL; // caller's image's path
                context.rpath                   = &callersRPaths;       // rpaths from caller and main executable

                unsigned cacheIndex;
                image = load(path, context, cacheIndex);
                if ( image != NULL ) {
                        dyld::preflight(image, callersRPaths, cacheIndex);      // image object deleted by dyld::preflight()
                        result = true;
                }
        }
        catch (const char* msg) {
                const char* str = dyld::mkstringf("dlopen_preflight(%s): %s", path, msg);
                dlerrorSet(str);
                free((void*)str);
                free((void*)msg);       // our free() will do nothing if msg is a string literal
        }
        // free rpaths (getRPaths() malloc'ed each string)
        for(std::vector<const char*>::iterator it=rpathsFromCallerImage.begin(); it != rpathsFromCallerImage.end(); ++it) {
                const char* str = *it;
                free((void*)str);
        }
        CRSetCrashLogMessage(NULL);
        return result;
}

#if SUPPORT_ACCELERATE_TABLES
bool static callerIsNonOSApp(void* callerAddress, const char** shortName)
{
        *shortName = NULL;
        const mach_header* unusedMh;
        const char* unusedPath;
        unsigned unusedIndex;
        // any address in shared cache is not from app
        if ( dyld::addressInCache(callerAddress, &unusedMh, &unusedPath, &unusedIndex) )
                return false;

        ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
        if ( callerImage == NULL )
                return false;

        *shortName = callerImage->getShortName();
        return ( strncmp(callerImage->getPath(), "/var/containers/", 16) == 0 );
}
#endif

void* dlopen(const char* path, int mode)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%s, 0x%08X)\n", __func__, ((path==NULL) ? "NULL" : path), mode);

#if SUPPORT_ACCELERATE_TABLES
        if ( dyld::gLogAppAPIs ) {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                const char* shortName;
                if ( callerIsNonOSApp(callerAddress, &shortName) ) {
                        dyld::log("%s: %s(%s, 0x%08X)\n", shortName, __func__, ((path==NULL) ? "NULL" : path), mode);
                }
        }
#endif

        dlerrorClear();

        // passing NULL for path means return magic object
        if ( path == NULL ) {
                // RTLD_FIRST means any dlsym() calls on the handle should only search that handle and not subsequent images
                if ( (mode & RTLD_FIRST) != 0 )
                        return RTLD_MAIN_ONLY;
                else
                        return RTLD_DEFAULT;
        }
        
        // acquire global dyld lock (dlopen is special - libSystem glue does not do locking)
        bool lockHeld = false;
        if ( (dyld::gLibSystemHelpers != NULL) && (dyld::gLibSystemHelpers->version >= 4) ) {
                dyld::gLibSystemHelpers->acquireGlobalDyldLock();
                CRSetCrashLogMessage("dyld: in dlopen()");
                lockHeld = true;
        }
                
        void* result = NULL;
        const bool leafName = (strchr(path, '/') == NULL);
        const bool absolutePath = (path[0] == '/');
#if __IPHONE_OS_VERSION_MIN_REQUIRED
        char canonicalPath[PATH_MAX]; 
        // <rdar://problem/7017050> dlopen() not opening frameworks from shared cache with // or ./ in path
        if ( !leafName ) {
                // make path canonical if it contains a // or ./
                if ( (strstr(path, "//") != NULL) || (strstr(path, "./") != NULL) ) {
                        const char* lastSlash = strrchr(path, '/');
                        char dirPath[PATH_MAX]; 
                        if ( strlcpy(dirPath, path, sizeof(dirPath)) < sizeof(dirPath) ) {
                                dirPath[lastSlash-path] = '\0';
                                if ( realpath(dirPath, canonicalPath) ) {
                                        strlcat(canonicalPath, "/", sizeof(canonicalPath));
                                        if ( strlcat(canonicalPath, lastSlash+1, sizeof(canonicalPath)) < sizeof(canonicalPath) ) {
                                                // if all fit in buffer, use new canonical path
                                                path = canonicalPath;
                                        }
                                }
                        }
                }
        }
#endif
#if SUPPORT_ACCELERATE_TABLES
        if ( dyld::dlopenFromCache(path, mode, &result) ) {
                // Note: dlopenFromCache() releases the lock
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(%s) ==> %p\n", __func__, path, result);
                return result;
        }
#endif

        ImageLoader* image = NULL;
        std::vector<const char*> rpathsFromCallerImage;
        ImageLoader::RPathChain callersRPaths(NULL, &rpathsFromCallerImage);
        try {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
                if ( (mode & RTLD_NOLOAD) == 0 ) {
                        // for dlopen, use rpath from caller image and from main executable
                        if ( callerImage != NULL )
                                callerImage->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                        if ( callerImage != dyld::mainExecutable() )
                                dyld::mainExecutable()->getRPaths(dyld::gLinkContext, rpathsFromCallerImage);
                }
 
                dyld::LoadContext context;
                context.useSearchPaths  = true;
                context.useFallbackPaths= leafName;                             // a partial path means no fallback paths
                context.useLdLibraryPath= leafName;                             // a leafname implies should search 
                context.implicitRPath   = !absolutePath;                // a non-absolute path implies try rpath searching 
                context.matchByInstallName = true;
                context.dontLoad                = ( (mode & RTLD_NOLOAD) != 0 );
                context.mustBeBundle    = false;
                context.mustBeDylib             = false;
                context.canBePIE                = true;
                context.origin                  = callerImage != NULL ? callerImage->getPath() : NULL; // caller's image's path
                context.rpath                   = &callersRPaths;                               // rpaths from caller and main executable

                unsigned cacheIndex;
                image = load(path, context, cacheIndex);
#if SUPPORT_ACCELERATE_TABLES
                if ( (image != NULL) && (cacheIndex != UINT32_MAX) ) {
                        if ( dyld::makeCacheHandle(image, cacheIndex, mode, &result) ) {
                                if ( dyld::gLogAPIs )
                                        dyld::log("  %s(%s) ==> %p\n", __func__, path, result);
                                if ( lockHeld )
                                        dyld::gLibSystemHelpers->releaseGlobalDyldLock();
                                return result;
                        }
                }
#endif
                if ( image != NULL ) {
                        // bump reference count.  Do this before link() so that if an initializer calls dlopen and fails
                        // this image is not garbage collected
                        image->incrementDlopenReferenceCount();
                        // link in all dependents
                        if ( (mode & RTLD_NOLOAD) == 0 ) {
                                bool alreadyLinked = image->isLinked();
                                bool forceLazysBound = ( (mode & RTLD_NOW) != 0 );
                                dyld::link(image, forceLazysBound, false, callersRPaths, cacheIndex);
                                if ( ! alreadyLinked ) {
                                        // only hide exports if image is not already in use
                                        if ( (mode & RTLD_LOCAL) != 0 )
                                                image->setHideExports(true);
                                }
                        }
                        
                        // RTLD_NODELETE means don't unmap image even after dlclosed. This is what dlcompat did on Mac OS X 10.3
                        // On other *nix OS's, it means dlclose() should do nothing, but the handle should be invalidated. 
                        // The subtle differences are: 
                        //  1) if the image has any termination routines, whether they are run during dlclose or when the process terminates
                        //  2) If someone does a supsequent dlopen() on the same image, whether the same address should be used. 
                        if ( (mode & RTLD_NODELETE) != 0 )
                                image->setLeaveMapped();
                        
                        // release global dyld lock early, this enables initializers to do threaded operations
                        if ( lockHeld ) {
                                CRSetCrashLogMessage(NULL);
                                dyld::gLibSystemHelpers->releaseGlobalDyldLock();
                                lockHeld = false;
                        }
                        
                        // RTLD_NOLOAD means dlopen should fail unless path is already loaded. 
                        // don't run initializers when RTLD_NOLOAD is set.  This only matters if dlopen() is
                        // called from within an initializer because it can cause initializers to run
                        // out of order. Most uses of RTLD_NOLOAD are "probes".  If they want initialzers
                        // to run, then don't use RTLD_NOLOAD.
                        if ( (mode & RTLD_NOLOAD) == 0 ) {
                                // run initializers
                                dyld::runInitializers(image);
                        }
                        
                        // RTLD_FIRST means any dlsym() calls on the handle should only search that handle and not subsequent images
                        // this is tracked by setting the low bit of the handle, which is usually zero by malloc alignment
                        if ( (mode & RTLD_FIRST) != 0 )
                                result = (void*)(((uintptr_t)image)|1);
                        else
                                result = image;
                }
        }
        catch (const char* msg) {
                if ( image != NULL ) {
                        // load() succeeded but, link() failed
                        // back down reference count and do GC
                        image->decrementDlopenReferenceCount();
                        if ( image->dlopenCount() == 0 )
                                dyld::garbageCollectImages();
                }
                const char* str = dyld::mkstringf("dlopen(%s, %d): %s", path, mode, msg);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s() failed, error: '%s'\n", __func__, str);
                dlerrorSet(str);
                free((void*)str);
                free((void*)msg);       // our free() will do nothing if msg is a string literal
                result = NULL;
        }
        // free rpaths (getRPaths() malloc'ed each string)
        for(std::vector<const char*>::iterator it=rpathsFromCallerImage.begin(); it != rpathsFromCallerImage.end(); ++it) {
                const char* str = *it;
                free((void*)str);
        }
        
        // when context.dontLoad is set, load() returns NULL instead of throwing an exception 
        if ( (mode & RTLD_NOLOAD) && (result == NULL) ) {
                dlerrorSet("image not already loaded");
        }
        
        if ( lockHeld ) {
                CRSetCrashLogMessage(NULL);
                dyld::gLibSystemHelpers->releaseGlobalDyldLock();
        }
        if ( dyld::gLogAPIs && (result != NULL) )
                dyld::log("  %s(%s) ==> %p\n", __func__, path, result);
        return result;
}



int dlclose(void* handle)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, handle);

        // silently accept magic handles for main executable
        if ( handle == RTLD_MAIN_ONLY )
                return 0;
        if ( handle == RTLD_DEFAULT )
                return 0;
        
        ImageLoader* image = (ImageLoader*)(((uintptr_t)handle) & (-4));        // clear mode bits
        if ( dyld::validImage(image) ) {
                dlerrorClear();
                // decrement use count
                if ( image->decrementDlopenReferenceCount() ) {
                        dlerrorSet("dlclose() called too many times");
                        return -1;
                }
                // remove image if reference count went to zero
                if ( image->dlopenCount() == 0 )
                        dyld::garbageCollectImages();
                return 0;
        }
        else {
                dlerrorSet("invalid handle passed to dlclose()");
                return -1;
        }
}



int dladdr(const void* address, Dl_info* info)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, %p)\n", __func__, address, info);

        CRSetCrashLogMessage("dyld: in dladdr()");
#if SUPPORT_ACCELERATE_TABLES
        if ( dyld::dladdrFromCache(address, info) ) {
                CRSetCrashLogMessage(NULL);
                return 1; // success
        }
#endif

        ImageLoader* image = dyld::findImageContainingAddress(address);
        if ( image != NULL ) {
                info->dli_fname = image->getRealPath();
                info->dli_fbase = (void*)image->machHeader();
                if ( address == info->dli_fbase ) {
                        // special case lookup of header
                        info->dli_sname = "__dso_handle";
                        info->dli_saddr = info->dli_fbase;
                        CRSetCrashLogMessage(NULL);
                        return 1; // success
                }
                // find closest symbol in the image
                info->dli_sname = image->findClosestSymbol(address, (const void**)&info->dli_saddr);
                // never return the mach_header symbol
                if ( info->dli_saddr == info->dli_fbase ) {
                        info->dli_sname = NULL;
                        info->dli_saddr = NULL;
                        CRSetCrashLogMessage(NULL);
                        return 1; // success
                }
                if ( info->dli_sname != NULL ) {
                        if ( info->dli_sname[0] == '_' )
                                info->dli_sname = info->dli_sname +1; // strip off leading underscore
                        //dyld::log("dladdr(%p) => %p %s\n", address, info->dli_saddr, info->dli_sname);
                        CRSetCrashLogMessage(NULL);
                        return 1; // success
                }
                info->dli_sname = NULL;
                info->dli_saddr = NULL;
                CRSetCrashLogMessage(NULL);
                return 1; // success
        }
        CRSetCrashLogMessage(NULL);
        return 0;  // failure
}


char* dlerror()
{
        if ( dyld::gLogAPIs )
                dyld::log("%s()\n", __func__);

        if ( dyld::gLibSystemHelpers != NULL ) {
                // if using newer libdyld.dylib and buffer if buffer not yet allocated, return NULL
                if ( dyld::gLibSystemHelpers->version >= 10 ) {
                        if ( ! (*dyld::gLibSystemHelpers->hasPerThreadBufferFor_dlerror)() )
                                return NULL;
                }

                // first char of buffer is flag whether string (starting at second char) is valid
                char* buffer = (*dyld::gLibSystemHelpers->getThreadBufferFor_dlerror)(2);
                if ( buffer[0] != '\0' ) {      // if valid buffer
                        buffer[0] = '\0';               // mark invalid, so next call to dlerror returns NULL
                        return &buffer[1];              // return message
                }
        }
        return NULL;
}

void* dlsym(void* handle, const char* symbolName)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, %s)\n", __func__, handle, symbolName);

#if SUPPORT_ACCELERATE_TABLES
        if ( dyld::gLogAppAPIs ) {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                const char* shortName;
                if ( callerIsNonOSApp(callerAddress, &shortName) ) {
                        dyld::log("%s: %s(%p, %s)\n", shortName, __func__, handle, symbolName);
                }
        }
#endif

        CRSetCrashLogMessage("dyld: in dlsym()");
        dlerrorClear();

        const ImageLoader* image;
        const ImageLoader::Symbol* sym;
        void* result;

        // dlsym() assumes symbolName passed in is same as in C source code
        // dyld assumes all symbol names have an underscore prefix
        char underscoredName[strlen(symbolName)+2];
        underscoredName[0] = '_';
        strcpy(&underscoredName[1], symbolName);
        
        // magic "search all" handle
        if ( handle == RTLD_DEFAULT ) {
                if ( dyld::flatFindExportedSymbol(underscoredName, &sym, &image) ) {
                        CRSetCrashLogMessage(NULL);
                        result = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext, NULL, false, underscoredName);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_DEFAULT, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
                const char* str = dyld::mkstringf("dlsym(RTLD_DEFAULT, %s): symbol not found", symbolName);
                dlerrorSet(str);
                free((void*)str);
                CRSetCrashLogMessage(NULL);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(RTLD_DEFAULT, %s) ==> NULL\n", __func__, symbolName);
                return NULL;
        }
        
        // magic "search only main executable" handle
        else if ( handle == RTLD_MAIN_ONLY ) {
                image = dyld::mainExecutable();
                sym = image->findExportedSymbol(underscoredName, true, &image); // search RTLD_FIRST way
                if ( sym != NULL ) {
                        CRSetCrashLogMessage(NULL);
                        result = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext, NULL, false, underscoredName);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_MAIN_ONLY, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
                const char* str = dyld::mkstringf("dlsym(RTLD_MAIN_ONLY, %s): symbol not found", symbolName);
                dlerrorSet(str);
                free((void*)str);
                CRSetCrashLogMessage(NULL);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(RTLD_MAIN_ONLY, %s) ==> NULL\n", __func__, symbolName);
                return NULL;
        }
        
        // magic "search what I would see" handle
        else if ( handle == RTLD_NEXT ) {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
#if SUPPORT_ACCELERATE_TABLES
                const mach_header* mh;
                const char* path;
                unsigned index;
                if ( dyld::addressInCache(callerAddress, &mh, &path, &index) ) {
                        // if dylib in cache is calling dlsym(RTLD_NEXT,xxx) handle search differently
                        result = dyld::dlsymFromCache(RTLD_NEXT, underscoredName, index);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_NEXT, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
#endif
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
                sym = callerImage->findExportedSymbolInDependentImages(underscoredName, dyld::gLinkContext, &image); // don't search image, but do search what it links against
                if ( sym != NULL ) {
                        CRSetCrashLogMessage(NULL);
                        result = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext , callerImage, false, underscoredName);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_NEXT, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
                const char* str = dyld::mkstringf("dlsym(RTLD_NEXT, %s): symbol not found", symbolName);
                dlerrorSet(str);
                free((void*)str);
                CRSetCrashLogMessage(NULL);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(RTLD_NEXT, %s) ==> NULL\n", __func__, symbolName);
                return NULL;
        }
        // magic "search me, then what I would see" handle
        else if ( handle == RTLD_SELF ) {
                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
#if SUPPORT_ACCELERATE_TABLES
                const mach_header* mh;
                const char* path;
                unsigned index;
                if ( dyld::addressInCache(callerAddress, &mh, &path, &index) ) {
                        // if dylib in cache is calling dlsym(RTLD_SELF,xxx) handle search differently
                        result = dyld::dlsymFromCache(RTLD_SELF, underscoredName, index);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_SELF, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
#endif
                ImageLoader* callerImage = dyld::findImageContainingAddress(callerAddress);
                sym = callerImage->findExportedSymbolInImageOrDependentImages(underscoredName, dyld::gLinkContext, &image); // search image and what it links against
                if ( sym != NULL ) {
                        CRSetCrashLogMessage(NULL);
                        result = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext, callerImage, false, underscoredName);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(RTLD_SELF, %s) ==> %p\n", __func__, symbolName, result);
                        return result;
                }
                const char* str = dyld::mkstringf("dlsym(RTLD_SELF, %s): symbol not found", symbolName);
                dlerrorSet(str);
                free((void*)str);
                CRSetCrashLogMessage(NULL);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(RTLD_SELF, %s) ==> NULL\n", __func__, symbolName);
                return NULL;
        }
#if SUPPORT_ACCELERATE_TABLES
        // check for mega dylib handle
        else if ( dyld::isCacheHandle(handle) ) {
                result = dyld::dlsymFromCache(handle, underscoredName, 0);
                if ( dyld::gLogAPIs )
                        dyld::log("  %s(%p, %s) ==> %p\n", __func__, handle, symbolName, result);
                return result;
        }
#endif
        // real handle
        image = (ImageLoader*)(((uintptr_t)handle) & (-4));     // clear mode bits
        if ( dyld::validImage(image) ) {
                if ( (((uintptr_t)handle) & 1) != 0 )
                        sym = image->findExportedSymbol(underscoredName, true, &image); // search RTLD_FIRST way
                else
                        sym = image->findExportedSymbolInImageOrDependentImages(underscoredName, dyld::gLinkContext, &image); // search image and what it links against
                
                if ( sym != NULL ) {
                        CRSetCrashLogMessage(NULL);
                        ImageLoader* callerImage = NULL;
                        if ( sDynamicInterposing ) {
                                // only take time to look up caller, if dynamic interposing in use
                                void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
                                callerImage = dyld::findImageContainingAddress(callerAddress);
                        }
                        result = (void*)image->getExportedSymbolAddress(sym, dyld::gLinkContext, callerImage, false, underscoredName);
                        if ( dyld::gLogAPIs )
                                dyld::log("  %s(%p, %s) ==> %p\n", __func__, handle, symbolName, result);
                        return result;
                }
                const char* str = dyld::mkstringf("dlsym(%p, %s): symbol not found", handle, symbolName);
                dlerrorSet(str);
                free((void*)str);
        }
        else {
                dlerrorSet("invalid handle passed to dlsym()");
        }
        CRSetCrashLogMessage(NULL);
        if ( dyld::gLogAPIs )
                dyld::log("  %s(%p, %s) ==> NULL\n", __func__, handle, symbolName);
        return NULL;
}










const struct dyld_all_image_infos* _dyld_get_all_image_infos()
{
        return dyld::gProcessInfo;
}


#if SUPPORT_ZERO_COST_EXCEPTIONS
static bool client_dyld_find_unwind_sections(void* addr, dyld_unwind_sections* info)
{
        //if ( dyld::gLogAPIs )
        //      dyld::log("%s(%p, %p)\n", __func__, addr, info);
        
#if SUPPORT_ACCELERATE_TABLES
        if ( dyld::findUnwindSections(addr, info) )
                return true;
#endif
        ImageLoader* image = dyld::findImageContainingAddress(addr);
        if ( image != NULL ) {
                image->getUnwindInfo(info);
                return true;
        }
        return false;
}
#endif


const char* dyld_image_path_containing_address(const void* address)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p)\n", __func__, address);

#if SUPPORT_ACCELERATE_TABLES
        const mach_header* mh;
        const char* path;
        if ( dyld::addressInCache(address, &mh, &path) )
                return path;
#endif

        ImageLoader* image = dyld::findImageContainingAddress(address);
        if ( image != NULL )
                return image->getRealPath();
        return NULL;
}



bool dyld_shared_cache_some_image_overridden()
{
 #if DYLD_SHARED_CACHE_SUPPORT
        return dyld::gSharedCacheOverridden;
 #else
    return true;
 #endif
}


void dyld_dynamic_interpose(const struct mach_header* mh, const struct dyld_interpose_tuple array[], size_t count)
{
        if ( mh == NULL )
                return;
        if ( array == NULL )
                return;
        if ( count == 0 )
                return;
        ImageLoader* image = dyld::findImageByMachHeader(mh);
        if ( image == NULL )
                return;
        
        // make pass at bound references in this image and update them
        dyld::gLinkContext.dynamicInterposeArray = array;
        dyld::gLinkContext.dynamicInterposeCount = count;
                image->dynamicInterpose(dyld::gLinkContext);
        dyld::gLinkContext.dynamicInterposeArray = NULL;
        dyld::gLinkContext.dynamicInterposeCount = 0;
        
        // leave interposing info so any future (lazy) binding will get it too
        image->addDynamicInterposingTuples(array, count);
        
        sDynamicInterposing = true;
}


bool _dyld_is_memory_immutable(const void* addr, size_t length)
{
        if ( dyld::gLogAPIs )
                dyld::log("%s(%p, %ld)\n", __func__, addr, length);

        uintptr_t checkStart = (uintptr_t)addr;
        uintptr_t checkEnd   = checkStart + length;

#if DYLD_SHARED_CACHE_SUPPORT
        // quick check to see if in r/o region of shared cache.  If so return true.
        if ( dyld_shared_cache_ranges.sharedRegionsCount > 2 ) {
                uintptr_t roStart    = dyld_shared_cache_ranges.ranges[0].start;
                uintptr_t roEnd      = roStart + dyld_shared_cache_ranges.ranges[0].length;
                if ( (roStart < checkStart) && (checkEnd < roEnd) )
                        return true;
        }
#endif

        // Otherwise find if addr is in a dyld loaded image
        ImageLoader* image = dyld::findImageContainingAddress(addr);
        if ( image != NULL ) {
                // <rdar://problem/24091154> already checked for r/o portion of cache
                if ( image->inSharedCache() )
                        return false;
                if ( !image->neverUnload() )
                        return false;
                for (unsigned i=0, e=image->segmentCount(); i < e; ++i) {
                        if ( (image->segActualLoadAddress(i) < checkStart) && (checkEnd < image->segActualEndAddress(i)) ) {
                                return !image->segWriteable(i);
                        }
                }
        }
        return false;
}



void _dyld_objc_notify_register(_dyld_objc_notify_mapped    mapped,
                                _dyld_objc_notify_init      init,
                                _dyld_objc_notify_unmapped  unmapped)
{
        dyld::registerObjCNotifiers(mapped, init, unmapped);
}


bool _dyld_get_shared_cache_uuid(uuid_t uuid)
{
        return dyld::sharedCacheUUID(uuid);
}