//===-- DynamicLoaderMacOSXDYLD.cpp -----------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/DataBuffer.h"
#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/State.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/ObjCLanguageRuntime.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
#include "lldb/Target/StackFrame.h"

#include "DynamicLoaderMacOSXDYLD.h"
#include "DynamicLoaderDarwin.h"

//#define ENABLE_DEBUG_PRINTF // COMMENT THIS LINE OUT PRIOR TO CHECKIN
#ifdef ENABLE_DEBUG_PRINTF
#include <stdio.h>
#define DEBUG_PRINTF(fmt, ...) printf(fmt, ## __VA_ARGS__)
#else
#define DEBUG_PRINTF(fmt, ...)
#endif

#ifndef __APPLE__
#include "Utility/UuidCompatibility.h"
#else
#include <uuid/uuid.h>
#endif

using namespace lldb;
using namespace lldb_private;


//----------------------------------------------------------------------
// Create an instance of this class. This function is filled into
// the plugin info class that gets handed out by the plugin factory and
// allows the lldb to instantiate an instance of this class.
//----------------------------------------------------------------------
DynamicLoader *
DynamicLoaderMacOSXDYLD::CreateInstance (Process* process, bool force)
{
    bool create = force;
    if (!create)
    {
        create = true;
        Module* exe_module = process->GetTarget().GetExecutableModulePointer();
        if (exe_module)
        {
            ObjectFile *object_file = exe_module->GetObjectFile();
            if (object_file)
            {
                create = (object_file->GetStrata() == ObjectFile::eStrataUser);
            }
        }
        
        if (create)
        {
            const llvm::Triple &triple_ref = process->GetTarget().GetArchitecture().GetTriple();
            switch (triple_ref.getOS())
            {
                case llvm::Triple::Darwin:
                case llvm::Triple::MacOSX:
                case llvm::Triple::IOS:
                case llvm::Triple::TvOS:
                case llvm::Triple::WatchOS:
                    create = triple_ref.getVendor() == llvm::Triple::Apple;
                    break;
                default:
                    create = false;
                    break;
            }
        }
    }
    
    if (create)
        return new DynamicLoaderMacOSXDYLD (process);
    return NULL;
}

//----------------------------------------------------------------------
// Constructor
//----------------------------------------------------------------------
DynamicLoaderMacOSXDYLD::DynamicLoaderMacOSXDYLD (Process* process) :
    DynamicLoaderDarwin(process),
    m_dyld_all_image_infos_addr(LLDB_INVALID_ADDRESS),
    m_dyld_all_image_infos(),
    m_dyld_all_image_infos_stop_id (UINT32_MAX),
    m_break_id(LLDB_INVALID_BREAK_ID),
    m_mutex(),
    m_process_image_addr_is_all_images_infos (false)
{
}

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
DynamicLoaderMacOSXDYLD::~DynamicLoaderMacOSXDYLD()
{
    if (LLDB_BREAK_ID_IS_VALID(m_break_id))
        m_process->GetTarget().RemoveBreakpointByID (m_break_id);
}

bool
DynamicLoaderMacOSXDYLD::ProcessDidExec ()
{
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    bool did_exec = false;
    if (m_process)
    {
        // If we are stopped after an exec, we will have only one thread...
        if (m_process->GetThreadList().GetSize() == 1)
        {
            // We know if a process has exec'ed if our "m_dyld_all_image_infos_addr"
            // value differs from the Process' image info address. When a process
            // execs itself it might cause a change if ASLR is enabled.
            const addr_t shlib_addr = m_process->GetImageInfoAddress ();
            if (m_process_image_addr_is_all_images_infos == true && shlib_addr != m_dyld_all_image_infos_addr)
            {
                // The image info address from the process is the 'dyld_all_image_infos'
                // address and it has changed.
                did_exec = true;
            }
            else if (m_process_image_addr_is_all_images_infos == false && shlib_addr == m_dyld.address)
            {
                // The image info address from the process is the mach_header
                // address for dyld and it has changed.
                did_exec = true;
            }
            else
            {
                // ASLR might be disabled and dyld could have ended up in the same
                // location. We should try and detect if we are stopped at '_dyld_start'
                ThreadSP thread_sp(m_process->GetThreadList().GetThreadAtIndex(0));
                if (thread_sp)
                {
                    lldb::StackFrameSP frame_sp(thread_sp->GetStackFrameAtIndex(0));
                    if (frame_sp)
                    {
                        const Symbol *symbol = frame_sp->GetSymbolContext(eSymbolContextSymbol).symbol;
                        if (symbol)
                        {
                            if (symbol->GetName() == ConstString("_dyld_start"))
                                did_exec = true;
                        }
                    }
                }
            }

            if (did_exec)
            {
                m_libpthread_module_wp.reset();
                m_pthread_getspecific_addr.Clear();
            }
        }
    }
    return did_exec;
}

//----------------------------------------------------------------------
// Clear out the state of this class.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::DoClear ()
{
    std::lock_guard<std::recursive_mutex> guard(m_mutex);

    if (LLDB_BREAK_ID_IS_VALID(m_break_id))
        m_process->GetTarget().RemoveBreakpointByID (m_break_id);

    m_dyld_all_image_infos_addr = LLDB_INVALID_ADDRESS;
    m_dyld_all_image_infos.Clear();
    m_break_id = LLDB_INVALID_BREAK_ID;
}

//----------------------------------------------------------------------
// Check if we have found DYLD yet
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::DidSetNotificationBreakpoint()
{
    return LLDB_BREAK_ID_IS_VALID (m_break_id);
}

void
DynamicLoaderMacOSXDYLD::ClearNotificationBreakpoint ()
{
    if (LLDB_BREAK_ID_IS_VALID (m_break_id))
    {
        m_process->GetTarget().RemoveBreakpointByID (m_break_id);
    }
}

//----------------------------------------------------------------------
// Try and figure out where dyld is by first asking the Process
// if it knows (which currently calls down in the lldb::Process
// to get the DYLD info (available on SnowLeopard only). If that fails,
// then check in the default addresses.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::DoInitialImageFetch()
{
    if (m_dyld_all_image_infos_addr == LLDB_INVALID_ADDRESS)
    {
        // Check the image info addr as it might point to the 
        // mach header for dyld, or it might point to the 
        // dyld_all_image_infos struct
        const addr_t shlib_addr = m_process->GetImageInfoAddress ();
        if (shlib_addr != LLDB_INVALID_ADDRESS)
        {
            ByteOrder byte_order = m_process->GetTarget().GetArchitecture().GetByteOrder();
            uint8_t buf[4];
            DataExtractor data (buf, sizeof(buf), byte_order, 4);
            Error error;
            if (m_process->ReadMemory (shlib_addr, buf, 4, error) == 4)
            {
                lldb::offset_t offset = 0;
                uint32_t magic = data.GetU32 (&offset);
                switch (magic)
                {
                case llvm::MachO::MH_MAGIC:
                case llvm::MachO::MH_MAGIC_64:
                case llvm::MachO::MH_CIGAM:
                case llvm::MachO::MH_CIGAM_64:
                    m_process_image_addr_is_all_images_infos = false;
                    ReadDYLDInfoFromMemoryAndSetNotificationCallback(shlib_addr);
                    return;
                    
                default:
                    break;
                }
            }
            // Maybe it points to the all image infos?
            m_dyld_all_image_infos_addr = shlib_addr;
            m_process_image_addr_is_all_images_infos = true;
        }
    }

    if (m_dyld_all_image_infos_addr != LLDB_INVALID_ADDRESS)
    {
        if (ReadAllImageInfosStructure ())
        {
            if (m_dyld_all_image_infos.dyldImageLoadAddress != LLDB_INVALID_ADDRESS)
                ReadDYLDInfoFromMemoryAndSetNotificationCallback (m_dyld_all_image_infos.dyldImageLoadAddress);
            else
                ReadDYLDInfoFromMemoryAndSetNotificationCallback (m_dyld_all_image_infos_addr & 0xfffffffffff00000ull);
            return;
        }
    }

    // Check some default values
    Module *executable = m_process->GetTarget().GetExecutableModulePointer();

    if (executable)
    {
        const ArchSpec &exe_arch = executable->GetArchitecture();
        if (exe_arch.GetAddressByteSize() == 8)
        {
            ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x7fff5fc00000ull);
        }
        else if (exe_arch.GetMachine() == llvm::Triple::arm || exe_arch.GetMachine() == llvm::Triple::thumb || exe_arch.GetMachine() == llvm::Triple::aarch64)
        {
            ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x2fe00000);
        }
        else
        {
            ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x8fe00000);
        }
    }
    return;
}

//----------------------------------------------------------------------
// Assume that dyld is in memory at ADDR and try to parse it's load
// commands
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::ReadDYLDInfoFromMemoryAndSetNotificationCallback(lldb::addr_t addr)
{
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    DataExtractor data; // Load command data
    if (ReadMachHeader (addr, &m_dyld.header, &data))
    {
        if (m_dyld.header.filetype == llvm::MachO::MH_DYLINKER)
        {
            m_dyld.address = addr;
            ModuleSP dyld_module_sp;
            if (ParseLoadCommands (data, m_dyld, &m_dyld.file_spec))
            {
                if (m_dyld.file_spec)
                {
                    UpdateDYLDImageInfoFromNewImageInfo (m_dyld);

                }
            }
            dyld_module_sp = GetDYLDModule();

            Target &target = m_process->GetTarget();

            if (m_dyld_all_image_infos_addr == LLDB_INVALID_ADDRESS && dyld_module_sp.get())
            {
                static ConstString g_dyld_all_image_infos ("dyld_all_image_infos");
                const Symbol *symbol = dyld_module_sp->FindFirstSymbolWithNameAndType (g_dyld_all_image_infos, eSymbolTypeData);
                if (symbol)
                    m_dyld_all_image_infos_addr = symbol->GetLoadAddress(&target);
            }

            // Update all image infos
            InitializeFromAllImageInfos ();

            // If we didn't have an executable before, but now we do, then the
            // dyld module shared pointer might be unique and we may need to add
            // it again (since Target::SetExecutableModule() will clear the
            // images). So append the dyld module back to the list if it is
            /// unique!
            if (dyld_module_sp)
            {
                target.GetImages().AppendIfNeeded (dyld_module_sp);

                // At this point we should have read in dyld's module, and so we should set breakpoints in it:
                ModuleList modules;
                modules.Append(dyld_module_sp);
                target.ModulesDidLoad(modules);
                SetDYLDModule (dyld_module_sp);
            }
            return true;
        }
    }
    return false;
}

bool
DynamicLoaderMacOSXDYLD::NeedToDoInitialImageFetch ()
{
    return m_dyld_all_image_infos_addr == LLDB_INVALID_ADDRESS;
}

//----------------------------------------------------------------------
// Static callback function that gets called when our DYLD notification
// breakpoint gets hit. We update all of our image infos and then
// let our super class DynamicLoader class decide if we should stop
// or not (based on global preference).
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::NotifyBreakpointHit (void *baton, 
                                              StoppointCallbackContext *context, 
                                              lldb::user_id_t break_id, 
                                              lldb::user_id_t break_loc_id)
{
    // Let the event know that the images have changed
    // DYLD passes three arguments to the notification breakpoint.
    // Arg1: enum dyld_image_mode mode - 0 = adding, 1 = removing 
    // Arg2: uint32_t infoCount        - Number of shared libraries added  
    // Arg3: dyld_image_info info[]    - Array of structs of the form:
    //                                     const struct mach_header *imageLoadAddress
    //                                     const char               *imageFilePath
    //                                     uintptr_t                 imageFileModDate (a time_t)
    
    DynamicLoaderMacOSXDYLD* dyld_instance = (DynamicLoaderMacOSXDYLD*) baton;
    
    // First step is to see if we've already initialized the all image infos.  If we haven't then this function
    // will do so and return true.  In the course of initializing the all_image_infos it will read the complete
    // current state, so we don't need to figure out what has changed from the data passed in to us.
    
    ExecutionContext exe_ctx (context->exe_ctx_ref);
    Process *process = exe_ctx.GetProcessPtr();

    // This is a sanity check just in case this dyld_instance is an old dyld plugin's breakpoint still lying around.
    if (process != dyld_instance->m_process)
        return false;

    if (dyld_instance->InitializeFromAllImageInfos())
        return dyld_instance->GetStopWhenImagesChange(); 

    const lldb::ABISP &abi = process->GetABI();
    if (abi)
    {
        // Build up the value array to store the three arguments given above, then get the values from the ABI:
        
        ClangASTContext *clang_ast_context = process->GetTarget().GetScratchClangASTContext();
        ValueList argument_values;
        Value input_value;
        
        CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
        CompilerType clang_uint32_type = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(lldb::eEncodingUint, 32);
        input_value.SetValueType (Value::eValueTypeScalar);
        input_value.SetCompilerType (clang_uint32_type);
//        input_value.SetContext (Value::eContextTypeClangType, clang_uint32_type);
        argument_values.PushValue (input_value);
        argument_values.PushValue (input_value);
        input_value.SetCompilerType (clang_void_ptr_type);
        //        input_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type);
        argument_values.PushValue (input_value);
        
        if (abi->GetArgumentValues (exe_ctx.GetThreadRef(), argument_values))
        {
            uint32_t dyld_mode = argument_values.GetValueAtIndex(0)->GetScalar().UInt (-1);
            if (dyld_mode != static_cast<uint32_t>(-1))
            {
                // Okay the mode was right, now get the number of elements, and the array of new elements...
                uint32_t image_infos_count = argument_values.GetValueAtIndex(1)->GetScalar().UInt (-1);
                if (image_infos_count != static_cast<uint32_t>(-1))
                {
                    // Got the number added, now go through the array of added elements, putting out the mach header 
                    // address, and adding the image.
                    // Note, I'm not putting in logging here, since the AddModules & RemoveModules functions do
                    // all the logging internally.
                    
                    lldb::addr_t image_infos_addr = argument_values.GetValueAtIndex(2)->GetScalar().ULongLong();
                    if (dyld_mode == 0)
                    {
                        // This is add:
                        dyld_instance->AddModulesUsingImageInfosAddress (image_infos_addr, image_infos_count);
                    }
                    else
                    {
                        // This is remove:
                        dyld_instance->RemoveModulesUsingImageInfosAddress (image_infos_addr, image_infos_count);
                    }
                    
                }
            }
        }
    }
    else
    {
        process->GetTarget().GetDebugger().GetAsyncErrorStream()->Printf("No ABI plugin located for triple %s -- shared libraries will not be registered!\n", process->GetTarget().GetArchitecture().GetTriple().getTriple().c_str());
    }
    
    // Return true to stop the target, false to just let the target run
    return dyld_instance->GetStopWhenImagesChange();
}

bool
DynamicLoaderMacOSXDYLD::ReadAllImageInfosStructure ()
{
    std::lock_guard<std::recursive_mutex> guard(m_mutex);

    // the all image infos is already valid for this process stop ID
    if (m_process->GetStopID() == m_dyld_all_image_infos_stop_id)
        return true;

    m_dyld_all_image_infos.Clear();
    if (m_dyld_all_image_infos_addr != LLDB_INVALID_ADDRESS)
    {
        ByteOrder byte_order = m_process->GetTarget().GetArchitecture().GetByteOrder();
        uint32_t addr_size = 4;
        if (m_dyld_all_image_infos_addr > UINT32_MAX)
            addr_size = 8;

        uint8_t buf[256];
        DataExtractor data (buf, sizeof(buf), byte_order, addr_size);
        lldb::offset_t offset = 0;

        const size_t count_v2 =  sizeof (uint32_t) + // version
                                 sizeof (uint32_t) + // infoArrayCount
                                 addr_size +         // infoArray
                                 addr_size +         // notification
                                 addr_size +         // processDetachedFromSharedRegion + libSystemInitialized + pad
                                 addr_size;          // dyldImageLoadAddress
        const size_t count_v11 = count_v2 +
                                 addr_size +         // jitInfo
                                 addr_size +         // dyldVersion
                                 addr_size +         // errorMessage
                                 addr_size +         // terminationFlags
                                 addr_size +         // coreSymbolicationShmPage
                                 addr_size +         // systemOrderFlag
                                 addr_size +         // uuidArrayCount
                                 addr_size +         // uuidArray
                                 addr_size +         // dyldAllImageInfosAddress
                                 addr_size +         // initialImageCount
                                 addr_size +         // errorKind
                                 addr_size +         // errorClientOfDylibPath
                                 addr_size +         // errorTargetDylibPath
                                 addr_size;          // errorSymbol
        const size_t count_v13 = count_v11 +
                                 addr_size +         // sharedCacheSlide
                                 sizeof (uuid_t);    // sharedCacheUUID
        UNUSED_IF_ASSERT_DISABLED(count_v13);
        assert (sizeof (buf) >= count_v13);

        Error error;
        if (m_process->ReadMemory (m_dyld_all_image_infos_addr, buf, 4, error) == 4)
        {
            m_dyld_all_image_infos.version = data.GetU32(&offset);
            // If anything in the high byte is set, we probably got the byte 
            // order incorrect (the process might not have it set correctly 
            // yet due to attaching to a program without a specified file).
            if (m_dyld_all_image_infos.version & 0xff000000)
            {
                // We have guessed the wrong byte order. Swap it and try
                // reading the version again.
                if (byte_order == eByteOrderLittle)
                    byte_order = eByteOrderBig;
                else
                    byte_order = eByteOrderLittle;

                data.SetByteOrder (byte_order);
                offset = 0;
                m_dyld_all_image_infos.version = data.GetU32(&offset);
            }
        }
        else
        {
            return false;
        }

        const size_t count = (m_dyld_all_image_infos.version >= 11) ? count_v11 : count_v2;

        const size_t bytes_read = m_process->ReadMemory (m_dyld_all_image_infos_addr, buf, count, error);
        if (bytes_read == count)
        {
            offset = 0;
            m_dyld_all_image_infos.version = data.GetU32(&offset);
            m_dyld_all_image_infos.dylib_info_count = data.GetU32(&offset);
            m_dyld_all_image_infos.dylib_info_addr = data.GetPointer(&offset);
            m_dyld_all_image_infos.notification = data.GetPointer(&offset);
            m_dyld_all_image_infos.processDetachedFromSharedRegion = data.GetU8(&offset);
            m_dyld_all_image_infos.libSystemInitialized = data.GetU8(&offset);
            // Adjust for padding.
            offset += addr_size - 2;
            m_dyld_all_image_infos.dyldImageLoadAddress = data.GetPointer(&offset);
            if (m_dyld_all_image_infos.version >= 11)
            {
                offset += addr_size * 8;
                uint64_t dyld_all_image_infos_addr = data.GetPointer(&offset);

                // When we started, we were given the actual address of the all_image_infos
                // struct (probably via TASK_DYLD_INFO) in memory - this address is stored in
                // m_dyld_all_image_infos_addr and is the most accurate address we have.

                // We read the dyld_all_image_infos struct from memory; it contains its own address.
                // If the address in the struct does not match the actual address,
                // the dyld we're looking at has been loaded at a different location (slid) from
                // where it intended to load.  The addresses in the dyld_all_image_infos struct
                // are the original, non-slid addresses, and need to be adjusted.  Most importantly
                // the address of dyld and the notification address need to be adjusted.

                if (dyld_all_image_infos_addr != m_dyld_all_image_infos_addr)
                {
                    uint64_t image_infos_offset = dyld_all_image_infos_addr - m_dyld_all_image_infos.dyldImageLoadAddress;
                    uint64_t notification_offset = m_dyld_all_image_infos.notification - m_dyld_all_image_infos.dyldImageLoadAddress;
                    m_dyld_all_image_infos.dyldImageLoadAddress = m_dyld_all_image_infos_addr - image_infos_offset;
                    m_dyld_all_image_infos.notification = m_dyld_all_image_infos.dyldImageLoadAddress + notification_offset;
                }
            }
            m_dyld_all_image_infos_stop_id = m_process->GetStopID();
            return true;
        }
    }
    return false;
}


bool
DynamicLoaderMacOSXDYLD::AddModulesUsingImageInfosAddress (lldb::addr_t image_infos_addr, uint32_t image_infos_count)
{
    ImageInfo::collection image_infos;
    Log *log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_DYNAMIC_LOADER));
    if (log)
        log->Printf ("Adding %d modules.\n", image_infos_count);
        
    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    if (m_process->GetStopID() == m_dyld_image_infos_stop_id)
        return true;

    StructuredData::ObjectSP image_infos_json_sp = m_process->GetLoadedDynamicLibrariesInfos (image_infos_addr, image_infos_count);
    if (image_infos_json_sp.get() 
        && image_infos_json_sp->GetAsDictionary() 
        && image_infos_json_sp->GetAsDictionary()->HasKey("images")
        && image_infos_json_sp->GetAsDictionary()->GetValueForKey("images")->GetAsArray()
        && image_infos_json_sp->GetAsDictionary()->GetValueForKey("images")->GetAsArray()->GetSize() == image_infos_count)
    {
        bool return_value = false;
        if (JSONImageInformationIntoImageInfo (image_infos_json_sp, image_infos))
        {
            AddExecutableModuleIfInImageInfos (image_infos);
            return_value = AddModulesUsingImageInfos (image_infos);
        }
        m_dyld_image_infos_stop_id = m_process->GetStopID();
        return return_value;
    }

    if (!ReadImageInfos (image_infos_addr, image_infos_count, image_infos))
        return false;
        
    UpdateImageInfosHeaderAndLoadCommands (image_infos, image_infos_count, false);
    bool return_value = AddModulesUsingImageInfos (image_infos);
    m_dyld_image_infos_stop_id = m_process->GetStopID();
    return return_value;
}

bool
DynamicLoaderMacOSXDYLD::RemoveModulesUsingImageInfosAddress (lldb::addr_t image_infos_addr, uint32_t image_infos_count)
{
    ImageInfo::collection image_infos;
    Log *log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_DYNAMIC_LOADER));
    
    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    if (m_process->GetStopID() == m_dyld_image_infos_stop_id)
        return true;

    // First read in the image_infos for the removed modules, and their headers & load commands.
    if (!ReadImageInfos (image_infos_addr, image_infos_count, image_infos))
    {
        if (log)
            log->PutCString ("Failed reading image infos array.");
        return false;
    }
    
    if (log)
        log->Printf ("Removing %d modules.", image_infos_count);
    
    ModuleList unloaded_module_list;
    for (uint32_t idx = 0; idx < image_infos.size(); ++idx)
    {        
        if (log)
        {
            log->Printf ("Removing module at address=0x%16.16" PRIx64 ".", image_infos[idx].address);
            image_infos[idx].PutToLog (log);
        }
            
        // Remove this image_infos from the m_all_image_infos.  We do the comparison by address
        // rather than by file spec because we can have many modules with the same "file spec" in the
        // case that they are modules loaded from memory.
        //
        // Also copy over the uuid from the old entry to the removed entry so we can 
        // use it to lookup the module in the module list.
        
        ImageInfo::collection::iterator pos, end = m_dyld_image_infos.end();
        for (pos = m_dyld_image_infos.begin(); pos != end; pos++)
        {
            if (image_infos[idx].address == (*pos).address)
            {
                image_infos[idx].uuid = (*pos).uuid;

                // Add the module from this image_info to the "unloaded_module_list".  We'll remove them all at
                // one go later on.
                
                ModuleSP unload_image_module_sp (FindTargetModuleForImageInfo (image_infos[idx], false, NULL));
                if (unload_image_module_sp.get())
                {
                    // When we unload, be sure to use the image info from the old list,
                    // since that has sections correctly filled in.
                    UnloadModuleSections (unload_image_module_sp.get(), *pos);
                    unloaded_module_list.AppendIfNeeded (unload_image_module_sp);
                }
                else
                {
                    if (log)
                    {
                        log->Printf ("Could not find module for unloading info entry:");
                        image_infos[idx].PutToLog(log);
                    }
                }
                
                // Then remove it from the m_dyld_image_infos:
                
                m_dyld_image_infos.erase(pos);
                break;
            }
        }
        
        if (pos == end)
        {
            if (log)
            {
                log->Printf ("Could not find image_info entry for unloading image:");
                image_infos[idx].PutToLog(log);
            }
        }
    }
    if (unloaded_module_list.GetSize() > 0)
    {
        if (log)
        {
            log->PutCString("Unloaded:");
            unloaded_module_list.LogUUIDAndPaths (log, "DynamicLoaderMacOSXDYLD::ModulesDidUnload");
        }
        m_process->GetTarget().GetImages().Remove (unloaded_module_list);
    }
    m_dyld_image_infos_stop_id = m_process->GetStopID();
    return true;
}

bool
DynamicLoaderMacOSXDYLD::ReadImageInfos (lldb::addr_t image_infos_addr, 
                                         uint32_t image_infos_count, 
                                         ImageInfo::collection &image_infos)
{
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    const ByteOrder endian = GetByteOrderFromMagic (m_dyld.header.magic);
    const uint32_t addr_size = m_dyld.GetAddressByteSize();

    image_infos.resize(image_infos_count);
    const size_t count = image_infos.size() * 3 * addr_size;
    DataBufferHeap info_data(count, 0);
    Error error;
    const size_t bytes_read = m_process->ReadMemory (image_infos_addr, 
                                                     info_data.GetBytes(), 
                                                     info_data.GetByteSize(),
                                                     error);
    if (bytes_read == count)
    {
        lldb::offset_t info_data_offset = 0;
        DataExtractor info_data_ref(info_data.GetBytes(), info_data.GetByteSize(), endian, addr_size);
        for (size_t i = 0; i < image_infos.size() && info_data_ref.ValidOffset(info_data_offset); i++)
        {
            image_infos[i].address = info_data_ref.GetPointer(&info_data_offset);
            lldb::addr_t path_addr = info_data_ref.GetPointer(&info_data_offset);
            image_infos[i].mod_date = info_data_ref.GetPointer(&info_data_offset);

            char raw_path[PATH_MAX];
            m_process->ReadCStringFromMemory (path_addr, raw_path, sizeof(raw_path), error);
            // don't resolve the path
            if (error.Success())
            {
                const bool resolve_path = false;
                image_infos[i].file_spec.SetFile(raw_path, resolve_path);
            }
        }
        return true;
    }
    else
    {
        return false;
    }
}

//----------------------------------------------------------------------
// If we have found where the "_dyld_all_image_infos" lives in memory,
// read the current info from it, and then update all image load
// addresses (or lack thereof).  Only do this if this is the first time
// we're reading the dyld infos.  Return true if we actually read anything,
// and false otherwise.
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::InitializeFromAllImageInfos ()
{
    Log *log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_DYNAMIC_LOADER));
    
    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    if (m_process->GetStopID() == m_dyld_image_infos_stop_id
          || m_dyld_image_infos.size() != 0)
        return false;

    if (ReadAllImageInfosStructure ())
    {
        // Nothing to load or unload?
        if (m_dyld_all_image_infos.dylib_info_count == 0)
            return true;
        
        if (m_dyld_all_image_infos.dylib_info_addr == 0)
        {
            // DYLD is updating the images now.  So we should say we have no images, and then we'll 
            // figure it out when we hit the added breakpoint.
            return false;
        }
        else
        {
            if (!AddModulesUsingImageInfosAddress (m_dyld_all_image_infos.dylib_info_addr, 
                                                   m_dyld_all_image_infos.dylib_info_count))
            {
                DEBUG_PRINTF("%s", "unable to read all data for all_dylib_infos.");
                m_dyld_image_infos.clear();
            }
        }

        // Now we have one more bit of business.  If there is a library left in the images for our target that
        // doesn't have a load address, then it must be something that we were expecting to load (for instance we
        // read a load command for it) but it didn't in fact load - probably because DYLD_*_PATH pointed
        // to an equivalent version.  We don't want it to stay in the target's module list or it will confuse
        // us, so unload it here.
        Target &target = m_process->GetTarget();
        const ModuleList &target_modules = target.GetImages();
        ModuleList not_loaded_modules;
        std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex());
        
        size_t num_modules = target_modules.GetSize();
        for (size_t i = 0; i < num_modules; i++)
        {
            ModuleSP module_sp = target_modules.GetModuleAtIndexUnlocked (i);
            if (!module_sp->IsLoadedInTarget (&target))
            {
                if (log)
                {
                    StreamString s;
                    module_sp->GetDescription (&s);
                    log->Printf ("Unloading pre-run module: %s.", s.GetData ());
                }
                not_loaded_modules.Append (module_sp);
            }
        }
        
        if (not_loaded_modules.GetSize() != 0)
        {
            target.GetImages().Remove(not_loaded_modules);
        }

        return true;
    }
    else
        return false;
}

//----------------------------------------------------------------------
// Read a mach_header at ADDR into HEADER, and also fill in the load
// command data into LOAD_COMMAND_DATA if it is non-NULL.
//
// Returns true if we succeed, false if we fail for any reason.
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::ReadMachHeader (lldb::addr_t addr, llvm::MachO::mach_header *header, DataExtractor *load_command_data)
{
    DataBufferHeap header_bytes(sizeof(llvm::MachO::mach_header), 0);
    Error error;
    size_t bytes_read = m_process->ReadMemory (addr, 
                                               header_bytes.GetBytes(), 
                                               header_bytes.GetByteSize(), 
                                               error);
    if (bytes_read == sizeof(llvm::MachO::mach_header))
    {
        lldb::offset_t offset = 0;
        ::memset (header, 0, sizeof(llvm::MachO::mach_header));

        // Get the magic byte unswapped so we can figure out what we are dealing with
        DataExtractor data(header_bytes.GetBytes(), header_bytes.GetByteSize(), endian::InlHostByteOrder(), 4);
        header->magic = data.GetU32(&offset);
        lldb::addr_t load_cmd_addr = addr;
        data.SetByteOrder(DynamicLoaderMacOSXDYLD::GetByteOrderFromMagic(header->magic));
        switch (header->magic)
        {
        case llvm::MachO::MH_MAGIC:
        case llvm::MachO::MH_CIGAM:
            data.SetAddressByteSize(4);
            load_cmd_addr += sizeof(llvm::MachO::mach_header);
            break;

        case llvm::MachO::MH_MAGIC_64:
        case llvm::MachO::MH_CIGAM_64:
            data.SetAddressByteSize(8);
            load_cmd_addr += sizeof(llvm::MachO::mach_header_64);
            break;

        default:
            return false;
        }

        // Read the rest of dyld's mach header
        if (data.GetU32(&offset, &header->cputype, (sizeof(llvm::MachO::mach_header)/sizeof(uint32_t)) - 1))
        {
            if (load_command_data == NULL)
                return true; // We were able to read the mach_header and weren't asked to read the load command bytes

            DataBufferSP load_cmd_data_sp(new DataBufferHeap(header->sizeofcmds, 0));

            size_t load_cmd_bytes_read = m_process->ReadMemory (load_cmd_addr, 
                                                                load_cmd_data_sp->GetBytes(), 
                                                                load_cmd_data_sp->GetByteSize(),
                                                                error);
            
            if (load_cmd_bytes_read == header->sizeofcmds)
            {
                // Set the load command data and also set the correct endian
                // swap settings and the correct address size
                load_command_data->SetData(load_cmd_data_sp, 0, header->sizeofcmds);
                load_command_data->SetByteOrder(data.GetByteOrder());
                load_command_data->SetAddressByteSize(data.GetAddressByteSize());
                return true; // We successfully read the mach_header and the load command data
            }

            return false; // We weren't able to read the load command data
        }
    }
    return false; // We failed the read the mach_header
}


//----------------------------------------------------------------------
// Parse the load commands for an image
//----------------------------------------------------------------------
uint32_t
DynamicLoaderMacOSXDYLD::ParseLoadCommands (const DataExtractor& data, ImageInfo& dylib_info, FileSpec *lc_id_dylinker)
{
    lldb::offset_t offset = 0;
    uint32_t cmd_idx;
    Segment segment;
    dylib_info.Clear (true);

    for (cmd_idx = 0; cmd_idx < dylib_info.header.ncmds; cmd_idx++)
    {
        // Clear out any load command specific data from DYLIB_INFO since
        // we are about to read it.

        if (data.ValidOffsetForDataOfSize (offset, sizeof(llvm::MachO::load_command)))
        {
            llvm::MachO::load_command load_cmd;
            lldb::offset_t load_cmd_offset = offset;
            load_cmd.cmd = data.GetU32 (&offset);
            load_cmd.cmdsize = data.GetU32 (&offset);
            switch (load_cmd.cmd)
            {
            case llvm::MachO::LC_SEGMENT:
                {
                    segment.name.SetTrimmedCStringWithLength ((const char *)data.GetData(&offset, 16), 16);
                    // We are putting 4 uint32_t values 4 uint64_t values so
                    // we have to use multiple 32 bit gets below.
                    segment.vmaddr = data.GetU32 (&offset);
                    segment.vmsize = data.GetU32 (&offset);
                    segment.fileoff = data.GetU32 (&offset);
                    segment.filesize = data.GetU32 (&offset);
                    // Extract maxprot, initprot, nsects and flags all at once
                    data.GetU32(&offset, &segment.maxprot, 4);
                    dylib_info.segments.push_back (segment);
                }
                break;

            case llvm::MachO::LC_SEGMENT_64:
                {
                    segment.name.SetTrimmedCStringWithLength ((const char *)data.GetData(&offset, 16), 16);
                    // Extract vmaddr, vmsize, fileoff, and filesize all at once
                    data.GetU64(&offset, &segment.vmaddr, 4);
                    // Extract maxprot, initprot, nsects and flags all at once
                    data.GetU32(&offset, &segment.maxprot, 4);
                    dylib_info.segments.push_back (segment);
                }
                break;

            case llvm::MachO::LC_ID_DYLINKER:
                if (lc_id_dylinker)
                {
                    const lldb::offset_t name_offset = load_cmd_offset + data.GetU32 (&offset);
                    const char *path = data.PeekCStr (name_offset);
                    lc_id_dylinker->SetFile (path, true);
                }
                break;

            case llvm::MachO::LC_UUID:
                dylib_info.uuid.SetBytes(data.GetData (&offset, 16));
                break;

            default:
                break;
            }
            // Set offset to be the beginning of the next load command.
            offset = load_cmd_offset + load_cmd.cmdsize;
        }
    }
    
    // All sections listed in the dyld image info structure will all
    // either be fixed up already, or they will all be off by a single
    // slide amount that is determined by finding the first segment
    // that is at file offset zero which also has bytes (a file size
    // that is greater than zero) in the object file.
    
    // Determine the slide amount (if any)
    const size_t num_sections = dylib_info.segments.size();
    for (size_t i = 0; i < num_sections; ++i)
    {
        // Iterate through the object file sections to find the
        // first section that starts of file offset zero and that
        // has bytes in the file...
        if ((dylib_info.segments[i].fileoff == 0 && dylib_info.segments[i].filesize > 0) || (dylib_info.segments[i].name == ConstString("__TEXT")))
        {
            dylib_info.slide = dylib_info.address - dylib_info.segments[i].vmaddr;
            // We have found the slide amount, so we can exit
            // this for loop.
            break;
        }
    }
    return cmd_idx;
}

//----------------------------------------------------------------------
// Read the mach_header and load commands for each image that the
// _dyld_all_image_infos structure points to and cache the results.
//----------------------------------------------------------------------

void
DynamicLoaderMacOSXDYLD::UpdateImageInfosHeaderAndLoadCommands(ImageInfo::collection &image_infos, 
                                                               uint32_t infos_count, 
                                                               bool update_executable)
{
    uint32_t exe_idx = UINT32_MAX;
    // Read any UUID values that we can get
    for (uint32_t i = 0; i < infos_count; i++)
    {
        if (!image_infos[i].UUIDValid())
        {
            DataExtractor data; // Load command data
            if (!ReadMachHeader (image_infos[i].address, &image_infos[i].header, &data))
                continue;

            ParseLoadCommands (data, image_infos[i], NULL);

            if (image_infos[i].header.filetype == llvm::MachO::MH_EXECUTE)
                exe_idx = i;
            
        }
    }

    Target &target = m_process->GetTarget();

    if (exe_idx < image_infos.size())
    {
        const bool can_create = true;
        ModuleSP exe_module_sp (FindTargetModuleForImageInfo (image_infos[exe_idx], can_create, NULL));

        if (exe_module_sp)
        {
            UpdateImageLoadAddress (exe_module_sp.get(), image_infos[exe_idx]);

            if (exe_module_sp.get() != target.GetExecutableModulePointer())
            {
                // Don't load dependent images since we are in dyld where we will know
                // and find out about all images that are loaded. Also when setting the
                // executable module, it will clear the targets module list, and if we
                // have an in memory dyld module, it will get removed from the list
                // so we will need to add it back after setting the executable module,
                // so we first try and see if we already have a weak pointer to the
                // dyld module, make it into a shared pointer, then add the executable,
                // then re-add it back to make sure it is always in the list.
                ModuleSP dyld_module_sp(GetDYLDModule ());
                
                const bool get_dependent_images = false;
                m_process->GetTarget().SetExecutableModule (exe_module_sp, 
                                                            get_dependent_images);

                if (dyld_module_sp)
                {
                   if(target.GetImages().AppendIfNeeded (dyld_module_sp))
                   {
                        std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());

                        // Also add it to the section list.
                        UpdateImageLoadAddress(dyld_module_sp.get(), m_dyld);
                   }
                }
            }
        }
    }
}


//----------------------------------------------------------------------
// Dump the _dyld_all_image_infos members and all current image infos
// that we have parsed to the file handle provided.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::PutToLog(Log *log) const
{
    if (log == NULL)
        return;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
    log->Printf("dyld_all_image_infos = { version=%d, count=%d, addr=0x%8.8" PRIx64 ", notify=0x%8.8" PRIx64 " }",
                    m_dyld_all_image_infos.version,
                    m_dyld_all_image_infos.dylib_info_count,
                    (uint64_t)m_dyld_all_image_infos.dylib_info_addr,
                    (uint64_t)m_dyld_all_image_infos.notification);
    size_t i;
    const size_t count = m_dyld_image_infos.size();
    if (count > 0)
    {
        log->PutCString("Loaded:");
        for (i = 0; i<count; i++)
            m_dyld_image_infos[i].PutToLog(log);
    }
}

bool
DynamicLoaderMacOSXDYLD::SetNotificationBreakpoint ()
{
    DEBUG_PRINTF("DynamicLoaderMacOSXDYLD::%s() process state = %s\n", __FUNCTION__, StateAsCString(m_process->GetState()));
    if (m_break_id == LLDB_INVALID_BREAK_ID)
    {
        if (m_dyld_all_image_infos.notification != LLDB_INVALID_ADDRESS)
        {
            Address so_addr;
            // Set the notification breakpoint and install a breakpoint
            // callback function that will get called each time the
            // breakpoint gets hit. We will use this to track when shared
            // libraries get loaded/unloaded.
            bool resolved = m_process->GetTarget().ResolveLoadAddress(m_dyld_all_image_infos.notification, so_addr);
            if (!resolved)
            {
                ModuleSP dyld_module_sp = m_dyld_module_wp.lock();
                if (dyld_module_sp)
                {
                    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());

                    UpdateImageLoadAddress (dyld_module_sp.get(), m_dyld);
                    resolved = m_process->GetTarget().ResolveLoadAddress(m_dyld_all_image_infos.notification, so_addr);
                }
            }

            if (resolved)
            {
                Breakpoint *dyld_break = m_process->GetTarget().CreateBreakpoint (so_addr, true, false).get();
                dyld_break->SetCallback (DynamicLoaderMacOSXDYLD::NotifyBreakpointHit, this, true);
                dyld_break->SetBreakpointKind ("shared-library-event");
                m_break_id = dyld_break->GetID();
            }
        }
    }
    return m_break_id != LLDB_INVALID_BREAK_ID;
}

Error
DynamicLoaderMacOSXDYLD::CanLoadImage ()
{
    Error error;
    // In order for us to tell if we can load a shared library we verify that
    // the dylib_info_addr isn't zero (which means no shared libraries have
    // been set yet, or dyld is currently mucking with the shared library list).
    if (ReadAllImageInfosStructure ())
    {
        // TODO: also check the _dyld_global_lock_held variable in libSystem.B.dylib?
        // TODO: check the malloc lock?
        // TODO: check the objective C lock?
        if (m_dyld_all_image_infos.dylib_info_addr != 0)
            return error; // Success
    }

    error.SetErrorString("unsafe to load or unload shared libraries");
    return error;
}

void
DynamicLoaderMacOSXDYLD::Initialize()
{
    PluginManager::RegisterPlugin (GetPluginNameStatic(),
                                   GetPluginDescriptionStatic(),
                                   CreateInstance);
}

void
DynamicLoaderMacOSXDYLD::Terminate()
{
    PluginManager::UnregisterPlugin (CreateInstance);
}


lldb_private::ConstString
DynamicLoaderMacOSXDYLD::GetPluginNameStatic()
{
    static ConstString g_name("macosx-dyld");
    return g_name;
}

const char *
DynamicLoaderMacOSXDYLD::GetPluginDescriptionStatic()
{
    return "Dynamic loader plug-in that watches for shared library loads/unloads in MacOSX user processes.";
}


//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
lldb_private::ConstString
DynamicLoaderMacOSXDYLD::GetPluginName()
{
    return GetPluginNameStatic();
}

uint32_t
DynamicLoaderMacOSXDYLD::GetPluginVersion()
{
    return 1;
}

uint32_t
DynamicLoaderMacOSXDYLD::AddrByteSize()
{
    std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());

    switch (m_dyld.header.magic)
    {
        case llvm::MachO::MH_MAGIC:
        case llvm::MachO::MH_CIGAM:
            return 4;
            
        case llvm::MachO::MH_MAGIC_64:
        case llvm::MachO::MH_CIGAM_64:
            return 8;
            
        default:
            break;
    }
    return 0;
}

lldb::ByteOrder
DynamicLoaderMacOSXDYLD::GetByteOrderFromMagic(uint32_t magic)
{
    switch (magic)
    {
        case llvm::MachO::MH_MAGIC:
        case llvm::MachO::MH_MAGIC_64:
            return endian::InlHostByteOrder();
            
        case llvm::MachO::MH_CIGAM:
        case llvm::MachO::MH_CIGAM_64:
            if (endian::InlHostByteOrder() == lldb::eByteOrderBig)
                return lldb::eByteOrderLittle;
            else
                return lldb::eByteOrderBig;
            
        default:
            break;
    }
    return lldb::eByteOrderInvalid;
}