source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp

//===-- 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/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/State.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/ObjCLanguageRuntime.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"

//#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

using namespace lldb;
using namespace lldb_private;

/// FIXME - The ObjC Runtime trampoline handler doesn't really belong here.
/// I am putting it here so I can invoke it in the Trampoline code here, but
/// it should be moved to the ObjC Runtime support when it is set up.


DynamicLoaderMacOSXDYLD::DYLDImageInfo *
DynamicLoaderMacOSXDYLD::GetImageInfo (Module *module)
{
    const UUID &module_uuid = module->GetUUID();
    DYLDImageInfo::collection::iterator pos, end = m_dyld_image_infos.end();

    // First try just by UUID as it is the safest.
    if (module_uuid.IsValid())
    {
        for (pos = m_dyld_image_infos.begin(); pos != end; ++pos)
        {
            if (pos->uuid == module_uuid)
                return &(*pos);
        }
        
        if (m_dyld.uuid == module_uuid)
            return &m_dyld;
    }

    // Next try by platform path only for things that don't have a valid UUID
    // since if a file has a valid UUID in real life it should also in the
    // dyld info. This is the next safest because the paths in the dyld info
    // are platform paths, not local paths. For local debugging platform == local
    // paths.
    const FileSpec &platform_file_spec = module->GetPlatformFileSpec();
    for (pos = m_dyld_image_infos.begin(); pos != end; ++pos)
    {
        if (pos->file_spec == platform_file_spec && pos->uuid.IsValid() == false)
            return &(*pos);
    }
    
    if (m_dyld.file_spec == platform_file_spec && m_dyld.uuid.IsValid() == false)
        return &m_dyld;

    return NULL;
}

//----------------------------------------------------------------------
// 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)
    {
        const llvm::Triple &triple_ref = process->GetTarget().GetArchitecture().GetTriple();
        if (triple_ref.getOS() == llvm::Triple::Darwin && triple_ref.getVendor() == llvm::Triple::Apple)
            create = true;
    }
    
    if (create)
        return new DynamicLoaderMacOSXDYLD (process);
    return NULL;
}

//----------------------------------------------------------------------
// Constructor
//----------------------------------------------------------------------
DynamicLoaderMacOSXDYLD::DynamicLoaderMacOSXDYLD (Process* process) :
    DynamicLoader(process),
    m_dyld(),
    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_dyld_image_infos(),
    m_dyld_image_infos_stop_id (UINT32_MAX),
    m_mutex(Mutex::eMutexTypeRecursive)
{
}

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
DynamicLoaderMacOSXDYLD::~DynamicLoaderMacOSXDYLD()
{
    Clear(true);
}

//------------------------------------------------------------------
/// Called after attaching a process.
///
/// Allow DynamicLoader plug-ins to execute some code after
/// attaching to a process.
//------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::DidAttach ()
{
    PrivateInitialize(m_process);
    LocateDYLD ();
    SetNotificationBreakpoint ();
}

//------------------------------------------------------------------
/// Called after attaching a process.
///
/// Allow DynamicLoader plug-ins to execute some code after
/// attaching to a process.
//------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::DidLaunch ()
{
    PrivateInitialize(m_process);
    LocateDYLD ();
    SetNotificationBreakpoint ();
}


//----------------------------------------------------------------------
// Clear out the state of this class.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::Clear (bool clear_process)
{
    Mutex::Locker locker(m_mutex);

    if (m_process->IsAlive() && LLDB_BREAK_ID_IS_VALID(m_break_id))
        m_process->ClearBreakpointSiteByID(m_break_id);

    if (clear_process)
        m_process = NULL;
    m_dyld.Clear(false);
    m_dyld_all_image_infos_addr = LLDB_INVALID_ADDRESS;
    m_dyld_all_image_infos.Clear();
    m_break_id = LLDB_INVALID_BREAK_ID;
    m_dyld_image_infos.clear();
}

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

//----------------------------------------------------------------------
// Try and figure out where dyld is by first asking the Process
// if it knows (which currently calls down in the the lldb::Process
// to get the DYLD info (available on SnowLeopard only). If that fails,
// then check in the default addresses.
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::LocateDYLD()
{
    if (m_dyld_all_image_infos_addr == LLDB_INVALID_ADDRESS)
        m_dyld_all_image_infos_addr = m_process->GetImageInfoAddress ();

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

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

    if (executable)
    {
        if (executable->GetArchitecture().GetAddressByteSize() == 8)
        {
            return ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x7fff5fc00000ull);
        }
#if defined (__arm__)
        else
        {
            ArchSpec arm_arch("arm");
            if (arm_arch == executable->Arch())
                return ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x2fe00000);
        }
#endif
        return ReadDYLDInfoFromMemoryAndSetNotificationCallback(0x8fe00000);
    }
    return false;
}

ModuleSP
DynamicLoaderMacOSXDYLD::FindTargetModuleForDYLDImageInfo (const DYLDImageInfo &image_info, bool can_create, bool *did_create_ptr)
{
    if (did_create_ptr)
        *did_create_ptr = false;
    ModuleSP module_sp;
    ModuleList &target_images = m_process->GetTarget().GetImages();
    const bool image_info_uuid_is_valid = image_info.uuid.IsValid();
    if (image_info_uuid_is_valid)
        module_sp = target_images.FindModule(image_info.uuid);
    
    if (!module_sp)
    {
        ArchSpec arch(image_info.GetArchitecture ());

        module_sp = target_images.FindFirstModuleForFileSpec (image_info.file_spec, &arch, NULL);

        if (can_create && !module_sp)
        {
            module_sp = m_process->GetTarget().GetSharedModule (image_info.file_spec,
                                                                arch,
                                                                image_info_uuid_is_valid ? &image_info.uuid : NULL);
            if (did_create_ptr)
                *did_create_ptr = module_sp;
        }
    }
    return module_sp;
}

//----------------------------------------------------------------------
// Assume that dyld is in memory at ADDR and try to parse it's load
// commands
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::ReadDYLDInfoFromMemoryAndSetNotificationCallback(lldb::addr_t addr)
{
    DataExtractor data; // Load command data
    if (ReadMachHeader (addr, &m_dyld.header, &data))
    {
        if (m_dyld.header.filetype == llvm::MachO::HeaderFileTypeDynamicLinkEditor)
        {
            m_dyld.address = addr;
            ModuleSP dyld_module_sp;
            if (ParseLoadCommands (data, m_dyld, &m_dyld.file_spec))
            {
                if (m_dyld.file_spec)
                {
                    dyld_module_sp = FindTargetModuleForDYLDImageInfo (m_dyld, true, NULL);

                    if (dyld_module_sp)
                        UpdateImageLoadAddress (dyld_module_sp.get(), m_dyld);
                }
            }

            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->GetValue().GetLoadAddress(&m_process->GetTarget());
            }

            // Update all image infos
            UpdateAllImageInfos();

            // 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 (m_process->GetTarget().GetImages().AppendIfNeeded (dyld_module_sp))
                UpdateImageLoadAddress(dyld_module_sp.get(), m_dyld);

            return true;
        }
    }
    return false;
}

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

bool
DynamicLoaderMacOSXDYLD::UpdateCommPageLoadAddress(Module *module)
{
    bool changed = false;
    if (module)
    {
        ObjectFile *image_object_file = module->GetObjectFile();
        if (image_object_file)
        {
            SectionList *section_list = image_object_file->GetSectionList ();
            if (section_list)
            {
                uint32_t num_sections = section_list->GetSize();
                for (uint32_t i=0; i<num_sections; ++i)
                {
                    Section* section = section_list->GetSectionAtIndex (i).get();
                    if (section)
                    {
                        const addr_t new_section_load_addr = section->GetFileAddress ();
                        const addr_t old_section_load_addr = m_process->GetTarget().GetSectionLoadList().GetSectionLoadAddress (section);
                        if (old_section_load_addr == LLDB_INVALID_ADDRESS ||
                            old_section_load_addr != new_section_load_addr)
                        {
                            if (m_process->GetTarget().GetSectionLoadList().SetSectionLoadAddress (section, section->GetFileAddress ()))
                                changed = true;
                        }
                    }
                }
            }
        }
    }
    return changed;
}

//----------------------------------------------------------------------
// Update the load addresses for all segments in MODULE using the
// updated INFO that is passed in.
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::UpdateImageLoadAddress (Module *module, DYLDImageInfo& info)
{
    bool changed = false;
    if (module)
    {
        ObjectFile *image_object_file = module->GetObjectFile();
        if (image_object_file)
        {
            SectionList *section_list = image_object_file->GetSectionList ();
            if (section_list)
            {
                // 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)
                info.slide = 0;
                const size_t num_sections = section_list->GetSize();
                size_t sect_idx = 0;
                for (sect_idx = 0; sect_idx < num_sections; ++sect_idx)
                {
                    // Iterate through the object file sections to find the
                    // first section that starts of file offset zero and that
                    // has bytes in the file...
                    Section *section = section_list->GetSectionAtIndex (sect_idx).get();
                    if (section)
                    {
                        // Find the first section that begins at file offset zero
                        // a file size (skip page zero).
                        if (section->GetFileOffset() == 0 && section->GetFileSize() > 0)
                        {
                            // We have now found the section, lets match it up
                            // with the section in the dyld image info structure.
                            const Segment *dyld_segment = info.FindSegment (section->GetName());
                            if (dyld_segment)
                                info.slide = info.address - dyld_segment->addr;
                            // We have found the slide amount, so we can exit
                            // this for loop.
                            break;
                        }
                    }
                }

                // We now know the slide amount, so go through all sections
                // and update the load addresses with the correct values.
                uint32_t num_segments = info.segments.size();
                for (uint32_t i=0; i<num_segments; ++i)
                {
                    SectionSP section_sp(section_list->FindSectionByName(info.segments[i].name));
                    assert (section_sp.get() != NULL);
                    const addr_t new_section_load_addr = info.segments[i].addr + info.slide;
                    const addr_t old_section_load_addr = m_process->GetTarget().GetSectionLoadList().GetSectionLoadAddress (section_sp.get());
                    if (old_section_load_addr == LLDB_INVALID_ADDRESS ||
                        old_section_load_addr != new_section_load_addr)
                    {
                        if (m_process->GetTarget().GetSectionLoadList().SetSectionLoadAddress (section_sp.get(), new_section_load_addr))
                            changed = true;
                    }
                }
            }
        }
    }
    return changed;
}

//----------------------------------------------------------------------
// Update the load addresses for all segments in MODULE using the
// updated INFO that is passed in.
//----------------------------------------------------------------------
bool
DynamicLoaderMacOSXDYLD::UnloadImageLoadAddress (Module *module, DYLDImageInfo& info)
{
    bool changed = false;
    if (module)
    {
        ObjectFile *image_object_file = module->GetObjectFile();
        if (image_object_file)
        {
            SectionList *section_list = image_object_file->GetSectionList ();
            if (section_list)
            {
                uint32_t num_segments = info.segments.size();
                for (uint32_t i=0; i<num_segments; ++i)
                {
                    SectionSP section_sp(section_list->FindSectionByName(info.segments[i].name));
                    assert (section_sp.get() != NULL);
                    const addr_t old_section_load_addr = info.segments[i].addr + info.slide;
                    if (m_process->GetTarget().GetSectionLoadList().SetSectionUnloaded (section_sp.get(), old_section_load_addr))
                        changed = true;
                }
            }
        }
    }
    return changed;
}


//----------------------------------------------------------------------
// 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
    DynamicLoaderMacOSXDYLD* dyld_instance = (DynamicLoaderMacOSXDYLD*) baton;
    dyld_instance->UpdateAllImageInfos();
    // Return true to stop the target, false to just let the target run
    return dyld_instance->GetStopWhenImagesChange();
}

bool
DynamicLoaderMacOSXDYLD::ReadAllImageInfosStructure ()
{
    Mutex::Locker locker(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);
        uint32_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
        assert (sizeof (buf) > count_v11);

        int count;
        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;
        }

        if (m_dyld_all_image_infos.version >= 11)
            count = count_v11;
        else
            count = 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;
}

//----------------------------------------------------------------------
// 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).
//----------------------------------------------------------------------
uint32_t
DynamicLoaderMacOSXDYLD::UpdateAllImageInfos()
{
    LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_DYNAMIC_LOADER));
    ModuleList& target_images = m_process->GetTarget().GetImages();

    if (ReadAllImageInfosStructure ())
    {
        Mutex::Locker locker(m_mutex);
        if (m_process->GetStopID() == m_dyld_image_infos_stop_id)
            m_dyld_image_infos.size();

        uint32_t idx;
        uint32_t i = 0;
        DYLDImageInfo::collection old_dyld_all_image_infos;
        old_dyld_all_image_infos.swap(m_dyld_image_infos);

        // If we made it here, we are assuming that the all dylib info data should
        // be valid, lets read the info array.
        const ByteOrder endian = m_dyld.GetByteOrder();
        const uint32_t addr_size = m_dyld.GetAddressByteSize();

        if (m_dyld_all_image_infos.dylib_info_count > 0)
        {
            if (m_dyld_all_image_infos.dylib_info_addr == 0)
            {
                // DYLD is updating the images right now...
            }
            else
            {
                m_dyld_image_infos.resize(m_dyld_all_image_infos.dylib_info_count);
                const size_t count = m_dyld_image_infos.size() * 3 * addr_size;
                DataBufferHeap info_data(count, 0);
                Error error;
                const size_t bytes_read = m_process->ReadMemory (m_dyld_all_image_infos.dylib_info_addr, 
                                                                 info_data.GetBytes(), 
                                                                 info_data.GetByteSize(),
                                                                 error);
                if (bytes_read == count)
                {
                    uint32_t info_data_offset = 0;
                    DataExtractor info_data_ref(info_data.GetBytes(), info_data.GetByteSize(), endian, addr_size);
                    for (i = 0; info_data_ref.ValidOffset(info_data_offset); i++)
                    {
                        assert (i < m_dyld_image_infos.size());
                        m_dyld_image_infos[i].address = info_data_ref.GetPointer(&info_data_offset);
                        lldb::addr_t path_addr = info_data_ref.GetPointer(&info_data_offset);
                        m_dyld_image_infos[i].mod_date = info_data_ref.GetPointer(&info_data_offset);

                        char raw_path[PATH_MAX];
                        m_process->ReadMemory (path_addr, raw_path, sizeof(raw_path), error);
                        m_dyld_image_infos[i].file_spec.SetFile(raw_path, true);
                    }
                    assert(i == m_dyld_all_image_infos.dylib_info_count);

                    UpdateAllImageInfosHeaderAndLoadCommands();
                }
                else
                {
                    DEBUG_PRINTF( "unable to read all data for all_dylib_infos.");
                    m_dyld_image_infos.clear();
                }
            }
        }
        else
        {
            m_dyld_image_infos.clear();
        }

        // If our new list is smaller than our old list, we have unloaded
        // some shared libraries
        if (m_dyld_image_infos.size() != old_dyld_all_image_infos.size())
        {
            ModuleList unloaded_module_list;
            if (old_dyld_all_image_infos.size() == 0)
            {
                // This is the first time we are loading shared libraries,
                // we need to make sure to trim anything that isn't in the
                // m_dyld_image_infos out of the target module list since
                // we might have shared libraries that got loaded from
                // elsewhere due to DYLD_FRAMEWORK_PATH, or DYLD_LIBRARY_PATH
                // environment variables...
                const size_t num_images = target_images.GetSize();
                for (idx = 0; idx < num_images; ++idx)
                {
                    ModuleSP module_sp (target_images.GetModuleAtIndex (idx));
                    
                    if (GetImageInfo (module_sp.get()) == NULL)
                        unloaded_module_list.AppendIfNeeded (module_sp);
                }
            }
            else
            {
                uint32_t old_idx;
                for (idx = 0; idx < old_dyld_all_image_infos.size(); ++idx)
                {
                    for (old_idx = idx; old_idx < old_dyld_all_image_infos.size(); ++old_idx)
                    {
                        if (m_dyld_image_infos[idx].file_spec == old_dyld_all_image_infos[old_idx].file_spec)
                        {
                            old_dyld_all_image_infos[old_idx].address = LLDB_INVALID_ADDRESS;
                            break;
                        }
                    }
                }

                for (old_idx = 0; old_idx < old_dyld_all_image_infos.size(); ++old_idx)
                {
                    if (old_dyld_all_image_infos[old_idx].address != LLDB_INVALID_ADDRESS)
                    {
                        if (log)
                            old_dyld_all_image_infos[old_idx].PutToLog (log.get());
                        ModuleSP unload_image_module_sp (FindTargetModuleForDYLDImageInfo (old_dyld_all_image_infos[old_idx], false, NULL));
                        if (unload_image_module_sp.get())
                        {
                            if (UnloadImageLoadAddress (unload_image_module_sp.get(), old_dyld_all_image_infos[old_idx]))
                                unloaded_module_list.AppendIfNeeded (unload_image_module_sp);
                        }
                    }
                }
            }

            if (unloaded_module_list.GetSize() > 0)
            {
                if (log)
                {
                    log->PutCString("Unloaded:");
                    unloaded_module_list.LogUUIDAndPaths (log, "DynamicLoaderMacOSXDYLD::ModulesDidUnload");
                }
                m_process->GetTarget().ModulesDidUnload (unloaded_module_list);
            }
        }
        else
        {
            if (log)
                PutToLog(log.get());
        }
        m_dyld_image_infos_stop_id = m_process->GetStopID();
    }
    else
    {
        m_dyld_image_infos.clear();
    }

    const uint32_t num_dylibs = m_dyld_image_infos.size();
    if (num_dylibs > 0)
    {
        ModuleList loaded_module_list;
        for (uint32_t idx = 0; idx<num_dylibs; ++idx)
        {
            ModuleSP image_module_sp (FindTargetModuleForDYLDImageInfo (m_dyld_image_infos[idx], true, NULL));

            if (image_module_sp)
            {
                if (m_dyld_image_infos[idx].header.filetype == llvm::MachO::HeaderFileTypeDynamicLinkEditor)
                    image_module_sp->SetIsDynamicLinkEditor (true);

                ObjectFile *objfile = image_module_sp->GetObjectFile ();
                if (objfile)
                {
                    SectionList *sections = objfile->GetSectionList();
                    if (sections)
                    {
                        ConstString commpage_dbstr("__commpage");
                        Section *commpage_section = sections->FindSectionByName(commpage_dbstr).get();
                        if (commpage_section)
                        {
                            const FileSpec objfile_file_spec = objfile->GetFileSpec();
                            ArchSpec arch (m_dyld_image_infos[idx].GetArchitecture ());
                            ModuleSP commpage_image_module_sp(target_images.FindFirstModuleForFileSpec (objfile_file_spec, &arch, &commpage_dbstr));
                            if (!commpage_image_module_sp)
                            {
                                commpage_image_module_sp = m_process->GetTarget().GetSharedModule (m_dyld_image_infos[idx].file_spec,
                                                                                                   arch,
                                                                                                   &m_dyld_image_infos[idx].uuid,
                                                                                                   &commpage_dbstr,
                                                                                                   objfile->GetOffset() + commpage_section->GetOffset());
                            }
                            if (commpage_image_module_sp)
                                UpdateCommPageLoadAddress (commpage_image_module_sp.get());
                        }
                    }
                }

                // UpdateImageLoadAddress will return true if any segments
                // change load address. We need to check this so we don't
                // mention that all loaded shared libraries are newly loaded
                // each time we hit out dyld breakpoint since dyld will list all
                // shared libraries each time.
                if (UpdateImageLoadAddress (image_module_sp.get(), m_dyld_image_infos[idx]))
                {
                    loaded_module_list.AppendIfNeeded (image_module_sp);
                }
            }
        }
        if (loaded_module_list.GetSize() > 0)
        {
            // FIXME: This should really be in the Runtime handlers class, which should get
            // called by the target's ModulesDidLoad, but we're doing it all locally for now 
            // to save time.
            // Also, I'm assuming there can be only one libobjc dylib loaded...
            
            ObjCLanguageRuntime *objc_runtime = m_process->GetObjCLanguageRuntime();
            if (objc_runtime != NULL && !objc_runtime->HasReadObjCLibrary())
            {
                size_t num_modules = loaded_module_list.GetSize();
                for (int i = 0; i < num_modules; i++)
                {
                    if (objc_runtime->IsModuleObjCLibrary (loaded_module_list.GetModuleAtIndex (i)))
                    {
                        objc_runtime->ReadObjCLibrary (loaded_module_list.GetModuleAtIndex (i));
                        break;
                    }
                }
            }
            if (log)
                loaded_module_list.LogUUIDAndPaths (log, "DynamicLoaderMacOSXDYLD::ModulesDidLoad");
            m_process->GetTarget().ModulesDidLoad (loaded_module_list);
        }
    }
    return m_dyld_image_infos.size();
}

//----------------------------------------------------------------------
// 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))
    {
        uint32_t offset = 0;
        ::memset (header, 0, sizeof(header));

        // Get the magic byte unswapped so we can figure out what we are dealing with
        DataExtractor data(header_bytes.GetBytes(), header_bytes.GetByteSize(), lldb::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::HeaderMagic32:
        case llvm::MachO::HeaderMagic32Swapped:
            data.SetAddressByteSize(4);
            load_cmd_addr += sizeof(llvm::MachO::mach_header);
            break;

        case llvm::MachO::HeaderMagic64:
        case llvm::MachO::HeaderMagic64Swapped:
            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, DYLDImageInfo& dylib_info, FileSpec *lc_id_dylinker)
{
    uint32_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;
            uint32_t load_cmd_offset = offset;
            load_cmd.cmd = data.GetU32 (&offset);
            load_cmd.cmdsize = data.GetU32 (&offset);
            switch (load_cmd.cmd)
            {
            case llvm::MachO::LoadCommandSegment32:
                {
                    segment.name.SetTrimmedCStringWithLength ((const char *)data.GetData(&offset, 16), 16);
                    segment.addr = data.GetU32 (&offset);
                    segment.size = data.GetU32 (&offset);
                    dylib_info.segments.push_back (segment);
                }
                break;

            case llvm::MachO::LoadCommandSegment64:
                {
                    segment.name.SetTrimmedCStringWithLength ((const char *)data.GetData(&offset, 16), 16);
                    segment.addr = data.GetU64 (&offset);
                    segment.size = data.GetU64 (&offset);
                    dylib_info.segments.push_back (segment);
                }
                break;

            case llvm::MachO::LoadCommandDynamicLinkerIdent:
                if (lc_id_dylinker)
                {
                    uint32_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::LoadCommandUUID:
                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;
        }
    }
    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::UpdateAllImageInfosHeaderAndLoadCommands()
{
    uint32_t exe_idx = UINT32_MAX;
    LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_DYNAMIC_LOADER));
    // Read any UUID values that we can get
    for (uint32_t i = 0; i < m_dyld_all_image_infos.dylib_info_count; i++)
    {
        if (!m_dyld_image_infos[i].UUIDValid())
        {
            DataExtractor data; // Load command data
            if (!ReadMachHeader (m_dyld_image_infos[i].address, &m_dyld_image_infos[i].header, &data))
                continue;

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

            if (m_dyld_image_infos[i].header.filetype == llvm::MachO::HeaderFileTypeExecutable)
                exe_idx = i;
            
            if (log)
                m_dyld_image_infos[i].PutToLog (log.get());
        }
    }

    if (exe_idx < m_dyld_image_infos.size())
    {
        ModuleSP exe_module_sp (FindTargetModuleForDYLDImageInfo (m_dyld_image_infos[exe_idx], false, NULL));

        if (!exe_module_sp)
        {
            ArchSpec exe_arch_spec (m_dyld_image_infos[exe_idx].GetArchitecture ());
            exe_module_sp = m_process->GetTarget().GetSharedModule (m_dyld_image_infos[exe_idx].file_spec,
                                                                    exe_arch_spec,
                                                                    &m_dyld_image_infos[exe_idx].uuid);
        }
        
        if (exe_module_sp)
        {
            if (exe_module_sp.get() != m_process->GetTarget().GetExecutableModule().get())
            {
                // Don't load dependent images since we are in dyld where we will know
                // and find out about all images that are loaded
                bool get_dependent_images = false;
                m_process->GetTarget().SetExecutableModule (exe_module_sp, 
                                                            get_dependent_images);
            }
        }
    }
}

//----------------------------------------------------------------------
// Dump a Segment to the file handle provided.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::Segment::PutToLog (Log *log, lldb::addr_t slide) const
{
    if (log)
        log->Printf("\t\t%16s [0x%16.16llx - 0x%16.16llx)", name.AsCString(""), addr + slide, addr + slide + size);
}

const DynamicLoaderMacOSXDYLD::Segment *
DynamicLoaderMacOSXDYLD::DYLDImageInfo::FindSegment (const ConstString &name) const
{
    const size_t num_segments = segments.size();
    for (size_t i=0; i<num_segments; ++i)
    {
        if (segments[i].name == name)
            return &segments[i];
    }
    return NULL;
}


//----------------------------------------------------------------------
// Dump an image info structure to the file handle provided.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::DYLDImageInfo::PutToLog (Log *log) const
{
    if (log == NULL)
        return;
    uint8_t *u = (uint8_t *)uuid.GetBytes();

    if (address == LLDB_INVALID_ADDRESS)
    {
        if (u)
        {
            log->Printf("\t                           modtime=0x%8.8llx uuid=%2.2X%2.2X%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X%2.2X%2.2X%2.2X%2.2X path='%s/%s' (UNLOADED)",
                        mod_date,
                        u[ 0], u[ 1], u[ 2], u[ 3],
                        u[ 4], u[ 5], u[ 6], u[ 7],
                        u[ 8], u[ 9], u[10], u[11],
                        u[12], u[13], u[14], u[15],
                        file_spec.GetDirectory().AsCString(),
                        file_spec.GetFilename().AsCString());
        }
        else
            log->Printf("\t                           modtime=0x%8.8llx path='%s/%s' (UNLOADED)",
                        mod_date,
                        file_spec.GetDirectory().AsCString(),
                        file_spec.GetFilename().AsCString());
    }
    else
    {
        if (u)
        {
            log->Printf("\taddress=0x%16.16llx modtime=0x%8.8llx uuid=%2.2X%2.2X%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X-%2.2X%2.2X%2.2X%2.2X%2.2X%2.2X path='%s/%s'",
                        address,
                        mod_date,
                        u[ 0], u[ 1], u[ 2], u[ 3],
                        u[ 4], u[ 5], u[ 6], u[ 7],
                        u[ 8], u[ 9], u[10], u[11],
                        u[12], u[13], u[14], u[15],
                        file_spec.GetDirectory().AsCString(),
                        file_spec.GetFilename().AsCString());
        }
        else
        {
            log->Printf("\taddress=0x%16.16llx modtime=0x%8.8llx path='%s/%s'",
                        address,
                        mod_date,
                        file_spec.GetDirectory().AsCString(),
                        file_spec.GetFilename().AsCString());

        }
        for (uint32_t i=0; i<segments.size(); ++i)
            segments[i].PutToLog(log, slide);
    }
}

//----------------------------------------------------------------------
// 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;

    Mutex::Locker locker(m_mutex);
    log->Printf("dyld_all_image_infos = { version=%d, count=%d, addr=0x%8.8llx, notify=0x%8.8llx }",
                    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);
    }
}

void
DynamicLoaderMacOSXDYLD::PrivateInitialize(Process *process)
{
    DEBUG_PRINTF("DynamicLoaderMacOSXDYLD::%s() process state = %s\n", __FUNCTION__, StateAsCString(m_process->GetState()));
    Clear(true);
    m_process = process;
    m_process->GetTarget().GetSectionLoadList().Clear();
}

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.

            if (m_process->GetTarget().GetSectionLoadList().ResolveLoadAddress(m_dyld_all_image_infos.notification, so_addr))
            {
                Breakpoint *dyld_break = m_process->GetTarget().CreateBreakpoint (so_addr, true).get();
                dyld_break->SetCallback (DynamicLoaderMacOSXDYLD::NotifyBreakpointHit, this, true);
                m_break_id = dyld_break->GetID();
            }
        }
    }
    return m_break_id != LLDB_INVALID_BREAK_ID;
}

//----------------------------------------------------------------------
// Member function that gets called when the process state changes.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::PrivateProcessStateChanged (Process *process, StateType state)
{
    DEBUG_PRINTF("DynamicLoaderMacOSXDYLD::%s(%s)\n", __FUNCTION__, StateAsCString(state));
    switch (state)
    {
    case eStateConnected:
    case eStateAttaching:
    case eStateLaunching:
    case eStateInvalid:
    case eStateUnloaded:
    case eStateExited:
    case eStateDetached:
        Clear(false);
        break;

    case eStateStopped:
        // Keep trying find dyld and set our notification breakpoint each time
        // we stop until we succeed
        if (!DidSetNotificationBreakpoint () && m_process->IsAlive())
        {
            if (NeedToLocateDYLD ())
                LocateDYLD ();

            SetNotificationBreakpoint ();
        }
        break;

    case eStateRunning:
    case eStateStepping:
    case eStateCrashed:
    case eStateSuspended:
        break;

    default:
        break;
    }
}

ThreadPlanSP
DynamicLoaderMacOSXDYLD::GetStepThroughTrampolinePlan (Thread &thread, bool stop_others)
{
    ThreadPlanSP thread_plan_sp;
    StackFrame *current_frame = thread.GetStackFrameAtIndex(0).get();
    const SymbolContext &current_context = current_frame->GetSymbolContext(eSymbolContextSymbol);
    Symbol *current_symbol = current_context.symbol;
    LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));

    if (current_symbol != NULL)
    {
        if (current_symbol->IsTrampoline())
        {
            const ConstString &trampoline_name = current_symbol->GetMangled().GetName(Mangled::ePreferMangled);
            
            if (trampoline_name)
            {
                SymbolContextList target_symbols;
                ModuleList &images = thread.GetProcess().GetTarget().GetImages();
                images.FindSymbolsWithNameAndType(trampoline_name, eSymbolTypeCode, target_symbols);
                // FIXME - Make the Run to Address take multiple addresses, and
                // run to any of them.
                uint32_t num_symbols = target_symbols.GetSize();
                if (num_symbols == 1)
                {
                    SymbolContext context;
                    AddressRange addr_range;
                    if (target_symbols.GetContextAtIndex(0, context))
                    {
                        context.GetAddressRange (eSymbolContextEverything, addr_range);
                        thread_plan_sp.reset (new ThreadPlanRunToAddress (thread, addr_range.GetBaseAddress(), stop_others));
                    }
                    else
                    {
                        if (log)
                            log->Printf ("Couldn't resolve the symbol context.");
                    }
                }
                else if (num_symbols > 1)
                {
                    std::vector<lldb::addr_t>  addresses;
                    addresses.resize (num_symbols);
                    for (uint32_t i = 0; i < num_symbols; i++)
                    {
                        SymbolContext context;
                        AddressRange addr_range;
                        if (target_symbols.GetContextAtIndex(i, context))
                        {
                            context.GetAddressRange (eSymbolContextEverything, addr_range);
                            lldb::addr_t load_addr = addr_range.GetBaseAddress().GetLoadAddress(&thread.GetProcess().GetTarget());
                            addresses[i] = load_addr;
                        }
                    }
                    if (addresses.size() > 0)
                        thread_plan_sp.reset (new ThreadPlanRunToAddress (thread, addresses, stop_others));
                    else
                    {
                        if (log)
                            log->Printf ("Couldn't resolve the symbol contexts.");
                    }
                }
                else
                {
                    if (log)
                    {
                        log->Printf ("Could not find symbol for trampoline target: \"%s\"", trampoline_name.AsCString());
                    }
                }
            }
        }
    }
    else
    {
        if (log)
            log->Printf ("Could not find symbol for step through.");
    }

    return thread_plan_sp;
}

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);
}


const char *
DynamicLoaderMacOSXDYLD::GetPluginNameStatic()
{
    return "dynamic-loader.macosx-dyld";
}

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


//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
const char *
DynamicLoaderMacOSXDYLD::GetPluginName()
{
    return "DynamicLoaderMacOSXDYLD";
}

const char *
DynamicLoaderMacOSXDYLD::GetShortPluginName()
{
    return GetPluginNameStatic();
}

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