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/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 "DynamicLoaderMacOSXDYLDLog.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.

//----------------------------------------------------------------------
// 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)
{
    return new DynamicLoaderMacOSXDYLD (process);
}

//----------------------------------------------------------------------
// Constructor
//----------------------------------------------------------------------
DynamicLoaderMacOSXDYLD::DynamicLoaderMacOSXDYLD (Process* process) :
    DynamicLoader(process),
    m_dyld(),
    m_dyld_all_image_infos_addr(LLDB_INVALID_ADDRESS),
    m_dyld_all_image_infos(),
    m_break_id(LLDB_INVALID_BREAK_ID),
    m_dyld_image_infos(),
    m_mutex(Mutex::eMutexTypeRecursive),
    m_objc_trampoline_handler_ap(NULL)
{
}

//----------------------------------------------------------------------
// 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);
    if (NeedToLocateDYLD ())
        LocateDYLD ();
    SetNotificationBreakpoint ();
    UpdateAllImageInfos();
}

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


//----------------------------------------------------------------------
// 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;
}

//----------------------------------------------------------------------
// 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 == MH_DYLINKER)
        {
            m_dyld.address = addr;
            ModuleSP dyld_module_sp;
            if (ParseLoadCommands (data, m_dyld, &m_dyld.file_spec))
            {
                if (m_dyld.file_spec)
                {
                    ArchSpec dyld_arch(eArchTypeMachO, m_dyld.header.cputype, m_dyld.header.cpusubtype);
                    dyld_module_sp = m_process->GetTarget().GetImages().FindFirstModuleForFileSpec (m_dyld.file_spec);

                    if (dyld_module_sp.get() == NULL || dyld_module_sp->GetArchitecture() != dyld_arch)
                    {
                        dyld_module_sp = m_process->GetTarget().GetSharedModule (m_dyld.file_spec,
                                                                                 dyld_arch,
                                                                                 &m_dyld.uuid);
                    }

                    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);
            }

            // 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().AppendInNeeded (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->GetSectionLoadAddress (section);
                        if (old_section_load_addr == LLDB_INVALID_ADDRESS ||
                            old_section_load_addr != new_section_load_addr)
                        {
                            if (m_process->SectionLoaded (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, struct 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->GetSectionLoadAddress (section_sp.get());
                    if (old_section_load_addr == LLDB_INVALID_ADDRESS ||
                        old_section_load_addr != new_section_load_addr)
                    {
                        if (m_process->SectionLoaded (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, struct 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->SectionUnloaded (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);
    m_dyld_all_image_infos.Clear();
    if (m_dyld_all_image_infos_addr != LLDB_INVALID_ADDRESS)
    {
        const ByteOrder endian = m_process->GetByteOrder();
        const uint32_t addr_size = m_process->GetAddressByteSize();
        uint8_t buf[256];
        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)
        {
            DataExtractor data(buf, 4, endian, addr_size);
            uint32_t 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)
        {
            DataExtractor data(buf, count, endian, addr_size);
            uint32_t 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;
                }
            }
            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()
{
    if (ReadAllImageInfosStructure ())
    {
        Mutex::Locker locker(m_mutex);
        uint32_t idx;
        Error error;
        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_process->GetByteOrder();
        const uint32_t addr_size = m_process->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);
                    }
                    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;
            for (idx = m_dyld_image_infos.size(); idx < old_dyld_all_image_infos.size(); ++idx)
            {
                ModuleSP unload_image_module_sp(m_process->GetTarget().GetImages().FindFirstModuleForFileSpec (old_dyld_all_image_infos[idx].file_spec));
                if (unload_image_module_sp.get())
                {
                    if (UnloadImageLoadAddress (unload_image_module_sp.get(), old_dyld_all_image_infos[idx]))
                        unloaded_module_list.AppendInNeeded (unload_image_module_sp);
                }
            }
            if (unloaded_module_list.GetSize() > 0)
                m_process->GetTarget().ModulesDidUnload (unloaded_module_list);
        }
    }
    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)
        {
            ArchSpec arch_spec(eArchTypeMachO, m_dyld_image_infos[idx].header.cputype, m_dyld_image_infos[idx].header.cpusubtype);
            ModuleSP image_module_sp(m_process->GetTarget().GetImages().FindFirstModuleForFileSpec (m_dyld_image_infos[idx].file_spec));
            if (image_module_sp.get() == NULL || image_module_sp->GetArchitecture() != arch_spec)
            {
                image_module_sp = m_process->GetTarget().GetSharedModule (m_dyld_image_infos[idx].file_spec,
                                                                          arch_spec,
                                                                          &m_dyld_image_infos[idx].uuid);
            }

            if (image_module_sp)
            {
                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)
                        {
                            FileSpec objfile_file_spec(objfile->GetFileSpec());
                            ModuleSP commpage_image_module_sp(m_process->GetTarget().GetImages().FindFirstModuleForFileSpec (objfile_file_spec, &commpage_dbstr));
                            if (commpage_image_module_sp.get() == NULL)
                            {
                                commpage_image_module_sp = m_process->GetTarget().GetSharedModule (m_dyld_image_infos[idx].file_spec,
                                                                                                   arch_spec,
                                                                                                   &m_dyld_image_infos[idx].uuid,
                                                                                                   &commpage_dbstr,
                                                                                                   objfile->GetOffset() + commpage_section->GetOffset());
                                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.AppendInNeeded (image_module_sp);
                }
            }
        }
        PutToLog(DynamicLoaderMacOSXDYLDLog::GetLogIfAllCategoriesSet (1));
        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...

            if (m_objc_trampoline_handler_ap.get() == NULL)
            {
                size_t num_modules = loaded_module_list.GetSize();
                for (int i = 0; i < num_modules; i++)
                {
                    if (ObjCTrampolineHandler::ModuleIsObjCLibrary (loaded_module_list.GetModuleAtIndex (i)))
                    {
                        m_objc_trampoline_handler_ap.reset (new ObjCTrampolineHandler(m_process->GetSP(), loaded_module_list.GetModuleAtIndex (i)));
                        break;
                    }
                }
            }
            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, struct mach_header *header, DataExtractor *load_command_data)
{
    DataBufferHeap header_bytes(sizeof(struct mach_header), 0);
    Error error;
    size_t bytes_read = m_process->ReadMemory (addr,
                                               header_bytes.GetBytes(),
                                               header_bytes.GetByteSize(),
                                               error);
    if (bytes_read == sizeof(struct 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(), eByteOrderHost, 4);
        header->magic = data.GetU32(&offset);
        lldb::addr_t load_cmd_addr = addr;
        data.SetByteOrder(DynamicLoaderMacOSXDYLD::GetByteOrderFromMagic(header->magic));
        switch (header->magic)
        {
        case MH_MAGIC:
        case MH_CIGAM:
            data.SetAddressByteSize(4);
            load_cmd_addr += sizeof(struct mach_header);
            break;

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

        default:
            return false;
        }

        // Read the rest of dyld's mach header
        if (data.GetU32(&offset, &header->cputype, (sizeof(struct 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, struct 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(struct load_command)))
        {
            struct 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 LC_SEGMENT:
                {
                    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 LC_SEGMENT_64:
                {
                    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 LC_ID_DYLINKER:
                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);
                }
                break;

            case 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;
        }
    }
    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;
    // 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 == MH_EXECUTE)
                exe_idx = i;
        }
    }

    if (exe_idx < m_dyld_image_infos.size())
    {
        bool set_executable = false;
        ArchSpec dyld_exe_arch_spec(eArchTypeMachO, m_dyld_image_infos[exe_idx].header.cputype, m_dyld_image_infos[exe_idx].header.cpusubtype);
        ModuleSP exe_module_sp(m_process->GetTarget().GetExecutableModule());
        if (exe_module_sp.get())
        {
            if (exe_module_sp->GetFileSpec() != m_dyld_image_infos[exe_idx].file_spec ||
                exe_module_sp->GetArchitecture() != dyld_exe_arch_spec)
                set_executable = true;
        }
        else
            set_executable = true;

        if (set_executable)
        {
            exe_module_sp = m_process->GetTarget().GetSharedModule (m_dyld_image_infos[exe_idx].file_spec,
                                                                    dyld_exe_arch_spec,
                                                                    &m_dyld_image_infos[exe_idx].uuid);
            if (exe_module_sp.get())
            {
                // If we found the file where it purported to be, then it should
                // be safe to load dependent images.
                bool get_dependent_images = exe_module_sp->GetFileSpec() == m_dyld_image_infos[exe_idx].file_spec;

                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->Printf("\tdyld_image_infos");
        for (i = 0; i<count; i++)
            m_dyld_image_infos[i].PutToLog(log);
    }
}

//----------------------------------------------------------------------
// Static callback function that gets called when the process state
// changes.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::Initialize(void *baton, Process *process)
{
    ((DynamicLoaderMacOSXDYLD*)baton)->PrivateInitialize(process);
}

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


//----------------------------------------------------------------------
// Static callback function that gets called when the process state
// changes.
//----------------------------------------------------------------------
void
DynamicLoaderMacOSXDYLD::ProcessStateChanged(void *baton, Process *process, StateType state)
{
    ((DynamicLoaderMacOSXDYLD*)baton)->PrivateProcessStateChanged(process, state);
}

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->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;
}

//----------------------------------------------------------------------Target.h

// 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 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;

    if (current_symbol != NULL)
    {
        if (current_symbol->IsTrampoline())
        {
            const ConstString &trampoline_name = current_symbol->GetMangled().GetName();
            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.
                if (target_symbols.GetSize() == 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 (target_symbols.GetSize() > 1)
                {
                    Log *log = DynamicLoaderMacOSXDYLDLog::GetLogIfAllCategoriesSet (1);
                    if (log)
                    {
                        log->Printf ("Found more than one symbol for trampoline target: \"%s\"", trampoline_name.AsCString());
                    }
                }
                else
                {
                    Log *log = DynamicLoaderMacOSXDYLDLog::GetLogIfAllCategoriesSet (1);
                    if (log)
                    {
                        log->Printf ("Could not find symbol for trampoline target: \"%s\"", trampoline_name.AsCString());
                    }
                }
            }
        }
    }

    if (thread_plan_sp == NULL && m_objc_trampoline_handler_ap.get())
        thread_plan_sp = m_objc_trampoline_handler_ap->GetStepThroughDispatchPlan (thread, stop_others);

    return thread_plan_sp;
}

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;
}

void
DynamicLoaderMacOSXDYLD::GetPluginCommandHelp (const char *command, Stream *strm)
{
}

Error
DynamicLoaderMacOSXDYLD::ExecutePluginCommand (Args &command, Stream *strm)
{
    Error error;
    error.SetErrorString("No plug-in command are currently supported.");
    return error;
}

Log *
DynamicLoaderMacOSXDYLD::EnablePluginLogging (Stream *strm, Args &command)
{
    return NULL;
}