<rdar://problem/13590152>

Providing a dummy RegisterContext to secure against faulty Python OS plugins that do not return a valid RegisterContext
The RegisterContextDummy exports a PC with a constant 0xFFFFFFFFFFFFFFFF value

llvm-svn: 180033

3 files changed, 222 insertions, 0 deletions

diff --git a/lldb/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp b/lldb/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp
index 6e2aadb7fde..a7aaedb9a0c 100644
--- a/lldb/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp
+++ b/lldb/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp
@@ -33,6 +33,7 @@
 #include "lldb/Target/ThreadList.h"
 #include "lldb/Target/Thread.h"
 #include "Plugins/Process/Utility/DynamicRegisterInfo.h"
+#include "Plugins/Process/Utility/RegisterContextDummy.h"
 #include "Plugins/Process/Utility/RegisterContextMemory.h"
 #include "Plugins/Process/Utility/ThreadMemory.h"
 
@@ -333,6 +334,13 @@ OperatingSystemPython::CreateRegisterContextForThread (Thread *thread, addr_t re
             }
         }
     }
+    // if we still have no register data, fallback on a dummy context to avoid crashing
+    if (!reg_ctx_sp)
+    {
+        if (log)
+            log->Printf ("OperatingSystemPython::CreateRegisterContextForThread (tid = 0x%" PRIx64 ") forcing a dummy register context", thread->GetID());
+        reg_ctx_sp.reset(new RegisterContextDummy(*thread,0,target.GetArchitecture().GetAddressByteSize()));
+    }
     return reg_ctx_sp;
 }
 
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextDummy.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextDummy.cpp
new file mode 100644
index 00000000000..1e282ce74f2
--- /dev/null
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextDummy.cpp
@@ -0,0 +1,137 @@
+//===-- RegisterContextDummy.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/lldb-private.h"
+#include "lldb/Core/Address.h"
+#include "lldb/Core/AddressRange.h"
+#include "lldb/Core/DataBufferHeap.h"
+#include "lldb/Core/Log.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/RegisterValue.h"
+#include "lldb/Core/Value.h"
+#include "lldb/Expression/DWARFExpression.h"
+#include "lldb/Symbol/FuncUnwinders.h"
+#include "lldb/Symbol/Function.h"
+#include "lldb/Symbol/ObjectFile.h"
+#include "lldb/Symbol/SymbolContext.h"
+#include "lldb/Symbol/Symbol.h"
+#include "lldb/Target/ABI.h"
+#include "lldb/Target/ExecutionContext.h"
+#include "lldb/Target/Process.h"
+#include "lldb/Target/StackFrame.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/DynamicLoader.h"
+
+#include "RegisterContextDummy.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+RegisterContextDummy::RegisterContextDummy (Thread &thread, uint32_t concrete_frame_idx, uint32_t address_byte_size) :
+RegisterContext (thread, concrete_frame_idx)
+{
+    m_reg_set0.name = "General Purpose Registers";
+    m_reg_set0.short_name = "GPR";
+    m_reg_set0.num_registers = 1;
+    m_reg_set0.registers = new uint32_t(0);
+    
+    m_pc_reg_info.name = "pc";
+    m_pc_reg_info.alt_name = "pc";
+    m_pc_reg_info.byte_offset = 0;
+    m_pc_reg_info.byte_size = address_byte_size;
+    m_pc_reg_info.encoding = eEncodingUint;
+    m_pc_reg_info.format = eFormatPointer;
+    m_pc_reg_info.invalidate_regs = NULL;
+    m_pc_reg_info.value_regs = NULL;
+    m_pc_reg_info.kinds[eRegisterKindGCC] = LLDB_INVALID_REGNUM;
+    m_pc_reg_info.kinds[eRegisterKindDWARF] = LLDB_INVALID_REGNUM;
+    m_pc_reg_info.kinds[eRegisterKindGeneric] = LLDB_REGNUM_GENERIC_PC;
+    m_pc_reg_info.kinds[eRegisterKindGDB] = LLDB_INVALID_REGNUM;
+    m_pc_reg_info.kinds[eRegisterKindLLDB] = LLDB_INVALID_REGNUM;
+}
+
+RegisterContextDummy::~RegisterContextDummy ()
+{
+    delete m_reg_set0.registers;
+    delete m_pc_reg_info.invalidate_regs;
+    delete m_pc_reg_info.value_regs;
+}
+
+void
+RegisterContextDummy::InvalidateAllRegisters () {}
+
+size_t
+RegisterContextDummy::GetRegisterCount ()
+{
+    return 1;
+}
+
+const lldb_private::RegisterInfo *
+RegisterContextDummy::GetRegisterInfoAtIndex (size_t reg)
+{
+    if (reg)
+        return NULL;
+    return &m_pc_reg_info;
+}
+
+size_t
+RegisterContextDummy::GetRegisterSetCount ()
+{
+    return 1;
+}
+
+const lldb_private::RegisterSet *
+RegisterContextDummy::GetRegisterSet (size_t reg_set)
+{
+    if (reg_set)
+        return NULL;
+    return &m_reg_set0;
+}
+
+bool
+RegisterContextDummy::ReadRegister (const lldb_private::RegisterInfo *reg_info, lldb_private::RegisterValue &value)
+{
+    if (!reg_info)
+        return false;
+    uint32_t reg_number = reg_info->kinds[eRegisterKindGeneric];
+    if (reg_number == LLDB_REGNUM_GENERIC_PC)
+    {
+        value.SetUInt(LLDB_INVALID_ADDRESS, reg_info->byte_size);
+        return true;
+    }
+    return false;
+}
+
+bool
+RegisterContextDummy::WriteRegister (const lldb_private::RegisterInfo *reg_info, const lldb_private::RegisterValue &value)
+{
+    return false;
+}
+
+bool
+RegisterContextDummy::ReadAllRegisterValues (lldb::DataBufferSP &data_sp)
+{
+    return false;
+}
+
+bool
+RegisterContextDummy::WriteAllRegisterValues (const lldb::DataBufferSP &data_sp)
+{
+    return false;
+}
+
+uint32_t
+RegisterContextDummy::ConvertRegisterKindToRegisterNumber (uint32_t kind, uint32_t num)
+{
+    if (kind == eRegisterKindGeneric && num == LLDB_REGNUM_GENERIC_PC)
+        return 0;
+    return LLDB_INVALID_REGNUM;
+}
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextDummy.h b/lldb/source/Plugins/Process/Utility/RegisterContextDummy.h
new file mode 100644
index 00000000000..ee8d5a134bb
--- /dev/null
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextDummy.h
@@ -0,0 +1,77 @@
+//===-- RegisterContextDummy.h ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef lldb_RegisterContextDummy_h_
+#define lldb_RegisterContextDummy_h_
+
+#include <vector>
+
+#include "lldb/lldb-private.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Symbol/SymbolContext.h"
+
+namespace lldb_private {
+    
+class RegisterContextDummy : public lldb_private::RegisterContext
+{
+public:
+    typedef std::shared_ptr<RegisterContextDummy> SharedPtr;
+    
+    RegisterContextDummy (Thread &thread, uint32_t concrete_frame_idx, uint32_t address_byte_size);
+    
+    ///
+    // pure virtual functions from the base class that we must implement
+    ///
+
+    virtual
+    ~RegisterContextDummy ();
+
+    virtual void
+    InvalidateAllRegisters ();
+
+    virtual size_t
+    GetRegisterCount ();
+
+    virtual const lldb_private::RegisterInfo *
+    GetRegisterInfoAtIndex (size_t reg);
+
+    virtual size_t
+    GetRegisterSetCount ();
+
+    virtual const lldb_private::RegisterSet *
+    GetRegisterSet (size_t reg_set);
+
+    virtual bool
+    ReadRegister (const lldb_private::RegisterInfo *reg_info, lldb_private::RegisterValue &value);
+
+    virtual bool
+    WriteRegister (const lldb_private::RegisterInfo *reg_info, const lldb_private::RegisterValue &value);
+
+    virtual bool
+    ReadAllRegisterValues (lldb::DataBufferSP &data_sp);
+
+    virtual bool
+    WriteAllRegisterValues (const lldb::DataBufferSP &data_sp);
+
+    virtual uint32_t
+    ConvertRegisterKindToRegisterNumber (uint32_t kind, uint32_t num);
+    
+private:
+    //------------------------------------------------------------------
+    // For RegisterContextLLDB only
+    //------------------------------------------------------------------
+    
+    lldb_private::RegisterSet m_reg_set0; // register set 0 (PC only)
+    lldb_private::RegisterInfo m_pc_reg_info;
+    
+    DISALLOW_COPY_AND_ASSIGN (RegisterContextDummy);
+};
+} // namespace lldb_private
+
+#endif  // lldb_RegisterContextDummy_h_