[lldb] Improve breakpoint management for interactive scripted process

This patch improves breakpoint management when doing interactive
scripted process debugging.

In other to know which process set a breakpoint, we need to do some book
keeping on the multiplexer scripted process. When initializing the
multiplexer, we will first copy breakpoints that are already set on the
driving target.

Everytime we launch or resume, we should copy breakpoints from the
multiplexer to the driving process.

When creating a breakpoint from a child process, it needs to be set both
on the multiplexer and on the driving process. We also tag the created
breakpoint with the name and pid of the originator process.

This patch also implements all the requirement to achieve proper
breakpoint management. That involves:

- Adding python interator for breakpoints and watchpoints in SBTarget
- Add a new `ScriptedProcess.create_breakpoint` python method

Differential Revision: https://reviews.llvm.org/D148548

Signed-off-by: Med Ismail Bennani <[email protected]>

Author: medismailben

lldb/bindings/interface/SBTarget.i

@@ -1049,7 +1049,7 @@ public:
 
         def get_modules_access_object(self):
             '''An accessor function that returns a modules_access() object which allows lazy module access from a lldb.SBTarget object.'''
-            return self.modules_access (self)
+            return self.modules_access(self)
 
         def get_modules_array(self):
             '''An accessor function that returns a list() that contains all modules in a lldb.SBTarget object.'''
@@ -1068,18 +1068,81 @@ public:
             object.'''
             return lldb_iter(self, 'GetNumBreakpoints', 'GetBreakpointAtIndex')
 
+        class bkpts_access(object):
+            '''A helper object that will lazily hand out bkpts for a target when supplied an index.'''
+            def __init__(self, sbtarget):
+                self.sbtarget = sbtarget
+
+            def __len__(self):
+                if self.sbtarget:
+                    return int(self.sbtarget.GetNumBreakpoints())
+                return 0
+
+            def __getitem__(self, key):
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
+                        return self.sbtarget.GetBreakpointAtIndex(key)
+                return None
+
+        def get_bkpts_access_object(self):
+            '''An accessor function that returns a bkpts_access() object which allows lazy bkpt access from a lldb.SBtarget object.'''
+            return self.bkpts_access(self)
+
+        def get_target_bkpts(self):
+            '''An accessor function that returns a list() that contains all bkpts in a lldb.SBtarget object.'''
+            bkpts = []
+            for idx in range(self.GetNumBreakpoints()):
+                bkpts.append(self.GetBreakpointAtIndex(idx))
+            return bkpts
+
         def watchpoint_iter(self):
             '''Returns an iterator over all watchpoints in a lldb.SBTarget
             object.'''
             return lldb_iter(self, 'GetNumWatchpoints', 'GetWatchpointAtIndex')
 
+        class watchpoints_access(object):
+            '''A helper object that will lazily hand out watchpoints for a target when supplied an index.'''
+            def __init__(self, sbtarget):
+                self.sbtarget = sbtarget
+
+            def __len__(self):
+                if self.sbtarget:
+                    return int(self.sbtarget.GetNumWatchpoints())
+                return 0
+
+            def __getitem__(self, key):
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
+                        return self.sbtarget.GetWatchpointAtIndex(key)
+                return None
+
+        def get_watchpoints_access_object(self):
+            '''An accessor function that returns a watchpoints_access() object which allows lazy watchpoint access from a lldb.SBtarget object.'''
+            return self.watchpoints_access(self)
+
+        def get_target_watchpoints(self):
+            '''An accessor function that returns a list() that contains all watchpoints in a lldb.SBtarget object.'''
+            watchpoints = []
+            for idx in range(self.GetNumWatchpoints()):
+                bkpts.append(self.GetWatchpointAtIndex(idx))
+            return watchpoints
+
+
         modules = property(get_modules_array, None, doc='''A read only property that returns a list() of lldb.SBModule objects contained in this target. This list is a list all modules that the target currently is tracking (the main executable and all dependent shared libraries).''')
         module = property(get_modules_access_object, None, doc=r'''A read only property that returns an object that implements python operator overloading with the square brackets().\n    target.module[<int>] allows array access to any modules.\n    target.module[<str>] allows access to modules by basename, full path, or uuid string value.\n    target.module[uuid.UUID()] allows module access by UUID.\n    target.module[re] allows module access using a regular expression that matches the module full path.''')
         process = property(GetProcess, None, doc='''A read only property that returns an lldb object that represents the process (lldb.SBProcess) that this target owns.''')
         executable = property(GetExecutable, None, doc='''A read only property that returns an lldb object that represents the main executable module (lldb.SBModule) for this target.''')
         debugger = property(GetDebugger, None, doc='''A read only property that returns an lldb object that represents the debugger (lldb.SBDebugger) that owns this target.''')
         num_breakpoints = property(GetNumBreakpoints, None, doc='''A read only property that returns the number of breakpoints that this target has as an integer.''')
+        breakpoints = property(get_target_bkpts, None, doc='''A read only property that returns a list() of lldb.SBBreakpoint objects for all breakpoints in this target.''')
+        breakpoint = property(get_bkpts_access_object, None, doc='''A read only property that returns an object that can be used to access breakpoints as an array ("bkpt_12 = lldb.target.bkpt[12]").''')
         num_watchpoints = property(GetNumWatchpoints, None, doc='''A read only property that returns the number of watchpoints that this target has as an integer.''')
+        watchpoints = property(get_target_watchpoints, None, doc='''A read only property that returns a list() of lldb.SBwatchpoint objects for all watchpoints in this target.''')
+        watchpoint = property(get_watchpoints_access_object, None, doc='''A read only property that returns an object that can be used to access watchpoints as an array ("watchpoint_12 = lldb.target.watchpoint[12]").''')
         broadcaster = property(GetBroadcaster, None, doc='''A read only property that an lldb object that represents the broadcaster (lldb.SBBroadcaster) for this target.''')
         byte_order = property(GetByteOrder, None, doc='''A read only property that returns an lldb enumeration value (lldb.eByteOrderLittle, lldb.eByteOrderBig, lldb.eByteOrderInvalid) that represents the byte order for this target.''')
         addr_size = property(GetAddressByteSize, None, doc='''A read only property that returns the size in bytes of an address for this target.''')

lldb/bindings/python/python-wrapper.swig

@@ -690,6 +690,18 @@ void *lldb_private::LLDBSWIGPython_CastPyObjectToSBData(PyObject * data) {
   return sb_ptr;
 }
 
+void *lldb_private::LLDBSWIGPython_CastPyObjectToSBBreakpoint(PyObject * data) {
+  lldb::SBBreakpoint *sb_ptr = nullptr;
+
+  int valid_cast =
+      SWIG_ConvertPtr(data, (void **)&sb_ptr, SWIGTYPE_p_lldb__SBBreakpoint, 0);
+
+  if (valid_cast == -1)
+    return NULL;
+
+  return sb_ptr;
+}
+
 void *lldb_private::LLDBSWIGPython_CastPyObjectToSBAttachInfo(PyObject * data) {
   lldb::SBAttachInfo *sb_ptr = nullptr;
 

lldb/examples/python/scripted_process/scripted_process.py

@@ -208,6 +208,23 @@ def get_process_metadata(self):
         """
         return self.metadata
 
+    def create_breakpoint(self, addr, error):
+        """ Create a breakpoint in the scripted process from an address.
+            This is mainly used with interactive scripted process debugging.
+
+        Args:
+            addr (int): Address at which the breakpoint should be set.
+            error (lldb.SBError): Error object.
+
+        Returns:
+            SBBreakpoint: A valid breakpoint object that was created a the specified
+                          address. None if the breakpoint creation failed.
+        """
+        error.SetErrorString("%s doesn't support creating breakpoints."
+                             % self.__class__.__name__)
+        return False
+
+
 class ScriptedThread(metaclass=ABCMeta):
 
     """

lldb/include/lldb/API/SBBreakpoint.h

@@ -13,6 +13,10 @@
 
 class SBBreakpointListImpl;
 
+namespace lldb_private {
+class ScriptInterpreter;
+}
+
 namespace lldb {
 
 class LLDB_API SBBreakpoint {
@@ -151,6 +155,8 @@ class LLDB_API SBBreakpoint {
   friend class SBBreakpointName;
   friend class SBTarget;
 
+  friend class lldb_private::ScriptInterpreter;
+
   lldb::BreakpointSP GetSP() const;
 
   lldb::BreakpointWP m_opaque_wp;

lldb/include/lldb/Interpreter/ScriptInterpreter.h

@@ -10,6 +10,7 @@
 #define LLDB_INTERPRETER_SCRIPTINTERPRETER_H
 
 #include "lldb/API/SBAttachInfo.h"
+#include "lldb/API/SBBreakpoint.h"
 #include "lldb/API/SBData.h"
 #include "lldb/API/SBError.h"
 #include "lldb/API/SBLaunchInfo.h"
@@ -570,6 +571,9 @@ class ScriptInterpreter : public PluginInterface {
 
   Status GetStatusFromSBError(const lldb::SBError &error) const;
 
+  lldb::BreakpointSP
+  GetOpaqueTypeFromSBBreakpoint(const lldb::SBBreakpoint &breakpoint) const;
+
   lldb::ProcessAttachInfoSP
   GetOpaqueTypeFromSBAttachInfo(const lldb::SBAttachInfo &attach_info) const;
 

lldb/include/lldb/Interpreter/ScriptedProcessInterface.h

@@ -45,6 +45,11 @@ class ScriptedProcessInterface : virtual public ScriptedInterface {
 
   virtual StructuredData::DictionarySP GetThreadsInfo() { return {}; }
 
+  virtual bool CreateBreakpoint(lldb::addr_t addr, Status &error) {
+    error.SetErrorString("ScriptedProcess don't support creating breakpoints.");
+    return {};
+  }
+
   virtual lldb::DataExtractorSP
   ReadMemoryAtAddress(lldb::addr_t address, size_t size, Status &error) {
     return {};

lldb/source/Interpreter/ScriptInterpreter.cpp

@@ -76,6 +76,11 @@ ScriptInterpreter::GetDataExtractorFromSBData(const lldb::SBData &data) const {
   return data.m_opaque_sp;
 }
 
+lldb::BreakpointSP ScriptInterpreter::GetOpaqueTypeFromSBBreakpoint(
+    const lldb::SBBreakpoint &breakpoint) const {
+  return breakpoint.m_opaque_wp.lock();
+}
+
 lldb::ProcessAttachInfoSP ScriptInterpreter::GetOpaqueTypeFromSBAttachInfo(
     const lldb::SBAttachInfo &attach_info) const {
   return attach_info.m_opaque_sp;

lldb/source/Plugins/Process/scripted/ScriptedProcess.cpp

@@ -257,7 +257,10 @@ Status ScriptedProcess::EnableBreakpointSite(BreakpointSite *bp_site) {
     return Status("Scripted Processes don't support hardware breakpoints");
   }
 
-  return EnableSoftwareBreakpoint(bp_site);
+  Status error;
+  GetInterface().CreateBreakpoint(bp_site->GetLoadAddress(), error);
+
+  return error;
 }
 
 ArchSpec ScriptedProcess::GetArchitecture() {

lldb/source/Plugins/ScriptInterpreter/Python/SWIGPythonBridge.h

@@ -91,6 +91,7 @@ python::ScopedPythonObject<lldb::SBEvent> ToSWIGWrapper(Event *event);
 } // namespace python
 
 void *LLDBSWIGPython_CastPyObjectToSBData(PyObject *data);
+void *LLDBSWIGPython_CastPyObjectToSBBreakpoint(PyObject *data);
 void *LLDBSWIGPython_CastPyObjectToSBAttachInfo(PyObject *data);
 void *LLDBSWIGPython_CastPyObjectToSBLaunchInfo(PyObject *data);
 void *LLDBSWIGPython_CastPyObjectToSBError(PyObject *data);

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedProcessPythonInterface.cpp

@@ -109,6 +109,22 @@ StructuredData::DictionarySP ScriptedProcessPythonInterface::GetThreadsInfo() {
   return dict;
 }
 
+bool ScriptedProcessPythonInterface::CreateBreakpoint(lldb::addr_t addr,
+                                                      Status &error) {
+  Status py_error;
+  StructuredData::ObjectSP obj =
+      Dispatch("create_breakpoint", py_error, addr, error);
+
+  // If there was an error on the python call, surface it to the user.
+  if (py_error.Fail())
+    error = py_error;
+
+  if (!CheckStructuredDataObject(LLVM_PRETTY_FUNCTION, obj, error))
+    return {};
+
+  return obj->GetBooleanValue();
+}
+
 lldb::DataExtractorSP ScriptedProcessPythonInterface::ReadMemoryAtAddress(
     lldb::addr_t address, size_t size, Status &error) {
   Status py_error;