[lldb] Add ScriptedPlatform python implementation

This patch introduces both the Scripted Platform python base
implementation and an example for it.

The base implementation is embedded in lldb python module under
`lldb.plugins.scripted_platform`.

This patch also refactor the various SWIG methods to create scripted
objects into a single method, that is now shared between the Scripted
Platform, Process and Thread. It also replaces the target argument by a
execution context object.

Differential Revision: https://reviews.llvm.org/D139250

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/examples/python/scripted_process/crashlog_scripted_process.py

@@ -62,8 +62,8 @@ class CrashLogScriptedProcess(ScriptedProcess):
                                                                self.addr_mask,
                                                                self.target)
 
-    def __init__(self, target: lldb.SBTarget, args : lldb.SBStructuredData):
-        super().__init__(target, args)
+    def __init__(self, exe_ctx: lldb.SBExecutionContext, args : lldb.SBStructuredData):
+        super().__init__(exe_ctx, args)
 
         if not self.target or not self.target.IsValid():
             # Return error

lldb/examples/python/scripted_process/scripted_platform.py

@@ -0,0 +1,96 @@
+from abc import ABCMeta, abstractmethod
+
+import lldb
+
+class ScriptedPlatform(metaclass=ABCMeta):
+
+    """
+    The base class for a scripted platform.
+
+    Most of the base class methods are `@abstractmethod` that need to be
+    overwritten by the inheriting class.
+
+    DISCLAIMER: THIS INTERFACE IS STILL UNDER DEVELOPMENT AND NOT STABLE.
+                THE METHODS EXPOSED MIGHT CHANGE IN THE FUTURE.
+    """
+
+    processes = None
+
+    @abstractmethod
+    def __init__(self, exe_ctx, args):
+        """ Construct a scripted platform.
+
+        Args:
+            exe_ctx (lldb.SBExecutionContext): The execution context for the scripted platform
+            args (lldb.SBStructuredData): A Dictionary holding arbitrary
+                key/value pairs used by the scripted platform.
+        """
+        processes = []
+
+    @abstractmethod
+    def list_processes(self):
+        """ Get a list of processes that are running or that can be attached to on the platform.
+
+        processes = {
+            420: {
+                    name: a.out,
+                    arch: aarch64,
+                    pid: 420,
+                    parent_pid: 42 (optional),
+                    uid: 0 (optional),
+                    gid: 0 (optional),
+            },
+        }
+
+        Returns:
+            Dict: The processes represented as a dictionary, with at least the
+                process ID, name, architecture. Optionally, the user can also
+                provide the parent process ID and the user and group IDs.
+                The dictionary can be empty.
+        """
+        pass
+
+    def get_process_info(self, pid):
+        """ Get the dictionary describing the process.
+
+        Returns:
+            Dict: The dictionary of process info that matched process ID.
+            None if the process doesn't exists
+        """
+        pass
+
+    @abstractmethod
+    def attach_to_process(self, attach_info):
+        """ Attach to a process.
+
+        Args:
+            attach_info (lldb.SBAttachInfo): The information related to attach to a process.
+
+        Returns:
+            lldb.SBError: A status object notifying if the attach succeeded.
+        """
+        pass
+
+    @abstractmethod
+    def launch_process(self, launch_info):
+        """ Launch a process.
+
+        Args:
+            launch_info (lldb.SBLaunchInfo): The information related to the process launch.
+
+        Returns:
+            lldb.SBError: A status object notifying if the launch succeeded.
+        """
+        pass
+
+    @abstractmethod
+    def kill_process(self, pid):
+        """ Kill a process.
+
+        Args:
+            pid (int): Process ID for the process to be killed.
+
+        Returns:
+            lldb.SBError: A status object notifying if the shutdown succeeded.
+        """
+        pass

lldb/examples/python/scripted_process/scripted_process.py

@@ -20,17 +20,20 @@ class ScriptedProcess(metaclass=ABCMeta):
     metadata = None
 
     @abstractmethod
-    def __init__(self, target, args):
+    def __init__(self, exe_ctx, args):
         """ Construct a scripted process.
 
         Args:
-            target (lldb.SBTarget): The target launching the scripted process.
+            exe_ctx (lldb.SBExecutionContext): The execution context for the scripted process.
             args (lldb.SBStructuredData): A Dictionary holding arbitrary
                 key/value pairs used by the scripted process.
         """
+        target = None
         self.target = None
         self.args = None
         self.arch = None
+        if isinstance(exe_ctx, lldb.SBExecutionContext):
+            target = exe_ctx.target
         if isinstance(target, lldb.SBTarget) and target.IsValid():
             self.target = target
             triple = self.target.triple