[lldb/bindings] Add Python ScriptedProcess base class to lldb module

In order to facilitate the writting of Scripted Processes, this patch
introduces a `ScriptedProcess` python base class in the lldb module.

The base class holds the python interface with all the - abstract -
methods that need to be implemented by the inherited class but also some
methods that can be overwritten.

This patch also provides an example of a Scripted Process with the
`MyScriptedProcess` class.

rdar://65508855

Differential Revision: https://reviews.llvm.org/D95712

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

lldb/examples/python/scripted_process/scripted_process.py

@@ -0,0 +1,147 @@
+from abc import ABCMeta, abstractmethod
+import six
+
+import lldb
+
+@six.add_metaclass(ABCMeta)
+class ScriptedProcess:
+
+    """
+    The base class for a scripted process.
+
+    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.
+    """
+
+    @abstractmethod
+    def __init__(self, target, args):
+        """ Construct a scripted process.
+
+        Args:
+            target (lldb.SBTarget): The target launching the scripted process.
+            args (lldb.SBStructuredData): A Dictionary holding arbitrary
+                key/value pairs used by the scripted process.
+        """
+        self.target = None
+        self.args = None
+        if isinstance(target, lldb.SBTarget) and target.IsValid():
+            self.target = target
+        if isinstance(args, lldb.SBStructuredData) and args.IsValid():
+            self.args = args
+
+    @abstractmethod
+    def get_memory_region_containing_address(addr):
+        """ Get the memory region for the scripted process, containing a
+            specific address.
+
+        Args:
+            addr (int): Address to look for in the scripted process memory
+                regions.
+
+        Returns:
+            lldb.SBMemoryRegionInfo: The memory region containing the address.
+                None if out of bounds.
+        """
+        pass
+
+    @abstractmethod
+    def get_thread_with_id(tid):
+        """ Get the scripted process thread with a specific ID.
+
+        Args:
+            tid (int): Thread ID to look for in the scripted process.
+
+        Returns:
+            Dict: The thread represented as a dictionary, withr the
+                tid thread ID. None if tid doesn't match any of the scripted
+                process threads.
+        """
+        pass
+
+    @abstractmethod
+    def get_registers_for_thread(tid):
+        """ Get the register context dictionary for a certain thread of
+            the scripted process.
+
+        Args:
+            tid (int): Thread ID for the thread's register context.
+
+        Returns:
+            Dict: The register context represented as a dictionary, for the
+                tid thread. None if tid doesn't match any of the scripted
+                process threads.
+        """
+        pass
+
+    @abstractmethod
+    def read_memory_at_address(addr, size):
+        """ Get a memory buffer from the scripted process at a certain address,
+            of a certain size.
+
+        Args:
+            addr (int): Address from which we should start reading.
+            size (int): Size of the memory to read.
+
+        Returns:
+            lldb.SBData: An `lldb.SBData` buffer with the target byte size and
+                byte order storing the memory read.
+        """
+        pass
+
+    @abstractmethod
+    def get_loaded_images(self):
+        """ Get the list of loaded images for the scripted process.
+
+        ```
+        class ScriptedProcessImage:
+            def __init__(name, file_spec, uuid, load_address):
+              self.name = name
+              self.file_spec = file_spec
+              self.uuid = uuid
+              self.load_address = load_address
+        ```
+
+        Returns:
+            List[ScriptedProcessImage]: A list of `ScriptedProcessImage`
+                containing for each entry, the name of the library, a UUID,
+                an `lldb.SBFileSpec` and a load address.
+                None if the list is empty.
+        """
+        pass
+
+    def get_process_id(self):
+        """ Get the scripted process identifier.
+
+        Returns:
+            int: The scripted process identifier.
+        """
+        return 0
+
+
+    def launch(self):
+        """ Simulate the scripted process launch.
+
+        Returns:
+            lldb.SBError: An `lldb.SBError` with error code 0.
+        """
+        return lldb.SBError()
+
+    def resume(self):
+        """ Simulate the scripted process resume.
+
+        Returns:
+            lldb.SBError: An `lldb.SBError` with error code 0.
+        """
+        return lldb.SBError()
+
+    @abstractmethod
+    def is_alive(self):
+        """ Check if the scripted process is alive.
+
+        Returns:
+            bool: True if scripted process is alive. False otherwise.
+        """
+        pass