[lldb/Plugins] Add memory writing capabilities to Scripted Process

This patch adds memory writing capabilities to the Scripted Process plugin.

This allows to user to get a target address and a memory buffer on the
python scripted process implementation that the user can make processing
on before performing the actual write.

This will also be used to write trap instruction to a real process
memory to set a breakpoint.

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

lldb/test/API/functionalities/scripted_process/TestScriptedProcess.py

@@ -150,7 +150,6 @@ class ScriptedProcesTestCase(TestBase):
         self.assertEqual(process_1.GetNumThreads(), 1)
 
         # ... then try reading from target #1 process ...
-        addr = 0x500000000
         message = "Hello, target 1"
         buff = process_1.ReadCStringFromMemory(addr, len(message) + 1, error)
         self.assertSuccess(error)
@@ -158,12 +157,22 @@ class ScriptedProcesTestCase(TestBase):
 
         # ... now, reading again from target #0 process to make sure the call
         # gets dispatched to the right target.
-        addr = 0x500000000
         message = "Hello, target 0"
         buff = process_0.ReadCStringFromMemory(addr, len(message) + 1, error)
         self.assertSuccess(error)
         self.assertEqual(buff, message)
 
+        # Let's write some memory.
+        message = "Hello, world!"
+        bytes_written = process_0.WriteMemoryAsCString(addr, message, error)
+        self.assertSuccess(error)
+        self.assertEqual(bytes_written, len(message) + 1)
+
+        # ... and check if that memory was saved properly.
+        buff = process_0.ReadCStringFromMemory(addr, len(message) + 1, error)
+        self.assertSuccess(error)
+        self.assertEqual(buff, message)
+
         thread = process_0.GetSelectedThread()
         self.assertTrue(thread, "Invalid thread.")
         self.assertEqual(thread.GetThreadID(), 0x19)

lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py

@@ -7,20 +7,29 @@ from lldb.plugins.scripted_process import ScriptedProcess
 from lldb.plugins.scripted_process import ScriptedThread
 
 class DummyScriptedProcess(ScriptedProcess):
+    memory = None
+
     def __init__(self, exe_ctx: lldb.SBExecutionContext, args : lldb.SBStructuredData):
         super().__init__(exe_ctx, args)
         self.threads[0] = DummyScriptedThread(self, None)
-
-    def read_memory_at_address(self, addr: int, size: int, error: lldb.SBError) -> lldb.SBData:
+        self.memory = {}
+        addr = 0x500000000
         debugger = self.target.GetDebugger()
         index = debugger.GetIndexOfTarget(self.target)
+        self.memory[addr] = "Hello, target " + str(index)
+
+    def read_memory_at_address(self, addr: int, size: int, error: lldb.SBError) -> lldb.SBData:
         data = lldb.SBData().CreateDataFromCString(
                                     self.target.GetByteOrder(),
                                     self.target.GetCodeByteSize(),
-                                    "Hello, target " + str(index))
+                                    self.memory[addr])
 
         return data
 
+    def write_memory_at_address(self, addr, data, error):
+        self.memory[addr] = data.GetString(error, 0)
+        return len(self.memory[addr]) + 1
+
     def get_loaded_images(self):
         return self.loaded_images