Run `run -s` automatically for `entry` (#3069)

* Run `run -s` automatically for `entry`

* Change comment in entry command

pwndbg/commands/start.py

@@ -134,11 +134,18 @@ def entry(args=None) -> None:
         args = []
 
     if pwndbg.dbg.is_gdblib_available():
+        # If this is GDB, just start the process ourselves.
         run = "starti " + " ".join(map(quote, args))
         gdb.execute(run, from_tty=False)
     else:
-        # TODO: LLDB, In the future, we should handle `run -s` here to automate setup.
-        # For now, we only support stopping at the entry breakpoint.
+        # For now, there is no debugger-agnostic way to start a process from
+        # inside a command, so the best we can do is expect that the back-end
+        # picks up that this command is being called, and starts the process on
+        # our behalf, and error out if it does not.
+        #
+        # `pwndbg-lldb` implements starting as a partial command override in the CLI.
+        #
+        # TODO: In the future, we should handle starts using an in-command mechanism.
         if not pwndbg.aglib.proc.alive:
             print(
                 M.error(

pwndbg/dbg/lldb/repl/__init__.py

@@ -569,6 +569,26 @@ def exec_repl_command(
         run_ipython_shell()
         return True
 
+    if (
+        bits[0] == pwndbg.commands.start.entry.command_name
+        or bits[0] in pwndbg.commands.start.entry.aliases
+    ):
+        # 'entry' is actually a Pwndbg command. For convenience, we launch the
+        # process on its behalf, before letting it run.
+        #
+        # In the LLDB back-end, there is no proper mechanism to make a process
+        # start from inside of a command, as there is in GDB. Ideally, we'd
+        # rework `ProcessDriver` so that it lets us do that with an execution
+        # controller, but that is quite a bit of work to fix a single command,
+        # when using an override is enough to achieve the same goal.
+        #
+        # In any case, we should consider doing it if this proves to be too janky.
+        if not driver.has_process():
+            process_launch(driver, relay, ["-s"], dbg)
+
+        # This intentionally falls through. We want LLDB to do the rest of the
+        # work of processing 'entry'.
+
     # The command hasn't matched any of our filtered commands, just let LLDB
     # handle it normally. Either in the context of the process, if we have
     # one, or just in a general context.