corelens: gracefully handle interrupt and broken pipe

SIGINT and SIGPIPE are handled by Python as exceptions. It's common to
get a SIGINT with a keyboard interrupt, and in these cases the user
typically doesn't want a traceback, they just want to stop corelens. For
broken pipe, this is relatively common for "corelens ... | head -n $num"
commands where a user wants to get just the first few lines. An
exception here would print more than they expect, and would be
unhelpful. Handle both of these so corelens behaves more like other
system utilities.

Signed-off-by: Stephen Brennan <[email protected]>

drgn_tools/corelens.py

@@ -549,6 +549,8 @@ def _run_module(
         if print_header:
             print(f"\n====== MODULE {mod.name} ======")
         mod.run(prog, args)
+    except (KeyboardInterrupt, BrokenPipeError):
+        raise
     except Exception:
         formatted = traceback.format_exc()
         errors.append(
@@ -791,4 +793,9 @@ def cl(cl_cmd: str) -> None:
     # terrible, terrible corner of Python.
     import drgn_tools.corelens
 
-    drgn_tools.corelens.main()
+    try:
+        drgn_tools.corelens.main()
+    except KeyboardInterrupt:
+        sys.exit("interrupted")
+    except BrokenPipeError:
+        pass