Example support for drgn CLI commands

This implements a "cl" command using the drgn CLI command framework
proposed in osandov/drgn#367. The "cl" command invokes Corelens modules
as sub-commands.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>

drgn_tools/corelens.py

@@ -16,12 +16,14 @@
 import traceback
 from fnmatch import fnmatch
 from pathlib import Path
+from typing import Any
 from typing import Callable
 from typing import Dict
 from typing import List
 from typing import Optional
 from typing import Tuple
 
+import drgn.cli
 from drgn import Program
 
 from drgn_tools.debuginfo import find_debuginfo
@@ -469,7 +471,11 @@ def run(prog: Program, cl_cmd: str) -> None:
     """
     cmd = shlex.split(cl_cmd)
     module_name, args = cmd[0], cmd[1:]
-    module = all_corelens_modules()[module_name]
+    try:
+        module = all_corelens_modules()[module_name]
+    except KeyError:
+        print(f"{module_name}: corelens command not found")
+        return
     try:
         ns = module._parse_args(args, exit_on_error=False)
     except _CorelensArgparseEscapeException:
@@ -497,6 +503,15 @@ def cl(cl_cmd: str) -> None:
     return cl
 
 
+@drgn.cli.command("cl")
+def cl(prog: Program, cmd: str, locals_: Dict[str, Any]) -> None:
+    args = cmd.split(maxsplit=1)
+    if len(args) == 2:
+        run(prog, cmd.split(maxsplit=1)[1])
+    else:
+        _print_module_listing()
+
+
 if __name__ == "__main__":
     # Please, do not ask too many questions about this line. Please. It is a
     # terrible, terrible corner of Python.

setup.py

@@ -104,5 +104,8 @@ def get_version():
             "DRGN=drgn_tools.cli:main",
             "corelens=drgn_tools.corelens:main",
         ],
+        "drgn.command.v1": [
+            "corelens=drgn_tools.corelens",
+        ],
     },
 )