gdbclient.py: Implement --chroot argument.

This allows executables to be debugged inside a chroot (such as the ART
testing chroot).

Change-Id: I1b790c3c2307e240d37ed0afb9a930d00957acec

python-packages/gdbrunner/__init__.py

@@ -142,8 +142,8 @@ def get_pids(device, process_name):
 
 
 def start_gdbserver(device, gdbserver_local_path, gdbserver_remote_path,
-                    target_pid, run_cmd, debug_socket, port, run_as_cmd=None,
-                    lldb=False):
+                    target_pid, run_cmd, debug_socket, port, run_as_cmd=[],
+                    lldb=False, chroot=""):
     """Start gdbserver in the background and forward necessary ports.
 
     Args:
@@ -162,15 +162,15 @@ def start_gdbserver(device, gdbserver_local_path, gdbserver_remote_path,
 
     assert target_pid is None or run_cmd is None
 
+    if chroot:
+        run_as_cmd = ["chroot", chroot] + run_as_cmd
+
     # Remove the old socket file.
-    rm_cmd = ["rm", debug_socket]
-    if run_as_cmd:
-        rm_cmd = run_as_cmd + rm_cmd
-    device.shell_nocheck(rm_cmd)
+    device.shell_nocheck(run_as_cmd + ["rm", debug_socket])
 
     # Push gdbserver to the target.
     if gdbserver_local_path is not None:
-        device.push(gdbserver_local_path, gdbserver_remote_path)
+        device.push(gdbserver_local_path, chroot + gdbserver_remote_path)
 
     # Run gdbserver.
     gdbserver_cmd = [gdbserver_remote_path]
@@ -184,9 +184,8 @@ def start_gdbserver(device, gdbserver_local_path, gdbserver_remote_path,
     else:
         gdbserver_cmd += ["--"] + run_cmd
 
-    forward_gdbserver_port(device, local=port, remote="localfilesystem:{}".format(debug_socket))
+    forward_gdbserver_port(device, local=port, remote="localfilesystem:{}".format(chroot + debug_socket))
 
-    if run_as_cmd:
     gdbserver_cmd = run_as_cmd + gdbserver_cmd
 
     if lldb:

scripts/gdbclient.py

@@ -102,6 +102,9 @@ def parse_args():
     parser.add_argument(
         "--env", nargs=1, action="append", metavar="VAR=VALUE",
         help="set environment variable when running a binary")
+    parser.add_argument(
+        "--chroot", nargs='?', default="", metavar="PATH",
+        help="run command in a chroot in the given directory")
 
     return parser.parse_args()
 
@@ -315,6 +318,9 @@ def do_main():
     sysroot = os.path.join(os.environ["ANDROID_PRODUCT_OUT"], "symbols")
 
     # Make sure the environment matches the attached device.
+    # Skip when running in a chroot because the chroot lunch target may not
+    # match the device's lunch target.
+    if not args.chroot:
         verify_device(root, device)
 
     debug_socket = "/data/local/tmp/debug_socket"
@@ -356,7 +362,7 @@ def do_main():
             gdbrunner.start_gdbserver(
                 device, server_local_path, server_remote_path,
                 target_pid=pid, run_cmd=run_cmd, debug_socket=debug_socket,
-                port=args.port, run_as_cmd=cmd_prefix, lldb=True)
+                port=args.port, run_as_cmd=cmd_prefix, lldb=True, chroot=args.chroot)
         else:
             print(
                 "Connecting to tracing pid {} using local port {}".format(