gdb: implement missing debug handler hook for Python

This commit builds on the previous commit, and implements the
extension_language_ops::handle_missing_debuginfo function for Python.
This hook will give user supplied Python code a chance to help find
missing debug information.

The implementation of the new hook is pretty minimal within GDB's C++
code; most of the work is out-sourced to a Python implementation which
is modelled heavily on how GDB's Python frame unwinders are
implemented.

The following new commands are added as commands implemented in
Python, this is similar to how the Python unwinder commands are
implemented:

  info missing-debug-handlers
  enable missing-debug-handler LOCUS HANDLER
  disable missing-debug-handler LOCUS HANDLER

To make use of this extension hook a user will create missing debug
information handler objects, and registers these handlers with GDB.
When GDB encounters an objfile that is missing debug information, each
handler is called in turn until one is able to help.  Here is a
minimal handler that does nothing useful:

  import gdb
  import gdb.missing_debug

  class MyFirstHandler(gdb.missing_debug.MissingDebugHandler):
      def __init__(self):
          super().__init__("my_first_handler")

      def __call__(self, objfile):
          # This handler does nothing useful.
          return None

  gdb.missing_debug.register_handler(None, MyFirstHandler())

Returning None from the __call__ method tells GDB that this handler
was unable to find the missing debug information, and GDB should ask
any other registered handlers.

By extending the __call__ method it is possible for the Python
extension to locate the debug information for objfile and return a
value that tells GDB how to use the information that has been located.

Possible return values from a handler:

  - None: This means the handler couldn't help.  GDB will call other
          registered handlers to see if they can help instead.

  - False: The handler has done all it can, but the debug information
           for the objfile still couldn't be found.  GDB will not call
	   any other handlers, and will continue without the debug
	   information for objfile.

  - True: The handler has installed the debug information into a
          location where GDB would normally expect to find it.  GDB
	  should look again for the debug information.

  - A string: The handler can return a filename, which is the file
              containing the missing debug information.  GDB will load
	      this file.

When a handler returns True, GDB will look again for the debug
information, but only using the standard built-in build-id and
.gnu_debuglink based lookup strategies.  It is not possible for an
extension to trigger another debuginfod lookup; the assumption is that
the debuginfod server is remote, and out of the control of extensions
running within GDB.

Handlers can be registered globally, or per program space.  GDB checks
the handlers for the current program space first, and then all of the
global handles.  The first handler that returns a value that is not
None, has "handled" the objfile, at which point GDB continues.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>

3 files changed, 615 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.python/py-missing-debug.c b/gdb/testsuite/gdb.python/py-missing-debug.c
new file mode 100644
index 0000000..8cbea3b
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-missing-debug.c
@@ -0,0 +1,22 @@
+/* This test program is part of GDB, the GNU debugger.
+
+   Copyright 2023 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+int
+main ()
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.python/py-missing-debug.exp b/gdb/testsuite/gdb.python/py-missing-debug.exp
new file mode 100644
index 0000000..3e0d70b
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-missing-debug.exp
@@ -0,0 +1,473 @@
+# Copyright (C) 2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib gdb-python.exp
+
+require allow_python_tests
+
+standard_testfile
+
+if {[build_executable "failed to prepare" ${testfile} ${srcfile}]} {
+    return -1
+}
+
+# Remove debug information from BINFILE and place it into
+# BINFILE.debug.
+if {[gdb_gnu_strip_debug $binfile]} {
+    unsupported "cannot produce separate debug info files"
+    return -1
+}
+
+set remote_python_file \
+    [gdb_remote_download host ${srcdir}/${subdir}/${testfile}.py]
+
+set debug_filename ${binfile}.debug
+set hidden_filename ${binfile}.hidden
+
+# Start GDB.
+clean_restart
+
+# Some initial sanity checks; initially, we can find the debug information
+# (this will use the .gnu_debuglink), then after we move the debug
+# information, reload the executable, now the debug can't be found.
+with_test_prefix "initial checks" {
+    # Load BINFILE, we should find the separate debug information.
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "debug"} \
+	"debug info is found"
+
+    # Rename the debug information file, re-load BINFILE, GDB should fail
+    # to find the debug information
+    remote_exec build "mv $debug_filename $hidden_filename"
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "nodebug"} \
+	"debug info no longer found"
+}
+
+# Load the Python script into GDB.
+gdb_test "source $remote_python_file" "^Success" \
+    "source python script"
+
+# Setup the separate debug info directory.  This isn't actually needed until
+# some of the later tests, but might as well get this done now.
+set debug_directory [standard_output_file "debug-dir"]
+remote_exec build "mkdir -p $debug_directory"
+gdb_test_no_output "set debug-file-directory $debug_directory" \
+    "set debug-file-directory"
+
+# Initially the missing debug handler we install is in a mode where it
+# returns None, indicating that it can't help locate the debug information.
+# Check this works as expected.
+with_test_prefix "handler returning None" {
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(None, handler_obj)" \
+	"register the initial handler"
+
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "nodebug"} \
+	"debug info not found"
+
+    # Check the handler was only called once.
+    gdb_test "python print(handler_obj.call_count)" "^1" \
+	"check handler was only called once"
+}
+
+# Now configure the handler to move the debug file back to the
+# .gnu_debuglink location and then return True, this will cause GDB to
+# recheck, at which point it should find the debug info.
+with_test_prefix "handler in gnu_debuglink mode" {
+    gdb_test_no_output "python handler_obj.set_mode(Mode.RETURN_TRUE, \
+						    \"$hidden_filename\", \
+						    \"$debug_filename\")" \
+	"confirgure handler"
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "debug"} "debug info found"
+
+    # Check the handler was only called once.
+    gdb_test "python print(handler_obj.call_count)" "^1" \
+	"check handler was only called once"
+}
+
+# Setup a directory structure based on the build-id of BINFILE, but don't
+# move the debug information into place just yet.
+#
+# Instead, configure the handler to move the debug info into the build-id
+# directory.
+#
+# Reload BINFILE, at which point the handler will move the debug info into
+# the build-id directory and return True, GDB will then recheck for the
+# debug information, and should find it.
+with_test_prefix "handler in build-id mode" {
+    # Move the debug file out of the way once more.
+    remote_exec build "mv $debug_filename $hidden_filename"
+
+    # Create the build-id based directory in which the debug information
+    # will be placed.
+    set build_id_filename \
+	$debug_directory/[build_id_debug_filename_get $binfile]
+    remote_exec build "mkdir -p [file dirname $build_id_filename]"
+
+    # Configure the handler to move the debug info into the build-id dir.
+    gdb_test_no_output "python handler_obj.set_mode(Mode.RETURN_TRUE, \
+						    \"$hidden_filename\", \
+						    \"$build_id_filename\")" \
+	"confirgure handler"
+
+    # Reload the binary and check the debug information is found.
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "debug"} "debug info found"
+
+    # Check the handler was only called once.
+    gdb_test "python print(handler_obj.call_count)" "^1" \
+	"check handler was only called once"
+}
+
+# Move the debug information back to a hidden location and configure the
+# handler to return the filename of the hidden debug info location.  GDB
+# should immediately use this file as the debug information.
+with_test_prefix "handler returning a string" {
+    remote_exec build "mv $build_id_filename $hidden_filename"
+
+    # Configure the handler return a filename string.
+    gdb_test_no_output "python handler_obj.set_mode(Mode.RETURN_STRING, \
+						    \"$hidden_filename\")" \
+	"confirgure handler"
+
+    # Reload the binary and check the debug information is found.
+    gdb_file_cmd $binfile
+    gdb_assert {$gdb_file_cmd_debug_info == "debug"} "debug info found"
+
+    # Check the handler was only called once.
+    gdb_test "python print(handler_obj.call_count)" "^1" \
+	"check handler was only called once"
+}
+
+# Register another global handler, this one raises an exception.  Reload the
+# debug information, the bad handler should be invoked first, which raises
+# an excetption, at which point GDB should skip further Python handlers.
+with_test_prefix "handler raises an exception" {
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(None, rhandler)"
+
+    foreach_with_prefix exception_type {gdb.GdbError TypeError} {
+	gdb_test_no_output \
+	    "python rhandler.exception_type = $exception_type"
+
+	gdb_file_cmd $binfile
+	gdb_assert {$gdb_file_cmd_debug_info == "nodebug"} \
+	    "debug info not found"
+
+	set re [string_to_regexp \
+		    "Python Exception <class '$exception_type'>: message"]
+	gdb_assert {[regexp $re $gdb_file_cmd_msg]} \
+	    "check for exception in file command output"
+
+	# Our original handler is still registered, but should not have been
+	# called again (as the exception occurs first).
+	gdb_test "python print(handler_obj.call_count)" "^1" \
+	    "check good handler hasn't been called again"
+    }
+}
+
+gdb_test "info missing-debug-handlers" \
+    [multi_line \
+	 "Global:" \
+	 "  exception_handler" \
+	 "  handler"] \
+    "check both handlers are visible"
+
+# Re-start GDB.
+clean_restart
+
+# Load the Python script into GDB.
+gdb_test "source $remote_python_file" "^Success" \
+    "source python script for bad handler name checks"
+
+# Attempt to register a missing-debug-handler with NAME.  The expectation is
+# that this should fail as NAME contains some invalid characters.
+proc check_bad_name {name} {
+    set name_re [string_to_regexp $name]
+    set re \
+	[multi_line \
+	     "ValueError: invalid character '.' in handler name: $name_re" \
+	     "Error while executing Python code\\."]
+
+    gdb_test "python register(\"$name\")" $re \
+	"check that '$name' is not accepted"
+}
+
+# We don't attempt to be exhaustive here, just check a few random examples
+# of invalid names.
+check_bad_name "!! Bad Name"
+check_bad_name "Bad Name"
+check_bad_name "(Bad Name)"
+check_bad_name "Bad \[Name\]"
+check_bad_name "Bad,Name"
+check_bad_name "Bad;Name"
+
+# Check that there are no handlers registered.
+gdb_test_no_output "info missing-debug-handlers" \
+    "check no handlers are registered"
+
+# Check we can use the enable/disable commands where there are no handlers
+# registered.
+gdb_test "enable missing-debug-handler foo" \
+    "^0 missing debug handlers enabled"
+gdb_test "disable missing-debug-handler foo" \
+    "^0 missing debug handlers disabled"
+
+# Grab the current program space object, used for registering handler later.
+gdb_test_no_output "python pspace = gdb.selected_inferior().progspace"
+
+# Now register some handlers.
+foreach hspec {{\"Foo\" None}
+    {\"-bar\" None}
+    {\"baz-\" pspace}
+    {\"abc-def\" pspace}} {
+    lassign $hspec name locus
+    gdb_test "python register($name, $locus)"
+}
+
+with_test_prefix "all handlers enabled" {
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Current Progspace:" \
+	     "  abc-def" \
+	     "  baz-" \
+	     "Global:" \
+	     "  -bar" \
+	     "  Foo"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def', 'baz-', '-bar', 'Foo']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "disable 'baz-'" {
+    gdb_test "disable missing-debug-handler progspace baz-" \
+	"^1 missing debug handler disabled"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def" \
+	     "  baz- \\\[disabled\\\]" \
+	     "Global:" \
+	     "  -bar" \
+	     "  Foo"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def', '-bar', 'Foo']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "disable 'Foo'" {
+    gdb_test "disable missing-debug-handler .* Foo" \
+	"^1 missing debug handler disabled"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def" \
+	     "  baz- \\\[disabled\\\]" \
+	     "Global:" \
+	     "  -bar" \
+	     "  Foo \\\[disabled\\\]"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def', '-bar']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "disable everything" {
+    gdb_test "disable missing-debug-handler .* .*" \
+	"^2 missing debug handlers disabled"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def \\\[disabled\\\]" \
+	     "  baz- \\\[disabled\\\]" \
+	     "Global:" \
+	     "  -bar \\\[disabled\\\]" \
+	     "  Foo \\\[disabled\\\]"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {[]}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "enable 'abc-def'" {
+    set re [string_to_regexp $binfile]
+
+    gdb_test "enable missing-debug-handler \"$re\" abc-def" \
+	"^1 missing debug handler enabled"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def" \
+	     "  baz- \\\[disabled\\\]" \
+	     "Global:" \
+	     "  -bar \\\[disabled\\\]" \
+	     "  Foo \\\[disabled\\\]"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "enable global handlers" {
+    set re [string_to_regexp $binfile]
+
+    gdb_test "enable missing-debug-handler global" \
+	"^2 missing debug handlers enabled"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def" \
+	     "  baz- \\\[disabled\\\]" \
+	     "Global:" \
+	     "  -bar" \
+	     "  Foo"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def', '-bar', 'Foo']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+# Add handler_obj to the global handler list, and configure it to
+# return False.  We should call all of the program space specific
+# handlers (which return None), and then call handler_obj from the
+# global list, which returns False, at which point we shouldn't call
+# anyone else.
+with_test_prefix "return False handler in progspace list" {
+    gdb_test "enable missing-debug-handler progspace" \
+	"^1 missing debug handler enabled"
+
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(None, handler_obj)" \
+	"register the initial handler"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  abc-def" \
+	     "  baz-" \
+	     "Global:" \
+	     "  handler" \
+	     "  -bar" \
+	     "  Foo"]
+
+    gdb_test_no_output "python handler_obj.set_mode(Mode.RETURN_FALSE)" \
+	"confirgure handler"
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['abc-def', 'baz-', 'handler']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+# Now add handler_obj to the current program space's handler list.  We
+# use the same handler object here, that's fine.  We should only see a
+# call to the first handler object in the call log.
+with_test_prefix "return False handler in global list" {
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(pspace, handler_obj)" \
+	"register the initial handler"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  handler" \
+	     "  abc-def" \
+	     "  baz-" \
+	     "Global:" \
+	     "  handler" \
+	     "  -bar" \
+	     "  Foo"]
+
+    gdb_file_cmd $binfile
+    gdb_test "python print(handler_call_log)" \
+	[string_to_regexp {['handler']}]
+    gdb_test_no_output "python handler_call_log = \[\]" \
+	"reset call log"
+}
+
+with_test_prefix "check handler replacement" {
+    # First, check we can have the same name appear in both program
+    # space and global lists without giving an error.
+    gdb_test_no_output "python register(\"Foo\", pspace)"
+
+    gdb_test "info missing-debug-handlers" \
+	[multi_line \
+	     "Progspace \[^\r\n\]+:" \
+	     "  Foo" \
+	     "  handler" \
+	     "  abc-def" \
+	     "  baz-" \
+	     "Global:" \
+	     "  handler" \
+	     "  -bar" \
+	     "  Foo"]
+
+    # Now check that we get an error if we try to add a handler with
+    # the same name.
+    gdb_test "python gdb.missing_debug.register_handler(pspace, log_handler(\"Foo\"))" \
+	[multi_line \
+	     "RuntimeError: Handler Foo already exists\\." \
+	     "Error while executing Python code\\."]
+
+    gdb_test "python gdb.missing_debug.register_handler(handler=log_handler(\"Foo\"), locus=pspace)" \
+	[multi_line \
+	     "RuntimeError: Handler Foo already exists\\." \
+	     "Error while executing Python code\\."]
+
+    # And now try again, but this time with 'replace=True', we
+    # shouldn't get an error in this case.
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(pspace, log_handler(\"Foo\"), replace=True)"
+
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(handler=log_handler(\"Foo\"), locus=None, replace=True)"
+
+    # Now disable a handler and check we still need to use 'replace=True'.
+    gdb_test "disable missing-debug-handler progspace Foo" \
+	"^1 missing debug handler disabled"
+
+    gdb_test "python gdb.missing_debug.register_handler(pspace, log_handler(\"Foo\"))" \
+	[multi_line \
+	     "RuntimeError: Handler Foo already exists\\." \
+	     "Error while executing Python code\\."] \
+	"still get an error when handler is disabled"
+
+    gdb_test_no_output \
+	"python gdb.missing_debug.register_handler(pspace, log_handler(\"Foo\"), replace=True)" \
+	"can replace a disabled handler"
+}
diff --git a/gdb/testsuite/gdb.python/py-missing-debug.py b/gdb/testsuite/gdb.python/py-missing-debug.py
new file mode 100644
index 0000000..720648e
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-missing-debug.py
@@ -0,0 +1,120 @@
+# Copyright (C) 2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import gdb
+from gdb.missing_debug import MissingDebugHandler
+from enum import Enum
+import os
+
+# A global log that is filled in by instances of the LOG_HANDLER class
+# when they are called.
+handler_call_log = []
+
+
+class Mode(Enum):
+    RETURN_NONE = 0
+    RETURN_TRUE = 1
+    RETURN_FALSE = 2
+    RETURN_STRING = 3
+
+
+class handler(MissingDebugHandler):
+    def __init__(self):
+        super().__init__("handler")
+        self._call_count = 0
+        self._mode = Mode.RETURN_NONE
+
+    def __call__(self, objfile):
+        global handler_call_log
+        handler_call_log.append(self.name)
+        self._call_count += 1
+        if self._mode == Mode.RETURN_NONE:
+            return None
+
+        if self._mode == Mode.RETURN_TRUE:
+            os.rename(self._src, self._dest)
+            return True
+
+        if self._mode == Mode.RETURN_FALSE:
+            return False
+
+        if self._mode == Mode.RETURN_STRING:
+            return self._dest
+
+        assert False
+
+    @property
+    def call_count(self):
+        """Return a count, the number of calls to __call__ since the last
+        call to set_mode.
+        """
+        return self._call_count
+
+    def set_mode(self, mode, *args):
+        self._call_count = 0
+        self._mode = mode
+
+        if mode == Mode.RETURN_NONE:
+            assert len(args) == 0
+            return
+
+        if mode == Mode.RETURN_TRUE:
+            assert len(args) == 2
+            self._src = args[0]
+            self._dest = args[1]
+            return
+
+        if mode == Mode.RETURN_FALSE:
+            assert len(args) == 0
+            return
+
+        if mode == Mode.RETURN_STRING:
+            assert len(args) == 1
+            self._dest = args[0]
+            return
+
+        assert False
+
+
+class exception_handler(MissingDebugHandler):
+    def __init__(self):
+        super().__init__("exception_handler")
+        self.exception_type = None
+
+    def __call__(self, objfile):
+        global handler_call_log
+        handler_call_log.append(self.name)
+        assert self.exception_type is not None
+        raise self.exception_type("message")
+
+
+class log_handler(MissingDebugHandler):
+    def __call__(self, objfile):
+        global handler_call_log
+        handler_call_log.append(self.name)
+        return None
+
+
+# A basic helper function, this keeps lines shorter in the TCL script.
+def register(name, locus=None):
+    gdb.missing_debug.register_handler(locus, log_handler(name))
+
+
+# Create instances of the handlers, but don't install any.  We install
+# these as needed from the TCL script.
+rhandler = exception_handler()
+handler_obj = handler()
+
+print("Success")