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gdb: implement missing debug handler hook for Python

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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>
This commit is contained in:
Andrew Burgess 2023-10-15 22:48:42 +01:00
parent 661d98a333
commit 8f6c452b5a
11 changed files with 1352 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

26
gdb/NEWS
View file

@ -16,6 +16,21 @@ disassemble
command will now give an error. Previously the 'b' flag would
always override the 'r' flag.
* New Commands
info missing-debug-handler
List all the registered missing debug handlers.
enable missing-debug-handler LOCUS HANDLER
disable missing-debug-handler LOCUS HANDLER
Enable or disable a missing debug handler with a name matching the
regular expression HANDLER, in LOCUS.
LOCUS can be 'global' to operate on global missing debug handler,
'progspace' to operate on handlers within the current program space,
or can be a regular expression which is matched against the filename
of the primary executable in each program space.
* Python API
** New function gdb.notify_mi(NAME, DATA), that emits custom
@ -24,6 +39,17 @@ disassemble
** New read/write attribute gdb.Value.bytes that contains a bytes
object holding the contents of this value.
** New module gdb.missing_debug that facilitates dealing with
objfiles that are missing any debug information.
** New function gdb.missing_debug.register_handler that can register
an instance of a sub-class of gdb.missing_debug.MissingDebugInfo
as a handler for objfiles that are missing debug information.
** New class gdb.missing_debug.MissingDebugInfo which can be
sub-classed to create handlers for objfiles with missing debug
information.
* New commands
maintenance info linux-lwps

2
gdb/data-directory/Makefile.in
View file

@ -73,6 +73,7 @@ PYTHON_FILE_LIST = \
gdb/FrameDecorator.py \
gdb/FrameIterator.py \
gdb/frames.py \
gdb/missing_debug.py \
gdb/printing.py \
gdb/prompt.py \
gdb/styling.py \
@ -82,6 +83,7 @@ PYTHON_FILE_LIST = \
gdb/command/__init__.py \
gdb/command/explore.py \
gdb/command/frame_filters.py \
gdb/command/missing_debug.py \
gdb/command/pretty_printers.py \
gdb/command/prompt.py \
gdb/command/type_printers.py \

140
gdb/doc/python.texi
View file

@ -230,6 +230,7 @@ optional arguments while skipping others. Example:
* Connections In Python:: Python representation of connections.
* TUI Windows In Python:: Implementing new TUI windows.
* Disassembly In Python:: Instruction Disassembly In Python
* Missing Debug Info In Python:: Handle missing debug info from Python.
@end menu
@node Basic Python
@ -5252,6 +5253,12 @@ The @code{frame_filters} attribute is a dictionary of frame filter
objects. @xref{Frame Filter API}, for more information.
@end defvar
@defvar Progspace.missing_debug_handlers
The @code{missing_debug_handlers} attribute is a list of the missing
debug handler objects for this program space. @xref{Missing Debug
Info In Python}, for more information.
@end defvar
A program space has the following methods:
@defun Progspace.block_for_pc (pc)
@ -7819,6 +7826,139 @@ class NibbleSwapDisassembler(gdb.disassembler.Disassembler):
gdb.disassembler.register_disassembler(NibbleSwapDisassembler())
@end smallexample
@node Missing Debug Info In Python
@subsubsection Missing Debug Info In Python
@cindex python, handle missing debug information
When @value{GDBN} encounters a new objfile (@pxref{Objfiles In
Python}), e.g.@: the primary executable, or any shared libraries used
by the inferior, @value{GDBN} will attempt to load the corresponding
debug information for that objfile. The debug information might be
found within the objfile itself, or within a separate objfile which
@value{GDBN} will automatically locate and load.
Sometimes though, @value{GDBN} might not find any debug information
for an objfile, in this case the debugging experience will be
restricted.
If @value{GDBN} fails to locate any debug information for a particular
objfile, there is an opportunity for a Python extension to step in. A
Python extension can potentially locate the missing debug information
using some platform- or project-specific steps, and inform
@value{GDBN} of its location. Or a Python extension might provide
some platform- or project-specific advice to the user about how to
obtain the missing debug information.
A missing debug information Python extension consists of a handler
object which has the @code{name} and @code{enabled} attributes, and
implements the @code{__call__} method. When @value{GDBN} encounters
an objfile for which it is unable to find any debug information, it
invokes the @code{__call__} method. Full details of how handlers are
written can be found below.
@subheading The @code{gdb.missing_debug} Module
@value{GDBN} comes with a @code{gdb.missing_debug} module which
contains the following class and global function:
@deftp{class} gdb.missing_debug.MissingDebugHandler
@code{MissingDebugHandler} is a base class from which user-created
handlers can derive, though it is not required that handlers derive
from this class, so long as any user created handler has the
@code{name} and @code{enabled} attributes, and implements the
@code{__call__} method.
@defun MissingDebugHandler.__init__ (name)
The @var{name} is a string used to reference this missing debug
handler within some @value{GDBN} commands. Valid names consist of the
characters @code{[-_a-zA-Z0-9]}, creating a handler with an invalid
name raises a @code{ValueError} exception.
@end defun
@defun MissingDebugHandler.__call__ (objfile)
Sub-classes must override the @code{__call__} method. The
@var{objfile} argument will be a @code{gdb.Objfile}, this is the
objfile for which @value{GDBN} was unable to find any debug
information.
The return value from the @code{__call__} method indicates what
@value{GDBN} should do next. The possible return values are:
@itemize @bullet
@item @code{None}
This indicates that this handler could not help with @var{objfile},
@value{GDBN} should call any other registered handlers.
@item @code{True}
This indicates that this handler has installed the debug information
into a location where @value{GDBN} would normally expect to find it
when looking for separate debug information files (@pxref{Separate
Debug Files}). @value{GDBN} will repeat the normal lookup process,
which should now find the separate debug file.
If @value{GDBN} still doesn't find the separate debug information file
after this second attempt, then the Python missing debug information
handlers are not invoked a second time, this prevents a badly behaved
handler causing @value{GDBN} to get stuck in a loop. @value{GDBN}
will continue without any debug information for @var{objfile}.
@item @code{False}
This indicates that this handler has done everything that it intends
to do with @var{objfile}, but no separate debug information can be
found. @value{GDBN} will not call any other registered handlers for
@var{objfile}. @value{GDBN} will continue without debugging
information for @var{objfile}.
@item A string
The returned string should contain a filename. @value{GDBN} will not
call any further registered handlers, and will instead load the debug
information from the file identified by the returned filename.
@end itemize
Invoking the @code{__call__} method from this base class will raise a
@code{NotImplementedError} exception.
@end defun
@defvar MissingDebugHandler.name
A read-only attribute which is a string, the name of this handler
passed to the @code{__init__} method.
@end defvar
@defvar MissingDebugHandler.enabled
A modifiable attribute containing a boolean; when @code{True}, the
handler is enabled, and will be used by @value{GDBN}. When
@code{False}, the handler has been disabled, and will not be used.
@end defvar
@end deftp
@defun gdb.missing_debug.register_handler (locus, handler, replace=@code{False})
Register a new missing debug handler with @value{GDBN}.
@var{handler} is an instance of a sub-class of
@code{MissingDebugHandler}, or at least an instance of an object that
has the same attributes and methods as @code{MissingDebugHandler}.
@var{locus} specifies to which handler list to prepend @var{handler}.
It can be either a @code{gdb.Progspace} (@pxref{Progspaces In Python})
or @code{None}, in which case the handler is registered globally. The
newly registered @var{handler} will be called before any other handler
from the same locus. Two handlers in the same locus cannot have the
same name, an attempt to add a handler with an already existing name
raises an exception unless @var{replace} is @code{True}, in which case
the old handler is deleted and the new handler is prepended to the
selected handler list.
@value{GDBN} first calls the handlers for the current program space,
and then the globally registered handlers. As soon as a handler
returns a value other than @code{None}, no further handlers are called
for this objfile.
@end defun
@node Python Auto-loading
@subsection Python Auto-loading
@cindex Python auto-loading

41
gdb/python/lib/gdb/__init__.py
View file

@ -84,6 +84,8 @@ xmethods = []
frame_filters = {}
# Initial frame unwinders.
frame_unwinders = []
# Initial missing debug handlers.
missing_debug_handlers = []
def _execute_unwinders(pending_frame):
@ -291,3 +293,42 @@ class Thread(threading.Thread):
# threads.
with blocked_signals():
super().start()
def _handle_missing_debuginfo(objfile):
"""Internal function called from GDB to execute missing debug
handlers.
Run each of the currently registered, and enabled missing debug
handler objects for the current program space and then from the
global list. Stop after the first handler that returns a result
other than None.
Arguments:
objfile: A gdb.Objfile for which GDB could not find any debug
information.
Returns:
None: No debug information could be found for objfile.
False: A handler has done all it can with objfile, but no
debug information could be found.
True: Debug information might have been installed by a
handler, GDB should check again.
A string: This is the filename of a file containing the
required debug information.
"""
pspace = objfile.progspace
for handler in pspace.missing_debug_handlers:
if handler.enabled:
result = handler(objfile)
if result is not None:
return result
for handler in missing_debug_handlers:
if handler.enabled:
result = handler(objfile)
if result is not None:
return result
return None

226
gdb/python/lib/gdb/command/missing_debug.py Normal file
View file

@ -0,0 +1,226 @@
# Missing debug related commands.
#
# 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/>.
import gdb
import re
def validate_regexp(exp, idstring):
"""Compile exp into a compiler regular expression object.
Arguments:
exp: The string to compile into a re.Pattern object.
idstring: A string, what exp is a regexp for.
Returns:
A re.Pattern object representing exp.
Raises:
SyntaxError: If exp is an invalid regexp.
"""
try:
return re.compile(exp)
except SyntaxError:
raise SyntaxError("Invalid %s regexp: %s." % (idstring, exp))
def parse_missing_debug_command_args(arg):
"""Internal utility to parse missing debug handler command argv.
Arguments:
arg: The arguments to the command. The format is:
[locus-regexp [name-regexp]]
Returns:
A 2-tuple of compiled regular expressions.
Raises:
SyntaxError: an error processing ARG
"""
argv = gdb.string_to_argv(arg)
argc = len(argv)
if argc > 2:
raise SyntaxError("Too many arguments.")
locus_regexp = ""
name_regexp = ""
if argc >= 1:
locus_regexp = argv[0]
if argc >= 2:
name_regexp = argv[1]
return (
validate_regexp(locus_regexp, "locus"),
validate_regexp(name_regexp, "handler"),
)
class InfoMissingDebugHanders(gdb.Command):
"""GDB command to list missing debug handlers.
Usage: info missing-debug-handlers [LOCUS-REGEXP [NAME-REGEXP]]
LOCUS-REGEXP is a regular expression matching the location of the
handler. If it is omitted, all registered handlers from all
loci are listed. A locus can be 'global', 'progspace' to list
the handlers from the current progspace, or a regular expression
matching filenames of progspaces.
NAME-REGEXP is a regular expression to filter missing debug
handler names. If this omitted for a specified locus, then all
registered handlers in the locus are listed.
"""
def __init__(self):
super().__init__("info missing-debug-handlers", gdb.COMMAND_FILES)
def list_handlers(self, title, handlers, name_re):
"""Lists the missing debug handlers whose name matches regexp.
Arguments:
title: The line to print before the list.
handlers: The list of the missing debug handlers.
name_re: handler name filter.
"""
if not handlers:
return
print(title)
for handler in handlers:
if name_re.match(handler.name):
print(
" %s%s" % (handler.name, "" if handler.enabled else " [disabled]")
)
def invoke(self, arg, from_tty):
locus_re, name_re = parse_missing_debug_command_args(arg)
if locus_re.match("progspace") and locus_re.pattern != "":
cp = gdb.current_progspace()
self.list_handlers(
"Progspace %s:" % cp.filename, cp.missing_debug_handlers, name_re
)
for progspace in gdb.progspaces():
filename = progspace.filename or ""
if locus_re.match(filename):
if filename == "":
if progspace == gdb.current_progspace():
msg = "Current Progspace:"
else:
msg = "Progspace <no-file>:"
else:
msg = "Progspace %s:" % filename
self.list_handlers(
msg,
progspace.missing_debug_handlers,
name_re,
)
# Print global handlers last, as these are invoked last.
if locus_re.match("global"):
self.list_handlers("Global:", gdb.missing_debug_handlers, name_re)
def do_enable_handler1(handlers, name_re, flag):
"""Enable/disable missing debug handlers whose names match given regex.
Arguments:
handlers: The list of missing debug handlers.
name_re: Handler name filter.
flag: A boolean indicating if we should enable or disable.
Returns:
The number of handlers affected.
"""
total = 0
for handler in handlers:
if name_re.match(handler.name) and handler.enabled != flag:
handler.enabled = flag
total += 1
return total
def do_enable_handler(arg, flag):
"""Enable or disable missing debug handlers."""
(locus_re, name_re) = parse_missing_debug_command_args(arg)
total = 0
if locus_re.match("global"):
total += do_enable_handler1(gdb.missing_debug_handlers, name_re, flag)
if locus_re.match("progspace") and locus_re.pattern != "":
total += do_enable_handler1(
gdb.current_progspace().missing_debug_handlers, name_re, flag
)
for progspace in gdb.progspaces():
filename = progspace.filename or ""
if locus_re.match(filename):
total += do_enable_handler1(progspace.missing_debug_handlers, name_re, flag)
print(
"%d missing debug handler%s %s"
% (total, "" if total == 1 else "s", "enabled" if flag else "disabled")
)
class EnableMissingDebugHandler(gdb.Command):
"""GDB command to enable missing debug handlers.
Usage: enable missing-debug-handler [LOCUS-REGEXP [NAME-REGEXP]]
LOCUS-REGEXP is a regular expression specifying the handlers to
enable. It can be 'global', 'progspace' for the current
progspace, or the filename for a file associated with a progspace.
NAME_REGEXP is a regular expression to filter handler names. If
this omitted for a specified locus, then all registered handlers
in the locus are affected.
"""
def __init__(self):
super().__init__("enable missing-debug-handler", gdb.COMMAND_FILES)
def invoke(self, arg, from_tty):
"""GDB calls this to perform the command."""
do_enable_handler(arg, True)
class DisableMissingDebugHandler(gdb.Command):
"""GDB command to disable missing debug handlers.
Usage: disable missing-debug-handler [LOCUS-REGEXP [NAME-REGEXP]]
LOCUS-REGEXP is a regular expression specifying the handlers to
enable. It can be 'global', 'progspace' for the current
progspace, or the filename for a file associated with a progspace.
NAME_REGEXP is a regular expression to filter handler names. If
this omitted for a specified locus, then all registered handlers
in the locus are affected.
"""
def __init__(self):
super().__init__("disable missing-debug-handler", gdb.COMMAND_FILES)
def invoke(self, arg, from_tty):
"""GDB calls this to perform the command."""
do_enable_handler(arg, False)
def register_missing_debug_handler_commands():
"""Installs the missing debug handler commands."""
InfoMissingDebugHanders()
EnableMissingDebugHandler()
DisableMissingDebugHandler()
register_missing_debug_handler_commands()

169
gdb/python/lib/gdb/missing_debug.py Normal file
View file

@ -0,0 +1,169 @@
# 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/>.
"""
MissingDebugHandler base class, and register_handler function.
"""
import gdb
def _validate_name(name):
"""Validate a missing debug handler name string.
If name is valid as a missing debug handler name, then this
function does nothing. If name is not valid then an exception is
raised.
Arguments:
name: A string, the name of a missing debug handler.
Returns:
Nothing.
Raises:
ValueError: If name is invalid as a missing debug handler
name.
"""
for ch in name:
if not ch.isascii() or not (ch.isalnum() or ch in "_-"):
raise ValueError("invalid character '%s' in handler name: %s" % (ch, name))
class MissingDebugHandler(object):
"""Base class for missing debug handlers written in Python.
A missing debug handler has a single method __call__ along with
the read/write attribute enabled, and a read-only attribute name.
Attributes:
name: Read-only attribute, the name of this handler.
enabled: When true this handler is enabled.
"""
def __init__(self, name):
"""Constructor.
Args:
name: An identifying name for this handler.
Raises:
TypeError: name is not a string.
ValueError: name contains invalid characters.
"""
if not isinstance(name, str):
raise TypeError("incorrect type for name: %s" % type(name))
_validate_name(name)
self._name = name
self._enabled = True
@property
def name(self):
return self._name
@property
def enabled(self):
return self._enabled
@enabled.setter
def enabled(self, value):
if not isinstance(value, bool):
raise TypeError("incorrect type for enabled attribute: %s" % type(value))
self._enabled = value
def __call__(self, objfile):
"""GDB handle missing debug information for an objfile.
Arguments:
objfile: A gdb.Objfile for which GDB could not find any
debug information.
Returns:
True: GDB should try again to locate the debug information
for objfile, the handler may have installed the
missing information.
False: GDB should move on without the debug information
for objfile.
A string: GDB should load the file at the given path; it
contains the debug information for objfile.
None: This handler can't help with objfile. GDB should
try any other registered handlers.
"""
raise NotImplementedError("MissingDebugHandler.__call__()")
def register_handler(locus, handler, replace=False):
"""Register handler in given locus.
The handler is prepended to the locus's missing debug handlers
list. The name of handler should be unique (or replace must be
True).
Arguments:
locus: Either a progspace, or None (in which case the unwinder
is registered globally).
handler: An object of a gdb.MissingDebugHandler subclass.
replace: If True, replaces existing handler with the same name
within locus. Otherwise, raises RuntimeException if
unwinder with the same name already exists.
Returns:
Nothing.
Raises:
RuntimeError: The name of handler is not unique.
TypeError: Bad locus type.
AttributeError: Required attributes of handler are missing.
"""
if locus is None:
if gdb.parameter("verbose"):
gdb.write("Registering global %s handler ...\n" % handler.name)
locus = gdb
elif isinstance(locus, gdb.Progspace):
if gdb.parameter("verbose"):
gdb.write(
"Registering %s handler for %s ...\n" % (handler.name, locus.filename)
)
else:
raise TypeError("locus should be gdb.Progspace or None")
# Some sanity checks on HANDLER. Calling getattr will raise an
# exception if the attribute doesn't exist, which is what we want.
# These checks are not exhaustive; we don't check the attributes
# have the correct types, or the method has the correct signature,
# but this should catch some basic mistakes.
getattr(handler, "name")
getattr(handler, "enabled")
call_method = getattr(handler, "__call__")
if not callable(call_method):
raise AttributeError(
"'%s' object's '__call__' attribute is not callable"
% type(handler).__name__
)
i = 0
for needle in locus.missing_debug_handlers:
if needle.name == handler.name:
if replace:
del locus.missing_debug_handlers[i]
else:
raise RuntimeError("Handler %s already exists." % handler.name)
i += 1
locus.missing_debug_handlers.insert(0, handler)

51
gdb/python/py-progspace.c
View file

@ -55,6 +55,9 @@ struct pspace_object
/* The debug method list. */
PyObject *xmethods;
/* The missing debug handler list. */
PyObject *missing_debug_handlers;
};
extern PyTypeObject pspace_object_type
@ -164,6 +167,7 @@ pspy_dealloc (PyObject *self)
Py_XDECREF (ps_self->frame_unwinders);
Py_XDECREF (ps_self->type_printers);
Py_XDECREF (ps_self->xmethods);
Py_XDECREF (ps_self->missing_debug_handlers);
Py_TYPE (self)->tp_free (self);
}
@ -199,6 +203,10 @@ pspy_initialize (pspace_object *self)
if (self->xmethods == NULL)
return 0;
self->missing_debug_handlers = PyList_New (0);
if (self->missing_debug_handlers == nullptr)
return 0;
return 1;
}
@ -353,6 +361,47 @@ pspy_get_xmethods (PyObject *o, void *ignore)
return self->xmethods;
}
/* Return the list of missing debug handlers for this program space. */
static PyObject *
pspy_get_missing_debug_handlers (PyObject *o, void *ignore)
{
pspace_object *self = (pspace_object *) o;
Py_INCREF (self->missing_debug_handlers);
return self->missing_debug_handlers;
}
/* Set this program space's list of missing debug handlers to HANDLERS. */
static int
pspy_set_missing_debug_handlers (PyObject *o, PyObject *handlers,
void *ignore)
{
pspace_object *self = (pspace_object *) o;
if (handlers == nullptr)
{
PyErr_SetString (PyExc_TypeError,
"cannot delete the missing debug handlers list");
return -1;
}
if (!PyList_Check (handlers))
{
PyErr_SetString (PyExc_TypeError,
"the missing debug handlers attribute must be a list");
return -1;
}
/* Take care in case the LHS and RHS are related somehow. */
gdbpy_ref<> tmp (self->missing_debug_handlers);
Py_INCREF (handlers);
self->missing_debug_handlers = handlers;
return 0;
}
/* Set the 'type_printers' attribute. */
static int
@ -745,6 +794,8 @@ static gdb_PyGetSetDef pspace_getset[] =
"Type printers.", NULL },
{ "xmethods", pspy_get_xmethods, NULL,
"Debug methods.", NULL },
{ "missing_debug_handlers", pspy_get_missing_debug_handlers,
pspy_set_missing_debug_handlers, "Missing debug handlers.", NULL },
{ NULL }
};

81
gdb/python/python.c
View file

@ -128,6 +128,8 @@ static gdb::optional<std::string> gdbpy_colorize
(const std::string &filename, const std::string &contents);
static gdb::optional<std::string> gdbpy_colorize_disasm
(const std::string &content, gdbarch *gdbarch);
static ext_lang_missing_debuginfo_result gdbpy_handle_missing_debuginfo
(const struct extension_language_defn *extlang, struct objfile *objfile);
/* The interface between gdb proper and loading of python scripts. */
@ -173,6 +175,8 @@ static const struct extension_language_ops python_extension_ops =
gdbpy_colorize_disasm,
gdbpy_print_insn,
gdbpy_handle_missing_debuginfo
};
#endif /* HAVE_PYTHON */
@ -1688,6 +1692,83 @@ gdbpy_get_current_objfile (PyObject *unused1, PyObject *unused2)
return objfile_to_objfile_object (gdbpy_current_objfile).release ();
}
/* Implement the 'handle_missing_debuginfo' hook for Python. GDB has
failed to find any debug information for OBJFILE. The extension has a
chance to record this, or even install the required debug information.
See the description of ext_lang_missing_debuginfo_result in
extension-priv.h for details of the return value. */
static ext_lang_missing_debuginfo_result
gdbpy_handle_missing_debuginfo (const struct extension_language_defn *extlang,
struct objfile *objfile)
{
/* Early exit if Python is not initialised. */
if (!gdb_python_initialized)
return {};
struct gdbarch *gdbarch = objfile->arch ();
gdbpy_enter enter_py (gdbarch);
/* Convert OBJFILE into the corresponding Python object. */
gdbpy_ref<> pyo_objfile = objfile_to_objfile_object (objfile);
if (pyo_objfile == nullptr)
{
gdbpy_print_stack ();
return {};
}
/* Lookup the helper function within the GDB module. */
gdbpy_ref<> pyo_handler
(PyObject_GetAttrString (gdb_python_module, "_handle_missing_debuginfo"));
if (pyo_handler == nullptr)
{
gdbpy_print_stack ();
return {};
}
/* Call the function, passing in the Python objfile object. */
gdbpy_ref<> pyo_execute_ret
(PyObject_CallFunctionObjArgs (pyo_handler.get (), pyo_objfile.get (),
nullptr));
if (pyo_execute_ret == nullptr)
{
/* If the handler is cancelled due to a Ctrl-C, then propagate
the Ctrl-C as a GDB exception instead of swallowing it. */
gdbpy_print_stack_or_quit ();
return {};
}
/* Parse the result, and convert it back to the C++ object. */
if (pyo_execute_ret == Py_None)
return {};
if (PyBool_Check (pyo_execute_ret.get ()))
{
bool try_again = PyObject_IsTrue (pyo_execute_ret.get ());
return ext_lang_missing_debuginfo_result (try_again);
}
if (!gdbpy_is_string (pyo_execute_ret.get ()))
{
PyErr_SetString (PyExc_ValueError,
"return value from _handle_missing_debuginfo should "
"be None, a Bool, or a String");
gdbpy_print_stack ();
return {};
}
gdb::unique_xmalloc_ptr<char> filename
= python_string_to_host_string (pyo_execute_ret.get ());
if (filename == nullptr)
{
gdbpy_print_stack ();
return {};
}
return ext_lang_missing_debuginfo_result (std::string (filename.get ()));
}
/* Compute the list of active python type printers and store them in
EXT_PRINTERS->py_type_printers. The product of this function is used by
gdbpy_apply_type_printers, and freed by gdbpy_free_type_printers.

22
gdb/testsuite/gdb.python/py-missing-debug.c Normal file
View file

@ -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;
}

473
gdb/testsuite/gdb.python/py-missing-debug.exp Normal file
View file

@ -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"
}

120
gdb/testsuite/gdb.python/py-missing-debug.py Normal file
View file

@ -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")