The DAP code already claimed to implement "scopes" and "evaluate", but
this wasn't done completely correctly. This patch implements these
and also implements the "variables" request.
After this patch, variables and scopes correctly report their
sub-structure. This also interfaces with the gdb pretty-printer API,
so the output of pretty-printers is available.
Tom de Vries pointed out that one DAP test failed on Python 3.6
because gdb.Frame is not hashable.
This patch fixes the problem by using a list to hold the frames. This
is less efficient but there normally won't be that many frames.
Tested-by: Tom de Vries <tdevries@suse.de>
Linetables no longer change after they are created. This patch
applies const to them.
Note there is one hack to cast away const in mdebugread.c. This code
allocates a linetable using 'malloc', then later copies it to the
obstack. While this could be cleaned up, I chose not to do so because
I have no way of testing it.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes linetables to not add the text offset to the addresses
they contain. I did this in a few steps, necessarily combined
together in one patch: I renamed the 'pc' member to 'm_pc', added the
appropriate accessors, and then recompiled. Then I fixed all the
errors. Where possible I generally chose to use the raw_pc accessor,
as it is less expensive.
Note that this patch discounts the possibility that the text section
offset might cause wraparound in the addresses in the line table.
However, this was already discounted -- in particular,
objfile_relocate1 did not re-sort the table in this scenario. (There
was a bug open about this, but as far as I can tell this has never
happened, it's not even clear what inspired that bug.)
Approved-By: Simon Marchi <simon.marchi@efficios.com>
As of 2023-02-13 "gdb/python: deallocate tui window factories at Python
shut down" (9ae4519da9), a TUI-less build fails with:
$src/gdb/python/py-tui.c: In function ‘void gdbpy_finalize_tui()’:
$src/gdb/python/py-tui.c:621:3: error: ‘gdbpy_tui_window_maker’ has not been declared
621 | gdbpy_tui_window_maker::invalidate_all ();
| ^~~~~~~~~~~~~~~~~~~~~~
Since gdbpy_tui_window_maker is only defined under #ifdef TUI, add an
#ifdef guard in gdbpy_finalize_tui as well.
The DAP stackTrace implementation did not fully account for frames
without debuginfo. Attemping this would yield a result like:
{"request_seq": 5, "type": "response", "command": "stackTrace", "success": false, "message": "'NoneType' object has no attribute 'filename'", "seq": 11}
This patch fixes the problem by adding another check for None.
Small cleanup to use std::string::size instead of calling strlen on
the result of std::string::c_str.
Should be no user visible changes after this call.
The copyright years in the ROCm files (e.g. solib-rocm.c) are wrong,
they end in 2022 instead of 2023. I suppose because I posted (or at
least prepared) the patches in 2022 but merged them in 2023, and forgot
to update the year. I found a bunch of other files that are in the same
situation. Fix them all up.
Change-Id: Ia55f5b563606c2ba6a89046f22bc0bf1c0ff2e10
Reviewed-By: Tom Tromey <tom@tromey.com>
Background
----------
When a thread-specific breakpoint is deleted as a result of the
specific thread exiting the function remove_threaded_breakpoints is
called which sets the disposition of the breakpoint to
disp_del_at_next_stop and sets the breakpoint number to 0. Setting
the breakpoint number to zero has the effect of hiding the breakpoint
from the user. We also print a message indicating that the breakpoint
has been deleted.
It was brought to my attention during a review of another patch[1]
that setting a breakpoints number to zero will suppress the MI
breakpoint-deleted notification for that breakpoint, and indeed, this
can be seen to be true, in delete_breakpoint, if the breakpoint number
is zero, then GDB will not notify the breakpoint_deleted observer.
It seems wrong that a user created, thread-specific breakpoint, will
have a =breakpoint-created notification, but will not have a
=breakpoint-deleted notification. I suspect that this is a bug.
[1] https://sourceware.org/pipermail/gdb-patches/2023-February/196560.html
The First Problem
-----------------
During my initial testing I wanted to see how GDB handled the
breakpoint after it's number was set to zero. To do this I created
the testcase gdb.threads/thread-bp-deleted.exp. This test creates a
worker thread, which immediately exits. After the worker thread has
exited the main thread spins in a loop.
In GDB I break once the worker thread has been created and place a
thread-specific breakpoint, then use 'continue&' to resume the
inferior in non-stop mode. The worker thread then exits, but the main
thread never stops - instead it sits in the spin. I then tried to use
'maint info breakpoints' to see what GDB thought of the
thread-specific breakpoint.
Unfortunately, GDB crashed like this:
(gdb) continue&
Continuing.
(gdb) [Thread 0x7ffff7c5d700 (LWP 1202458) exited]
Thread-specific breakpoint 3 deleted - thread 2 no longer in the thread list.
maint info breakpoints
... snip some output ...
Fatal signal: Segmentation fault
----- Backtrace -----
0x5ffb62 gdb_internal_backtrace_1
../../src/gdb/bt-utils.c:122
0x5ffc05 _Z22gdb_internal_backtracev
../../src/gdb/bt-utils.c:168
0x89965e handle_fatal_signal
../../src/gdb/event-top.c:964
0x8997ca handle_sigsegv
../../src/gdb/event-top.c:1037
0x7f96f5971b1f ???
/usr/src/debug/glibc-2.30-2-gd74461fa34/nptl/../sysdeps/unix/sysv/linux/x86_64/sigaction.c:0
0xe602b0 _Z15print_thread_idP11thread_info
../../src/gdb/thread.c:1439
0x5b3d05 print_one_breakpoint_location
../../src/gdb/breakpoint.c:6542
0x5b462e print_one_breakpoint
../../src/gdb/breakpoint.c:6702
0x5b5354 breakpoint_1
../../src/gdb/breakpoint.c:6924
0x5b58b8 maintenance_info_breakpoints
../../src/gdb/breakpoint.c:7009
... etc ...
As the thread-specific breakpoint is set to disp_del_at_next_stop, and
GDB hasn't stopped yet, then the breakpoint still exists in the global
breakpoint list.
The breakpoint will not show in 'info breakpoints' as its number is
zero, but it will show in 'maint info breakpoints'.
As GDB prints the breakpoint, the thread-id for the breakpoint is
printed as part of the 'stop only in thread ...' line. Printing the
thread-id involves calling find_thread_global_id to convert the global
thread-id into a thread_info*. Then calling print_thread_id to
convert the thread_info* into a string.
The problem is that find_thread_global_id returns nullptr as the
thread for the thread-specific breakpoint has exited. The
print_thread_id assumes it will be passed a non-nullptr. As a result
GDB crashes.
In this commit I've added an assert to print_thread_id (gdb/thread.c)
to check that the pointed passed in is not nullptr. This assert would
have triggered in the above case before GDB crashed.
MI Notifications: The Dangers Of Changing A Breakpoint's Number
---------------------------------------------------------------
Currently the delete_breakpoint function doesn't trigger the
breakpoint_deleted observer for any breakpoint with the number zero.
There is a comment explaining why this is the case in the code; it's
something about watchpoints. But I did consider just removing the 'is
the number zero' guard and always triggering the breakpoint_deleted
observer, figuring that I'd then fix the watchpoint issue some other
way.
But I realised this wasn't going to be good enough. When the MI
notification was delivered the number would be zero, so any frontend
parsing the notifications would not be able to match
=breakpoint-deleted notification to the earlier =breakpoint-created
notification.
What this means is that, at the point the breakpoint_deleted observer
is called, the breakpoint's number must be correct.
MI Notifications: The Dangers Of Delaying Deletion
--------------------------------------------------
The test I used to expose the above crash also brought another problem
to my attention. In the above test we used 'continue&' to resume,
after which a thread exited, but the inferior didn't stop. Recreating
the same test in the MI looks like this:
-break-insert -p 2 main
^done,bkpt={number="2",type="breakpoint",disp="keep",...<snip>...}
(gdb)
-exec-continue
^running
*running,thread-id="all"
(gdb)
~"[Thread 0x7ffff7c5d700 (LWP 987038) exited]\n"
=thread-exited,id="2",group-id="i1"
~"Thread-specific breakpoint 2 deleted - thread 2 no longer in the thread list.\n"
At this point the we have a single thread left, which is still
running:
-thread-info
^done,threads=[{id="1",target-id="Thread 0x7ffff7c5eb80 (LWP 987035)",name="thread-bp-delet",state="running",core="4"}],current-thread-id="1"
(gdb)
Notice that we got the =thread-exited notification from GDB as soon as
the thread exited. We also saw the CLI line from GDB, the line
explaining that breakpoint 2 was deleted. But, as expected, we didn't
see the =breakpoint-deleted notification.
I say "as expected" because the number was set to zero. But, even if
the number was not set to zero we still wouldn't see the
notification. The MI notification is driven by the breakpoint_deleted
observer, which is only called when we actually delete the breakpoint,
which is only done the next time GDB stops.
Now, maybe this is fine. The notification is delivered a little
late. But remember, by setting the number to zero the breakpoint will
be hidden from the user, for example, the breakpoint is removed from
the MI's -break-info command output.
This means that GDB is in a position where the breakpoint doesn't show
up in the breakpoint table, but a =breakpoint-deleted notification has
not yet been sent out. This doesn't seem right to me.
What this means is that, when the thread exits, we should immediately
be sending out the =breakpoint-deleted notification. We should not
wait for GDB to next stop before sending the notification.
The Solution
------------
My proposed solution is this; in remove_threaded_breakpoints, instead
of setting the disposition to disp_del_at_next_stop and setting the
number to zero, we now just call delete_breakpoint directly.
The notification will now be sent out immediately; as soon as the
thread exits.
As the number has not changed when delete_breakpoint is called, the
notification will have the correct number.
And as the breakpoint is immediately removed from the breakpoint list,
we no longer need to worry about 'maint info breakpoints' trying to
print the thread-id for an exited thread.
My only concern is that calling delete_breakpoint directly seems so
obvious that I wonder why the original patch (that added
remove_threaded_breakpoints) didn't take this approach. This code was
added in commit 49fa26b041, but the commit message offers no clues
to why this approach was taken, and the original email thread offers
no insights either[2]. There are no test regressions after making
this change, so I'm hopeful that this is going to be fine.
[2] https://sourceware.org/pipermail/gdb-patches/2013-September/106493.html
The Complication
----------------
Of course, it couldn't be that simple.
The script gdb.python/py-finish-breakpoint.exp had some regressions
during testing.
The problem was with the FinishBreakpoint.out_of_scope callback
implementation. This callback is supposed to trigger whenever the
FinishBreakpoint goes out of scope; and this includes when the thread
for the breakpoint exits.
The problem I ran into is the Python FinishBreakpoint implementation.
Specifically, after this change I was loosing some of the out_of_scope
calls.
The problem is that the out_of_scope call (of which I'm interested) is
triggered from the inferior_exit observer. Before my change the
observers were called in this order:
thread_exit
inferior_exit
breakpoint_deleted
The inferior_exit would trigger the out_of_scope call.
After my change the breakpoint_deleted notification (for
thread-specific breakpoints) occurs earlier, as soon as the
thread-exits, so now the order is:
thread_exit
breakpoint_deleted
inferior_exit
Currently, after the breakpoint_deleted call the Python object
associated with the breakpoint is released, so, when we get to the
inferior_exit observer, there's no longer a Python object to call the
out_of_scope method on.
My solution is to follow the model for how bpfinishpy_pre_stop_hook
and bpfinishpy_post_stop_hook are called, this is done from
gdbpy_breakpoint_cond_says_stop in py-breakpoint.c.
I've now added a new bpfinishpy_pre_delete_hook
gdbpy_breakpoint_deleted in py-breakpoint.c, and from this new hook
function I check and where needed call the out_of_scope method.
With this fix in place I now see the
gdb.python/py-finish-breakpoint.exp test fully passing again.
Testing
-------
Tested on x86-64/Linux with unix, native-gdbserver, and
native-extended-gdbserver boards.
New tests added to covers all the cases I've discussed above.
Approved-By: Pedro Alves <pedro@palves.net>
See the previous patches in this series for the motivation behind
these changes.
This commit contains updates to Python's QUIT handling. Ideally, we'd
like to throw gdb_exception_forced_quit through the extension
language; I made an attempt to do this for gdb_exception_quit in an
earlier version of this patch, but Pedro pointed out that it is
(almost certainly) not safe to do so.
Still, we definitely don't want to swallow the exception representing
a SIGTERM for GDB, nor do we want to force modules written in the
extension language to have to explicitly handle this case. Since the
idea is for GDB to cleanup and quit for this exception, we'll simply
call quit_force() just as if the gdb_exception_forced_quit propagation
had managed to make it back to the top level.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26761
Tested-by: Tom de Vries <tdevries@suse.de>
Approved-By: Pedro Alves <pedro@palves.net>
Hannes filed a bug showing a crash, where a pretty-printer written in
Python could cause a use-after-free. He sent a patch, but I thought a
different approach was needed.
In a much earlier patch (see bug #12533), we changed the Python code
to release new values from the value chain when constructing a
gdb.Value. The rationale for this is that if you write a command that
does a lot of computations in a loop, all the values will be kept live
by the value chain, resulting in gdb using a large amount of memory.
However, suppose a value is passed to Python from some code in gdb
that needs to use the value after the call into Python. In this
scenario, value_to_value_object will still release the value -- and
because gdb code doesn't generally keep strong references to values (a
consequence of the ancient decision to use the value chain to avoid
memory management), this will result in a use-after-free.
This scenario can happen, as it turns out, when a value is passed to
Python for pretty-printing. Now, normally this route boxes the value
via value_to_value_object_no_release, avoiding the problematic release
from the value chain. However, if you then call Value.cast, the
underlying value API might return the same value, when is then
released from the chain.
This patch fixes the problem by changing how value boxing is done.
value_to_value_object no longer removes a value from the chain.
Instead, every spot in gdb that might construct new values uses a
scoped_value_mark to ensure that the requirements of bug #12533 are
met. And, because incoming values aren't ever released from the chain
(the Value.cast one comes earlier on the chain than the
scoped_value_mark), the bug can no longer occur. (Note that many
spots in the Python layer already take this approach, so not many
places needed to be touched.)
In the future I think we should replace the use of raw "value *" with
value_ref_ptr pretty much everywhere. This will ensure lifetime
safety throughout gdb.
The test case in this patch comes from Hannes' original patch. I only
made a trivial ("require") change to it. However, while this fails
for him, I can't make it fail on this machine; nevertheless, he tried
my patch and reported the bug as being fixed.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30044
This converts block_static_block and block_global_block to be methods.
This was mostly written by script. It was simpler to convert them at
the same time because they're often used near each other.
This removes deprecated_lval_hack and the VALUE_LVAL macro, replacing
all uses with a call to value::lval.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes preserve_one_value to be a method of value. Much of this
patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns many functions that are related to optimized-out or
availability-checking to be methods of value. The static function
value_entirely_covered_by_range_vector is also converted to be a
private method.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns the remaining value_contents functions -- value_contents,
value_contents_all, value_contents_for_printing, and
value_contents_for_printing_const -- into methods of value. It also
converts the static functions require_not_optimized_out and
require_available to be private methods.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes value_incref and value_decref to be methods of value.
Much of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes value_fetch_lazy to be a method of value. A few helper
functions are converted as well, to avoid problems in later patches
when the data members are all made private.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes the value_lazy and set_value_lazy functions to be methods
of value. Much of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
The previous commit relied on spotting when a Python defined TUI
window factory was deleted. I spotted that the window factories are
not deleted when GDB shuts down its Python environment, they are only
deleted when one window factory replaces another. Consider this
example Python script:
class TestWindowFactory:
def __init__(self, msg):
self.msg = msg
print("Entering TestWindowFactory.__init__: %s" % self.msg)
def __call__(self, tui_win):
print("Entering TestWindowFactory.__call__: %s" % self.msg)
return TestWindow(tui_win, self.msg)
def __del__(self):
print("Entering TestWindowFactory.__del__: %s" % self.msg)
gdb.register_window_type("test_window", TestWindowFactory("A"))
gdb.register_window_type("test_window", TestWindowFactory("B"))
And this GDB session:
(gdb) source tui.py
Entering TestWindowFactory.__init__: A
Entering TestWindowFactory.__init__: B
Entering TestWindowFactory.__del__: B
(gdb) quit
Notice that when the 'B' window replaces the 'A' window we see the 'A'
object being deleted. But, when Python is shut down (after the
'quit') the 'B' object is never deleted.
Instead, GDB retains a reference to the window factory object, which
forces the Python object to remain live even after the Python
interpreter itself has been shut down.
The references themselves are held in a dynamically allocated
std::unordered_map (in tui/tui-layout.c) which is never deallocated,
thus the underlying Python references are never decremented to zero,
and so GDB never tries to delete these Python objects.
This commit is the first half of the work to clean up this edge case.
All gdbpy_tui_window_maker objects (the objects that implement the
TUI window factory callback for Python defined TUI windows), are now
linked together into a global list using the intrusive list mechanism.
When GDB shuts down the Python interpreter we can now walk this global
list and release the reference that is held to the underlying Python
object. By releasing this reference the Python object will now be
deleted.
I've added a new assert in gdbpy_tui_window_maker::operator(), this
will catch the case where we somehow end up in here after having
reset the reference to the underlying Python object. I don't think
this should ever happen though as we only clear the references when
shutting down the Python interpreter, and the ::operator() function is
only called when trying to apply a new TUI layout - something that
shouldn't happen while GDB itself is shutting down.
This commit does not update the std::unordered_map in tui-layout.c,
that will be done in the next commit.
Reviewed-By: Tom Tromey <tom@tromey.com>
Within the breakpoint struct we have two fields ::thread and ::task
which are used for thread or task specific breakpoints. When a
breakpoint doesn't have a specific thread or task then these fields
have the values -1 and 0 respectively.
There's no particular reason (as far as I can tell) why these two
"default" values are different, and I find the difference a little
confusing. Long term I'd like to potentially fold these two fields
into a single field, but that isn't what this commit does.
What this commit does is switch to using -1 as the "default" value for
both fields, this means that the default for breakpoint::task has
changed from 0 to -1. I've updated all the code I can find that
relied on the value of 0, and I see no test regressions, especially in
gdb.ada/tasks.exp, which still fully passes.
There should be no user visible changes after this commit.
Approved-By: Pedro Alves <pedro@palves.net>
After this mailing list posting:
https://sourceware.org/pipermail/gdb-patches/2023-February/196607.html
it seems to me that in practice an Ada task maps 1:1 with a GDB
thread, and so it doesn't really make sense to allow uses to give both
a thread and a task within a single breakpoint or watchpoint
condition.
This commit updates GDB so that the user will get an error if both
are specified.
I've added new tests to cover the CLI as well as the Python and Guile
APIs. For the Python and Guile testing, as far as I can tell, this
was the first testing for this corner of the APIs, so I ended up
adding more than just a single test.
For documentation I've added a NEWS entry, but I've not added anything
to the docs themselves. Currently we document the commands with a
thread-id or task-id as distinct command, e.g.:
'break LOCSPEC task TASKNO'
'break LOCSPEC task TASKNO if ...'
'break LOCSPEC thread THREAD-ID'
'break LOCSPEC thread THREAD-ID if ...'
As such, I don't believe there is any indication that combining 'task'
and 'thread' would be expected to work; it seems clear to me in the
above that those four options are all distinct commands.
I think the NEWS entry is enough that if someone is combining these
keywords (it's not clear what the expected behaviour would be in this
case) then they can figure out that this was a deliberate change in
GDB, but for a new user, the manual doesn't suggest combining them is
OK, and any future attempt to combine them will give an error.
Approved-By: Pedro Alves <pedro@palves.net>
Python functions implementing DAP requests should not use positional
parameters -- it only makes sense to call them with keyword arguments.
This patch changes the few remaining cases to start with the special
"*" parameter, following this rule.
This patch implements a simplication that I suggested here:
https://sourceware.org/pipermail/gdb-patches/2022-March/186320.html
Currently, the interp::exec virtual method interface is such that
subclass implementations must catch exceptions and then return them
via normal function return.
However, higher up the in chain, for the CLI we get to
interpreter_exec_cmd, which does:
for (i = 1; i < nrules; i++)
{
struct gdb_exception e = interp_exec (interp_to_use, prules[i]);
if (e.reason < 0)
{
interp_set (old_interp, 0);
error (_("error in command: \"%s\"."), prules[i]);
}
}
and for MI we get to mi_cmd_interpreter_exec, which has:
void
mi_cmd_interpreter_exec (const char *command, char **argv, int argc)
{
...
for (i = 1; i < argc; i++)
{
struct gdb_exception e = interp_exec (interp_to_use, argv[i]);
if (e.reason < 0)
error ("%s", e.what ());
}
}
Note that if those errors are reached, we lose the original
exception's error code. I can't see why we'd want that.
And, I can't see why we need to have interp_exec catch the exception
and return it via the normal return path. That's normally needed when
we need to handle propagating exceptions across C code, like across
readline or ncurses, but that's not the case here.
It seems to me that we can simplify things by removing some
try/catch-ing and just letting exceptions propagate normally.
Note, the "error in command" error shown above, which only exists in
the CLI interpreter-exec command, is only ever printed AFAICS if you
run "interpreter-exec console" when the top level interpreter is
already the console/tui. Like:
(gdb) interpreter-exec console "foobar"
Undefined command: "foobar". Try "help".
error in command: "foobar".
You won't see it with MI's "-interpreter-exec console" from a top
level MI interpreter:
(gdb)
-interpreter-exec console "foobar"
&"Undefined command: \"foobar\". Try \"help\".\n"
^error,msg="Undefined command: \"foobar\". Try \"help\"."
(gdb)
nor with MI's "-interpreter-exec mi" from a top level MI interpreter:
(gdb)
-interpreter-exec mi "-foobar"
^error,msg="Undefined MI command: foobar",code="undefined-command"
^done
(gdb)
in both these cases because MI's -interpreter-exec just does:
error ("%s", e.what ());
You won't see it either when running an MI command with the CLI's
"interpreter-exec mi":
(gdb) interpreter-exec mi "-foobar"
^error,msg="Undefined MI command: foobar",code="undefined-command"
(gdb)
This last case is because MI's interp::exec implementation never
returns an error:
gdb_exception
mi_interp::exec (const char *command)
{
mi_execute_command_wrapper (command);
return gdb_exception ();
}
Thus I think that "error in command" error is pretty pointless, and
since it simplifies things to not have it, the patch just removes it.
The patch also ends up addressing an old FIXME.
Change-Id: I5a6432a80496934ac7127594c53bf5221622e393
Approved-By: Tom Tromey <tromey@adacore.com>
Approved-By: Kevin Buettner <kevinb@redhat.com>
This helps resolve some cyclic include problem later in the series.
The only language-related thing frame.h needs is enum language, and that
is in defs.h.
Doing so reveals that a bunch of files were relying on frame.h to
include language.h, so fix the fallouts here and there.
Change-Id: I178a7efec1953c2d088adb58483bade1f349b705
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
This commit splits the `set/show print elements' option into two. We
retain `set/show print elements' for controlling how many elements of an
array we print, but a new `set/show print characters' setting is added
which is used for controlling how many characters of a string are
printed.
The motivation behind this change is to allow users a finer level of
control over how data is printed, reflecting that, although strings can
be thought of as arrays of characters, users often want to treat these
two things differently.
For compatibility reasons by default the `set/show print characters'
option is set to `elements', which makes the limit for character strings
follow the setting of the `set/show print elements' option, as it used
to. Using `set print characters' with any other value makes the limit
independent from the `set/show print elements' setting, however it can
be restored to the default with the `set print characters elements'
command at any time.
A corresponding `-characters' option for the `print' command is added,
with the same semantics, i.e. one can use `elements' to make a given
`print' invocation follow the limit of elements, be it set with the
`-elements' option also given with the same invocation or taken from the
`set/show print elements' setting, for characters as well regardless of
the current setting of the `set/show print characters' option.
The GDB changes are all pretty straightforward, just changing references
to the old 'print_max' to use a new `get_print_max_chars' helper which
figures out which of the two of `print_max' and `print_max_chars' values
to use.
Likewise, the documentation is just updated to reference the new setting
where appropriate.
To make people's life easier the message shown by `show print elements'
now indicates if the setting also applies to character strings:
(gdb) set print characters elements
(gdb) show print elements
Limit on string chars or array elements to print is 200.
(gdb) set print characters unlimited
(gdb) show print elements
Limit on array elements to print is 200.
(gdb)
and the help text shows the dependency as well:
(gdb) help set print elements
Set limit on array elements to print.
"unlimited" causes there to be no limit.
This setting also applies to string chars when "print characters"
is set to "elements".
(gdb)
In the testsuite there are two minor updates, one to add `-characters'
to the list of completions now shown for the `print' command, and a bare
minimum pair of checks for the right handling of `set print characters'
and `show print characters', copied from the corresponding checks for
`set print elements' and `show print elements' respectively.
Co-Authored-By: Maciej W. Rozycki <macro@embecosm.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Rather than just `unlimited' allow the integer set commands (or command
options) to define arbitrary keywords for the user to use, removing
hardcoded arrangements for the `unlimited' keyword.
Remove the confusingly named `var_zinteger', `var_zuinteger' and
`var_zuinteger_unlimited' `set'/`show' command variable types redefining
them in terms of `var_uinteger', `var_integer' and `var_pinteger', which
have the range of [0;UINT_MAX], [INT_MIN;INT_MAX], and [0;INT_MAX] each.
Following existing practice `var_pinteger' allows extra negative values
to be used, however unlike `var_zuinteger_unlimited' any number of such
values can be defined rather than just `-1'.
The "p" in `var_pinteger' stands for "positive", for the lack of a more
appropriate unambiguous letter, even though 0 obviously is not positive;
"n" would be confusing as to whether it stands for "non-negative" or
"negative".
Add a new structure, `literal_def', the entries of which define extra
keywords allowed for a command and numerical values they correspond to.
Those values are not verified against the basic range supported by the
underlying variable type, allowing extra values to be allowed outside
that range, which may or may not be individually made visible to the
user. An optional value translation is possible with the structure to
follow the existing practice for some commands where user-entered 0 is
internally translated to UINT_MAX or INT_MAX. Such translation can now
be arbitrary. Literals defined by this structure are automatically used
for completion as necessary.
So for example:
const literal_def integer_unlimited_literals[] =
{
{ "unlimited", INT_MAX, 0 },
{ nullptr }
};
defines an extra `unlimited' keyword and a user-visible 0 value, both of
which get translated to INT_MAX for the setting to be used with.
Similarly:
const literal_def zuinteger_unlimited_literals[] =
{
{ "unlimited", -1, -1 },
{ nullptr }
};
defines the same keyword and a corresponding user-visible -1 value that
is used for the requested setting. If the last member were omitted (or
set to `{}') here, then only the keyword would be allowed for the user
to enter and while -1 would still be used internally trying to enter it
as a part of a command would result in an "integer -1 out of range"
error.
Use said error message in all cases (citing the invalid value requested)
replacing "only -1 is allowed to set as unlimited" previously used for
`var_zuinteger_unlimited' settings only rather than propagating it to
`var_pinteger' type. It could only be used for the specific case where
a single extra `unlimited' keyword was defined standing for -1 and the
use of numeric equivalents is discouraged anyway as it is for historical
reasons only that they expose GDB internals, confusingly different
across variable types. Similarly update the "must be >= -1" Guile error
message.
Redefine Guile and Python parameter types in terms of the new variable
types and interpret extra keywords as Scheme keywords and Python strings
used to communicate corresponding parameter values. Do not add a new
PARAM_INTEGER Guile parameter type, however do handle the `var_integer'
variable type now, permitting existing parameters defined by GDB proper,
such as `listsize', to be accessed from Scheme code.
With these changes in place it should be trivial for a Scheme or Python
programmer to expand the syntax of the `make-parameter' command and the
`gdb.Parameter' class initializer to have arbitrary extra literals along
with their internal representation supplied.
Update the testsuite accordingly.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
On openSUSE Leap 15.4 with python 3.6, the gdb.dap/basic-dap.exp test-case
fails as follows:
...
ERROR: eof reading json header
while executing
"error "eof reading json header""
invoked from within
"expect {
-i exp19 -timeout 10
-re "^Content-Length: (\[0-9\]+)\r\n" {
set length $expect_out(1,string)
exp_continue
}
-re "^(\[^\r\n\]+)..."
("uplevel" body line 1)
invoked from within
"uplevel $body" NONE eof reading json header
UNRESOLVED: gdb.dap/basic-dap.exp: startup - initialize
...
Investigation using a "catch throw" shows that:
...
(gdb)
at gdb/python/py-utils.c:396
396 error (_("Error occurred in Python: %s"), msg.get ());
(gdb) p msg.get ()
$1 = 0x2b91d10 "module 'queue' has no attribute 'SimpleQueue'"
...
The python class queue.SimpleQueue was introduced in python 3.7.
Fix this by falling back to queue.Queue for python <= 3.6.
Tested on x86_64-linux, by successfully running the test-case:
...
# of expected passes 47
...
The Debugger Adapter Protocol is a JSON-RPC protocol that IDEs can use
to communicate with debuggers. You can find more information here:
https://microsoft.github.io/debug-adapter-protocol/
Frequently this is implemented as a shim, but it seemed to me that GDB
could implement it directly, via the Python API. This patch is the
initial implementation.
DAP is implemented as a new "interp". This is slightly weird, because
it doesn't act like an ordinary interpreter -- for example it doesn't
implement a command syntax, and doesn't use GDB's ordinary event loop.
However, this seemed like the best approach overall.
To run GDB in this mode, use:
gdb -i=dap
The DAP code will accept JSON-RPC messages on stdin and print
responses to stdout. GDB redirects the inferior's stdout to a new
pipe so that output can be encapsulated by the protocol.
The Python code uses multiple threads to do its work. Separate
threads are used for reading JSON from the client and for writing JSON
to the client. All GDB work is done in the main thread. (The first
implementation used asyncio, but this had some limitations, and so I
rewrote it to use threads instead.)
This is not a complete implementation of the protocol, but it does
implement enough to demonstrate that the overall approach works.
There is a rudimentary test suite. It uses a JSON parser written in
pure Tcl. This parser is under the same license as Tcl itself, so I
felt it was acceptable to simply import it into the tree.
There is also a bit of documentation -- just documenting the new
interpreter name.
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
[ Partial resubmission of an earlier submission by Andrew (
https://sourceware.org/pipermail/gdb-patches/2012-September/096347.html ), so
listing him as co-author. ]
With x86_64-linux and target board unix/-m32, we have:
...
(gdb) continue^M
Continuing.^M
Exception #10^M
^M
Breakpoint 3, throw_exception_1 (e=10) at py-finish-breakpoint2.cc:23^M
23 throw new int (e);^M
(gdb) FAIL: gdb.python/py-finish-breakpoint2.exp: \
check FinishBreakpoint in catch()
...
The following scenario happens:
- set breakpoint in throw_exception_1, a function that throws an exception
- continue
- hit breakpoint, with call stack main.c:38 -> throw_exception_1
- set a finish breakpoint
- continue
- hit the breakpoint again, with call stack main.c:48 -> throw_exception
-> throw_exception_1
Due to the exception, the function call did not properly terminate, and the
finish breakpoint didn't trigger. This is expected behaviour.
However, the intention is that gdb detects this situation at the next stop
and calls the out_of_scope callback, which would result here in this test-case
in a rather confusing "exception did not finish" message. So the problem is
that this message doesn't show up, in other words, the out_of_scope callback
is not called.
[ Note that the fact that the situation is detected only at the next stop
(wherever that happens to be) could be improved upon, and the earlier
submission did that by setting a longjmp breakpoint. But I'm considering this
problem out-of-scope for this patch. ]
Note that the message does show up later, at thread exit:
...
[Inferior 1 (process 20046) exited with code 0236]^M
exception did not finish ...^M
...
The decision on whether to call the out_of_scope call back is taken in
bpfinishpy_detect_out_scope_cb, and the interesting bit is here:
...
if (b->pspace == current_inferior ()->pspace
&& (!target_has_registers ()
|| frame_find_by_id (b->frame_id) == NULL))
bpfinishpy_out_of_scope (finish_bp);
...
In the case of the thread exit, the callback triggers because
target_has_registers () == 0.
So why doesn't the callback trigger in the case of the breakpoint?
Well, the b->frame_id is the frame_id of the frame of main (the frame
in which the finish breakpoint is supposed to trigger), so AFAIU
frame_find_by_id (b->frame_id) == NULL will only be true once we've
left main, at which point I guess we don't stop till thread exit.
Fix this by saving the frame in which the finish breakpoint was created, and
using frame_find_by_id () == NULL on that frame instead, such that we have:
...
(gdb) continue^M
Continuing.^M
Exception #10^M
^M
Breakpoint 3, throw_exception_1 (e=10) at py-finish-breakpoint2.cc:23^M
23 throw new int (e);^M
exception did not finish ...^M
(gdb) FAIL: gdb.python/py-finish-breakpoint2.exp: \
check FinishBreakpoint in catch()
...
Still, the test-case is failing because it's setup to match the behaviour that
we get on x86_64-linux with target board unix/-m64:
...
(gdb) continue^M
Continuing.^M
Exception #10^M
stopped at ExceptionFinishBreakpoint^M
(gdb) PASS: gdb.python/py-finish-breakpoint2.exp: \
check FinishBreakpoint in catch()
...
So what happens here? Again, due to the exception, the function call did not
properly terminate, but the finish breakpoint still triggers. This is somewhat
unexpected. This happens because it just so happens to be that the frame
return address at which the breakpoint is set, is also the first instruction
after the exception has been handled. This is a know problem, filed as
PR29909, so KFAIL it, and modify the test-case to expect the out_of_scope
callback.
Also add a breakpoint after setting the finish breakpoint but before throwing
the exception, to check that we don't call the out_of_scope callback too early.
Tested on x86_64-linux, with target boards unix/-m32.
Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
PR python/27247
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27247
[I sent this earlier today, but I don't see it in the archives.
Resending it through a different computer / SMTP.]
The use of the static buffer in command_line_input is becoming
problematic, as explained here [1]. In short, with this patch [2] that
attempt to fix a post-hook bug, when running gdb.base/commands.exp, we
hit a case where we read a "define" command line from a script file
using command_command_line_input. The command line is stored in
command_line_input's static buffer. Inside the define command's
execution, we read the lines inside the define using command_line_input,
which overwrites the define command, in command_line_input's static
buffer. After the execution of the define command, execute_command does
a command look up to see if a post-hook is registered. For that, it
uses a now stale pointer that used to point to the define command, in
the static buffer, causing a use-after-free. Note that the pointer in
execute_command points to the dynamically-allocated buffer help by the
static buffer in command_line_input, not to the static object itself,
hence why we see a use-after-free.
Fix that by removing the static buffer. I initially changed
command_line_input and other related functions to return an std::string,
which is the obvious but naive solution. The thing is that some callees
don't need to return an allocated string, so this this an unnecessary
pessimization. I changed it to passing in a reference to an std::string
buffer, which the callee can use if it needs to return
dynamically-allocated content. It fills the buffer and returns a
pointers to the C string inside. The callees that don't need to return
dynamically-allocated content simply don't use it.
So, it started with modifying command_line_input as described above, all
the other changes derive directly from that.
One slightly shady thing is in handle_line_of_input, where we now pass a
pointer to an std::string's internal buffer to readline's history_value
function, which takes a `char *`. I'm pretty sure that this function
does not modify the input string, because I was able to change it (with
enough massaging) to take a `const char *`.
A subtle change is that we now clear a UI's line buffer using a
SCOPE_EXIT in command_line_handler, after executing the command.
This was previously done by this line in handle_line_of_input:
/* We have a complete command line now. Prepare for the next
command, but leave ownership of memory to the buffer . */
cmd_line_buffer->used_size = 0;
I think the new way is clearer.
[1] https://inbox.sourceware.org/gdb-patches/becb8438-81ef-8ad8-cc42-fcbfaea8cddd@simark.ca/
[2] https://inbox.sourceware.org/gdb-patches/20221213112241.621889-1-jan.vrany@labware.com/
Change-Id: I8fc89b1c69870c7fc7ad9c1705724bd493596300
Reviewed-By: Tom Tromey <tom@tromey.com>
In 2014, the function `gdbpy_should_stop' has been replaced with
`gdbpy_breakpoint_cond_says_stop'
This replaces `gdbpy_should_stop' with `gdbpy_breakpoint_cond_says_stop' in the
comments.
Since `gdbpy_should_stop' has been renamed as noted in `gdb/ChangeLog-2014':
* python/py-breakpoint.c (gdbpy_breakpoint_cond_says_stop): Renamed
from gdbpy_should_stop. Change result type to enum scr_bp_stop.
Change-Id: I0ef3491ce5e057c5e75ef8b569803b30a5838575
Approved-By: Simon Marchi <simon.marchi@efficios.com>
While working on another patch, Simon pointed out that GDB could be
improved by marking the functions passed to the disassembler as
noexcept.
https://sourceware.org/pipermail/gdb-patches/2022-October/193084.html
The reason this is important is the on some hosts, libopcodes, being C
code, will not be compiled with support for handling exceptions. As
such, an attempt to throw an exception over libopcodes code will cause
GDB to terminate.
See bug gdb/29712 for an example of when this happened.
In this commit all the functions that are passed to the disassembler,
and which might be used as callbacks by libopcodes are marked
noexcept.
Ideally, I would have liked to change these typedefs:
using read_memory_ftype = decltype (disassemble_info::read_memory_func);
using memory_error_ftype = decltype (disassemble_info::memory_error_func);
using print_address_ftype = decltype (disassemble_info::print_address_func);
using fprintf_ftype = decltype (disassemble_info::fprintf_func);
using fprintf_styled_ftype = decltype (disassemble_info::fprintf_styled_func);
which are declared in disasm.h, as including the noexcept keyword.
However, when I tried this, I ran into this warning/error:
In file included from ../../src/gdb/disasm.c:25:
../../src/gdb/disasm.h: In constructor ‘gdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*, gdb_disassemble_info::read_memory_ftype, gdb_disassemble_info::memory_error_ftype, gdb_disassemble_info::print_address_ftype)’:
../../src/gdb/disasm.h:116:3: error: mangled name for ‘gdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*, gdb_disassemble_info::read_memory_ftype, gdb_disassemble_info::memory_error_ftype, gdb_disassemble_info::print_address_ftype)’ will change in C++17 because the exception specification is part of a function type [-Werror=noexcept-type]
116 | gdb_printing_disassembler (struct gdbarch *gdbarch,
| ^~~~~~~~~~~~~~~~~~~~~~~~~
So I've left that change out. This does mean that if somebody adds a
new use of the disassembler classes in the future, and forgets to mark
the callbacks as noexcept, this will compile fine. We'll just have to
manually check for that during review.
