In an earlier patch, I wrote:
... It also adds some machinery so that attach stops can be
suppressed, which I think is the right thing to do.
However, after some discussions here at AdaCore, I now believe this to
be incorrect -- while DAP says that expected "continue" events should
be suppressed, there is no corresponding language for expected "stop"
events, and indeed "stop" events explicitly mention cases like "step".
This patch arranges for the stop event to be emitted again.
A user pointed out that gdb will print a Python exception when it gets
an EOF in DAP mode. And, it turns out that an EOF like this also
causes gdb not to exit. This is due to the refactoring that moved the
JSON reader to its own thread -- previously this caused an exception
to propagate and cause an exit, but now it just leaves the reader
hung.
This patch fixes these problems by arranging to handle EOF more
gracefully.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31217
This commit is the result of the following actions:
- Running gdb/copyright.py to update all of the copyright headers to
include 2024,
- Manually updating a few files the copyright.py script told me to
update, these files had copyright headers embedded within the
file,
- Regenerating gdbsupport/Makefile.in to refresh it's copyright
date,
- Using grep to find other files that still mentioned 2023. If
these files were updated last year from 2022 to 2023 then I've
updated them this year to 2024.
I'm sure I've probably missed some dates. Feel free to fix them up as
you spot them.
I noticed that the DAP attach test case (and similarly
remoted-dap.exp) had a rogue exception stack trace in the log. It
turns out that an attach will generate a stop that does not have a
reason.
This patch fixes the problem in the _on_stop event listener by making
it a bit more careful when examining the event reason. It also adds
some machinery so that attach stops can be suppressed, which I think
is the right thing to do.
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
This adds a new parameter to control the DAP logging level. By
default, "expected" exceptions are not logged, but the parameter lets
the user change this when more logging is desired.
This also changes a couple of spots to avoid logging the stack trace
for a DAPException.
This patch also documents the existing DAP logging parameter. I
forgot to document this before.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
This introduces a new DAPException class, and then changes various
spots in the DAP implementation to wrap "expected" exceptions in this.
This class will help detect rogue exceptions caused by bugs in the
implementation.
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
In many cases, it's not possible for gdb to discover the executable
when a DAP 'attach' request is used. This patch lets the IDE supply
this information.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
This implements DAP cancellation. A new object is introduced that
handles the details of cancellation. While cancellation is inherently
racy, this code attempts to make it so that gdb doesn't inadvertently
cancel the wrong request.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30472
Approved-By: Eli Zaretskii <eliz@gnu.org>
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
Cancellation will generally be seen by the DAP code as a
KeyboardInterrupt. However, this derives from BaseException and not
Exception, so a small change is needed to send_gdb_with_response, to
forward the exception to the DAP server thread.
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
This changes the DAP server to move the JSON reader to a new thread.
This is key to implementing request cancellation, as now requests can
be read while an earlier one is being serviced.
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
This patch introduces a new NotStoppedException type and changes the
DAP implementation of "not stopped" to use it. I was already touching
some code in this area and I thought this looked a little cleaner.
This also has the advantage that we can now choose not to log the
exception -- previously I was sometimes a bit alarmed when seeing this
in the logs, even though it is harmless.
Reviewed-By: Kévin Le Gouguec <legouguec@adacore.com>
Now that gdb adds stop-reason details to stop events, we can simplify
the DAP code to emit correct stop reasons in its own events. For the
most part a simple renaming of gdb reasons is sufficient; however,
"pause" must still be handled specially.
DAP specifies a "process" event that is sent when a process is started
or attached to. gdb was not emitting this (several DAP clients appear
to ignore it entirely), but it looked easy and harmless to implement.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30473
While working on cancellation, I noticed that a DAP 'pause' request
would set the "do not emit the continue" flag. This meant that a
subsequent request that should provoke a 'continue' event would
instead suppress the event.
I then tried writing a more obvious test case for this, involving an
inferior call -- and discovered that gdb.events.cont does not fire for
an inferior call.
This patch installs a new event listener for gdb.events.inferior_call
and arranges for this to emit continue and stop events when
appropriate. It also fixes the original bug, by adding a check to
exec_and_expect_stop.
I ran into a failure in test-case gdb.python/py-missing-debug.exp with python
3.6, which was fixed by commit 7db795bc67 ("gdb/python: remove use of
str.isascii()").
However, I subsequently ran into a failure with python 3.11:
...
(gdb) PASS: $exp: initial checks: debug info no longer found
source py-missing-debug.py^M
Traceback (most recent call last):^M
File "py-missing-debug.py", line 17, in <module>^M
from gdb.missing_debug import MissingDebugHandler^M
File "missing_debug.py", line 21, in <module>^M
from curses.ascii import isascii, isalnum^M
File "/usr/lib64/python3.11/_import_failed/curses.py", line 16, in <module>^M
raise ImportError(f"""Module '{failed_name}' is not installed.^M
ImportError: Module 'curses' is not installed.^M
Use:^M
sudo zypper install python311-curses^M
to install it.^M
(gdb) FAIL: $exp: source python script
...
Apparently I have the curses module installed for 3.6, but not 3.11.
I could just install it, but the test-case worked fine with 3.11 before commit
7db795bc67.
Fix this by only using the curses module when necessary, for python <= 3.7.
Tested on x86_64-linux, with both python 3.6 and 3.11.
A couple of spots in the DAP code use the same workaround for the
absence of queue.SimpleQueue before Python 3.6. This patch
consolidates these into a single spot.
DAP specifies that a request can fail with the "notStopped" message if
the inferior is running but the request requires that it first be
stopped.
This patch implements this for gdb. Most requests are assumed to
require a stopped inferior, and the exceptions are noted by a new
'request' parameter.
You may notice that the implementation is a bit racy. I think this is
inherent -- unless the client waits for a stop event before sending a
request, the request may be processed at any time relative to a stop.
https://sourceware.org/bugzilla/show_bug.cgi?id=31037
Reviewed-by: Kévin Le Gouguec <legouguec@adacore.com>
ExecutionInvoker is no longer really needed, due to the previous DAP
refactoring. This patch removes it in favor of an ordinary function.
One spot (the 'continue' request) could still have used it, but is
more succinctly expressed as a lambda.
Reviewed-by: Kévin Le Gouguec <legouguec@adacore.com>
Nearly every DAP request implementation forwards its work to the gdb
thread, using send_gdb_with_response. This patch refactors the
'request' decorator to make this automatic, and to provide some
parameters so that the unusual requests can express their needs as
well.
In a few spots this simplifies the code by removing an unnecessary
helper function. This could be done in more places as well if we
wanted.
The main motivation for this patch is that I thought it would be
helpful for cancellation. I am still working on that, but meanwhile
the parameterization of 'request' makes it easy to handle the
'notStopped' response as well.
Reviewed-by: Kévin Le Gouguec <legouguec@adacore.com>
DAP specifies a StackFrameFormat object that can be used to change how
the "name" part of a stack frame is constructed. While this output
can already be done in a nicer way (and also letting the client choose
the formatting), nevertheless it is in the spec, so I figured I'd
implement it.
While implementing this, I discovered that the current code does not
correctly preserve frame IDs across requests. I rewrote frame
iteration to preserve this, and it turned out to be simpler to combine
these patches.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30475
This commit:
commit 8f6c452b5a
Date: Sun Oct 15 22:48:42 2023 +0100
gdb: implement missing debug handler hook for Python
introduced a use of str.isascii(), which was only added in Python 3.7.
This commit switches to use curses.ascii.isascii(), as this was
available in 3.6.
The same is true for str.isalnum(), which is replaced with
curses.ascii.isalnum().
There should be no user visible changes after this commit.
A co-worker requested that the DAP scope for a nested function's frame
also show the variables from outer frames. DAP doesn't directly
support this notion, so this patch arranges to put these variables
into the inner frames "Locals" scope.
I chose to do this only for DAP. For CLI and MI, gdb currently does
not do this, so this preserves the behavior.
Note that an earlier patch (see commit 4a1311ba) removed some code
that seemed to do something similar. However, that code did not
actually work.
While working on static links, I noticed that the DAP scopes code does
not handle the scenario where a frame decorator returns None. This
situation should be handled identically to a frame decorator returning
an empty iterator.
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 patch implements the DAP setVariable request.
setVariable is a bit odd in that it specifies the variable to modify
by passing in the variable's container and the name of the variable.
This approach can't handle variable shadowing (there are a couple of
open DAP bugs on this topic), so this patch renames duplicates to
avoid the problem.
A pretty-printer's 'children' method may return values other than a
gdb.Value -- it may return any value that can be converted to a
gdb.Value.
I noticed that this case did not work for DAP. This patch fixes the
problem.
Andry pointed out that the DAP code did not properly handle
gdb.LazyString results from a pretty-printer, yielding:
TypeError: Object of type LazyString is not JSON serializable
This patch fixes the problem, partly with a small patch in varref.py,
but mainly by implementing tp_str for LazyString.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Andry Ogorodnik, a co-worker, noticed that multiple "scopes" requests
with the same frame would yield different variableReference values in
the response.
This patch adds a regression test for this, and adds a scope cache in
scopes.py, ensuring that multiple identical requests will get the same
response.
Tested-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>
printing.py references "gdb.printing" in a few spots, but there's no
need for this. I think this is leftover from when this code was
(briefly) in some other module. This patch removes the unnecessary
qualifications. Tested on x86-64 Fedora 36.
This adds two new pretty-printer methods, to support random access to
children. The methods are implemented for the no-op array printer,
and DAP is updated to use this.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
There was an earlier thread about adding new methods to
pretty-printers:
https://sourceware.org/pipermail/gdb-patches/2023-June/200503.html
We've known about the need for printer extensibility for a while, but
have been hampered by backward-compatibilty concerns: gdb never
documented that printers might acquire new methods, and so existing
printers may have attribute name clashes.
To solve this problem, this patch adds a new pretty-printer tag class
that signals to gdb that the printer follows new extensibility rules.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30816
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
With any gdb.dap test and python 3.6 I run into:
...
Error occurred in Python: 'code' object has no attribute 'co_posonlyargcount'
ERROR: eof reading json header
...
The attribute is not supported before python 3.8, which introduced the
"Positional−only Parameters" concept.
Fix this by using try/except AttributeError.
Tested on x86_64-linux:
- openSUSE Leap 15.4 with python 3.6, and
- openSUSE Tumbleweed with python 3.11.5.
Approved-By: Tom Tromey <tom@tromey.com>
The buildbot pointed out that the last DAP series I checked in had an
issue. Looking into it, it seems there is a stray trailing "," in
breakpoint.py. This patch removes it.
This seems to point out a test suite deficiency. I will look into
fixing that.
According to the DAP specification if the "sourceReference" field is
included in a Source object, then the DAP client _must_ make a "source"
request to the debugger to retrieve file contents, even if the Source
object also includes path information.
If the Source's path field is a valid path that the DAP client is able
to read from the filesystem, having to make another request to the
debugger to get the file contents is wasteful and leads to incorrect
results (DAP clients will try to get the contents from the server and
display those contents as a file with the name in "source.path", but
this will conflict with the _acutal_ existing file at "source.path").
Instead, only set "sourceReference" if the source file path does not
exist.
Approved-By: Tom Tromey <tom@tromey.com>
If the breakpoint has a fullname, use that as the source path when
resolving the breakpoint source information. This is consistent with
other callers of make_source which also use "fullname" if it exists (see
e.g. DAPFrameDecorator which returns the symtab's fullname).
Approved-By: Tom Tromey <tom@tromey.com>
Some DAP clients may send additional parameters in the stepOut command
(e.g. "granularity") which are not used by GDB, but should nonetheless
be accepted without error.
Approved-By: Tom Tromey <tom@tromey.com>
Not all breakpoints have a source location. For example, a breakpoint
set on a raw address will have only the "address" field populated, but
"source" will be None, which leads to a RuntimeError when attempting to
unpack the filename and line number.
Before attempting to unpack the filename and line number from the
breakpoint, ensure that the source information is not None. Also
populate the source and line information separately from the
"instructionReference" field, so that breakpoints that include only an
address are still included.
Approved-By: Tom Tromey <tom@tromey.com>
A user pointed out that the current DAP variable code does not let the
client deference a pointer. Oops!
Fixing this oversight is simple enough -- adding a new no-op
pretty-printer for pointers and references is quite simple.
However, doing this naive caused a regession in scopes.exp, which
expected there to be no children of a 'const char *' variable. This
problem was fixed by the preceding patches in the series, which ensure
that a C type of this kind is recognized as a string.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30821
A user pointed out that if a DAP setBreakpoints request has a 'source'
field in a SourceBreakpoint object, then the gdb DAP implementation
will throw an exception.
While SourceBreakpoint does not allow 'source' in the spec, it seems
better to me to accept it. I don't think we should fully go down the
"Postel's Law" path -- after all, we have the type-checker -- but at
the same time, if we do send errors, they should be intentional and
not artifacts of the implementation.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30820
This changes the no-op pretty printers -- used by DAP -- to handle
array- and string-like objects known by the gdb core. Two new tests
are added, one for Ada and one for Rust.
Right now, if a program uses multiple languages, DAP value formatting
will always use the language of the innermost frame. However, it is
better to use the variable's defining frame instead. This patch does
this by selecting the frame first.
This also fixes a possibly latent bug in the "stepOut" command --
"finish" is sensitive to the selected frame, but the DAP code may
already select other frames when convenient. The DAP stepOut request
only works on the newest frame, so be sure to select it before
invoking "finish".
DAP specifies an event that should be sent when a module is removed.
This patch implements this.
Tested-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>
A co-worker pointed out that gdb's DAP implementation might return an
integer for the name of a stack frame, like:
{"id": 1, "name": 93824992310799, ...}
This can be seen currently in the logs of the bt-nodebug.exp test
case.
What is happening is that FrameDecorator falls back on returning the
PC when the frame's function symbol cannot be found, relying on the
gdb core to look up the minsym and print its name.
This can actually yield the wrong answer sometimes, because it falls
into the get_frame_pc / get_frame_address_in_block problem -- if the
frame is at a call to a noreturn function, the PC in this case might
appear to be in the next function in memory. For more on this, see:
https://sourceware.org/bugzilla/show_bug.cgi?id=8416
and related bugs.
However, there's a different approach we can take: the code here can
simply use Frame.name. This handles the PC problem correctly, and
gets us the information we need.
This implements the DAP "source" request. I renamed the
"loadedSources" function from "sources" to "loaded_sources" to avoid
any confusion. I also moved the loadedSources test to the new
sources.exp.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30691
