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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.
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This commit makes the gdb.Command.complete methods more verbose when
it comes to error handling.
Previous to this commit if any commands implemented in Python
implemented the complete method, and if there were any errors
encountered when calling that complete method, then GDB would silently
hide the error and continue as if there were no completions.
This makes is difficult to debug any errors encountered when writing
completion methods, and encourages the idea that Python extensions can
be broken, and GDB will just silently work around them.
I don't think this is a good idea. GDB should encourage extensions to
be written correctly, and robustly, and one way in which GDB can (I
think) support this, is by pointing out when an extension goes wrong.
In this commit I've gone through the Python command completion code,
and added calls to gdbpy_print_stack() or gdbpy_print_stack_or_quit()
in places where we were either clearing the Python error, or, in some
cases, just not handling the error at all.
One thing I have not changed is in cmdpy_completer (py-cmd.c) where we
process the list of completions returned from the Command.complete
method; this routine includes a call to gdbpy_is_string to check a
possible completion is a string, if not the completion is ignored.
I was tempted to remove this check, attempt to complete each result to
a string, and display an error if the conversion fails. After all,
returning anything but a string is surely a mistake by the extension
author.
However, the docs clearly say that only strings within the returned
list will be considered as completions. Anything else is ignored. As
such, and to avoid (what I think is pretty unlikely) breakage of
existing code, I've retained the gdbpy_is_string check.
After the gdbpy_is_string check we call python_string_to_host_string,
if this call fails then I do now print the error, where before we
ignored the error. I think this is OK; if GDB thinks something is a
string, but still can't convert it to a string, then I think it's OK
to display the error in that case.
Another case which I was a little unsure about was in
cmdpy_completer_helper, and the call to PyObject_CallMethodObjArgs,
which is when we actually call Command.complete. Previously, if this
call resulted in an exception then we would ignore this and just
pretend there were no completions.
Of all the changes, this is possibly the one with the biggest
potential for breaking existing scripts, but also, is, I think, the
most useful change. If the user code is wrong in some way, such that
an exception is raised, then previously the user would have no obvious
feedback about this breakage. Now GDB will print the exception for
them, making it, I think, much easier to debug their extension. But,
if there is user code in the wild that relies on raising an exception
as a means to indicate there are no completions .... well, that code
is going to break after this commit. I think we can live with this
though, the exceptions means no completions thing was never documented
behaviour.
I also added a new error() call if the PyObject_CallMethodObjArgs call
raises an exception. This causes the completion mechanism within GDB
to stop. Within GDB the completion code is called twice, the first
time to compute the work break characters, and then a second time to
compute the actual completions.
If PyObject_CallMethodObjArgs raises an exception when computing the
word break character, and we print it by calling
gdbpy_print_stack_or_quit(), but then carry on as if
PyObject_CallMethodObjArgs had returns no completions, GDB will
call the Python completion code again, which results in another call
to PyObject_CallMethodObjArgs, which might raise the same exception
again. This results in the Python exception being printed twice.
By throwing a C++ exception after the failed
PyObject_CallMethodObjArgs call, the completion mechanism is aborted,
and no completions are offered. But importantly, the Python exception
is only printed once. I think this gives a much better user
experience.
I've added some tests to cover this case, as I think this is the most
likely case that a user will run into.
Approved-By: Tom Tromey <tom@tromey.com>
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GDB's Python API documentation for gdb.Command.complete() says:
The 'complete' method can return several values:
* If the return value is a sequence, the contents of the
sequence are used as the completions. It is up to 'complete'
to ensure that the contents actually do complete the word. A
zero-length sequence is allowed, it means that there were no
completions available. Only string elements of the sequence
are used; other elements in the sequence are ignored.
* If the return value is one of the 'COMPLETE_' constants
defined below, then the corresponding GDB-internal completion
function is invoked, and its result is used.
* All other results are treated as though there were no
available completions.
So, returning a non-sequence, and non-integer from a complete method
should be fine; it should just be treated as though there are no
completions.
However, if I write a complete method that returns None, I see this
behaviour:
(gdb) complete completefilenone x
Python Exception <class 'TypeError'>: 'NoneType' object is not iterable
warning: internal error: Unhandled Python exception
(gdb)
Which is caused because we currently assume that anything that is not
an integer must be iterable, and we call PyObject_GetIter on it. When
this call fails a Python exception is set, but instead of
clearing (and therefore ignoring) this exception as we do everywhere
else in the Python completion code, we instead just return with the
exception set.
In this commit I add a PySequence_Check call. If this call returns
false (and we've already checked the integer case) then we can assume
there are no completion results.
I've added a test which checks returning a non-sequence.
Approved-By: Tom Tromey <tom@tromey.com>
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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.
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This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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Re-format all Python files using black [1] version 21.4b0. The goal is
that from now on, we keep all Python files formatted using black. And
that we never have to discuss formatting during review (for these files
at least) ever again.
One change is needed in gdb.python/py-prettyprint.exp, because it
matches the string representation of an exception, which shows source
code. So the change in formatting must be replicated in the expected
regexp.
To document our usage of black I plan on adding this to the "GDB Python
Coding Standards" wiki page [2]:
--8<--
All Python source files under the `gdb/` directory must be formatted
using black version 21.4b0.
This specific version can be installed using:
$ pip3 install 'black == 21.4b0'
All you need to do to re-format files is run `black <file/directory>`,
and black will re-format any Python file it finds in there. It runs
quite fast, so the simplest is to do:
$ black gdb/
from the top-level.
If you notice that black produces changes unrelated to your patch, it's
probably because someone forgot to run it before you. In this case,
don't include unrelated hunks in your patch. Push an obvious patch
fixing the formatting and rebase your work on top of that.
-->8--
Once this is merged, I plan on setting a up an `ignoreRevsFile`
config so that git-blame ignores this commit, as described here:
https://github.com/psf/black#migrating-your-code-style-without-ruining-git-blame
I also plan on working on a git commit hook (checked in the repo) to
automatically check the formatting of the Python files on commit.
[1] https://pypi.org/project/black/
[2] https://sourceware.org/gdb/wiki/Internals%20GDB-Python-Coding-Standards
gdb/ChangeLog:
* Re-format all Python files using black.
gdb/testsuite/ChangeLog:
* Re-format all Python files using black.
* gdb.python/py-prettyprint.exp (run_lang_tests): Adjust.
Change-Id: I28588a22c2406afd6bc2703774ddfff47cd61919
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This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
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gdb/ChangeLog:
Update copyright year range in all GDB files.
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This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update copyright year range in all GDB files
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This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update year range in copyright notice of all files.
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This patch is related to PR python/16699, and is an improvement over the
patch posted here:
<https://sourceware.org/ml/gdb-patches/2014-03/msg00301.html>
Keith noticed that, when using the "complete" command on GDB to complete
a Python command, some strange things could happen. In order to
understand what can go wrong, I need to explain how the Python
completion mechanism works.
When the user requests a completion of a Python command by using TAB,
GDB will first try to determine the right set of "brkchars" that will be
used when doing the completion. This is done by actually calling the
"complete" method of the Python class. Then, when we already know the
"brkchars" that will be used, we call the "complete" method again, for
the same values.
If you read the thread mentioned above, you will see that one of the
design decisions was to make the "cmdpy_completer_helper" (which is the
function the does the actual calling of the "complete" method) cache the
first result of the completion, since this result will be used in the
second call, to do the actual completion.
The problem is that the "complete" command does not process the
brkchars, and the current Python completion mechanism (improved by the
patch mentioned above) relies on GDB trying to determine the brkchars,
and then doing the completion itself. Therefore, when we use the
"complete" command instead of doing a TAB-completion on GDB, there is a
scenario where we can use the invalid cache of a previous Python command
that was completed before. For example:
(gdb) A <TAB>
(gdb) complete B
B value1
B value10
B value2
B value3
B value4
B value5
B value6
B value7
B value8
B value9
(gdb) B <TAB>
comp1 comp2 comp4 comp6 comp8
comp10 comp3 comp5 comp7 comp9
Here, we see that "complete B " gave a different result than "B <TAB>".
The reason for that is because "A <TAB>" was called before, and its
completion results were "value*", so when GDB tried to "complete B " it
wrongly answered with the results for A. The problem here is using a
wrong cache (A's cache) for completing B.
We tried to come up with a solution that would preserve the caching
mechanism, but it wasn't really possible. So I decided to completely
remove the cache, and doing the method calling twice for every
completion. This is not optimal, but I do not think it will impact
users noticeably.
It is worth mentioning another small issue that I found. The code was
doing:
wordobj = PyUnicode_Decode (word, sizeof (word), host_charset (), NULL);
which is totally wrong, because using "sizeof" here will lead to always
the same result. So I changed this to use "strlen". The testcase also
catches this problem.
Keith kindly expanded the existing testcase to cover the problem
described above, and everything is passing.
gdb/ChangeLog:
2015-04-08 Sergio Durigan Junior <sergiodj@redhat.com>
PR python/16699
* python/py-cmd.c (cmdpy_completer_helper): Adjust function to not
use a caching mechanism. Adjust comments and code to reflect
that. Replace 'sizeof' by 'strlen' when fetching 'wordobj'.
(cmdpy_completer_handle_brkchars): Adjust call to
cmdpy_completer_helper. Call Py_XDECREF for 'resultobj'.
(cmdpy_completer): Likewise.
gdb/testsuite/ChangeLog:
2015-04-08 Keith Seitz <keiths@redhat.com>
PR python/16699
* gdb.python/py-completion.exp: New tests for completion.
* gdb.python/py-completion.py (CompleteLimit1): New class.
(CompleteLimit2): Likewise.
(CompleteLimit3): Likewise.
(CompleteLimit4): Likewise.
(CompleteLimit5): Likewise.
(CompleteLimit6): Likewise.
(CompleteLimit7): Likewise.
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gdb/ChangeLog:
Update year range in copyright notice of all files.
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completer class
This PR came from a Red Hat bug that was filed recently. I checked and
it still exists on HEAD, so here's a proposed fix. Although this is
marked as a Python backend bug, this is really about the completion
mechanism used by GDB. Since this code reminds me of my first attempt
to make a good noodle, it took me quite some time to fix it in a
non-intrusive way.
The problem is triggered when one registers a completion method inside a
class in a Python script, rather than registering the command using a
completer class directly. For example, consider the following script:
class MyFirstCommand(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'myfirstcommand',gdb.COMMAND_USER,gdb.COMPLETE_FILENAME)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
class MySecondCommand(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'mysecondcommand',gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return gdb.COMPLETE_FILENAME
MyFirstCommand ()
MySecondCommand ()
When one loads this into GDB and tries to complete filenames for both
myfirstcommand and mysecondcommand, she gets:
(gdb) myfirstcommand /hom<TAB>
(gdb) myfirstcommand /home/
^
...
(gdb) mysecondcommand /hom<TAB>
(gdb) mysecondcommand /home
^
(The "^" marks the final position of the cursor after the TAB).
So we see that myfirstcommand honors the COMPLETE_FILENAME class (as
specified in the command creation), but mysecondcommand does not. After
some investigation, I found that the problem lies with the set of word
break characters that is used for each case. The set should be the same
for both commands, but it is not.
During the process of deciding which type of completion should be used,
the code in gdb/completer.c:complete_line_internal analyses the command
that requested the completion and tries to determine the type of
completion wanted by checking which completion function will be called
(e.g., filename_completer for filenames, location_completer for
locations, etc.).
This all works fine for myfirstcommand, because immediately after the
command registration the Python backend already sets its completion
function to filename_completer (which then causes the
complete_line_internal function to choose the right set of word break
chars). However, for mysecondcommand, this decision is postponed to
when the completer function is evaluated, and the Python backend uses an
internal completer (called cmdpy_completer). complete_line_internal
doesn't know about this internal completer, and can't choose the right
set of word break chars in time, which then leads to a bad decision when
completing the "/hom" word.
So, after a few attempts, I decided to create another callback in
"struct cmd_list_element" that will be responsible for handling the case
when there is an unknown completer function for complete_line_internal
to work with. So far, only the Python backend uses this callback, and
only when the user provides a completer method instead of registering
the command directly with a completer class. I think this is the best
option because it not very intrusive (all the other commands will still
work normally), but especially because the whole completion code is so
messy that it would be hard to fix this without having to redesign
things.
I have regtested this on Fedora 18 x86_64, without regressions. I also
included a testcase.
gdb/ChangeLog:
2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com>
PR python/16699
* cli/cli-decode.c (set_cmd_completer_handle_brkchars): New
function.
(add_cmd): Set "completer_handle_brkchars" to NULL.
* cli/cli-decode.h (struct cmd_list_element)
<completer_handle_brkchars>: New field.
* command.h (completer_ftype_void): New typedef.
(set_cmd_completer_handle_brkchars): New prototype.
* completer.c (set_gdb_completion_word_break_characters): New
function.
(complete_line_internal): Call "completer_handle_brkchars"
callback from command.
* completer.h: Include "command.h".
(set_gdb_completion_word_break_characters): New prototype.
* python/py-cmd.c (cmdpy_completer_helper): New function.
(cmdpy_completer_handle_brkchars): New function.
(cmdpy_completer): Adjust to use cmdpy_completer_helper.
(cmdpy_init): Set completer_handle_brkchars to
cmdpy_completer_handle_brkchars.
gdb/testsuite/ChangeLog:
2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com>
PR python/16699
* gdb.python/py-completion.exp: New file.
* gdb.python/py-completion.py: Likewise.
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