This adds a 'summary' mode to Value.format_string and to
gdb.print_options. For the former, it lets Python code format values
using this mode. For the latter, it lets a printer potentially detect
if it is being called in a backtrace with 'set print frame-arguments'
set to 'scalars'.
I considered adding a new mode here to let a pretty-printer see
whether it was being called in a 'backtrace' context at all, but I'm
not sure if this is really desirable.
PR python/17291 asks for access to the current print options. While I
think this need is largely satisfied by the existence of
Value.format_string, it seemed to me that a bit more could be done.
First, while Value.format_string uses the user's settings, it does not
react to temporary settings such as "print/x". This patch changes
this.
Second, there is no good way to examine the current settings (in
particular the temporary ones in effect for just a single "print").
This patch adds this as well.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17291
PR python/27000 points out that gdb.block_for_pc will accept a Python
integer, but not a gdb.Value. This patch corrects this oversight.
I looked at all uses of GDB_PY_LLU_ARG and fixed these up to use
get_addr_from_python instead. I also looked at uses of GDB_PY_LL_ARG,
but those seemed relatively unlikely to be useful with a gdb.Value, so
I didn't change them. My thinking here is that a Value will typically
come from inferior memory, and something like a line number is not too
likely to be found this way.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27000
PR python/29217 points out that gdb.parameter will return bool values,
but gdb.set_parameter will not properly accept them. This patch fixes
the problem by adding a special case to set_parameter.
I looked at a fix involving rewriting set_parameter in C++. However,
this one is simpler.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29217
Sometimes an objfile comes from memory and not from a file. It can be
useful to be able to check this from Python, so this patch adds a new
"is_file" attribute.
Pierre-Marie noticed that, while gdb.events is a Python module, it
can't be imported. This patch changes how this module is created, so
that it can be imported, while also ensuring that the module is always
visible, just as it was in the past.
This new approach required one non-obvious change -- when running
gdb.base/warning.exp, where --data-directory is intentionally not
found, the event registries can now be nullptr. Consequently, this
patch probably also requires
https://sourceware.org/pipermail/gdb-patches/2022-June/189796.html
Note that this patch obsoletes
https://sourceware.org/pipermail/gdb-patches/2022-June/189797.html
I noticed a few spots that were explicitly creating new references to
Py_True or Py_False. It's simpler here to use PyBool_FromLong, so
this patch changes all the places I found.
This patch makes it possible to allow Value.format_string() to return
nibbles output.
When we set the parameter of nibbles to True, we can achieve the
displaying binary values in groups of every four bits.
Here's an example:
(gdb) py print (gdb.Value (1230).format_string (format='t', nibbles=True))
0100 1100 1110
(gdb)
Note that the parameter nibbles is only useful if format='t' is also used.
This patch also includes update to the relevant testcase and
documentation.
Tested on x86_64 openSUSE Tumbleweed.
This converts location_spec_to_string to a method of location_spec,
simplifying the code using it, as it no longer has to use
std::unique_ptr::get().
Change-Id: I621bdad8ea084470a2724163f614578caf8f2dd5
Currently, there's the location_spec hierarchy, and then some
location_spec subclasses have their own struct type holding all their
data fields.
I.e., there is this:
location_spec
explicit_location_spec
linespec_location_spec
address_location_spec
probe_location_spec
and then these separate types:
explicit_location
linespec_location
where:
explicit_location_spec
has-a explicit_location
linespec_location_spec
has-a linespec_location
This patch eliminates explicit_location and linespec_location,
inlining their members in the corresponding location_spec type.
The location_spec subclasses were the ones currently defined in
location.c, so they are moved to the header. Since the definitions of
the classes are now visible, we no longer need location_spec_deleter.
Some constructors that are used for cloning location_specs, like:
explicit explicit_location_spec (const struct explicit_location *loc)
... were converted to proper copy ctors.
In the process, initialize_explicit_location is eliminated, and some
functions that returned the "data type behind a locspec", like
get_linespec_location are converted to downcast functions, like
as_linespec_location_spec.
Change-Id: Ia31ccef9382b25a52b00fa878c8df9b8cf2a6c5a
Currently, GDB internally uses the term "location" for both the
location specification the user input (linespec, explicit location, or
an address location), and for actual resolved locations, like the
breakpoint locations, or the result of decoding a location spec to
SaLs. This is expecially confusing in the breakpoints module, as
struct breakpoint has these two fields:
breakpoint::location;
breakpoint::loc;
"location" is the location spec, and "loc" is the resolved locations.
And then, we have a method called "locations()", which returns the
resolved locations as range...
The location spec type is presently called event_location:
/* Location we used to set the breakpoint. */
event_location_up location;
and it is described like this:
/* The base class for all an event locations used to set a stop event
in the inferior. */
struct event_location
{
and even that is incorrect... Location specs are used for finding
actual locations in the program in scenarios that have nothing to do
with stop events. E.g., "list" works with location specs.
To clean all this confusion up, this patch renames "event_location" to
"location_spec" throughout, and then all the variables that hold a
location spec, they are renamed to include "spec" in their name, like
e.g., "location" -> "locspec". Similarly, functions that work with
location specs, and currently have just "location" in their name are
renamed to include "spec" in their name too.
Change-Id: I5814124798aa2b2003e79496e78f95c74e5eddca
I noticed that emit_exiting_event does not check whether there are any
listeners before creating the event object. All other event emitters
do this, so this patch updates this one as well.
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
This commit is setup for the next commit.
In the next commit I will add a Python API to intercept the print_insn
calls within GDB, each print_insn call is responsible for
disassembling, and printing one instruction. After the next commit it
will be possible for a user to write Python code that either wraps
around the existing disassembler, or even, in extreme situations,
entirely replaces the existing disassembler.
This commit does not add any new Python API.
What this commit does is put the extension language framework in place
for a print_insn hook. There's a new callback added to 'struct
extension_language_ops', which is then filled in with nullptr for Python
and Guile.
Finally, in the disassembler, the code is restructured so that the new
extension language function ext_lang_print_insn is called before we
delegate to gdbarch_print_insn.
After this, the next commit can focus entirely on providing a Python
implementation of the new print_insn callback.
There should be no user visible change after this commit.
Convert the gdbpy_err_fetch class to make use of gdbpy_ref, this
removes the need for manual reference count management, and allows the
destructor to be removed.
There should be no functional change after this commit.
I think this cleanup is worth doing on its own, however, in a later
commit I will want to copy instances of gdbpy_err_fetch, and switching
to using gdbpy_ref means that I can rely on the default copy
constructor, without having to add one that handles the reference
counts, so this is good preparation for that upcoming change.
I noticed that solib_name_from_address returned a non-const string,
but it's more appropriate to return const. This patch implements
this. Tested by rebuilding.
I found a comment that referred to Python 2, but that is now obsolete
-- the code it refers to is gone. I'm checking in this patch to
remove the comment.
There's a similar comment elsewhere, but I plan to remove that one in
another patch I'm going to submit shortly.
This adds the gdb.current_language function, which can be used to find
the current language without (1) ever having the value "auto" or (2)
having to parse the output of "show language".
It also adds the gdb.Frame.language, which can be used to find the
language of a given frame. This is normally preferable if one has a
Frame object handy.
Consider this command defined in Python (in the file test-cmd.py):
class test_cmd (gdb.Command):
"""
This is the first line.
Indented second line.
This is the third line.
"""
def __init__ (self):
super ().__init__ ("test-cmd", gdb.COMMAND_OBSCURE)
def invoke (self, arg, from_tty):
print ("In test-cmd")
test_cmd()
Now, within a GDB session:
(gdb) source test-cmd.py
(gdb) help test-cmd
This is the first line.
Indented second line.
This is the third line.
(gdb)
I think there's three things wrong here:
1. The leading blank line,
2. The trailing blank line, and
3. Every line is indented from the left edge slightly.
The problem of course, is that GDB is using the Python doc string
verbatim as its help text. While the user has formatted the help text
so that it appears clear within the .py file, this means that the text
appear less well formatted when displayed in the "help" output.
The same problem can be observed for gdb.Parameter objects in their
set/show output.
In this commit I aim to improve the "help" output for commands and
parameters.
To do this I have added gdbpy_fix_doc_string_indentation, a new
function that rewrites the doc string text following the following
rules:
1. Leading blank lines are removed,
2. Trailing blank lines are removed, and
3. Leading whitespace is removed in a "smart" way such that the
relative indentation of lines is retained.
With this commit in place the above example now looks like this:
(gdb) source ~/tmp/test-cmd.py
(gdb) help test-cmd
This is the first line.
Indented second line.
This is the third line.
(gdb)
Which I think is much neater. Notice that the indentation of the
second line is retained. Any blank lines within the help text (not
leading or trailing) will be retained.
I've added a NEWS entry to note that there has been a change in
behaviour, but I didn't update the manual. The existing manual is
suitably vague about how the doc string is used, so I think the new
behaviour is covered just as well by the existing text.
Make use of gdb::unique_xmalloc_ptr<char> to hold the documentation
string in cmdpy_init (when creating a custom GDB command in Python).
I think this is all pretty straight forward, the only slight weirdness
is the removal of the call to free toward the end of this function.
Prior to this commit, if an exception was thrown after the GDB command
was created then we would (I think) end up freeing the documentation
string even though the command would remain registered with GDB, which
would surely lead to undefined behaviour.
After this commit we release the doc string at the point that we hand
it over to the command creation routines. If we throw _after_ the
command has been created within GDB then the doc string will be left
live. If we throw during the command creation itself (either from
add_prefix_cmd or add_cmd) then it is up to those functions to free
the doc string (I suspect we don't, but I think in general the
commands are pretty bad at cleaning up after themselves, so I don't
think this is a huge problem).
Even after the previous patches reworking the inheritance of several
breakpoint types, the present breakpoint hierarchy looks a bit
surprising, as we have "breakpoint" as the superclass, and then
"base_breakpoint" inherits from "breakpoint". Like so, simplified:
breakpoint
base_breakpoint
ordinary_breakpoint
internal_breakpoint
momentary_breakpoint
ada_catchpoint
exception_catchpoint
tracepoint
watchpoint
catchpoint
exec_catchpoint
...
The surprising part to me is having "base_breakpoint" being a subclass
of "breakpoint". I'm just refering to naming here -- I mean, you'd
expect that it would be the top level baseclass that would be called
"base".
Just flipping the names of breakpoint and base_breakpoint around
wouldn't be super great for us, IMO, given we think of every type of
*point as a breakpoint at the user visible level. E.g., "info
breakpoints" shows watchpoints, tracepoints, etc. So it makes to call
the top level class breakpoint.
Instead, I propose renaming base_breakpoint to code_breakpoint. The
previous patches made sure that all code breakpoints inherit from
base_breakpoint, so it's fitting. Also, "code breakpoint" contrasts
nicely with a watchpoint also being typically known as a "data
breakpoint".
After this commit, the resulting hierarchy looks like:
breakpoint
code_breakpoint
ordinary_breakpoint
internal_breakpoint
momentary_breakpoint
ada_catchpoint
exception_catchpoint
tracepoint
watchpoint
catchpoint
exec_catchpoint
...
... which makes a lot more sense to me.
I've left this patch as last in the series in case people want to
bikeshed on the naming.
"code" has a nice property that it's exactly as many letters as
"base", so this patch didn't require any reindentation. :-)
Change-Id: Id8dc06683a69fad80d88e674f65e826d6a4e3f66
This converts "ordinary" breakpoint to use vtable_breakpoint_ops.
Recall that an ordinary breakpoint is both the kind normally created
by users, and also a base class used by other classes.
I noticed a few spots in GDB that use "typedef enum". However, in C++
this isn't as useful, as the tag is automatically entered as a
typedef. This patch removes most uses of "typedef enum" -- the
exceptions being in some nat-* code I can't compile, and
glibc_thread_db.h, which I think is more or less a copy of some C code
from elsewhere.
Tested by rebuilding.
Replace with calls to blockvector::blocks, and the appropriate method
call on the returned array_view.
Change-Id: I04d1f39603e4d4c21c96822421431d9a029d8ddd
Same idea as previous patch, but for symtab::objfile. I find
it clearer without this wrapper, as it shows that the objfile is
common to all symtabs of a given compunit. Otherwise, you could think
that each symtab (of a given compunit) can have a specific objfile.
Change-Id: Ifc0dbc7ec31a06eefa2787c921196949d5a6fcc6
symtab::blockvector is a wrapper around compunit_symtab::blockvector.
It is a bit misleadnig, as it gives the impression that a symtab has a
blockvector. Remove it, change all users to fetch the blockvector
through the compunit instead.
Change-Id: Ibd062cd7926112a60d52899dff9224591cbdeebf
Move 'struct reggroup' into the reggroups.h header. Remove the
reggroup_name and reggroup_type accessor functions, and just use the
name/type member functions within 'struct reggroup', update all uses
of these removed functions.
There should be no user visible changes after this commit.
Add a new function gdbarch_reggroups that returns a reference to a
vector containing all the reggroups for an architecture.
Make use of this function throughout GDB instead of the existing
reggroup_next and reggroup_prev functions.
Finally, delete the reggroup_next and reggroup_prev functions.
Most of these changes are pretty straight forward, using range based
for loops instead of the old style look using reggroup_next. There
are two places where the changes are less straight forward.
In gdb/python/py-registers.c, the register group iterator needed to
change slightly. As the iterator is tightly coupled to the gdbarch, I
just fetch the register group vector from the gdbarch when needed, and
use an index counter to find the next item from the vector when
needed.
In gdb/tui/tui-regs.c the tui_reg_next and tui_reg_prev functions are
just wrappers around reggroup_next and reggroup_prev respectively.
I've just inlined the logic of the old functions into the tui
functions. As the tui function had its own special twist (wrap around
behaviour) I think this is OK.
There should be no user visible changes after this commit.
While working on the disassembler I was getting frustrated. Every
time I touched disasm.h it seemed like every file in GDB would need to
be rebuilt. Surely the disassembler can't be required by that many
parts of GDB, right?
Turns out that disasm.h is included in target.h, so pretty much every
file was being rebuilt!
The only thing from disasm.h that target.h needed is the
gdb_disassembly_flag enum, as this is part of the target_ops api.
In this commit I move gdb_disassembly_flag into its own file. This is
then included in target.h and disasm.h, after which, the number of
files that depend on disasm.h is much reduced.
I also audited all the other includes of disasm.h and found that the
includes in mep-tdep.c and python/py-registers.c are no longer needed,
so I've removed these.
Now, after changing disasm.h, GDB rebuilds much quicker.
There should be no user visible changes after this commit.
Now that filtered and unfiltered output can be treated identically, we
can unify the printf family of functions. This is done under the name
"gdb_printf". Most of this patch was written by script.
Now that filtered and unfiltered output can be treated identically, we
can unify the puts family of functions. This is done under the name
"gdb_puts". Most of this patch was written by script.
New in this version:
- Rebase on master, fix a few more issues that appeared.
python-internal.h contains a number of macros that helped make the code
work with both Python 2 and 3. Remove them and adjust the code to use
the Python 3 functions.
Change-Id: I99a3d80067fb2d65de4f69f6473ba6ffd16efb2d
New in this version:
- Add a PY_MAJOR_VERSION check in configure.ac / AC_TRY_LIBPYTHON. If
the user passes --with-python=python2, this will cause a configure
failure saying that GDB only supports Python 3.
Support for Python 2 is a maintenance burden for any patches touching
Python support. Among others, the differences between Python 2 and 3
string and integer types are subtle. It requires a lot of effort and
thinking to get something that behaves correctly on both. And that's if
the author and reviewer of the patch even remember to test with Python
2.
See this thread for an example:
https://sourceware.org/pipermail/gdb-patches/2021-December/184260.html
So, remove Python 2 support. Update the documentation to state that GDB
can be built against Python 3 (as opposed to Python 2 or 3).
Update all the spots that use:
- sys.version_info
- IS_PY3K
- PY_MAJOR_VERSION
- gdb_py_is_py3k
... to only keep the Python 3 portions and drop the use of some
now-removed compatibility macros.
I did not update the configure script more than just removing the
explicit references to Python 2. We could maybe do more there, like
check the Python version and reject it if that version is not
supported. Otherwise (with this patch), things will only fail at
compile time, so it won't really be clear to the user that they are
trying to use an unsupported Python version. But I'm a bit lost in the
configure code that checks for Python, so I kept that for later.
Change-Id: I75b0f79c148afbe3c07ac664cfa9cade052c0c62
Add a new function, gdb.format_address, which is a wrapper around
GDB's print_address function.
This method takes an address, and returns a string with the format:
ADDRESS <SYMBOL+OFFSET>
Where, ADDRESS is the original address, formatted as hexadecimal,
SYMBOL is a symbol with an address lower than ADDRESS, and OFFSET is
the offset from SYMBOL to ADDRESS in decimal.
If there's no SYMBOL suitably close to ADDRESS then the
<SYMBOL+OFFSET> part is not included.
This is useful if a user wants to write a Python script that
pretty-prints addresses, the user no longer needs to do manual symbol
lookup, or worry about correctly formatting addresses.
Additionally, there are some settings that effect how GDB picks
SYMBOL, and whether the file name and line number should be included
with the SYMBOL name, the gdb.format_address function ensures that the
users Python script also benefits from these settings.
The gdb.format_address by default selects SYMBOL from the current
inferiors program space, and address is formatted using the
architecture for the current inferior. However, a user can also
explicitly pass a program space and architecture like this:
gdb.format_address(ADDRESS, PROGRAM_SPACE, ARCHITECTURE)
In order to format an address for a different inferior.
Notes on the implementation:
In py-arch.c I extended arch_object_to_gdbarch to add an assertion for
the type of the PyObject being worked on. Prior to this commit all
uses of arch_object_to_gdbarch were guaranteed to pass this function a
gdb.Architecture object, but, with this commit, this might not be the
case.
So, with this commit I've made it a requirement that the PyObject be a
gdb.Architecture, and this is checked with the assert. And in order
that callers from other files can check if they have a
gdb.Architecture object, I've added the new function
gdbpy_is_architecture.
In py-progspace.c I've added two new function, the first
progspace_object_to_program_space, converts a PyObject of type
gdb.Progspace to the associated program_space pointer, and
gdbpy_is_progspace checks if a PyObject is a gdb.Progspace or not.
The motivation for this patch is the fact that py-micmd.c doesn't build
with Python 2, due to PyDict_GetItemWithError being a Python 3-only
function:
CXX python/py-micmd.o
/home/smarchi/src/binutils-gdb/gdb/python/py-micmd.c: In function ‘int micmdpy_uninstall_command(micmdpy_object*)’:
/home/smarchi/src/binutils-gdb/gdb/python/py-micmd.c:430:20: error: ‘PyDict_GetItemWithError’ was not declared in this scope; did you mean ‘PyDict_GetItemString’?
430 | PyObject *curr = PyDict_GetItemWithError (mi_cmd_dict.get (),
| ^~~~~~~~~~~~~~~~~~~~~~~
| PyDict_GetItemString
A first solution to fix this would be to try to replace
PyDict_GetItemWithError equivalent Python 2 code. But I looked at why
we are doing this in the first place: it is to maintain the
`gdb._mi_commands` Python dictionary that we use as a `name ->
gdb.MICommand object` map. Since the `gdb._mi_commands` dictionary is
never actually used in Python, it seems like a lot of trouble to use a
Python object for this.
My first idea was to replace it with a C++ map
(std::unordered_map<std::string, gdbpy_ref<micmdpy_object>>). While
implementing this, I realized we don't really need this map at all. The
mi_command_py objects registered in the main MI command table can own
their backing micmdpy_object (that's a gdb.MICommand, but seen from the
C++ code). To know whether an mi_command is an mi_command_py, we can
use a dynamic cast. Since there's one less data structure to maintain,
there are less chances of messing things up.
- Change mi_command_py::m_pyobj to a gdbpy_ref, the mi_command_py is
now what keeps the MICommand alive.
- Set micmdpy_object::mi_command in the constructor of mi_command_py.
If mi_command_py manages setting/clearing that field in
swap_python_object, I think it makes sense that it also takes care of
setting it initially.
- Move a bunch of checks from micmdpy_install_command to
swap_python_object, and make them gdb_asserts.
- In micmdpy_install_command, start by doing an mi_cmd_lookup. This is
needed to know whether there's a Python MI command already registered
with that name. But we can already tell if there's a non-Python
command registered with that name. Return an error if that happens,
rather than waiting for insert_mi_cmd_entry to fail. Change the
error message to "name is already in use" rather than "may already be
in use", since it's more precise.
I asked Andrew about the original intent of using a Python dictionary
object to hold the command objects. The reason was to make sure the
objects get destroyed when the Python runtime gets finalized, not later.
Holding the objects in global C++ data structures and not doing anything
more means that the held Python objects will be decref'd after the
Python interpreter has been finalized. That's not desirable. I tried
it and it indeed segfaults.
Handle this by adding a gdbpy_finalize_micommands function called in
finalize_python. This is the mirror of gdbpy_initialize_micommands
called in do_start_initialization. In there, delete all Python MI
commands. I think it makes sense to do it this way: if it was somehow
possible to unload Python support from GDB in the middle of a session
we'd want to unregister any Python MI command. Otherwise, these MI
commands would be backed with a stale PyObject or simply nothing.
Delete tests that were related to `gdb._mi_commands`.
Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I060d5ebc7a096c67487998a8a4ca1e8e56f12cd3
GDB notifies users about user selected thread changes somewhat
inconsistently as mentioned on gdb-patches mailing list here:
https://sourceware.org/pipermail/gdb-patches/2022-February/185989.html
Consider GDB debugging a multi-threaded inferior with both CLI and GDB/MI
interfaces connected to separate terminals.
Assuming inferior is stopped and thread 1 is selected, when a thread
2 is selected using '-thread-select 2' command on GDB/MI terminal:
-thread-select 2
^done,new-thread-id="2",frame={level="0",addr="0x00005555555551cd",func="child_sub_function",args=[],file="/home/jv/Projects/gdb/users_jv_patches/gdb/testsuite/gdb.mi/user-selected-context-sync.c",fullname="/home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c",line="30",arch="i386:x86-64"}
(gdb)
and on CLI terminal we get the notification (as expected):
[Switching to thread 2 (Thread 0x7ffff7daa640 (LWP 389659))]
#0 child_sub_function () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30
30 volatile int dummy = 0;
However, now that thread 2 is selected, if thread 1 is selected
using 'thread-select --thread 1 1' command on GDB/MI terminal
terminal:
-thread-select --thread 1 1
^done,new-thread-id="1",frame={level="0",addr="0x0000555555555294",func="main",args=[],file="/home/jv/Projects/gdb/users_jv_patches/gdb/testsuite/gdb.mi/user-selected-context-sync.c",fullname="/home/jv/Projects/gdb/users_jv_patches/gdb/testsuite/gdb.mi/user-selected-context-sync.c",line="66",arch="i386:x86-64"}
(gdb)
but no notification is printed on CLI terminal, despite the fact
that user selected thread has changed.
The problem is that when `-thread-select --thread 1 1` is executed
then thread is switched to thread 1 before mi_cmd_thread_select () is
called, therefore the condition "inferior_ptid != previous_ptid"
there does not hold.
To address this problem, we have to move notification logic up to
mi_cmd_execute () where --thread option is processed and notify
user selected contents observers there if context changes.
However, this in itself breaks GDB/MI because it would cause context
notification to be sent on MI channel. This is because by the time
we notify, MI notification suppression is already restored (done in
mi_command::invoke(). Therefore we had to lift notification suppression
logic also up to mi_cmd_execute (). This change in made distinction
between mi_command::invoke() and mi_command::do_invoke() unnecessary
as all mi_command::invoke() did (after the change) was to call
do_invoke(). So this patches removes do_invoke() and moves the command
execution logic directly to invoke().
With this change, all gdb.mi tests pass, tested on x86_64-linux.
Co-authored-by: Andrew Burgess <aburgess@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=20631
This commit allows a user to create custom MI commands using Python
similarly to what is possible for Python CLI commands.
A new subclass of mi_command is defined for Python MI commands,
mi_command_py. A new file, gdb/python/py-micmd.c contains the logic
for Python MI commands.
This commit is based on work linked too from this mailing list thread:
https://sourceware.org/pipermail/gdb/2021-November/049774.html
Which has also been previously posted to the mailing list here:
https://sourceware.org/pipermail/gdb-patches/2019-May/158010.html
And was recently reposted here:
https://sourceware.org/pipermail/gdb-patches/2022-January/185190.html
The version in this patch takes some core code from the previously
posted patches, but also has some significant differences, especially
after the feedback given here:
https://sourceware.org/pipermail/gdb-patches/2022-February/185767.html
A new MI command can be implemented in Python like this:
class echo_args(gdb.MICommand):
def invoke(self, args):
return { 'args': args }
echo_args("-echo-args")
The 'args' parameter (to the invoke method) is a list
containing (almost) all command line arguments passed to the MI
command (--thread and --frame are handled before the Python code is
called, and removed from the args list). This list can be empty if
the MI command was passed no arguments.
When used within gdb the above command produced output like this:
(gdb)
-echo-args a b c
^done,args=["a","b","c"]
(gdb)
The 'invoke' method of the new command must return a dictionary. The
keys of this dictionary are then used as the field names in the mi
command output (e.g. 'args' in the above).
The values of the result returned by invoke can be dictionaries,
lists, iterators, or an object that can be converted to a string.
These are processed recursively to create the mi output. And so, this
is valid:
class new_command(gdb.MICommand):
def invoke(self,args):
return { 'result_one': { 'abc': 123, 'def': 'Hello' },
'result_two': [ { 'a': 1, 'b': 2 },
{ 'c': 3, 'd': 4 } ] }
Which produces output like:
(gdb)
-new-command
^done,result_one={abc="123",def="Hello"},result_two=[{a="1",b="2"},{c="3",d="4"}]
(gdb)
I have required that the fields names used in mi result output must
match the regexp: "^[a-zA-Z][-_a-zA-Z0-9]*$" (without the quotes).
This restriction was never written down anywhere before, but seems
sensible to me, and we can always loosen this rule later if it proves
to be a problem. Much harder to try and add a restriction later, once
people are already using the API.
What follows are some details about how this implementation differs
from the original patch that was posted to the mailing list.
In this patch, I have changed how the lifetime of the Python
gdb.MICommand objects is managed. In the original patch, these object
were kept alive by an owned reference within the mi_command_py object.
As such, the Python object would not be deleted until the
mi_command_py object itself was deleted.
This caused a problem, the mi_command_py were held in the global mi
command table (in mi/mi-cmds.c), which, as a global, was not cleared
until program shutdown. By this point the Python interpreter has
already been shutdown. Attempting to delete the mi_command_py object
at this point was causing GDB to try and invoke Python code after
finalising the Python interpreter, and we would crash.
To work around this problem, the original patch added code in
python/python.c that would search the mi command table, and delete the
mi_command_py objects before the Python environment was finalised.
In contrast, in this patch, I have added a new global dictionary to
the gdb module, gdb._mi_commands. We already have several such global
data stores related to pretty printers, and frame unwinders.
The MICommand objects are placed into the new gdb.mi_commands
dictionary, and it is this reference that keeps the objects alive.
When GDB's Python interpreter is shut down gdb._mi_commands is deleted,
and any MICommand objects within it are deleted at this point.
This change avoids having to make the mi_cmd_table global, and walk
over it from within GDB's python related code.
This patch handles command redefinition entirely within GDB's python
code, though this does impose one small restriction which is not
present in the original code (detailed below), I don't think this is a
big issue. However, the original patch relied on being able to
finish executing the mi_command::do_invoke member function after the
mi_command object had been deleted. Though continuing to execute a
member function after an object is deleted is well defined, it is
also (IMHO) risky, its too easy for someone to later add a use of the
object without realising that the object might sometimes, have been
deleted. The new patch avoids this issue.
The one restriction that is added to avoid this, is that an MICommand
object can't be reinitialised with a different command name, so:
(gdb) python cmd = MyMICommand("-abc")
(gdb) python cmd.__init__("-def")
can't reinitialize object with a different command name
This feels like a pretty weird edge case, and I'm happy to live with
this restriction.
I have also changed how the memory is managed for the command name.
In the most recently posted patch series, the command name is moved
into a subclass of mi_command, the python mi_command_py, which
inherits from mi_command is then free to use a smart pointer to manage
the memory for the name.
In this patch, I leave the mi_command class unchanged, and instead
hold the memory for the name within the Python object, as the lifetime
of the Python object always exceeds the c++ object stored in the
mi_cmd_table. This adds a little more complexity in py-micmd.c, but
leaves the mi_command class nice and simple.
Next, this patch adds some extra functionality, there's a
MICommand.name read-only attribute containing the name of the command,
and a read-write MICommand.installed attribute that can be used to
install (make the command available for use) and uninstall (remove the
command from the mi_cmd_table so it can't be used) the command. This
attribute will be automatically updated if a second command replaces
an earlier command.
This patch adds additional error handling, and makes more use the
gdbpy_handle_exception function.
Co-Authored-By: Jan Vrany <jan.vrany@labware.com>
Add a new read-only property, Type.is_signed, which is True for signed
types, and False otherwise.
This property should only be read on types for which Type.is_scalar is
true, attempting to read this property for non-scalar types will raise
a ValueError.
I chose 'is_signed' rather than 'is_unsigned' in order to match the
existing Architecture.integer_type method, which takes a 'signed'
parameter. As far as I could find, that was the only existing
signed/unsigned selector in the Python API, so it seemed reasonable to
stay consistent.
