[RFC] (windows) GDB/MI crash when using "-list-thread-groups --available"
Commit Message
Hi Pedro,
> It looks good to me. A few comments on minor details follow.
>
> How about naming the testcase list-thread-groups-no-inferior.exp
> (no "mi-") so that it sits side-by-side with
> list-thread-groups-available.exp?
Good idea. Done.
> We're missing an intro comment in the .exp file mentioning what the
> testcase is about, otherwise it's not clear why we have two separate
> testcases for seemingly the same thing.
Also added. Let me know if you think it's not enough information,
and I will add more. That's all I could think of from my perspective,
though.
> A couple microscopic nits more:
>
> > +gdb_test_multiple $test $test {
> > + -re ".*\}" {
>
> Leading ".*" is not necessary, it's implied.
Thanks - fixed!
>
> > +mi_gdb_test "-data-evaluate-expression 1" \
> > + ".*\\^done,value=\"1\"" \
> > + "check GDB is still alive"
> > +
>
> "check" and "test" in test messages is one of my pet peeves.
> OK, I'm really exaggerating. :-) The point is that all
> tests are checking something, making it redundant.
> "GDB is still alive" or even "GDB is alive" says the same.
True, and I like it when it's shorter-with-no-loss. Fixed as well.
Attached is the version I just pushed. I'll make further adjustments
if you see something I missed or the description isn't complete for you.
Thanks again!
From 178d6a638693d1a7a66b0553f16b1df95b4f27ee Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Mon, 4 Jun 2018 15:03:32 -0500
Subject: [PATCH] (windows) GDB/MI crash when using "-list-thread-groups
--available"
On Windows, using the "-list-thread-groups --available" GDB/MI command
before an inferior is being debugged:
% gdb -q -i=mi
=thread-group-added,id="i1"
=cmd-param-changed,param="auto-load safe-path",value="/"
(gdb)
-list-thread-groups --available
Segmentation fault
Ooops!
The SEGV happens because the -list-thread-groups --available command
triggers a windows_nat_target::xfer_partial call for a TARGET_OBJECT_OSDATA
object. Until a program is being debugged, the target_ops layer that
gets the call is the Windows "native" layer. Except for a couple of
specific objects (TARGET_OBJECT_MEMORY and TARGET_OBJECT_LIBRARIES),
this layer's xfer_partial method delegates the xfer of other objects
to the target beneath:
default:
return beneath->xfer_partial (object, annex,
readbuf, writebuf, offset, len,
xfered_len);
Unfortunately, there is no "beneath layer" in this case, so
beneath is NULL and dereferencing it leads to the SEGV.
This patch fixes the issue by checking beneath before trying
to delegate the request.
gdb/ChangeLog:
* windows-nat.c (windows_nat_target::xfer_partial): Return
TARGET_XFER_E_IO if we need to delegate to the target beneath
but BENEATH is NULL.
gdb/testsuite/ChangeLog:
* gdb.mi/list-thread-groups-no-inferior.exp: New testcase.
---
gdb/ChangeLog | 6 +++
gdb/testsuite/ChangeLog | 4 ++
.../gdb.mi/list-thread-groups-no-inferior.exp | 47 ++++++++++++++++++++++
gdb/windows-nat.c | 7 ++++
4 files changed, 64 insertions(+)
create mode 100644 gdb/testsuite/gdb.mi/list-thread-groups-no-inferior.exp
@@ -1,3 +1,9 @@
+2018-06-04 Joel Brobecker <brobecker@adacore.com>
+
+ * windows-nat.c (windows_nat_target::xfer_partial): Return
+ TARGET_XFER_E_IO if we need to delegate to the target beneath
+ but BENEATH is NULL.
+
2018-06-04 Simon Marchi <simon.marchi@ericsson.com>
* Makefile.in (config.status): Add configure.nat as a
@@ -1,3 +1,7 @@
+2018-06-04 Joel Brobecker <brobecker@adacore.com>
+
+ * gdb.mi/list-thread-groups-no-inferior.exp: New testcase.
+
2018-06-01 Joel Brobecker <brobecker@adacore.com>
* gdb.ada/bp_fun_addr: New testcase.
new file mode 100644
@@ -0,0 +1,47 @@
+# Copyright 2018 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# The purpose of this test is to verify that GDB is able to handle
+# the "-list-thread-groups --available" command, even when there is
+# no inferior. In particular, we want to verify that GDB does not
+# crash.
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+gdb_exit
+if [mi_gdb_start] {
+ continue
+}
+
+# Try the "-list-thread-groups --available". This command can generate
+# a very large amount of output, potentially exceeding expect's buffer
+# size. So we consume the output in chunks.
+
+set test "-list-thread-groups --available"
+gdb_test_multiple $test $test {
+ -re "\}" {
+ exp_continue
+ }
+ -re "\r\n$gdb_prompt " {
+ pass $test
+ }
+}
+
+# Verify that GDB is still alive.
+
+mi_gdb_test "-data-evaluate-expression 1" \
+ ".*\\^done,value=\"1\"" \
+ "GDB is still alive"
@@ -2966,6 +2966,13 @@ windows_nat_target::xfer_partial (enum target_object object,
writebuf, offset, len, xfered_len);
default:
+ if (beneath == NULL)
+ {
+ /* This can happen when requesting the transfer of unsupported
+ objects before a program has been started (and therefore
+ with the current_target having no target beneath). */
+ return TARGET_XFER_E_IO;
+ }
return beneath->xfer_partial (object, annex,
readbuf, writebuf, offset, len,
xfered_len);
--
2.11.0