error reading variable on Windows Docker Containers

Jonah Graham jonah@kichwacoders.com
Fri Nov 15 18:23:00 GMT 2019


On Fri, 15 Nov 2019 at 12:59, J.R. Heisey <jrheisey@raytheon.com> wrote:

> Why are you quoting the variable name?
>

I am not, I am printing literal character 'Z'. Note in the full log I am
not even debugging a program, just starting gdb and doing p 'Z'.


>
> Thanks,
> J.R.
> SVO 460 Room 167
> X2949
>
>
> -----Original Message-----
> From: gdb-owner@sourceware.org <gdb-owner@sourceware.org> On Behalf Of
> Jonah Graham
> Sent: Friday, November 15, 2019 9:20 AM
> To: GDB Development <gdb@sourceware.org>
> Subject: [External] error reading variable on Windows Docker Containers
>
> Hello folks,
>
> I have a strange error using GDB on a Windows Docker container and I don't
> know where to start in diagnosing the problem.
>
> Simply, when trying to print characters or strings I get "error reading
> variable". For example:
>
> (gdb) p 'Z'
> $1 = 90 '<error reading variable>
> instead of:
> $1 = 90 'Z'
>
> Full log below. This is running a Windows Docker container (FROM
> mcr.microsoft.com/windows/servercore:1809) using msys2's distribution of
> mingw-w64-x86_64-gdb.
>
>
> Full command and output:
>
> gdb -ex "p 'Z'" -ex "p/x 'Z'" -ex "p \"abcd\"" -ex "quit"
> GNU gdb (GDB) 8.3.1
> Copyright (C) 2019 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <
> http://gnu.org/licenses/gpl.html
> >
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.
> Type "show copying" and "show warranty" for details.
> This GDB was configured as "x86_64-w64-mingw32".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
> Find the GDB manual and other documentation resources online at:
>     <http://www.gnu.org/software/gdb/documentation/>.
>
> For help, type "help".
> Type "apropos word" to search for commands related to "word".
> $1 = 90 '<error reading variable>
> $2 = 0x5a
> $3 = <error reading variable>
>
> What I expect, and what I get on the same version of Windows Pro (1809)
> with the identical GDB when running on the host OS is:
>
> $1 = 90 'Z'
> $2 = 0x5a
> $3 = "abcd"
>
> Any guidance greatly welcome.
>
> PS for those of you who might wonder why, I am in the process of setting
> up regression tests on Windows for a VS Code Debug Adapter for GDB by the
> Eclipse CDT project: https://github.com/eclipse-cdt/cdt-gdb-adapter. I am
> hoping to run these tests in a container to improve reproducibility. At the
> moment our tests pass, except the ones for variables.
>
> Thank you,
> Jonah
>
>
> ~~~
> Jonah Graham
> Kichwa Coders
> www.kichwacoders.com
>



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