Re: [PATCH 1/3] Fix "run" failure with GDBserver

[Lancelot SIX <lancelot.six@amd.com>]

Hi Pedro,

On Mon, Feb 12, 2024 at 08:01:51PM +0000, Pedro Alves wrote:
> If starting the inferior process with "run" (vRun packet) fails,
> GDBserver throws an error that escapes all the way to the top level.
> When an error escapes all the way like that, GDBserver interprets it
> as a disconnection, and either goes back to waiting for a new GDB
> connection, or exits, if --once was specified.
> 
> E.g., with the testcase program added by this commit, we see:
> 
> On GDB side:
> 
>  ...
>  (gdb) tar extended-remote :999
>  ...
>  Remote debugging using :9999
>  (gdb) r
>  Starting program:
>  Running ".../gdb.base/run-fail-twice/run-fail-twice.nox" on the remote target failed
>  (gdb)
> 
> On GDBserver side:
> 
>  $ gdbserver --once --multi :9999
>  Remote debugging from host 127.0.0.1, port 34344
>  bash: line 1: .../gdb.base/run-fail-twice/run-fail-twice.nox: Permission denied
>  bash: line 1: exec: .../gdb.base/run-fail-twice/run-fail-twice.nox: cannot execute: Permission denied
>  gdbserver: During startup program exited with code 126.
>  $   # gdbserver exited
> 
> This is wrong, as we've connected with extended-remote/--multi.
> GDBserver should just report an error to vCont, and continue connected
> to GDB, waiting for other commands.
> 
> This commit fixes GDBserver by catching the error locally in
> handle_v_run.
> 
> Change-Id: Ib386f267522603f554b52a885b15229c9639e870
> ---
>  gdb/testsuite/gdb.base/run-fail-twice.exp | 67 +++++++++++++++++++++++
>  gdbserver/server.cc                       | 10 +++-
>  2 files changed, 76 insertions(+), 1 deletion(-)
>  create mode 100644 gdb/testsuite/gdb.base/run-fail-twice.exp
> 

Looks like you forgot the gdb/testsuite/gdb.base/run-fail-twice.c file?

> diff --git a/gdb/testsuite/gdb.base/run-fail-twice.exp b/gdb/testsuite/gdb.base/run-fail-twice.exp
> new file mode 100644
> index 00000000000..2fda5c9fde5
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/run-fail-twice.exp
> @@ -0,0 +1,67 @@
> +# Copyright 2024 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/>.
> +
> +# Test doing a "run" that fails, and then another "run".
> +
> +# The purpose of this testcase is to test the "run" command.  If we
> +# cannot use it, then there is no point in running this testcase.
> +require !use_gdb_stub
> +
> +standard_testfile
> +
> +if {[build_executable "failed to build" $testfile $srcfile {debug}]} {
> +    return -1
> +}
> +
> +proc test_run {testname} {
> +    gdb_run_cmd
> +    gdb_test_multiple "" $testname {
> +	-re -wrap "During startup program exited with code 126\\." {
> +	    # What we get on GNU/Linux.
> +	    pass $gdb_test_name
> +	}
> +	-re -wrap "Error creating process.*" {
> +	    # What we get on Windows.
> +	    pass $gdb_test_name
> +	}
> +	-re -wrap "Running .* on the remote target failed" {
> +	    # What we get with older GDBserver and other remote
> +	    # targets.
> +	    pass $gdb_test_name
> +	}
> +    }
> +}
> +
> +proc_with_prefix test {} {
> +    global gdb_prompt binfile
> +
> +    clean_restart $binfile
> +
> +    gdb_test_no_output "set confirm off"
> +
> +    gdb_remote_download host $binfile $binfile.nox
> +    remote_exec target "chmod \"a-x\" $binfile.nox"
> +    gdb_test "exec-file $binfile.nox" \

Couldn't you use gdb_test_no_output and remove the 2nd argument?

> +	"" \
> +	"exec-file \$binfile.nox"
> +    gdb_test "set remote exec-file $binfile.nox" \
> +	"" \

Same here.

> +	"set remote exec-file \$binfile.nox"
> +
> +    test_run "bad run 1"
> +    test_run "bad run 2"
> +}
> +
> +test
> diff --git a/gdbserver/server.cc b/gdbserver/server.cc
> index e02cdb83b51..0967b194376 100644
> --- a/gdbserver/server.cc
> +++ b/gdbserver/server.cc
> @@ -3025,7 +3025,15 @@ handle_v_run (char *own_buf)
>    free_vector_argv (program_args);
>    program_args = new_argv;
>  
> -  target_create_inferior (program_path.get (), program_args);
> +  try
> +    {
> +      target_create_inferior (program_path.get (), program_args);
> +    }
> +  catch (const gdb_exception_error &exception)
> +    {
> +      sprintf (own_buf, "E.%s", exception.what ());
> +      return;
> +    }
>  
>    if (cs.last_status.kind () == TARGET_WAITKIND_STOPPED)
>      {
> 
> -- 
> 2.43.0
> 

Best,
Lancelot