Re: [PATCH v3] Implement $_exitsignal

[Sergio Durigan Junior <sergiodj at redhat dot com>]

On Sunday, August 25 2013, I wrote:

> Hi,
>
> This is the third attempt to implement the new convenience variable
> $_exitsignal.  You can take a look at the other attempts in the
> following threads:

Ping.

> - First attempt:
>   <http://sourceware.org/ml/gdb-patches/2013-06/msg00352.html>
>
> - Second attempt:
>   <http://sourceware.org/ml/gdb-patches/2013-06/msg00452.html>
>
> I have addressed all the comments, probably except for Tom's message:
>
>   <https://sourceware.org/ml/gdb-patches/2013-07/msg00456.html>
>
> Because of another internal discussion we had, when we decided that it
> would be better to leave things this way for now, i.e., $_exitcode and
> $_exitsignal separated.
>
> I have also added code to create the $_exitsignal variable when a
> corefile is opened, and to make $_exitcode become void in that case,
> as explained by myself in:
>
>   <https://sourceware.org/ml/gdb-patches/2013-06/msg00473.html>
>
> Now I guess everything makes sense, since we are correctly dealing
> with $_exitsignal and $_exitcode in a mutually exclusive way.  There
> is still the $_signo patch to be made, but this one will come later.
>
> OK to apply?  I'd appreciate comments, if you have any.
>
> -- 
> Sergio
>
> gdb/
> 2013-08-25  Sergio Durigan Junior  <sergiodj@redhat.com>
>
> 	* NEWS: Mention new convenience variable $_exitsignal.
> 	* corelow.c (core_open): Set $_exitsignal to the uncaught signal
> 	which generated the corefile; reset $_exitcode to void.
> 	* infrun.c (handle_inferior_event): Reset $_exitsignal for
> 	TARGET_WAITKIND_EXITED; set $_exitsignal and reset $_exitcode for
> 	TARGET_WAITKIND_SIGNALLED.
>
> gdb/testsuite
> 2013-08-25  Sergio Durigan Junior  <sergiodj@redhat.com>
>
> 	* gdb.base/corefile.exp: Test whether $_exitsignal is set and
> 	$_exitcode is void when opening a corefile.
> 	* gdb.base/exitsignal.exp: New file.
> 	* gdb.base/segv.c: Likewise.
> 	* gdb.base/normal.c: Likewise.
>
> gdb/doc
> 2013-08-25  Sergio Durigan Junior  <sergiodj@redhat.com>
>
> 	* gdb.texinfo (Convenience Variables): Document $_exitsignal.
> 	Update entry for $_exitcode.
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index f246ee1..fb113dc 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -77,6 +77,10 @@ show range-stepping
>  * The exception-related catchpoints, like "catch throw", now accept a
>    regular expression which can be used to filter exceptions by type.
>  
> +* The new convenience variable $_exitsignal is automatically set to
> +  the terminating signal number when the program being debugged dies
> +  due to an uncaught signal.
> +
>  * MI changes
>  
>    ** The -trace-save MI command can optionally save trace buffer in Common
> diff --git a/gdb/corelow.c b/gdb/corelow.c
> index 8371b58..ef231d1 100644
> --- a/gdb/corelow.c
> +++ b/gdb/corelow.c
> @@ -446,6 +446,16 @@ core_open (char *filename, int from_tty)
>  
>        printf_filtered (_("Program terminated with signal %s, %s.\n"),
>  		       gdb_signal_to_name (sig), gdb_signal_to_string (sig));
> +
> +      /* Set the value of the internal variable $_exitsignal,
> +	 which holds the signal uncaught by the inferior.  */
> +      set_internalvar_integer (lookup_internalvar ("_exitsignal"),
> +			       siggy);
> +
> +      /* Clear the $_exitcode internal variable, because if the
> +	 inferior died with a signal then its return code does not
> +	 exist.  */
> +      clear_internalvar (lookup_internalvar ("_exitcode"));
>      }
>  
>    /* Fetch all registers from core file.  */
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 6d5dec4..8157447 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -9751,8 +9751,15 @@ to match the format in which the data was printed.
>  
>  @item $_exitcode
>  @vindex $_exitcode@r{, convenience variable}
> -The variable @code{$_exitcode} is automatically set to the exit code when
> -the program being debugged terminates.
> +When the program being debugged terminates normally, @value{GDBN}
> +automatically sets this variable to the exit code of the program, and
> +resets @code{$_exitsignal} to @code{void}.
> +
> +@item $_exitsignal
> +@vindex $_exitsignal@r{, convenience variable}
> +When the program being debugged dies due to an uncaught signal,
> +@value{GDBN} automatically sets this variable to that signal's number,
> +and resets @code{$_exitcode} to @code{void}.
>  
>  @item $_exception
>  The variable @code{$_exception} is set to the exception object being
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index dc1036d..b55c65c 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -3428,6 +3428,10 @@ handle_inferior_event (struct execution_control_state *ecs)
>  	  set_internalvar_integer (lookup_internalvar ("_exitcode"),
>  				   (LONGEST) ecs->ws.value.integer);
>  
> +	  /* Clear the $_exitsignal internal variable, since if we are
> +	     here the inferior has not been terminated by a signal.  */
> +	  clear_internalvar (lookup_internalvar ("_exitsignal"));
> +
>  	  /* Also record this in the inferior itself.  */
>  	  current_inferior ()->has_exit_code = 1;
>  	  current_inferior ()->exit_code = (LONGEST) ecs->ws.value.integer;
> @@ -3435,7 +3439,43 @@ handle_inferior_event (struct execution_control_state *ecs)
>  	  print_exited_reason (ecs->ws.value.integer);
>  	}
>        else
> -	print_signal_exited_reason (ecs->ws.value.sig);
> +	{
> +	  LONGEST signo;
> +	  struct regcache *regcache = get_thread_regcache (ecs->ptid);
> +	  struct gdbarch *gdbarch = get_regcache_arch (regcache);
> +
> +	  if (gdbarch_gdb_signal_to_target_p (gdbarch))
> +	    signo = (LONGEST) gdbarch_gdb_signal_to_target (gdbarch,
> +							    ecs->ws.value.sig);
> +	  else if (gdb_signal_to_host_p (ecs->ws.value.sig))
> +	    {
> +	      /* This is a workaround.  If we don't have a way to a
> +		 way of converting a signal using the target's
> +		 notation (which is the best), then we at least offer
> +		 the conversion using the host's notation.  This will
> +		 be OK as long as the user is not doing remote
> +		 debugging with target != host.  */
> +	      signo = (LONGEST) gdb_signal_to_host (ecs->ws.value.sig);
> +	    }
> +	  else
> +	    {
> +	      /* This is *ugly*, but if we can't even rely on the host
> +		 converstion, then the least we can do is to print
> +		 GDB's internal signal number.  */
> +	      signo = (LONGEST) ecs->ws.value.sig;
> +	    }
> +
> +	  print_signal_exited_reason (ecs->ws.value.sig);
> +	  /* Set the value of the internal variable $_exitsignal,
> +	     which holds the signal uncaught by the inferior.  */
> +	  set_internalvar_integer (lookup_internalvar ("_exitsignal"),
> +				   signo);
> +
> +	  /* Clear the $_exitcode internal variable, because if the
> +	     inferior died with a signal then its return code does not
> +	     exist.  */
> +	  clear_internalvar (lookup_internalvar ("_exitcode"));
> +	}
>  
>        gdb_flush (gdb_stdout);
>        target_mourn_inferior ();
> diff --git a/gdb/testsuite/gdb.base/corefile.exp b/gdb/testsuite/gdb.base/corefile.exp
> index 24a33a3..77ef954 100644
> --- a/gdb/testsuite/gdb.base/corefile.exp
> +++ b/gdb/testsuite/gdb.base/corefile.exp
> @@ -142,6 +142,16 @@ gdb_test "print coremaker_ro" "\\\$$decimal = 201"
>  
>  gdb_test "print func2::coremaker_local" "\\\$$decimal = \\{0, 1, 2, 3, 4\\}"
>  
> +# Test the presence and the correct values of $_exitsignal and
> +# $_exitcode variables.  The corefile is generated with a SIGABRT,
> +# which is "6" in the Linux kernel.
> +
> +gdb_test "print \$_exitsignal" " = 6" \
> +    "\$_exitsignal prints SIGABRT (6)"
> +
> +gdb_test "print \$_exitcode" " = void" \
> +    "\$_exitcode is void"
> +
>  # Somehow we better test the ability to read the registers out of the core
>  # file correctly.  I don't think the other tests do this.
>  
> diff --git a/gdb/testsuite/gdb.base/exitsignal.exp b/gdb/testsuite/gdb.base/exitsignal.exp
> new file mode 100644
> index 0000000..5ab2fee
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/exitsignal.exp
> @@ -0,0 +1,97 @@
> +# Copyright 2013 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/>.
> +
> +# This test checks both $_exitcode and $_exitsignal variables.  The
> +# purpose of this checking is to ensure that the variables are
> +# mutually exclusive, i.e., that when $_exitsignal is set, $_exitcode
> +# is not, and vice-versa.  This mutual exclusion happens because if an
> +# inferior exited (either successfuly or not), it certainly was not
> +# killed by a signal.  However, if it was killed by an uncaught
> +# signal, then there is no way for it to have exited.
> +
> +standard_testfile segv.c
> +
> +if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
> +    return -1
> +}
> +
> +# Run to main
> +if { ![runto_main] } {
> +    return -1
> +}
> +
> +# Print $_exitsignal.  It should be void now, because nothing
> +# happened.
> +gdb_test "print \$_exitsignal" " = void" \
> +    "\$_exitsignal is void before running"
> +
> +# Just to guarantee, making sure that $_exitcode is also void.
> +gdb_test "print \$_exitcode" " = void" \
> +    "\$_exitcode is void before running"
> +
> +# Trigger SIGSEGV.
> +gdb_test "continue" "Program received signal SIGSEGV.*" "trigger SIGSEGV"
> +
> +# Continue until the end.
> +gdb_test "continue" "Program terminated with signal SIGSEGV.*" \
> +    "program terminated with SIGSEGV"
> +
> +# Now, print $_exitsignal again.  It should be 11 (SIGSEGV).
> +gdb_test "print \$_exitsignal" " = 11" \
> +    "\$_exitsignal is 11 (SIGSEGV) after SIGSEGV."
> +
> +# And $_exitcode should still be void, since the inferior died because
> +# of a signal, and did not return.
> +gdb_test "print \$_exitcode" " = void" \
> +    "\$_exitcode is still void after SIGSEGV"
> +
> +# Re-run to main, i.e., restart the executable.
> +rerun_to_main
> +
> +# Print the $_exitsignal again.  Even in this normal scenario, it
> +# should still contain the signal triggered in the other run.
> +gdb_test "print \$_exitsignal" " = 11" \
> +    "\$_exitsignal is 11 (SIGSEGV) after restarting the inferior"
> +
> +# And, again, print $_exitcode.
> +gdb_test "print \$_exitcode" " = void" \
> +    "\$_exitcode is still void after restarting the inferior"
> +
> +# Now we test the behaviour of $_exit{code,signal} during a normal
> +# inferior execution.
> +standard_testfile normal.c
> +
> +if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
> +    return -1
> +}
> +
> +# Checking $_exitsignal and $_exitcode, both should be void before the
> +# inferior is executed.
> +gdb_test "print \$_exitsignal" " = void" \
> +    "\$_exitsignal is void before normal inferior is executed"
> +gdb_test "print \$_exitcode" " = void" \
> +    "\$_exitcode is void before normal inferior is executed"
> +
> +# Running until the end.
> +gdb_test "run" "\\\[Inferior .* exited normally\\\]" "Run inferior until the end"
> +
> +# Checking $_exitcode.  It should be 0.
> +gdb_test "print \$_exitcode" " = 0" \
> +    "\$_exitcode is zero after normal inferior is executed"
> +
> +# Checking $_exitsignal.  It should still be void, since the inferior
> +# has not received any signal.
> +gdb_test "print \$_exitsignal" " = void" \
> +    "\$_exitsignal is still void after normal inferior is executed"
> diff --git a/gdb/testsuite/gdb.base/normal.c b/gdb/testsuite/gdb.base/normal.c
> new file mode 100644
> index 0000000..4aa7c45
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/normal.c
> @@ -0,0 +1,24 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2013 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/>.  */
> +
> +/* This test is just a normal return 0.  */
> +
> +int
> +main (int argc, char *argv[])
> +{
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.base/segv.c b/gdb/testsuite/gdb.base/segv.c
> new file mode 100644
> index 0000000..8991f4d
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/segv.c
> @@ -0,0 +1,29 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2013 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/>.  */
> +
> +/* This test can be used just to generate a SIGSEGV.  */
> +
> +#include <signal.h>
> +
> +int
> +main (int argc, char *argv[])
> +{
> +  /* Generating a SIGSEGV.  */
> +  raise (SIGSEGV);
> +
> +  return 0;
> +}

-- 
Sergio