492d29ea1c
This patch splits the TRY_CATCH macro into three, so that we go from
this:
~~~
volatile gdb_exception ex;
TRY_CATCH (ex, RETURN_MASK_ERROR)
{
}
if (ex.reason < 0)
{
}
~~~
to this:
~~~
TRY
{
}
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
~~~
Thus, we'll be getting rid of the local volatile exception object, and
declaring the caught exception in the catch block.
This allows reimplementing TRY/CATCH in terms of C++ exceptions when
building in C++ mode, while still allowing to build GDB in C mode
(using setjmp/longjmp), as a transition step.
TBC, after this patch, is it _not_ valid to have code between the TRY
and the CATCH blocks, like:
TRY
{
}
// some code here.
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
Just like it isn't valid to do that with C++'s native try/catch.
By switching to creating the exception object inside the CATCH block
scope, we can get rid of all the explicitly allocated volatile
exception objects all over the tree, and map the CATCH block more
directly to C++'s catch blocks.
The majority of the TRY_CATCH -> TRY+CATCH+END_CATCH conversion was
done with a script, rerun from scratch at every rebase, no manual
editing involved. After the mechanical conversion, a few places
needed manual intervention, to fix preexisting cases where we were
using the exception object outside of the TRY_CATCH block, and cases
where we were using "else" after a 'if (ex.reason) < 0)' [a CATCH
after this patch]. The result was folded into this patch so that GDB
still builds at each incremental step.
END_CATCH is necessary for two reasons:
First, because we name the exception object in the CATCH block, which
requires creating a scope, which in turn must be closed somewhere.
Declaring the exception variable in the initializer field of a for
block, like:
#define CATCH(EXCEPTION, mask) \
for (struct gdb_exception EXCEPTION; \
exceptions_state_mc_catch (&EXCEPTION, MASK); \
EXCEPTION = exception_none)
would avoid needing END_CATCH, but alas, in C mode, we build with C90,
which doesn't allow mixed declarations and code.
Second, because when TRY/CATCH are wired to real C++ try/catch, as
long as we need to handle cleanup chains, even if there's no CATCH
block that wants to catch the exception, we need for stop at every
frame in the unwind chain and run cleanups, then rethrow. That will
be done in END_CATCH.
After we require C++, we'll still need TRY/CATCH/END_CATCH until
cleanups are completely phased out -- TRY/CATCH in C++ mode will
save/restore the current cleanup chain, like in C mode, and END_CATCH
catches otherwise uncaugh exceptions, runs cleanups and rethrows, so
that C++ cleanups and exceptions can coexist.
IMO, this still makes the TRY/CATCH code look a bit more like a
newcomer would expect, so IMO worth it even if we weren't considering
C++.
gdb/ChangeLog.
2015-03-07 Pedro Alves <palves@redhat.com>
* common/common-exceptions.c (struct catcher) <exception>: No
longer a pointer to volatile exception. Now an exception value.
<mask>: Delete field.
(exceptions_state_mc_init): Remove all parameters. Adjust.
(exceptions_state_mc): No longer pop the catcher here.
(exceptions_state_mc_catch): New function.
(throw_exception): Adjust.
* common/common-exceptions.h (exceptions_state_mc_init): Remove
all parameters.
(exceptions_state_mc_catch): Declare.
(TRY_CATCH): Rename to ...
(TRY): ... this. Remove EXCEPTION and MASK parameters.
(CATCH, END_CATCH): New.
All callers adjusted.
gdb/gdbserver/ChangeLog:
2015-03-07 Pedro Alves <palves@redhat.com>
Adjust all callers of TRY_CATCH to use TRY/CATCH/END_CATCH
instead.
150 lines
4.5 KiB
C
150 lines
4.5 KiB
C
/* Handling of inferior events for the event loop for GDB, the GNU debugger.
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Copyright (C) 1999-2015 Free Software Foundation, Inc.
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Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "inferior.h"
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#include "infrun.h"
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#include "target.h" /* For enum inferior_event_type. */
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#include "event-loop.h"
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#include "event-top.h"
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#include "inf-loop.h"
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#include "remote.h"
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#include "language.h"
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#include "gdbthread.h"
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#include "continuations.h"
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#include "interps.h"
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#include "top.h"
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#include "observer.h"
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/* General function to handle events in the inferior. So far it just
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takes care of detecting errors reported by select() or poll(),
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otherwise it assumes that all is OK, and goes on reading data from
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the fd. This however may not always be what we want to do. */
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void
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inferior_event_handler (enum inferior_event_type event_type,
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gdb_client_data client_data)
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{
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struct cleanup *cleanup_if_error = make_bpstat_clear_actions_cleanup ();
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switch (event_type)
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{
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case INF_REG_EVENT:
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/* Catch errors for now, until the inner layers of
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fetch_inferior_event (i.e. readchar) can return meaningful
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error status. If an error occurs while getting an event from
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the target, just cancel the current command. */
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{
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TRY
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{
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fetch_inferior_event (client_data);
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}
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CATCH (ex, RETURN_MASK_ALL)
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{
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bpstat_clear_actions ();
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do_all_intermediate_continuations (1);
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do_all_continuations (1);
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throw_exception (ex);
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}
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END_CATCH
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}
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break;
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case INF_EXEC_COMPLETE:
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if (!non_stop)
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{
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/* Unregister the inferior from the event loop. This is done
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so that when the inferior is not running we don't get
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distracted by spurious inferior output. */
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if (target_has_execution)
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target_async (NULL, 0);
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}
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/* Do all continuations associated with the whole inferior (not
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a particular thread). */
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if (!ptid_equal (inferior_ptid, null_ptid))
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do_all_inferior_continuations (0);
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/* If we were doing a multi-step (eg: step n, next n), but it
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got interrupted by a breakpoint, still do the pending
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continuations. The continuation itself is responsible for
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distinguishing the cases. The continuations are allowed to
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touch the inferior memory, e.g. to remove breakpoints, so run
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them before running breakpoint commands, which may resume the
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target. */
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if (non_stop
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&& target_has_execution
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&& !ptid_equal (inferior_ptid, null_ptid))
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do_all_intermediate_continuations_thread (inferior_thread (), 0);
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else
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do_all_intermediate_continuations (0);
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/* Always finish the previous command before running any
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breakpoint commands. Any stop cancels the previous command.
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E.g. a "finish" or "step-n" command interrupted by an
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unrelated breakpoint is canceled. */
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if (non_stop
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&& target_has_execution
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&& !ptid_equal (inferior_ptid, null_ptid))
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do_all_continuations_thread (inferior_thread (), 0);
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else
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do_all_continuations (0);
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/* When running a command list (from a user command, say), these
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are only run when the command list is all done. */
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if (interpreter_async)
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{
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check_frame_language_change ();
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/* Don't propagate breakpoint commands errors. Either we're
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stopping or some command resumes the inferior. The user will
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be informed. */
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TRY
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{
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bpstat_do_actions ();
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}
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CATCH (e, RETURN_MASK_ALL)
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{
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exception_print (gdb_stderr, e);
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}
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END_CATCH
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}
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break;
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case INF_EXEC_CONTINUE:
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/* Is there anything left to do for the command issued to
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complete? */
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if (non_stop)
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do_all_intermediate_continuations_thread (inferior_thread (), 0);
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else
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do_all_intermediate_continuations (0);
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break;
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case INF_TIMER:
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default:
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printf_unfiltered (_("Event type not recognized.\n"));
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break;
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}
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discard_cleanups (cleanup_if_error);
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}
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