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/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
Copyright (C) 1986-2020 Free Software Foundation, Inc.
This file is part of GDB.
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/>. */
#include "common-defs.h"
#include "common-exceptions.h"
#include <forward_list>
/* Possible catcher states. */
enum catcher_state {
/* Initial state, a new catcher has just been created. */
CATCHER_CREATED,
/* The catch code is running. */
CATCHER_RUNNING,
CATCHER_RUNNING_1,
/* The catch code threw an exception. */
CATCHER_ABORTING
};
/* Possible catcher actions. */
enum catcher_action {
CATCH_ITER,
CATCH_ITER_1,
CATCH_THROWING
};
struct catcher
{
enum catcher_state state = CATCHER_CREATED;
/* Jump buffer pointing back at the exception handler. */
jmp_buf buf;
/* Status buffer belonging to the exception handler. */
struct gdb_exception exception;
};
/* Where to go for throw_exception(). */
static std::forward_list<struct catcher> catchers;
jmp_buf *
exceptions_state_mc_init ()
{
catchers.emplace_front ();
return &catchers.front ().buf;
}
/* Catcher state machine. Returns non-zero if the m/c should be run
again, zero if it should abort. */
static int
exceptions_state_mc (enum catcher_action action)
{
switch (catchers.front ().state)
{
case CATCHER_CREATED:
switch (action)
{
case CATCH_ITER:
/* Allow the code to run the catcher. */
catchers.front ().state = CATCHER_RUNNING;
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad state"));
}
case CATCHER_RUNNING:
switch (action)
{
case CATCH_ITER:
/* No error/quit has occured. */
return 0;
case CATCH_ITER_1:
catchers.front ().state = CATCHER_RUNNING_1;
return 1;
case CATCH_THROWING:
catchers.front ().state = CATCHER_ABORTING;
/* See also throw_exception. */
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
case CATCHER_RUNNING_1:
switch (action)
{
case CATCH_ITER:
/* The did a "break" from the inner while loop. */
return 0;
case CATCH_ITER_1:
catchers.front ().state = CATCHER_RUNNING;
return 0;
case CATCH_THROWING:
catchers.front ().state = CATCHER_ABORTING;
/* See also throw_exception. */
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
case CATCHER_ABORTING:
switch (action)
{
case CATCH_ITER:
{
/* Exit normally if this catcher can handle this
exception. The caller analyses the func return
values. */
return 0;
}
default:
internal_error (__FILE__, __LINE__, _("bad state"));
}
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
}
int
exceptions_state_mc_catch (struct gdb_exception *exception,
int mask)
{
*exception = std::move (catchers.front ().exception);
catchers.pop_front ();
if (exception->reason < 0)
{
if (mask & RETURN_MASK (exception->reason))
{
/* Exit normally and let the caller handle the
exception. */
return 1;
}
/* The caller didn't request that the event be caught, relay the
event to the next exception_catch/CATCH_SJLJ. */
throw_exception_sjlj (*exception);
}
/* No exception was thrown. */
return 0;
}
int
exceptions_state_mc_action_iter (void)
{
return exceptions_state_mc (CATCH_ITER);
}
int
exceptions_state_mc_action_iter_1 (void)
{
return exceptions_state_mc (CATCH_ITER_1);
}
/* Return EXCEPTION to the nearest containing CATCH_SJLJ block. */
void
throw_exception_sjlj (const struct gdb_exception &exception)
{
/* Jump to the nearest CATCH_SJLJ block, communicating REASON to
that call via setjmp's return value. Note that REASON can't be
zero, by definition in common-exceptions.h. */
exceptions_state_mc (CATCH_THROWING);
enum return_reason reason = exception.reason;
catchers.front ().exception = exception;
longjmp (catchers.front ().buf, reason);
}
/* Implementation of throw_exception that uses C++ try/catch. */
void
throw_exception (gdb_exception &&exception)
{
if (exception.reason == RETURN_QUIT)
throw gdb_exception_quit (std::move (exception));
else if (exception.reason == RETURN_ERROR)
throw gdb_exception_error (std::move (exception));
else
gdb_assert_not_reached ("invalid return reason");
}
static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0)
throw_it (enum return_reason reason, enum errors error, const char *fmt,
va_list ap)
{
if (reason == RETURN_QUIT)
throw gdb_exception_quit (fmt, ap);
else if (reason == RETURN_ERROR)
throw gdb_exception_error (error, fmt, ap);
else
gdb_assert_not_reached ("invalid return reason");
}
void
throw_verror (enum errors error, const char *fmt, va_list ap)
{
throw_it (RETURN_ERROR, error, fmt, ap);
}
void
throw_vquit (const char *fmt, va_list ap)
{
throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap);
}
void
throw_error (enum errors error, const char *fmt, ...)
{
va_list args;
va_start (args, fmt);
throw_verror (error, fmt, args);
va_end (args);
}
void
throw_quit (const char *fmt, ...)
{
va_list args;
va_start (args, fmt);
throw_vquit (fmt, args);
va_end (args);
}
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