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.
112 lines
3.2 KiB
C
112 lines
3.2 KiB
C
/* Readline support for Python.
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Copyright (C) 2012-2015 Free Software Foundation, Inc.
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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 "python-internal.h"
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#include "top.h"
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#include "cli/cli-utils.h"
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/* Readline function suitable for PyOS_ReadlineFunctionPointer, which
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is used for Python's interactive parser and raw_input. In both
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cases, sys_stdin and sys_stdout are always stdin and stdout
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respectively, as far as I can tell; they are ignored and
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command_line_input is used instead. */
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static char *
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gdbpy_readline_wrapper (FILE *sys_stdin, FILE *sys_stdout,
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#if PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 4
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const char *prompt)
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#else
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char *prompt)
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#endif
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{
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int n;
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char *p = NULL, *q;
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TRY
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{
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p = command_line_input (prompt, 0, "python");
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}
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/* Handle errors by raising Python exceptions. */
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CATCH (except, RETURN_MASK_ALL)
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{
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/* Detect user interrupt (Ctrl-C). */
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if (except.reason == RETURN_QUIT)
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return NULL;
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/* The thread state is nulled during gdbpy_readline_wrapper,
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with the original value saved in the following undocumented
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variable (see Python's Parser/myreadline.c and
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Modules/readline.c). */
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PyEval_RestoreThread (_PyOS_ReadlineTState);
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gdbpy_convert_exception (except);
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PyEval_SaveThread ();
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return NULL;
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}
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END_CATCH
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/* Detect EOF (Ctrl-D). */
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if (p == NULL)
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{
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q = PyMem_Malloc (1);
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if (q != NULL)
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q[0] = '\0';
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return q;
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}
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n = strlen (p);
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/* Copy the line to Python and return. */
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q = PyMem_Malloc (n + 2);
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if (q != NULL)
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{
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strncpy (q, p, n);
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q[n] = '\n';
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q[n + 1] = '\0';
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}
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return q;
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}
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/* Initialize Python readline support. */
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void
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gdbpy_initialize_gdb_readline (void)
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{
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/* Python's readline module conflicts with GDB's use of readline
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since readline is not reentrant. Ideally, a reentrant wrapper to
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GDB's readline should be implemented to replace Python's readline
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and prevent conflicts. For now, this file implements a
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sys.meta_path finder that simply fails to import the readline
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module. */
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if (PyRun_SimpleString ("\
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import sys\n\
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\n\
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class GdbRemoveReadlineFinder:\n\
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def find_module(self, fullname, path=None):\n\
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if fullname == 'readline' and path is None:\n\
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return self\n\
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return None\n\
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\n\
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def load_module(self, fullname):\n\
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raise ImportError('readline module disabled under GDB')\n\
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\n\
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sys.meta_path.append(GdbRemoveReadlineFinder())\n\
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") == 0)
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PyOS_ReadlineFunctionPointer = gdbpy_readline_wrapper;
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}
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