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469 lines
13 KiB
C
469 lines
13 KiB
C
/* GDB/Scheme support for safe calls into the Guile interpreter.
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Copyright (C) 2014-2023 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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/* See README file in this directory for implementation notes, coding
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conventions, et.al. */
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#include "defs.h"
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#include "filenames.h"
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#include "guile-internal.h"
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#include "gdbsupport/pathstuff.h"
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/* Struct to marshall args to scscm_safe_call_body. */
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struct c_data
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{
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const char *(*func) (void *);
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void *data;
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/* An error message or NULL for success. */
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const char *result;
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};
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/* Struct to marshall args through gdbscm_with_catch. */
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struct with_catch_data
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{
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scm_t_catch_body func;
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void *data;
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scm_t_catch_handler unwind_handler;
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scm_t_catch_handler pre_unwind_handler;
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/* If EXCP_MATCHER is non-NULL, it is an excp_matcher_func function.
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If the exception is recognized by it, the exception is recorded as is,
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without wrapping it in gdb:with-stack. */
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excp_matcher_func *excp_matcher;
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SCM stack;
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SCM catch_result;
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};
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/* The "body" argument to scm_i_with_continuation_barrier.
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Invoke the user-supplied function. */
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static SCM
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scscm_safe_call_body (void *d)
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{
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struct c_data *data = (struct c_data *) d;
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data->result = data->func (data->data);
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return SCM_UNSPECIFIED;
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}
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/* A "pre-unwind handler" to scm_c_catch that prints the exception
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according to "set guile print-stack". */
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static SCM
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scscm_printing_pre_unwind_handler (void *data, SCM key, SCM args)
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{
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SCM stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2)));
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gdbscm_print_exception_with_stack (SCM_BOOL_F, stack, key, args);
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return SCM_UNSPECIFIED;
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}
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/* A no-op unwind handler. */
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static SCM
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scscm_nop_unwind_handler (void *data, SCM key, SCM args)
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{
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return SCM_UNSPECIFIED;
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}
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/* The "pre-unwind handler" to scm_c_catch that records the exception
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for possible later printing. We do this in the pre-unwind handler because
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we want the stack to include point where the exception occurred.
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If DATA is non-NULL, it is an excp_matcher_func function.
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If the exception is recognized by it, the exception is recorded as is,
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without wrapping it in gdb:with-stack. */
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static SCM
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scscm_recording_pre_unwind_handler (void *datap, SCM key, SCM args)
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{
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struct with_catch_data *data = (struct with_catch_data *) datap;
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excp_matcher_func *matcher = data->excp_matcher;
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if (matcher != NULL && matcher (key))
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return SCM_UNSPECIFIED;
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/* There's no need to record the whole stack if we're not going to print it.
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However, convention is to still print the stack frame in which the
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exception occurred, even if we're not going to print a full backtrace.
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For now, keep it simple. */
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data->stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2)));
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/* IWBN if we could return the <gdb:exception> here and skip the unwind
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handler, but it doesn't work that way. If we want to return a
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<gdb:exception> object from the catch it needs to come from the unwind
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handler. So what we do is save the stack for later use by the unwind
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handler. */
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return SCM_UNSPECIFIED;
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}
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/* Part two of the recording unwind handler.
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Here we take the stack saved from the pre-unwind handler and create
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the <gdb:exception> object. */
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static SCM
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scscm_recording_unwind_handler (void *datap, SCM key, SCM args)
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{
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struct with_catch_data *data = (struct with_catch_data *) datap;
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/* We need to record the stack in the exception since we're about to
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throw and lose the location that got the exception. We do this by
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wrapping the exception + stack in a new exception. */
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if (gdbscm_is_true (data->stack))
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return gdbscm_make_exception_with_stack (key, args, data->stack);
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return gdbscm_make_exception (key, args);
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}
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/* Ugh. :-(
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Guile doesn't export scm_i_with_continuation_barrier which is exactly
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what we need. To cope, have our own wrapper around scm_c_catch and
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pass this as the "body" argument to scm_c_with_continuation_barrier.
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Darn darn darn. */
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static void *
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gdbscm_with_catch (void *data)
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{
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struct with_catch_data *d = (struct with_catch_data *) data;
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d->catch_result
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= scm_c_catch (SCM_BOOL_T,
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d->func, d->data,
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d->unwind_handler, d,
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d->pre_unwind_handler, d);
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#if HAVE_GUILE_MANUAL_FINALIZATION
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scm_run_finalizers ();
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#endif
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return NULL;
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}
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/* A wrapper around scm_with_guile that prints backtraces and exceptions
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according to "set guile print-stack".
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The result if NULL if no exception occurred, otherwise it is a statically
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allocated error message (caller must *not* free). */
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const char *
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gdbscm_with_guile (const char *(*func) (void *), void *data)
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{
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struct c_data c_data;
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struct with_catch_data catch_data;
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c_data.func = func;
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c_data.data = data;
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/* Set this now in case an exception is thrown. */
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c_data.result = _("Error while executing Scheme code.");
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catch_data.func = scscm_safe_call_body;
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catch_data.data = &c_data;
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catch_data.unwind_handler = scscm_nop_unwind_handler;
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catch_data.pre_unwind_handler = scscm_printing_pre_unwind_handler;
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catch_data.excp_matcher = NULL;
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catch_data.stack = SCM_BOOL_F;
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catch_data.catch_result = SCM_UNSPECIFIED;
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scm_with_guile (gdbscm_with_catch, &catch_data);
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return c_data.result;
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}
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/* Another wrapper of scm_with_guile for use by the safe call/apply routines
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in this file, as well as for general purpose calling other functions safely.
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For these we want to record the exception, but leave the possible printing
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of it to later. */
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SCM
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gdbscm_call_guile (SCM (*func) (void *), void *data,
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excp_matcher_func *ok_excps)
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{
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struct with_catch_data catch_data;
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catch_data.func = func;
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catch_data.data = data;
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catch_data.unwind_handler = scscm_recording_unwind_handler;
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catch_data.pre_unwind_handler = scscm_recording_pre_unwind_handler;
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catch_data.excp_matcher = ok_excps;
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catch_data.stack = SCM_BOOL_F;
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catch_data.catch_result = SCM_UNSPECIFIED;
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#if 0
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scm_c_with_continuation_barrier (gdbscm_with_catch, &catch_data);
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#else
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scm_with_guile (gdbscm_with_catch, &catch_data);
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#endif
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return catch_data.catch_result;
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}
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/* Utilities to safely call Scheme code, catching all exceptions, and
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preventing continuation capture.
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The result is the result of calling the function, or if an exception occurs
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then the result is a <gdb:exception> smob, which can be tested for with
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gdbscm_is_exception. */
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/* Helper for gdbscm_safe_call_0. */
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static SCM
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scscm_call_0_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_call_0 (args[0]);
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}
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SCM
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gdbscm_safe_call_0 (SCM proc, excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc };
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return gdbscm_call_guile (scscm_call_0_body, args, ok_excps);
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}
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/* Helper for gdbscm_safe_call_1. */
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static SCM
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scscm_call_1_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_call_1 (args[0], args[1]);
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}
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SCM
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gdbscm_safe_call_1 (SCM proc, SCM arg0, excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc, arg0 };
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return gdbscm_call_guile (scscm_call_1_body, args, ok_excps);
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}
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/* Helper for gdbscm_safe_call_2. */
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static SCM
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scscm_call_2_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_call_2 (args[0], args[1], args[2]);
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}
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SCM
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gdbscm_safe_call_2 (SCM proc, SCM arg0, SCM arg1, excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc, arg0, arg1 };
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return gdbscm_call_guile (scscm_call_2_body, args, ok_excps);
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}
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/* Helper for gdbscm_safe_call_3. */
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static SCM
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scscm_call_3_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_call_3 (args[0], args[1], args[2], args[3]);
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}
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SCM
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gdbscm_safe_call_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3,
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excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc, arg1, arg2, arg3 };
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return gdbscm_call_guile (scscm_call_3_body, args, ok_excps);
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}
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/* Helper for gdbscm_safe_call_4. */
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static SCM
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scscm_call_4_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_call_4 (args[0], args[1], args[2], args[3], args[4]);
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}
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SCM
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gdbscm_safe_call_4 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM arg4,
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excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc, arg1, arg2, arg3, arg4 };
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return gdbscm_call_guile (scscm_call_4_body, args, ok_excps);
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}
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/* Helper for gdbscm_safe_apply_1. */
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static SCM
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scscm_apply_1_body (void *argsp)
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{
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SCM *args = (SCM *) argsp;
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return scm_apply_1 (args[0], args[1], args[2]);
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}
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SCM
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gdbscm_safe_apply_1 (SCM proc, SCM arg0, SCM rest, excp_matcher_func *ok_excps)
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{
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SCM args[] = { proc, arg0, rest };
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return gdbscm_call_guile (scscm_apply_1_body, args, ok_excps);
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}
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/* Utilities to call Scheme code, not catching exceptions, and
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not preventing continuation capture.
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The result is the result of calling the function.
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If an exception occurs then Guile is left to handle the exception,
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unwinding the stack as appropriate.
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USE THESE WITH CARE.
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Typically these are called from functions that implement Scheme procedures,
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and we don't want to catch the exception; otherwise it will get printed
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twice: once when first caught and once if it ends up being rethrown and the
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rethrow reaches the top repl, which will confuse the user.
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While these calls just pass the call off to the corresponding Guile
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procedure, all such calls are routed through these ones to:
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a) provide a place to put hooks or whatnot in if we need to,
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b) add "unsafe" to the name to alert the reader. */
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SCM
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gdbscm_unsafe_call_1 (SCM proc, SCM arg0)
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{
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return scm_call_1 (proc, arg0);
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}
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/* Utilities for safely evaluating a Scheme expression string. */
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struct eval_scheme_string_data
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{
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const char *string;
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int display_result;
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};
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/* Wrapper to eval a C string in the Guile interpreter.
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This is passed to gdbscm_with_guile. */
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static const char *
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scscm_eval_scheme_string (void *datap)
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{
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struct eval_scheme_string_data *data
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= (struct eval_scheme_string_data *) datap;
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SCM result = scm_c_eval_string (data->string);
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if (data->display_result && !scm_is_eq (result, SCM_UNSPECIFIED))
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{
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SCM port = scm_current_output_port ();
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scm_write (result, port);
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scm_newline (port);
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}
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/* If we get here the eval succeeded. */
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return NULL;
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}
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/* Evaluate EXPR in the Guile interpreter, catching all exceptions
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and preventing continuation capture.
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The result is NULL if no exception occurred. Otherwise, the exception is
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printed according to "set guile print-stack" and the result is an error
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message. */
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gdb::unique_xmalloc_ptr<char>
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gdbscm_safe_eval_string (const char *string, int display_result)
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{
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struct eval_scheme_string_data data = { string, display_result };
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const char *result;
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result = gdbscm_with_guile (scscm_eval_scheme_string, (void *) &data);
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if (result != NULL)
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return make_unique_xstrdup (result);
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return NULL;
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}
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/* Utilities for safely loading Scheme scripts. */
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/* Helper function for gdbscm_safe_source_scheme_script. */
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static const char *
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scscm_source_scheme_script (void *data)
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{
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const char *filename = (const char *) data;
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/* The Guile docs don't specify what the result is.
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Maybe it's SCM_UNSPECIFIED, but the docs should specify that. :-) */
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scm_c_primitive_load_path (filename);
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/* If we get here the load succeeded. */
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return NULL;
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}
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/* Try to load a script, catching all exceptions,
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and preventing continuation capture.
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The result is NULL if the load succeeded. Otherwise, the exception is
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printed according to "set guile print-stack" and the result is an error
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message allocated with malloc, caller must free. */
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gdb::unique_xmalloc_ptr<char>
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gdbscm_safe_source_script (const char *filename)
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{
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/* scm_c_primitive_load_path only looks in %load-path for files with
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relative paths. An alternative could be to temporarily add "." to
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%load-path, but we don't want %load-path to be searched. At least not
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by default. This function is invoked by the "source" GDB command which
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already has its own path search support. */
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gdb::unique_xmalloc_ptr<char> abs_filename;
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const char *result;
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if (!IS_ABSOLUTE_PATH (filename))
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{
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abs_filename = gdb_realpath (filename);
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filename = abs_filename.get ();
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}
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result = gdbscm_with_guile (scscm_source_scheme_script,
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(void *) filename);
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if (result != NULL)
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return make_unique_xstrdup (result);
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return NULL;
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}
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/* Utility for entering an interactive Guile repl. */
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void
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gdbscm_enter_repl (void)
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{
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/* It's unfortunate to have to resort to something like this, but
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scm_shell doesn't return. :-( I found this code on guile-user@. */
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gdbscm_safe_call_1 (scm_c_public_ref ("system repl repl", "start-repl"),
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scm_from_latin1_symbol ("scheme"), NULL);
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}
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