| /* GDB/Scheme support for safe calls into the Guile interpreter. |
| |
| Copyright (C) 2014-2021 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/>. */ |
| |
| /* See README file in this directory for implementation notes, coding |
| conventions, et.al. */ |
| |
| #include "defs.h" |
| #include "filenames.h" |
| #include "guile-internal.h" |
| #include "gdbsupport/pathstuff.h" |
| |
| /* Struct to marshall args to scscm_safe_call_body. */ |
| |
| struct c_data |
| { |
| const char *(*func) (void *); |
| void *data; |
| /* An error message or NULL for success. */ |
| const char *result; |
| }; |
| |
| /* Struct to marshall args through gdbscm_with_catch. */ |
| |
| struct with_catch_data |
| { |
| scm_t_catch_body func; |
| void *data; |
| scm_t_catch_handler unwind_handler; |
| scm_t_catch_handler pre_unwind_handler; |
| |
| /* If EXCP_MATCHER is non-NULL, it is an excp_matcher_func function. |
| If the exception is recognized by it, the exception is recorded as is, |
| without wrapping it in gdb:with-stack. */ |
| excp_matcher_func *excp_matcher; |
| |
| SCM stack; |
| SCM catch_result; |
| }; |
| |
| /* The "body" argument to scm_i_with_continuation_barrier. |
| Invoke the user-supplied function. */ |
| |
| static SCM |
| scscm_safe_call_body (void *d) |
| { |
| struct c_data *data = (struct c_data *) d; |
| |
| data->result = data->func (data->data); |
| |
| return SCM_UNSPECIFIED; |
| } |
| |
| /* A "pre-unwind handler" to scm_c_catch that prints the exception |
| according to "set guile print-stack". */ |
| |
| static SCM |
| scscm_printing_pre_unwind_handler (void *data, SCM key, SCM args) |
| { |
| SCM stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); |
| |
| gdbscm_print_exception_with_stack (SCM_BOOL_F, stack, key, args); |
| |
| return SCM_UNSPECIFIED; |
| } |
| |
| /* A no-op unwind handler. */ |
| |
| static SCM |
| scscm_nop_unwind_handler (void *data, SCM key, SCM args) |
| { |
| return SCM_UNSPECIFIED; |
| } |
| |
| /* The "pre-unwind handler" to scm_c_catch that records the exception |
| for possible later printing. We do this in the pre-unwind handler because |
| we want the stack to include point where the exception occurred. |
| |
| If DATA is non-NULL, it is an excp_matcher_func function. |
| If the exception is recognized by it, the exception is recorded as is, |
| without wrapping it in gdb:with-stack. */ |
| |
| static SCM |
| scscm_recording_pre_unwind_handler (void *datap, SCM key, SCM args) |
| { |
| struct with_catch_data *data = (struct with_catch_data *) datap; |
| excp_matcher_func *matcher = data->excp_matcher; |
| |
| if (matcher != NULL && matcher (key)) |
| return SCM_UNSPECIFIED; |
| |
| /* There's no need to record the whole stack if we're not going to print it. |
| However, convention is to still print the stack frame in which the |
| exception occurred, even if we're not going to print a full backtrace. |
| For now, keep it simple. */ |
| |
| data->stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); |
| |
| /* IWBN if we could return the <gdb:exception> here and skip the unwind |
| handler, but it doesn't work that way. If we want to return a |
| <gdb:exception> object from the catch it needs to come from the unwind |
| handler. So what we do is save the stack for later use by the unwind |
| handler. */ |
| |
| return SCM_UNSPECIFIED; |
| } |
| |
| /* Part two of the recording unwind handler. |
| Here we take the stack saved from the pre-unwind handler and create |
| the <gdb:exception> object. */ |
| |
| static SCM |
| scscm_recording_unwind_handler (void *datap, SCM key, SCM args) |
| { |
| struct with_catch_data *data = (struct with_catch_data *) datap; |
| |
| /* We need to record the stack in the exception since we're about to |
| throw and lose the location that got the exception. We do this by |
| wrapping the exception + stack in a new exception. */ |
| |
| if (gdbscm_is_true (data->stack)) |
| return gdbscm_make_exception_with_stack (key, args, data->stack); |
| |
| return gdbscm_make_exception (key, args); |
| } |
| |
| /* Ugh. :-( |
| Guile doesn't export scm_i_with_continuation_barrier which is exactly |
| what we need. To cope, have our own wrapper around scm_c_catch and |
| pass this as the "body" argument to scm_c_with_continuation_barrier. |
| Darn darn darn. */ |
| |
| static void * |
| gdbscm_with_catch (void *data) |
| { |
| struct with_catch_data *d = (struct with_catch_data *) data; |
| |
| d->catch_result |
| = scm_c_catch (SCM_BOOL_T, |
| d->func, d->data, |
| d->unwind_handler, d, |
| d->pre_unwind_handler, d); |
| |
| #if HAVE_GUILE_MANUAL_FINALIZATION |
| scm_run_finalizers (); |
| #endif |
| |
| return NULL; |
| } |
| |
| /* A wrapper around scm_with_guile that prints backtraces and exceptions |
| according to "set guile print-stack". |
| The result if NULL if no exception occurred, otherwise it is a statically |
| allocated error message (caller must *not* free). */ |
| |
| const char * |
| gdbscm_with_guile (const char *(*func) (void *), void *data) |
| { |
| struct c_data c_data; |
| struct with_catch_data catch_data; |
| |
| c_data.func = func; |
| c_data.data = data; |
| /* Set this now in case an exception is thrown. */ |
| c_data.result = _("Error while executing Scheme code."); |
| |
| catch_data.func = scscm_safe_call_body; |
| catch_data.data = &c_data; |
| catch_data.unwind_handler = scscm_nop_unwind_handler; |
| catch_data.pre_unwind_handler = scscm_printing_pre_unwind_handler; |
| catch_data.excp_matcher = NULL; |
| catch_data.stack = SCM_BOOL_F; |
| catch_data.catch_result = SCM_UNSPECIFIED; |
| |
| scm_with_guile (gdbscm_with_catch, &catch_data); |
| |
| return c_data.result; |
| } |
| |
| /* Another wrapper of scm_with_guile for use by the safe call/apply routines |
| in this file, as well as for general purpose calling other functions safely. |
| For these we want to record the exception, but leave the possible printing |
| of it to later. */ |
| |
| SCM |
| gdbscm_call_guile (SCM (*func) (void *), void *data, |
| excp_matcher_func *ok_excps) |
| { |
| struct with_catch_data catch_data; |
| |
| catch_data.func = func; |
| catch_data.data = data; |
| catch_data.unwind_handler = scscm_recording_unwind_handler; |
| catch_data.pre_unwind_handler = scscm_recording_pre_unwind_handler; |
| catch_data.excp_matcher = ok_excps; |
| catch_data.stack = SCM_BOOL_F; |
| catch_data.catch_result = SCM_UNSPECIFIED; |
| |
| #if 0 |
| scm_c_with_continuation_barrier (gdbscm_with_catch, &catch_data); |
| #else |
| scm_with_guile (gdbscm_with_catch, &catch_data); |
| #endif |
| |
| return catch_data.catch_result; |
| } |
| |
| /* Utilities to safely call Scheme code, catching all exceptions, and |
| preventing continuation capture. |
| The result is the result of calling the function, or if an exception occurs |
| then the result is a <gdb:exception> smob, which can be tested for with |
| gdbscm_is_exception. */ |
| |
| /* Helper for gdbscm_safe_call_0. */ |
| |
| static SCM |
| scscm_call_0_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_call_0 (args[0]); |
| } |
| |
| SCM |
| gdbscm_safe_call_0 (SCM proc, excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc }; |
| |
| return gdbscm_call_guile (scscm_call_0_body, args, ok_excps); |
| } |
| |
| /* Helper for gdbscm_safe_call_1. */ |
| |
| static SCM |
| scscm_call_1_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_call_1 (args[0], args[1]); |
| } |
| |
| SCM |
| gdbscm_safe_call_1 (SCM proc, SCM arg0, excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc, arg0 }; |
| |
| return gdbscm_call_guile (scscm_call_1_body, args, ok_excps); |
| } |
| |
| /* Helper for gdbscm_safe_call_2. */ |
| |
| static SCM |
| scscm_call_2_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_call_2 (args[0], args[1], args[2]); |
| } |
| |
| SCM |
| gdbscm_safe_call_2 (SCM proc, SCM arg0, SCM arg1, excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc, arg0, arg1 }; |
| |
| return gdbscm_call_guile (scscm_call_2_body, args, ok_excps); |
| } |
| |
| /* Helper for gdbscm_safe_call_3. */ |
| |
| static SCM |
| scscm_call_3_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_call_3 (args[0], args[1], args[2], args[3]); |
| } |
| |
| SCM |
| gdbscm_safe_call_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3, |
| excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc, arg1, arg2, arg3 }; |
| |
| return gdbscm_call_guile (scscm_call_3_body, args, ok_excps); |
| } |
| |
| /* Helper for gdbscm_safe_call_4. */ |
| |
| static SCM |
| scscm_call_4_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_call_4 (args[0], args[1], args[2], args[3], args[4]); |
| } |
| |
| SCM |
| gdbscm_safe_call_4 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM arg4, |
| excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc, arg1, arg2, arg3, arg4 }; |
| |
| return gdbscm_call_guile (scscm_call_4_body, args, ok_excps); |
| } |
| |
| /* Helper for gdbscm_safe_apply_1. */ |
| |
| static SCM |
| scscm_apply_1_body (void *argsp) |
| { |
| SCM *args = (SCM *) argsp; |
| |
| return scm_apply_1 (args[0], args[1], args[2]); |
| } |
| |
| SCM |
| gdbscm_safe_apply_1 (SCM proc, SCM arg0, SCM rest, excp_matcher_func *ok_excps) |
| { |
| SCM args[] = { proc, arg0, rest }; |
| |
| return gdbscm_call_guile (scscm_apply_1_body, args, ok_excps); |
| } |
| |
| /* Utilities to call Scheme code, not catching exceptions, and |
| not preventing continuation capture. |
| The result is the result of calling the function. |
| If an exception occurs then Guile is left to handle the exception, |
| unwinding the stack as appropriate. |
| |
| USE THESE WITH CARE. |
| Typically these are called from functions that implement Scheme procedures, |
| and we don't want to catch the exception; otherwise it will get printed |
| twice: once when first caught and once if it ends up being rethrown and the |
| rethrow reaches the top repl, which will confuse the user. |
| |
| While these calls just pass the call off to the corresponding Guile |
| procedure, all such calls are routed through these ones to: |
| a) provide a place to put hooks or whatnot in if we need to, |
| b) add "unsafe" to the name to alert the reader. */ |
| |
| SCM |
| gdbscm_unsafe_call_1 (SCM proc, SCM arg0) |
| { |
| return scm_call_1 (proc, arg0); |
| } |
| |
| /* Utilities for safely evaluating a Scheme expression string. */ |
| |
| struct eval_scheme_string_data |
| { |
| const char *string; |
| int display_result; |
| }; |
| |
| /* Wrapper to eval a C string in the Guile interpreter. |
| This is passed to gdbscm_with_guile. */ |
| |
| static const char * |
| scscm_eval_scheme_string (void *datap) |
| { |
| struct eval_scheme_string_data *data |
| = (struct eval_scheme_string_data *) datap; |
| SCM result = scm_c_eval_string (data->string); |
| |
| if (data->display_result && !scm_is_eq (result, SCM_UNSPECIFIED)) |
| { |
| SCM port = scm_current_output_port (); |
| |
| scm_write (result, port); |
| scm_newline (port); |
| } |
| |
| /* If we get here the eval succeeded. */ |
| return NULL; |
| } |
| |
| /* Evaluate EXPR in the Guile interpreter, catching all exceptions |
| and preventing continuation capture. |
| The result is NULL if no exception occurred. Otherwise, the exception is |
| printed according to "set guile print-stack" and the result is an error |
| message. */ |
| |
| gdb::unique_xmalloc_ptr<char> |
| gdbscm_safe_eval_string (const char *string, int display_result) |
| { |
| struct eval_scheme_string_data data = { string, display_result }; |
| const char *result; |
| |
| result = gdbscm_with_guile (scscm_eval_scheme_string, (void *) &data); |
| |
| if (result != NULL) |
| return make_unique_xstrdup (result); |
| return NULL; |
| } |
| |
| /* Utilities for safely loading Scheme scripts. */ |
| |
| /* Helper function for gdbscm_safe_source_scheme_script. */ |
| |
| static const char * |
| scscm_source_scheme_script (void *data) |
| { |
| const char *filename = (const char *) data; |
| |
| /* The Guile docs don't specify what the result is. |
| Maybe it's SCM_UNSPECIFIED, but the docs should specify that. :-) */ |
| scm_c_primitive_load_path (filename); |
| |
| /* If we get here the load succeeded. */ |
| return NULL; |
| } |
| |
| /* Try to load a script, catching all exceptions, |
| and preventing continuation capture. |
| The result is NULL if the load succeeded. Otherwise, the exception is |
| printed according to "set guile print-stack" and the result is an error |
| message allocated with malloc, caller must free. */ |
| |
| gdb::unique_xmalloc_ptr<char> |
| gdbscm_safe_source_script (const char *filename) |
| { |
| /* scm_c_primitive_load_path only looks in %load-path for files with |
| relative paths. An alternative could be to temporarily add "." to |
| %load-path, but we don't want %load-path to be searched. At least not |
| by default. This function is invoked by the "source" GDB command which |
| already has its own path search support. */ |
| gdb::unique_xmalloc_ptr<char> abs_filename; |
| const char *result; |
| |
| if (!IS_ABSOLUTE_PATH (filename)) |
| { |
| abs_filename = gdb_realpath (filename); |
| filename = abs_filename.get (); |
| } |
| |
| result = gdbscm_with_guile (scscm_source_scheme_script, |
| (void *) filename); |
| |
| if (result != NULL) |
| return make_unique_xstrdup (result); |
| return NULL; |
| } |
| |
| /* Utility for entering an interactive Guile repl. */ |
| |
| void |
| gdbscm_enter_repl (void) |
| { |
| /* It's unfortunate to have to resort to something like this, but |
| scm_shell doesn't return. :-( I found this code on guile-user@. */ |
| gdbscm_safe_call_1 (scm_c_public_ref ("system repl repl", "start-repl"), |
| scm_from_latin1_symbol ("scheme"), NULL); |
| } |