diff options
Diffstat (limited to 'libguile/throw.c')
-rw-r--r-- | libguile/throw.c | 530 |
1 files changed, 153 insertions, 377 deletions
diff --git a/libguile/throw.c b/libguile/throw.c index 055ad87d2..9c89c6511 100644 --- a/libguile/throw.c +++ b/libguile/throw.c @@ -23,17 +23,16 @@ # include <config.h> #endif -#include <alloca.h> #include <stdio.h> #include <unistdio.h> #include "backtrace.h" #include "boolean.h" -#include "control.h" #include "debug.h" -#include "deprecation.h" +#include "dynwind.h" #include "eq.h" #include "eval.h" +#include "exceptions.h" #include "fluids.h" #include "gsubr.h" #include "init.h" @@ -54,278 +53,13 @@ #include "throw.h" -/* Pleasantly enough, the guts of exception handling are defined in - Scheme, in terms of prompt, abort, and the %exception-handler fluid. - Check boot-9 for the definitions. - - Still, it's useful to be able to throw unwind-only exceptions from C, - for example so that we can recover from stack overflow. We also need - to have an implementation of catch and throw handy before boot time. - For that reason we have a parallel implementation of "catch" that - uses the same fluids here. Throws from C still call out to Scheme - though, so that pre-unwind handlers can be run. Getting the dynamic - environment right for pre-unwind handlers is tricky, and it's - important to have all of the implementation in one place. - - All of these function names and prototypes carry a fair bit of historical - baggage. */ - - static SCM throw_var; -static SCM exception_handler_fluid; - -static SCM -catch (SCM tag, SCM thunk, SCM handler, SCM pre_unwind_handler) -{ - SCM eh, prompt_tag; - SCM res; - scm_thread *t = SCM_I_CURRENT_THREAD; - scm_t_dynstack *dynstack = &t->dynstack; - scm_t_dynamic_state *dynamic_state = t->dynamic_state; - jmp_buf registers; - jmp_buf *prev_registers; - ptrdiff_t saved_stack_depth; - uint8_t *mra = NULL; - - if (!scm_is_eq (tag, SCM_BOOL_T) && !scm_is_symbol (tag)) - scm_wrong_type_arg ("catch", 1, tag); - - if (SCM_UNBNDP (handler)) - handler = SCM_BOOL_F; - else if (!scm_is_true (scm_procedure_p (handler))) - scm_wrong_type_arg ("catch", 3, handler); - - if (SCM_UNBNDP (pre_unwind_handler)) - pre_unwind_handler = SCM_BOOL_F; - else if (!scm_is_true (scm_procedure_p (pre_unwind_handler))) - scm_wrong_type_arg ("catch", 4, pre_unwind_handler); - - prompt_tag = scm_cons (SCM_INUM0, SCM_EOL); - - eh = scm_c_make_vector (3, SCM_BOOL_F); - scm_c_vector_set_x (eh, 0, tag); - scm_c_vector_set_x (eh, 1, prompt_tag); - scm_c_vector_set_x (eh, 2, pre_unwind_handler); - - prev_registers = t->vm.registers; - saved_stack_depth = t->vm.stack_top - t->vm.sp; - - /* Push the prompt and exception handler onto the dynamic stack. */ - scm_dynstack_push_prompt (dynstack, - SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY, - prompt_tag, - t->vm.stack_top - t->vm.fp, - saved_stack_depth, - t->vm.ip, - mra, - ®isters); - scm_dynstack_push_fluid (dynstack, exception_handler_fluid, eh, - dynamic_state); - - if (setjmp (registers)) - { - /* A non-local return. */ - SCM args; - - t->vm.registers = prev_registers; - scm_gc_after_nonlocal_exit (); - - /* FIXME: We know where the args will be on the stack; we could - avoid consing them. */ - args = scm_i_prompt_pop_abort_args_x (&t->vm, saved_stack_depth); - - /* Cdr past the continuation. */ - args = scm_cdr (args); - - return scm_apply_0 (handler, args); - } - - res = scm_call_0 (thunk); - - scm_dynstack_unwind_fluid (dynstack, dynamic_state); - scm_dynstack_pop (dynstack); - - return res; -} - -static void -default_exception_handler (SCM k, SCM args) -{ - static int error_printing_error = 0; - static int error_printing_fallback = 0; - - if (error_printing_fallback) - fprintf (stderr, "\nFailed to print exception.\n"); - else if (error_printing_error) - { - fprintf (stderr, "\nError while printing exception:\n"); - error_printing_fallback = 1; - fprintf (stderr, "Key: "); - scm_write (k, scm_current_error_port ()); - fprintf (stderr, ", args: "); - scm_write (args, scm_current_error_port ()); - scm_newline (scm_current_error_port ()); - } - else - { - fprintf (stderr, "Uncaught exception:\n"); - error_printing_error = 1; - scm_handle_by_message (NULL, k, args); - } - - /* Normally we don't get here, because scm_handle_by_message will - exit. */ - fprintf (stderr, "Aborting.\n"); - abort (); -} - -/* A version of scm_abort_to_prompt_star that avoids the need to cons - "tag" to "args", because we might be out of memory. */ -static void -abort_to_prompt (SCM prompt_tag, SCM tag, SCM args) -{ - SCM *tag_and_argv; - size_t i; - long n; - - n = scm_ilength (args) + 2; - tag_and_argv = alloca (sizeof (SCM)*n); - tag_and_argv[0] = prompt_tag; - tag_and_argv[1] = tag; - for (i = 2; i < n; i++, args = scm_cdr (args)) - tag_and_argv[i] = scm_car (args); - - scm_i_vm_emergency_abort (tag_and_argv, n); - /* Unreachable. */ - abort (); -} - -static SCM -throw_without_pre_unwind (SCM tag, SCM args) -{ - size_t depth = 0; - - /* This function is not only the boot implementation of "throw", it is - also called in response to resource allocation failures such as - stack-overflow or out-of-memory. For that reason we need to be - careful to avoid allocating memory. */ - while (1) - { - SCM eh, catch_key, prompt_tag; - - eh = scm_fluid_ref_star (exception_handler_fluid, - scm_from_size_t (depth++)); - if (scm_is_false (eh)) - break; - - catch_key = scm_c_vector_ref (eh, 0); - if (!scm_is_eq (catch_key, SCM_BOOL_T) && !scm_is_eq (catch_key, tag)) - continue; - - if (scm_is_true (scm_c_vector_ref (eh, 2))) - { - const char *key_chars; - - if (scm_i_is_narrow_symbol (tag)) - key_chars = scm_i_symbol_chars (tag); - else - key_chars = "(wide symbol)"; - - fprintf (stderr, "Warning: Unwind-only `%s' exception; " - "skipping pre-unwind handler.\n", key_chars); - } - - prompt_tag = scm_c_vector_ref (eh, 1); - if (scm_is_true (prompt_tag)) - abort_to_prompt (prompt_tag, tag, args); - } - - default_exception_handler (tag, args); - return SCM_UNSPECIFIED; -} - -SCM -scm_catch (SCM key, SCM thunk, SCM handler) -{ - return catch (key, thunk, handler, SCM_UNDEFINED); -} - -SCM -scm_catch_with_pre_unwind_handler (SCM key, SCM thunk, SCM handler, - SCM pre_unwind_handler) -{ - return catch (key, thunk, handler, pre_unwind_handler); -} - -SCM -scm_with_throw_handler (SCM key, SCM thunk, SCM handler) -{ - return catch (key, thunk, SCM_UNDEFINED, handler); -} - -SCM -scm_throw (SCM key, SCM args) -{ - scm_apply_1 (scm_variable_ref (throw_var), key, args); - /* Should not be reached. */ - abort (); -} -/* Now some support for C bodies and catch handlers */ - -static scm_t_bits tc16_catch_closure; - -enum { - CATCH_CLOSURE_BODY, - CATCH_CLOSURE_HANDLER -}; - -SCM -scm_i_make_catch_body_closure (scm_t_catch_body body, void *body_data) -{ - SCM ret; - SCM_NEWSMOB2 (ret, tc16_catch_closure, body, body_data); - SCM_SET_SMOB_FLAGS (ret, CATCH_CLOSURE_BODY); - return ret; -} - -SCM -scm_i_make_catch_handler_closure (scm_t_catch_handler handler, - void *handler_data) -{ - SCM ret; - SCM_NEWSMOB2 (ret, tc16_catch_closure, handler, handler_data); - SCM_SET_SMOB_FLAGS (ret, CATCH_CLOSURE_HANDLER); - return ret; -} - -static SCM -apply_catch_closure (SCM clo, SCM args) -{ - void *data = (void*)SCM_SMOB_DATA_2 (clo); - - switch (SCM_SMOB_FLAGS (clo)) - { - case CATCH_CLOSURE_BODY: - { - scm_t_catch_body body = (void*)SCM_SMOB_DATA (clo); - return body (data); - } - case CATCH_CLOSURE_HANDLER: - { - scm_t_catch_handler handler = (void*)SCM_SMOB_DATA (clo); - return handler (data, scm_car (args), scm_cdr (args)); - } - default: - abort (); - } -} - /* TAG is the catch tag. Typically, this is a symbol, but this function doesn't actually care about that. @@ -365,30 +99,79 @@ apply_catch_closure (SCM clo, SCM args) references anyway, this assures that any references in MUMBLE_DATA will be found. */ +struct scm_catch_data +{ + SCM tag; + scm_t_thunk body; + void *body_data; + scm_t_catch_handler handler; + void *handler_data; + scm_t_catch_handler pre_unwind_handler; + void *pre_unwind_handler_data; + SCM pre_unwind_running; +}; + +static SCM +catch_post_unwind_handler (void *data, SCM exn) +{ + struct scm_catch_data *catch_data = data; + return catch_data->handler (catch_data->handler_data, + scm_exception_kind (exn), + scm_exception_args (exn)); +} + +static SCM +catch_pre_unwind_handler (void *data, SCM exn) +{ + struct scm_catch_data *catch_data = data; + SCM kind = scm_exception_kind (exn); + SCM args = scm_exception_args (exn); + if ((scm_is_eq (catch_data->tag, SCM_BOOL_T) + || scm_is_eq (kind, catch_data->tag)) + && scm_is_false (scm_fluid_ref (catch_data->pre_unwind_running))) { + scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); + scm_dynwind_throw_handler (); + scm_dynwind_fluid (catch_data->pre_unwind_running, SCM_BOOL_T); + catch_data->pre_unwind_handler (catch_data->pre_unwind_handler_data, + kind, args); + scm_dynwind_end (); + } + return scm_raise_exception (exn); +} + +static SCM +catch_body (void *data) +{ + struct scm_catch_data *catch_data = data; + + if (catch_data->pre_unwind_handler) { + SCM thunk = scm_c_make_thunk (catch_data->body, catch_data->body_data); + SCM handler = scm_c_make_exception_handler (catch_pre_unwind_handler, data); + SCM fluid = scm_make_thread_local_fluid (SCM_BOOL_F); + catch_data->pre_unwind_running = fluid; + return scm_with_pre_unwind_exception_handler (handler, thunk); + } + + return catch_data->body (catch_data->body_data); +} + SCM scm_c_catch (SCM tag, - scm_t_catch_body body, void *body_data, + scm_t_thunk body, void *body_data, scm_t_catch_handler handler, void *handler_data, scm_t_catch_handler pre_unwind_handler, void *pre_unwind_handler_data) { - SCM sbody, shandler, spre_unwind_handler; - - sbody = scm_i_make_catch_body_closure (body, body_data); - shandler = scm_i_make_catch_handler_closure (handler, handler_data); - if (pre_unwind_handler) - spre_unwind_handler = - scm_i_make_catch_handler_closure (pre_unwind_handler, - pre_unwind_handler_data); - else - spre_unwind_handler = SCM_UNDEFINED; - - return scm_catch_with_pre_unwind_handler (tag, sbody, shandler, - spre_unwind_handler); + struct scm_catch_data data = + { tag, body, body_data, handler, handler_data, pre_unwind_handler, + pre_unwind_handler_data, SCM_BOOL_F }; + + return scm_c_with_exception_handler (tag, catch_post_unwind_handler, &data, + catch_body, &data); } SCM scm_internal_catch (SCM tag, - scm_t_catch_body body, void *body_data, + scm_t_thunk body, void *body_data, scm_t_catch_handler handler, void *handler_data) { return scm_c_catch (tag, @@ -400,28 +183,96 @@ scm_internal_catch (SCM tag, SCM scm_c_with_throw_handler (SCM tag, - scm_t_catch_body body, + scm_t_thunk body, void *body_data, scm_t_catch_handler handler, void *handler_data, int lazy_catch_p) { - SCM sbody, shandler; + struct scm_catch_data data = + { tag, body, body_data, NULL, NULL, handler, handler_data, SCM_BOOL_F }; if (lazy_catch_p) - scm_c_issue_deprecation_warning - ("The LAZY_CATCH_P argument to `scm_c_with_throw_handler' is no longer.\n" - "supported. Instead the handler will be invoked from within the dynamic\n" - "context of the corresponding `throw'.\n" - "\nTHIS COULD CHANGE YOUR PROGRAM'S BEHAVIOR.\n\n" - "Please modify your program to pass 0 as the LAZY_CATCH_P argument,\n" - "and adapt it (if necessary) to expect to be within the dynamic context\n" - "of the throw."); - - sbody = scm_i_make_catch_body_closure (body, body_data); - shandler = scm_i_make_catch_handler_closure (handler, handler_data); - - return scm_with_throw_handler (tag, sbody, shandler); + /* Non-zero lazy_catch_p arguments have been deprecated since + 2010. */ + abort (); + + return catch_body (&data); +} + +static SCM +call_thunk (void* data) +{ + return scm_call_0 (PTR2SCM (data)); +} + +static SCM +call_handler (void* data, SCM a, SCM b) +{ + return scm_call_2 (PTR2SCM (data), a, b); +} + +SCM +scm_catch (SCM key, SCM thunk, SCM handler) +{ + return scm_c_catch (key, call_thunk, SCM2PTR (thunk), + call_handler, SCM2PTR (handler), NULL, NULL); +} + +SCM +scm_catch_with_pre_unwind_handler (SCM key, SCM thunk, SCM handler, + SCM pre_unwind_handler) +{ + if (SCM_UNBNDP (pre_unwind_handler)) + return scm_catch (key, thunk, handler); + + return scm_c_catch (key, call_thunk, SCM2PTR (thunk), + call_handler, SCM2PTR (handler), + call_handler, SCM2PTR (pre_unwind_handler)); +} + +SCM +scm_with_throw_handler (SCM key, SCM thunk, SCM handler) +{ + return scm_c_with_throw_handler (key, call_thunk, SCM2PTR (thunk), + call_handler, SCM2PTR (handler), 0); +} + +SCM +scm_throw (SCM key, SCM args) +{ + SCM throw = scm_variable_ref (throw_var); + if (scm_is_false (throw)) { + SCM port = scm_current_error_port (); + scm_puts ("Pre-boot error; key: ", port); + scm_write (key, port); + scm_puts (", args: ", port); + scm_write (args, port); + abort (); + } + scm_apply_1 (throw, key, args); + /* Should not be reached. */ + abort (); +} + + + +/* Now some support for C bodies and catch handlers */ + +static scm_t_bits tc16_catch_handler; + +SCM +scm_i_make_catch_handler (scm_t_catch_handler handler, void *data) +{ + SCM_RETURN_NEWSMOB2 (tc16_catch_handler, handler, data); +} + +static SCM +apply_catch_handler (SCM clo, SCM args) +{ + scm_t_catch_handler handler = (void*)SCM_SMOB_DATA (clo); + void *data = (void*)SCM_SMOB_DATA_2 (clo); + return handler (data, scm_car (args), scm_cdr (args)); } @@ -490,28 +341,6 @@ scm_handle_by_proc_catching_all (void *handler_data, SCM tag, SCM throw_args) scm_handle_by_message_noexit, NULL); } -/* Derive the an exit status from the arguments to (quit ...). */ -int -scm_exit_status (SCM args) -{ - if (scm_is_pair (args)) - { - SCM cqa = SCM_CAR (args); - - if (scm_is_integer (cqa)) - return (scm_to_int (cqa)); - else if (scm_is_false (cqa)) - return EXIT_FAILURE; - else - return EXIT_SUCCESS; - } - else if (scm_is_null (args)) - return EXIT_SUCCESS; - else - /* A type error. Strictly speaking we shouldn't get here. */ - return EXIT_FAILURE; -} - static int should_print_backtrace (SCM tag, SCM stack) @@ -619,66 +448,13 @@ scm_ithrow (SCM key, SCM args, int no_return SCM_UNUSED) scm_throw (key, args); } -SCM_SYMBOL (scm_stack_overflow_key, "stack-overflow"); -SCM_SYMBOL (scm_out_of_memory_key, "out-of-memory"); - -static SCM stack_overflow_args = SCM_BOOL_F; -static SCM out_of_memory_args = SCM_BOOL_F; - -/* Since these two functions may be called in response to resource - exhaustion, we have to avoid allocating memory. */ - -void -scm_report_stack_overflow (void) -{ - if (scm_is_false (stack_overflow_args)) - abort (); - throw_without_pre_unwind (scm_stack_overflow_key, stack_overflow_args); - - /* Not reached. */ - abort (); -} - -void -scm_report_out_of_memory (void) -{ - if (scm_is_false (out_of_memory_args)) - abort (); - throw_without_pre_unwind (scm_out_of_memory_key, out_of_memory_args); - - /* Not reached. */ - abort (); -} - void scm_init_throw () { - tc16_catch_closure = scm_make_smob_type ("catch-closure", 0); - scm_set_smob_apply (tc16_catch_closure, apply_catch_closure, 0, 0, 1); - - exception_handler_fluid = scm_make_thread_local_fluid (SCM_BOOL_F); - /* This binding is later removed when the Scheme definitions of catch, - throw, and with-throw-handler are created in boot-9.scm. */ - scm_c_define ("%exception-handler", exception_handler_fluid); - - throw_var = scm_c_define ("throw", scm_c_make_gsubr ("throw", 1, 0, 1, - throw_without_pre_unwind)); - - /* Arguments as if from: - - scm_error (stack-overflow, NULL, "Stack overflow", #f, #f); - - We build the arguments manually because we throw without running - pre-unwind handlers. (Pre-unwind handlers could rewind the - stack.) */ - stack_overflow_args = scm_list_4 (SCM_BOOL_F, - scm_from_latin1_string ("Stack overflow"), - SCM_BOOL_F, - SCM_BOOL_F); - out_of_memory_args = scm_list_4 (SCM_BOOL_F, - scm_from_latin1_string ("Out of memory"), - SCM_BOOL_F, - SCM_BOOL_F); + tc16_catch_handler = scm_make_smob_type ("catch-handler", 0); + scm_set_smob_apply (tc16_catch_handler, apply_catch_handler, 0, 0, 1); + + throw_var = scm_c_define ("throw", SCM_BOOL_F); #include "throw.x" } |