eval.c: Add new var lisp-eval-depth-reserve
Rather than blindly increase `max-lisp-eval-depth` when entering the debugger or running `signal-hook-function`, use this new "reserve" to keep track of how much we have grown the stack for "debugger" purposes so that for example recursive calls to `signal-hook-function` can't eat up the whole C stack. * src/eval.c (max_ensure_room): Rewrite. (restore_stack_limits): Move before `max_ensure_room`. Rewrite. (call_debugger, signal_or_quit): Adjust calls accordingly. Also grow `max-lisp-eval-depth` for `hander-bind` handlers. (init_eval_once): Don't initialize `max_lisp_eval_depth` here. (syms_of_eval): Initialize it here instead. Add new var `lisp-eval-depth-reserve`. * doc/lispref/eval.texi (Eval): Add `lisp-eval-depth-reserve`.
This commit is contained in:
Stefan Monnier
parent
a5dcc1abea
commit
02edbc88a1
3 changed files with 57 additions and 30 deletions
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@ -844,11 +844,24 @@ function body forms, as well as explicit calls in Lisp code.
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The default value of this variable is 1600. If you set it to a value
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less than 100, Lisp will reset it to 100 if the given value is
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reached. Entry to the Lisp debugger increases the value, if there is
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little room left, to make sure the debugger itself has room to
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execute.
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reached.
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@end defopt
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@defopt lisp-eval-depth-reserve
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In order to be able to debug infinite recursion errors, when invoking the
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Lisp debugger, Emacs increases temporarily the value of
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@code{max-lisp-eval-depth}, if there is little room left, to make sure
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the debugger itself has room to execute. The same happens when
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running the handler of a @code{handler-bind}. @xref{Handling Errors}.
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The variable @code{lisp-eval-depth-reserve} bounds the extra depth
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that Emacs can add to @code{max-lisp-eval-depth} for those
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exceptional circumstances.
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The default value of this variable is 200.
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@end defopt
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@defvar values
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The value of this variable is a list of the values returned by all the
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expressions that were read, evaluated, and printed from buffers
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5
etc/NEWS
5
etc/NEWS
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@ -1395,6 +1395,11 @@ This is like 'require', but it checks whether the argument 'feature'
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is already loaded, in which case it either signals an error or
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forcibly reloads the file that defines the feature.
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+++
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** New variable 'lisp-eval-depth-reserve'.
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It puts a limit to the amount by which Emacs can temporarily increase
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'max-lisp-eval-depth' when handling signals.
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+++
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** New special form 'handler-bind'.
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Provides a functionality similar to `condition-case` except it runs the
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63
src/eval.c
63
src/eval.c
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@ -212,7 +212,6 @@ void
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init_eval_once (void)
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{
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/* Don't forget to update docs (lispref node "Eval"). */
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max_lisp_eval_depth = 1600;
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Vrun_hooks = Qnil;
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pdumper_do_now_and_after_load (init_eval_once_for_pdumper);
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}
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@ -248,22 +247,29 @@ init_eval (void)
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redisplay_deep_handler = NULL;
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}
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/* Ensure that *M is at least A + B if possible, or is its maximum
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value otherwise. */
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static void
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max_ensure_room (intmax_t *m, intmax_t a, intmax_t b)
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{
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intmax_t sum = ckd_add (&sum, a, b) ? INTMAX_MAX : sum;
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*m = max (*m, sum);
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}
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/* Unwind-protect function used by call_debugger. */
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static void
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restore_stack_limits (Lisp_Object data)
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{
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integer_to_intmax (data, &max_lisp_eval_depth);
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intmax_t old_depth;
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integer_to_intmax (data, &old_depth);
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lisp_eval_depth_reserve += max_lisp_eval_depth - old_depth;
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max_lisp_eval_depth = old_depth;
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}
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/* Try and ensure that we have at least B dpeth available. */
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static void
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max_ensure_room (intmax_t b)
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{
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intmax_t sum = ckd_add (&sum, lisp_eval_depth, b) ? INTMAX_MAX : sum;
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intmax_t diff = min (sum - max_lisp_eval_depth, lisp_eval_depth_reserve);
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if (diff <= 0)
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return;
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intmax_t old_depth = max_lisp_eval_depth;
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max_lisp_eval_depth += diff;
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lisp_eval_depth_reserve -= diff;
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/* Restore limits after leaving the debugger. */
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record_unwind_protect (restore_stack_limits, make_int (old_depth));
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}
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/* Call the Lisp debugger, giving it argument ARG. */
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@ -274,16 +280,12 @@ call_debugger (Lisp_Object arg)
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bool debug_while_redisplaying;
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specpdl_ref count = SPECPDL_INDEX ();
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Lisp_Object val;
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intmax_t old_depth = max_lisp_eval_depth;
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/* The previous value of 40 is too small now that the debugger
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prints using cl-prin1 instead of prin1. Printing lists nested 8
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deep (which is the value of print-level used in the debugger)
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currently requires 77 additional frames. See bug#31919. */
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max_ensure_room (&max_lisp_eval_depth, lisp_eval_depth, 100);
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/* Restore limits after leaving the debugger. */
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record_unwind_protect (restore_stack_limits, make_int (old_depth));
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max_ensure_room (100);
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#ifdef HAVE_WINDOW_SYSTEM
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if (display_hourglass_p)
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@ -1802,16 +1804,13 @@ signal_or_quit (Lisp_Object error_symbol, Lisp_Object data, bool keyboard_quit)
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/* This hook is used by edebug. */
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if (! NILP (Vsignal_hook_function)
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&& ! NILP (error_symbol)
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/* Don't try to call a lisp function if we've already overflowed
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the specpdl stack. */
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&& specpdl_ptr < specpdl_end)
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&& ! NILP (error_symbol))
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{
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/* Edebug takes care of restoring these variables when it exits. */
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max_ensure_room (&max_lisp_eval_depth, lisp_eval_depth, 20);
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specpdl_ref count = SPECPDL_INDEX ();
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max_ensure_room (20);
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/* FIXME: 'handler-bind' makes `signal-hook-function' obsolete? */
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call2 (Vsignal_hook_function, error_symbol, data);
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unbind_to (count, Qnil);
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}
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conditions = Fget (real_error_symbol, Qerror_conditions);
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@ -1849,9 +1848,12 @@ signal_or_quit (Lisp_Object error_symbol, Lisp_Object data, bool keyboard_quit)
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Lisp_Object error_data
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= (NILP (error_symbol)
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? data : Fcons (error_symbol, data));
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specpdl_ref count = SPECPDL_INDEX ();
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max_ensure_room (20);
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push_handler (make_fixnum (skip + h->bytecode_dest),
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SKIP_CONDITIONS);
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call1 (h->val, error_data);
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unbind_to (count, Qnil);
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pop_handler ();
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}
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continue;
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@ -1901,8 +1903,8 @@ signal_or_quit (Lisp_Object error_symbol, Lisp_Object data, bool keyboard_quit)
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&& NILP (Vinhibit_debugger)
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&& !NILP (Ffboundp (Qdebug_early)))
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{
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max_ensure_room (&max_lisp_eval_depth, lisp_eval_depth, 100);
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specpdl_ref count = SPECPDL_INDEX ();
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max_ensure_room (100);
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AUTO_STRING (redisplay_trace, "*Redisplay-trace*");
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Lisp_Object redisplay_trace_buffer;
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AUTO_STRING (gap, "\n\n\n\n"); /* Separates things in *Redisplay-trace* */
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@ -4345,6 +4347,13 @@ actual stack overflow in C, which would be fatal for Emacs.
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You can safely make it considerably larger than its default value,
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if that proves inconveniently small. However, if you increase it too far,
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Emacs could overflow the real C stack, and crash. */);
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max_lisp_eval_depth = 1600;
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DEFVAR_INT ("lisp-eval-depth-reserve", lisp_eval_depth_reserve,
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doc: /* Extra depth that can be allocated to handle errors.
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This is the max depth that the system will add to `max-lisp-eval-depth'
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when calling debuggers or `handler-bind' handlers. */);
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lisp_eval_depth_reserve = 200;
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DEFVAR_LISP ("quit-flag", Vquit_flag,
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doc: /* Non-nil causes `eval' to abort, unless `inhibit-quit' is non-nil.
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