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with-display-message: Workaround for bug#63253

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Running arbitrary ELisp code from an atimer is still dangerous,
at least because the regexp engine is not-reentrant, so let's patch up
the case we bumped into.  There are probably many other such holes :-(

* src/alloc.c (garbage_collection_inhibited): Make it non-static.

* src/xdisp.c (garbage_collection_inhibited): Declare it.
(set_message, clear_message): Use it as a proxy for "we're in
a dangerous context like within `probably_quit`".
This commit is contained in:
Stefan Monnier 2023-05-09 22:30:52 -04:00
parent 6924c81a6d
commit 93005cd9dc
2 changed files with 11 additions and 3 deletions
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2
src/alloc.c
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@ -367,7 +367,7 @@ static ptrdiff_t pure_bytes_used_non_lisp;
/* If positive, garbage collection is inhibited. Otherwise, zero. */ /* If positive, garbage collection is inhibited. Otherwise, zero. */
static intptr_t garbage_collection_inhibited; intptr_t garbage_collection_inhibited;
/* The GC threshold in bytes, the last time it was calculated /* The GC threshold in bytes, the last time it was calculated
from gc-cons-threshold and gc-cons-percentage. */ from gc-cons-threshold and gc-cons-percentage. */

12
src/xdisp.c
View file

@ -12810,6 +12810,8 @@ truncate_message_1 (void *a1, Lisp_Object a2)
return false; return false;
} }
extern intptr_t garbage_collection_inhibited;
/* Set the current message to STRING. */ /* Set the current message to STRING. */
static void static void
@ -12819,7 +12821,11 @@ set_message (Lisp_Object string)
eassert (STRINGP (string)); eassert (STRINGP (string));
if (FUNCTIONP (Vset_message_function)) if (FUNCTIONP (Vset_message_function)
/* FIXME: (bug#63253) We should really make the regexp engine re-entrant,
but in the mean time, let's ignore `set-message-function` when
called from `probably_quit`. */
&& !garbage_collection_inhibited)
{ {
specpdl_ref count = SPECPDL_INDEX (); specpdl_ref count = SPECPDL_INDEX ();
specbind (Qinhibit_quit, Qt); specbind (Qinhibit_quit, Qt);
@ -12896,7 +12902,9 @@ clear_message (bool current_p, bool last_displayed_p)
if (current_p) if (current_p)
{ {
if (FUNCTIONP (Vclear_message_function)) if (FUNCTIONP (Vclear_message_function)
/* FIXME: (bug#63253) Same as for `set-message-function` above. */
&& !garbage_collection_inhibited)
{ {
specpdl_ref count = SPECPDL_INDEX (); specpdl_ref count = SPECPDL_INDEX ();
specbind (Qinhibit_quit, Qt); specbind (Qinhibit_quit, Qt);