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Make checking for liveness of global values more precise.

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We can't just use a hash lookup because a global and a local reference
might refer to the same Lisp object.

* src/emacs-module.c (module_free_global_ref): More precise check for
global liveness.

* test/data/emacs-module/mod-test.c (Fmod_test_globref_invalid_free):
New test module function.
(emacs_module_init): Export it.

* test/src/emacs-module-tests.el
(module--test-assertions--globref-invalid-free): New unit test.
This commit is contained in:
Philipp Stephani 2020-07-25 23:23:19 +02:00
parent 6355a3ec62
commit 9f01ce6327
3 changed files with 33 additions and 5 deletions
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13
src/emacs-module.c
View file

@ -468,6 +468,14 @@ module_free_global_ref (emacs_env *env, emacs_value global_value)
Lisp_Object obj = value_to_lisp (global_value);
ptrdiff_t i = hash_lookup (h, obj, NULL);
if (module_assertions)
{
ptrdiff_t n = 0;
if (! module_global_reference_p (global_value, &n))
module_abort ("Global value was not found in list of %"pD"d globals",
n);
}
if (i >= 0)
{
Lisp_Object value = HASH_VALUE (h, i);
@ -476,11 +484,6 @@ module_free_global_ref (emacs_env *env, emacs_value global_value)
if (--ref->refcount == 0)
hash_remove_from_table (h, obj);
}
else if (module_assertions)
{
module_abort ("Global value was not found in list of %"pD"d globals",
h->count);
}
}
static enum emacs_funcall_exit

14
test/data/emacs-module/mod-test.c
View file

@ -201,7 +201,19 @@ Fmod_test_globref_free (emacs_env *env, ptrdiff_t nargs, emacs_value args[],
return env->intern (env, "ok");
}
/* Treat a local reference as global and free it. Module assertions
should detect this case even if a global reference representing the
same object also exists. */
static emacs_value
Fmod_test_globref_invalid_free (emacs_env *env, ptrdiff_t nargs,
emacs_value *args, void *data)
{
emacs_value local = env->make_integer (env, 9876);
env->make_global_ref (env, local);
env->free_global_ref (env, local); /* Not allowed. */
return env->intern (env, "nil");
}
/* Return a copy of the argument string where every 'a' is replaced
with 'b'. */
@ -694,6 +706,8 @@ emacs_module_init (struct emacs_runtime *ert)
1, 1, NULL, NULL);
DEFUN ("mod-test-globref-make", Fmod_test_globref_make, 0, 0, NULL, NULL);
DEFUN ("mod-test-globref-free", Fmod_test_globref_free, 4, 4, NULL, NULL);
DEFUN ("mod-test-globref-invalid-free", Fmod_test_globref_invalid_free, 0, 0,
NULL, NULL);
DEFUN ("mod-test-string-a-to-b", Fmod_test_string_a_to_b, 1, 1, NULL, NULL);
DEFUN ("mod-test-userptr-make", Fmod_test_userptr_make, 1, 1, NULL, NULL);
DEFUN ("mod-test-userptr-get", Fmod_test_userptr_get, 1, 1, NULL, NULL);

11
test/src/emacs-module-tests.el
View file

@ -301,6 +301,17 @@ during garbage collection."
(mod-test-invalid-finalizer)
(garbage-collect)))
(ert-deftest module--test-assertions--globref-invalid-free ()
"Check that -module-assertions detects invalid freeing of a
local reference."
(skip-unless (or (file-executable-p mod-test-emacs)
(and (eq system-type 'windows-nt)
(file-executable-p (concat mod-test-emacs ".exe")))))
(module--test-assertion
(rx "Global value was not found in list of " (+ digit) " globals")
(mod-test-globref-invalid-free)
(garbage-collect)))
(ert-deftest module/describe-function-1 ()
"Check that Bug#30163 is fixed."
(with-temp-buffer