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random: Rely on free(NULL) being safe for random status freeing #10246

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Merged
merged 2 commits into from
Jan 10, 2023
Merged

random: Rely on free(NULL) being safe for random status freeing #10246

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79df3d0
random: Rely on `free(NULL)` being safe for random status freeing
TimWolla Jan 6, 2023
54ff5a4
random: Restructure `php_random_status_free()` to not early-return
TimWolla Jan 7, 2023
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13 changes: 6 additions & 7 deletions ext/random/random.c
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Original file line number Diff line number Diff line change
Expand Up @@ -234,7 +234,7 @@ static zend_object *php_random_randomizer_new(zend_class_entry *ce)
static void randomizer_free_obj(zend_object *object) {
php_random_randomizer *randomizer = php_random_randomizer_from_obj(object);

if (randomizer->is_userland_algo && randomizer->status) {
if (randomizer->is_userland_algo) {
php_random_status_free(randomizer->status, false);
}

Expand All @@ -261,9 +261,11 @@ PHPAPI php_random_status *php_random_status_copy(const php_random_algo *algo, ph

PHPAPI void php_random_status_free(php_random_status *status, const bool persistent)
{
if (status->state) {
pefree(status->state, persistent);
if (status == NULL) {
return;
}
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Can status ever be NULL or should an assertion be added?

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See https://chat.stackoverflow.com/transcript/message/55792527#55792527 for context. I'm used to free()-style functions being a noop if passed NULL and consider it a good thing, because is avoids checking for NULL in every place that frees something that might be absent. In this case there might be no such place, but still this should just work in case there is.

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I've just restructured the method a little, though. Instead of returning early, it checks for NULL before dereferencing status and just passes a possible-NULL status to pefree(). This pattern is a little more common for more complex structs.


pefree(status->state, persistent);
pefree(status, persistent);
}

Expand All @@ -285,10 +287,7 @@ PHPAPI void php_random_engine_common_free_object(zend_object *object)
{
php_random_engine *engine = php_random_engine_from_obj(object);

if (engine->status) {
php_random_status_free(engine->status, false);
}

php_random_status_free(engine->status, false);
zend_object_std_dtor(object);
}

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