Re: Fix a bug in extension_file_exists()

> On Feb 9, 2026, at 18:02, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>
> On 09/02/2026 11:21, Chao Li wrote:
>> I just noticed a bug in extension_file_exists():
>> ```
>> bool
>> extension_file_exists(const char *extensionName)
>> {
>> bool result = false;
>> List *locations;
>> DIR *dir;
>> struct dirent *de;
>> locations = get_extension_control_directories();
>> foreach_ptr(char, location, locations) // <== Here type char is wrong
>> {
>> dir = AllocateDir(location);
>> ```
>> get_extension_control_directories() returns a list of ExtensionLocation, but the loop iterates it as if it contained char *, which is incorrect. As a result, AllocateDir() and ReadDir() are called with the wrong type.
>> This bug is only triggered on an error path, when PostgreSQL is deciding whether to emit a hint. For example:
>> ```
>> evantest=# create function f() returns int LANGUAGE plpython3u as $$return 1$$;
>> ERROR: language "plpython3u" does not exist
>> ```
>> No hint is printed.
>> With this patch applied:
>> ```
>> evantest=# create function f() returns int LANGUAGE plpython3u as $$return 1$$;
>> ERROR: language "plpython3u" does not exist
>> HINT: Use CREATE EXTENSION to load the language into the database.
>> ```
>> So the hint is shown as intended.
>> Attached is a patch fixing the iteration to use ExtensionLocation and location->loc consistently.
>
> Yep, good catch. This went wrong in commit f3c9e341cd, which changed the type of objects in the list from "char *" to "ExtensionLocation *". So this is master only, stable branches are not affected.
>
> I will push the fix shortly, thanks!
>
> - Heikki
>

Thanks for pushing.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/