Re: [PoC] Federated Authn/z with OAUTHBEARER

On Fri, Aug 30, 2024 at 2:49 AM Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
> This looks pretty good to me. Maybe on the naming side, this seems like
> a gratuitous divergence:
>
> +#define jsonapi_createStringInfo makeStringInfo

Whoops, fixed.

> Seems ok to me as is. I think the purpose of JSONAPI_USE_PQEXPBUFFER is
> adequately explained by this comment
>
> +/*
> + * By default, we will use palloc/pfree along with StringInfo. In libpq,
> + * use malloc and PQExpBuffer, and return JSON_OUT_OF_MEMORY on
> out-of-memory.
> + */
> +#ifdef JSONAPI_USE_PQEXPBUFFER
>
> For some of the other proposed names, I'd be afraid that someone might
> think you are free to mix and match APIs, OOM behavior, and compilation
> options.

Yeah, that's fair.

> Some comments on src/include/common/jsonapi.h:
>
> -#include "lib/stringinfo.h"
>
> I suspect this will fail headerscheck? Probably needs an exception
> added there.

Currently it passes on my machine and the cfbot. The
forward-declaration of the struct should be enough to make clients
happy. Or was there a different way to break it?

> +#ifdef JSONAPI_USE_PQEXPBUFFER
> +#define StrValType PQExpBufferData
> +#else
> +#define StrValType StringInfoData
> +#endif
>
> Maybe use jsonapi_StrValType here.

Done.

> +typedef struct StrValType StrValType;
>
> I don't think that is needed. It would just duplicate typedefs that
> already exist elsewhere, depending on what StrValType is set to.

Okay, removed.

> The parse_strval field could use a better explanation.
>
> I actually don't understand the need for this field. AFAICT, this is
> just used to record whether strval is valid.

No, it's meant to track the value of the need_escapes argument to the
constructor. I've renamed it and moved the assignment to hopefully
make that a little more obvious. WDYT?

> But in the cases where
> it's not valid, why do we need to record that? Couldn't you just return
> failed_oom in those cases?

We can do that if you'd like. I was just worried about using a valid
(broken) value of PQExpBuffer as a sentinel instead of a separate
flag. It would work as long as reviewers stay vigilant, but if we go
that direction and someone adds an unchecked

lex->strval = jsonapi_makeStringInfo();
// should check for NULL now, but we forgot

into a future patch, an allocation failure in _shlib builds would
silently disable string escaping instead of resulting in a
JSON_OUT_OF_MEMORY later.

Thanks,
--Jacob