Re: [PATCH] fix segv with corrupt tag object

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 26, 2019, 17:20 UTC
Message-ID: <xmqqo90bhmi3.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20190826115715.GB71935@jessup.stsp.name>

Stefan Sperling <stsp@stsp.name> writes:

> The root cause of this bug seems to be that the valid assumption
> that obj->parsed implies a successfully parsed object is broken by
> parse_tag_buffer() because this function sets the 'parsed' flag even
> if errors occur during parsing.

I am mildly negative about that approach. obj->parsed is about "we've done all we need to do to attempt parsing this object" (so that next person who gets hold of the object knows that fact---one of the reasons why may be that the caller who wants to ensure that the fields are ready to be accessed does not have to spend extra cycles, but that is not the only one). Those that want to look at various fields in the object (e.g. the tagged object of a tag, the tagger identity of a tag, etc.) should be prepared to see and react to NULL in there so that they can gracefully handle "slightly" corrupt objects.