Re: pg_dump's checkSeek() seems inadequate

Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>> Tom Lane wrote:
>>     
>>> A somewhat more plausible scenario is that somebody might hope that
>>> they could do something like this:
>>>
>>> echo 'some custom header' >pg.dump
>>> pg_dump -Fc >>pg.dump
>>>       
>
>   
>> What would anyone hope to achieve by such a manoeuvre, even if it 
>> worked, which I am close the dead sure it would not?
>>     
>
> It looks to me like it probably would actually work, so far as pg_dump
> is concerned, but _discoverArchiveFormat() would break it because that
> tries to do an unconditional fseeko(fp, 0, SEEK_SET) (and the position
> counting is screwed up even if the fseeko fails).  That could probably
> be fixed if anyone thought this scenario was interesting enough to
> justify work directed specifically at it.  
>   

IIRC pg_restore expects the archive to begin with the header and TOC 
produced by pg_dump. Maybe I'm being dense, but I'm not able to see how 
prefixing that with something else could possibly do something useful or 
workable.

cheers

andrew