Re: Foreign memory context read - Mailing list pgsql-hackers

From Vaibhav Kaushal
Subject Re: Foreign memory context read
Date
Msg-id BANLkTina2ZXKh1EDHSTGQFJbqw8a-Cqbng@mail.gmail.com
Whole thread Raw
In response to Re: Foreign memory context read  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
<p>Oh...well... I messed it up! Thanks a lot for that. The problem I think is the bool pointer. Will check it
soon.<p>--<br/> Sent from my Android<div class="gmail_quote">On 23 May 2011 19:28, "Tom Lane" <<a
href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>>wrote:<br type="attribution" />> Vaibhav Kaushal <<a
href="mailto:vaibhavkaushal123@gmail.com">vaibhavkaushal123@gmail.com</a>>writes:<br /> >> My mind started
wanderingafter that error. Now, actually, i was trying to<br />>> do something like this:<br />> <br
/>>>*last_result = palloc0(sizeof(Datum));<br />>> bool *isnnuull = true;<br />>> *last_result =
slot_getattr(slot,num_atts, *isnnuull);<br /> > <br />> This seems utterly confused about data types. The first
linethinks<br />> that last_result is of type Datum ** (ie, pointer to pointer to Datum),<br />> since it's
storinga pointer-to-Datum through it. The third line<br /> > however is treating last_result as of type Datum *,
sinceit's storing<br />> a Datum (not pointer to Datum) through it. And the second line is<br />> assigning
"true"(a bool value) to a variable declared as pointer to<br /> > bool, which you then proceed to incorrectly
dereferencewhile passing it<br />> as the last argument to slot_getattr. The code will certainly crash on<br />>
thatderef, independently of the multiple other bugs here.<br /> > <br />> Recommendation: gcc is your friend. Pay
attentionto the warnings it<br />> gives you.<br />> <br />> regards, tom lane<br /></div> 

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