Re: [patch]overallocate memory for curly braces in array_out - Mailing list pgsql-hackers

From Keiichi Hirobe
Subject Re: [patch]overallocate memory for curly braces in array_out
Date
Msg-id CAH=EFxEc+V=F-dO6HAPnbaZSZzqjkEJywkcxCfp=Ki=VfDEB8g@mail.gmail.com
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In response to Re: [patch]overallocate memory for curly braces in array_out  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [patch]overallocate memory for curly braces in array_out  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Hi,

Thanks for the reply.

I am not sure whether to fix another bug, but I fixed and I attached a new patch,
please check it.

Please note that I inserted a line for updating "overall_length" at line 1185.

I checked below case.

select ARRAY[ARRAY[1,2,3],ARRAY[4,5,6]]; (regular case)
select '[3:4][2:4]={{1,2,3},{4,5,6}}'::_int4; (needdims case)
select  ARRAY['a"bc','def']; (needquote case)


Cheers,
Keiichi Hirobe

2018年9月24日(月) 23:46 Tom Lane <tgl@sss.pgh.pa.us>:
Keiichi Hirobe <chalenge.akane@gmail.com> writes:
> Attached is a patch that fixes a bug
> for miscounting total number of curly braces in output string in array_out.

Wow, good catch!

Testing this, I found there's a second way in which the space calculation
is off: it always allocated one more byte than required, as a result of
counting one more comma than is really required.  That's not nearly as
significant as the curly-brace miscount, but it still got in the way of
doing this:

*** 1234,1239 ****
--- 1243,1251 ----
  #undef APPENDSTR
  #undef APPENDCHAR

+       /* Assert that we calculated the string length accurately */
+       Assert(overall_length == (p - retval + 1));
+
        pfree(values);
        pfree(needquotes);


which seemed to me like a good idea now that we know this code isn't
so perfect as all that.

Will push shortly.

                        regards, tom lane
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