Re: Print warning when I execute my own extension function

now I found a bug in this code.
I found the code of this part below is wrong

```
char *buffer = palloc(7 * sizeof(char));
>> unsigned int offset = sizeof(buffer); // wrong
buffer[--offset] = '\0'; /* here */
```

Thank you for replying

2022년 2월 20일 (일) 오후 11:51, Dong Wook Lee <sh95119(at)gmail(dot)com>님이 작성:
>
> I found a source code line that prints warning in the source code
> (src/backend/utils/mmgr/aset.c, line 1496)
> /*
> │ 1492 * Check for overwrite of
> padding space in an allocated chunk.
> │ 1493 */
> │ 1494 if (chunk->aset == (void *)
> set && dsize < chsize &&
> │ 1495 !sentinel_ok(chunk,
> ALLOC_CHUNKHDRSZ + dsize))
> │B+>1496 elog(WARNING, "problem
> in alloc set %s: detected write past chunk end in block %p, chunk %p",
> │ 1497 name, block, chunk);
>
> In my extension c code.
> I assigned value at the allocated memory address
> and I found this assigned statement occurs warning
> should I don't use it like this?
> ```
> char *buffer = palloc(7 * sizeof(char));
> unsigned int offset = sizeof(buffer);
> > buffer[--offset] = '\0'; /* here */
> ```
>
>
>
> 2022년 2월 20일 (일) 오후 7:29, Julien Rouhaud <rjuju123(at)gmail(dot)com>님이 작성:
> >
> > Hi,
> >
> > On Sun, Feb 20, 2022 at 07:23:56PM +0900, Dong Wook Lee wrote:
> > > Hi hackers,
> > > I've read in this blog (
> > > http://big-elephants.com/2015-10/writing-postgres-extensions-part-i/)
> > > and I wrote an extension about base36_encode with c code
> > > but when I executed a query like this below I got a warning below.
> > >
> > > ```
> > > postgres=# SELECT base36_encode(123);
> > > WARNING: problem in alloc set ExprContext: detected write past chunk end
> > > in block 0x55fb75334d40, chunk 0x55fb75334d68
> > > WARNING: problem in alloc set ExprContext: detected write past chunk end
> > > in block 0x55fb75334d40, chunk 0x55fb75334d68
> > > base36_encode
> > > ---------------
> > > 3f
> > > (1 row)
> > > ```
> > >
> > > I don't know what this warning means and how I can fix it.
> >
> > It means that you have some problem in your memory allocation. You can refer
> > to src/backend/utils/mmgr/aset.c for more details on those safety checks.