Обсуждение: Segfault using heap_form_tuple

Greetings,
I'm having a problem using heap_form_tuple. I'm trying to form a HeapTuple to use it later with simple_heap_insert. My
codelooks like this: 

------------------

Datum *values;
bool *nulls;
int natts;
TupleDesc tupDesc;
HeapTuple tuple;
...
tupDesc = RelationGetDescr(...my previously opened relation...);
natts = tupDesc->natts;

values = (Datum *)palloc(natts*sizeof(Datum *));
nulls = (bool *)palloc(natts*sizeof(bool *));

memset(nulls, false, natts * sizeof(nulls));

values[0] = ...GetDatum(...my datum...);
...
values[natts-1] = ...GetDatum(...my datum...);
...
tuple = heap_form_tuple(tupDesc, values, nulls);

------------------

When I come to last line, I get these errors (I'm using valgrind):

==25850== Source and destination overlap in memcpy(0x8BCB070, 0x4CF2480, 496753820)
==25850==    at 0x4024586: memcpy (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==25850==    by 0x808C811: heap_fill_tuple (in /usr/local/pgsql/bin/postgres)
==25850==    by 0x808D72F: heap_form_tuple (in /usr/local/pgsql/bin/postgres)
...
==25850== Invalid read of size 1
==25850==    at 0x40245A1: memcpy (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==25850==    by 0x808C811: heap_fill_tuple (in /usr/local/pgsql/bin/postgres)
==25850==    by 0x808D72F: heap_form_tuple (in /usr/local/pgsql/bin/postgres)
...
==25850==  Address 0x8BCB027 is 1 bytes before a block of size 496,753,892 alloc'd
==25850==    at 0x4022825: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==25850==    by 0x82BE278: AllocSetAlloc (in /usr/local/pgsql/bin/postgres)
==25850==    by 0x82BEE91: MemoryContextAllocZero (in /usr/local/pgsql/bin/postgres)
==25850==    by 0x808D694: heap_form_tuple (in /usr/local/pgsql/bin/postgres)
...
==25850==  Address 0x8BCB027 is 2 bytes before a block of size 496,753,892 alloc'd
...
==25850==  Address 0x8BCB027 is 3 bytes before a block of size 496,753,892 alloc'd
...
==25850==  Address 0x8BCB027 is 4 bytes before a block of size 496,753,892 alloc'd
...
==25850== Process terminating with default action of signal 11 (SIGSEGV)
==25850==  Access not within mapped region at address 0x8BCAFFF
==25850==    at 0x40245A1: memcpy (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==25850==    by 0x808C811: heap_fill_tuple (in /usr/local/pgsql/bin/postgres)
==25850==    by 0x808D72F: heap_form_tuple (in /usr/local/pgsql/bin/postgres)

If I work on tables with only 1 attribute, I use normal variables (Datum values, bool nulls) instead of arrays, and
usingheap_form_tuple(TupleDesc td, &values, &nulls) works flawlessly. What am i missing? 

Thanks in advance for help,
Claudio Rossi

On Wed, Apr 9, 2008 at 10:48 PM, Claudio Rossi <wind.claudio@inwind.it> wrote:

>  nulls = (bool *)palloc(natts*sizeof(bool *));
>

May not be related to segfault you are seeing, but this looks completely wrong.
You want array of bool and not (bool *).


Thanks,
Pavan


-- 
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com

"Claudio Rossi" <wind.claudio@inwind.it> writes:
> values[0] = ...GetDatum(...my datum...);
> ...
> values[natts-1] = ...GetDatum(...my datum...);

You've omitted the details that probably matter.  My guess is that
you're inappropriately converting one of these values to a Datum,
or converting it to a Datum that's not really of the type the
tuple descriptor specifies.
        regards, tom lane

> >  nulls = (bool *)palloc(natts*sizeof(bool *));
> >
>
> May not be related to segfault you are seeing, but this looks completely wrong.
> You want array of bool and not (bool *).

Yeah, you are right but in the original code it's:

values = (Datum *) palloc(natts * sizeof(Datum));
nulls = (bool *) palloc(natts * sizeof(bool));

I just typed it wrong, I didn't copy and paste. I also forgot to add this line (from valgrind log) at the beginning of
errorsequence: 

==30549== Warning: set address range perms: large range 496753892 (undefined)

I'm clueless, any hints?

> You've omitted the details that probably matter.  My guess is that
> you're inappropriately converting one of these values to a Datum,
> or converting it to a Datum that's not really of the type the
> tuple descriptor specifies.
>
>             regards, tom lane

Mate, you just won a beer :)

You guessed it right, I was trying to "CStringGetDatum" into a text field, now i solved it with

values[n] = DirectFunctionCall1(textin, CStringGetDatum(...string...));

Thank you very much!

Claudio Rossi

"Claudio Rossi" <wind.claudio@inwind.it> writes:
> You guessed it right, I was trying to "CStringGetDatum" into a text field, now i solved it with

> values[n] = DirectFunctionCall1(textin, CStringGetDatum(...string...));

If you're working in CVS HEAD there's an easier way --- see
CStringGetTextDatum.
        regards, tom lane