Thread: Segfault from PL/Perl Returning vstring
At least I think it's a segfault. This function returns a vstring: CREATE OR REPLACE FUNCTION wtf( ) RETURNS text LANGUAGE plperl IMMUTABLE STRICT AS $X$ return $^V; $X$; Here's what happens when I call it: try=# select wtf(); server closed the connection unexpectedlyThis probably means the server terminated abnormallybefore or while processing therequest. The connection to the server was lost. Attempting reset: Failed. !> So I think that it doesn't know what to do with vstrings. They should probably never be returned (they're mostly deprecated),but if they are, they should be cast to text, I think. Best, David
David E. Wheeler wrote:
> At least I think it's a segfault. This function returns a vstring:
>
> CREATE OR REPLACE FUNCTION wtf(
> ) RETURNS text LANGUAGE plperl IMMUTABLE STRICT AS $X$
> return $^V;
> $X$;
>
> Here's what happens when I call it:
>
> try=# select wtf();
> server closed the connection unexpectedly
> This probably means the server terminated abnormally
> before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
> !>
>
> So I think that it doesn't know what to do with vstrings. They should probably never be returned (they're mostly
deprecated),but if they are, they should be cast to text, I think.
>
>
>
It's not doing that for me.
The plperl code has no way at all of knowing that the bytes you are
returning come from $^V. If you really want the version back, do what
the perl docs tell you and sprintf the value:
andrew=# CREATE OR REPLACE FUNCTION wtf( ) RETURNS text LANGUAGE plperl IMMUTABLE STRICT AS $X$ return
sprintf("%vd",$^V); $X$; CREATE FUNCTION andrew=# select wtf(); wtf ------- 5.8.8
BTW, this should arguably not be an immutable function. You could
replace the perl library, so it's not solely dependent on the input for
the result.
cheers
andrew
On Dec 21, 2009, at 11:46 AM, Andrew Dunstan wrote: > It's not doing that for me. Odd. > The plperl code has no way at all of knowing that the bytes you are returning come from $^V. If you really want the versionback, do what the perl docs tell you and sprintf the value: It works fine if I return `"$^V"`. > BTW, this should arguably not be an immutable function. You could replace the perl library, so it's not solely dependenton the input for the result. Yeah, that's leftover from trying to troubleshoot another problem. More on that in a bit. Best, David
On mån, 2009-12-21 at 14:46 -0500, Andrew Dunstan wrote: > BTW, this should arguably not be an immutable function. You could > replace the perl library, so it's not solely dependent on the input > for > the result. By this logic, no function could be immutable, because you could replace the C library or parts of the kernel.
Peter Eisentraut wrote: > On mån, 2009-12-21 at 14:46 -0500, Andrew Dunstan wrote: > >> BTW, this should arguably not be an immutable function. You could >> replace the perl library, so it's not solely dependent on the input >> for >> the result. >> > > By this logic, no function could be immutable, because you could replace > the C library or parts of the kernel. > > *shrug* Maybe, OTOH upgrading perl is not such an unusual operation, and doing so *will* affect this value. It's a bit hard to see why one would want the perl version to be immutable. It doesn't look like it would be much use in an index .... I think people are generally safer not marking functions immutable unless they actually need them to be. cheers andrew
On Mon, Dec 21, 2009 at 02:46:17PM -0500, Andrew Dunstan wrote: > > > David E. Wheeler wrote: >> At least I think it's a segfault. This function returns a vstring: >> >> CREATE OR REPLACE FUNCTION wtf( >> ) RETURNS text LANGUAGE plperl IMMUTABLE STRICT AS $X$ >> return $^V; >> $X$; >> >> Here's what happens when I call it: >> >> try=# select wtf(); >> server closed the connection unexpectedly >> This probably means the server terminated abnormally >> before or while processing the request. >> The connection to the server was lost. Attempting reset: Failed. >> !> >> >> So I think that it doesn't know what to do with vstrings. They should probably never be returned (they're mostly deprecated),but if they are, they should be cast to text, I think. > > It's not doing that for me. You're using 5.8.8. In 5.10.0 $^V was changed to be an object. I'm working in that area. I'll look into it. Tim.
On Dec 21, 2009, at 2:13 PM, Tim Bunce wrote:
> You're using 5.8.8. In 5.10.0 $^V was changed to be an object.
>
> I'm working in that area. I'll look into it.
While you're at it, I have a new problem:
CREATE OR REPLACE FUNCTION wtf( expression text ) RETURNS text LANGUAGE plperl AS $$ return
"{$_[0]}"; $$;
try=# select wtf('foo'); wtf ----- { (1 row)
Note how I don't even get the closing "}". This does not happen with PL/PerlU. The denizens of #postgresql think that
there'ssome sort of issue with Safe and Encode or Encode::Alias (the latter `require`s Encode in two if its methods).
Canyou replicate it? It's driving me absolutely batshit. I'm using Perl 5.10.2, Safe 2.20, and Encode 2.39.
Thanks,
David
On Dec 21, 2009, at 2:34 PM, David E. Wheeler wrote:
> On Dec 21, 2009, at 2:13 PM, Tim Bunce wrote:
>
>> You're using 5.8.8. In 5.10.0 $^V was changed to be an object.
>>
>> I'm working in that area. I'll look into it.
>
> While you're at it, I have a new problem:
>
> CREATE OR REPLACE FUNCTION wtf(
> expression text
> ) RETURNS text LANGUAGE plperl AS $$
> return "{$_[0]}";
> $$;
>
> try=# select wtf('foo');
> wtf
> -----
> {
> (1 row)
>
> Note how I don't even get the closing "}". This does not happen with PL/PerlU. The denizens of #postgresql think that
there'ssome sort of issue with Safe and Encode or Encode::Alias (the latter `require`s Encode in two if its methods).
Canyou replicate it? It's driving me absolutely batshit. I'm using Perl 5.10.2, Safe 2.20, and Encode 2.39.
Also, my encoding is en_US.UTF-8. I think it matter that it's UTF-8, to judge by the
if (GetDatabaseEncoding() == PG_UTF8)
Block in plperl.c.
Thanks,
David
David E. Wheeler wrote:
> On Dec 21, 2009, at 2:34 PM, David E. Wheeler wrote:
>
>
>> On Dec 21, 2009, at 2:13 PM, Tim Bunce wrote:
>>
>>
>>> You're using 5.8.8. In 5.10.0 $^V was changed to be an object.
>>>
>>> I'm working in that area. I'll look into it.
>>>
>> While you're at it, I have a new problem:
>>
>> CREATE OR REPLACE FUNCTION wtf(
>> expression text
>> ) RETURNS text LANGUAGE plperl AS $$
>> return "{$_[0]}";
>> $$;
>>
>> try=# select wtf('foo');
>> wtf
>> -----
>> {
>> (1 row)
>>
>> Note how I don't even get the closing "}". This does not happen with PL/PerlU. The denizens of #postgresql think
thatthere's some sort of issue with Safe and Encode or Encode::Alias (the latter `require`s Encode in two if its
methods).Can you replicate it? It's driving me absolutely batshit. I'm using Perl 5.10.2, Safe 2.20, and Encode 2.39.
>>
>
> Also, my encoding is en_US.UTF-8. I think it matter that it's UTF-8, to judge by the
>
> if (GetDatabaseEncoding() == PG_UTF8)
>
> Block in plperl.c.
>
>
>
I cannot reproduce this. I tested with perl 5.10.1 which is the latest
reported stable release at <http://www.cpan.org/src/README.html>, on an
8.4.2 UTF8 database, and with the same Safe and Encode module versions
as above.
cheers
andrew
On Dec 21, 2009, at 9:04 PM, Andrew Dunstan wrote: > I cannot reproduce this. I tested with perl 5.10.1 which is the latest reported stable release at <http://www.cpan.org/src/README.html>,on an 8.4.2 UTF8 database, and with the same Safe and Encode module versions as above. I've replicated it all the way back to 8.0. I'd be happy to give you a login to my box. Best, David
David E. Wheeler wrote: > On Dec 21, 2009, at 9:04 PM, Andrew Dunstan wrote: > > > I cannot reproduce this. I tested with perl 5.10.1 which is the latest reported stable release at <http://www.cpan.org/src/README.html>,on an 8.4.2 UTF8 database, and with the same Safe and Encode module versions as above. > > I've replicated it all the way back to 8.0. I'd be happy to give you a login to my box. If a trivial plperl function can crash the server this is surely worth some research. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.