Problem returning strings with pgsql 8.3.x - Mailing list pgsql-hackers

Having posted this to -general [1] per -hackers list instructions [2]
to try elsewhere first, and waited (not very long, I admit) in vain
for a response, I'm posting this to -hackers now. My apologies if my
impatience in that regard annoys.

While developing PL/LOLCODE, I've found something wrong with returning
strings from LOLCODE functions using 8.3.0 or greater. Using 8.4beta
from a few days ago, for instance, a function that should return "test
string" returns
"\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F\x7F" in
pgsql (sometimes the number of \x7F characters varies). In 8.2.4 it
works fine.

Here's the code involved, from pl_lolcode_call_handler, the call
handler function for PL/LOLCODE. First, the bit that finds the
FmgrInfo structure and typioparam for the result type:
       procTup = SearchSysCache(PROCOID,
ObjectIdGetDatum(fcinfo->flinfo->fn_oid), 0, 0, 0);       if (!HeapTupleIsValid(procTup)) elog(ERROR, "Cache lookup
failed for procedure %u", fcinfo->flinfo->fn_oid);       procStruct = (Form_pg_proc) GETSTRUCT(procTup);
       typeTup = SearchSysCache(TYPEOID,
ObjectIdGetDatum(procStruct->prorettype), 0, 0, 0);       if (!HeapTupleIsValid(typeTup)) elog(ERROR, "Cache lookup
failed for type %u", procStruct->prorettype);       typeStruct = (Form_pg_type) GETSTRUCT(typeTup);
       resultTypeIOParam = getTypeIOParam(typeTup);       fmgr_info_cxt(typeStruct->typinput, &flinfo,
TopMemoryContext); /*CurTransactionContext); */       ReleaseSysCache(typeTup);

Here's the code that converts the return value into a Datum later on
in the function:
       if (returnTypeOID != VOIDOID) {               if (returnVal != NULL) {                       if (returnVal->type
==ident_NOOB)                               fcinfo->isnull = true;                       else  {
      SPI_push();                               if (returnTypeOID == BOOLOID)
retval=
 
InputFunctionCall(&flinfo, lolVarGetTroof(returnVal) == lolWIN ?
"TRUE" : "FALSE", resultTypeIOParam, -1);                               else {                                       /*
elog(NOTICE,
lolVarGetString(returnVal, true)); */                                       retval =
InputFunctionCall(&flinfo, lolVarGetString(returnVal, true),resultTypeIOParam, -1);                               }
                         SPI_pop();                       }               }               else {
fcinfo->isnull= true;               }       }
 
       SPI_finish();       /* elog(NOTICE, "PL/LOLCODE ending"); */
       return retval;

returnVal is an instance of the struct PL/LOLCODE uses to store its
variables. The key line in this case is the one after the
commented-out call to elog. retval is a Datum type. lolVarGetString()
returns the string value the returnVal struct represents -- I'm
certain of that thanks to gdb and other testing. All other data types
PL/LOLCODE knows about internally seem to return just fine. I'm fairly
certain I'm screwing up memory somewhere, but I can't see what I've
done wrong.

I'm glad to provide further details, but those included above are all
the ones I thought were relevant. Thanks in advance for any help you
can provide.
- Josh / eggyknap

[1] http://archives.postgresql.org/pgsql-general/2008-05/msg00311.php
[2] http://archives.postgresql.org/pgsql-hackers/