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Commit68a8ea6

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Fix memory leaks in record_out() and record_send().
record_out() leaks memory: it fails to free the strings returned by theper-column output functions, and also is careless about detoasted values.This results in a query-lifespan memory leakage when returning compositevalues to the client, because printtup() runs the output functions in thequery-lifespan memory context. Fix it to handle these issues the same wayprinttup() does. Also fix a similar leakage in record_send().(At some point we might want to try to run output functions inshorter-lived memory contexts, so that we don't need a zero-leakage policyfor them. But that would be a significantly more invasive patch, whichdoesn't seem like material for back-patching.)In passing, use appendStringInfoCharMacro instead of appendStringInfoCharin the innermost data-copying loop of record_out, to try to shave a fewcycles from this function's runtime.Per trouble report from Carlos Henrique Reimer. Back-patch to allsupported versions.
1 parentd0d58f7 commit68a8ea6

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+40
-12
lines changed

1 file changed

+40
-12
lines changed

‎src/backend/utils/adt/rowtypes.c

Lines changed: 40 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,7 @@ typedef struct ColumnIOData
3131
Oidcolumn_type;
3232
Oidtypiofunc;
3333
Oidtypioparam;
34+
booltypisvarlena;
3435
FmgrInfoproc;
3536
}ColumnIOData;
3637

@@ -363,6 +364,7 @@ record_out(PG_FUNCTION_ARGS)
363364
{
364365
ColumnIOData*column_info=&my_extra->columns[i];
365366
Oidcolumn_type=tupdesc->attrs[i]->atttypid;
367+
Datumattr;
366368
char*value;
367369
char*tmp;
368370
boolnq;
@@ -386,17 +388,24 @@ record_out(PG_FUNCTION_ARGS)
386388
*/
387389
if (column_info->column_type!=column_type)
388390
{
389-
booltypIsVarlena;
390-
391391
getTypeOutputInfo(column_type,
392392
&column_info->typiofunc,
393-
&typIsVarlena);
393+
&column_info->typisvarlena);
394394
fmgr_info_cxt(column_info->typiofunc,&column_info->proc,
395395
fcinfo->flinfo->fn_mcxt);
396396
column_info->column_type=column_type;
397397
}
398398

399-
value=OutputFunctionCall(&column_info->proc,values[i]);
399+
/*
400+
* If we have a toasted datum, forcibly detoast it here to avoid
401+
* memory leakage inside the type's output routine.
402+
*/
403+
if (column_info->typisvarlena)
404+
attr=PointerGetDatum(PG_DETOAST_DATUM(values[i]));
405+
else
406+
attr=values[i];
407+
408+
value=OutputFunctionCall(&column_info->proc,attr);
400409

401410
/* Detect whether we need double quotes for this value */
402411
nq= (value[0]=='\0');/* force quotes for empty string */
@@ -415,17 +424,23 @@ record_out(PG_FUNCTION_ARGS)
415424

416425
/* And emit the string */
417426
if (nq)
418-
appendStringInfoChar(&buf,'"');
427+
appendStringInfoCharMacro(&buf,'"');
419428
for (tmp=value;*tmp;tmp++)
420429
{
421430
charch=*tmp;
422431

423432
if (ch=='"'||ch=='\\')
424-
appendStringInfoChar(&buf,ch);
425-
appendStringInfoChar(&buf,ch);
433+
appendStringInfoCharMacro(&buf,ch);
434+
appendStringInfoCharMacro(&buf,ch);
426435
}
427436
if (nq)
428-
appendStringInfoChar(&buf,'"');
437+
appendStringInfoCharMacro(&buf,'"');
438+
439+
pfree(value);
440+
441+
/* Clean up detoasted copy, if any */
442+
if (DatumGetPointer(attr)!=DatumGetPointer(values[i]))
443+
pfree(DatumGetPointer(attr));
429444
}
430445

431446
appendStringInfoChar(&buf,')');
@@ -713,6 +728,7 @@ record_send(PG_FUNCTION_ARGS)
713728
{
714729
ColumnIOData*column_info=&my_extra->columns[i];
715730
Oidcolumn_type=tupdesc->attrs[i]->atttypid;
731+
Datumattr;
716732
bytea*outputbytes;
717733

718734
/* Ignore dropped columns in datatype */
@@ -733,23 +749,35 @@ record_send(PG_FUNCTION_ARGS)
733749
*/
734750
if (column_info->column_type!=column_type)
735751
{
736-
booltypIsVarlena;
737-
738752
getTypeBinaryOutputInfo(column_type,
739753
&column_info->typiofunc,
740-
&typIsVarlena);
754+
&column_info->typisvarlena);
741755
fmgr_info_cxt(column_info->typiofunc,&column_info->proc,
742756
fcinfo->flinfo->fn_mcxt);
743757
column_info->column_type=column_type;
744758
}
745759

746-
outputbytes=SendFunctionCall(&column_info->proc,values[i]);
760+
/*
761+
* If we have a toasted datum, forcibly detoast it here to avoid
762+
* memory leakage inside the type's output routine.
763+
*/
764+
if (column_info->typisvarlena)
765+
attr=PointerGetDatum(PG_DETOAST_DATUM(values[i]));
766+
else
767+
attr=values[i];
768+
769+
outputbytes=SendFunctionCall(&column_info->proc,attr);
747770

748771
/* We assume the result will not have been toasted */
749772
pq_sendint(&buf,VARSIZE(outputbytes)-VARHDRSZ,4);
750773
pq_sendbytes(&buf,VARDATA(outputbytes),
751774
VARSIZE(outputbytes)-VARHDRSZ);
775+
752776
pfree(outputbytes);
777+
778+
/* Clean up detoasted copy, if any */
779+
if (DatumGetPointer(attr)!=DatumGetPointer(values[i]))
780+
pfree(DatumGetPointer(attr));
753781
}
754782

755783
pfree(values);

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