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Commit273986b

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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 parentd9fad10 commit273986b

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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
@@ -32,6 +32,7 @@ typedef struct ColumnIOData
3232
Oidcolumn_type;
3333
Oidtypiofunc;
3434
Oidtypioparam;
35+
booltypisvarlena;
3536
FmgrInfoproc;
3637
}ColumnIOData;
3738

@@ -364,6 +365,7 @@ record_out(PG_FUNCTION_ARGS)
364365
{
365366
ColumnIOData*column_info=&my_extra->columns[i];
366367
Oidcolumn_type=tupdesc->attrs[i]->atttypid;
368+
Datumattr;
367369
char*value;
368370
char*tmp;
369371
boolnq;
@@ -387,17 +389,24 @@ record_out(PG_FUNCTION_ARGS)
387389
*/
388390
if (column_info->column_type!=column_type)
389391
{
390-
booltypIsVarlena;
391-
392392
getTypeOutputInfo(column_type,
393393
&column_info->typiofunc,
394-
&typIsVarlena);
394+
&column_info->typisvarlena);
395395
fmgr_info_cxt(column_info->typiofunc,&column_info->proc,
396396
fcinfo->flinfo->fn_mcxt);
397397
column_info->column_type=column_type;
398398
}
399399

400-
value=OutputFunctionCall(&column_info->proc,values[i]);
400+
/*
401+
* If we have a toasted datum, forcibly detoast it here to avoid
402+
* memory leakage inside the type's output routine.
403+
*/
404+
if (column_info->typisvarlena)
405+
attr=PointerGetDatum(PG_DETOAST_DATUM(values[i]));
406+
else
407+
attr=values[i];
408+
409+
value=OutputFunctionCall(&column_info->proc,attr);
401410

402411
/* Detect whether we need double quotes for this value */
403412
nq= (value[0]=='\0');/* force quotes for empty string */
@@ -416,17 +425,23 @@ record_out(PG_FUNCTION_ARGS)
416425

417426
/* And emit the string */
418427
if (nq)
419-
appendStringInfoChar(&buf,'"');
428+
appendStringInfoCharMacro(&buf,'"');
420429
for (tmp=value;*tmp;tmp++)
421430
{
422431
charch=*tmp;
423432

424433
if (ch=='"'||ch=='\\')
425-
appendStringInfoChar(&buf,ch);
426-
appendStringInfoChar(&buf,ch);
434+
appendStringInfoCharMacro(&buf,ch);
435+
appendStringInfoCharMacro(&buf,ch);
427436
}
428437
if (nq)
429-
appendStringInfoChar(&buf,'"');
438+
appendStringInfoCharMacro(&buf,'"');
439+
440+
pfree(value);
441+
442+
/* Clean up detoasted copy, if any */
443+
if (DatumGetPointer(attr)!=DatumGetPointer(values[i]))
444+
pfree(DatumGetPointer(attr));
430445
}
431446

432447
appendStringInfoChar(&buf,')');
@@ -714,6 +729,7 @@ record_send(PG_FUNCTION_ARGS)
714729
{
715730
ColumnIOData*column_info=&my_extra->columns[i];
716731
Oidcolumn_type=tupdesc->attrs[i]->atttypid;
732+
Datumattr;
717733
bytea*outputbytes;
718734

719735
/* Ignore dropped columns in datatype */
@@ -734,23 +750,35 @@ record_send(PG_FUNCTION_ARGS)
734750
*/
735751
if (column_info->column_type!=column_type)
736752
{
737-
booltypIsVarlena;
738-
739753
getTypeBinaryOutputInfo(column_type,
740754
&column_info->typiofunc,
741-
&typIsVarlena);
755+
&column_info->typisvarlena);
742756
fmgr_info_cxt(column_info->typiofunc,&column_info->proc,
743757
fcinfo->flinfo->fn_mcxt);
744758
column_info->column_type=column_type;
745759
}
746760

747-
outputbytes=SendFunctionCall(&column_info->proc,values[i]);
761+
/*
762+
* If we have a toasted datum, forcibly detoast it here to avoid
763+
* memory leakage inside the type's output routine.
764+
*/
765+
if (column_info->typisvarlena)
766+
attr=PointerGetDatum(PG_DETOAST_DATUM(values[i]));
767+
else
768+
attr=values[i];
769+
770+
outputbytes=SendFunctionCall(&column_info->proc,attr);
748771

749772
/* We assume the result will not have been toasted */
750773
pq_sendint(&buf,VARSIZE(outputbytes)-VARHDRSZ,4);
751774
pq_sendbytes(&buf,VARDATA(outputbytes),
752775
VARSIZE(outputbytes)-VARHDRSZ);
776+
753777
pfree(outputbytes);
778+
779+
/* Clean up detoasted copy, if any */
780+
if (DatumGetPointer(attr)!=DatumGetPointer(values[i]))
781+
pfree(DatumGetPointer(attr));
754782
}
755783

756784
pfree(values);

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