From 273986bf0d39e5166eb15ba42ebff4803e23a688 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 13 Nov 2012 14:44:28 -0500
Subject: [PATCH] Fix memory leaks in record_out() and record_send().
record_out() leaks memory: it fails to free the strings returned by the
per-column output functions, and also is careless about detoasted values.
This results in a query-lifespan memory leakage when returning composite
values to the client, because printtup() runs the output functions in the
query-lifespan memory context. Fix it to handle these issues the same way
printtup() does. Also fix a similar leakage in record_send().
(At some point we might want to try to run output functions in
shorter-lived memory contexts, so that we don't need a zero-leakage policy
for them. But that would be a significantly more invasive patch, which
doesn't seem like material for back-patching.)
In passing, use appendStringInfoCharMacro instead of appendStringInfoChar
in the innermost data-copying loop of record_out, to try to shave a few
cycles from this function's runtime.
Per trouble report from Carlos Henrique Reimer. Back-patch to all
supported versions.
---
src/backend/utils/adt/rowtypes.c | 52 ++++++++++++++++++++++++--------
1 file changed, 40 insertions(+), 12 deletions(-)
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index 13e574d4e82..d4ed7d0ca06 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -32,6 +32,7 @@ typedef struct ColumnIOData
Oid column_type;
Oid typiofunc;
Oid typioparam;
+ bool typisvarlena;
FmgrInfo proc;
} ColumnIOData;
@@ -364,6 +365,7 @@ record_out(PG_FUNCTION_ARGS)
{
ColumnIOData *column_info = &my_extra->columns[i];
Oid column_type = tupdesc->attrs[i]->atttypid;
+ Datum attr;
char *value;
char *tmp;
bool nq;
@@ -387,17 +389,24 @@ record_out(PG_FUNCTION_ARGS)
*/
if (column_info->column_type != column_type)
{
- bool typIsVarlena;
-
getTypeOutputInfo(column_type,
&column_info->typiofunc,
- &typIsVarlena);
+ &column_info->typisvarlena);
fmgr_info_cxt(column_info->typiofunc, &column_info->proc,
fcinfo->flinfo->fn_mcxt);
column_info->column_type = column_type;
}
- value = OutputFunctionCall(&column_info->proc, values[i]);
+ /*
+ * If we have a toasted datum, forcibly detoast it here to avoid
+ * memory leakage inside the type's output routine.
+ */
+ if (column_info->typisvarlena)
+ attr = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
+ else
+ attr = values[i];
+
+ value = OutputFunctionCall(&column_info->proc, attr);
/* Detect whether we need double quotes for this value */
nq = (value[0] == '\0'); /* force quotes for empty string */
@@ -416,17 +425,23 @@ record_out(PG_FUNCTION_ARGS)
/* And emit the string */
if (nq)
- appendStringInfoChar(&buf, '"');
+ appendStringInfoCharMacro(&buf, '"');
for (tmp = value; *tmp; tmp++)
{
char ch = *tmp;
if (ch == '"' || ch == '\\')
- appendStringInfoChar(&buf, ch);
- appendStringInfoChar(&buf, ch);
+ appendStringInfoCharMacro(&buf, ch);
+ appendStringInfoCharMacro(&buf, ch);
}
if (nq)
- appendStringInfoChar(&buf, '"');
+ appendStringInfoCharMacro(&buf, '"');
+
+ pfree(value);
+
+ /* Clean up detoasted copy, if any */
+ if (DatumGetPointer(attr) != DatumGetPointer(values[i]))
+ pfree(DatumGetPointer(attr));
}
appendStringInfoChar(&buf, ')');
@@ -714,6 +729,7 @@ record_send(PG_FUNCTION_ARGS)
{
ColumnIOData *column_info = &my_extra->columns[i];
Oid column_type = tupdesc->attrs[i]->atttypid;
+ Datum attr;
bytea *outputbytes;
/* Ignore dropped columns in datatype */
@@ -734,23 +750,35 @@ record_send(PG_FUNCTION_ARGS)
*/
if (column_info->column_type != column_type)
{
- bool typIsVarlena;
-
getTypeBinaryOutputInfo(column_type,
&column_info->typiofunc,
- &typIsVarlena);
+ &column_info->typisvarlena);
fmgr_info_cxt(column_info->typiofunc, &column_info->proc,
fcinfo->flinfo->fn_mcxt);
column_info->column_type = column_type;
}
- outputbytes = SendFunctionCall(&column_info->proc, values[i]);
+ /*
+ * If we have a toasted datum, forcibly detoast it here to avoid
+ * memory leakage inside the type's output routine.
+ */
+ if (column_info->typisvarlena)
+ attr = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
+ else
+ attr = values[i];
+
+ outputbytes = SendFunctionCall(&column_info->proc, attr);
/* We assume the result will not have been toasted */
pq_sendint(&buf, VARSIZE(outputbytes) - VARHDRSZ, 4);
pq_sendbytes(&buf, VARDATA(outputbytes),
VARSIZE(outputbytes) - VARHDRSZ);
+
pfree(outputbytes);
+
+ /* Clean up detoasted copy, if any */
+ if (DatumGetPointer(attr) != DatumGetPointer(values[i]))
+ pfree(DatumGetPointer(attr));
}
pfree(values);
--
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