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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 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.
This commit is contained in:
Tom Lane 2012-11-13 14:44:56 -05:00
parent 2faab1af69
commit c027d84c81
1 changed files with 40 additions and 12 deletions
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52
src/backend/utils/adt/rowtypes.c
View File

@ -32,6 +32,7 @@ typedef struct ColumnIOData
Oid column_type;
Oid typiofunc;
Oid typioparam;
bool typisvarlena;
FmgrInfo proc;
} ColumnIOData;
@ -340,6 +341,7 @@ 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;
@ -363,17 +365,24 @@ 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 */
@ -392,17 +401,23 @@ 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, ')');
@ -690,6 +705,7 @@ 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 */
@ -710,23 +726,35 @@ 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);