postgres.git / summary / log / commit / refs

commit    68a8ea6046a0583171a34269688a2bcd8d2f8f08
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Tue Nov 13 19:44:40 2012 +0000

    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 919ed9582a7..5a7baccfb10 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -31,6 +31,7 @@ typedef struct ColumnIOData
 	Oid			column_type;
 	Oid			typiofunc;
 	Oid			typioparam;
+	bool		typisvarlena;
 	FmgrInfo	proc;
 } ColumnIOData;
 
@@ -363,6 +364,7 @@ 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;
@@ -386,17 +388,24 @@ 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 */
@@ -415,17 +424,23 @@ 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, ')');
@@ -713,6 +728,7 @@ 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 */
@@ -733,23 +749,35 @@ 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);


[parent: d0d58f7aa949]