EXPLAIN VERBOSE had a very high probability of triggering

a backend core dump, because it was concatenating a potentially long
string onto another string that didn't necessarily have enough room.
Shame, shame.

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 1b861c96204944ccb93fc8cbb986c2fffff8d21e..f7bb3e5ec44155f1fd374ee6a715ef9a48e5bfb4 100644 (file)
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.25 1998/10/21 16:21:20 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.26 1998/11/08 19:38:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -38,6 +38,7 @@ typedef struct ExplainState
 } ExplainState;
 
 static char *Explain_PlanToString(Plan *plan, ExplainState *es);
+static void printLongNotice(const char * header, const char * message);
 static void ExplainOneQuery(Query *query, bool verbose, CommandDest dest);
 
 
@@ -87,11 +88,9 @@ ExplainQuery(Query *query, bool verbose, CommandDest dest)
 static void
 ExplainOneQuery(Query *query, bool verbose, CommandDest dest)
 {
-   char       *s = NULL,
-              *s2;
+   char       *s;
    Plan       *plan;
    ExplainState *es;
-   int         len;
 
    /* plan the queries (XXX we've ignored rewrite!!) */
    plan = planner(query);
@@ -111,30 +110,25 @@ ExplainOneQuery(Query *query, bool verbose, CommandDest dest)
    es->rtable = query->rtable;
 
    if (es->printNodes)
+   {
        s = nodeToString(plan);
+       if (s)
+       {
+           printLongNotice("QUERY DUMP:\n\n", s);
+           pfree(s);
+       }
+   }
 
    if (es->printCost)
    {
-       s2 = Explain_PlanToString(plan, es);
-       if (s == NULL)
-           s = s2;
-       else
+       s = Explain_PlanToString(plan, es);
+       if (s)
        {
-           strcat(s, "\n\n");
-           strcat(s, s2);
+           printLongNotice("QUERY PLAN:\n\n", s);
+           pfree(s);
        }
    }
 
-   /* output the plan */
-   len = strlen(s);
-   elog(NOTICE, "QUERY PLAN:\n\n%.*s", ELOG_MAXLEN - 64, s);
-   len -= ELOG_MAXLEN - 64;
-   while (len > 0)
-   {
-       s += ELOG_MAXLEN - 64;
-       elog(NOTICE, "%.*s", ELOG_MAXLEN - 64, s);
-       len -= ELOG_MAXLEN - 64;
-   }
    if (es->printNodes)
        pprint(plan);           /* display in postmaster log file */
 
@@ -361,3 +355,22 @@ Explain_PlanToString(Plan *plan, ExplainState *es)
 
    return s;
 }
+
+/*
+ * Print a message that might exceed the size of the elog message buffer.
+ * This is a crock ... there shouldn't be an upper limit to what you can elog().
+ */
+static void
+printLongNotice(const char * header, const char * message)
+{
+   int     len = strlen(message);
+
+   elog(NOTICE, "%.20s%.*s", header, ELOG_MAXLEN - 64, message);
+   len -= ELOG_MAXLEN - 64;
+   while (len > 0)
+   {
+       message += ELOG_MAXLEN - 64;
+       elog(NOTICE, "%.*s", ELOG_MAXLEN - 64, message);
+       len -= ELOG_MAXLEN - 64;
+   }
+}