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;
+       }
+}