Revise init_sequence so that it doesn't leak memory if the requested

sequence doesn't exist.

diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 228aaba7990b3e81d82ef616991013621d29a618..ad81df2316766962128255a0451e1cb12941473f 100644 (file)
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -388,57 +388,57 @@ static SeqTable
 init_sequence(char *caller, char *name)
 {
    SeqTable    elm,
-               priv = (SeqTable) NULL;
-   SeqTable    temp;
+               prev = (SeqTable) NULL;
+   Relation    seqrel;
 
-   for (elm = seqtab; elm != (SeqTable) NULL;)
+   /* Look to see if we already have a seqtable entry for name */
+   for (elm = seqtab; elm != (SeqTable) NULL; elm = elm->next)
    {
        if (strcmp(elm->name, name) == 0)
            break;
-       priv = elm;
-       elm = elm->next;
+       prev = elm;
    }
 
-   if (elm == (SeqTable) NULL) /* not found */
-   {
-       temp = (SeqTable) malloc(sizeof(SeqTableData));
-       temp->name = malloc(strlen(name) + 1);
-       strcpy(temp->name, name);
-       temp->rel = (Relation) NULL;
-       temp->cached = temp->last = temp->increment = 0;
-       temp->next = (SeqTable) NULL;
-   }
-   else
-/* found */
-   {
-       if (elm->rel != (Relation) NULL)        /* already opened */
-           return elm;
-       temp = elm;
-   }
+   /* If so, and if it's already been opened in this xact, just return it */
+   if (elm != (SeqTable) NULL && elm->rel != (Relation) NULL)
+       return elm;
 
-   temp->rel = heap_openr(name, AccessShareLock);
-
-   if (temp->rel->rd_rel->relkind != RELKIND_SEQUENCE)
+   /* Else open and check it */
+   seqrel = heap_openr(name, AccessShareLock);
+   if (seqrel->rd_rel->relkind != RELKIND_SEQUENCE)
        elog(ERROR, "%s.%s: %s is not sequence !", name, caller, name);
 
-   if (elm != (SeqTable) NULL) /* we opened sequence from our */
-   {                           /* SeqTable - check relid ! */
-       if (RelationGetRelid(elm->rel) != elm->relid)
+   if (elm != (SeqTable) NULL)
+   {
+       /* We are using a seqtable entry left over from a previous xact;
+        * must check for relid change.
+        */
+       elm->rel = seqrel;
+       if (RelationGetRelid(seqrel) != elm->relid)
        {
            elog(NOTICE, "%s.%s: sequence was re-created",
                 name, caller, name);
+           elm->relid = RelationGetRelid(seqrel);
            elm->cached = elm->last = elm->increment = 0;
-           elm->relid = RelationGetRelid(elm->rel);
        }
    }
    else
    {
-       elm = temp;
-       elm->relid = RelationGetRelid(elm->rel);
+       /* Time to make a new seqtable entry.  These entries live as long
+        * as the backend does, so we use plain malloc for them.
+        */
+       elm = (SeqTable) malloc(sizeof(SeqTableData));
+       elm->name = malloc(strlen(name) + 1);
+       strcpy(elm->name, name);
+       elm->rel = seqrel;
+       elm->relid = RelationGetRelid(seqrel);
+       elm->cached = elm->last = elm->increment = 0;
+       elm->next = (SeqTable) NULL;
+
        if (seqtab == (SeqTable) NULL)
            seqtab = elm;
        else
-           priv->next = elm;
+           prev->next = elm;
    }
 
    return elm;