MonetDB: Oct2020 - Protect against null pointers

[Pedro Ferreira]

Changeset: ac14e3e26f88 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=ac14e3e26f88
Modified Files:
        sql/server/sql_qc.c
Branch: Oct2020
Log Message:

Protect against null pointers


diffs (104 lines):

diff --git a/sql/server/sql_qc.c b/sql/server/sql_qc.c
--- a/sql/server/sql_qc.c
+++ b/sql/server/sql_qc.c
@@ -42,16 +42,18 @@ qc_delete(qc *cache, cq *q)
 {
        cq *n, *p = NULL;
 
-       for (n = cache->q; n; p = n, n = n->next) {
-               if (n == q) {
-                       if (p) {
-                               p->next = q->next;
-                       } else {
-                               cache->q = q->next;
+       if (cache) {
+               for (n = cache->q; n; p = n, n = n->next) {
+                       if (n == q) {
+                               if (p) {
+                                       p->next = q->next;
+                               } else {
+                                       cache->q = q->next;
+                               }
+                               cq_delete(cache->clientid, q);
+                               cache->nr--;
+                               break;
                        }
-                       cq_delete(cache->clientid, q);
-                       cache->nr--;
-                       break;
                }
        }
 }
@@ -61,24 +63,29 @@ qc_clean(qc *cache)
 {
        cq *n, *p = NULL;
 
-       for (n = cache->q; n; ) {
-               p = n->next;
-               cq_delete(cache->clientid, n);
-               cache->nr--;
-               n = p;
+       if (cache) {
+               for (n = cache->q; n; ) {
+                       p = n->next;
+                       cq_delete(cache->clientid, n);
+                       cache->nr--;
+                       n = p;
+               }
+               cache->q = NULL;
        }
-       cache->q = NULL;
 }
 
 void
 qc_destroy(qc *cache)
 {
        cq *q, *n;
-       for (q = cache->q; q; q = n) {
-               n = q->next;
 
-               cq_delete(cache->clientid, q);
-               cache->nr--;
+       if (cache) {
+               for (q = cache->q; q; q = n) {
+                       n = q->next;
+
+                       cq_delete(cache->clientid, q);
+                       cache->nr--;
+               }
        }
 }
 
@@ -87,10 +94,12 @@ qc_find(qc *cache, int id)
 {
        cq *q;
 
-       for (q = cache->q; q; q = q->next) {
-               if (q->id == id) {
-                       q->count++;
-                       return q;
+       if (cache) {
+               for (q = cache->q; q; q = q->next) {
+                       if (q->id == id) {
+                               q->count++;
+                               return q;
+                       }
                }
        }
        return NULL;
@@ -104,7 +113,7 @@ qc_insert(qc *cache, sql_allocator *sa, 
        cq *n = SA_ZNEW(sa, cq);
        list *res = NULL;
 
-       if (!n || !f)
+       if (!n || !f || !cache)
                return NULL;
        n->id = cache->id++;
        cache->nr++;
@@ -158,5 +167,5 @@ qc_insert(qc *cache, sql_allocator *sa, 
 int
 qc_size(qc *cache)
 {
-       return cache->nr;
+       return cache ? cache->nr : 0;
 }
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