Don't test already-referenced pointer for nullness

Commit b8ba7344e9eb added in PQgetResult a derefence to a pointer
returned by pqPrepareAsyncResult(), before some other code that was
already testing that pointer for nullness.  But since commit
618c16707a6d (in Postgres 15), pqPrepareAsyncResult() doesn't ever
return NULL (a statically-allocated result is returned if OOM).  So in
branches 15 and up, we can remove the redundant pointer check with no
harm done.

However, in branch 14, pqPrepareAsyncResult() can indeed return NULL if
it runs out of memory.  Fix things there by adding a null pointer check
before dereferencing the pointer.  This should hint Coverity that the
preexisting check is not redundant but necessary.

Backpatch to 14, like b8ba7344e9eb.

Per Coverity.

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 8895f81add1771ec45b1e74bb6eec7c7bc9ba011..a1c946bccd24c919a0a35fe3773f2bd063ff2890 100644 (file)
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -2091,8 +2091,9 @@ PQgetResult(PGconn *conn)
            res = pqPrepareAsyncResult(conn);
 
            /* Advance the queue as appropriate */
-           pqCommandQueueAdvance(conn, false,
-                                 res->resultStatus == PGRES_PIPELINE_SYNC);
+           if (res)
+               pqCommandQueueAdvance(conn, false,
+                                     res->resultStatus == PGRES_PIPELINE_SYNC);
 
            if (conn->pipelineStatus != PQ_PIPELINE_OFF)
            {