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 52d41658c1f32e39f6d478fd3cfe5741b3f59c85..7fbce907dbab91fed93e51310daf4533feb3f0c8 100644 (file)
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -842,6 +842,8 @@ pqSaveWriteError(PGconn *conn)
  * using whatever is in conn->errorMessage.  In any case, clear the async
  * result storage, and update our notion of how much error text has been
  * returned to the application.
+ *
+ * Note that in no case (not even OOM) do we return NULL.
  */
 PGresult *
 pqPrepareAsyncResult(PGconn *conn)
@@ -2138,7 +2140,7 @@ PQgetResult(PGconn *conn)
                                 * (In other words: we don't return a NULL after a pipeline
                                 * sync.)
                                 */
-                               if (res && res->resultStatus == PGRES_PIPELINE_SYNC)
+                               if (res->resultStatus == PGRES_PIPELINE_SYNC)
                                        pqPipelineProcessQueue(conn);
                        }
                        else