Postfix LMDB 1.0 fix

0001-Postfix-Resolve-LMDB-1.0-compatibility.patch

From c2e9644f278ff31cd664c7638d7f5672a71aab33 Mon Sep 17 00:00:00 2001
From: Christian Pfeiffer <cpfeiffer@rev-crew.info>
Date: Wed, 1 Jul 2026 19:59:03 +0200
Subject: [PATCH] Postfix: Resolve LMDB 1.0 compatibility

---
 postfix/src/util/slmdb.c | 69 ++++++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 27 deletions(-)

diff --git a/postfix/src/util/slmdb.c b/postfix/src/util/slmdb.c
index e1b8fd64c..e30aeee80 100644
--- a/postfix/src/util/slmdb.c
+++ b/postfix/src/util/slmdb.c
@@ -381,40 +381,55 @@ static int slmdb_saved_key_assign(SLMDB *slmdb, MDB_val *key_val)
 
 static int slmdb_prepare(SLMDB *slmdb)
 {
-    int     status = 0;
+    int status = 0;
 
-    /*
-     * This is called before accessing the database, or after recovery from
-     * an LMDB error. Note: this code cannot recover from errors itself.
-     * slmdb->txn is either the database open() transaction or a
-     * freshly-created bulk-mode transaction. When slmdb_prepare() commits or
-     * aborts commits a transaction, it must set slmdb->txn to null to avoid
-     * a use-after-free error in slmdb_close().
-     * 
-     * - With O_TRUNC we make a "drop" request before updating the database.
-     * 
-     * - With a bulk-mode transaction we commit when the database is closed.
-     */
     if (slmdb->open_flags & O_TRUNC) {
-	if ((status = mdb_drop(slmdb->txn, slmdb->dbi, 0)) != 0) {
-	    mdb_txn_abort(slmdb->txn);
-	    slmdb->txn = 0;
-	    return (status);
-	}
-	if ((slmdb->slmdb_flags & SLMDB_FLAG_BULK) == 0) {
-	    status = mdb_txn_commit(slmdb->txn);
-	    slmdb->txn = 0;
-	    if (status != 0)
-		return (status);
-	}
+
+        /* Drop the main DB — this dirties the transaction */
+        status = mdb_drop(slmdb->txn, slmdb->dbi, 0);
+
+        /* Regardless of success, this txn MUST be aborted */
+        mdb_txn_abort(slmdb->txn);
+        slmdb->txn = 0;
+
+        if (status != 0)
+            return status;
+
+        /*
+         * Now reopen the main DB in a fresh transaction.
+         * This replaces the old DBI handle.
+         */
+        MDB_txn *txn2;
+        status = mdb_txn_begin(slmdb->env, NULL, 0, &txn2);
+        if (status != 0)
+            return status;
+
+        status = mdb_dbi_open(txn2, NULL, 0, &slmdb->dbi);
+        if (status != 0) {
+            mdb_txn_abort(txn2);
+            return status;
+        }
+
+        /* Commit the DBI re-open unless bulk mode defers it */
+        if ((slmdb->slmdb_flags & SLMDB_FLAG_BULK) == 0) {
+            status = mdb_txn_commit(txn2);
+            if (status != 0)
+                return status;
+        } else {
+            slmdb->txn = txn2;  /* bulk mode keeps txn open */
+        }
+
     } else if ((slmdb->slmdb_flags & SLMDB_FLAG_BULK) == 0) {
-	mdb_txn_abort(slmdb->txn);
-	slmdb->txn = 0;
+        /* Normal case: abort the open transaction */
+        mdb_txn_abort(slmdb->txn);
+        slmdb->txn = 0;
     }
+
     slmdb->api_retry_count = 0;
-    return (status);
+    return status;
 }
 
+
 /* slmdb_recover - recover from LMDB errors */
 
 static int slmdb_recover(SLMDB *slmdb, int status)
-- 
2.55.0