s3:registry: wrap reg_deletevalue() in a transaction

This is at the wrong layer, but if fixes a race potentially causing
data corruption by concurrent access.
(cherry picked from commit c1208c4a9c10b03579dca3bcd304709e631d3c25)

diff --git a/source3/registry/reg_api.c b/source3/registry/reg_api.c
index 660a1a4839ebd3b7449e24d04db9a8a066b90ca5..2eced2698b829ce301b8079588672b6282057f22 100644 (file)
--- a/source3/registry/reg_api.c
+++ b/source3/registry/reg_api.c
@@ -790,24 +790,50 @@ WERROR reg_deletevalue(struct registry_key *key, const char *name)
                return WERR_ACCESS_DENIED;
        }
 
-       err = fill_value_cache(key);
+       err = regdb_transaction_start();
        if (!W_ERROR_IS_OK(err)) {
+               DEBUG(0, ("reg_deletevalue: Failed to start transaction: %s\n",
+                         win_errstr(err)));
                return err;
        }
 
+       err = fill_value_cache(key);
+       if (!W_ERROR_IS_OK(err)) {
+               DEBUG(0, ("reg_deletevalue; Error filling value cache: %s\n",
+                         win_errstr(err)));
+               goto done;
+       }
+
        err = reg_value_exists(key, name);
        if (!W_ERROR_IS_OK(err)) {
-               return err;
+               goto done;
        }
 
        regval_ctr_delvalue(key->values, name);
 
        if (!store_reg_values(key->key, key->values)) {
                TALLOC_FREE(key->values);
-               return WERR_REG_IO_FAILURE;
+               err = WERR_REG_IO_FAILURE;
+               DEBUG(0, ("reg_deletevalue: store_reg_values failed\n"));
+               goto done;
        }
 
-       return WERR_OK;
+       err = WERR_OK;
+
+done:
+       if (W_ERROR_IS_OK(err)) {
+               err = regdb_transaction_commit();
+               if (!W_ERROR_IS_OK(err)) {
+                       DEBUG(0, ("reg_deletevalue: Error committing transaction: %s\n", win_errstr(err)));
+               }
+       } else {
+               WERROR err1 = regdb_transaction_cancel();
+               if (!W_ERROR_IS_OK(err1)) {
+                       DEBUG(0, ("reg_deletevalue: Error cancelling transaction: %s\n", win_errstr(err1)));
+               }
+       }
+
+       return err;
 }
 
 WERROR reg_getkeysecurity(TALLOC_CTX *mem_ctx, struct registry_key *key,