From 078fb34b14eca988b89fb4e896ce7d21bd55bac6 Mon Sep 17 00:00:00 2001
From: Shreeyash Bhakare <shreeyash.bhakare@espressif.com>
Date: Fri, 22 May 2026 15:46:22 +0530
Subject: [PATCH] fix(nimble): Send Prepare Write Request before Execute Write
 in write long with zero-length data

---
 nimble/host/src/ble_gattc.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/nimble/host/src/ble_gattc.c b/nimble/host/src/ble_gattc.c
index 5a7b69ed7..b34b0dcfd 100644
--- a/nimble/host/src/ble_gattc.c
+++ b/nimble/host/src/ble_gattc.c
@@ -5088,6 +5088,21 @@ ble_gattc_write_long_tx(struct ble_gattc_proc *proc)
                         proc->write_long.attr.offset);
 
     if (write_len <= 0) {
+        if (proc->write_long.attr.offset == 0 &&
+            OS_MBUF_PKTLEN(proc->write_long.attr.om) == 0) {
+            proc->write_long.length = 0;
+            om = ble_hs_mbuf_att_pkt();
+            if (om == NULL) {
+                rc = BLE_HS_ENOMEM;
+                goto done;
+            }
+            rc = ble_att_clt_tx_prep_write(proc->conn_handle, proc->cid,
+                                           proc->write_long.attr.handle,
+                                           proc->write_long.attr.offset,
+                                           om);
+            om = NULL;
+            goto done;
+        }
         rc = ble_att_clt_tx_exec_write(proc->conn_handle, proc->cid,
                                        BLE_ATT_EXEC_WRITE_F_EXECUTE);
         goto done;
@@ -5189,6 +5204,25 @@ ble_gattc_write_long_rx_prep(struct ble_gattc_proc *proc,
     if (proc->write_long.attr.offset >=
         OS_MBUF_PKTLEN(proc->write_long.attr.om)) {
 
+        if (OS_MBUF_PKTLEN(proc->write_long.attr.om) == 0 &&
+            proc->write_long.attr.offset == 0 &&
+            proc->write_long.length == 0) {
+            if (handle != proc->write_long.attr.handle) {
+                rc = BLE_HS_EBADDATA;
+                goto err;
+            }
+            if (offset != proc->write_long.attr.offset) {
+                rc = BLE_HS_EBADDATA;
+                goto err;
+            }
+            rc = ble_att_clt_tx_exec_write(proc->conn_handle, proc->cid,
+                                           BLE_ATT_EXEC_WRITE_F_EXECUTE);
+            if (rc != 0) {
+                goto err;
+            }
+            return 0;
+        }
+
         /* Expecting a prepare write response, not an execute write
          * response.
          */