From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Qiyu Hu <qiyuh@google.com>
Date: Wed, 13 Jun 2018 08:08:17 -0700
Subject: [PATCH] Fix reliable write.

We cannot simply assume the write is terminated in reliable write. When
the reliable write value is longer than MTU allows, the current
implementation can only send whatever MTU allows and naively set the
status to GATT_SUCCESS, in the name of "application should verify handle
offset and value are matched or not". That's why MTU negotiation is a
workaround as people mention in b/37031096, which just fits all the write
value into a single request.

This also blocks our test on CtsVerifier.

Bug: 37031096
Test: Manual test and confirm that we don't simply send partial value
Change-Id: I907877608f4672f24c002e630e58bf9133937a5e
---
 stack/gatt/gatt_cl.cc | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/stack/gatt/gatt_cl.cc b/stack/gatt/gatt_cl.cc
index f8d5bab92..16a7171f6 100644
--- a/stack/gatt/gatt_cl.cc
+++ b/stack/gatt/gatt_cl.cc
@@ -297,7 +297,7 @@ void gatt_send_queue_write_cancel(tGATT_TCB& tcb, tGATT_CLCB* p_clcb,
 bool gatt_check_write_long_terminate(tGATT_TCB& tcb, tGATT_CLCB* p_clcb,
                                      tGATT_VALUE* p_rsp_value) {
   tGATT_VALUE* p_attr = (tGATT_VALUE*)p_clcb->p_attr_buf;
-  bool exec = false;
+  bool terminate = false;
   tGATT_EXEC_FLAG flag = GATT_PREP_WRITE_EXEC;
 
   VLOG(1) << __func__;
@@ -310,19 +310,18 @@ bool gatt_check_write_long_terminate(tGATT_TCB& tcb, tGATT_CLCB* p_clcb,
       /* data does not match    */
       p_clcb->status = GATT_ERROR;
       flag = GATT_PREP_WRITE_CANCEL;
-      exec = true;
+      terminate = true;
     } else /* response checking is good */
     {
       p_clcb->status = GATT_SUCCESS;
       /* update write offset and check if end of attribute value */
-      if ((p_attr->offset += p_rsp_value->len) >= p_attr->len) exec = true;
+      if ((p_attr->offset += p_rsp_value->len) >= p_attr->len) terminate = true;
     }
   }
-  if (exec) {
+  if (terminate && p_clcb->op_subtype != GATT_WRITE_PREPARE) {
     gatt_send_queue_write_cancel(tcb, p_clcb, flag);
-    return true;
   }
-  return false;
+  return terminate;
 }
 
 /** Send prepare write */
@@ -587,15 +586,15 @@ void gatt_process_prep_write_rsp(tGATT_TCB& tcb, tGATT_CLCB* p_clcb,
 
   memcpy(value.value, p, value.len);
 
+  if (!gatt_check_write_long_terminate(tcb, p_clcb, &value)) {
+    gatt_send_prepare_write(tcb, p_clcb);
+    return;
+  }
+
   if (p_clcb->op_subtype == GATT_WRITE_PREPARE) {
-    p_clcb->status = GATT_SUCCESS;
     /* application should verify handle offset
        and value are matched or not */
-
     gatt_end_operation(p_clcb, p_clcb->status, &value);
-  } else if (p_clcb->op_subtype == GATT_WRITE) {
-    if (!gatt_check_write_long_terminate(tcb, p_clcb, &value))
-      gatt_send_prepare_write(tcb, p_clcb);
   }
 }
 /*******************************************************************************
