From ab8ddaa7ca3899b734ea7f56074d0151a7d9a4df Mon Sep 17 00:00:00 2001
From: Takashi Matsuoka <matsujirushi@live.jp>
Date: Fri, 14 May 2021 18:06:39 +0900
Subject: [PATCH] Fix subscribe for large payloads

---
 .../MQTTClient/src/MQTTClient.h               | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/paho_mqtt_embedded_c/MQTTClient/src/MQTTClient.h b/paho_mqtt_embedded_c/MQTTClient/src/MQTTClient.h
index e15a2fa..7467237 100644
--- a/paho_mqtt_embedded_c/MQTTClient/src/MQTTClient.h
+++ b/paho_mqtt_embedded_c/MQTTClient/src/MQTTClient.h
@@ -473,10 +473,22 @@ int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::readPacket(Timer& tim
     }
 
     /* 3. read the rest of the buffer using a callback to supply the rest of the data */
-    if (rem_len > 0 && (ipstack.read(readbuf + len, rem_len, timer.left_ms()) != rem_len))
+    while (rem_len > 0)
     {
-        rc = FAILURE;
-        goto exit;
+        const int read_len = ipstack.read(readbuf + len, rem_len, timer.left_ms());
+        if (read_len < 0 || rem_len < read_len) // Error
+        {
+            rc = FAILURE;
+            goto exit;
+        }
+        if (read_len == 0)                      // Time out
+        {
+            rc = 0;
+            goto exit;
+        }
+
+        len += read_len;
+        rem_len -= read_len;
     }
 
     header.byte = readbuf[0];
@@ -581,7 +593,6 @@ int MQTT::Client<Network, Timer, a, b>::yield(unsigned long timeout_ms)
     return rc;
 }
 
-
 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b>
 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::cycle(Timer& timer)
 {