Cellular: ATHandler yield to wait review fixes

features/cellular/framework/AT/ATHandler.cpp

@@ -17,6 +17,7 @@
 
 #include <ctype.h>
 #include <stdio.h>
+#include <limits.h>
 #include "ATHandler.h"
 #include "mbed_poll.h"
 #include "FileHandle.h"
@@ -290,8 +291,7 @@ void ATHandler::process_oob()
                     break; // we have nothing to read anymore
                 }
                 _start_time = rtos::Kernel::get_ms_count(); // time to process next (potential) URC
-            } else if (mem_str(_recv_buff, _recv_len, CRLF, CRLF_LENGTH)) {
-                // If no match found, look for CRLF and consume everything up to CRLF
+            } else if (mem_str(_recv_buff, _recv_len, CRLF, CRLF_LENGTH)) { // If no match found, look for CRLF and consume everything up to CRLF
                 consume_to_tag(CRLF, true);
             } else {
                 if (!fill_buffer()) {
@@ -335,7 +335,7 @@ void ATHandler::rewind_buffer()
     }
 }
 
-bool ATHandler::fill_buffer()
+bool ATHandler::fill_buffer(bool wait_for_timeout)
 {
     tr_debug("%s", __func__);
     // Reset buffer when full
@@ -343,8 +343,20 @@ bool ATHandler::fill_buffer()
         reset_buffer();
     }
 
-    int timeout = (_start_time + _at_timeout) - rtos::Kernel::get_ms_count();
-    if (timeout >= 0) {
+    int timeout;
+    if (wait_for_timeout) {
+        uint64_t now = rtos::Kernel::get_ms_count();
+        if (now >= _start_time + _at_timeout) {
+            timeout = 0;
+        } else if ( _start_time + _at_timeout - now > INT_MAX) {
+            timeout = INT_MAX;
+        } else {
+            timeout = _start_time + _at_timeout - now;
+        }
+    } else {
+        timeout = 0;
+    }
+
     pollfh fhs;
     fhs.fh = _fileHandle;
     fhs.events = POLLIN;
@@ -356,9 +368,10 @@ bool ATHandler::fill_buffer()
             return true;
         }
     }
-    }
 
+    if (wait_for_timeout) {
         set_error(NSAPI_ERROR_DEVICE_ERROR);
+    }
 
     return false;
 }
@@ -800,17 +813,11 @@ void ATHandler::resp_start(const char *prefix, bool stop)
 
     // Try get as much data as possible
     rewind_buffer();
-    if (!fill_buffer()) {
-        tr_error("fill failed %s", prefix);
-        return;
-    }
+    (void)fill_buffer(false);
 
     if (prefix) {
-        if ((strlen(prefix) < sizeof(_info_resp_prefix))) {
-            strcpy(_info_resp_prefix, prefix);
-        } else {
-            MBED_ASSERT(0);
-        }
+        MBED_ASSERT(strlen(prefix) < BUFF_SIZE);
+        strcpy(_info_resp_prefix, prefix); // copy prefix so we can later use it without having to provide again for info_resp
     }
 
     set_scope(RespType);
@@ -1133,9 +1140,8 @@ bool ATHandler::check_cmd_send()
 
 void ATHandler::flush()
 {
-    while (_fileHandle->readable()) {
     reset_buffer();
-        (void) fill_buffer();
-    }
+    while (fill_buffer(false)) {
         reset_buffer();
     }
+}

features/cellular/framework/AT/ATHandler.h

@@ -432,7 +432,7 @@ private:
     void rewind_buffer();
     // Reads from serial to receiving buffer.
     // Returns true on successful read OR false on timeout.
-    bool fill_buffer();
+    bool fill_buffer(bool wait_for_timeout = true);
 
     void set_tag(tag_t* tag_dest, const char *tag_seq);