Merge pull request #8350 from mirelachirica/at_consume_to_tag_fix

Cellular: Fix for AT handler consume to tag

Author: Cruz Monrreal

UNITTESTS/features/cellular/framework/AT/athandler/athandlertest.cpp

@@ -1063,6 +1063,27 @@ TEST_F(TestATHandler, test_ATHandler_consume_to_stop_tag)
 
     ATHandler at(&fh1, que, 0, ",");
     EXPECT_TRUE(at.consume_to_stop_tag());
+
+    at.clear_error();
+    char table1[] = "\r\n\r\r\r\nOOK\r\n";
+    at.flush();
+    filehandle_stub_table = table1;
+    filehandle_stub_table_pos = 0;
+    mbed_poll_stub::revents_value = POLLIN;
+    mbed_poll_stub::int_value = 1;
+    char buf1[6];
+    at.resp_start();
+    EXPECT_TRUE(at.consume_to_stop_tag());
+
+    at.clear_error();
+    char table2[] = "OKOK\r\n";
+    at.flush();
+    filehandle_stub_table = table2;
+    filehandle_stub_table_pos = 0;
+    mbed_poll_stub::revents_value = POLLIN;
+    mbed_poll_stub::int_value = 1;
+    char buf2[6];
+    EXPECT_TRUE(at.consume_to_stop_tag());
 }
 
 TEST_F(TestATHandler, test_ATHandler_set_debug)

features/cellular/framework/AT/ATHandler.cpp

@@ -943,16 +943,16 @@ bool ATHandler::consume_to_tag(const char *tag, bool consume_tag)
         int c = get_char();
         if (c == -1) {
             break;
-        } else if (c == tag[match_pos]) {
+        // compares c against tag at current position and if this match fails
+        // compares c against tag[0] and also resets match_pos to 0
+        } else if (c == tag[match_pos] || ((match_pos = 1) && (c == tag[--match_pos]))) {
             match_pos++;
             if (match_pos == strlen(tag)) {
                 if (!consume_tag) {
                     _recv_pos -= strlen(tag);
                 }
                 return true;
             }
-        } else if (match_pos) {
-            match_pos = 0;
         }
     }
     tr_debug("consume_to_tag not found");