Fix ALTER TABLE regression in avrorouter

The avrorouter failed to detect ALTER TABLE statements which caused a
regression. Extended the alter table tests to parse the JSON for more
strict validation of test results.

maxscale-system-test/avro.cpp

@@ -7,7 +7,6 @@
  */
 
 
-#include <iostream>
 #include "testconnections.h"
 #include "maxadmin_operations.h"
 #include "sql_t1.h"
@@ -49,8 +48,6 @@ int main(int argc, char *argv[])
     sleep(10);
     test.set_timeout(120);
 
-    char * avro_check = test.ssh_maxscale_output(true,
-                                                 "maxavrocheck -vv /var/lib/maxscale/avro/test.t1.000001.avro | grep \"{\"");
     char * output = test.ssh_maxscale_output(true, "maxavrocheck -d /var/lib/maxscale/avro/test.t1.000001.avro");
 
     std::istringstream iss;

maxscale-system-test/avro_alter.cpp

@@ -3,7 +3,9 @@
  */
 
 #include "testconnections.h"
+#include <jansson.h>
 #include <sstream>
+#include <iostream>
 
 int main(int argc, char *argv[])
 {
@@ -43,11 +45,23 @@ int main(int argc, char *argv[])
     for (int i = 1; i <=5; i++)
     {
         std::stringstream cmd;
-        cmd << "maxavrocheck -d /var/lib/maxscale/avro/test.t1.00000" << i << ".avro|wc -l";
+        cmd << "maxavrocheck -d /var/lib/maxscale/avro/test.t1.00000" << i << ".avro";
         char* rows = test.ssh_maxscale_output(true, cmd.str().c_str());
-        int nrows = atoi(rows);
+        int nrows = 0;
+        std::istringstream iss;
+        iss.str(rows);
+
+        for (std::string line; std::getline(iss, line);)
+        {
+            json_error_t err;
+            json_t* json = json_loads(line.c_str(), 0, &err);
+            test.add_result(json == NULL, "Failed to parse JSON: %s", line.c_str());
+            json_decref(json);
+            nrows++;
+        }
+
+        test.add_result(nrows != 1, "Expected 1 line in file number %d, got %d: %s", i, nrows, rows);
         free(rows);
-        test.add_result(nrows != 1, "Expected 1 line in file number %d, got %d", i, nrows);
     }
 
     execute_query(test.repl->nodes[0], "DROP TABLE test.t1;RESET MASTER");

server/modules/routing/avrorouter/avro_file.c

@@ -1055,14 +1055,14 @@ void handle_query_event(AVRO_INSTANCE *router, REP_HEADER *hdr, int *pending_tra
 
         bool combine = (strnlen(db, 1) && strchr(ident, '.') == NULL);
 
-        size_t len = strlen(ident) + 1; // + 1 for the NULL
+        size_t ident_len = strlen(ident) + 1; // + 1 for the NULL
 
         if (combine)
         {
-            len += (strlen(db) + 1); // + 1 for the "."
+            ident_len += (strlen(db) + 1); // + 1 for the "."
         }
 
-        char full_ident[len];
+        char full_ident[ident_len];
         full_ident[0] = 0; // Set full_ident to "".
 
         if (combine)