A fix and a test case for Bug#15752 "Lost connection to MySQL server

when calling a SP from C API"

The bug was caused by lack of checks for misuse in mysql_real_query. 
A stored procedure always returns at least one result, which is the 
status of execution of the procedure itself.
This result, or so-called OK packet, is similar to a result
returned by INSERT/UPDATE/CREATE operations: it contains the overall
status of execution, the number of affected rows and the number of
warnings. The client test program attached to the bug did not read this 
result and ivnoked the next query. In turn, libmysql had no check for 
such scenario and mysql_real_query was simply trying to send that query 
without reading the pending response, thus messing up the communication
protocol.

The fix is to return an error from mysql_real_query when it's called
prior to retrieval of all pending results.


client/mysqlbinlog.cc:
  net_safe_read -> cli_safe_read
include/mysql.h:
  Remove a private function from the public header.
include/mysql_com.h:
  Remove a define that is never used.
include/sql_common.h:
  Add a declaration for cli_safe_read - a function that reads one packet
  from the server.
libmysql/libmysql.c:
  net_safe_read -> cli_safe_read
  Return CR_COMMANDS_OUT_OF_SYNC on attempt to execute a statement
  using a connection which has pending result sets.
sql-common/client.c:
  Actual fix for Bug#15752: if the server has pending result sets for
  the client, return CR_COMMANDS_OUT_OF_SYNC on attempt to execute
  another query. Similarly to the behaviour of mysql_use_result(),
  multiple result sets block the connection and must be fetched
  before it can be used for another query.
  This uncovered an error in the protocol: the server doesn't drop
  SERVER_MORE_RESULTS_EXISTS status flag upon an error, so in case of
  a multi-query like SELECT 1; SELECT syntax_error; SELECT 2; 
  the client has no way to know that the server won't ever come to 
  execution of the third query and won't return any result sets for it.
  For now, fix it in cli_safe_read, as a proper fix requires extension
  of the client-server protocol.
sql/protocol.cc:
  Remove a name that is never used.
sql/slave.cc:
  net_safe_read -> cli_safe_read
tests/mysql_client_test.c:
  Make 'query' a local variable to avoid name clash.
  Add a test case for Bug#15752 "Lost connection to MySQL server when
  calling an SP from C API"

1 files changed, 96 insertions, 2 deletions

diff --git a/tests/mysql_client_test.c b/tests/mysql_client_test.c
index 7ad902afb6c..def67e22f00 100644
--- a/tests/mysql_client_test.c
+++ b/tests/mysql_client_test.c
@@ -50,7 +50,6 @@ static unsigned int  opt_port;
 static my_bool tty_password= 0, opt_silent= 0;
 
 static MYSQL *mysql= 0;
-static char query[MAX_TEST_QUERY_LENGTH];
 static char current_db[]= "client_test_db";
 static unsigned int test_count= 0;
 static unsigned int opt_count= 0;
@@ -269,6 +268,7 @@ mysql_simple_prepare(MYSQL  *mysql, const char *query)
 static void client_connect(ulong flag)
 {
   int  rc;
+  static char query[MAX_TEST_QUERY_LENGTH];
   myheader_r("client_connect");
 
   if (!opt_silent)
@@ -326,6 +326,8 @@ static void client_connect(ulong flag)
 
 static void client_disconnect()
 {
+  static char query[MAX_TEST_QUERY_LENGTH];
+
   myheader_r("client_disconnect");
 
   if (mysql)
@@ -657,6 +659,7 @@ int my_stmt_result(const char *buff)
 static void verify_col_data(const char *table, const char *col,
                             const char *exp_data)
 {
+  static char query[MAX_TEST_QUERY_LENGTH];
   MYSQL_RES *result;
   MYSQL_ROW row;
   int       rc, field= 1;
@@ -1362,6 +1365,7 @@ static void test_prepare_insert_update()
   
   for (cur_query= testcase; *cur_query; cur_query++)
   {
+    char query[MAX_TEST_QUERY_LENGTH];
     printf("\nRunning query: %s", *cur_query);
     strmov(query, *cur_query);
     stmt= mysql_simple_prepare(mysql, query);
@@ -1396,6 +1400,7 @@ static void test_prepare_simple()
 {
   MYSQL_STMT *stmt;
   int        rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare_simple");
 
@@ -1466,6 +1471,7 @@ static void test_prepare_field_result()
   MYSQL_STMT *stmt;
   MYSQL_RES  *result;
   int        rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare_field_result");
 
@@ -1517,6 +1523,7 @@ static void test_prepare_syntax()
 {
   MYSQL_STMT *stmt;
   int        rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare_syntax");
 
@@ -1558,6 +1565,7 @@ static void test_prepare()
   my_bool    is_null[7];
   char	     llbuf[22];
   MYSQL_BIND bind[7];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare");
 
@@ -1731,6 +1739,7 @@ static void test_double_compare()
   MYSQL_RES  *result;
   MYSQL_BIND bind[3];
   ulong      length[3];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_double_compare");
 
@@ -1813,6 +1822,7 @@ static void test_null()
   uint       nData;
   MYSQL_BIND bind[2];
   my_bool    is_null[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_null");
 
@@ -1959,6 +1969,7 @@ static void test_ps_null_param()
   /* Execute several queries, all returning NULL in result. */
   for(cur_query= queries; *cur_query; cur_query++)
   {
+    char query[MAX_TEST_QUERY_LENGTH];
     strmov(query, *cur_query);
     stmt= mysql_simple_prepare(mysql, query);
     check_stmt(stmt);
@@ -1990,6 +2001,7 @@ static void test_fetch_null()
   MYSQL_BIND bind[11];
   ulong      length[11];
   my_bool    is_null[11];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_fetch_null");
 
@@ -2218,6 +2230,7 @@ static void test_select()
   int        nData= 1;
   MYSQL_BIND bind[2];
   ulong length[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_select");
 
@@ -2289,6 +2302,7 @@ static void test_ps_conj_select()
   int32      int_data;
   char       str_data[32];
   unsigned long str_length;
+  char query[MAX_TEST_QUERY_LENGTH];
   myheader("test_ps_conj_select");
 
   rc= mysql_query(mysql, "drop table if exists t1");
@@ -2346,6 +2360,7 @@ static void test_bug1115()
   MYSQL_BIND bind[1];
   ulong length[1];
   char szData[11];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_bug1115");
 
@@ -2457,6 +2472,7 @@ static void test_bug1180()
   MYSQL_BIND bind[1];
   ulong length[1];
   char szData[11];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_select_bug");
 
@@ -2547,6 +2563,7 @@ static void test_bug1644()
   int num;
   my_bool isnull;
   int rc, i;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_bug1644");
 
@@ -2646,6 +2663,7 @@ static void test_select_show()
 {
   MYSQL_STMT *stmt;
   int        rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_select_show");
 
@@ -2714,6 +2732,7 @@ static void test_simple_update()
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
   ulong      length[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_simple_update");
 
@@ -2791,6 +2810,7 @@ static void test_long_data()
   char       *data= NullS;
   MYSQL_RES  *result;
   MYSQL_BIND bind[3];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_long_data");
 
@@ -2877,6 +2897,7 @@ static void test_long_data_str()
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
   my_bool    is_null[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_long_data_str");
 
@@ -2969,6 +2990,7 @@ static void test_long_data_str1()
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
   MYSQL_FIELD *field;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_long_data_str1");
 
@@ -3124,6 +3146,7 @@ static void test_long_data_bin()
   long       length;
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
 
   myheader("test_long_data_bin");
@@ -3203,6 +3226,7 @@ static void test_simple_delete()
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
   ulong length[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_simple_delete");
 
@@ -3285,6 +3309,7 @@ static void test_update()
   MYSQL_RES  *result;
   MYSQL_BIND bind[2];
   ulong length[2];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_update");
 
@@ -3381,6 +3406,7 @@ static void test_prepare_noparam()
   MYSQL_STMT *stmt;
   int        rc;
   MYSQL_RES  *result;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare_noparam");
 
@@ -4237,6 +4263,7 @@ static void test_prepare_ext()
   short      sData= 10;
   longlong   bData= 20;
   MYSQL_BIND bind[6];
+  char query[MAX_TEST_QUERY_LENGTH];
   myheader("test_prepare_ext");
 
   rc= mysql_query(mysql, "DROP TABLE IF EXISTS test_prepare_ext");
@@ -4624,6 +4651,7 @@ static void test_stmt_close()
   MYSQL_RES   *result;
   unsigned int  count;
   int   rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_stmt_close");
 
@@ -5270,6 +5298,7 @@ static void test_manual_sample()
   ulonglong    affected_rows;
   MYSQL_BIND   bind[3];
   my_bool      is_null;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_manual_sample");
 
@@ -5624,6 +5653,7 @@ static void test_prepare_multi_statements()
 {
   MYSQL *mysql_local;
   MYSQL_STMT *stmt;
+  char query[MAX_TEST_QUERY_LENGTH];
   myheader("test_prepare_multi_statements");
 
   if (!(mysql_local= mysql_init(NULL)))
@@ -5841,6 +5871,7 @@ static void test_store_result2()
   int        nData;
   ulong      length;
   MYSQL_BIND bind[1];
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_store_result2");
 
@@ -7120,6 +7151,7 @@ static void test_set_option()
 static void test_prepare_grant()
 {
   int rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_prepare_grant");
 
@@ -8592,6 +8624,7 @@ static void test_sqlmode()
   MYSQL_BIND bind[2];
   char       c1[5], c2[5];
   int        rc;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_sqlmode");
 
@@ -8735,6 +8768,7 @@ static void test_ts()
   ulong      length;
   int        rc, field_count;
   char       name;
+  char query[MAX_TEST_QUERY_LENGTH];
 
   myheader("test_ts");
 
@@ -15019,6 +15053,65 @@ static void test_bug20152()
   }
 }
 
+/* Bug#15752 "Lost connection to MySQL server when calling a SP from C API" */
+
+static void test_bug15752()
+{
+  MYSQL mysql_local;
+  int rc, i;
+  const int ITERATION_COUNT= 100;
+  char *query= "CALL p1()";
+
+  myheader("test_bug15752");
+
+  rc= mysql_query(mysql, "drop procedure if exists p1");
+  myquery(rc);
+  rc= mysql_query(mysql, "create procedure p1() select 1");
+  myquery(rc);
+
+  mysql_init(&mysql_local);
+  if (! mysql_real_connect(&mysql_local, opt_host, opt_user,
+                           opt_password, current_db, opt_port,
+                           opt_unix_socket,
+                           CLIENT_MULTI_STATEMENTS|CLIENT_MULTI_RESULTS))
+  {
+    printf("Unable connect to MySQL server: %s\n", mysql_error(&mysql_local));
+    DIE_UNLESS(0);
+  }
+  rc= mysql_real_query(&mysql_local, query, strlen(query));
+  myquery(rc);
+  mysql_free_result(mysql_store_result(&mysql_local));
+
+  rc= mysql_real_query(&mysql_local, query, strlen(query));
+  DIE_UNLESS(rc && mysql_errno(&mysql_local) == CR_COMMANDS_OUT_OF_SYNC);
+
+  if (! opt_silent)
+    printf("Got error (as expected): %s\n", mysql_error(&mysql_local));
+
+  /* Check some other commands too */
+
+  DIE_UNLESS(mysql_next_result(&mysql_local) == 0);
+  mysql_free_result(mysql_store_result(&mysql_local));
+  DIE_UNLESS(mysql_next_result(&mysql_local) == -1);
+
+  /* The second problem is not reproducible: add the test case */
+  for (i = 0; i < ITERATION_COUNT; i++)
+  {
+    if (mysql_real_query(&mysql_local, query, strlen(query)))
+    {
+      printf("\ni=%d %s failed: %s\n", i, query, mysql_error(&mysql_local));
+      break;
+    }
+    mysql_free_result(mysql_store_result(&mysql_local));
+    DIE_UNLESS(mysql_next_result(&mysql_local) == 0);
+    mysql_free_result(mysql_store_result(&mysql_local));
+    DIE_UNLESS(mysql_next_result(&mysql_local) == -1);
+
+  }
+  mysql_close(&mysql_local);
+  rc= mysql_query(mysql, "drop procedure p1");
+  myquery(rc);
+}
 
 /*
   Read and parse arguments and MySQL options from my.cnf
@@ -15287,7 +15380,8 @@ static struct my_tests_st my_tests[]= {
   { "test_bug20152", test_bug20152 },
   { "test_bug14169", test_bug14169 },
   { "test_bug17667", test_bug17667 },
-  { "test_bug19671", test_bug19671},
+  { "test_bug19671", test_bug19671 },
+  { "test_bug15752", test_bug15752 },
   { 0, 0 }
 };