Fix for CONC-71: mysql_real_query crashes after server restart

- We now check socket status before net_flush (and return error if the socket is dead)

CMakeLists.txt

@@ -21,12 +21,16 @@ IF(NOT WIN32)
   OPTION(WITH_OPENSSL "enables SSL support" ON)
 ELSE()
   OPTION(WITH_OPENSSL "enables SSL support" OFF)
+  OPTION(WITH_RTC "enables run time checks for debug builds" OFF)
 ENDIF()
 
 OPTION(WITH_SQLITE "Enables Sqlite support" OFF)
 OPTION(WITH_EXTERNAL_ZLIB "Enables use of external zlib" OFF)
 ###############
 
+IF(WITH_RTC)
+  SET(RTC_OPTIONS "/RTC1 /RTCc")
+ENDIF()
 
 IF(MSVC)
   # Speedup system tests
@@ -39,7 +43,7 @@ IF(MSVC)
         IF (NOT COMPILER_FLAGS STREQUAL "")
           STRING(REPLACE "/MD" "/MT" COMPILER_FLAGS ${COMPILER_FLAGS})
           IF (CMAKE_BUILD_TYPE STREQUAL "Debug")
-            SET(COMPILER_FLAGS "${COMPILER_FLAGS} /RTC1 /RTCc")
+            SET(COMPILER_FLAGS "${COMPILER_FLAGS} ${RTC_OPTIONS}")
             STRING(REPLACE "/Zi" "/ZI" COMPILER_FLAGS ${COMPILER_FLAGS})
           ENDIF()
           MESSAGE (STATUS "CMAKE_${COMPILER}_FLAGS_${BUILD_TYPE}= ${COMPILER_FLAGS}") 

libmariadb/CMakeLists.txt

@@ -127,7 +127,6 @@ ELSE()
     ../zlib/compress.c
     ../zlib/crc32.c
     ../zlib/deflate.c
-    ../zlib/example.c
     ../zlib/gzclose.c
     ../zlib/gzlib.c
     ../zlib/gzread.c

libmariadb/net.c

@@ -31,8 +31,8 @@
 #include <signal.h>
 #include <errno.h>
 #include <sys/types.h>
-#ifdef MYSQL_SERVER
-#include <violite.h>
+#ifndef _WIN32
+#include <poll.h>
 #endif
 
 #define MAX_PACKET_LENGTH (256L*256L*256L-1)
@@ -114,8 +114,6 @@ int my_net_init(NET *net, Vio* vio)
 {
   if (!(net->buff=(uchar*) my_malloc(net_buffer_length,MYF(MY_WME | MY_ZEROFILL))))
     return 1;
-//  if (net_buffer_length > max_allowed_packet)
-//    max_allowed_packet=net_buffer_length;
   max_allowed_packet= net->max_packet_size= MAX(net_buffer_length, max_allowed_packet);
   net->buff_end=net->buff+(net->max_packet=net_buffer_length);
   net->vio = vio;
@@ -166,13 +164,10 @@ static my_bool net_realloc(NET *net, size_t length)
     DBUG_RETURN(1);
   }
   pkt_length = (length+IO_SIZE-1) & ~(IO_SIZE-1);
-  if (!(buff=(uchar*) my_realloc((char*) net->buff, pkt_length, MYF(MY_WME))))
+  if (!(buff=(uchar*) my_realloc((char*) net->buff, pkt_length + 1, MYF(MY_WME))))
   {
     DBUG_PRINT("info", ("Out of memory"));
     net->error=1;
-#ifdef MYSQL_SERVER
-    net->last_errno=ER_OUT_OF_RESOURCES;
-#endif
     DBUG_RETURN(1);
   }
   net->buff=net->write_pos=buff;
@@ -180,21 +175,45 @@ static my_bool net_realloc(NET *net, size_t length)
   DBUG_RETURN(0);
 }
 
-#ifdef DEBUG_SOCKET
-static ssize_t net_check_if_data_available(Vio *vio)
+
+/* check if the socket is still alive */
+static my_bool net_check_socket_status(my_socket sock)
 {
-  ssize_t length= 0;
-
-  if (vio->type != VIO_TYPE_SOCKET &&
-      vio->type != VIO_TYPE_TCPIP)
-    return 0;
-
-  if (vio_read_peek(vio, (size_t *)&length))
-    return -1;
-
-  return length;
-}
+#ifndef _WIN32
+  struct pollfd poll_fd;
+#else
+  FD_SET sfds;
+  struct timeval tv= {0,0};
 #endif
+  int res;
+#ifndef _WIN32
+  memset(&poll_fd, 0, sizeof(struct pollfd));
+  poll_fd.events= POLLPRI | POLLIN;
+  poll_fd.fd= sock;
+
+  res= poll(&poll_fd, 1, 0);
+  if (res <= 0) /* timeout or error */
+    return FALSE;
+  if (!(poll_fd.revents & (POLLIN | POLLPRI)))
+    return FALSE;
+  return TRUE;
+#else
+  /* We can't use the WSAPoll function, it's broken :-(
+     (see Windows 8 Bugs 309411 - WSAPoll does not report failed connections)
+     Instead we need to use select function:
+     If TIMEVAL is initialized to {0, 0}, select will return immediately; 
+     this is used to poll the state of the selected sockets.
+  */
+  FD_ZERO(&sfds);
+  FD_SET(sock, &sfds);
+
+  res= select(sock + 1, &sfds, NULL, NULL, &tv);
+  if (res > 0 && FD_ISSET(sock, &sfds))
+    return TRUE;
+  return FALSE;
+#endif
+
+}
 
 	/* Remove unwanted characters from connection */
 
@@ -202,10 +221,19 @@ void net_clear(NET *net)
 {
   DBUG_ENTER("net_clear");
 
-#ifdef DEBUG_SOCKET
-  DBUG_ASSERT(net_check_if_data_available(net->vio) < 2);
-#endif
-
+  /* see conc-71: we need to check the socket status first:
+     if the socket is dead we set net->error, so net_flush
+     will report an error */
+  while (net_check_socket_status(net->vio->sd))
+  {
+    /* vio_read returns size_t. so casting to long is required to check for -1 */
+    if ((long)vio_read(net->vio, (gptr)net->buff, (size_t) net->max_packet) <= 0)
+    {
+      net->error= 2;
+      DBUG_PRINT("info", ("socket disconnected"));
+      DBUG_VOID_RETURN;
+    }
+  }
   net->compress_pkt_nr= net->pkt_nr=0;				/* Ready for new command */
   net->write_pos=net->buff;
   DBUG_VOID_RETURN;
@@ -810,13 +838,14 @@ ulong my_net_read(NET *net)
       net->where_b=buffer_length;
 
       if ((packet_length = my_real_read(net,(size_t *)&complen)) == packet_error)
-        break;
+        return packet_error;
       if (my_uncompress((unsigned char*) net->buff + net->where_b, &packet_length, &complen))
       {
         len= packet_error;
         net->error=2;			/* caller will close socket */
         net->last_errno=ER_NET_UNCOMPRESS_ERROR;
         break;
+        return packet_error;
       }
       buffer_length+= complen;
     }
@@ -827,11 +856,8 @@ ulong my_net_read(NET *net)
     len= current - start - 4;
     if (is_multi_packet)
       len-= 4;
-    if (len != packet_error)
-    {
-      net->save_char= net->read_pos[len];	/* Must be saved */
-      net->read_pos[len]=0;		/* Safeguard for mysql_use_result */
-    }
+    net->save_char= net->read_pos[len];	/* Must be saved */
+    net->read_pos[len]=0;		/* Safeguard for mysql_use_result */
   }
 #endif
   return (ulong)len;

unittest/libmariadb/basic-t.c

@@ -30,6 +30,38 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "my_test.h"
 #include "ma_common.h"
 
+static int test_conc71(MYSQL *my)
+{
+  int rc;
+  MYSQL_RES *res;
+  MYSQL_ROW row;
+  char *query;
+  MYSQL *mysql;
+  
+  /* uncomment if you want to test manually */
+  return SKIP;
+
+  mysql= mysql_init(NULL);
+
+
+  mysql_options(mysql, MYSQL_SET_CHARSET_NAME, "utf8");
+  mysql_options(mysql, MYSQL_OPT_COMPRESS, 0);
+  mysql_options(mysql, MYSQL_INIT_COMMAND, "/*!40101 SET SQL_MODE='' */");
+  mysql_options(mysql, MYSQL_INIT_COMMAND, "/*!40101 set @@session.wait_timeout=28800 */");
+
+  FAIL_IF(!mysql_real_connect(mysql, hostname, username, password, schema,
+                         port, socketname, 0), mysql_error(my));
+
+  diag("kill server");
+  sleep(20);
+
+  rc= mysql_query(mysql, "SELECT 'foo' FROM DUAL");
+  check_mysql_rc(rc, mysql);
+
+  mysql_close(mysql);
+  return OK;
+}
+
 static int test_conc70(MYSQL *my)
 {
   int rc;
@@ -37,7 +69,7 @@ static int test_conc70(MYSQL *my)
   MYSQL_ROW row;
   MYSQL *mysql= mysql_init(NULL);
 
-  mysql_query(my, "SET @a:=@@max_allowed_packet");
+  rc= mysql_query(my, "SET @a:=@@max_allowed_packet");
   check_mysql_rc(rc, my);
 
   mysql_query(my, "SET global max_allowed_packet=1024*1024*22");
@@ -84,7 +116,7 @@ static int test_conc68(MYSQL *my)
   MYSQL_ROW row;
   MYSQL *mysql= mysql_init(NULL);
 
-  mysql_query(my, "SET @a:=@@max_allowed_packet");
+  rc= mysql_query(my, "SET @a:=@@max_allowed_packet");
   check_mysql_rc(rc, my);
 
   mysql_query(my, "SET global max_allowed_packet=1024*1024*22");
@@ -648,6 +680,7 @@ static int test_compressed(MYSQL *my)
 }
 
 struct my_tests_st my_tests[] = {
+  {"test_conc71", test_conc71, TEST_CONNECTION_DEFAULT, 0,  NULL,  NULL},
   {"test_conc70", test_conc70, TEST_CONNECTION_DEFAULT, 0,  NULL,  NULL},
   {"test_conc68", test_conc68, TEST_CONNECTION_DEFAULT, 0,  NULL,  NULL},
   {"test_compressed", test_compressed, TEST_CONNECTION_NONE, 0,  NULL,  NULL},

unittest/libmariadb/logs.c

@@ -65,6 +65,9 @@ static int test_logs(MYSQL *mysql)
   int        rc;
   short      id;
 
+  rc= mysql_query(mysql, "SET session sql_mode=''");
+  check_mysql_rc(rc, mysql);
+
   rc= mysql_query(mysql, "DROP TABLE IF EXISTS test_logs");
   check_mysql_rc(rc, mysql);
 

unittest/libmariadb/my.cnf

@@ -0,0 +1,3 @@
+[conc-66]
+user=conc66
+password='test;#test'

zlib/CMakeLists.txt

@@ -1,13 +1,13 @@
 INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/zlib)
 
-SET(SOURCE_FILES adler32.c compress.c crc32.c deflate.c example.c gzclose.c gzlib.c gzread.c gzwrite.c infback.c inffast.c inflate.c inftrees.c minigzip.c trees.c uncompr.c zutil.c)
+SET(SOURCE_FILES adler32.c compress.c crc32.c deflate.c gzclose.c gzlib.c gzread.c gzwrite.c infback.c inffast.c inflate.c inftrees.c minigzip.c trees.c uncompr.c zutil.c)
 
 ADD_LIBRARY(zlib ${SOURCE_FILES})
 SET_TARGET_PROPERTIES(zlib PROPERTIES  COMPILE_FLAGS
    "${CMAKE_SHARED_LIBRARY_C_FLAGS}")
 
-  INSTALL(TARGETS
-           zlib
-          RUNTIME DESTINATION "lib"
-          LIBRARY DESTINATION "lib"
-          ARCHIVE DESTINATION "lib")
+INSTALL(TARGETS
+        zlib
+        RUNTIME DESTINATION "lib"
+        LIBRARY DESTINATION "lib"
+        ARCHIVE DESTINATION "lib")