MDEV-3842, MDEV-3923 :

Miscellaneous workarounds for  drop-in compatibility problems with Linux distributions, arounf versioning of the 
MySQL 5.5 client shared library. There seems to be 3 different ways major distributions handle versioning

1. Fedora  (also Mageia, and likely  other Redhat descendants) way 
   old, 5.1 API functions are given version libmysqlclient_16
   new API functions  (client plugins, mysql_stmt_next ) are given version libmysqlclient_18
   some extra functions beyond API are exported.
   some functions are renamed.

2.Debian Wheezy way 
  all functions are given libmysqlclient_18 version

3. Ubuntu  way (or MySQL/MariaDB download packages)
  no versioning

UIp to this fix, MariaDB distributions did not have any versioning in the libraries, this rendered client library incompatible to distributions 
thus exchanging  distribution's libmysqlclient.so.18.0.0  with MariaDB's did not work nicely (anywhere but on Ubuntu)


THE FIX  
is to build libraries the same way as distributions do it 
- when building RPMs, use  same version script as Fedora does, Make sure to export extra-symbols, the same as Fedora exports.
- when building DEBs, use the same version script as Debian Wheezy
- do not use version scripts otherwise


Also, makes sure that extensions of  MySQL APIs (asynchronous client functionality) is exported by  the shared libraries.

libmysql/CMakeLists.txt

@@ -23,7 +23,7 @@ INCLUDE_DIRECTORIES(
   ${ZLIB_INCLUDE_DIR})
 ADD_DEFINITIONS(${SSL_DEFINES})
 
-SET(CLIENT_API_FUNCTIONS
+SET(CLIENT_API_FUNCTIONS_5_1
 get_tty_password
 handle_options
 load_defaults
@@ -58,6 +58,7 @@ mysql_field_count
 mysql_field_seek
 mysql_field_tell
 mysql_free_result
+mysql_get_parameters
 mysql_get_client_info
 mysql_get_host_info
 mysql_get_proto_info
@@ -129,12 +130,164 @@ mysql_server_init
 mysql_server_end
 mysql_set_character_set
 mysql_get_character_set_info
-mysql_stmt_next_result
+)
 
-CACHE INTERNAL "Functions exported by client API"
+SET(CLIENT_API_FUNCTIONS_5_5
+mysql_stmt_next_result
+# Client plugins
+mysql_client_find_plugin
+mysql_client_register_plugin
+mysql_load_plugin
+mysql_load_plugin_v
+mysql_plugin_options
+# Async API
+mysql_autocommit_cont
+mysql_autocommit_start
+mysql_change_user_cont
+mysql_change_user_start
+mysql_close_cont
+mysql_close_slow_part_cont
+mysql_close_slow_part_start
+mysql_close_start
+mysql_commit_cont
+mysql_commit_start
+mysql_fetch_row_cont
+mysql_fetch_row_start
+mysql_free_result_cont
+mysql_free_result_start
+mysql_kill_cont
+mysql_kill_start
+mysql_list_dbs_cont
+mysql_list_dbs_start
+mysql_list_fields_cont
+mysql_list_fields_start
+mysql_list_processes_cont
+mysql_list_processes_start
+mysql_list_tables_cont
+mysql_list_tables_start
+mysql_next_result_cont
+mysql_next_result_start
+mysql_ping_cont
+mysql_ping_start
+mysql_query_cont
+mysql_query_start
+mysql_read_query_result_cont
+mysql_read_query_result_start
+mysql_real_connect_cont
+mysql_real_connect_start
+mysql_real_query_cont
+mysql_real_query_start
+mysql_refresh_cont
+mysql_refresh_start
+mysql_rollback_cont
+mysql_rollback_start
+mysql_select_db_cont
+mysql_select_db_start
+mysql_send_query_cont
+mysql_send_query_start
+mysql_set_character_set_cont
+mysql_set_character_set_start
+mysql_set_server_option_cont
+mysql_set_server_option_start
+mysql_shutdown_cont
+mysql_shutdown_start
+mysql_stat_cont
+mysql_stat_start
+mysql_stmt_close_cont
+mysql_stmt_close_start
+mysql_stmt_execute_cont
+mysql_stmt_execute_start
+mysql_stmt_fetch_cont
+mysql_stmt_fetch_start
+mysql_stmt_free_result_cont
+mysql_stmt_free_result_start
+mysql_stmt_next_result_cont
+mysql_stmt_next_result_start
+mysql_stmt_prepare_cont
+mysql_stmt_prepare_start
+mysql_stmt_reset_cont
+mysql_stmt_reset_start
+mysql_stmt_send_long_data_cont
+mysql_stmt_send_long_data_start
+mysql_stmt_store_result_cont
+mysql_stmt_store_result_start
+mysql_store_result_cont
+mysql_store_result_start
+)
 
+SET(CLIENT_API_FUNCTIONS
+  ${CLIENT_API_FUNCTIONS_5_1}
+  ${CLIENT_API_FUNCTIONS_5_5}
+  CACHE INTERNAL
+  "Client functions"
 )
 
+IF(CMAKE_SYSTEM_NAME MATCHES "Linux") 
+  # When building RPM, or DEB package on Debian, use ELF symbol versioning
+  # for compatibility with distribution packages, so client shared library can 
+  # painlessly replace the one supplied by the distribution.
+  
+  # Also list of exported symbols in distributions may differ from what is considered
+  # official API. Define CLIENT_API_EXTRA for the set of symbols, that required to
+  # be exported on different platforms.
+  
+  IF(RPM)
+    # Fedora & Co declared following functions as part of API 
+    # These functions are alias of another function (given mysql_ prefix=. The 
+    # renaming is handled in rpm_support.cc below
+    SET(CLIENT_API_EXTRA
+      mysql_default_charset_info
+      mysql_get_charset
+      mysql_get_charset_by_csname
+      mysql_net_realloc
+      mysql_client_errors
+    )
+    # Add special script to fix symbols renames by Fedora
+    SET(CLIENT_SOURCES_EXTRA ${CLIENT_SOURCES} rpm_support.cc)
+    SET(VERSION_SCRIPT_TEMPLATE 
+    ${CMAKE_CURRENT_SOURCE_DIR}/libmysql_rpm_version.in)	  
+  ELSEIF(DEB)
+    # libmyodbc on Ubuntu is using functions below
+    # If we don't export them, linker would just remove 
+    # them (they are not used inside libmysqlclient)
+    SET(CLIENT_API_EXTRA
+      strfill
+      init_dynamic_string
+    )
+    # MySQL supplied with Ubuntu does not have versioning, bug Debian does.
+    IF(DEB MATCHES "debian") 
+      SET(VERSION_SCRIPT_TEMPLATE ${CMAKE_CURRENT_SOURCE_DIR}/libmysql.ver.in)
+    ENDIF()
+  ENDIF()
+
+  IF(VERSION_SCRIPT_TEMPLATE)
+    # Generate version script.  
+    # Create semicolon separated lists of functions to export from 
+    # Since RPM packages use separate versioning for 5.1 API
+    # and 5.5 API (libmysqlclient_16 vs libmysqlclient_18), 
+    # we need 2 lists.
+    SET (CLIENT_API_5_1_LIST)
+    FOREACH (f ${CLIENT_API_FUNCTIONS_5_1})
+      SET(CLIENT_API_5_1_LIST "${CLIENT_API_5_1_LIST}\n${f};")
+    ENDFOREACH()
+	
+    SET (CLIENT_API_5_5_LIST)
+    FOREACH (f ${CLIENT_API_FUNCTIONS_5_5})
+      SET(CLIENT_API_5_5_LIST "${CLIENT_API_5_5_LIST}\n${f};")
+    ENDFOREACH()
+
+    CONFIGURE_FILE(
+      ${VERSION_SCRIPT_TEMPLATE}
+      ${CMAKE_CURRENT_BINARY_DIR}/libmysql.version
+      @ONLY@
+    )
+    SET(VERSION_SCRIPT_LINK_FLAGS 
+      "-Wl,--version-script=${CMAKE_CURRENT_BINARY_DIR}/libmysql.version")
+  ENDIF()
+  
+ENDIF()
+
+
 SET(CLIENT_SOURCES
   get_password.c 
   libmysql.c
@@ -146,6 +299,7 @@ SET(CLIENT_SOURCES
   ../sql/net_serv.cc
   ../sql-common/pack.c 
   ../sql/password.c
+  ${CLIENT_SOURCES_EXTRA}
 )
 ADD_CONVENIENCE_LIBRARY(clientlib ${CLIENT_SOURCES})
 DTRACE_INSTRUMENT(clientlib)
@@ -193,13 +347,13 @@ IF(NOT DISABLE_SHARED)
       OUTPUT_NAME mysqlclient 
       VERSION "${OS_SHARED_LIB_VERSION}" 
       SOVERSION "${SHARED_LIB_MAJOR_VERSION}")
-    IF(LINK_FLAG_NO_UNDEFINED)
+    IF(LINK_FLAG_NO_UNDEFINED OR VERSION_SCRIPT_LINK_FLAGS)
       GET_TARGET_PROPERTY(libmysql_link_flags libmysql LINK_FLAGS)
       IF(NOT libmysql_link_flag)
         SET(libmysql_link_flags)
       ENDIF()
       SET_TARGET_PROPERTIES(libmysql PROPERTIES LINK_FLAGS 
-        "${libmysql_link_flags} ${LINK_FLAG_NO_UNDEFINED}")
+        "${libmysql_link_flags} ${LINK_FLAG_NO_UNDEFINED} ${VERSION_SCRIPT_LINK_FLAGS}")
     ENDIF() 
     # clean direct output needs to be set several targets have the same name
     #(mysqlclient in this case)

libmysql/libmysql_rpm_version.in

+# This version script is heavily inspired  by Fedora's and Mageia's version scripts for
+# MySQL client shared library. It is used in MariaDB for building RPMs.
+
+libmysqlclient_16 {
+  global:
+@CLIENT_API_5_1_LIST@
+
+# some stuff from Mageia, I have no idea why it is there
+# But too afraid to throw anything away
+	_fini;
+	_init;
+	my_init;
+	my_progname;
+	myodbc_remove_escape;
+
+# These are documented in Paul DuBois' MySQL book, so we treat them as part
+# of the de-facto API.
+	free_defaults;
+	handle_options;
+	load_defaults;
+	my_print_help;
+# pure-ftpd requires this
+	my_make_scrambled_password;
+# hydra requires this
+	scramble;
+# DBD::mysql requires this
+	is_prefix;
+  local:
+	*;
+};
+
+libmysqlclient_18 {
+  global:
+	@CLIENT_API_5_5_LIST@
+#
+# Ideally the following symbols wouldn't be exported, but various applications
+# require them.  We limit the namespace damage by prefixing mysql_
+# (see mysql-dubious-exports.patch), which means the symbols are not present
+# in libmysqlclient_16.
+#
+# mysql-connector-odbc requires these
+	mysql_default_charset_info;
+	mysql_get_charset;
+	mysql_get_charset_by_csname;
+	mysql_net_realloc;
+# PHP's mysqli.so requires this (via the ER() macro)
+	mysql_client_errors;
+};

libmysql/rpm_support.cc

+/*
+  Provide aliases for several symbols, to support drop-in replacement for
+  MariaDB on Fedora and several derives distributions.
+
+  These distributions redefine several symbols (in a way that is no compatible
+  with either MySQL or MariaDB) and export it from the client library ( as seen
+  e.g from this patch)
+http://lists.fedoraproject.org/pipermail/scm-commits/2010-December/537257.html
+
+  MariaDB handles compatibility distribution by providing the same symbols from 
+  the client library if it is built with -DRPM
+
+*/
+#include <errmsg.h>
+#include <my_sys.h>
+#include <mysql.h>
+extern "C" {
+
+CHARSET_INFO *mysql_default_charset_info = default_charset_info;
+
+CHARSET_INFO *mysql_get_charset(uint cs_number, myf flags)
+{
+  return get_charset(cs_number, flags);
+}
+
+CHARSET_INFO *mysql_get_charset_by_csname(const char *cs_name,
+                                           uint cs_flags, myf my_flags)
+{
+   return get_charset_by_csname(cs_name, cs_flags, my_flags);
+}
+
+
+my_bool mysql_net_realloc(NET *net, size_t length)
+{
+   return net_realloc(net,length);
+}
+
+const char **mysql_client_errors = client_errors;
+
+} /*extern "C" */
+

libmysqld/CMakeLists.txt

@@ -146,8 +146,19 @@ IF(UNIX)
   ${CMAKE_STATIC_LIBRARY_PREFIX}mysqld-debug)
 ENDIF()
 
+# List of exported functions in embedded (client api except client plugin or 
+# async (*_start/*_cont functions)
+
+SET(EMBEDDED_API)
+FOREACH(f ${CLIENT_API})
+  IF(NOT(f MATCHES "plugin|_start$|_cont$"))
+    SET(EMBEDDED_API ${EMBEDDED_API) ${f})
+  ENDIF()	
+ENDFOREACH()
+MESSAGE("embedded api=${EMBEDDED_API}")
+
 IF(NOT DISABLE_SHARED)
-  MERGE_LIBRARIES(libmysqld SHARED mysqlserver EXPORTS ${CLIENT_API_FUNCTIONS}
+  MERGE_LIBRARIES(libmysqld SHARED mysqlserver EXPORTS ${EMBEDDED_API}
     COMPONENT Server) 
   IF(UNIX)
     # Name the shared library, handle versioning (provides same api as client