Ensure that one can't from the command line set a variable too small. (Bug #2710)

Allow one to force lower_case_table_names to 0, even if the file system is case insensitive. This fixes some issues on Mac OS X (Bug #2994)
Added variables "lower_case_file_system", "version_compile_os" and "license"

mysql-test/r/lowercase0.require

+Variable_name	Value
+lower_case_file_system	ON
+lower_case_table_names	0

mysql-test/r/lowercase_table3.result

+DROP TABLE IF EXISTS t1,T1;
+CREATE TABLE t1 (a int);
+SELECT * from T1;
+a
+drop table t1;
+flush tables;
+CREATE TABLE t1 (a int) type=INNODB;
+SELECT * from T1;
+Table 'test.T1' doesn't exist
+drop table t1;

mysql-test/r/true.require

+TRUE
+1

mysql-test/t/lowercase_table3.test

+#
+# Test of force of lower-case-table-names=0
+# (User has case insensitive file system and want's to preserve case of
+# table names)
+#
+
+--source include/have_innodb.inc
+--require r/lowercase0.require
+disable_query_log;
+show variables like "lower_case_%";
+--require r/true.require
+select @@version_compile_os NOT IN ("NT","WIN2000","Win95/Win98","XP") as "TRUE";
+enable_query_log;
+
+--disable_warnings
+DROP TABLE IF EXISTS t1,T1;
+--enable_warnings
+
+#
+# This is actually an error, but ok as the user has forced this
+# by using --lower-case-table-names=0
+
+CREATE TABLE t1 (a int);
+SELECT * from T1;
+drop table t1;
+flush tables;
+
+#
+# InnoDB should in this case be case sensitive
+# Note that this is not true on windows as no this OS, InnoDB is always
+# storing things in lower case.
+#
+
+CREATE TABLE t1 (a int) type=INNODB;
+--error 1146
+SELECT * from T1;
+drop table t1;

mysys/my_getopt.c

@@ -576,18 +576,15 @@ static longlong eval_num_suffix (char *argument, int *error, char *option_name)
 static longlong getopt_ll(char *arg, const struct my_option *optp, int *err)
 {
   longlong num;
+  ulonglong block_size= (optp->block_size ? (ulonglong) optp->block_size : 1L);
   
   num= eval_num_suffix(arg, err, (char*) optp->name);
-  if (num < (longlong) optp->min_value)
-    num= (longlong) optp->min_value;
-  else if (num > 0 && (ulonglong) num > (ulonglong) (ulong) optp->max_value
-	   && optp->max_value) /* if max value is not set -> no upper limit */
+  if (num > 0 && (ulonglong) num > (ulonglong) (ulong) optp->max_value &&
+      optp->max_value) /* if max value is not set -> no upper limit */
     num= (longlong) (ulong) optp->max_value;
-  num= ((num - (longlong) optp->sub_size) / (optp->block_size ?
-					     (ulonglong) optp->block_size :
-					     1L));
-  return (longlong) (num * (optp->block_size ? (ulonglong) optp->block_size :
-			    1L));
+  num= ((num - (longlong) optp->sub_size) / block_size);
+  num= (longlong) (num * block_size);
+  return max(num, optp->min_value);
 }
 
 /*

sql/mysql_priv.h

@@ -710,7 +710,7 @@ extern uint volatile thread_count, thread_running, global_read_lock;
 extern my_bool opt_sql_bin_update, opt_safe_user_create, opt_no_mix_types;
 extern my_bool opt_safe_show_db, opt_local_infile;
 extern my_bool opt_slave_compressed_protocol, use_temp_pool;
-extern my_bool opt_readonly;
+extern my_bool opt_readonly, lower_case_file_system;
 extern my_bool opt_enable_named_pipe, opt_sync_frm;
 
 extern MYSQL_LOG mysql_log,mysql_update_log,mysql_slow_log,mysql_bin_log;

sql/mysqld.cc

@@ -287,8 +287,10 @@ char log_error_file[FN_REFLEN];
 bool opt_log, opt_update_log, opt_bin_log, opt_slow_log;
 bool opt_error_log= IF_WIN(1,0);
 bool opt_disable_networking=0, opt_skip_show_db=0;
+bool lower_case_table_names_used= 0;
 my_bool opt_enable_named_pipe= 0, opt_debugging= 0;
 my_bool opt_local_infile, opt_external_locking, opt_slave_compressed_protocol;
+my_bool lower_case_file_system= 0;
 uint delay_key_write_options= (uint) DELAY_KEY_WRITE_ON;
 uint lower_case_table_names;
 
@@ -2106,10 +2108,23 @@ int main(int argc, char **argv)
     get corrupted if accesses with names of different case.
   */
   if (!lower_case_table_names &&
-      test_if_case_insensitive(mysql_real_data_home) == 1)
+      (lower_case_file_system=
+       (test_if_case_insensitive(mysql_real_data_home) == 1)))
   {
-    sql_print_error("Warning: Setting lower_case_table_names=2 because file system for %s is case insensitive", mysql_real_data_home);
-    lower_case_table_names= 2;
+    if (lower_case_table_names_used)
+    {
+      sql_print_error("\
+Warning: You have forced lower_case_table_names to 0 through a command line \
+option, even if your file system '%s' is case insensitive.  This means that \
+you can corrupt an MyISAM table by accessing it with different cases.  You \
+should consider changing lower_case_table_names to 1 or 2",
+		      mysql_real_data_home);
+    }
+    else
+    {
+      sql_print_error("Warning: Setting lower_case_table_names=2 because file system for %s is case insensitive", mysql_real_data_home);
+      lower_case_table_names= 2;
+    }
   }
 
 #ifdef HAVE_OPENSSL
@@ -4845,6 +4860,7 @@ get_one_option(int optid, const struct my_option *opt __attribute__((unused)),
     break;
   case OPT_LOWER_CASE_TABLE_NAMES:
     lower_case_table_names= argument ? atoi(argument) : 1;
+    lower_case_table_names_used= 1;
     break;
   }
   return 0;

sql/set_var.cc

@@ -329,9 +329,16 @@ static sys_var_rand_seed2	sys_rand_seed2("rand_seed2");
 static sys_var_thd_ulong        sys_default_week_format("default_week_format",
 							&SV::default_week_format);
 
+static const char license[]= "GPL";
+
+/* Read only variables */
+
+sys_var_const_str		sys_os("version_compile_os", SYSTEM_TYPE);
+sys_var_const_str		sys_license("license", license);
+
 /* Global read-only variable describing server license */
 
-static const char license[]= "GPL";
+
 
 
 /*
@@ -368,6 +375,7 @@ sys_var *sys_variables[]=
   &sys_join_buffer_size,
   &sys_key_buffer_size,
   &sys_last_insert_id,
+  &sys_license,
   &sys_local_infile,
   &sys_log_binlog,
   &sys_log_off,
@@ -434,6 +442,7 @@ sys_var *sys_variables[]=
   &sys_trans_alloc_block_size,
   &sys_trans_prealloc_size,
   &sys_tx_isolation,
+  &sys_os,
 #ifdef HAVE_INNOBASE_DB
   &sys_innodb_max_dirty_pages_pct,
 #endif    
@@ -512,8 +521,8 @@ struct show_var_st init_vars[]= {
   {sys_join_buffer_size.name,   (char*) &sys_join_buffer_size,	    SHOW_SYS},
   {sys_key_buffer_size.name,	(char*) &sys_key_buffer_size,	    SHOW_SYS},
   {"language",                language,                             SHOW_CHAR},
-  {"large_files_support",     (char*) &opt_large_files,             SHOW_BOOL},	
-  {"license",                 (char*) license,                      SHOW_CHAR},	
+  {"large_files_support",     (char*) &opt_large_files,             SHOW_BOOL},
+  {sys_license.name,	      (char*) &sys_license,                 SHOW_SYS},
   {sys_local_infile.name,     (char*) &sys_local_infile,	    SHOW_SYS},
 #ifdef HAVE_MLOCKALL
   {"locked_in_memory",	      (char*) &locked_in_memory,	    SHOW_BOOL},
@@ -526,6 +535,7 @@ struct show_var_st init_vars[]= {
   {sys_log_warnings.name,     (char*) &sys_log_warnings,	    SHOW_SYS},
   {sys_long_query_time.name,  (char*) &sys_long_query_time, 	    SHOW_SYS},
   {sys_low_priority_updates.name, (char*) &sys_low_priority_updates, SHOW_SYS},
+  {"lower_case_file_system",  (char*) &lower_case_file_system,      SHOW_BOOL},
   {"lower_case_table_names",  (char*) &lower_case_table_names,      SHOW_INT},
   {sys_max_allowed_packet.name,(char*) &sys_max_allowed_packet,	    SHOW_SYS},
   {sys_max_binlog_cache_size.name,(char*) &sys_max_binlog_cache_size, SHOW_SYS},
@@ -606,6 +616,7 @@ struct show_var_st init_vars[]= {
   {sys_trans_prealloc_size.name, (char*) &sys_trans_prealloc_size,  SHOW_SYS},
   {"version",                 server_version,                       SHOW_CHAR},
   {"version_comment",         (char*) MYSQL_COMPILATION_COMMENT,    SHOW_CHAR},
+  {sys_os.name,		      (char*) &sys_os,			    SHOW_SYS},
   {sys_net_wait_timeout.name, (char*) &sys_net_wait_timeout,	    SHOW_SYS},
   {NullS, NullS, SHOW_LONG}
 };

sql/set_var.h

@@ -156,6 +156,31 @@ class sys_var_str :public sys_var
 };
 
 
+class sys_var_const_str :public sys_var
+{
+public:
+  char *value;					// Pointer to const value
+  sys_var_const_str(const char *name_arg, const char *value_arg)
+    :sys_var(name_arg), value((char*) value_arg)
+  {}
+  bool check(THD *thd, set_var *var)
+  {
+    return 1;
+  }
+  bool update(THD *thd, set_var *var)
+  {
+    return 1;
+  }
+  SHOW_TYPE type() { return SHOW_CHAR; }
+  byte *value_ptr(THD *thd, enum_var_type type) { return (byte*) value; }
+  bool check_update_type(Item_result type)
+  {
+    return 1;
+  }
+  bool check_default(enum_var_type type) { return 1; }
+};
+
+
 class sys_var_enum :public sys_var
 {
   uint	*value; 

sql/sql_select.cc

@@ -1374,7 +1374,7 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
 	   sizeof(POSITION)*join->const_tables);
     join->best_read=1.0;
   }
-  DBUG_RETURN(get_best_combination(join));
+  DBUG_RETURN(join->thd->killed || get_best_combination(join));
 }
 
 
@@ -1904,6 +1904,8 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
   ha_rows rec;
   double tmp;
   THD *thd= join->thd;
+  if (thd->killed)				// Abort
+    return;
 
   if (!rest_tables)
   {