Fix for BUG#51215 "log-error partially works with version 5.5": WL 4738 (reengineering of server variables)

had broken the 5.1 behaviour of --log-error: --log-error without argument sent to stderr instead of writing
to a file with an autogenerated name.

mysql-test/suite/sys_vars/t/log_error_func.test:
  test that error log is created and shown in SHOW VARIABLES.
  Interestingly the error log's path is apparently relative if --log-error=argument is used, but
  may be absolute or relative if --log-error(no argument) is used (because then the path is derived from
  that of pidfile_name, which can be absolute or relative, depending on if autogenerated or not).
mysql-test/suite/sys_vars/t/log_error_func2.test:
  test that error log is created and shown in SHOW VARIABLES
mysql-test/suite/sys_vars/t/log_error_func3.test:
  test that error log is empty in SHOW VARIABLES
sql/mysql_priv.h:
  id for option --log-error
sql/mysqld.cc:
  No --log-error means "write errors to stderr", whereas --log-error
  without argument means "write errors to a file". So we cannot use the default logic
  of class sys_var_charptr, which treats "option not used" the same as "option used
  without argument" and uses the same default for both. We need to catch "option used",
  in mysqld_get_one_option(), and then "without argument". Setting to "" makes sure
  that init_server_components() will create the log, with an autogenerated name.
sql/sys_vars.cc:
  need to give the option a numeric id so that we can catch it in mysqld_get_one_option()

8 files changed, 70 insertions, 0 deletions

diff --git a/mysql-test/suite/sys_vars/r/log_error_func.result b/mysql-test/suite/sys_vars/r/log_error_func.result
new file mode 100644
index 00000000000..c787c5ceb4f
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/log_error_func.result
@@ -0,0 +1,6 @@
+select (@err_log:=variable_value)*0 from information_schema.global_variables where variable_name="log_error";
+(@err_log:=variable_value)*0
+0
+select instr(@err_log, "some_random_name5435413.err")>0;
+instr(@err_log, "some_random_name5435413.err")>0
+1
diff --git a/mysql-test/suite/sys_vars/r/log_error_func2.result b/mysql-test/suite/sys_vars/r/log_error_func2.result
new file mode 100644
index 00000000000..82720035886
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/log_error_func2.result
@@ -0,0 +1,6 @@
+select (@err_log:=variable_value)*0 from information_schema.global_variables where variable_name="log_error";
+(@err_log:=variable_value)*0
+0
+select instr(@err_log, ".err")>0;
+instr(@err_log, ".err")>0
+1
diff --git a/mysql-test/suite/sys_vars/r/log_error_func3.result b/mysql-test/suite/sys_vars/r/log_error_func3.result
new file mode 100644
index 00000000000..ff1908defd1
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/log_error_func3.result
@@ -0,0 +1,3 @@
+select variable_value from information_schema.global_variables where variable_name="log_error";
+variable_value
+
diff --git a/mysql-test/suite/sys_vars/t/log_error_func.cnf b/mysql-test/suite/sys_vars/t/log_error_func.cnf
new file mode 100644
index 00000000000..7a030b5518d
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/log_error_func.cnf
@@ -0,0 +1,5 @@
+# Use default setting for mysqld processes
+!include include/default_mysqld.cnf
+
+[mysqld.1]
+log-error=some_random_name5435413
diff --git a/mysql-test/suite/sys_vars/t/log_error_func.test b/mysql-test/suite/sys_vars/t/log_error_func.test
new file mode 100644
index 00000000000..1cd45a54ff7
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/log_error_func.test
@@ -0,0 +1,20 @@
+# Test for BUG#51215 "log-error partially works with version 5.5"
+# when --log-error is used without argument
+
+# check displayed value. We can check only the base name, the rest
+# depends on paths, symbolic links, --vardir, etc...
+select (@err_log:=variable_value)*0 from information_schema.global_variables where variable_name="log_error";
+select instr(@err_log, "some_random_name5435413.err")>0;
+
+# Check file's existence. The displayed value may be relative or not.
+let $err_log=`select @err_log`;
+let $err_log_relative=`select instr(@err_log, ".")=1`;
+if ($err_log_relative)
+{
+  let $MYSQLD_DATADIR= `SELECT @@datadir`;
+  file_exists $MYSQLD_DATADIR/$err_log;
+}
+if (!$err_log_relative)
+{
+  file_exists $err_log;
+}
diff --git a/mysql-test/suite/sys_vars/t/log_error_func2.cnf b/mysql-test/suite/sys_vars/t/log_error_func2.cnf
new file mode 100644
index 00000000000..ff7e8f7a101
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/log_error_func2.cnf
@@ -0,0 +1,5 @@
+# Use default setting for mysqld processes
+!include include/default_mysqld.cnf
+
+[mysqld.1]
+log-error
diff --git a/mysql-test/suite/sys_vars/t/log_error_func2.test b/mysql-test/suite/sys_vars/t/log_error_func2.test
new file mode 100644
index 00000000000..e9f91e9c032
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/log_error_func2.test
@@ -0,0 +1,20 @@
+# Test for BUG#51215 "log-error partially works with version 5.5"
+# when --log-error is used without argument
+
+# check displayed value. We can check only the suffix, because
+# the rest depends on paths, symbolic links, --vardir, etc...
+select (@err_log:=variable_value)*0 from information_schema.global_variables where variable_name="log_error";
+select instr(@err_log, ".err")>0;
+
+# Check file's existence. The displayed value may be relative or not.
+let $err_log=`select @err_log`;
+let $err_log_relative=`select instr(@err_log, ".")=1`;
+if ($err_log_relative)
+{
+  let $MYSQLD_DATADIR= `SELECT @@datadir`;
+  file_exists $MYSQLD_DATADIR/$err_log;
+}
+if (!$err_log_relative)
+{
+  file_exists $err_log;
+}
diff --git a/mysql-test/suite/sys_vars/t/log_error_func3.test b/mysql-test/suite/sys_vars/t/log_error_func3.test
new file mode 100644
index 00000000000..c6b076f39fb
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/log_error_func3.test
@@ -0,0 +1,5 @@
+# Test for BUG#51215 "log-error partially works with version 5.5"
+# when --log-error is not used
+
+# check displayed value. Should be empty.
+select variable_value from information_schema.global_variables where variable_name="log_error";