MDEV-16944 Fix file sharing issues on Windows in mysqltest

On Windows systems, occurrences of ERROR_SHARING_VIOLATION due to
conflicting share modes between processes accessing the same file can
result in CreateFile failures.

mysys' my_open() already incorporates a workaround by implementing
wait/retry logic on Windows.

But this does not help if files are opened using shell redirection like
mysqltest traditionally did it, i.e via

--echo exec "some text" > output_file

In such cases, it is cmd.exe, that opens the output_file, and it
won't do any sharing-violation retries.

This commit addresses the issue by introducing a new built-in command,
'write_line', in mysqltest. This new command serves as a brief alternative
to 'write_file', with a single line output, that also resolves variables
like "exec" would.

Internally, this command will use my_open(), and therefore retry-on-error
logic.

Hopefully this will eliminate the very sporadic "can't open file because
it is used by another process" error on CI.

client/mysqltest.cc

@@ -398,7 +398,7 @@ enum enum_commands {
   Q_IF,
   Q_DISABLE_PARSING, Q_ENABLE_PARSING,
   Q_REPLACE_REGEX, Q_REMOVE_FILE, Q_FILE_EXIST,
-  Q_WRITE_FILE, Q_COPY_FILE, Q_PERL, Q_DIE, Q_EXIT, Q_SKIP,
+  Q_WRITE_FILE, Q_WRITE_LINE, Q_COPY_FILE, Q_PERL, Q_DIE, Q_EXIT, Q_SKIP,
   Q_CHMOD_FILE, Q_APPEND_FILE, Q_CAT_FILE, Q_DIFF_FILES,
   Q_SEND_QUIT, Q_CHANGE_USER, Q_MKDIR, Q_RMDIR,
   Q_LIST_FILES, Q_LIST_FILES_WRITE_FILE, Q_LIST_FILES_APPEND_FILE,
@@ -501,6 +501,7 @@ const char *command_names[]=
   "remove_file",
   "file_exists",
   "write_file",
+  "write_line",
   "copy_file",
   "perl",
   "die",
@@ -4302,6 +4303,49 @@ void do_write_file(struct st_command *command)
   do_write_file_command(command, FALSE);
 }
 
+/**
+  Write a line to the start of the file.
+  Truncates existing file, creates new one if it doesn't exist.
+
+  Usage
+  write_line <line> <filename>;
+
+  Example
+  --write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+
+  @note Both the file and the line parameters are evaluated
+  (can be variables).
+
+  @note This is a better alternative to
+  exec echo > file, as it doesn't depend on shell,
+  and can better handle sporadic file access errors caused
+  by antivirus or backup software on Windows.
+*/
+void do_write_line(struct st_command *command)
+{
+  DYNAMIC_STRING ds_line;
+  DYNAMIC_STRING ds_filename;
+
+  struct command_arg write_line_args[] = {
+    { "line", ARG_STRING, FALSE, &ds_line, "line to add" },
+    { "filename", ARG_STRING, TRUE, &ds_filename, "File to write to" },
+  };
+  DBUG_ENTER("do_write_line");
+
+  check_command_args(command,
+                     command->first_argument,
+                     write_line_args,
+                     sizeof(write_line_args)/sizeof(struct command_arg),
+                     ' ');
+
+  if (bad_path(ds_filename.str))
+    DBUG_VOID_RETURN;
+  dynstr_append_mem(&ds_line, "\n", 1);
+  str_to_file2(ds_filename.str, ds_line.str, ds_line.length, FALSE);
+  dynstr_free(&ds_filename);
+  dynstr_free(&ds_line);
+  DBUG_VOID_RETURN;
+}
 
 /*
   SYNOPSIS
@@ -7423,7 +7467,7 @@ void str_to_file2(const char *fname, char *str, size_t size, my_bool append)
     die("Could not open '%s' for writing, errno: %d", buff, errno);
   if (append && my_seek(fd, 0, SEEK_END, MYF(0)) == MY_FILEPOS_ERROR)
     die("Could not find end of file '%s', errno: %d", buff, errno);
-  if (my_write(fd, (uchar*)str, size, MYF(MY_WME|MY_FNABP)))
+  if (size > 0 && my_write(fd, (uchar*)str, size, MYF(MY_WME|MY_FNABP)))
     die("write failed, errno: %d", errno);
   my_close(fd, MYF(0));
 }
@@ -10160,6 +10204,7 @@ int main(int argc, char **argv)
         break;
       case Q_FILE_EXIST: do_file_exist(command); break;
       case Q_WRITE_FILE: do_write_file(command); break;
+      case Q_WRITE_LINE: do_write_line(command); break;
       case Q_APPEND_FILE: do_append_file(command); break;
       case Q_DIFF_FILES: do_diff_files(command); break;
       case Q_SEND_QUIT: do_send_quit(command); break;

mysql-test/include/crash_mysqld.inc

@@ -4,7 +4,7 @@
 --source include/not_embedded.inc
 
 # Write file to make mysql-test-run.pl expect crash and restart
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 # Setup the mysqld to crash at shutdown
 SET debug_dbug="d,crash_shutdown";

mysql-test/include/expect_crash.inc

@@ -2,4 +2,4 @@
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/$_expect_file_name.expect
 
 # There should be a debug crash after using this .inc file
---exec echo "wait" > $_expect_file_name
+--write_line wait $_expect_file_name

mysql-test/include/kill_and_restart_mysqld.inc

@@ -7,7 +7,7 @@ if (!$restart_parameters)
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/mysqld.$_server_id.expect
 
 --echo # Kill and $restart_parameters
---exec echo "$restart_parameters" > $_expect_file_name
+--write_line "$restart_parameters" $_expect_file_name
 --shutdown_server 0
 --source include/wait_until_disconnected.inc
 --enable_reconnect

mysql-test/include/kill_galera.inc

@@ -3,7 +3,7 @@
 # Write file to make mysql-test-run.pl expect the crash, but don't start it
 --let $_expect_file_name= `select regexp_replace(@@tmpdir, '^.*/','')`
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/$_expect_file_name.expect
---exec echo "wait" > $_expect_file_name
+--write_line wait $_expect_file_name
 
 # Kill the connected server
 --disable_reconnect

mysql-test/include/kill_mysqld.inc

@@ -2,6 +2,6 @@
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/$_expect_file_name.expect
 
 --echo # Kill the server
---exec echo "wait" > $_expect_file_name
+--write_line wait $_expect_file_name
 --shutdown_server 0
 --source include/wait_until_disconnected.inc

mysql-test/include/rpl_start_server.inc

@@ -49,7 +49,7 @@ if ($rpl_server_parameters)
 --source include/rpl_connection.inc
 
 # Write file to make mysql-test-run.pl start up the server again
---exec echo "$_rpl_start_server_command" > $MYSQLTEST_VARDIR/tmp/mysqld.$rpl_server_number.expect
+--write_line "$_rpl_start_server_command"  $MYSQLTEST_VARDIR/tmp/mysqld.$rpl_server_number.expect
 
 if (!$rpl_server_error)
 {

mysql-test/include/rpl_stop_server.inc

@@ -44,7 +44,7 @@ if ($rpl_debug)
 
 # Write file to make mysql-test-run.pl expect the "crash", but don't start
 # it until it's told to
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.$rpl_server_number.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.$rpl_server_number.expect
 
 # Send shutdown to the connected server and give
 # it 60 seconds (of mysqltest's default) to die before zapping it

mysql-test/include/search_pattern_in_file.inc

@@ -38,7 +38,7 @@
 #    let SEARCH_FILE= $error_log;
 #    # Stop the server
 #    let $restart_file= $MYSQLTEST_VARDIR/tmp/mysqld.1.expect;
-#    --exec echo "wait" > $restart_file
+#    --write_line wait $restart_file
 #    --shutdown_server
 #    --source include/wait_until_disconnected.inc
 #

mysql-test/include/shutdown_mysqld.inc

@@ -24,7 +24,7 @@ if ($rpl_inited)
 # Write file to make mysql-test-run.pl expect the "crash", but don't start it
 --let $_expect_file_name= `select regexp_replace(@@tmpdir, '^.*/','')`
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/$_expect_file_name.expect
---exec echo "wait" > $_expect_file_name
+--write_line wait $_expect_file_name
 
 # Avoid warnings from connection threads that does not have time to exit
 --disable_query_log

mysql-test/include/start_mysqld.inc

@@ -21,7 +21,7 @@ if ($restart_bindir)
 
 if ($restart_parameters)
 {
-  --exec echo "$restart_cmd: $restart_parameters" > $_expect_file_name
+  --write_line "$restart_cmd: $restart_parameters" $_expect_file_name
   if (!$restart_noprint)
   {
     --replace_result $MYSQL_TEST_DIR MYSQL_TEST_DIR $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
@@ -34,7 +34,7 @@ if ($restart_parameters)
 }
 if (!$restart_parameters)
 {
-  --exec echo "$restart_cmd" > $_expect_file_name
+  --write_line "$restart_cmd" $_expect_file_name
   if ($restart_noprint < 2)
   {
     --exec echo "# $restart_cmd"

mysql-test/main/crash_commit_before.test

@@ -17,7 +17,7 @@ insert into t1 values(9);
 SET GLOBAL debug_dbug="d,crash_commit_before";
 
 # Write file to make mysql-test-run.pl expect crash and restart
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 # Run the crashing query
 --error 2013

mysql-test/main/empty_server_name-8224.test

@@ -3,10 +3,10 @@
 #
 --source include/not_embedded.inc
 create server '' foreign data wrapper w2 options (host '127.0.0.1');
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --shutdown_server
 --source include/wait_until_disconnected.inc
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 -- enable_reconnect
 -- source include/wait_until_connected_again.inc

mysql-test/main/host_cache_size_functionality.test

@@ -43,10 +43,10 @@ select @@global.Host_Cache_Size > 0;
 --echo # Restart server with Host_Cache_Size 1
 
 let $restart_file= $MYSQLTEST_VARDIR/tmp/mysqld.1.expect;
---exec echo "wait" > $restart_file
+--write_line wait $restart_file
 --shutdown_server
 --source include/wait_until_disconnected.inc
--- exec echo "restart:--host_cache_size=1  " > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line "restart:--host_cache_size=1  " $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 -- enable_reconnect
 -- source include/wait_until_connected_again.inc
 
@@ -142,10 +142,10 @@ SELECT Host_Cache_Size = @@SESSION.Host_Cache_Size;
 #--remove_file $MYSQL_TMP_DIR/bind_ip
 
 #let $restart_file= $MYSQLTEST_VARDIR/tmp/mysqld.1.expect;
-#--exec echo "wait" > $restart_file
+#--write_line wait $restart_file
 #--shutdown_server
 #--source include/wait_until_disconnected.inc
-#-- exec echo "restart:--bind-address=$bind_ip  " > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+#-- write_line "restart:--bind-address=$bind_ip  " $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 #-- enable_reconnect
 #-- source include/wait_until_connected_again.inc
 

mysql-test/main/init_file_set_password-7656.test

@@ -15,12 +15,12 @@ EOF
 
 --enable_reconnect
 
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 --shutdown_server
 --source include/wait_until_disconnected.inc
 
---exec echo "restart:--init-file=$MYSQLTEST_VARDIR/init.file  " > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line "restart:--init-file=$MYSQLTEST_VARDIR/init.file  " $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 --source include/wait_until_connected_again.inc
 select user,host,password,plugin,authentication_string from mysql.user where user='foo';

mysql-test/main/log_errchk.test

@@ -30,12 +30,12 @@
 --echo # Case 2: Starting server with fifo file as general log file
 --echo #         and slow query log file.
 # Restart server with fifo file as general log file.
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --shutdown_server
 --source include/wait_until_disconnected.inc
 --enable_reconnect
 # Write file to make mysql-test-run.pl start up the server again
---exec echo "restart: --general-log-file=$gen_log_file --slow-query-log-file=$slow_query_log_file" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line "restart: --general-log-file=$gen_log_file --slow-query-log-file=$slow_query_log_file" $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --source include/wait_until_connected_again.inc
 
 # Error 6 is reported, because the other end is closed

mysql-test/main/lowercase_fs_on.test

@@ -16,7 +16,7 @@ let SEARCH_FILE= $MYSQLTEST_VARDIR/log/my_restart.err;
 --remove_file $SEARCH_FILE
 
 #Shutdown the server
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --shutdown_server
 --source include/wait_until_disconnected.inc
 
@@ -30,7 +30,7 @@ let SEARCH_PATTERN= \[ERROR\] The server option \'lower_case_table_names\' is co
 --source include/search_pattern_in_file.inc
 
 #Restart the server
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --source include/wait_until_connected_again.inc
 
 #Cleanup

mysql-test/main/myisam_crash_before_flush_keys.test

@@ -26,14 +26,14 @@ INSERT INTO t1 VALUES (1,2),(2,3),(3,4),(4,5),(5,6);
 SET SESSION debug_dbug="d,crash_before_flush_keys";
 
 --echo # Write file to make mysql-test-run.pl expect crash
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 --echo # Run the crashing query
 --error 2013
 FLUSH TABLE t1;
 
 --echo # Write file to make mysql-test-run.pl start the server 
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 
 --echo # Turn on reconnect
 --enable_reconnect

mysql-test/main/mysql_client_test.test

@@ -25,7 +25,7 @@ call mtr.add_suppression(" IP address .* could not be resolved");
 # server or run mysql-test-run --debug mysql_client_test and check
 # var/log/mysql_client_test.trace
 
---exec echo "$MYSQL_CLIENT_TEST" > $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
+--write_line "$MYSQL_CLIENT_TEST" $MYSQLTEST_VARDIR/log/mysql_client_test.out.log
 --exec $MYSQL_CLIENT_TEST --getopt-ll-test=25600M >> $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
 
 # End of 4.1 tests

mysql-test/main/mysql_client_test_comp.test

@@ -12,7 +12,7 @@ SET @old_slow_query_log= @@global.slow_query_log;
 
 call mtr.add_suppression(" Error reading file './client_test_db/test_frm_bug.frm'");
 call mtr.add_suppression(" IP address .* could not be resolved");
---exec echo "$MYSQL_CLIENT_TEST" > $MYSQLTEST_VARDIR/log/mysql_client_test_comp.out.log 2>&1
+--write_line "$MYSQL_CLIENT_TEST" $MYSQLTEST_VARDIR/log/mysql_client_test_comp.out.log
 --exec $MYSQL_CLIENT_TEST --getopt-ll-test=25600M >> $MYSQLTEST_VARDIR/log/mysql_client_test_comp.out.log 2>&1
 
 # End of test

mysql-test/main/mysql_client_test_nonblock.test

@@ -19,7 +19,7 @@ call mtr.add_suppression(" IP address .* could not be resolved");
 # server or run mysql-test-run --debug mysql_client_test and check
 # var/log/mysql_client_test.trace
 
---exec echo "$MYSQL_CLIENT_TEST --non-blocking-api" > $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
+---write_line "$MYSQL_CLIENT_TEST --non-blocking-api" $MYSQLTEST_VARDIR/log/mysql_client_test.out.log
 --exec $MYSQL_CLIENT_TEST --non-blocking-api --getopt-ll-test=25600M >> $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
 
 # End of 4.1 tests

mysql-test/main/openssl_1.test

@@ -68,7 +68,7 @@ drop table t1;
 # Test that we can't open connection to server if we are using
 # a different cacert
 #
---exec echo "this query should not execute;" > $MYSQLTEST_VARDIR/tmp/test.sql
+--write_line "this query should not execute;" $MYSQLTEST_VARDIR/tmp/test.sql
 # Handle that openssl gives different error messages from YaSSL.
 --replace_regex /2026 TLS\/SSL error.*/2026 TLS\/SSL error: xxxx/
 --error 1

mysql-test/main/plugin_loaderr.test

@@ -13,14 +13,14 @@ FROM INFORMATION_SCHEMA.PLUGINS WHERE plugin_name = 'innodb';
 --echo #
 --echo # MDEV-6351 --plugin=force has no effect for built-in plugins
 --echo #
---exec echo "wait" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line wait $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --shutdown_server
 --source include/wait_until_disconnected.inc
 
 --error 1
 --exec $MYSQLD_CMD --innodb=force --innodb-page-size=6000 --disable-log-error
 
---exec echo "restart" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_line restart $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
 --enable_reconnect
 --source include/wait_until_connected_again.inc
 --disable_reconnect

mysql-test/main/shutdown.test

@@ -20,13 +20,13 @@ drop procedure try_shutdown;
 
 --let $_expect_file_name= `select regexp_replace(@@tmpdir, '^.*/','')`
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/$_expect_file_name.expect
---exec echo "wait" > $_expect_file_name
+--write_line wait $_expect_file_name
 
 --send shutdown
 --connection default
 --source include/wait_until_disconnected.inc
 
---exec echo "restart" > $_expect_file_name
+--write_line restart $_expect_file_name
 --enable_reconnect
 --source include/wait_until_connected_again.inc