Bug #17076131 MYSQLDUMP FAILS WHEN ERR LOG ON RUNNING SERVER IS DELETED ON WINDOWS

Problem:
As the title mentions, on windows mysqldump tool is creating the dump file 
without the content (tables, views etc) of a database that is dumped when the 
error log file is deleted (by the user). Similar behaviour is not happening 
on Linux flavours. The difference is due to the difference in handling of the 
deleted files. In Windows, the line "if (flush_logs || opt_delete_master_logs)"
in main.c of mysqldump is returning error whereas on linux this line is passing

Solution:
The core problem is that, in Windows, the new error log file is being created but
the old file descriptor which is associated with both stdout and stderr stream
is not being closed by the program. So a retry logic has been implemented where
we close the error log's file descriptor (associated open fds of stderr and
stdout) in the first attempt and open a new file and associating it with
stdout/stderr streams.

Author: Anirudh Mangipudi

mysql-test/r/bug17076131.result

@@ -0,0 +1,12 @@
+#
+# Bug#17076131 MYSQLDUMP FAILS WHEN ERR LOG ON RUNNING SERVER IS
+#              DELETED ON WINDOWS
+#
+# Creating file aliases.
+# Executing mysqldump normally.
+# Removing Error_log file.
+# Executing mysqldump after deleting error_log file.
+# Checking diff of the 2 dumps.
+# No Difference found.
+# Clean Up.
+# End of Test.

mysql-test/t/bug17076131-master.opt

@@ -0,0 +1,2 @@
+--no-console
+--log-error=$MYSQLTEST_VARDIR/tmp/mysql.err

mysql-test/t/bug17076131.test

@@ -0,0 +1,28 @@
+--echo #
+--echo # Bug#17076131 MYSQLDUMP FAILS WHEN ERR LOG ON RUNNING SERVER IS
+--echo #              DELETED ON WINDOWS
+--echo #
+
+--source include/not_embedded.inc
+
+--echo # Creating file aliases.
+let $dump_with_err_log=$MYSQLTEST_VARDIR/tmp/bug17076131_with_err_log.sql;
+let $dump_without_err_log=$MYSQLTEST_VARDIR/tmp/bug17076131_without_err_log.sql;
+
+--echo # Executing mysqldump normally.
+--exec $MYSQL_DUMP --extended-insert --flush-logs --add-drop-database --add-drop-table  --force --databases --skip-dump-date mysql  > $dump_with_err_log
+
+--echo # Removing Error_log file.
+--remove_file $MYSQLTEST_VARDIR/tmp/mysql.err
+
+--echo # Executing mysqldump after deleting error_log file.
+--exec $MYSQL_DUMP --extended-insert --flush-logs --add-drop-database --add-drop-table  --force --databases --skip-dump-date mysql  > $dump_without_err_log
+
+--echo # Checking diff of the 2 dumps.
+--diff_files $dump_with_err_log $dump_without_err_log
+--echo # No Difference found.
+
+--echo # Clean Up.
+--remove_file $dump_with_err_log
+--remove_file $dump_without_err_log
+--echo # End of Test.

mysys/my_fopen.c

@@ -120,7 +120,10 @@ static FILE *my_win_freopen(const char *path, const char *mode, FILE *stream)
                         FILE_SHARE_DELETE, NULL,
                         OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL,
                         NULL)) == INVALID_HANDLE_VALUE)
+  {
+    _close(fd);
     return NULL;
+  }
 
   if ((handle_fd= _open_osfhandle((intptr_t)osfh,
                                   _O_APPEND | _O_TEXT)) == -1)

sql/log.cc

@@ -2206,10 +2206,20 @@ void sql_perror(const char *message)
 extern "C" my_bool reopen_fstreams(const char *filename,
                                    FILE *outstream, FILE *errstream)
 {
+  int retries= 2, errors= 0;
+
+  do
+  {
+    errors= 0;
     if (errstream && !my_freopen(filename, "a", errstream))
-      return true;
+      errors++;
     if (outstream && !my_freopen(filename, "a", outstream))
-      return true;
+      errors++;
+  }
+  while (retries-- && errors);
+
+  if (errors)
+    return true;
 
   /* The error stream must be unbuffered. */
   if (errstream)