MDEV-9044 Binlog corruption in Galera

unit test for the IO_CACHE bug

unittest/sql/mf_iocache-t.cc

@@ -112,6 +112,8 @@ void temp_io_cache()
   uchar buf[CACHE_SIZE + 200];
   memset(buf, FILL, sizeof(buf));
 
+  diag("temp io_cache with%s encryption", encrypt_tmp_files?"":"out");
+
   init_io_cache_encryption();  
   
   res= open_cached_file(&info, 0, 0, CACHE_SIZE, 0);
@@ -137,7 +139,7 @@ void temp_io_cache()
 
   res= my_pread(info.file, buf, 50, 50, MYF(MY_NABP));
   ok(res == 0 && data_bad(buf, 50) == encrypt_tmp_files,
-     "check encryption, file must be %sreadable", encrypt_tmp_files ?"un":"");
+     "file must be %sreadable", encrypt_tmp_files ?"un":"");
 
   res= my_b_read(&info, buf, 50) || data_bad(buf, 50);
   ok(res == 0 && info.pos_in_file == 0, "small read" INFO_TAIL);
@@ -148,18 +150,58 @@ void temp_io_cache()
   close_cached_file(&info);
 }
 
+void mdev9044()
+{
+  int res;
+  uchar buf[CACHE_SIZE + 200];
+
+  diag("MDEV-9044 Binlog corruption in Galera");
+
+  res= open_cached_file(&info, 0, 0, CACHE_SIZE, 0);
+  ok(res == 0, "open_cached_file" INFO_TAIL);
+
+  res= my_b_write(&info, USTRING_WITH_LEN("first write\0"));
+  ok(res == 0, "first write" INFO_TAIL);
+
+  res= my_b_flush_io_cache(&info, 1);
+  ok(res == 0, "flush" INFO_TAIL);
+
+  res= reinit_io_cache(&info, WRITE_CACHE, 0, 0, 0);
+  ok(res == 0, "reinit WRITE_CACHE" INFO_TAIL);
+
+  res= my_b_write(&info, USTRING_WITH_LEN("second write\0"));
+  ok(res == 0, "second write" INFO_TAIL );
+
+  res= reinit_io_cache(&info, READ_CACHE, 0, 0, 0);
+  ok(res == 0, "reinit READ_CACHE" INFO_TAIL);
+
+  res= my_b_fill(&info);
+  ok(res == 0, "fill" INFO_TAIL);
+
+  res= reinit_io_cache(&info, READ_CACHE, 0, 0, 0);
+  ok(res == 0, "reinit READ_CACHE" INFO_TAIL);
+
+  res= my_b_read(&info, buf, sizeof(buf));
+  ok(res == 1 && strcmp((char*)buf, "second write") == 0, "read '%s'", buf);
+
+  close_cached_file(&info);
+}
+
 int main(int argc __attribute__((unused)),char *argv[])
 {
   MY_INIT(argv[0]);
-  plan(20);
+  plan(29);
 
-  /* temp files */
-  encrypt_tmp_files= 0;
+  /* temp files with and without encryption */
+  encrypt_tmp_files= 1;
   temp_io_cache();
 
-  encrypt_tmp_files= 1;
+  encrypt_tmp_files= 0;
   temp_io_cache();
 
+  /* regression tests */
+  mdev9044();
+
   my_end(0);
   return exit_status();
 }