MDEV-26713 UTF8 support on Windows, mysql_upgrade_service preparation

- Tolerate situation, when datadir for service seems invalid/non-existing
prior to upgrade. It could be that my.ini contains legacy ANSI characters
for the data directory. Those can't be read correctly by
mysql_upgrade_service, which uses a different ANSI codepage(UTF8)
.
- schedule upgrade_config_file at later stage, because once we
convert it to UTF-8 (followup patch), this will render config file uselss
with the older version of mariadbd.exe

- Refactor upgrade_conf_file.cc, prepare for UTF-8 conversion.

sql/mysql_upgrade_service.cc

@@ -374,13 +374,17 @@ static void change_service_config()
     Write datadir to my.ini, after converting  backslashes to 
     unix style slashes.
   */
-  strcpy_s(buf, MAX_PATH, service_properties.datadir);
-  for(i= 0; buf[i]; i++)
+  if (service_properties.datadir[0])
   {
-    if (buf[i] == '\\')
-      buf[i]= '/';
+    strcpy_s(buf, MAX_PATH, service_properties.datadir);
+    for (i= 0; buf[i]; i++)
+    {
+      if (buf[i] == '\\')
+        buf[i]= '/';
+    }
+    WritePrivateProfileString("mysqld", "datadir", buf,
+                              service_properties.inifile);
   }
-  WritePrivateProfileString("mysqld", "datadir",buf, service_properties.inifile);
 
   /*
     Remove basedir from defaults file, otherwise the service wont come up in 
@@ -465,13 +469,8 @@ int main(int argc, char **argv)
     }
   }
 
-  old_mysqld_exe_exists = (GetFileAttributes(service_properties.mysqld_exe) != INVALID_FILE_ATTRIBUTES);
-  log("Phase %d/%d: Fixing server config file%s", ++phase, max_phases, my_ini_exists ? "" : "(skipped)");
-
-  snprintf(my_ini_bck, sizeof(my_ini_bck), "%s.BCK", service_properties.inifile);
-  CopyFile(service_properties.inifile, my_ini_bck, FALSE);
-  upgrade_config_file(service_properties.inifile);
-
+  old_mysqld_exe_exists= (GetFileAttributes(service_properties.mysqld_exe) !=
+                          INVALID_FILE_ATTRIBUTES);
   bool do_start_stop_server = old_mysqld_exe_exists && initial_service_state != SERVICE_RUNNING;
 
   log("Phase %d/%d: Start and stop server in the old version, to avoid crash recovery %s", ++phase, max_phases,
@@ -526,6 +525,14 @@ int main(int argc, char **argv)
       start_duration_ms += 500;
     }
   }
+
+  log("Phase %d/%d: Fixing server config file%s", ++phase, max_phases,
+      my_ini_exists ? "" : "(skipped)");
+  snprintf(my_ini_bck, sizeof(my_ini_bck), "%s.BCK",
+           service_properties.inifile);
+  CopyFile(service_properties.inifile, my_ini_bck, FALSE);
+  upgrade_config_file(service_properties.inifile);
+
   /* 
     Start mysqld.exe as non-service skipping privileges (so we do not 
     care about the password). But disable networking and enable pipe 

sql/upgrade_conf_file.cc

@@ -158,51 +158,103 @@ static int cmp_strings(const void* a, const void *b)
   return strcmp((const char *)a, *(const char **)b);
 }
 
-/**
-  Convert file from a previous version, by removing
-*/
-int upgrade_config_file(const char *myini_path)
+
+#define MY_INI_SECTION_SIZE 32 * 1024 + 3
+
+
+int fix_section(const char *myini_path, const char *section_name,
+                bool is_server)
 {
-#define MY_INI_SECTION_SIZE 32*1024 +3
+  if (!is_server)
+    return 0;
+
   static char section_data[MY_INI_SECTION_SIZE];
-  for (const char *section_name : { "mysqld","server","mariadb" })
+  DWORD size= GetPrivateProfileSection(section_name, section_data,
+                                       MY_INI_SECTION_SIZE, myini_path);
+  if (size == MY_INI_SECTION_SIZE - 2)
   {
-    DWORD size = GetPrivateProfileSection(section_name, section_data, MY_INI_SECTION_SIZE, myini_path);
-    if (size == MY_INI_SECTION_SIZE - 2)
-    {
-      return -1;
-    }
+    return -1;
+  }
 
-    for (char *keyval = section_data; *keyval; keyval += strlen(keyval) + 1)
+  for (char *keyval= section_data; *keyval; keyval += strlen(keyval)+1)
+  {
+    char varname[256];
+    char *value;
+    char *key_end= strchr(keyval, '=');
+    if (!key_end)
+      key_end= keyval + strlen(keyval);
+
+    if (key_end - keyval > sizeof(varname))
+      continue;
+
+    value= key_end + 1;
+
+    // Check if variable should be removed from config.
+    // First, copy and normalize (convert dash to underscore) to  variable
+    // names
+    for (char *p= keyval, *q= varname;; p++, q++)
     {
-      char varname[256];
-      char *key_end = strchr(keyval, '=');
-      if (!key_end)
-        key_end = keyval+ strlen(keyval);
-
-      if (key_end - keyval > sizeof(varname))
-        continue;
-      // copy and normalize (convert dash to underscore) to  variable names
-      for (char *p = keyval, *q = varname;; p++,q++)
+      if (p == key_end)
       {
-        if (p == key_end)
-        {
-          *q = 0;
-          break;
-        }
-        *q = (*p == '-') ? '_' : *p;
+        *q= 0;
+        break;
       }
-      const char *v = (const char *)bsearch(varname, removed_variables, sizeof(removed_variables) / sizeof(removed_variables[0]),
-        sizeof(char *), cmp_strings);
+      *q= (*p == '-') ? '_' : *p;
+    }
+    const char *v= (const char *) bsearch(varname, removed_variables, sizeof(removed_variables) / sizeof(removed_variables[0]),
+                                          sizeof(char *), cmp_strings);
 
-      if (v)
-      {
-        fprintf(stdout, "Removing variable '%s' from config file\n", varname);
-        // delete variable
-        *key_end = 0;
-        WritePrivateProfileString(section_name, keyval, 0, myini_path);
-      }
+    if (v)
+    {
+      fprintf(stdout, "Removing variable '%s' from config file\n", varname);
+      // delete variable
+      *key_end= 0;
+      WritePrivateProfileString(section_name, keyval, 0, myini_path);
     }
   }
   return 0;
 }
+
+static bool is_mariadb_section(const char *name, bool *is_server)
+{
+  if (strncmp(name, "mysql", 5)
+      && strncmp(name, "mariadb", 7)
+      && strcmp(name, "client")
+      && strcmp(name, "client-server")
+      && strcmp(name, "server"))
+  {
+    return false;
+  }
+
+  for (const char *section_name : {"mysqld", "server", "mariadb"})
+    if (*is_server= !strcmp(section_name, name))
+      break;
+
+  return *is_server;
+}
+
+
+/**
+  Convert file from a previous version, by removing obsolete variables
+  Also, fix values to be UTF8, if MariaDB is running in utf8 mode
+*/
+int upgrade_config_file(const char *myini_path)
+{
+  static char all_sections[MY_INI_SECTION_SIZE];
+  int sz= GetPrivateProfileSectionNamesA(all_sections, MY_INI_SECTION_SIZE,
+                                         myini_path);
+  if (!sz)
+    return 0;
+  if (sz > MY_INI_SECTION_SIZE - 2)
+  {
+    fprintf(stderr, "Too many sections in config file\n");
+    return -1;
+  }
+  for (char *section= all_sections; *section; section+= strlen(section) + 1)
+  {
+    bool is_server_section;
+    if (is_mariadb_section(section, &is_server_section))
+      fix_section(myini_path, section, is_server_section);
+  }
+  return 0;
+}

sql/winservice.c

@@ -134,6 +134,20 @@ static void get_datadir_from_ini(const char *ini, char *service_name, char *data
 }
 
 
+static int fix_and_check_datadir(mysqld_service_properties *props)
+{
+  normalize_path(props->datadir, MAX_PATH);
+  /* Check if datadir really exists */
+  if (GetFileAttributes(props->datadir) != INVALID_FILE_ATTRIBUTES)
+    return 0;
+  /*
+    It is possible, that datadir contains some unconvertable character.
+    We just pretend not to know what's the data directory
+  */
+  props->datadir[0]= 0;
+  return 0;
+}
+
 /*
   Retrieve some properties from windows mysqld service binary path.
   We're interested in ini file location and datadir, and also in version of
@@ -284,16 +298,9 @@ int get_mysql_service_properties(const wchar_t *bin_path,
     }
   }
 
-  if (props->datadir[0])
-  {
-    normalize_path(props->datadir, MAX_PATH);
-    /* Check if datadir really exists */
-    if (GetFileAttributes(props->datadir) == INVALID_FILE_ATTRIBUTES)
-      goto end;
-  }
-  else
+  if (props->datadir[0] == 0 || fix_and_check_datadir(props))
   {
-    /* There is no datadir in ini file,  bail out.*/
+    /* There is no datadir in ini file, or non-existing dir, bail out.*/
     goto end;
   }