Merge mysql.com:/home/mydev/mysql-4.1-bug5964

into mysql.com:/home/mydev/mysql-4.1-4100

include/my_sys.h

@@ -609,6 +609,7 @@ extern uint dirname_part(my_string to,const char *name);
 extern uint dirname_length(const char *name);
 #define base_name(A) (A+dirname_length(A))
 extern int test_if_hard_path(const char *dir_name);
+extern my_bool has_path(const char *name);
 extern char *convert_dirname(char *to, const char *from, const char *from_end);
 extern void to_unix_path(my_string name);
 extern my_string fn_ext(const char *name);

myisammrg/myrg_open.c

@@ -80,7 +80,7 @@ MYRG_INFO *myrg_open(const char *name, int mode, int handle_locking)
       continue;		/* Skip comments */
     }
 
-    if (!test_if_hard_path(buff))
+    if (!has_path(buff))
     {
       VOID(strmake(name_buff+dir_length,buff,
                    sizeof(name_buff)-1-dir_length));

mysys/my_getwd.c

@@ -192,3 +192,25 @@ int test_if_hard_path(register const char *dir_name)
   return FALSE;
 #endif
 } /* test_if_hard_path */
+
+
+/*
+  Test if a name contains an (absolute or relative) path.
+
+  SYNOPSIS
+    has_path()
+    name                The name to test.
+
+  RETURN
+    TRUE        name contains a path.
+    FALSE       name does not contain a path.
+*/
+
+my_bool has_path(const char *name)
+{
+  return test(strchr(name, FN_LIBCHAR))
+#ifdef FN_DEVCHAR
+    || test(strchr(name, FN_DEVCHAR))
+#endif
+    ;
+}

sql/ha_myisammrg.cc

@@ -381,6 +381,7 @@ int ha_myisammrg::create(const char *name, register TABLE *form,
   char buff[FN_REFLEN],**table_names,**pos;
   TABLE_LIST *tables= (TABLE_LIST*) create_info->merge_list.first;
   THD *thd= current_thd;
+  uint dirlgt= dirname_length(name);
   DBUG_ENTER("ha_myisammrg::create");
 
   if (!(table_names= (char**) thd->alloc((create_info->merge_list.elements+1)*
@@ -394,10 +395,29 @@ int ha_myisammrg::create(const char *name, register TABLE *form,
       tbl= find_temporary_table(thd, tables->db, tables->real_name);
     if (!tbl)
     {
-      uint length= my_snprintf(buff,FN_REFLEN,"%s%s/%s",
-			       mysql_real_data_home,
+      /*
+        Construct the path to the MyISAM table. Try to meet two conditions:
+        1.) Allow to include MyISAM tables from different databases, and
+        2.) allow for moving DATADIR around in the file system.
+        The first means that we need paths in the .MRG file. The second
+        means that we should not have absolute paths in the .MRG file.
+        The best, we can do, is to use 'mysql_data_home', which is '.'
+        in mysqld and may be an absolute path in an embedded server.
+        This means that it might not be possible to move the DATADIR of
+        an embedded server without changing the paths in the .MRG file.
+      */
+      uint length= my_snprintf(buff, FN_REFLEN, "%s/%s/%s", mysql_data_home,
 			       tables->db, tables->real_name);
-      if (!(table_name= thd->strmake(buff, length)))
+      /*
+        If a MyISAM table is in the same directory as the MERGE table,
+        we use the table name without a path. This means that the
+        DATADIR can easily be moved even for an embedded server as long
+        as the MyISAM tables are from the same database as the MERGE table.
+      */
+      if ((dirname_length(buff) == dirlgt) && ! memcmp(buff, name, dirlgt))
+        table_name= tables->real_name;
+      else
+        if (! (table_name= thd->strmake(buff, length)))
           DBUG_RETURN(HA_ERR_OUT_OF_MEM);
     }
     else