InnoDB: Backport fil_path_to_mysql_datadir from MySQL 4.1.x

innobase/fil/fil0fil.c:
  Backport fil_path_to_mysql_datadir from 4.1
innobase/include/fil0fil.h:
  Backport fil_path_to_mysql_datadir from 4.1
sql/ha_innodb.cc:
  Backport fil_path_to_mysql_datadir from 4.1

innobase/fil/fil0fil.c

@@ -77,6 +77,11 @@ out of the LRU-list and keep a count of pending operations. When an operation
 completes, we decrement the count and return the file node to the LRU-list if
 the count drops to zero. */
 
+/* When mysqld is run, the default directory "." is the mysqld datadir,
+but in the MySQL Embedded Server Library and ibbackup it is not the default
+directory, and we must set the base file path explicitly */
+const char*	fil_path_to_mysql_datadir	= ".";
+
 ulint	fil_n_pending_log_flushes		= 0;
 ulint	fil_n_pending_tablespace_flushes	= 0;
 

innobase/include/fil0fil.h

@@ -16,6 +16,11 @@ Created 10/25/1995 Heikki Tuuri
 #include "ut0byte.h"
 #include "os0file.h"
 
+/* When mysqld is run, the default directory "." is the mysqld datadir, but in
+ibbackup we must set it explicitly; the path must NOT contain the trailing
+'/' or '\' */
+extern const char*	fil_path_to_mysql_datadir;
+
 /* 'null' (undefined) page offset in the context of file spaces */
 #define	FIL_NULL	ULINT32_UNDEFINED
 

sql/ha_innodb.cc

@@ -714,6 +714,7 @@ innobase_init(void)
 
 	if (mysql_embedded) {
 		default_path = mysql_real_data_home;
+		fil_path_to_mysql_datadir = mysql_real_data_home;
 	} else {
 	  	/* It's better to use current lib, to keep paths short */
 	  	current_dir[0] = FN_CURLIB;