branches/5.1:

Fix Bug#34300 Tinyblob & tinytext fields currupted after export/import and alter in 5.1

Copy the BLOB fields, that are stored internally, to a safe place
(prebuilt->blob_heap) when converting a row from InnoDB format to
MySQL format in row_sel_store_mysql_rec().

The bug was introduced in:

 ------------------------------------------------------------------------
 r587 | osku | 2006-05-23 15:35:58 +0300 (Tue, 23 May 2006) | 3 lines
 
 Optimize BLOB selects by using prebuilt->blob_heap directly instead of first
 reading BLOB data to a temporary heap and then copying it to
 prebuilt->blob_heap.
 ------------------------------------------------------------------------

Approved by:	Heikki

mysql-test/innodb_bug34300.result

+f4	f8
+xxx	zzz
+f4	f8
+xxx	zzz

mysql-test/innodb_bug34300.test

+#
+# Bug#34300 Tinyblob & tinytext fields currupted after export/import and alter in 5.1
+# http://bugs.mysql.com/34300
+#
+
+-- source include/have_innodb.inc
+
+-- disable_query_log
+-- disable_result_log
+
+SET @@max_allowed_packet=16777216;
+
+DROP TABLE IF EXISTS bug34300;
+CREATE TABLE bug34300 (
+  f4 TINYTEXT,
+  f6 MEDIUMTEXT,
+  f8 TINYBLOB
+) ENGINE=InnoDB;
+
+INSERT INTO bug34300 VALUES ('xxx', repeat('a', 8459264), 'zzz');
+
+-- enable_result_log
+
+SELECT f4, f8 FROM bug34300;
+
+ALTER TABLE bug34300 ADD COLUMN (f10 INT);
+
+SELECT f4, f8 FROM bug34300;
+
+DROP TABLE bug34300;

row/row0sel.c

@@ -2643,6 +2643,25 @@ row_sel_store_mysql_rec(
 
 			data = rec_get_nth_field(rec, offsets,
 						 templ->rec_field_no, &len);
+
+			if (UNIV_UNLIKELY(templ->type == DATA_BLOB)
+			    && len != UNIV_SQL_NULL) {
+
+				/* It is a BLOB field locally stored in the
+				InnoDB record: we MUST copy its contents to
+				prebuilt->blob_heap here because later code
+				assumes all BLOB values have been copied to a
+				safe place. */
+
+				if (prebuilt->blob_heap == NULL) {
+					prebuilt->blob_heap = mem_heap_create(
+						UNIV_PAGE_SIZE);
+				}
+
+				data = memcpy(mem_heap_alloc(
+						prebuilt->blob_heap, len),
+						data, len);
+			}
 		}
 
 		if (len != UNIV_SQL_NULL) {