BUG#29207 - archive table reported as corrupt by check table (P1)

CHECK TABLE against ARCHIVE table may falsely report table corruption,
or cause server crash.

Fixed by using proper buffer for CHECK TABLE.

Affects both 5.0 and 5.1.


mysql-test/r/archive.result:
  A test case for BUG#28916.
mysql-test/t/archive.test:
  A test case for BUG#28916.
sql/ha_archive.cc:
  We call Field::get_length() from get_row(). Field::get_length() assumes
  that the row was read into table->record[0] buffer, which is not the
  case when we check a table. As a result we get wrongly initialized
  blob length.
  
  Use table->record[0] as record buffer for check table instead.

mysql-test/r/archive.result

@@ -12364,3 +12364,10 @@ select * from t1;
 i
 1
 drop table t1;
+create table t1(a longblob) engine=archive;
+insert into t1 set a='';
+insert into t1 set a='a';
+check table t1 extended;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+drop table t1;

mysql-test/t/archive.test

@@ -1374,3 +1374,12 @@ insert into t1 values (1);
 repair table t1 use_frm;
 select * from t1;
 drop table t1;
+
+#
+# BUG#29207 - archive table reported as corrupt by check table
+#
+create table t1(a longblob) engine=archive;
+insert into t1 set a='';
+insert into t1 set a='a';
+check table t1 extended;
+drop table t1;

sql/ha_archive.cc

@@ -1205,7 +1205,6 @@ bool ha_archive::is_crashed() const
 int ha_archive::check(THD* thd, HA_CHECK_OPT* check_opt)
 {
   int rc= 0;
-  byte *buf; 
   const char *old_proc_info=thd->proc_info;
   ha_rows count= share->rows_recorded;
   DBUG_ENTER("ha_archive::check");
@@ -1214,26 +1213,14 @@ int ha_archive::check(THD* thd, HA_CHECK_OPT* check_opt)
   /* Flush any waiting data */
   gzflush(share->archive_write, Z_SYNC_FLUSH);
 
-  /* 
-    First we create a buffer that we can use for reading rows, and can pass
-    to get_row().
-  */
-  if (!(buf= (byte*) my_malloc(table->s->reclength, MYF(MY_WME))))
-    rc= HA_ERR_OUT_OF_MEM;
-
   /*
     Now we will rewind the archive file so that we are positioned at the 
     start of the file.
   */
-  if (!rc)
   read_data_header(archive);
-
-  if (!rc)
-    while (!(rc= get_row(archive, buf)))
+  while (!(rc= get_row(archive, table->record[0])))
     count--;
 
-  my_free((char*)buf, MYF(0));
-
   thd->proc_info= old_proc_info;
 
   if ((rc && rc != HA_ERR_END_OF_FILE) || count)