Fixed bug #31036: Using order by with archive table crashes server.

1. Memory overrun have been fixed.
2. Server failure on assertion has been fixed.

mysql-test/r/archive.result

@@ -12682,3 +12682,7 @@ check table t1 extended;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 drop table t1;
+CREATE TABLE t1(a VARCHAR(510)) ENGINE = ARCHIVE;
+INSERT INTO t1(a) VALUES ('');
+SELECT * FROM t1 ORDER BY a;
+DROP TABLE t1;

mysql-test/t/archive.test

@@ -1559,3 +1559,25 @@ insert into t1 set a='';
 insert into t1 set a='a';
 check table t1 extended;
 drop table t1;
+
+#
+# BUG#31036 - Using order by with archive table crashes server
+#
+
+CREATE TABLE t1(a VARCHAR(510)) ENGINE = ARCHIVE;
+
+let $bug31036=41;
+--disable_query_log
+while($bug31036)
+{
+  INSERT INTO t1(a) VALUES (REPEAT('a', 510));
+  dec $bug31036;
+}
+--enable_query_log
+INSERT INTO t1(a) VALUES ('');
+
+--disable_result_log
+SELECT * FROM t1 ORDER BY a;
+--enable_result_log
+
+DROP TABLE t1;

storage/archive/azio.c

@@ -681,8 +681,8 @@ my_off_t azseek (s, offset, whence)
     /* There was a zmemzero here if inbuf was null -Brian */
     while (offset > 0)  
     {
-      uInt size = AZ_BUFSIZE_WRITE;
-      if (offset < AZ_BUFSIZE_WRITE) size = (uInt)offset;
+      uInt size = AZ_BUFSIZE_READ;
+      if (offset < AZ_BUFSIZE_READ) size = (uInt)offset;
 
       size = azwrite(s, s->inbuf, size);
       if (size == 0) return -1L;
@@ -725,11 +725,11 @@ my_off_t azseek (s, offset, whence)
   }
   while (offset > 0)  {
     int error;
-    unsigned int size = AZ_BUFSIZE_READ;
-    if (offset < AZ_BUFSIZE_READ) size = (int)offset;
+    unsigned int size = AZ_BUFSIZE_WRITE;
+    if (offset < AZ_BUFSIZE_WRITE) size = (int)offset;
 
     size = azread(s, s->outbuf, size, &error);
-    if (error <= 0) return -1L;
+    if (error < 0) return -1L;
     offset -= size;
   }
   return s->out;

storage/archive/ha_archive.cc

@@ -1241,8 +1241,8 @@ int ha_archive::rnd_pos(uchar * buf, uchar *pos)
   DBUG_ENTER("ha_archive::rnd_pos");
   ha_statistic_increment(&SSV::ha_read_rnd_next_count);
   current_position= (my_off_t)my_get_ptr(pos, ref_length);
-  (void)azseek(&archive, current_position, SEEK_SET);
-
+  if (azseek(&archive, current_position, SEEK_SET) < 0)
+    DBUG_RETURN(HA_ERR_CRASHED_ON_USAGE);
   DBUG_RETURN(get_row(&archive, buf));
 }