[Bug libfortran/24700] Bad write after backing up from end of file

["jvdelisle at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #1 from jvdelisle at gcc dot gnu dot org  2005-11-06 23:58 -------
Testing that patch gives the following results.  I will put together a test
case and commit this as obvious unless there are objections.

hex dump of TEST file created using gfortran 4.0.1 gives, with no patch:

$ xxd TEST
0000000: 0800 0000 0000 0000 2a2a 5445 5354 2a2a  ........**TEST**
0000010: 0800 0000 0000 0000 0800 0000 0000 0000  ................
0000020: 2a2a 5445 5354 2a2a 0800 0000 0000 0000  **TEST**........

With gfortran 4.1 we get:

$ xxd TEST
0000000: 0800 0000 0000 0000 2a2a 5445 5354 2a2a  ........**TEST**
0000010: 0800 0000 0000 0000 2a2a 5445 5354 2a2a  ........**TEST**
0000020: ffff ffff ffff ff7f                      ........

With Georgy's patch on 4.0.3:

$ xxd TEST
0000000: 0800 0000 0000 0000 2a2a 5445 5354 2a2a  ........**TEST**
0000010: 0800 0000 0000 0000 0800 0000 0000 0000  ................
0000020: 2a2a 5445 5354 2a2a 0800 0000 0000 0000  **TEST**........

With Georgy's patch on 4.1:

$ xxd TEST
0000000: 0800 0000 0000 0000 2a2a 5445 5354 2a2a  ........**TEST**
0000010: 0800 0000 0000 0000 0800 0000 0000 0000  ................
0000020: 2a2a 5445 5354 2a2a 0800 0000 0000 0000  **TEST**........

So it appears we had a regression from 4.0.1 in there somehow and did not catch
it. 

Regards

Jerry


-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-11-06 23:58:36
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24700