[Bug libfortran/45723] New: opening /dev/null for appending writes

[Bug libfortran/45723] New: opening /dev/null for appending writes

[Joost dot VandeVondele at pci dot uzh dot ch]

I'm wondering if the following open statement should really fail. I have no
strong opinion, but it would be convenient if it 'just' worked, like you can
open an non-existing file and 'append'.

I guess it is related to the fact that /dev/null can't be seeked.

> cat test.f90
 OPEN(UNIT=7,FILE="/dev/null",FORM="FORMATTED",POSITION="APPEND",IOSTAT=istat)
 IF (istat.NE.0) STOP 1
 END


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           Summary: opening /dev/null for appending writes
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Joost dot VandeVondele at pci dot uzh dot ch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[Joost dot VandeVondele at pci dot uzh dot ch]

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Joost dot VandeVondele at pci dot uzh dot ch changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[jvdelisle at gcc dot gnu dot org]

------- Comment #1 from jvdelisle at gcc dot gnu dot org  2010-09-19 20:01 -------
This is an OS specific error.  libgfortran is attempting to seek to the end of
the file to prepare for appending.  Obviously, one can not seek /dev/null.

I will see if we can detect that the file is unseekable and if that is the case
we can start appending AS-IS.


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jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jvdelisle at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-09-19 20:01:18
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[jvdelisle at gcc dot gnu dot org]

------- Comment #2 from jvdelisle at gcc dot gnu dot org  2010-09-20 04:46 -------
Created an attachment (id=21841)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21841&action=view)
Possible patch

This patch passes regression testing. Don't seek if filesize is zero.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[Joost dot VandeVondele at pci dot uzh dot ch]

------- Comment #3 from Joost dot VandeVondele at pci dot uzh dot ch  2010-09-20 06:30 -------
(In reply to comment #2)
> Created an attachment (id=21841)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21841&action=view) [edit]
> Possible patch
> 
> This patch passes regression testing. Don't seek if filesize is zero.
> 
seems like a clean solution... thanks.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[jvdelisle at gcc dot gnu dot org]

------- Comment #4 from jvdelisle at gcc dot gnu dot org  2010-09-22 03:10 -------
Subject: Bug 45723

Author: jvdelisle
Date: Wed Sep 22 03:10:24 2010
New Revision: 164507

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164507
Log:
2010-09-21  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libfortran/45723
        * io/open.c (new_unit): On POSITION_APPEND don't seek if file length is
        zero.

Modified:
    trunk/libgfortran/ChangeLog
    trunk/libgfortran/io/open.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[Joost dot VandeVondele at pci dot uzh dot ch]

------- Comment #5 from Joost dot VandeVondele at pci dot uzh dot ch  2010-09-22 11:31 -------
I guess this bug can be closed unless you intend backporting to earlier
versions.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723

[Bug libfortran/45723] opening /dev/null for appending writes

[jvdelisle at gcc dot gnu dot org]

------- Comment #6 from jvdelisle at gcc dot gnu dot org  2010-09-22 15:07 -------
I don't see a need to backport. Closing


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jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45723