Re: [patch, libgfortran] PR107031 - endfile truncates file at wrong position

[Harald Anlauf]

Hi Jerry,

Am 26.03.24 um 04:18 schrieb Jerry D:

Hi all,

There has been a bit of discussio on which way to go on this.

I took a look today and this trivial patch gives the behavior concluded 
on Fortran Discourse. See the bugzilla for all the relevant information.


Regresion tested on x86-64.

I will do the appropriate changelog.

OK for trunk?

Attached is a new test case and the patch here:

diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
index 2bc05b293f8..d169961f997 100644
--- a/libgfortran/io/file_pos.c
+++ b/libgfortran/io/file_pos.c
@@ -352,7 +352,6 @@ st_endfile (st_parameter_filepos *fpp)
   dtp.common = fpp->common;
   memset (&dtp.u.p, 0, sizeof (dtp.u.p));
   dtp.u.p.current_unit = u;
- next_record (&dtp, 1);
     }

    unit_truncate (u, stell (u->s), &fpp->common);


this is OK from my side.

Given the discussion on "dg-do  run", wouldn't this be a perfect
example where it is sufficient to run the testcase just once?

The change is in libgfortran, not in the frontend or middle-end.

Thanks for the patch!

Harald

[patch, libgfortran] PR107031 - endfile truncates file at wrong position

[Jerry D]

Hi all,

There has been a bit of discussio on which way to go on this.

I took a look today and this trivial patch gives the behavior concluded 
on Fortran Discourse. See the bugzilla for all the relevant information.


Regresion tested on x86-64.

I will do the appropriate changelog.

OK for trunk?

Attached is a new test case and the patch here:

diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
index 2bc05b293f8..d169961f997 100644
--- a/libgfortran/io/file_pos.c
+++ b/libgfortran/io/file_pos.c
@@ -352,7 +352,6 @@ st_endfile (st_parameter_filepos *fpp)
  dtp.common = fpp->common;
  memset (&dtp.u.p, 0, sizeof (dtp.u.p));
  dtp.u.p.current_unit = u;
- next_record (&dtp, 1);
}

   unit_truncate (u, stell (u->s), &fpp->common);
! { dg-do run }
! PR107031 Check that endfile truncates at end of record 5.
program test_truncate
integer :: num_rec, tmp, i, nr, j
open(10, file="in.dat", action='readwrite')

do i=1,10
  write(10, *) i
end do

rewind (10)

num_rec = 5
i = 1
ioerr = 0
do while (i <= num_rec .and. ioerr == 0)
read(10, *, iostat=ioerr) tmp
i = i + 1
enddo
endfile(10)
rewind (10)
i = 0
ioerr = 0
do while (i <= num_rec + 1 .and. ioerr == 0)
  read(10, *, iostat=ioerr) j
  i = i + 1
end do
close(10, status='delete')
if (i - 1 /= 5) stop 1
end program test_truncate