re PR libfortran/19478 (reading back from /dev/null)

	PR fortran/19478
	* io/unix.c (fd_truncate): update positions when ftruncate
	fails (like writing to /dev/null).
	* gfortran.dg/dev_null.f90: New test.

From-SVN: r99570

gcc/testsuite/ChangeLog

+2005-05-11  Bud Davis  <bdavis@gfortran.org>
+
+	* gfortran.dg/dev_null.f90: New test.
+
 2005-05-11  Richard Earnshaw  <richard.earnshaw@arm.com>
 
 	* gcc.dg/arm-vfp1.c: Revert last change.

gcc/testsuite/gfortran.dg/dev_null.f90

+! { dg-do run }
+! pr19478 read from /dev/null
+! Thomas.Koenig@online.de
+      character*20 foo
+      open(10,file="/dev/null")
+      write(10,'(A)') "Hello"
+      rewind(10)
+      read(10,'(A)',end=100) foo
+      call abort
+ 100  continue
+      end

libgfortran/ChangeLog

+2005-05-11  Bud Davis  <bdavis@gfortran.org>
+
+	PR fortran/19478
+	* io/unix.c (fd_truncate): update positions when ftruncate
+	fails (like writing to /dev/null).
+
 2005-05-10  Francois-Xavier Coudert  <coudert@clipper.ens.fr>
 
 	PR libfortran/21471

libgfortran/io/unix.c

@@ -515,13 +515,15 @@ fd_truncate (unix_stream * s)
 
 #ifdef HAVE_FTRUNCATE
   if (ftruncate (s->fd, s->logical_offset))
-    return FAILURE;
 #else
 #ifdef HAVE_CHSIZE
   if (chsize (s->fd, s->logical_offset))
-    return FAILURE;
 #endif
 #endif
+    {
+      s->physical_offset = s->file_length = 0;
+      return FAILURE;
+    }
 
   s->physical_offset = s->file_length = s->logical_offset;