* io/rewind.c (st_rewind): Reset unit to read mode.

testsuite/
	* gfortran.dg/rewind_1.f90: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@86659 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 18f8037..20b6267 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2004-08-27  Paul Brook  <paul@codesourcery.com>
+
+       * gfortran.dg/rewind_1.f90: New test.
+
 2004-08-27  Bud Davis  <bdavis9659@comcast.net>
 
        PR fortran/16597

diff --git a/gcc/testsuite/gfortran.dg/rewind_1.f90 b/gcc/testsuite/gfortran.dg/rewind_1.f90
new file mode 100644 (file)
index 0000000..cbd2ef1
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/rewind_1.f90
@@ -0,0 +1,18 @@
+! { dg-do run }
+! Check that rewind doesn't delete a file.
+! Writing to the file truncates it at the end of the current record.  Out
+! IO library was defering the actual truncation until the file was rewound.
+! A second rewind would then (incorrectly) think the file had just been
+! written to, and truncate the file to zero length.
+program foo
+  character*11 s
+  open(unit=11, status="SCRATCH")
+  write(11, '(a11)') "Hello World"
+  rewind(11)
+  rewind(11)
+  s = ""
+  read(11, '(a11)') s
+  close(11)
+  if (s .ne. "Hello World") call abort
+end program
+

diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index e0039ec..7f1bff2 100644 (file)
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,7 @@
+2004-08-27  Paul Brook  <paul@codesourcery.com>
+
+       * io/rewind.c (st_rewind): Reset unit to read mode.
+
 2004-08-27  Bud Davis  <bdavis9659@comcast.net>
 
        PR fortran/16597

diff --git a/libgfortran/io/rewind.c b/libgfortran/io/rewind.c
index d9758a6..7be2328 100644 (file)
--- a/libgfortran/io/rewind.c
+++ b/libgfortran/io/rewind.c
@@ -40,8 +40,13 @@ st_rewind (void)
                        "Cannot REWIND a file opened for DIRECT access");
       else
        {
+         /* If we have been writing to the file, the last written record
+            is the last record in the file, so trincate the file now.
+            Reset to read mode so two consecutive rewind statements
+            don't delete the file contents.  */
           if (u->mode==WRITING)
             struncate(u->s);
+         u->mode = READING;
          u->last_record = 0;
          if (sseek (u->s, 0) == FAILURE)
            generate_error (ERROR_OS, NULL);