2017-12-16 Jerry DeLisle <jvdelisle@gcc.gnu.org>

	Backport from trunk
	PR libgfortran/78549
	* io/inquire.c (inquire_via_unit): Adjust test for existence for
	pre-connected internal units.
	* io/transfer.c (finalize_transfer): When done with a transfer
	to internal units, free the format buffer and close the stream.
	(st_read_done): Delete freeing the stream, now handled using
	sclose in finalize_transfer. (st_write_done): Likewise.
	* io/unit.c (get_unit): Return NULL for special reserved unit
	numbers, signifying not accessible to the user.
	(init_units): Insert the two special internal units into the
	unit treap. This makes these unit structures available without
	further allocations for later use by internal unit I/O. These
	units are automatically deleted by normal program termination.
	* io/unix.c (mem_close): Add a guard check to protect from double free.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-7-branch@255751 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 45 insertions, 8 deletions

diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index 986b2b0a31e3..83147ac776bc 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,21 @@
+2017-12-16  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
+
+	Backport from trunk
+	PR libgfortran/78549
+	* io/inquire.c (inquire_via_unit): Adjust test for existence for
+	pre-connected internal units.
+	* io/transfer.c (finalize_transfer): When done with a transfer
+	to internal units, free the format buffer and close the stream.
+	(st_read_done): Delete freeing the stream, now handled using
+	sclose in finalize_transfer. (st_write_done): Likewise.
+	* io/unit.c (get_unit): Return NULL for special reserved unit
+	numbers, signifying not accessible to the user.
+	(init_units): Insert the two special internal units into the
+	unit treap. This makes these unit structures available without
+	further allocations for later use by internal unit I/O. These
+	units are automatically deleted by normal program termination.
+	* io/unix.c (mem_close): Add a guard check to protect from double free.
+
 2017-12-03  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	Backport from trunk
diff --git a/libgfortran/io/inquire.c b/libgfortran/io/inquire.c
index 4cf87d339a7f..da5b674a8916 100644
--- a/libgfortran/io/inquire.c
+++ b/libgfortran/io/inquire.c
@@ -47,7 +47,10 @@ inquire_via_unit (st_parameter_inquire *iqp, gfc_unit *u)
     generate_error (&iqp->common, LIBERROR_INQUIRE_INTERNAL_UNIT, NULL);
 
   if ((cf & IOPARM_INQUIRE_HAS_EXIST) != 0)
-    *iqp->exist = (u != NULL) || (iqp->common.unit >= 0);
+    *iqp->exist = (u != NULL &&
+		   iqp->common.unit != GFC_INTERNAL_UNIT &&
+		   iqp->common.unit != GFC_INTERNAL_UNIT4)
+		|| (iqp->common.unit >= 0);
 
   if ((cf & IOPARM_INQUIRE_HAS_OPENED) != 0)
     *iqp->opened = (u != NULL);
diff --git a/libgfortran/io/transfer.c b/libgfortran/io/transfer.c
index 316d3283669a..7d270fb8b369 100644
--- a/libgfortran/io/transfer.c
+++ b/libgfortran/io/transfer.c
@@ -3984,6 +3984,19 @@ finalize_transfer (st_parameter_dt *dtp)
   next_record (dtp, 1);
 
  done:
+
+  if (dtp->u.p.unit_is_internal)
+    {
+      fbuf_destroy (dtp->u.p.current_unit);
+      if (dtp->u.p.current_unit
+	  && (dtp->u.p.current_unit->child_dtio  == 0)
+	  && dtp->u.p.current_unit->s)
+	{
+	  sclose (dtp->u.p.current_unit->s);
+	  dtp->u.p.current_unit->s = NULL;
+	}
+    }
+
 #ifdef HAVE_USELOCALE
   if (dtp->u.p.old_locale != (locale_t) 0)
     {
@@ -4093,8 +4106,6 @@ st_read_done (st_parameter_dt *dtp)
 	    {
 	      free (dtp->u.p.current_unit->filename);
 	      dtp->u.p.current_unit->filename = NULL;
-	      free (dtp->u.p.current_unit->s);
-	      dtp->u.p.current_unit->s = NULL;
 	      if (dtp->u.p.current_unit->ls)
 		free (dtp->u.p.current_unit->ls);
 	      dtp->u.p.current_unit->ls = NULL;
@@ -4164,8 +4175,6 @@ st_write_done (st_parameter_dt *dtp)
 	    {
 	      free (dtp->u.p.current_unit->filename);
 	      dtp->u.p.current_unit->filename = NULL;
-	      free (dtp->u.p.current_unit->s);
-	      dtp->u.p.current_unit->s = NULL;
 	      if (dtp->u.p.current_unit->ls)
 		free (dtp->u.p.current_unit->ls);
 	      dtp->u.p.current_unit->ls = NULL;
diff --git a/libgfortran/io/unit.c b/libgfortran/io/unit.c
index 4b49b26311c5..769c7cc1da24 100644
--- a/libgfortran/io/unit.c
+++ b/libgfortran/io/unit.c
@@ -563,7 +563,11 @@ get_unit (st_parameter_dt *dtp, int do_create)
      is not allowed, such units must be created with
      OPEN(NEWUNIT=...).  */
   if (dtp->common.unit < 0)
-    return get_gfc_unit (dtp->common.unit, 0);
+    {
+      if (dtp->common.unit > NEWUNIT_START) /* Reserved units.  */
+	return NULL;
+      return get_gfc_unit (dtp->common.unit, 0);
+    }
 
   return get_gfc_unit (dtp->common.unit, do_create);
 }
@@ -683,6 +687,9 @@ init_units (void)
 
       __gthread_mutex_unlock (&u->lock);
     }
+  /* The default internal units.  */
+  u = insert_unit (GFC_INTERNAL_UNIT);
+  u = insert_unit (GFC_INTERNAL_UNIT4);
 
   /* Calculate the maximum file offset in a portable manner.
      max will be the largest signed number for the type gfc_offset.
diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index c76b427387ad..20320776e5fd 100644
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -959,8 +959,8 @@ mem_flush (unix_stream *s __attribute__ ((unused)))
 static int
 mem_close (unix_stream *s)
 {
-  free (s);
-
+  if (s)
+    free (s);
   return 0;
 }