Index: a-direct.adb
===================================================================
--- a-direct.adb	(revision 247293)
+++ a-direct.adb	(working copy)
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 2004-2016, Free Software Foundation, Inc.         --
+--          Copyright (C) 2004-2017, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -528,6 +528,10 @@
    begin
       Local_Get_Current_Dir (Buffer'Address, Path_Len'Address);
 
+      if Path_Len = 0 then
+         raise Use_Error with "current directory does not exist";
+      end if;
+
       --  We need to resolve links because of RM A.16(47), which requires
       --  that we not return alternative names for files.
 
Index: g-dirope.adb
===================================================================
--- g-dirope.adb	(revision 247293)
+++ g-dirope.adb	(working copy)
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---                     Copyright (C) 1998-2014, AdaCore                     --
+--                     Copyright (C) 1998-2017, AdaCore                     --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -29,6 +29,7 @@
 --                                                                          --
 ------------------------------------------------------------------------------
 
+with Ada.IO_Exceptions;
 with Ada.Characters.Handling;
 with Ada.Strings.Fixed;
 
@@ -573,6 +574,11 @@
    begin
       Local_Get_Current_Dir (Buffer'Address, Path_Len'Address);
 
+      if Path_Len = 0 then
+         raise Ada.IO_Exceptions.Use_Error
+           with "current directory does not exist";
+      end if;
+
       Last :=
         (if Dir'Length > Path_Len then Dir'First + Path_Len - 1 else Dir'Last);
 
Index: adaint.c
===================================================================
--- adaint.c	(revision 247293)
+++ adaint.c	(working copy)
@@ -6,7 +6,7 @@
  *                                                                          *
  *                          C Implementation File                           *
  *                                                                          *
- *          Copyright (C) 1992-2015, Free Software Foundation, Inc.         *
+ *          Copyright (C) 1992-2017, Free Software Foundation, Inc.         *
  *                                                                          *
  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  * terms of the  GNU General Public License as published  by the Free Soft- *
@@ -613,7 +613,16 @@
   WS2SC (dir, wdir, GNAT_MAX_PATH_LEN);
 
 #else
-   getcwd (dir, *length);
+   char* result = getcwd (dir, *length);
+   /* If the current directory does not exist, set length = 0
+      to indicate error. That can't happen on windows, where
+      you can't delete a directory if it is the current
+      directory of some process. */
+   if (!result)
+     {
+       *length = 0;
+       return;
+     }
 #endif
 
    *length = strlen (dir);
Index: osint.adb
===================================================================
--- osint.adb	(revision 247293)
+++ osint.adb	(working copy)
@@ -1550,6 +1550,10 @@
          begin
             Get_Current_Dir (Buffer'Address, Path_Len'Address);
 
+            if Path_Len = 0 then
+               raise Program_Error;
+            end if;
+
             if Buffer (Path_Len) /= Directory_Separator then
                Path_Len := Path_Len + 1;
                Buffer (Path_Len) := Directory_Separator;
Index: s-os_lib.adb
===================================================================
--- s-os_lib.adb	(revision 247293)
+++ s-os_lib.adb	(working copy)
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---                     Copyright (C) 1995-2016, AdaCore                     --
+--                     Copyright (C) 1995-2017, AdaCore                     --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -2191,6 +2191,10 @@
             begin
                Get_Current_Dir (Buffer'Address, Path_Len'Address);
 
+               if Path_Len = 0 then
+                  raise Program_Error;
+               end if;
+
                if Buffer (Path_Len) /= Directory_Separator then
                   Path_Len := Path_Len + 1;
                   Buffer (Path_Len) := Directory_Separator;