Keep w32 environment settings internal only

* src/emacs.c (main) [WINDOWSNT]: Move init_environment calls after the
set_initial_environment call.  This prevents Emacs' modifications to the
environment from contaminating Vprocess_environment and
Vinitial_environment (Bug #10980).
* src/callproc.c (getenv_internal) [WINDOWSNT]: Consult Emacs' internal
environment in as a fallback to Vprocess_environment.
* test/src/callproc-tests.el (initial-environment-preserved): New Test.

3 files changed, 67 insertions, 10 deletions

diff --git a/src/callproc.c b/src/callproc.c
index 7008b916da..e8d089cf20 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -1375,6 +1375,20 @@ getenv_internal (const char *var, ptrdiff_t varlen, char **value,
 			 Vprocess_environment))
     return *value ? 1 : 0;
 
+  /* On Windows we make some modifications to Emacs' enviroment
+     without recording them in Vprocess_environment.  */
+#ifdef WINDOWSNT
+  {
+    char* tmpval = getenv (var);
+    if (tmpval)
+      {
+        *value = tmpval;
+        *valuelen = strlen (tmpval);
+        return 1;
+      }
+  }
+#endif
+
   /* For DISPLAY try to get the values from the frame or the initial env.  */
   if (strcmp (var, "DISPLAY") == 0)
     {
diff --git a/src/emacs.c b/src/emacs.c
index b2219844ca..fa7ec017fb 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1349,16 +1349,6 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
   globals_of_gfilenotify ();
 #endif
 
-#ifdef WINDOWSNT
-  globals_of_w32 ();
-#ifdef HAVE_W32NOTIFY
-  globals_of_w32notify ();
-#endif
-  /* Initialize environment from registry settings.  */
-  init_environment (argv);
-  init_ntproc (dumping); /* must precede init_editfns.  */
-#endif
-
 #ifdef HAVE_NS
   /* Initialize the locale from user defaults.  */
   ns_init_locale ();
@@ -1375,6 +1365,20 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
   if (! dumping)
     set_initial_environment ();
 
+#ifdef WINDOWSNT
+  globals_of_w32 ();
+#ifdef HAVE_W32NOTIFY
+  globals_of_w32notify ();
+#endif
+  /* Initialize environment from registry settings.  Make sure to do
+     this only after calling set_initial_environment so that
+     Vinitial_environment and Vprocess_environment will contain only
+     variables from the parent process without modifications from
+     Emacs.  */
+  init_environment (argv);
+  init_ntproc (dumping); /* must precede init_editfns.  */
+#endif
+
   /* AIX crashes are reported in system versions 3.2.3 and 3.2.4
      if this is not done.  Do it after set_global_environment so that we
      don't pollute Vglobal_environment.  */
diff --git a/test/src/callproc-tests.el b/test/src/callproc-tests.el
new file mode 100644
index 0000000000..46541aba78
--- /dev/null
+++ b/test/src/callproc-tests.el
@@ -0,0 +1,39 @@
+;;; callproc-tests.el --- callproc.c tests -*- lexical-binding: t -*-
+
+;; Copyright (C) 2016 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(eval-when-compile (require 'cl-lib))
+
+(ert-deftest initial-environment-preserved ()
+  "Check that `initial-environment' is not modified by Emacs (Bug #10980)."
+  (skip-unless (eq system-type 'windows-nt))
+  (cl-destructuring-bind (initial-shell shell)
+      (with-temp-buffer
+        (let ((process-environment (cons "SHELL" process-environment)))
+          (call-process (expand-file-name invocation-name invocation-directory)
+                        nil t nil
+                        "--batch" "-Q" "--eval"
+                        (prin1-to-string
+                         '(progn (prin1 (getenv-internal "SHELL" initial-environment))
+                                 (prin1 (getenv-internal "SHELL"))))))
+        (split-string-and-unquote (buffer-string)))
+    (should (equal initial-shell "nil"))
+    (should-not (equal initial-shell shell))))